Multi-Attribute Task Battery - Applications in pilot workload and strategic behavior research

NASA Technical Reports Server (NTRS)

Arnegard, Ruth J.; Comstock, J. R., Jr.

1991-01-01

The Multi-Attribute Task (MAT) Battery provides a benchmark set of tasks for use in a wide range of lab studies of operator performance and workload. The battery incorporates tasks analogous to activities that aircraft crewmembers perform in flight, while providing a high degree of experimenter control, performance data on each subtask, and freedom to nonpilot test subjects. Features not found in existing computer based tasks include an auditory communication task (to simulate Air Traffic Control communication), a resource management task permitting many avenues or strategies of maintaining target performance, a scheduling window which gives the operator information about future task demands, and the option of manual or automated control of tasks. Performance data are generated for each subtask. In addition, the task battery may be paused and onscreen workload rating scales presented to the subject. The MAT Battery requires a desktop computer with color graphics. The communication task requires a serial link to a second desktop computer with a voice synthesizer or digitizer card.

The multi-attribute task battery for human operator workload and strategic behavior research

NASA Technical Reports Server (NTRS)

Comstock, J. Raymond, Jr.; Arnegard, Ruth J.

1992-01-01

The Multi-Attribute Task (MAT) Battery provides a benchmark set of tasks for use in a wide range of lab studies of operator performance and workload. The battery incorporates tasks analogous to activities that aircraft crewmembers perform in flight, while providing a high degree of experimenter control, performance data on each subtask, and freedom to use nonpilot test subjects. Features not found in existing computer based tasks include an auditory communication task (to simulate Air Traffic Control communication), a resource management task permitting many avenues or strategies of maintaining target performance, a scheduling window which gives the operator information about future task demands, and the option of manual or automated control of tasks. Performance data are generated for each subtask. In addition, the task battery may be paused and onscreen workload rating scales presented to the subject. The MAT Battery requires a desktop computer with color graphics. The communication task requires a serial link to a second desktop computer with a voice synthesizer or digitizer card.

Task Assignment Heuristics for Distributed CFD Applications

NASA Technical Reports Server (NTRS)

Lopez-Benitez, N.; Djomehri, M. J.; Biswas, R.; Biegel, Bryan (Technical Monitor)

2001-01-01

CFD applications require high-performance computational platforms: 1. Complex physics and domain configuration demand strongly coupled solutions; 2. Applications are CPU and memory intensive; and 3. Huge resource requirements can only be satisfied by teraflop-scale machines or distributed computing.

The role of early visual cortex in visual short-term memory and visual attention.

PubMed

Offen, Shani; Schluppeck, Denis; Heeger, David J

2009-06-01

We measured cortical activity with functional magnetic resonance imaging to probe the involvement of early visual cortex in visual short-term memory and visual attention. In four experimental tasks, human subjects viewed two visual stimuli separated by a variable delay period. The tasks placed differential demands on short-term memory and attention, but the stimuli were visually identical until after the delay period. Early visual cortex exhibited sustained responses throughout the delay when subjects performed attention-demanding tasks, but delay-period activity was not distinguishable from zero when subjects performed a task that required short-term memory. This dissociation reveals different computational mechanisms underlying the two processes.

Π4U: A high performance computing framework for Bayesian uncertainty quantification of complex models

NASA Astrophysics Data System (ADS)

Hadjidoukas, P. E.; Angelikopoulos, P.; Papadimitriou, C.; Koumoutsakos, P.

2015-03-01

We present Π4U, an extensible framework, for non-intrusive Bayesian Uncertainty Quantification and Propagation (UQ+P) of complex and computationally demanding physical models, that can exploit massively parallel computer architectures. The framework incorporates Laplace asymptotic approximations as well as stochastic algorithms, along with distributed numerical differentiation and task-based parallelism for heterogeneous clusters. Sampling is based on the Transitional Markov Chain Monte Carlo (TMCMC) algorithm and its variants. The optimization tasks associated with the asymptotic approximations are treated via the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). A modified subset simulation method is used for posterior reliability measurements of rare events. The framework accommodates scheduling of multiple physical model evaluations based on an adaptive load balancing library and shows excellent scalability. In addition to the software framework, we also provide guidelines as to the applicability and efficiency of Bayesian tools when applied to computationally demanding physical models. Theoretical and computational developments are demonstrated with applications drawn from molecular dynamics, structural dynamics and granular flow.

Programming distributed medical applications with XWCH2.

PubMed

Ben Belgacem, Mohamed; Niinimaki, Marko; Abdennadher, Nabil

2010-01-01

Many medical applications utilise distributed/parallel computing in order to cope with demands of large data or computing power requirements. In this paper, we present a new version of the XtremWeb-CH (XWCH) platform, and demonstrate two medical applications that run on XWCH. The platform is versatile in a way that it supports direct communication between tasks. When tasks cannot communicate directly, warehouses are used as intermediary nodes between "producer" and "consumer" tasks. New features have been developed to provide improved support for writing powerfull distributed applications using an easy API.

Vision-related problems among the workers engaged in jewellery manufacturing.

PubMed

Salve, Urmi Ravindra

2015-01-01

American Optometric Association defines Computer Vision Syndrome (CVS) as "complex of eye and vision problems related to near work which are experienced during or related to computer use." This happens when visual demand of the tasks exceeds the visual ability of the users. Even though problems were initially attributed to computer-related activities subsequently similar problems are also reported while carrying any near point task. Jewellery manufacturing activities involves precision designs, setting the tiny metals and stones which requires high visual attention and mental concentration and are often near point task. It is therefore expected that the workers engaged in jewellery manufacturing may also experience symptoms like CVS. Keeping the above in mind, this study was taken up (1) To identify the prevalence of symptoms like CVS among the workers of the jewellery manufacturing and compare the same with the workers working at computer workstation and (2) To ascertain whether such symptoms have any permanent vision-related problems. Case control study. The study was carried out in Zaveri Bazaar region and at an IT-enabled organization in Mumbai. The study involved the identification of symptoms of CVS using a questionnaire of Eye Strain Journal, opthalmological check-ups and measurement of Spontaneous Eye Blink rate. The data obtained from the jewellery manufacturing was compared with the data of the subjects engaged in computer work and with the data available in the literature. A comparative inferential statistics was used. Results showed that visual demands of the task carried out in jewellery manufacturing were much higher than that of carried out in computer-related work.

The effects of advertisement location and familiarity on selective attention.

PubMed

Jessen, Tanja Lund; Rodway, Paul

2010-06-01

This study comprised two experiments to examine the distracting effects of advertisement familiarity, location, and onset on the performance of a selective attention task. In Exp. 1, familiar advertisements presented in peripheral vision disrupted selective attention when the attention task was more demanding, suggesting that the distracting effect of advertisements is a product of task demands and advertisement familiarity and location. In Exp. 2, the onset of the advertisement shortly before, or after, the attention task captured attention and disrupted attentional performance. The onset of the advertisement before the attention task reduced target response time without an increase in errors and therefore facilitated performance. Despite being instructed to ignore the advertisements, the participants were able to recall a substantial proportion of the familiar advertisements. Implications for the presentation of advertisements during human-computer interaction were discussed.

An Undergraduate Computer Engineering Option for Electrical Engineering.

ERIC Educational Resources Information Center

National Academy of Engineering, Washington, DC. Commission on Education.

This report is the result of a study, funded by the National Science Foundation, of a group constituted as the COSINE Task Force on Undergraduate Education in Computer Engineering in 1969. The group was formed in response to the growing demand for education in computer engineering and the limited opportunities for study in this area. Computer…

College and the Digital Generation: Assessing and Training Students for the Technological Demands of College by Exploring Relationships between Computer Self-Efficacy and Computer Proficiency

ERIC Educational Resources Information Center

Morris, Kathleen M.

2010-01-01

Today's college students are often labeled the "Net Generation" and assumed to be computer savvy and technological minded. Exposure to and use of technologies can increase self-efficacy regarding ability to complete desired computer tasks, but students arrive on campuses unable to pass computer proficiency exams. This is concerning because some…

Interhemispheric interaction expands attentional capacity in an auditory selective attention task.

PubMed

Scalf, Paige E; Banich, Marie T; Erickson, Andrew B

2009-04-01

Previous work from our laboratory indicates that interhemispheric interaction (IHI) functionally increases the attentional capacity available to support performance on visual tasks (Banich in The asymmetrical brain, pp 261-302, 2003). Because manipulations of both computational complexity and selection demand alter the benefits of IHI to task performance, we argue that IHI may be a general strategy for meeting increases in attentional demand. Other researchers, however, have suggested that the apparent benefits of IHI to attentional capacity are an epiphenomenon of the organization of the visual system (Fecteau and Enns in Neuropsychologia 43:1412-1428, 2005; Marsolek et al. in Neuropsychologia 40:1983-1999, 2002). In the current experiment, we investigate whether IHI increases attentional capacity outside the visual system by manipulating the selection demands of an auditory temporal pattern-matching task. We find that IHI expands attentional capacity in the auditory system. This suggests that the benefits of requiring IHI derive from a functional increase in attentional capacity rather than the organization of a specific sensory modality.

MAT - MULTI-ATTRIBUTE TASK BATTERY FOR HUMAN OPERATOR WORKLOAD AND STRATEGIC BEHAVIOR RESEARCH

NASA Technical Reports Server (NTRS)

Comstock, J. R.

1994-01-01

MAT, a Multi-Attribute Task battery, gives the researcher the capability of performing multi-task workload and performance experiments. The battery provides a benchmark set of tasks for use in a wide range of laboratory studies of operator performance and workload. MAT incorporates tasks analogous to activities that aircraft crew members perform in flight, while providing a high degree of experiment control, performance data on each subtask, and freedom to use non-pilot test subjects. The MAT battery primary display is composed of four separate task windows which are as follows: a monitoring task window which includes gauges and warning lights, a tracking task window for the demands of manual control, a communication task window to simulate air traffic control communications, and a resource management task window which permits maintaining target levels on a fuel management task. In addition, a scheduling task window gives the researcher information about future task demands. The battery also provides the option of manual or automated control of tasks. The task generates performance data for each subtask. The task battery may be paused and onscreen workload rating scales presented to the subject. The MAT battery was designed to use a serially linked second computer to generate the voice messages for the Communications task. The MATREMX program and support files, which are included in the MAT package, were designed to work with the Heath Voice Card (Model HV-2000, available through the Heath Company, Benton Harbor, Michigan 49022); however, the MATREMX program and support files may easily be modified to work with other voice synthesizer or digitizer cards. The MAT battery task computer may also be used independent of the voice computer if no computer synthesized voice messages are desired or if some other method of presenting auditory messages is devised. MAT is written in QuickBasic and assembly language for IBM PC series and compatible computers running MS-DOS. The code in MAT is written for Microsoft QuickBasic 4.5 and Microsoft Macro Assembler 5.1. This package requires a joystick and EGA or VGA color graphics. An 80286, 386, or 486 processor machine is highly recommended. The standard distribution medium for MAT is a 5.25 inch 360K MS-DOS format diskette. The files are compressed using the PKZIP file compression utility. PKUNZIP is included on the distribution diskette. MAT was developed in 1992. IBM PC is a registered trademark of International Business Machines. MS-DOS, Microsoft QuickBasic, and Microsoft Macro Assembler are registered trademarks of Microsoft Corporation. PKZIP and PKUNZIP are registered trademarks of PKWare, Inc.

Demand Response Resource Quantification with Detailed Building Energy Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hale, Elaine; Horsey, Henry; Merket, Noel

Demand response is a broad suite of technologies that enables changes in electrical load operations in support of power system reliability and efficiency. Although demand response is not a new concept, there is new appetite for comprehensively evaluating its technical potential in the context of renewable energy integration. The complexity of demand response makes this task difficult -- we present new methods for capturing the heterogeneity of potential responses from buildings, their time-varying nature, and metrics such as thermal comfort that help quantify likely acceptability of specific demand response actions. Computed with an automated software framework, the methods are scalable.

VM Capacity-Aware Scheduling within Budget Constraints in IaaS Clouds

PubMed Central

Thanasias, Vasileios; Lee, Choonhwa; Hanif, Muhammad; Kim, Eunsam; Helal, Sumi

2016-01-01

Recently, cloud computing has drawn significant attention from both industry and academia, bringing unprecedented changes to computing and information technology. The infrastructure-as-a-Service (IaaS) model offers new abilities such as the elastic provisioning and relinquishing of computing resources in response to workload fluctuations. However, because the demand for resources dynamically changes over time, the provisioning of resources in a way that a given budget is efficiently utilized while maintaining a sufficing performance remains a key challenge. This paper addresses the problem of task scheduling and resource provisioning for a set of tasks running on IaaS clouds; it presents novel provisioning and scheduling algorithms capable of executing tasks within a given budget, while minimizing the slowdown due to the budget constraint. Our simulation study demonstrates a substantial reduction up to 70% in the overall task slowdown rate by the proposed algorithms. PMID:27501046

VM Capacity-Aware Scheduling within Budget Constraints in IaaS Clouds.

PubMed

Thanasias, Vasileios; Lee, Choonhwa; Hanif, Muhammad; Kim, Eunsam; Helal, Sumi

2016-01-01

Recently, cloud computing has drawn significant attention from both industry and academia, bringing unprecedented changes to computing and information technology. The infrastructure-as-a-Service (IaaS) model offers new abilities such as the elastic provisioning and relinquishing of computing resources in response to workload fluctuations. However, because the demand for resources dynamically changes over time, the provisioning of resources in a way that a given budget is efficiently utilized while maintaining a sufficing performance remains a key challenge. This paper addresses the problem of task scheduling and resource provisioning for a set of tasks running on IaaS clouds; it presents novel provisioning and scheduling algorithms capable of executing tasks within a given budget, while minimizing the slowdown due to the budget constraint. Our simulation study demonstrates a substantial reduction up to 70% in the overall task slowdown rate by the proposed algorithms.

Cognitive Computer Tools in the Teaching and Learning of Undergraduate Calculus

ERIC Educational Resources Information Center

Borchelt, Nathan

2007-01-01

The purpose of this study was to explore the use of a cognitive computer tool by undergraduate calculus students as they worked cooperatively on mathematical tasks. Specific attention was given to levels of cognitive demand in which the students were engaged as they completed in-class labs with the assistance of MathCAD. Participants were assigned…

Word Learning Deficits in Children With Dyslexia

PubMed Central

Hogan, Tiffany; Green, Samuel; Gray, Shelley; Cabbage, Kathryn; Cowan, Nelson

2017-01-01

Purpose The purpose of this study is to investigate word learning in children with dyslexia to ascertain their strengths and weaknesses during the configuration stage of word learning. Method Children with typical development (N = 116) and dyslexia (N = 68) participated in computer-based word learning games that assessed word learning in 4 sets of games that manipulated phonological or visuospatial demands. All children were monolingual English-speaking 2nd graders without oral language impairment. The word learning games measured children's ability to link novel names with novel objects, to make decisions about the accuracy of those names and objects, to recognize the semantic features of the objects, and to produce the names of the novel words. Accuracy data were analyzed using analyses of covariance with nonverbal intelligence scores as a covariate. Results Word learning deficits were evident for children with dyslexia across every type of manipulation and on 3 of 5 tasks, but not for every combination of task/manipulation. Deficits were more common when task demands taxed phonology. Visuospatial manipulations led to both disadvantages and advantages for children with dyslexia. Conclusion Children with dyslexia evidence spoken word learning deficits, but their performance is highly dependent on manipulations and task demand, suggesting a processing trade-off between visuospatial and phonological demands. PMID:28388708

Cognitive simulation as a tool for cognitive task analysis.

PubMed

Roth, E M; Woods, D D; Pople, H E

1992-10-01

Cognitive simulations are runnable computer programs that represent models of human cognitive activities. We show how one cognitive simulation built as a model of some of the cognitive processes involved in dynamic fault management can be used in conjunction with small-scale empirical data on human performance to uncover the cognitive demands of a task, to identify where intention errors are likely to occur, and to point to improvements in the person-machine system. The simulation, called Cognitive Environment Simulation or CES, has been exercised on several nuclear power plant accident scenarios. Here we report one case to illustrate how a cognitive simulation tool such as CES can be used to clarify the cognitive demands of a problem-solving situation as part of a cognitive task analysis.

Man-machine Integration Design and Analysis System (MIDAS) Task Loading Model (TLM) experimental and software detailed design report

NASA Technical Reports Server (NTRS)

Staveland, Lowell

1994-01-01

This is the experimental and software detailed design report for the prototype task loading model (TLM) developed as part of the man-machine integration design and analysis system (MIDAS), as implemented and tested in phase 6 of the Army-NASA Aircrew/Aircraft Integration (A3I) Program. The A3I program is an exploratory development effort to advance the capabilities and use of computational representations of human performance and behavior in the design, synthesis, and analysis of manned systems. The MIDAS TLM computationally models the demands designs impose on operators to aide engineers in the conceptual design of aircraft crewstations. This report describes TLM and the results of a series of experiments which were run this phase to test its capabilities as a predictive task demand modeling tool. Specifically, it includes discussions of: the inputs and outputs of TLM, the theories underlying it, the results of the test experiments, the use of the TLM as both stand alone tool and part of a complete human operator simulation, and a brief introduction to the TLM software design.

Ubiquitous Green Computing Techniques for High Demand Applications in Smart Environments

PubMed Central

Zapater, Marina; Sanchez, Cesar; Ayala, Jose L.; Moya, Jose M.; Risco-Martín, José L.

2012-01-01

Ubiquitous sensor network deployments, such as the ones found in Smart cities and Ambient intelligence applications, require constantly increasing high computational demands in order to process data and offer services to users. The nature of these applications imply the usage of data centers. Research has paid much attention to the energy consumption of the sensor nodes in WSNs infrastructures. However, supercomputing facilities are the ones presenting a higher economic and environmental impact due to their very high power consumption. The latter problem, however, has been disregarded in the field of smart environment services. This paper proposes an energy-minimization workload assignment technique, based on heterogeneity and application-awareness, that redistributes low-demand computational tasks from high-performance facilities to idle nodes with low and medium resources in the WSN infrastructure. These non-optimal allocation policies reduce the energy consumed by the whole infrastructure and the total execution time. PMID:23112621

Ubiquitous green computing techniques for high demand applications in Smart environments.

PubMed

Zapater, Marina; Sanchez, Cesar; Ayala, Jose L; Moya, Jose M; Risco-Martín, José L

2012-01-01

Ubiquitous sensor network deployments, such as the ones found in Smart cities and Ambient intelligence applications, require constantly increasing high computational demands in order to process data and offer services to users. The nature of these applications imply the usage of data centers. Research has paid much attention to the energy consumption of the sensor nodes in WSNs infrastructures. However, supercomputing facilities are the ones presenting a higher economic and environmental impact due to their very high power consumption. The latter problem, however, has been disregarded in the field of smart environment services. This paper proposes an energy-minimization workload assignment technique, based on heterogeneity and application-awareness, that redistributes low-demand computational tasks from high-performance facilities to idle nodes with low and medium resources in the WSN infrastructure. These non-optimal allocation policies reduce the energy consumed by the whole infrastructure and the total execution time.

Production practices affecting worker task demands in concrete operations: A case study.

PubMed

Memarian, Babak; Mitropoulos, Panagiotis

2015-01-01

Construction work involves significant physical, mental, and temporal task demands. Excessive task demands can have negative consequences for safety, errors and production. This exploratory study investigates the magnitude and sources of task demands on a concrete operation, and examines the effect of the production practices on the workers' task demands. The NASA Task Load Index was used to measure the perceived task demands of two work crews. The operation involved the construction of a cast-in-place concrete building under high schedule pressures. Interviews with each crew member were used to identify the main sources of the perceived demands. Extensive field observations and interviews with the supervisors and crews identified the production practices. The workers perceived different level of task demands depending on their role. The production practices influenced the task demands in two ways: (1) practices related to work organization, task design, resource management, and crew management mitigated the task demands; and (2) other practices related to work planning and crew management increased the crew's ability to cope with and adapt to high task demands. The findings identify production practices that regulate the workers' task demands. The effect of task demands on performance is mitigated by the ability to cope with high demands.

Application of evolutionary computation in ECAD problems

NASA Astrophysics Data System (ADS)

Lee, Dae-Hyun; Hwang, Seung H.

1998-10-01

Design of modern electronic system is a complicated task which demands the use of computer- aided design (CAD) tools. Since a lot of problems in ECAD are combinatorial optimization problems, evolutionary computations such as genetic algorithms and evolutionary programming have been widely employed to solve those problems. We have applied evolutionary computation techniques to solve ECAD problems such as technology mapping, microcode-bit optimization, data path ordering and peak power estimation, where their benefits are well observed. This paper presents experiences and discusses issues in those applications.

Validated Predictions of Metabolic Energy Consumption for Submaximal Effort Movement

PubMed Central

Tsianos, George A.; MacFadden, Lisa N.

2016-01-01

Physical performance emerges from complex interactions among many physiological systems that are largely driven by the metabolic energy demanded. Quantifying metabolic demand is an essential step for revealing the many mechanisms of physical performance decrement, but accurate predictive models do not exist. The goal of this study was to investigate if a recently developed model of muscle energetics and force could be extended to reproduce the kinematics, kinetics, and metabolic demand of submaximal effort movement. Upright dynamic knee extension against various levels of ergometer load was simulated. Task energetics were estimated by combining the model of muscle contraction with validated models of lower limb musculotendon paths and segment dynamics. A genetic algorithm was used to compute the muscle excitations that reproduced the movement with the lowest energetic cost, which was determined to be an appropriate criterion for this task. Model predictions of oxygen uptake rate (VO2) were well within experimental variability for the range over which the model parameters were confidently known. The model's accurate estimates of metabolic demand make it useful for assessing the likelihood and severity of physical performance decrement for a given task as well as investigating underlying physiologic mechanisms. PMID:27248429

A highly efficient multi-core algorithm for clustering extremely large datasets

PubMed Central

2010-01-01

Background In recent years, the demand for computational power in computational biology has increased due to rapidly growing data sets from microarray and other high-throughput technologies. This demand is likely to increase. Standard algorithms for analyzing data, such as cluster algorithms, need to be parallelized for fast processing. Unfortunately, most approaches for parallelizing algorithms largely rely on network communication protocols connecting and requiring multiple computers. One answer to this problem is to utilize the intrinsic capabilities in current multi-core hardware to distribute the tasks among the different cores of one computer. Results We introduce a multi-core parallelization of the k-means and k-modes cluster algorithms based on the design principles of transactional memory for clustering gene expression microarray type data and categorial SNP data. Our new shared memory parallel algorithms show to be highly efficient. We demonstrate their computational power and show their utility in cluster stability and sensitivity analysis employing repeated runs with slightly changed parameters. Computation speed of our Java based algorithm was increased by a factor of 10 for large data sets while preserving computational accuracy compared to single-core implementations and a recently published network based parallelization. Conclusions Most desktop computers and even notebooks provide at least dual-core processors. Our multi-core algorithms show that using modern algorithmic concepts, parallelization makes it possible to perform even such laborious tasks as cluster sensitivity and cluster number estimation on the laboratory computer. PMID:20370922

Lessons learned from the usability assessment of home-based telemedicine systems.

PubMed

Agnisarman, Sruthy Orozhiyathumana; Chalil Madathil, Kapil; Smith, Kevin; Ashok, Aparna; Welch, Brandon; McElligott, James T

2017-01-01

At-home telemedicine visits are quickly becoming an acceptable alternative for in-person patient visits. However, little work has been done to understand the usability of these home-based telemedicine solutions. It is critical for user acceptance and real-world applicability to evaluate available telemedicine solutions within the context-specific needs of the users of this technology. To address this need, this study evaluated the usability of four home-based telemedicine software platforms: Doxy.me, Vidyo, VSee, and Polycom. Using a within-subjects experimental design, twenty participants were asked to complete a telemedicine session involving several tasks using the four platforms. Upon completion of these tasks for each platform, participants completed the IBM computer system usability questionnaire (CSUQ) and the NASA Task Load Index test. Upon completing the tasks on all four platforms, the participants completed a final post-test subjective questionnaire ranking the platforms based on their preference. Of the twenty participants, 19 completed the study. Statistically significant differences among the telemedicine software platforms were found for task completion time, total workload, mental demand, effort, frustration, preference ranking and computer system usability scores. Usability problems with installation and account creation led to high mental demand and task completion time, suggesting the participants preferred a system without such requirements. Majority of the usability issues were identified at the telemedicine initiation phase. The findings from this study can be used by software developers to develop user-friendly telemedicine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design and Analysis of Self-Adapted Task Scheduling Strategies in Wireless Sensor Networks

PubMed Central

Guo, Wenzhong; Xiong, Naixue; Chao, Han-Chieh; Hussain, Sajid; Chen, Guolong

2011-01-01

In a wireless sensor network (WSN), the usage of resources is usually highly related to the execution of tasks which consume a certain amount of computing and communication bandwidth. Parallel processing among sensors is a promising solution to provide the demanded computation capacity in WSNs. Task allocation and scheduling is a typical problem in the area of high performance computing. Although task allocation and scheduling in wired processor networks has been well studied in the past, their counterparts for WSNs remain largely unexplored. Existing traditional high performance computing solutions cannot be directly implemented in WSNs due to the limitations of WSNs such as limited resource availability and the shared communication medium. In this paper, a self-adapted task scheduling strategy for WSNs is presented. First, a multi-agent-based architecture for WSNs is proposed and a mathematical model of dynamic alliance is constructed for the task allocation problem. Then an effective discrete particle swarm optimization (PSO) algorithm for the dynamic alliance (DPSO-DA) with a well-designed particle position code and fitness function is proposed. A mutation operator which can effectively improve the algorithm’s ability of global search and population diversity is also introduced in this algorithm. Finally, the simulation results show that the proposed solution can achieve significant better performance than other algorithms. PMID:22163971

Brain-computer interface control along instructed paths

NASA Astrophysics Data System (ADS)

Sadtler, P. T.; Ryu, S. I.; Tyler-Kabara, E. C.; Yu, B. M.; Batista, A. P.

2015-02-01

Objective. Brain-computer interfaces (BCIs) are being developed to assist paralyzed people and amputees by translating neural activity into movements of a computer cursor or prosthetic limb. Here we introduce a novel BCI task paradigm, intended to help accelerate improvements to BCI systems. Through this task, we can push the performance limits of BCI systems, we can quantify more accurately how well a BCI system captures the user’s intent, and we can increase the richness of the BCI movement repertoire. Approach. We have implemented an instructed path task, wherein the user must drive a cursor along a visible path. The instructed path task provides a versatile framework to increase the difficulty of the task and thereby push the limits of performance. Relative to traditional point-to-point tasks, the instructed path task allows more thorough analysis of decoding performance and greater richness of movement kinematics. Main results. We demonstrate that monkeys are able to perform the instructed path task in a closed-loop BCI setting. We further investigate how the performance under BCI control compares to native arm control, whether users can decrease their movement variability in the face of a more demanding task, and how the kinematic richness is enhanced in this task. Significance. The use of the instructed path task has the potential to accelerate the development of BCI systems and their clinical translation.

A quantitative measure for degree of automation and its relation to system performance and mental load.

PubMed

Wei, Z G; Macwan, A P; Wieringa, P A

1998-06-01

In this paper we quantitatively model degree of automation (DofA) in supervisory control as a function of the number and nature of tasks to be performed by the operator and automation. This model uses a task weighting scheme in which weighting factors are obtained from task demand load, task mental load, and task effect on system performance. The computation of DofA is demonstrated using an experimental system. Based on controlled experiments using operators, analyses of the task effect on system performance, the prediction and assessment of task demand load, and the prediction of mental load were performed. Each experiment had a different DofA. The effect of a change in DofA on system performance and mental load was investigated. It was found that system performance became less sensitive to changes in DofA at higher levels of DofA. The experimental data showed that when the operator controlled a partly automated system, perceived mental load could be predicted from the task mental load for each task component, as calculated by analyzing a situation in which all tasks were manually controlled. Actual or potential applications of this research include a methodology to balance and optimize the automation of complex industrial systems.

Application of a COTS Resource Optimization Framework to the SSN Sensor Tasking Domain - Part I: Problem Definition

NASA Astrophysics Data System (ADS)

Tran, T.

With the onset of the SmallSat era, the RSO catalog is expected to see continuing growth in the near future. This presents a significant challenge to the current sensor tasking of the SSN. The Air Force is in need of a sensor tasking system that is robust, efficient, scalable, and able to respond in real-time to interruptive events that can change the tracking requirements of the RSOs. Furthermore, the system must be capable of using processed data from heterogeneous sensors to improve tasking efficiency. The SSN sensor tasking can be regarded as an economic problem of supply and demand: the amount of tracking data needed by each RSO represents the demand side while the SSN sensor tasking represents the supply side. As the number of RSOs to be tracked grows, demand exceeds supply. The decision-maker is faced with the problem of how to allocate resources in the most efficient manner. Braxton recently developed a framework called Multi-Objective Resource Optimization using Genetic Algorithm (MOROUGA) as one of its modern COTS software products. This optimization framework took advantage of the maturing technology of evolutionary computation in the last 15 years. This framework was applied successfully to address the resource allocation of an AFSCN-like problem. In any resource allocation problem, there are five key elements: (1) the resource pool, (2) the tasks using the resources, (3) a set of constraints on the tasks and the resources, (4) the objective functions to be optimized, and (5) the demand levied on the resources. In this paper we explain in detail how the design features of this optimization framework are directly applicable to address the SSN sensor tasking domain. We also discuss our validation effort as well as present the result of the AFSCN resource allocation domain using a prototype based on this optimization framework.

The wandering self: Tracking distracting self-generated thought in a cognitively demanding context.

PubMed

Huijser, Stefan; van Vugt, Marieke K; Taatgen, Niels A

2018-02-01

We investigated how self-referential processing (SRP) affected self-generated thought in a complex working memory task (CWM) to test the predictions of a computational cognitive model. This model described self-generated thought as resulting from competition between task- and distracting processes, and predicted that self-generated thought interferes with rehearsal, reducing memory performance. SRP was hypothesized to influence this goal competition process by encouraging distracting self-generated thinking. We used a spatial CWM task to examine if SRP instigated such thoughts, and employed eye-tracking to examine rehearsal interference in eye-movement and self-generated thinking in pupil size. The results showed that SRP was associated with lower performance and higher rates of self-generated thought. Self-generated thought was associated with less rehearsal and we observed a smaller pupil size for mind wandering. We conclude that SRP can instigate self-generated thought and that goal competition provides a likely explanation for how self-generated thoughts arises in a demanding task. Copyright © 2017 Elsevier Inc. All rights reserved.

Enterprise Cloud Architecture for Chinese Ministry of Railway

NASA Astrophysics Data System (ADS)

Shan, Xumei; Liu, Hefeng

Enterprise like PRC Ministry of Railways (MOR), is facing various challenges ranging from highly distributed computing environment and low legacy system utilization, Cloud Computing is increasingly regarded as one workable solution to address this. This article describes full scale cloud solution with Intel Tashi as virtual machine infrastructure layer, Hadoop HDFS as computing platform, and self developed SaaS interface, gluing virtual machine and HDFS with Xen hypervisor. As a result, on demand computing task application and deployment have been tackled per MOR real working scenarios at the end of article.

Associative Encoding and Retrieval Are Predicted by Functional Connectivity in Distinct Hippocampal Area CA1 Pathways

PubMed Central

Duncan, Katherine; Tompary, Alexa

2014-01-01

Determining how the hippocampus supports the unique demands of memory encoding and retrieval is fundamental for understanding the biological basis of episodic memory. One possibility proposed by theoretical models is that the distinct computational demands of encoding and retrieval are accommodated by shifts in the functional interaction between the hippocampal CA1 subregion and its input structures. However, empirical tests of this hypothesis are lacking. To test this in humans, we used high-resolution fMRI to measure functional connectivity between hippocampal area CA1 and regions of the medial temporal lobe and midbrain during extended blocks of associative encoding and retrieval tasks. We found evidence for a double dissociation between the pathways supporting successful encoding and retrieval. Specifically, during the associative encoding task, but not the retrieval task, functional connectivity only between area CA1 and the ventral tegmental area predicted associative long-term memory. In contrast, connectivity between area CA1 and DG/CA3 was greater, on average, during the retrieval task compared with the encoding task, and, importantly, the strength of this connectivity significantly correlated with retrieval success. Together, these findings serve as an important first step toward understanding how the demands of fundamental memory processes may be met by changes in the relative strength of connectivity within hippocampal pathways. PMID:25143600

Dual tasking and stuttering: from the laboratory to the clinic.

PubMed

Metten, Christine; Bosshardt, Hans-Georg; Jones, Mark; Eisenhuth, John; Block, Susan; Carey, Brenda; O'Brian, Sue; Packman, Ann; Onslow, Mark; Menzies, Ross

2011-01-01

The aim of the three studies in this article was to develop a way to include dual tasking in speech restructuring treatment for persons who stutter (PWS). It is thought that this may help clients maintain the benefits of treatment in the real world, where attentional resources are frequently diverted away from controlling fluency by the demands of other tasks. In Part 1, 17 PWS performed a story-telling task and a computer semantic task simultaneously. Part 2 reports the incorporation of the Part 1 protocol into a handy device for use in a clinical setting (the Dual Task and Stuttering Device, DAS-D). Part 3 is a proof of concept study in which three PWS reported on their experiences of using the device during treatment. In Part 1, stuttering frequency and errors on the computer task both increased under dual task conditions, indicating that the protocol would be appropriate for use in a clinical setting. All three participants in Part 3 reported positively on their experiences using the DAS-D. Dual tasking during treatment using the DAS-D appears to be a viable clinical procedure. Further research is required to establish effectiveness.

The role of metacognition in prospective memory: anticipated task demands influence attention allocation strategies.

PubMed

Rummel, Jan; Meiser, Thorsten

2013-09-01

The present study investigates how individuals distribute their attentional resources between a prospective memory task and an ongoing task. Therefore, metacognitive expectations about the attentional demands of the prospective-memory task were manipulated while the factual demands were held constant. In Experiments 1a and 1b, we found attentional costs from a prospective-memory task with low factual demands to be significantly reduced when information about the low to-be-expected demands were provided, while prospective-memory performance remained largely unaffected. In Experiment 2, attentional monitoring in a more demanding prospective-memory task also varied with information about the to-be-expected demands (high vs. low) and again there were no equivalent changes in prospective-memory performance. These findings suggest that attention-allocation strategies of prospective memory rely on metacognitive expectations about prospective-memory task demands. Furthermore, the results suggest that attentional monitoring is only functional for prospective memory to the extent to which anticipated task demands reflect objective task demands. Copyright © 2013 Elsevier Inc. All rights reserved.

Software designs of image processing tasks with incremental refinement of computation.

PubMed

Anastasia, Davide; Andreopoulos, Yiannis

2010-08-01

Software realizations of computationally-demanding image processing tasks (e.g., image transforms and convolution) do not currently provide graceful degradation when their clock-cycles budgets are reduced, e.g., when delay deadlines are imposed in a multitasking environment to meet throughput requirements. This is an important obstacle in the quest for full utilization of modern programmable platforms' capabilities since worst-case considerations must be in place for reasonable quality of results. In this paper, we propose (and make available online) platform-independent software designs performing bitplane-based computation combined with an incremental packing framework in order to realize block transforms, 2-D convolution and frame-by-frame block matching. The proposed framework realizes incremental computation: progressive processing of input-source increments improves the output quality monotonically. Comparisons with the equivalent nonincremental software realization of each algorithm reveal that, for the same precision of the result, the proposed approach can lead to comparable or faster execution, while it can be arbitrarily terminated and provide the result up to the computed precision. Application examples with region-of-interest based incremental computation, task scheduling per frame, and energy-distortion scalability verify that our proposal provides significant performance scalability with graceful degradation.

Earth Science Informatics Comes of Age

NASA Technical Reports Server (NTRS)

Jodha, Siri; Khalsa, S.; Ramachandran, Rahul

2014-01-01

The volume and complexity of Earth science data have steadily increased, placing ever-greater demands on researchers, software developers and data managers tasked with handling such data. Additional demands arise from requirements being levied by funding agencies and governments to better manage, preserve and provide open access to data. Fortunately, over the past 10-15 years significant advances in information technology, such as increased processing power, advanced programming languages, more sophisticated and practical standards, and near-ubiquitous internet access have made the jobs of those acquiring, processing, distributing and archiving data easier. These advances have also led to an increasing number of individuals entering the field of informatics as it applies to Geoscience and Remote Sensing. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of data, information, and knowledge. Informatics also encompasses the use of computers and computational methods to support decisionmaking and other applications for societal benefits.

From photons to big-data applications: terminating terabits

PubMed Central

2016-01-01

Computer architectures have entered a watershed as the quantity of network data generated by user applications exceeds the data-processing capacity of any individual computer end-system. It will become impossible to scale existing computer systems while a gap grows between the quantity of networked data and the capacity for per system data processing. Despite this, the growth in demand in both task variety and task complexity continues unabated. Networked computer systems provide a fertile environment in which new applications develop. As networked computer systems become akin to infrastructure, any limitation upon the growth in capacity and capabilities becomes an important constraint of concern to all computer users. Considering a networked computer system capable of processing terabits per second, as a benchmark for scalability, we critique the state of the art in commodity computing, and propose a wholesale reconsideration in the design of computer architectures and their attendant ecosystem. Our proposal seeks to reduce costs, save power and increase performance in a multi-scale approach that has potential application from nanoscale to data-centre-scale computers. PMID:26809573

From photons to big-data applications: terminating terabits.

PubMed

Zilberman, Noa; Moore, Andrew W; Crowcroft, Jon A

2016-03-06

Computer architectures have entered a watershed as the quantity of network data generated by user applications exceeds the data-processing capacity of any individual computer end-system. It will become impossible to scale existing computer systems while a gap grows between the quantity of networked data and the capacity for per system data processing. Despite this, the growth in demand in both task variety and task complexity continues unabated. Networked computer systems provide a fertile environment in which new applications develop. As networked computer systems become akin to infrastructure, any limitation upon the growth in capacity and capabilities becomes an important constraint of concern to all computer users. Considering a networked computer system capable of processing terabits per second, as a benchmark for scalability, we critique the state of the art in commodity computing, and propose a wholesale reconsideration in the design of computer architectures and their attendant ecosystem. Our proposal seeks to reduce costs, save power and increase performance in a multi-scale approach that has potential application from nanoscale to data-centre-scale computers. © 2016 The Authors.

The relationship between mathematics and language: academic implications for children with specific language impairment and English language learners.

PubMed

Alt, Mary; Arizmendi, Genesis D; Beal, Carole R

2014-07-01

The present study examined the relationship between mathematics and language to better understand the nature of the deficit and the academic implications associated with specific language impairment (SLI) and academic implications for English language learners (ELLs). School-age children (N = 61; 20 SLI, 20 ELL, 21 native monolingual English [NE]) were assessed using a norm-referenced mathematics instrument and 3 experimental computer-based mathematics games that varied in language demands. Group means were compared with analyses of variance. The ELL group was less accurate than the NE group only when tasks were language heavy. In contrast, the group with SLI was less accurate than the groups with NE and ELLs on language-heavy tasks and some language-light tasks. Specifically, the group with SLI was less accurate on tasks that involved comparing numerical symbols and using visual working memory for patterns. However, there were no group differences between children with SLI and peers without SLI on language-light mathematics tasks that involved visual working memory for numerical symbols. Mathematical difficulties of children who are ELLs appear to be related to the language demands of mathematics tasks. In contrast, children with SLI appear to have difficulty with mathematics tasks because of linguistic as well as nonlinguistic processing constraints.

The “Silent Dog” Method: Analyzing the Impact of Self-Generated Rules When Teaching Different Computer Chains to Boys with Autism

PubMed Central

Arntzen, Erik; Halstadtro, Lill-Beathe; Halstadtro, Monica

2009-01-01

The purpose of the study was to extend the literature on verbal self-regulation by using the “silent dog” method to evaluate the role of verbal regulation over nonverbal behavior in 2 individuals with autism. Participants were required to talk-aloud while performing functional computer tasks.Then the effects of distracters with increasing demands on target behavior were evaluated as well as whether self-talk emitted by Participant 1 could be used to alter Participant 2's performance. Results suggest that participants' tasks seemed to be under control of self-instructions, and the rules generated from Participants 1's self-talk were effective in teaching computer skills to Participant 2. The silent dog method was useful in evaluating the possible role of self-generated rules in teaching computer skills to participants with autism. PMID:22477428

The "silent dog" method: analyzing the impact of self-generated rules when teaching different computer chains to boys with autism.

PubMed

Arntzen, Erik; Halstadtro, Lill-Beathe; Halstadtro, Monica

2009-01-01

The purpose of the study was to extend the literature on verbal self-regulation by using the "silent dog" method to evaluate the role of verbal regulation over nonverbal behavior in 2 individuals with autism. Participants were required to talk-aloud while performing functional computer tasks.Then the effects of distracters with increasing demands on target behavior were evaluated as well as whether self-talk emitted by Participant 1 could be used to alter Participant 2's performance. Results suggest that participants' tasks seemed to be under control of self-instructions, and the rules generated from Participants 1's self-talk were effective in teaching computer skills to Participant 2. The silent dog method was useful in evaluating the possible role of self-generated rules in teaching computer skills to participants with autism.

U.S. Army physical demands study: Prevalence and frequency of performing physically demanding tasks in deployed and non-deployed settings.

PubMed

Boye, Michael W; Cohen, Bruce S; Sharp, Marilyn A; Canino, Maria C; Foulis, Stephen A; Larcom, Kathleen; Smith, Laurel

2017-11-01

To compare percentages of on-duty time spent performing physically demanding soldier tasks in non-deployed and deployed settings, and secondarily examine the number of physically demanding tasks performed among five Army combat arms occupational specialties. Job task analysis. Soldiers (n=1295; over 99% serving on active duty) across five Army jobs completed one of three questionnaires developed using reviews of job and task related documents, input from subject matter experts, observation of task performance, and conduct of focus groups. Soldiers reported estimates of the total on-duty time spent performing physically demanding tasks in both deployed and non-deployed settings. One-way analyses of variance and Duncan post-hoc tests were used to compare percentage time differences by job. Two-tailed t-tests were used to evaluate differences by setting. Frequency analyses were used to present supplementary findings. Soldiers reported performing physically demanding job-specific tasks 17.7% of the time while non-deployed and 19.6% of the time while deployed. There were significant differences in time spent on job-specific tasks across settings (p<0.05) for three of five occupational specialties. When categories of physically demanding tasks were grouped, all soldiers reported spending more time on physically demanding tasks when deployed (p<0.001). Twenty-five percent reported performing less than half the physically demanding tasks represented on the questionnaire in the last two years. Soldiers spent more time performing physically demanding tasks while deployed compared to non-deployed but spent similar amounts of time performing job-specific tasks. Published by Elsevier Ltd.

Fault tolerant architectures for integrated aircraft electronics systems, task 2

NASA Technical Reports Server (NTRS)

Levitt, K. N.; Melliar-Smith, P. M.; Schwartz, R. L.

1984-01-01

The architectural basis for an advanced fault tolerant on-board computer to succeed the current generation of fault tolerant computers is examined. The network error tolerant system architecture is studied with particular attention to intercluster configurations and communication protocols, and to refined reliability estimates. The diagnosis of faults, so that appropriate choices for reconfiguration can be made is discussed. The analysis relates particularly to the recognition of transient faults in a system with tasks at many levels of priority. The demand driven data-flow architecture, which appears to have possible application in fault tolerant systems is described and work investigating the feasibility of automatic generation of aircraft flight control programs from abstract specifications is reported.

GATECloud.net: a platform for large-scale, open-source text processing on the cloud.

PubMed

Tablan, Valentin; Roberts, Ian; Cunningham, Hamish; Bontcheva, Kalina

2013-01-28

Cloud computing is increasingly being regarded as a key enabler of the 'democratization of science', because on-demand, highly scalable cloud computing facilities enable researchers anywhere to carry out data-intensive experiments. In the context of natural language processing (NLP), algorithms tend to be complex, which makes their parallelization and deployment on cloud platforms a non-trivial task. This study presents a new, unique, cloud-based platform for large-scale NLP research--GATECloud. net. It enables researchers to carry out data-intensive NLP experiments by harnessing the vast, on-demand compute power of the Amazon cloud. Important infrastructural issues are dealt with by the platform, completely transparently for the researcher: load balancing, efficient data upload and storage, deployment on the virtual machines, security and fault tolerance. We also include a cost-benefit analysis and usage evaluation.

A survey of GPU-based medical image computing techniques

PubMed Central

Shi, Lin; Liu, Wen; Zhang, Heye; Xie, Yongming

2012-01-01

Medical imaging currently plays a crucial role throughout the entire clinical applications from medical scientific research to diagnostics and treatment planning. However, medical imaging procedures are often computationally demanding due to the large three-dimensional (3D) medical datasets to process in practical clinical applications. With the rapidly enhancing performances of graphics processors, improved programming support, and excellent price-to-performance ratio, the graphics processing unit (GPU) has emerged as a competitive parallel computing platform for computationally expensive and demanding tasks in a wide range of medical image applications. The major purpose of this survey is to provide a comprehensive reference source for the starters or researchers involved in GPU-based medical image processing. Within this survey, the continuous advancement of GPU computing is reviewed and the existing traditional applications in three areas of medical image processing, namely, segmentation, registration and visualization, are surveyed. The potential advantages and associated challenges of current GPU-based medical imaging are also discussed to inspire future applications in medicine. PMID:23256080

Demand curves for hypothetical cocaine in cocaine-dependent individuals.

PubMed

Bruner, Natalie R; Johnson, Matthew W

2014-03-01

Drug purchasing tasks have been successfully used to examine demand for hypothetical consumption of abused drugs including heroin, nicotine, and alcohol. In these tasks, drug users make hypothetical choices whether to buy drugs, and if so, at what quantity, at various potential prices. These tasks allow for behavioral economic assessment of that drug's intensity of demand (preferred level of consumption at extremely low prices) and demand elasticity (sensitivity of consumption to price), among other metrics. However, a purchasing task for cocaine in cocaine-dependent individuals has not been investigated. This study examined a novel Cocaine Purchasing Task and the relation between resulting demand metrics and self-reported cocaine use data. Participants completed a questionnaire assessing hypothetical purchases of cocaine units at prices ranging from $0.01 to $1,000. Demand curves were generated from responses on the Cocaine Purchasing Task. Correlations compared metrics from the demand curve to measures of real-world cocaine use. Group and individual data were well modeled by a demand curve function. The validity of the Cocaine Purchasing Task was supported by a significant correlation between the demand curve metrics of demand intensity and O max (determined from Cocaine Purchasing Task data) and self-reported measures of cocaine use. Partial correlations revealed that after controlling for demand intensity, demand elasticity and the related measure, P max, were significantly correlated with real-world cocaine use. Results indicate that the Cocaine Purchasing Task produces orderly demand curve data, and that these data relate to real-world measures of cocaine use.

A matrix for the qualitative evaluation of nursing tasks.

PubMed

Durosaiye, Isaiah O; Hadjri, Karim; Liyanage, Champika L; Bennett, Kina

2018-04-01

To formulate a model for patient-nurse interaction; to compile a comprehensive list of nursing tasks on hospital wards; and to construct a nursing tasks demand matrix. The physical demands associated with nursing profession are of growing interest among researchers. Yet, it is the complexity of nursing tasks that defines the demands of ward nurses' role. This study explores nursing tasks, based on patient-nurse interaction on hospital wards. Extant literature was reviewed to formulate a patient-nurse interaction model. Twenty ward nurses were interviewed to compile a list of nursing tasks. These nursing tasks were mapped against the patient-nurse interaction model. A patient-nurse interaction model was created, consisting of: (1) patient care, (2) patient surveillance and (3) patient support. Twenty-three nursing tasks were identified. The nursing tasks demand matrix was constructed. Ward managers may use a nursing tasks demand matrix to determine the demands of nursing tasks on ward nurses. While many studies have explored either the physical or the psychosocial aspects of nursing tasks separately, this study suggests that the physicality of nursing tasks must be evaluated in tandem with their complexity. Ward managers may take a holistic approach to nursing tasks evaluation by using a nursing tasks demand matrix. © 2017 John Wiley & Sons Ltd.

Task-dependent individual differences in prefrontal connectivity.

PubMed

Biswal, Bharat B; Eldreth, Dana A; Motes, Michael A; Rypma, Bart

2010-09-01

Recent advances in neuroimaging have permitted testing of hypotheses regarding the neural bases of individual differences, but this burgeoning literature has been characterized by inconsistent results. To test the hypothesis that differences in task demands could contribute to between-study variability in brain-behavior relationships, we had participants perform 2 tasks that varied in the extent of cognitive involvement. We examined connectivity between brain regions during a low-demand vigilance task and a higher-demand digit-symbol visual search task using Granger causality analysis (GCA). Our results showed 1) Significant differences in numbers of frontoparietal connections between low- and high-demand tasks 2) that GCA can detect activity changes that correspond with task-demand changes, and 3) faster participants showed more vigilance-related activity than slower participants, but less visual-search activity. These results suggest that relatively low-demand cognitive performance depends on spontaneous bidirectionally fluctuating network activity, whereas high-demand performance depends on a limited, unidirectional network. The nature of brain-behavior relationships may vary depending on the extent of cognitive demand. High-demand network activity may reflect the extent to which individuals require top-down executive guidance of behavior for successful task performance. Low-demand network activity may reflect task- and performance monitoring that minimizes executive requirements for guidance of behavior.

Task-Dependent Individual Differences in Prefrontal Connectivity

PubMed Central

Biswal, Bharat B.; Eldreth, Dana A.; Motes, Michael A.

2010-01-01

Recent advances in neuroimaging have permitted testing of hypotheses regarding the neural bases of individual differences, but this burgeoning literature has been characterized by inconsistent results. To test the hypothesis that differences in task demands could contribute to between-study variability in brain-behavior relationships, we had participants perform 2 tasks that varied in the extent of cognitive involvement. We examined connectivity between brain regions during a low-demand vigilance task and a higher-demand digit–symbol visual search task using Granger causality analysis (GCA). Our results showed 1) Significant differences in numbers of frontoparietal connections between low- and high-demand tasks 2) that GCA can detect activity changes that correspond with task-demand changes, and 3) faster participants showed more vigilance-related activity than slower participants, but less visual-search activity. These results suggest that relatively low-demand cognitive performance depends on spontaneous bidirectionally fluctuating network activity, whereas high-demand performance depends on a limited, unidirectional network. The nature of brain-behavior relationships may vary depending on the extent of cognitive demand. High-demand network activity may reflect the extent to which individuals require top-down executive guidance of behavior for successful task performance. Low-demand network activity may reflect task- and performance monitoring that minimizes executive requirements for guidance of behavior. PMID:20064942

Parietal neural prosthetic control of a computer cursor in a graphical-user-interface task

NASA Astrophysics Data System (ADS)

Revechkis, Boris; Aflalo, Tyson NS; Kellis, Spencer; Pouratian, Nader; Andersen, Richard A.

2014-12-01

Objective. To date, the majority of Brain-Machine Interfaces have been used to perform simple tasks with sequences of individual targets in otherwise blank environments. In this study we developed a more practical and clinically relevant task that approximated modern computers and graphical user interfaces (GUIs). This task could be problematic given the known sensitivity of areas typically used for BMIs to visual stimuli, eye movements, decision-making, and attentional control. Consequently, we sought to assess the effect of a complex, GUI-like task on the quality of neural decoding. Approach. A male rhesus macaque monkey was implanted with two 96-channel electrode arrays in area 5d of the superior parietal lobule. The animal was trained to perform a GUI-like ‘Face in a Crowd’ task on a computer screen that required selecting one cued, icon-like, face image from a group of alternatives (the ‘Crowd’) using a neurally controlled cursor. We assessed whether the crowd affected decodes of intended cursor movements by comparing it to a ‘Crowd Off’ condition in which only the matching target appeared without alternatives. We also examined if training a neural decoder with the Crowd On rather than Off had any effect on subsequent decode quality. Main results. Despite the additional demands of working with the Crowd On, the animal was able to robustly perform the task under Brain Control. The presence of the crowd did not itself affect decode quality. Training the decoder with the Crowd On relative to Off had no negative influence on subsequent decoding performance. Additionally, the subject was able to gaze around freely without influencing cursor position. Significance. Our results demonstrate that area 5d recordings can be used for decoding in a complex, GUI-like task with free gaze. Thus, this area is a promising source of signals for neural prosthetics that utilize computing devices with GUI interfaces, e.g. personal computers, mobile devices, and tablet computers.

Parietal neural prosthetic control of a computer cursor in a graphical-user-interface task.

PubMed

Revechkis, Boris; Aflalo, Tyson N S; Kellis, Spencer; Pouratian, Nader; Andersen, Richard A

2014-12-01

To date, the majority of Brain-Machine Interfaces have been used to perform simple tasks with sequences of individual targets in otherwise blank environments. In this study we developed a more practical and clinically relevant task that approximated modern computers and graphical user interfaces (GUIs). This task could be problematic given the known sensitivity of areas typically used for BMIs to visual stimuli, eye movements, decision-making, and attentional control. Consequently, we sought to assess the effect of a complex, GUI-like task on the quality of neural decoding. A male rhesus macaque monkey was implanted with two 96-channel electrode arrays in area 5d of the superior parietal lobule. The animal was trained to perform a GUI-like 'Face in a Crowd' task on a computer screen that required selecting one cued, icon-like, face image from a group of alternatives (the 'Crowd') using a neurally controlled cursor. We assessed whether the crowd affected decodes of intended cursor movements by comparing it to a 'Crowd Off' condition in which only the matching target appeared without alternatives. We also examined if training a neural decoder with the Crowd On rather than Off had any effect on subsequent decode quality. Despite the additional demands of working with the Crowd On, the animal was able to robustly perform the task under Brain Control. The presence of the crowd did not itself affect decode quality. Training the decoder with the Crowd On relative to Off had no negative influence on subsequent decoding performance. Additionally, the subject was able to gaze around freely without influencing cursor position. Our results demonstrate that area 5d recordings can be used for decoding in a complex, GUI-like task with free gaze. Thus, this area is a promising source of signals for neural prosthetics that utilize computing devices with GUI interfaces, e.g. personal computers, mobile devices, and tablet computers.

Aging and the Vulnerability of Speech to Dual Task Demands

PubMed Central

Kemper, Susan; Schmalzried, RaLynn; Hoffman, Lesa; Herman, Ruth

2010-01-01

Tracking a digital pursuit rotor task was used to measure dual task costs of language production by young and older adults. Tracking performance by both groups was affected by dual task demands: time on target declined and tracking error increased as dual task demands increased from the baseline condition to a moderately demanding dual task condition to a more demanding dual task condition. When dual task demands were moderate, older adults’ speech rate declined but their fluency, grammatical complexity, and content were unaffected. When the dual task was more demanding, older adults’ speech, like young adults’ speech, became highly fragmented, ungrammatical, and incoherent. Vocabulary, working memory, processing speed, and inhibition affected vulnerability to dual task costs: vocabulary provided some protection for sentence length and grammaticality, working memory conferred some protection for grammatical complexity, and processing speed provided some protection for speech rate, propositional density, coherence, and lexical diversity. Further, vocabulary and working memory capacity provided more protection for older adults than for young adults although the protective effect of processing speed was somewhat reduced for older adults as compared to the young adults. PMID:21186917

High Skills Utilisation under Mass Higher Education: Graduate Employment in Service Industries in Britain.

ERIC Educational Resources Information Center

Mason, Geoff

2002-01-01

In Britain, the retailing, computer services, transportation, and communications industries have hired increasing numbers of college graduates, both because of demand for skills and oversupply of graduates. This has contributed to temporary and permanent job upgrading through expansion of tasks and responsibilities in certain jobs. (Contains 14…

Demand Curves for Hypothetical Cocaine in Cocaine-Dependent Individuals

PubMed Central

Bruner, Natalie R.; Johnson, Matthew W.

2013-01-01

Rationale Drug purchasing tasks have been successfully used to examine demand for hypothetical consumption of abused drugs including heroin, nicotine, and alcohol. In these tasks drug users make hypothetical choices whether to buy drugs, and if so, at what quantity, at various potential prices. These tasks allow for behavioral economic assessment of that drug's intensity of demand (preferred level of consumption at extremely low prices) and demand elasticity (sensitivity of consumption to price), among other metrics. However, a purchasing task for cocaine in cocaine-dependent individuals has not been investigated. Objectives This study examined a novel Cocaine Purchasing Task and the relation between resulting demand metrics and self-reported cocaine use data. Methods Participants completed a questionnaire assessing hypothetical purchases of cocaine units at prices ranging from $0.01 to $1,000. Demand curves were generated from responses on the Cocaine Purchasing Task. Correlations compared metrics from the demand curve to measures of real-world cocaine use. Results Group and individual data were well modeled by a demand curve function. The validity of the Cocaine Purchasing Task was supported by a significant correlation between the demand curve metrics of demand intensity and Omax (determined from Cocaine Purchasing Task data) and self-reported measures of cocaine use. Partial correlations revealed that after controlling for demand intensity, demand elasticity and the related measure, Pmax, were significantly correlated with real-world cocaine use. Conclusions Results indicate that the Cocaine Purchasing Task produces orderly demand curve data, and that these data relate to real-world measures of cocaine use. PMID:24217899

Different strategies in solving series completion inductive reasoning problems: an fMRI and computational study.

PubMed

Liang, Peipeng; Jia, Xiuqin; Taatgen, Niels A; Zhong, Ning; Li, Kuncheng

2014-08-01

Neural correlate of human inductive reasoning process is still unclear. Number series and letter series completion are two typical inductive reasoning tasks, and with a common core component of rule induction. Previous studies have demonstrated that different strategies are adopted in number series and letter series completion tasks; even the underlying rules are identical. In the present study, we examined cortical activation as a function of two different reasoning strategies for solving series completion tasks. The retrieval strategy, used in number series completion tasks, involves direct retrieving of arithmetic knowledge to get the relations between items. The procedural strategy, used in letter series completion tasks, requires counting a certain number of times to detect the relations linking two items. The two strategies require essentially the equivalent cognitive processes, but have different working memory demands (the procedural strategy incurs greater demands). The procedural strategy produced significant greater activity in areas involved in memory retrieval (dorsolateral prefrontal cortex, DLPFC) and mental representation/maintenance (posterior parietal cortex, PPC). An ACT-R model of the tasks successfully predicted behavioral performance and BOLD responses. The present findings support a general-purpose dual-process theory of inductive reasoning regarding the cognitive architecture. Copyright © 2014 Elsevier B.V. All rights reserved.

Workload and Performance in Air Traffic Control: Exploring the Influence of Levels of Automation and Variation in Task Demand

NASA Technical Reports Server (NTRS)

Edwards, Tamsyn El; Martin, Lynne; Bienert, Nancy; Mercer, Joey

2017-01-01

In air traffic control, task demand and workload have important implications for the safety and efficiency of air traffic. Task demand is dynamic, however, research on demand transitions and associated controller perception and performance is limited. In addition, there is a comparatively restricted understanding of the influence of task demand transitions on workload and performance, in association with automation. This study used an air traffic control simulation to investigate the influence of task demand transitions and two conditions of varying automation, on workload and efficiency-related performance. Findings showed that a both the direction of the task demand variation, and the amount of automation, influenced the relationship between workload and performance. Further research is needed to enhance understanding of demand transition and workload history effects on operator experience and performance, in both air traffic control and other safety-critical domains.

Petri nets as a modeling tool for discrete concurrent tasks of the human operator. [describing sequential and parallel demands on human operators

NASA Technical Reports Server (NTRS)

Schumacher, W.; Geiser, G.

1978-01-01

The basic concepts of Petri nets are reviewed as well as their application as the fundamental model of technical systems with concurrent discrete events such as hardware systems and software models of computers. The use of Petri nets is proposed for modeling the human operator dealing with concurrent discrete tasks. Their properties useful in modeling the human operator are discussed and practical examples are given. By means of and experimental investigation of binary concurrent tasks which are presented in a serial manner, the representation of human behavior by Petri nets is demonstrated.

Interactive Light Stimulus Generation with High Performance Real-Time Image Processing and Simple Scripting.

PubMed

Szécsi, László; Kacsó, Ágota; Zeck, Günther; Hantz, Péter

2017-01-01

Light stimulation with precise and complex spatial and temporal modulation is demanded by a series of research fields like visual neuroscience, optogenetics, ophthalmology, and visual psychophysics. We developed a user-friendly and flexible stimulus generating framework (GEARS GPU-based Eye And Retina Stimulation Software), which offers access to GPU computing power, and allows interactive modification of stimulus parameters during experiments. Furthermore, it has built-in support for driving external equipment, as well as for synchronization tasks, via USB ports. The use of GEARS does not require elaborate programming skills. The necessary scripting is visually aided by an intuitive interface, while the details of the underlying software and hardware components remain hidden. Internally, the software is a C++/Python hybrid using OpenGL graphics. Computations are performed on the GPU, and are defined in the GLSL shading language. However, all GPU settings, including the GPU shader programs, are automatically generated by GEARS. This is configured through a method encountered in game programming, which allows high flexibility: stimuli are straightforwardly composed using a broad library of basic components. Stimulus rendering is implemented solely in C++, therefore intermediary libraries for interfacing could be omitted. This enables the program to perform computationally demanding tasks like en-masse random number generation or real-time image processing by local and global operations.

Accommodation in Astigmatic Children During Visual Task Performance

PubMed Central

Harvey, Erin M.; Miller, Joseph M.; Apple, Howard P.; Parashar, Pavan; Twelker, J. Daniel; Crescioni, Mabel; Davis, Amy L.; Leonard-Green, Tina K.; Campus, Irene; Sherrill, Duane L.

2014-01-01

Purpose. To determine the accuracy and stability of accommodation in uncorrected children during visual task performance. Methods. Subjects were second- to seventh-grade children from a highly astigmatic population. Measurements of noncycloplegic right eye spherical equivalent (Mnc) were obtained while uncorrected subjects performed three visual tasks at near (40 cm) and distance (2 m). Tasks included reading sentences with stimulus letter size near acuity threshold and an age-appropriate letter size (high task demands) and viewing a video (low task demand). Repeated measures ANOVA assessed the influence of astigmatism, task demand, and accommodative demand on accuracy (mean Mnc) and variability (mean SD of Mnc) of accommodation. Results. For near and distance analyses, respectively, sample size was 321 and 247, mean age was 10.37 (SD 1.77) and 10.30 (SD 1.74) years, mean cycloplegic M was 0.48 (SD 1.10) and 0.79 diopters (D) (SD 1.00), and mean astigmatism was 0.99 (SD 1.15) and 0.75 D (SD 0.96). Poor accommodative accuracy was associated with high astigmatism, low task demand (video viewing), and high accommodative demand. The negative effect of accommodative demand on accuracy increased with increasing astigmatism, with the poorest accommodative accuracy observed in high astigmats (≥3.00 D) with high accommodative demand/high hyperopia (1.53 D and 2.05 D of underaccommodation for near and distant stimuli, respectively). Accommodative variability was greatest in high astigmats and was uniformly high across task condition. No/low and moderate astigmats showed higher variability for the video task than the reading tasks. Conclusions. Accuracy of accommodation is reduced in uncorrected children with high astigmatism and high accommodative demand/high hyperopia, but improves with increased visual task demand (reading). High astigmats showed the greatest variability in accommodation. PMID:25103265

Scheduling quality of precise form sets which consist of tasks of circular type in GRID systems

NASA Astrophysics Data System (ADS)

Saak, A. E.; Kureichik, V. V.; Kravchenko, Y. A.

2018-05-01

Users’ demand in computer power and rise of technology favour the arrival of Grid systems. The quality of Grid systems’ performance depends on computer and time resources scheduling. Grid systems with a centralized structure of the scheduling system and user’s task are modeled by resource quadrant and re-source rectangle accordingly. A Non-Euclidean heuristic measure, which takes into consideration both the area and the form of an occupied resource region, is used to estimate scheduling quality of heuristic algorithms. The authors use sets, which are induced by the elements of square squaring, as an example of studying the adapt-ability of a level polynomial algorithm with an excess and the one with minimal deviation.

Two-phase strategy of controlling motor coordination determined by task performance optimality.

PubMed

Shimansky, Yury P; Rand, Miya K

2013-02-01

A quantitative model of optimal coordination between hand transport and grip aperture has been derived in our previous studies of reach-to-grasp movements without utilizing explicit knowledge of the optimality criterion or motor plant dynamics. The model's utility for experimental data analysis has been demonstrated. Here we show how to generalize this model for a broad class of reaching-type, goal-directed movements. The model allows for measuring the variability of motor coordination and studying its dependence on movement phase. The experimentally found characteristics of that dependence imply that execution noise is low and does not affect motor coordination significantly. From those characteristics it is inferred that the cost of neural computations required for information acquisition and processing is included in the criterion of task performance optimality as a function of precision demand for state estimation and decision making. The precision demand is an additional optimized control variable that regulates the amount of neurocomputational resources activated dynamically. It is shown that an optimal control strategy in this case comprises two different phases. During the initial phase, the cost of neural computations is significantly reduced at the expense of reducing the demand for their precision, which results in speed-accuracy tradeoff violation and significant inter-trial variability of motor coordination. During the final phase, neural computations and thus motor coordination are considerably more precise to reduce the cost of errors in making a contact with the target object. The generality of the optimal coordination model and the two-phase control strategy is illustrated on several diverse examples.

Computational Modeling of Age-Differences In a Visually Demanding Driving Task: Vehicle Detection

DTIC Science & Technology

1997-10-07

overall estimate of d’ for each scene was calculated from the two levels using the method described in MacMillan and Creelman [13]. MODELING VEHICLE...Scialfa, "Visual and auditory aging," In J. Birren & K. W. Schaie (Eds.) Handbook of the Psychology of Aging (4th edition), 1996, New York: Academic...Computational models of Visual Processing, 1991, Boston MA: MIT Press. [13] N. A. MacMillan & C. D. Creelman , Detection Theory: A User’s Guide, 1991

A Compendium of the Physiological Demands of the 32 Critical Physically Demanding Tasks of Combat Arms Soldiers

DTIC Science & Technology

As part of the U.S. Army Physical Demands Study (which led to the development of the Occupational Physical Assessment Test (OPAT)), 32 physically ...demanding tasks were identified as being critical to combat arms soldiers. In order to identify the most physically demanding of those tests, data were...comprehensive reference of the physiological demands of the critical physically demanding tasks of combat arms Soldiers.

Two-and-a-half-year-olds succeed at a traditional false-belief task with reduced processing demands.

PubMed

Setoh, Peipei; Scott, Rose M; Baillargeon, Renée

2016-11-22

When tested with traditional false-belief tasks, which require answering a standard question about the likely behavior of an agent with a false belief, children perform below chance until age 4 y or later. When tested without such questions, however, children give evidence of false-belief understanding much earlier. Are traditional tasks difficult because they tap a more advanced form of false-belief understanding (fundamental-change view) or because they impose greater processing demands (processing-demands view)? Evidence that young children succeed at traditional false-belief tasks when processing demands are reduced would support the latter view. In prior research, reductions in inhibitory-control demands led to improvements in young children's performance, but often only to chance (instead of below-chance) levels. Here we examined whether further reductions in processing demands might lead to success. We speculated that: (i) young children could respond randomly in a traditional low-inhibition task because their limited information-processing resources are overwhelmed by the total concurrent processing demands in the task; and (ii) these demands include those from the response-generation process activated by the standard question. This analysis suggested that 2.5-y-old toddlers might succeed at a traditional low-inhibition task if response-generation demands were also reduced via practice trials. As predicted, toddlers performed above chance following two response-generation practice trials; toddlers failed when these trials either were rendered less effective or were used in a high-inhibition task. These results support the processing-demands view: Even toddlers succeed at a traditional false-belief task when overall processing demands are reduced.

Stimulus selectivity of drug purchase tasks: A preliminary study evaluating alcohol and cigarette demand.

PubMed

Strickland, Justin C; Stoops, William W

2017-06-01

The use of drug purchase tasks to measure drug demand in human behavioral pharmacology and addiction research has proliferated in recent years. Few studies have systematically evaluated the stimulus selectivity of drug purchase tasks to demonstrate that demand metrics are specific to valuation of or demand for the commodity under study. Stimulus selectivity is broadly defined for this purpose as a condition under which a specific stimulus input or target (e.g., alcohol, cigarettes) is the primary determinant of behavior (e.g., demand). The overall goal of the present study was to evaluate the stimulus selectivity of drug purchase tasks. Participants were sampled from the Amazon.com's crowdsourcing platform Mechanical Turk. Participants completed either alcohol and soda purchase tasks (Experiment 1; N = 139) or cigarette and chocolate purchase tasks (Experiment 2; N = 46), and demand metrics were compared to self-reported use behaviors. Demand metrics for alcohol and soda were closely associated with commodity-similar (e.g., alcohol demand and weekly alcohol use) but not commodity-different (e.g., alcohol demand and weekly soda use) variables. A similar pattern was observed for cigarette and chocolate demand, but selectivity was not as consistent as for alcohol and soda. Collectively, we observed robust selectivity for alcohol and soda purchase tasks and modest selectivity for cigarette and chocolate purchase tasks. These preliminary outcomes suggest that demand metrics adequately reflect the specific commodity under study and support the continued use of purchase tasks in substance use research. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Goal orientation, perceived task outcome and task demands in mathematics tasks: effects on students' attitude in actual task settings.

PubMed

Seegers, Gerard; van Putten, Cornelis M; de Brabander, Cornelis J

2002-09-01

In earlier studies, it has been found that students' domain-specific cognitions and personal learning goals (goal orientation) influence task-specific appraisals of actual learning tasks. The relations between domain-specific and task-specific variables have been specified in the model of adaptive learning. In this study, additional influences, i.e., perceived task outcome on a former occasion and variations in task demands, were investigated. The purpose of this study was to identify personality and situational variables that mediate students' attitude when confronted with a mathematics task. Students worked on a mathematics task in two subsequent sessions. Effects of perceived task outcome at the first session on students' attitude at the second session were investigated. In addition, we investigated how differences in task demands influenced students' attitude. Variations in task demands were provoked by different conditions in task-instruction. In one condition, students were told that the result on the test would add to their mark on mathematics. This outcome orienting condition was contrasted with a task-orienting condition where students were told that the results on the test would not be used to give individual grades. Participants were sixth grade students (N = 345; aged 11-12 years) from 14 primary schools. Multivariate and univariate analyses of (co)variance were applied to the data. Independent variables were goal orientation, task demands, and perceived task outcome, with task-specific variables (estimated competence for the task, task attraction, task relevance, and willingness to invest effort) as the dependent variables. The results showed that previous perceived task outcome had a substantial impact on students' attitude. Additional but smaller effects were found for variation in task demands. Furthermore, effects of previous perceived task outcome and task demands were related to goal orientation. The resulting pattern confirmed that, in general, performance-oriented learning goals emphasised the negative impact of failure experiences, whereas task-oriented learning goals had a strengthening effect on how success experiences influenced students' attitude.

Job task characteristics of Australian emergency services volunteers during search and rescue operations.

PubMed

Silk, Aaron; Lenton, Gavin; Savage, Robbie; Aisbett, Brad

2018-02-01

Search and rescue operations are necessary in locating, assisting and recovering individuals lost or in distress. In Australia, land-based search and rescue roles require a range of physically demanding tasks undertaken in dynamic and challenging environments. The aim of the current research was to identify and characterise the physically demanding tasks inherent to search and rescue operation personnel within Australia. These aims were met through a subjective job task analysis approach. In total, 11 criterion tasks were identified by personnel. These tasks were the most physically demanding, frequently occurring and operationally important tasks to these specialist roles. Muscular strength was the dominant fitness component for 7 of the 11 tasks. In addition to the discrete criterion tasks, an operational scenario was established. With the tasks and operational scenario identified, objective task analysis procedures can be undertaken so that practitioners can implement evidence-based strategies, such as physical selection procedures and task-based physical training programs, commensurate with the physical demands of search and rescue job roles. Practitioner Summary: The identification of physically demanding tasks amongst specialist emergency service roles predicates health and safety strategies which can be incorporated into organisations. Knowledge of physical task parameters allows employers to mitigate injury risk through the implementation of strategies modelled on the precise physical demands of the role.

Cognitive Demand of Model Tracing Tutor Tasks: Conceptualizing and Predicting How Deeply Students Engage

ERIC Educational Resources Information Center

Kessler, Aaron M.; Stein, Mary Kay; Schunn, Christian D.

2015-01-01

Model tracing tutors represent a technology designed to mimic key elements of one-on-one human tutoring. We examine the situations in which such supportive computer technologies may devolve into mindless student work with little conceptual understanding or student development. To analyze the support of student intellectual work in the model…

Incremental update of electrostatic interactions in adaptively restrained particle simulations.

PubMed

Edorh, Semeho Prince A; Redon, Stéphane

2018-04-06

The computation of long-range potentials is one of the demanding tasks in Molecular Dynamics. During the last decades, an inventive panoply of methods was developed to reduce the CPU time of this task. In this work, we propose a fast method dedicated to the computation of the electrostatic potential in adaptively restrained systems. We exploit the fact that, in such systems, only some particles are allowed to move at each timestep. We developed an incremental algorithm derived from a multigrid-based alternative to traditional Fourier-based methods. Our algorithm was implemented inside LAMMPS, a popular molecular dynamics simulation package. We evaluated the method on different systems. We showed that the new algorithm's computational complexity scales with the number of active particles in the simulated system, and is able to outperform the well-established Particle Particle Particle Mesh (P3M) for adaptively restrained simulations. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Quantifying Narrative Ability in Autism Spectrum Disorder: A Computational Linguistic Analysis of Narrative Coherence

PubMed Central

Losh, Molly; Gordon, Peter C.

2014-01-01

Autism Spectrum Disorder (ASD) is characterized by difficulties with social communication and functioning, and ritualistic/repetitive behaviors (American Psychiatric Association, 2013). While substantial heterogeneity exists in symptom expression, impairments in language discourse skills, including narrative, are universally observed (Tager-Flusberg, Paul, & Lord, 2005). This study applied a computational linguistic tool, Latent Semantic Analysis (LSA), to objectively characterize narrative performance in ASD across two narrative contexts differing in interpersonal and cognitive demands. Results indicated that individuals with ASD produced narratives comparable in semantic content to those from controls when narrating from a picture book, but produced narratives diminished in semantic quality in a more demanding narrative recall task. Results are discussed in terms of the utility of LSA as a quantitative, objective, and efficient measure of narrative ability. PMID:24915929

Attention Demands of Spoken Word Planning: A Review

PubMed Central

Roelofs, Ardi; Piai, Vitória

2011-01-01

Attention and language are among the most intensively researched abilities in the cognitive neurosciences, but the relation between these abilities has largely been neglected. There is increasing evidence, however, that linguistic processes, such as those underlying the planning of words, cannot proceed without paying some form of attention. Here, we review evidence that word planning requires some but not full attention. The evidence comes from chronometric studies of word planning in picture naming and word reading under divided attention conditions. It is generally assumed that the central attention demands of a process are indexed by the extent that the process delays the performance of a concurrent unrelated task. The studies measured the speed and accuracy of linguistic and non-linguistic responding as well as eye gaze durations reflecting the allocation of attention. First, empirical evidence indicates that in several task situations, processes up to and including phonological encoding in word planning delay, or are delayed by, the performance of concurrent unrelated non-linguistic tasks. These findings suggest that word planning requires central attention. Second, empirical evidence indicates that conflicts in word planning may be resolved while concurrently performing an unrelated non-linguistic task, making a task decision, or making a go/no-go decision. These findings suggest that word planning does not require full central attention. We outline a computationally implemented theory of attention and word planning, and describe at various points the outcomes of computer simulations that demonstrate the utility of the theory in accounting for the key findings. Finally, we indicate how attention deficits may contribute to impaired language performance, such as in individuals with specific language impairment. PMID:22069393

A review of GPU-based medical image reconstruction.

PubMed

Després, Philippe; Jia, Xun

2017-10-01

Tomographic image reconstruction is a computationally demanding task, even more so when advanced models are used to describe a more complete and accurate picture of the image formation process. Such advanced modeling and reconstruction algorithms can lead to better images, often with less dose, but at the price of long calculation times that are hardly compatible with clinical workflows. Fortunately, reconstruction tasks can often be executed advantageously on Graphics Processing Units (GPUs), which are exploited as massively parallel computational engines. This review paper focuses on recent developments made in GPU-based medical image reconstruction, from a CT, PET, SPECT, MRI and US perspective. Strategies and approaches to get the most out of GPUs in image reconstruction are presented as well as innovative applications arising from an increased computing capacity. The future of GPU-based image reconstruction is also envisioned, based on current trends in high-performance computing. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Two-and-a-half-year-olds succeed at a traditional false-belief task with reduced processing demands

PubMed Central

Scott, Rose M.; Baillargeon, Renée

2016-01-01

When tested with traditional false-belief tasks, which require answering a standard question about the likely behavior of an agent with a false belief, children perform below chance until age 4 y or later. When tested without such questions, however, children give evidence of false-belief understanding much earlier. Are traditional tasks difficult because they tap a more advanced form of false-belief understanding (fundamental-change view) or because they impose greater processing demands (processing-demands view)? Evidence that young children succeed at traditional false-belief tasks when processing demands are reduced would support the latter view. In prior research, reductions in inhibitory-control demands led to improvements in young children’s performance, but often only to chance (instead of below-chance) levels. Here we examined whether further reductions in processing demands might lead to success. We speculated that: (i) young children could respond randomly in a traditional low-inhibition task because their limited information-processing resources are overwhelmed by the total concurrent processing demands in the task; and (ii) these demands include those from the response-generation process activated by the standard question. This analysis suggested that 2.5-y-old toddlers might succeed at a traditional low-inhibition task if response-generation demands were also reduced via practice trials. As predicted, toddlers performed above chance following two response-generation practice trials; toddlers failed when these trials either were rendered less effective or were used in a high-inhibition task. These results support the processing-demands view: Even toddlers succeed at a traditional false-belief task when overall processing demands are reduced. PMID:27821728

ExM:System Support for Extreme-Scale, Many-Task Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, Daniel S

The ever-increasing power of supercomputer systems is both driving and enabling the emergence of new problem-solving methods that require the effi cient execution of many concurrent and interacting tasks. Methodologies such as rational design (e.g., in materials science), uncertainty quanti fication (e.g., in engineering), parameter estimation (e.g., for chemical and nuclear potential functions, and in economic energy systems modeling), massive dynamic graph pruning (e.g., in phylogenetic searches), Monte-Carlo- based iterative fi xing (e.g., in protein structure prediction), and inverse modeling (e.g., in reservoir simulation) all have these requirements. These many-task applications frequently have aggregate computing needs that demand the fastestmore » computers. For example, proposed next-generation climate model ensemble studies will involve 1,000 or more runs, each requiring 10,000 cores for a week, to characterize model sensitivity to initial condition and parameter uncertainty. The goal of the ExM project is to achieve the technical advances required to execute such many-task applications efficiently, reliably, and easily on petascale and exascale computers. In this way, we will open up extreme-scale computing to new problem solving methods and application classes. In this document, we report on combined technical progress of the collaborative ExM project, and the institutional financial status of the portion of the project at University of Chicago, over the rst 8 months (through April 30, 2011)« less

Two Trackers Are Better than One: Information about the Co-actor's Actions and Performance Scores Contribute to the Collective Benefit in a Joint Visuospatial Task.

PubMed

Wahn, Basil; Kingstone, Alan; König, Peter

2017-01-01

When humans collaborate, they often distribute task demands in order to reach a higher performance compared to performing the same task alone (i.e., a collective benefit). Here, we tested to what extent receiving information about the actions of a co-actor, performance scores, or receiving both types of information impacts the collective benefit in a collaborative multiple object tracking task. In a between-subject design, pairs of individuals jointly tracked a subset of target objects among several moving distractor objects on a computer screen for a 100 trials. At the end of a trial, pairs received performance scores (Experiment 1), information about their partner's target selections (Experiment 2), or both types of information (Experiment 3). In all experiments, the performance of the pair exceeded the individual performances and the simulated performance of two independent individuals combined. Initially, when receiving both types of information (Experiment 3), pairs achieved the highest performance and divided task demands most efficiently compared to the other two experiments. Over time, performances and the ability to divide task demands for pairs receiving a single type of information converged with those receiving both, suggesting that pairs' coordination strategies become equally effective over time across experiments. However, pairs' performances never reached a theoretical limit of performance in all experiments. For distributing task demands, members of a pair predominantly used a left-right division of labor strategy (i.e., the leftmost targets were tracked by one co-actor while the rightmost targets were tracked by the other co-actor). Overall, findings of the present study suggest that receiving information about actions of a co-actor, performance scores, or receiving both enables pairs to devise effective division of labor strategies in a collaborative visuospatial task. However, when pairs had both types of information available, the formation of division of labor strategies was facilitated, indicating that pairs benefited the most from having both types of information available (i.e., actions about the co-actor and performance scores). Findings are applicable to circumstances in which humans need to perform collaborative visuospatial tasks that are time-critical and/or only allow a very limited exchange of information between co-actors.

Cognitive task demands, self-control demands and the mental well-being of office workers.

PubMed

Bridger, Robert S; Brasher, Kate

2011-09-01

The cognitive task demands of office workers and the self-control demands of their work roles were measured in a sample of 196 employees in two different office layouts using a self-report questionnaire, which was circulated electronically. Multiple linear regression analysis revealed that both factors were associated with mental well-being, but not with physical well-being, while controlling for exposure to psychosocial stressors. The interaction between cognitive task demands and self-control demands had the strongest association with mental well-being, suggesting that the deleterious effect of one was greater when the other was present. An exploratory analysis revealed that the association was stronger for employees working in a large open-plan office than for those working in smaller offices with more privacy. Frustration of work goals was the cognitive task demand having the strongest negative impact on mental well-being. Methodological limitations and scale psychometrics (particularly the use of the NASA Task Load Index) are discussed. STATEMENT OF RELEVANCE: Modern office work has high mental demands and low physical demands and there is a need to design offices to prevent adverse psychological reactions. It is shown that cognitive task demands interact with self-control demands to degrade mental well-being. The association was stronger in an open-plan office.

Visual processing speed.

PubMed

Owsley, Cynthia

2013-09-20

Older adults commonly report difficulties in visual tasks of everyday living that involve visual clutter, secondary task demands, and time sensitive responses. These difficulties often cannot be attributed to visual sensory impairment. Techniques for measuring visual processing speed under divided attention conditions and among visual distractors have been developed and have established construct validity in that those older adults performing poorly in these tests are more likely to exhibit daily visual task performance problems. Research suggests that computer-based training exercises can increase visual processing speed in older adults and that these gains transfer to enhancement of health and functioning and a slowing in functional and health decline as people grow older. Copyright © 2012 Elsevier Ltd. All rights reserved.

History-Based Response Threshold Model for Division of Labor in Multi-Agent Systems

PubMed Central

Lee, Wonki; Kim, DaeEun

2017-01-01

Dynamic task allocation is a necessity in a group of robots. Each member should decide its own task such that it is most commensurate with its current state in the overall system. In this work, the response threshold model is applied to a dynamic foraging task. Each robot employs a task switching function based on the local task demand obtained from the surrounding environment, and no communication occurs between the robots. Each individual member has a constant-sized task demand history that reflects the global demand. In addition, it has response threshold values for all of the tasks and manages the task switching process depending on the stimuli of the task demands. The robot then determines the task to be executed to regulate the overall division of labor. This task selection induces a specialized tendency for performing a specific task and regulates the division of labor. In particular, maintaining a history of the task demands is very effective for the dynamic foraging task. Various experiments are performed using a simulation with multiple robots, and the results show that the proposed algorithm is more effective as compared to the conventional model. PMID:28555031

Talking while walking: Cognitive loading and injurious falls in Parkinson's disease.

PubMed

LaPointe, Leonard L; Stierwalt, Julie A G; Maitland, Charles G

2010-10-01

Multitasking has become a way of life, from operating multiple software packages simultaneously on a computer, to carrying on a conversation on a cell phone while driving. Perhaps one of the most common dual tasks performed is talking while walking. In isolation, neither task would be considered difficult to perform, yet when coupled, the relative ease of each task may change. This paper details significant problems that result from injurious falls, and points out the vulnerability of those who have been diagnosed with Parkinson's disease. In addition, it provides an illustrative study that demonstrates the potential danger of talking while walking, especially when the cognitive-linguistic complexity of verbal tasks is manipulated. In this investigation, 25 participants with Parkinson's disease and 13 participants without neurological compromise completed gait tasks while conducting tasks of low (counting by ones), middle (serial subtraction of threes), and high load (alpha-numeric sequencing). The results indicated that cognitive-linguistic demand had an impact on gait, the effects of which were demonstrated in individuals without neurological compromise as well as those with Parkinson's disease. One finding, altered double-support time, distinguished the Parkinson group from the control participants. These results suggest that it might be prudent for healthcare professionals and caregivers to alter expectations and monitor the cognitive-linguistic demands placed on elderly individuals, particularly those with neurological compromise who might be at greater risk for injurious falls.

Avoiding the conflict: Metacognitive awareness drives the selection of low-demand contexts.

PubMed

Desender, Kobe; Buc Calderon, Cristian; Van Opstal, Filip; Van den Bussche, Eva

2017-07-01

Previous research attempted to explain how humans strategically adapt behavior in order to achieve successful task performance. Recently, it has been suggested that 1 potential strategy is to avoid tasks that are too demanding. Here, we report 3 experiments that investigate the empirically neglected role of metacognitive awareness in this process. In these experiments, participants could freely choose between performing a task in either a high-demand or a low-demand context. Using subliminal priming, we ensured that participants were not aware of the visual stimuli creating these different demand contexts. Our results showed that participants who noticed a difference in task difficulty (i.e., metacognitive aware participants) developed a clear preference for the low-demand context. In contrast, participants who experienced no difference in task difficulty (i.e., metacognitive unaware participants) based their choices on variables unrelated to cognitive demand (e.g., the color or location associated with a context), and did not develop a preference for the low-demand context. Crucially, this pattern was found despite identical task performance in both metacognitive awareness groups. A multiple regression approach confirmed that metacognitive awareness was the main factor driving the preference for low-demand contexts. These results argue for an important role of metacognitive awareness in the strategic avoidance of demanding tasks. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation

PubMed Central

Forsman, Mikael; Richter, Hans O.

2017-01-01

Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions), and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks), astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work. PMID:28832612

Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation.

PubMed

Zetterberg, Camilla; Forsman, Mikael; Richter, Hans O

2017-01-01

Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions), and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks), astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work.

Dissociating response conflict and error likelihood in anterior cingulate cortex.

PubMed

Yeung, Nick; Nieuwenhuis, Sander

2009-11-18

Neuroimaging studies consistently report activity in anterior cingulate cortex (ACC) in conditions of high cognitive demand, leading to the view that ACC plays a crucial role in the control of cognitive processes. According to one prominent theory, the sensitivity of ACC to task difficulty reflects its role in monitoring for the occurrence of competition, or "conflict," between responses to signal the need for increased cognitive control. However, a contrasting theory proposes that ACC is the recipient rather than source of monitoring signals, and that ACC activity observed in relation to task demand reflects the role of this region in learning about the likelihood of errors. Response conflict and error likelihood are typically confounded, making the theories difficult to distinguish empirically. The present research therefore used detailed computational simulations to derive contrasting predictions regarding ACC activity and error rate as a function of response speed. The simulations demonstrated a clear dissociation between conflict and error likelihood: fast response trials are associated with low conflict but high error likelihood, whereas slow response trials show the opposite pattern. Using the N2 component as an index of ACC activity, an EEG study demonstrated that when conflict and error likelihood are dissociated in this way, ACC activity tracks conflict and is negatively correlated with error likelihood. These findings support the conflict-monitoring theory and suggest that, in speeded decision tasks, ACC activity reflects current task demands rather than the retrospective coding of past performance.

The normalities and abnormalities associated with speech in psychometrically-defined schizotypy.

PubMed

Cohen, Alex S; Auster, Tracey L; McGovern, Jessica E; MacAulay, Rebecca K

2014-12-01

Speech deficits are thought to be an important feature of schizotypy--defined as the personality organization reflecting a putative liability for schizophrenia. There is reason to suspect that these deficits manifest as a function of limited cognitive resources. To evaluate this idea, we examined speech from individuals with psychometrically-defined schizotypy during a low cognitively-demanding task versus a relatively high cognitively-demanding task. A range of objective, computer-based measures of speech tapping speech production (silence, number and length of pauses, number and length of utterances), speech variability (global and local intonation and emphasis) and speech content (word fillers, idea density) were employed. Data for control (n=37) and schizotypy (n=39) groups were examined. Results did not confirm our hypotheses. While the cognitive-load task reduced speech expressivity for subjects as a group for most variables, the schizotypy group was not more pathological in speech characteristics compared to the control group. Interestingly, some aspects of speech in schizotypal versus control subjects were healthier under high cognitive load. Moreover, schizotypal subjects performed better, at a trend level, than controls on the cognitively demanding task. These findings hold important implications for our understanding of the neurocognitive architecture associated with the schizophrenia-spectrum. Of particular note concerns the apparent mismatch between self-reported schizotypal traits and objective performance, and the resiliency of speech under cognitive stress in persons with high levels of schizotypy. Copyright © 2014 Elsevier B.V. All rights reserved.

Transferring control demands across incidental learning tasks – stronger sequence usage in serial reaction task after shortcut option in letter string checking

PubMed Central

Gaschler, Robert; Marewski, Julian N.; Wenke, Dorit; Frensch, Peter A.

2014-01-01

After incidentally learning about a hidden regularity, participants can either continue to solve the task as instructed or, alternatively, apply a shortcut. Past research suggests that the amount of conflict implied by adopting a shortcut seems to bias the decision for vs. against continuing instruction-coherent task processing. We explored whether this decision might transfer from one incidental learning task to the next. Theories that conceptualize strategy change in incidental learning as a learning-plus-decision phenomenon suggest that high demands to adhere to instruction-coherent task processing in Task 1 will impede shortcut usage in Task 2, whereas low control demands will foster it. We sequentially applied two established incidental learning tasks differing in stimuli, responses and hidden regularity (the alphabet verification task followed by the serial reaction task, SRT). While some participants experienced a complete redundancy in the task material of the alphabet verification task (low demands to adhere to instructions), for others the redundancy was only partial. Thus, shortcut application would have led to errors (high demands to follow instructions). The low control demand condition showed the strongest usage of the fixed and repeating sequence of responses in the SRT. The transfer results are in line with the learning-plus-decision view of strategy change in incidental learning, rather than with resource theories of self-control. PMID:25506336

Functional connectivity of task context representations in prefrontal nodes of the multiple demand network.

PubMed

Stiers, Peter; Goulas, Alexandros

2018-06-01

A subset of regions in the lateral and medial prefrontal cortex and the anterior insula increase their activity level whenever a cognitive task becomes more demanding, regardless of the specific nature of this demand. During execution of a task, these areas and the surrounding cortex temporally encode aspects of the task context in spatially distributed patterns of activity. It is not clear whether these patterns reflect underlying anatomical subnetworks that still exist when task execution has finished. We use fMRI in 12 participants performing alternating blocks of three cognitive tasks to address this question. A first data set is used to define multiple demand regions in each participant. A second dataset from the same participants is used to determine multiple demand voxel assemblies with a preference for one task over the others. We then show that these voxels remain functionally coupled during execution of non-preferred tasks and that they exhibit stronger functional connectivity during rest. This indicates that the assemblies of task preference sharing voxels reflect patterns of underlying anatomical connections. Moreover, we show that voxels preferring the same task have more similar whole brain functional connectivity profiles that are consistent across participants. This suggests that voxel assemblies differ in patterns of input-output connections, most likely reflecting task demand-specific information exchange.

Ergonomic intervention for employed persons with rheumatic conditions.

PubMed

Allaire, Saralynn J; Backman, Catherine L; Alheresh, Rawan; Baker, Nancy A

2013-01-01

Prior articles in this series on employment and arthritis have documented the major impact arthritis and other rheumatic conditions have on employment. As expected, physically demanding job tasks, including hand use, are substantial risk factors for work limitation. Computer use has been increasing. People with arthritis may choose occupations involving extensive computer use to avoid occupations with other physical demands. But studies show many people with arthritis conditions have difficulty using computers.Ergonomic assessment and implementation helps relieve the physical and other demands of jobs. The Ergonomic Assessment Tool for Arthritis (EATA) is specifically for people with arthritis conditions. Since the EATA can be conducted off worksite, it is feasible to use with workers not wishing to disclose their condition to their employer. Available research supports the effectiveness of ergonomic intervention as a viable method to reduce work limitation for persons with arthritis. Some workers will need additional vocational intervention to remain employed long term. However, ergonomic intervention is a useful first step, as it promotes awareness of arthritis effects on work activities. Assisting workers with arthritis or other rheumatic conditions to use ergonomics to enhance their ability to work well should be an important aspect of managing these conditions.

Mental workload and cognitive task automaticity: an evaluation of subjective and time estimation metrics.

PubMed

Liu, Y; Wickens, C D

1994-11-01

The evaluation of mental workload is becoming increasingly important in system design and analysis. The present study examined the structure and assessment of mental workload in performing decision and monitoring tasks by focusing on two mental workload measurements: subjective assessment and time estimation. The task required the assignment of a series of incoming customers to the shortest of three parallel service lines displayed on a computer monitor. The subject was either in charge of the customer assignment (manual mode) or was monitoring an automated system performing the same task (automatic mode). In both cases, the subjects were required to detect the non-optimal assignments that they or the computer had made. Time pressure was manipulated by the experimenter to create fast and slow conditions. The results revealed a multi-dimensional structure of mental workload and a multi-step process of subjective workload assessment. The results also indicated that subjective workload was more influenced by the subject's participatory mode than by the factor of task speed. The time estimation intervals produced while performing the decision and monitoring tasks had significantly greater length and larger variability than those produced while either performing no other tasks or performing a well practised customer assignment task. This result seemed to indicate that time estimation was sensitive to the presence of perceptual/cognitive demands, but not to response related activities to which behavioural automaticity has developed.

Alpha Control - A new Concept in SPM Control

NASA Astrophysics Data System (ADS)

Spizig, P.; Sanchen, D.; Volswinkler, G.; Ibach, W.; Koenen, J.

2006-03-01

Controlling modern Scanning Probe Microscopes demands highly sophisticated electronics. While flexibility and powerful computing power is of great importance in facilitating the variety of measurement modes, extremely low noise is also a necessity. Accordingly, modern SPM Controller designs are based on digital electronics to overcome the drawbacks of analog designs. While todays SPM controllers are based on DSPs or Microprocessors and often still incorporate analog parts, we are now introducing a completely new approach: Using a Field Programmable Gate Array (FPGA) to implement the digital control tasks allows unrivalled data processing speed by computing all tasks in parallel within a single chip. Time consuming task switching between data acquisition, digital filtering, scanning and the computing of feedback signals can be completely avoided. Together with a star topology to avoid any bus limitations in accessing the variety of ADCs and DACs, this design guarantees for the first time an entirely deterministic timing capability in the nanosecond regime for all tasks. This becomes especially useful for any external experiments which must be synchronized with the scan or for high speed scans that require not only closed loop control of the scanner, but also dynamic correction of the scan movement. Delicate samples additionally benefit from extremely high sample rates, allowing highly resolved signals and low noise levels.

Skills-demands compatibility as a determinant of flow experience in an inductive reasoning task.

PubMed

Schiefele, Ulrich; Raabe, Andreas

2011-10-01

The skills-demands fit hypothesis of flow theory was examined. Based on the earlier finding that high demands in a game situation do not reduce the experience of flow, a cognitive task paradigm was used. The effect of skills-demands compatibility on the experience of flow but not of other, similar psychological states (i.e., concentration, negative and positive activation) was also investigated. Participants were 89 undergraduate students who worked on a number of inductive reasoning tasks in four successive trials with or without skills-demands compatibility. The results clearly supported the skills-demands fit hypothesis; concentration and activation were affected only by the tasks' difficulty. Inductive reasoning tasks are a useful tool for the experimental analysis of flow, and skills-demands compatibility is a significant and powerful condition of flow, but not of other, similar psychological states.

Interactive Light Stimulus Generation with High Performance Real-Time Image Processing and Simple Scripting

PubMed Central

Szécsi, László; Kacsó, Ágota; Zeck, Günther; Hantz, Péter

2017-01-01

Light stimulation with precise and complex spatial and temporal modulation is demanded by a series of research fields like visual neuroscience, optogenetics, ophthalmology, and visual psychophysics. We developed a user-friendly and flexible stimulus generating framework (GEARS GPU-based Eye And Retina Stimulation Software), which offers access to GPU computing power, and allows interactive modification of stimulus parameters during experiments. Furthermore, it has built-in support for driving external equipment, as well as for synchronization tasks, via USB ports. The use of GEARS does not require elaborate programming skills. The necessary scripting is visually aided by an intuitive interface, while the details of the underlying software and hardware components remain hidden. Internally, the software is a C++/Python hybrid using OpenGL graphics. Computations are performed on the GPU, and are defined in the GLSL shading language. However, all GPU settings, including the GPU shader programs, are automatically generated by GEARS. This is configured through a method encountered in game programming, which allows high flexibility: stimuli are straightforwardly composed using a broad library of basic components. Stimulus rendering is implemented solely in C++, therefore intermediary libraries for interfacing could be omitted. This enables the program to perform computationally demanding tasks like en-masse random number generation or real-time image processing by local and global operations. PMID:29326579

Seeing tones and hearing rectangles - Attending to simultaneous auditory and visual events

NASA Technical Reports Server (NTRS)

Casper, Patricia A.; Kantowitz, Barry H.

1985-01-01

The allocation of attention in dual-task situations depends on both the overall and the momentary demands associated with both tasks. Subjects in an inclusive- or reaction-time task responded to changes in simultaneous sequences of discrete auditory and visual stimuli. Performance on individual trials was affected by (1) the ratio of stimuli in the two tasks, (2) response demands of the two tasks, and (3) patterns inherent in the demands of one task.

Hysteresis in Mental Workload and Task Performance: The Influence of Demand Transitions and Task Prioritization.

PubMed

Jansen, Reinier J; Sawyer, Ben D; van Egmond, René; de Ridder, Huib; Hancock, Peter A

2016-12-01

We examine how transitions in task demand are manifested in mental workload and performance in a dual-task setting. Hysteresis has been defined as the ongoing influence of demand levels prior to a demand transition. Authors of previous studies predominantly examined hysteretic effects in terms of performance. However, little is known about the temporal development of hysteresis in mental workload. A simulated driving task was combined with an auditory memory task. Participants were instructed to prioritize driving or to prioritize both tasks equally. Three experimental conditions with low, high, and low task demands were constructed by manipulating the frequency of lane changing. Multiple measures of subjective mental workload were taken during experimental conditions. Contrary to our prediction, no hysteretic effects were found after the high- to low-demand transition. However, a hysteretic effect in mental workload was found within the high-demand condition, which degraded toward the end of the high condition. Priority instructions were not reflected in performance. Online assessment of both performance and mental workload demonstrates the transient nature of hysteretic effects. An explanation for the observed hysteretic effect in mental workload is offered in terms of effort regulation. An informed arrival at the scene is important in safety operations, but peaks in mental workload should be avoided to prevent buildup of fatigue. Therefore, communication technologies should incorporate the historical profile of task demand. © 2016, Human Factors and Ergonomics Society.

A Demands-Resources Model of Work Pressure in IT Student Task Groups

ERIC Educational Resources Information Center

Wilson, E. Vance; Sheetz, Steven D.

2010-01-01

This paper presents an initial test of the group task demands-resources (GTD-R) model of group task performance among IT students. We theorize that demands and resources in group work influence formation of perceived group work pressure (GWP) and that heightened levels of GWP inhibit group task performance. A prior study identified 11 factors…

Bottom-up and top-down computations in word- and face-selective cortex

PubMed Central

Kay, Kendrick N; Yeatman, Jason D

2017-01-01

The ability to read a page of text or recognize a person's face depends on category-selective visual regions in ventral temporal cortex (VTC). To understand how these regions mediate word and face recognition, it is necessary to characterize how stimuli are represented and how this representation is used in the execution of a cognitive task. Here, we show that the response of a category-selective region in VTC can be computed as the degree to which the low-level properties of the stimulus match a category template. Moreover, we show that during execution of a task, the bottom-up representation is scaled by the intraparietal sulcus (IPS), and that the level of IPS engagement reflects the cognitive demands of the task. These results provide an account of neural processing in VTC in the form of a model that addresses both bottom-up and top-down effects and quantitatively predicts VTC responses. DOI: http://dx.doi.org/10.7554/eLife.22341.001 PMID:28226243

Age-Related Changes in Dynamic Postural Control and Attentional Demands are Minimally Affected by Local Muscle Fatigue

PubMed Central

Remaud, Anthony; Thuong-Cong, Cécile; Bilodeau, Martin

2016-01-01

Normal aging results in alterations in the visual, vestibular and somtaosensory systems, which in turn modify the control of balance. Muscle fatigue may exacerbate these age-related changes in sensory and motor functions, and also increase the attentional demands associated with dynamic postural control. The purpose of this study was to investigate the effect of aging on dynamic postural control and posture-related attentional demands before and after a plantar flexor fatigue protocol. Participants (young adults: n = 15; healthy seniors: n = 13) performed a dynamic postural task along the antero-posterior (AP) and the medio-lateral (ML) axes, with and without the addition of a simple reaction time (RT) task. The dynamic postural task consisted in following a moving circle on a computer screen with the representation of the center of pressure (COP). This protocol was repeated before and after a fatigue task where ankle plantar flexor muscles were targeted. The mean COP-target distance and the mean COP velocity were calculated for each trial. Cross-correlation analyses between the COP and target displacements were also performed. RTs were recorded during dual-task trials. Results showed that while young adults adopted an anticipatory control mode to move their COP as close as possible to the target center, seniors adopted a reactive control mode, lagging behind the target center. This resulted in longer COP-target distance and higher COP velocity in the latter group. Concurrently, RT increased more in seniors when switching from static stance to dynamic postural conditions, suggesting potential alterations in the central nervous system (CNS) functions. Finally, plantar flexor muscle fatigue and dual-tasking had only minor effects on dynamic postural control of both young adults and seniors. Future studies should investigate why the fatigue-induced changes in quiet standing postural control do not seem to transfer to dynamic balance tasks. PMID:26834626

Video-task assessment of learning and memory in Macaques (Macaca mulatta) - Effects of stimulus movement on performance

NASA Technical Reports Server (NTRS)

Washburn, David A.; Hopkins, William D.; Rumbaugh, Duane M.

1989-01-01

Effects of stimulus movement on learning, transfer, matching, and short-term memory performance were assessed with 2 monkeys using a video-task paradigm in which the animals responded to computer-generated images by manipulating a joystick. Performance on tests of learning set, transfer index, matching to sample, and delayed matching to sample in the video-task paradigm was comparable to that obtained in previous investigations using the Wisconsin General Testing Apparatus. Additionally, learning, transfer, and matching were reliably and significantly better when the stimuli or discriminanda moved than when the stimuli were stationary. External manipulations such as stimulus movement may increase attention to the demands of a task, which in turn should increase the efficiency of learning. These findings have implications for the investigation of learning in other populations, as well as for the application of the video-task paradigm to comparative study.

Mobile-Cloud Assisted Video Summarization Framework for Efficient Management of Remote Sensing Data Generated by Wireless Capsule Sensors

PubMed Central

Mehmood, Irfan; Sajjad, Muhammad; Baik, Sung Wook

2014-01-01

Wireless capsule endoscopy (WCE) has great advantages over traditional endoscopy because it is portable and easy to use, especially in remote monitoring health-services. However, during the WCE process, the large amount of captured video data demands a significant deal of computation to analyze and retrieve informative video frames. In order to facilitate efficient WCE data collection and browsing task, we present a resource- and bandwidth-aware WCE video summarization framework that extracts the representative keyframes of the WCE video contents by removing redundant and non-informative frames. For redundancy elimination, we use Jeffrey-divergence between color histograms and inter-frame Boolean series-based correlation of color channels. To remove non-informative frames, multi-fractal texture features are extracted to assist the classification using an ensemble-based classifier. Owing to the limited WCE resources, it is impossible for the WCE system to perform computationally intensive video summarization tasks. To resolve computational challenges, mobile-cloud architecture is incorporated, which provides resizable computing capacities by adaptively offloading video summarization tasks between the client and the cloud server. The qualitative and quantitative results are encouraging and show that the proposed framework saves information transmission cost and bandwidth, as well as the valuable time of data analysts in browsing remote sensing data. PMID:25225874

Mobile-cloud assisted video summarization framework for efficient management of remote sensing data generated by wireless capsule sensors.

PubMed

Mehmood, Irfan; Sajjad, Muhammad; Baik, Sung Wook

2014-09-15

Wireless capsule endoscopy (WCE) has great advantages over traditional endoscopy because it is portable and easy to use, especially in remote monitoring health-services. However, during the WCE process, the large amount of captured video data demands a significant deal of computation to analyze and retrieve informative video frames. In order to facilitate efficient WCE data collection and browsing task, we present a resource- and bandwidth-aware WCE video summarization framework that extracts the representative keyframes of the WCE video contents by removing redundant and non-informative frames. For redundancy elimination, we use Jeffrey-divergence between color histograms and inter-frame Boolean series-based correlation of color channels. To remove non-informative frames, multi-fractal texture features are extracted to assist the classification using an ensemble-based classifier. Owing to the limited WCE resources, it is impossible for the WCE system to perform computationally intensive video summarization tasks. To resolve computational challenges, mobile-cloud architecture is incorporated, which provides resizable computing capacities by adaptively offloading video summarization tasks between the client and the cloud server. The qualitative and quantitative results are encouraging and show that the proposed framework saves information transmission cost and bandwidth, as well as the valuable time of data analysts in browsing remote sensing data.

Driving monotonous routes in a train simulator: the effect of task demand on driving performance and subjective experience.

PubMed

Dunn, Naomi; Williamson, Ann

2012-01-01

Although monotony is widely recognised as being detrimental to performance, its occurrence and effects are not yet well understood. This is despite the fact that task-related characteristics, such as monotony and low task demand, have been shown to contribute to performance decrements over time. Participants completed one of two simulated train-driving scenarios. Both were highly monotonous and differed only in terms of the level of cognitive demand required (i.e. low demand or high demand). These results highlight the seriously detrimental effects of the combination of monotony and low task demands and clearly show that even a relatively minor increase in cognitive demand can mitigate adverse monotony-related effects on performance for extended periods of time. Monotony is an inherent characteristic of transport industries, including rail, aviation and road transport, which can have adverse impact on safety, reliability and efficiency. This study highlights possible strategies for mitigating these adverse effects. Practitioner Summary: This study provides evidence for the importance of cognitive demand in mitigating monotony-related effects on performance. The results have clear implications for the rapid onset of performance deterioration in low demand monotonous tasks and demonstrate that these detrimental performance effects can be overcome with simple solutions, such as making the task more cognitively engaging.

Collaborative activity between parietal and dorso-lateral prefrontal cortex in dynamic spatial working memory revealed by fMRI.

PubMed

Diwadkar, V A; Carpenter, P A; Just, M A

2000-07-01

Functional MRI was used to determine how the constituents of the cortical network subserving dynamic spatial working memory respond to two types of increases in task complexity. Participants mentally maintained the most recent location of either one or three objects as the three objects moved discretely in either a two- or three-dimensional array. Cortical activation in the dorsolateral prefrontal (DLPFC) and the parietal cortex increased as a function of the number of object locations to be maintained and the dimensionality of the display. An analysis of the response characteristics of the individual voxels showed that a large proportion were activated only when both the variables imposed the higher level of demand. A smaller proportion were activated specifically in response to increases in task demand associated with each of the independent variables. A second experiment revealed the same effect of dimensionality in the parietal cortex when the movement of objects was signaled auditorily rather than visually, indicating that the additional representational demands induced by 3-D space are independent of input modality. The comodulation of activation in the prefrontal and parietal areas by the amount of computational demand suggests that the collaboration between areas is a basic feature underlying much of the functionality of spatial working memory. Copyright 2000 Academic Press.

Controlling the stream of thought: working memory capacity predicts adjustment of mind-wandering to situational demands.

PubMed

Rummel, Jan; Boywitt, C Dennis

2014-10-01

Although engaging in task-unrelated thoughts can be enjoyable and functional under certain circumstances, allowing one's mind to wander off-task will come at a cost to performance in many situations. Given that task-unrelated thoughts need to be blocked out when the current task requires full attention, it has been argued that cognitive control is necessary to prevent mind-wandering from becoming maladaptive. Extending this idea, we exposed participants to tasks of different demands and assessed mind-wandering via thought probes. Employing a latent-change model, we found mind-wandering to be adjusted to current task demands. As hypothesized, the degree of adjustment was predicted by working memory capacity, indicating that participants with higher working memory capacity were more flexible in their coordination of on- and off-task thoughts. Notably, the better the adjustment, the smaller performance decrements due to increased task demands were. On the basis of these findings, we argue that cognitive control does not simply allow blocking out task-unrelated thoughts but, rather, allows one to flexibly adjust mind-wandering to situational demands.

Learner-Learner Interaction during Collaborative Pragmatic Tasks: The Role of Cognitive and Pragmatic Task Demands

ERIC Educational Resources Information Center

Kim, YouJin; Taguchi, Naoko

2016-01-01

Previous task complexity studies have suggested that learners produce more negotiation of meaning opportunities during complex tasks than simple tasks (Robinson, 2011). The present study builds on the existing task complexity literature by examining the impact of task complexity and pragmatic situational demands on the number of learning…

Neural Mechanisms for Adaptive Learned Avoidance of Mental Effort.

PubMed

Mitsuto Nagase, Asako; Onoda, Keiichi; Clifford Foo, Jerome; Haji, Tomoki; Akaishi, Rei; Yamaguchi, Shuhei; Sakai, Katsuyuki; Morita, Kenji

2018-02-05

Humans tend to avoid mental effort. Previous studies have demonstrated this tendency using various demand-selection tasks; participants generally avoid options associated with higher cognitive demand. However, it remains unclear whether humans avoid mental effort adaptively in uncertain and non-stationary environments, and if so, what neural mechanisms underlie this learned avoidance and whether they remain the same irrespective of cognitive-demand types. We addressed these issues by developing novel demand-selection tasks where associations between choice options and cognitive-demand levels change over time, with two variations using mental arithmetic and spatial reasoning problems (29:4 and 18:2 males:females). Most participants showed avoidance, and their choices depended on the demand experienced on multiple preceding trials. We assumed that participants updated the expected cost of mental effort through experience, and fitted their choices by reinforcement learning models, comparing several possibilities. Model-based fMRI analyses revealed that activity in the dorsomedial and lateral frontal cortices was positively correlated with the trial-by-trial expected cost for the chosen option commonly across the different types of cognitive demand, and also revealed a trend of negative correlation in the ventromedial prefrontal cortex. We further identified correlates of cost-prediction-error at time of problem-presentation or answering the problem, the latter of which partially overlapped with or were proximal to the correlates of expected cost at time of choice-cue in the dorsomedial frontal cortex. These results suggest that humans adaptively learn to avoid mental effort, having neural mechanisms to represent expected cost and cost-prediction-error, and the same mechanisms operate for various types of cognitive demand. SIGNIFICANCE STATEMENT In daily life, humans encounter various cognitive demands, and tend to avoid high-demand options. However, it remains unclear whether humans avoid mental effort adaptively under dynamically changing environments, and if so, what are the underlying neural mechanisms and whether they operate irrespective of cognitive-demand types. To address these issues, we developed novel tasks, where participants could learn to avoid high-demand options under uncertain and non-stationary environments. Through model-based fMRI analyses, we found regions whose activity was correlated with the expected mental effort cost, or cost-prediction-error, regardless of demand-type, with overlap or adjacence in the dorsomedial frontal cortex. This finding contributes to clarifying the mechanisms for cognitive-demand avoidance, and provides empirical building blocks for the emerging computational theory of mental effort. Copyright © 2018 the authors.

Modality dependence and intermodal transfer in the Corsi Spatial Sequence Task: Screen vs. Floor.

PubMed

Röser, Andrea; Hardiess, Gregor; Mallot, Hanspeter A

2016-07-01

Four versions of the Corsi Spatial Sequence Task (CSST) were tested in a complete within-subject design, investigating whether participants' performance depends on the modality of task presentation and reproduction that put different demands on spatial processing. Presentation of the sequence (encoding phase) and the reproduction (recall phase) were each carried out either on a computer screen or on the floor of a room, involving actual walking in the recall phase. Combinations of the two different encoding and recall procedures result in the modality conditions Screen-Screen, Screen-Floor, Floor-Screen, and Floor-Floor. Results show the expected decrease in performance with increasing sequence length, which is likely due to processing limitations of working memory. We also found differences in performance between the modality conditions indicating different involvements of spatial working memory processes. Participants performed best in the Screen-Screen modality condition. Floor-Screen and Floor-Floor modality conditions require additional working memory resources for reference frame transformation and spatial updating, respectively; the resulting impairment of the performance was about the same in these two conditions. Finally, the Screen-Floor modality condition requires both types of additional spatial demands and led to the poorest performance. Therefore, we suggest that besides the well-known spatial requirements of CSST, additional working memory resources are demanded in walking CSST supporting processes such as spatial updating, mental rotation, reference frame transformation, and the control of walking itself.

Effect of task load and task load increment on performance and workload

NASA Technical Reports Server (NTRS)

Hancock, P. A.; Williams, G.

1993-01-01

The goal of adaptive automated task allocation is the 'seamless' transfer of work demand between human and machine. Clearly, at the present time, we are far from this objective. One of the barriers to achieving effortless human-machine symbiosis is an inadequate understanding of the way in which operators themselves seek to reallocate demand among their own personal 'resources.' The paper addresses this through an examination of workload response, which scales an individual's reaction to common levels of experienced external demand. The results indicate the primary driver of performance is the absolute level of task demand over the increment in that demand.

High-Performance Data Analysis Tools for Sun-Earth Connection Missions

NASA Technical Reports Server (NTRS)

Messmer, Peter

2011-01-01

The data analysis tool of choice for many Sun-Earth Connection missions is the Interactive Data Language (IDL) by ITT VIS. The increasing amount of data produced by these missions and the increasing complexity of image processing algorithms requires access to higher computing power. Parallel computing is a cost-effective way to increase the speed of computation, but algorithms oftentimes have to be modified to take advantage of parallel systems. Enhancing IDL to work on clusters gives scientists access to increased performance in a familiar programming environment. The goal of this project was to enable IDL applications to benefit from both computing clusters as well as graphics processing units (GPUs) for accelerating data analysis tasks. The tool suite developed in this project enables scientists now to solve demanding data analysis problems in IDL that previously required specialized software, and it allows them to be solved orders of magnitude faster than on conventional PCs. The tool suite consists of three components: (1) TaskDL, a software tool that simplifies the creation and management of task farms, collections of tasks that can be processed independently and require only small amounts of data communication; (2) mpiDL, a tool that allows IDL developers to use the Message Passing Interface (MPI) inside IDL for problems that require large amounts of data to be exchanged among multiple processors; and (3) GPULib, a tool that simplifies the use of GPUs as mathematical coprocessors from within IDL. mpiDL is unique in its support for the full MPI standard and its support of a broad range of MPI implementations. GPULib is unique in enabling users to take advantage of an inexpensive piece of hardware, possibly already installed in their computer, and achieve orders of magnitude faster execution time for numerically complex algorithms. TaskDL enables the simple setup and management of task farms on compute clusters. The products developed in this project have the potential to interact, so one can build a cluster of PCs, each equipped with a GPU, and use mpiDL to communicate between the nodes and GPULib to accelerate the computations on each node.

The Curvilinear Relationship between State Neuroticism and Momentary Task Performance

PubMed Central

Debusscher, Jonas; Hofmans, Joeri; De Fruyt, Filip

2014-01-01

A daily diary and two experience sampling studies were carried out to investigate curvilinearity of the within-person relationship between state neuroticism and task performance, as well as the moderating effects of within-person variation in momentary job demands (i.e., work pressure and task complexity). In one, results showed that under high work pressure, the state neuroticism–task performance relationship was best described by an exponentially decreasing curve, whereas an inverted U-shaped curve was found for tasks low in work pressure, while in another study, a similar trend was visible for task complexity. In the final study, the state neuroticism–momentary task performance relationship was a linear one, and this relationship was moderated by momentary task complexity. Together, results from all three studies showed that it is important to take into account the moderating effects of momentary job demands because within-person variation in job demands affects the way in which state neuroticism relates to momentary levels of task performance. Specifically, we found that experiencing low levels of state neuroticism may be most beneficial in high demanding tasks, whereas more moderate levels of state neuroticism are optimal under low momentary job demands. PMID:25238547

Computer generated hologram from point cloud using graphics processor.

PubMed

Chen, Rick H-Y; Wilkinson, Timothy D

2009-12-20

Computer generated holography is an extremely demanding and complex task when it comes to providing realistic reconstructions with full parallax, occlusion, and shadowing. We present an algorithm designed for data-parallel computing on modern graphics processing units to alleviate the computational burden. We apply Gaussian interpolation to create a continuous surface representation from discrete input object points. The algorithm maintains a potential occluder list for each individual hologram plane sample to keep the number of visibility tests to a minimum. We experimented with two approximations that simplify and accelerate occlusion computation. It is observed that letting several neighboring hologram plane samples share visibility information on object points leads to significantly faster computation without causing noticeable artifacts in the reconstructed images. Computing a reduced sample set via nonuniform sampling is also found to be an effective acceleration technique.

Identifying the critical physical demanding tasks of paramedic work: Towards the development of a physical employment standard.

PubMed

Fischer, Steven L; Sinden, Kathryn E; MacPhee, Renee S

2017-11-01

Public safety related occupations including police, fire and military commonly apply physical employment standard (PES) to facilitate job matching, an approach to evaluate if candidates demonstrate acceptable physical capabilities as required to perform the job safely and effectively. In Canada, paramedics remain as one of the few public safety occupations without an evidence-based, validated PES. The purpose of this study was to document and describe the physical demands of paramedic work and to identify the most physically demanding tasks. These outcomes are essential to inform the design and development of an evidence-based PES for the paramedic sector. Physical demands of paramedic work were documented and described using a direct observation-based task analysis technique. Five paramedic's were trained to document the physical demands of their work, then applied their training to observe more than 90 calls over the course of 20 full 12-h work shifts. Physical demands data were then listed in a survey, administered service-wide, where 155 frontline paramedics identified critically demanding tasks and rank-ordered physical demands from not physically demanding to very strongly demanding. Critically important and physically demanding tasks were identified such as: transferring a patient; loading or unloading a stretcher in to or out of the ambulance; performing CPR; and, raising and lowering a stretcher. It is important that a paramedic-based PES evaluate a candidate's physical capabilities to perform the critical and physically demanding tasks identified in this study. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cognitive training with casual video games: points to consider

PubMed Central

Baniqued, Pauline L.; Kranz, Michael B.; Voss, Michelle W.; Lee, Hyunkyu; Cosman, Joshua D.; Severson, Joan; Kramer, Arthur F.

2014-01-01

Brain training programs have proliferated in recent years, with claims that video games or computer-based tasks can broadly enhance cognitive function. However, benefits are commonly seen only in trained tasks. Assessing generalized improvement and practicality of laboratory exercises complicates interpretation and application of findings. In this study, we addressed these issues by using active control groups, training tasks that more closely resemble real-world demands and multiple tests to determine transfer of training. We examined whether casual video games can broadly improve cognition, and selected training games from a study of the relationship between game performance and cognitive abilities. A total of 209 young adults were randomized into a working memory–reasoning group, an adaptive working memory–reasoning group, an active control game group, and a no-contact control group. Before and after 15 h of training, participants completed tests of reasoning, working memory, attention, episodic memory, perceptual speed, and self-report measures of executive function, game experience, perceived improvement, knowledge of brain training research, and game play outside the laboratory. Participants improved on the training games, but transfer to untrained tasks was limited. No group showed gains in reasoning, working memory, episodic memory, or perceptual speed, but the working memory–reasoning groups improved in divided attention, with better performance in an attention-demanding game, a decreased attentional blink and smaller trail-making costs. Perceived improvements did not differ across training groups and those with low reasoning ability at baseline showed larger gains. Although there are important caveats, our study sheds light on the mixed effects in the training and transfer literature and offers a novel and potentially practical training approach. Still, more research is needed to determine the real-world benefits of computer programs such as casual games. PMID:24432009

Cognitive training with casual video games: points to consider.

PubMed

Baniqued, Pauline L; Kranz, Michael B; Voss, Michelle W; Lee, Hyunkyu; Cosman, Joshua D; Severson, Joan; Kramer, Arthur F

2014-01-07

Brain training programs have proliferated in recent years, with claims that video games or computer-based tasks can broadly enhance cognitive function. However, benefits are commonly seen only in trained tasks. Assessing generalized improvement and practicality of laboratory exercises complicates interpretation and application of findings. In this study, we addressed these issues by using active control groups, training tasks that more closely resemble real-world demands and multiple tests to determine transfer of training. We examined whether casual video games can broadly improve cognition, and selected training games from a study of the relationship between game performance and cognitive abilities. A total of 209 young adults were randomized into a working memory-reasoning group, an adaptive working memory-reasoning group, an active control game group, and a no-contact control group. Before and after 15 h of training, participants completed tests of reasoning, working memory, attention, episodic memory, perceptual speed, and self-report measures of executive function, game experience, perceived improvement, knowledge of brain training research, and game play outside the laboratory. Participants improved on the training games, but transfer to untrained tasks was limited. No group showed gains in reasoning, working memory, episodic memory, or perceptual speed, but the working memory-reasoning groups improved in divided attention, with better performance in an attention-demanding game, a decreased attentional blink and smaller trail-making costs. Perceived improvements did not differ across training groups and those with low reasoning ability at baseline showed larger gains. Although there are important caveats, our study sheds light on the mixed effects in the training and transfer literature and offers a novel and potentially practical training approach. Still, more research is needed to determine the real-world benefits of computer programs such as casual games.

Resource-Efficient, Hierarchical Auto-Tuning of a Hybrid Lattice Boltzmann Computation on the Cray XT4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Computational Research Division, Lawrence Berkeley National Laboratory; NERSC, Lawrence Berkeley National Laboratory; Computer Science Department, University of California, Berkeley

2009-05-04

We apply auto-tuning to a hybrid MPI-pthreads lattice Boltzmann computation running on the Cray XT4 at National Energy Research Scientific Computing Center (NERSC). Previous work showed that multicore-specific auto-tuning can improve the performance of lattice Boltzmann magnetohydrodynamics (LBMHD) by a factor of 4x when running on dual- and quad-core Opteron dual-socket SMPs. We extend these studies to the distributed memory arena via a hybrid MPI/pthreads implementation. In addition to conventional auto-tuning at the local SMP node, we tune at the message-passing level to determine the optimal aspect ratio as well as the correct balance between MPI tasks and threads permore » MPI task. Our study presents a detailed performance analysis when moving along an isocurve of constant hardware usage: fixed total memory, total cores, and total nodes. Overall, our work points to approaches for improving intra- and inter-node efficiency on large-scale multicore systems for demanding scientific applications.« less

Efficient computation of photonic crystal waveguide modes with dispersive material.

PubMed

Schmidt, Kersten; Kappeler, Roman

2010-03-29

The optimization of PhC waveguides is a key issue for successfully designing PhC devices. Since this design task is computationally expensive, efficient methods are demanded. The available codes for computing photonic bands are also applied to PhC waveguides. They are reliable but not very efficient, which is even more pronounced for dispersive material. We present a method based on higher order finite elements with curved cells, which allows to solve for the band structure taking directly into account the dispersiveness of the materials. This is accomplished by reformulating the wave equations as a linear eigenproblem in the complex wave-vectors k. For this method, we demonstrate the high efficiency for the computation of guided PhC waveguide modes by a convergence analysis.

Subjective and psychophysiological indexes of listening effort in a competing-talker task.

PubMed

Mackersie, Carol L; Cones, Heather

2011-02-01

The effects of noise and other competing backgrounds on speech recognition performance are well documented. There is less information, however, on listening effort and stress experienced by listeners during a speech-recognition task that requires inhibition of competing sounds. The purpose was (a) to determine if psychophysiological indexes of listening effort were more sensitive than performance measures (percentage correct) obtained near ceiling level during a competing speech task, (b) to determine the relative sensitivity of four psychophysiological measures to changes in task demand, and (c) to determine the relationships between changes in psychophysiological measures and changes in subjective ratings of stress and workload. A repeated-measures experimental design was used to examine changes in performance, psychophysiological measures, and subjective ratings in response to increasing task demand. Fifteen adults with normal hearing participated in the study. The mean age of the participants was 27 (range: 24-54). Psychophysiological recordings of heart rate, skin conductance, skin temperature, and electromyographic (EMG) activity were obtained during listening tasks of varying demand. Materials from the Dichotic Digits Test were used to modulate task demand. The three levels of task demand were single digits presented to one ear (low-demand reference condition), single digits presented simultaneously to both ears (medium demand), and a series of two digits presented simultaneously to both ears (high demand). Participants were asked to repeat all the digits they heard, while psychophysiological activity was recorded simultaneously. Subjective ratings of task load were obtained after each condition using the National Aeronautics and Space Administration Task Load Index questionnaire. Repeated-measures analyses of variance were completed for each measure using task demand and session as factors. Mean performance was higher than 96% for all listening tasks. There was no significant change in performance across listening conditions for any listener. There was, however, a significant increase in mean skin conductance and EMG activity as task demand increased. Heart rate and skin temperature did not change significantly. There was no strong association between subjective and psychophysiological measures, but all participants with mean normalized effort ratings of greater than 4.5 (i.e., effort increased by a factor of at least 4.5) showed significant changes in skin conductance. Even in the absence of substantial performance changes, listeners may experience changes in subjective and psychophysiological responses consistent with the activation of a stress response. Skin conductance appears to be the most promising measure for evaluating individual changes in psychophysiological responses during listening tasks. American Academy of Audiology.

Autonomic Nervous System Responses to Hearing-Related Demand and Evaluative Threat.

PubMed

Mackersie, Carol L; Kearney, Lucia

2017-10-12

This paper consists of 2 parts. The purpose of Part 1 was to review the potential influence of internal (person-related) factors on listening effort. The purpose of Part 2 was to present, in support of Part 1, preliminary data illustrating the interactive effects of an external factor (task demand) and an internal factor (evaluative threat) on autonomic nervous system measures. For Part 1, we provided a brief narrative review of motivation and stress as modulators of listening effort. For Part 2, we described preliminary data from a study using a repeated-measures (2 × 2) design involving manipulations of task demand (high, low) and evaluative threat (high, low). The low-demand task consisted of repetition of sentences from a narrative. The high-demand task consisted of answering questions about the narrative, requiring both comprehension and recall. During the high evaluative threat condition, participants were filmed and told that their video recordings would be evaluated by a panel of experts. During the low evaluative threat condition, no filming occurred; participants were instructed to "do your best." Skin conductance (sympathetic nervous system activity) and heart rate variability (HRV, parasympathetic activity) were measured during the listening tasks. The HRV measure was the root mean square of successive differences of adjacent interbeat intervals. Twelve adults with hearing loss participated. Skin conductance increased and HRV decreased relative to baseline (no task) for all listening conditions. Skin conductance increased significantly with an increase in evaluative threat, but only for the more demanding task. There was no significant change in HRV in response to increasing evaluative threat or task demand. Listening effort may be influenced by factors other than task difficulty, as reviewed in Part 1. This idea is supported by the preliminary data indicating that the sympathetic nervous system response to task demand is modulated by social evaluative threat. More work is needed to determine the relative contributions of motivation and emotional stress on physiological responses during listening tasks.

CAD Services: an Industry Standard Interface for Mechanical CAD Interoperability

NASA Technical Reports Server (NTRS)

Claus, Russell; Weitzer, Ilan

2002-01-01

Most organizations seek to design and develop new products in increasingly shorter time periods. At the same time, increased performance demands require a team-based multidisciplinary design process that may span several organizations. One approach to meet these demands is to use 'Geometry Centric' design. In this approach, design engineers team their efforts through one united representation of the design that is usually captured in a CAD system. Standards-based interfaces are critical to provide uniform, simple, distributed services that enable the 'Geometry Centric' design approach. This paper describes an industry-wide effort, under the Object Management Group's (OMG) Manufacturing Domain Task Force, to define interfaces that enable the interoperability of CAD, Computer Aided Manufacturing (CAM), and Computer Aided Engineering (CAE) tools. This critical link to enable 'Geometry Centric' design is called: Cad Services V1.0. This paper discusses the features of this standard and proposed application.

N-CET: Network-Centric Exploitation and Tracking

DTIC Science & Technology

2009-10-01

DATES COVERED (From - To) October 2008 – August 2009 4 . TITLE AND SUBTITLE N-CET: NETWORK – CENTRIC EXPLOITATION AND TRACKING 5a. CONTRACT NUMBER...At the core of N-CET are information management services that decouple data producers and consumers , allowing reconfiguration to suit mission needs...Shown around the head-node are different pieces of hardware including the Sony PlayStation R©3 (PS3) nodes used for computationally demanding tasks

Subjective and psychophysiological indices of listening effort in a competing-talker task

PubMed Central

Mackersie, Carol L.; Cones, Heather

2010-01-01

Background The effects of noise and other competing backgrounds on speech recognition performance are well documented. There is less information, however, on listening effort and stress experienced by listeners during a speech recognition task that requires inhibition of competing sounds. Purpose The purpose was a) to determine if psychophysiological indices of listening effort were more sensitive than performance measures (percentage correct) obtained near ceiling level during a competing speech task b) to determine the relative sensitivity of four psychophysiological measures to changes in task demand and c) to determine the relationships between changes in psychophysiological measures and changes in subjective ratings of stress and workload. Research Design A repeated-measures experimental design was used to examine changes in performance, psychophysiological measures, and subjective ratings in response to increasing task demand. Study Sample Fifteen adults with normal hearing participated in the study. The mean age of the participants was 27 (range: 24–54). Data Collection and Analysis Psychophysiological recordings of heart rate, skin conductance, skin temperature, and electromyographic activity (EMG) were obtained during listening tasks of varying demand. Materials from the Dichotic Digits Test were used to modulate task demand. The three levels of tasks demand were: single digits presented to one ear (low-demand reference condition), single digits presented simultaneously to both ears (medium demand), and a series of two digits presented simultaneously to both ears (high demand). Participants were asked to repeat all the digits they heard while psychophysiological activity was recorded simultaneously. Subjective ratings of task load were obtained after each condition using the NASA-TLX questionnaire. Repeated-measures analyses of variance were completed for each measure using task demand and session as factors. Results Mean performance was higher than 96% for all listening tasks. There was no significant change in performance across listening conditions for any listener. There was, however, a significant increase in mean skin conductance and EMG activity as task demand increased. Heart rate and skin temperature did not change significantly. There was no strong association between subjective and psychophysiological measures, but all participants with mean normalized effort ratings of greater than 4.5 (i.e. effort increased by a factor of at least 4.5) showed significant changes in skin conductance. Conclusions Even in the absence of substantial performance changes, listeners may experience changes in subjective and psychophysiological responses consistent with activation of a stress response. Skin conductance appears to be the most promising measure for evaluating individual changes in psychophysiological responses during listening tasks. PMID:21463566

Developmental changes in using verbal self-cueing in task-switching situations: the impact of task practice and task-sequencing demands.

PubMed

Kray, Jutta; Gaspard, Hanna; Karbach, Julia; Blaye, Agnès

2013-01-01

In this study we examined whether developmental changes in using verbal self-cueing for task-goal maintenance are dependent on the amount of task practice and task-sequencing demands. To measure task-goal maintenance we applied a switching paradigm in which children either performed only task A or B in single-task blocks or switched between them on every second trial in mixed-task blocks. Task-goal maintenance was determined by comparing the performance between both blocks (mixing costs). The influence of verbal self-cueing was measured by instructing children to either name the next task aloud or not to verbalize during task preparation. Task-sequencing demands were varied between groups whereas one group received spatial task cues to support keeping track of the task sequence, while the other group did not. We also varied by the amount of prior practice in task switching while one group of participants practiced task switching first, before performing the task naming in addition, and the other group did it vice versa. Results of our study investigating younger (8-10 years) and older children (11-13 years) revealed no age differences in beneficial effects of verbal self-cueing. In line with previous findings, children showed reduced mixing costs under task-naming instructions and under conditions of low task-sequence demands (with the presence of spatial task cues). Our results also indicated that these benefits were only obtained for those groups of children that first received practice in task switching alone with no additional verbalization instruction. These findings suggest that internal task-cueing strategies can be efficiently used in children but only if they received prior practice in the underlying task so that demands on keeping and coordinating various instructions are reduced. Moreover, children benefitted from spatial task cues for better task-goal maintenance only if no verbal task-cueing strategy was introduced first.

Computer support for cooperative tasks in Mission Operations Centers

NASA Technical Reports Server (NTRS)

Fox, Jeffrey; Moore, Mike

1994-01-01

Traditionally, spacecraft management has been performed by fixed teams of operators in Mission Operations Centers. The team cooperatively: (1) ensures that payload(s) on spacecraft perform their work; and (2) maintains the health and safety of the spacecraft through commanding and monitoring the spacecraft's subsystems. In the future, the task demands will increase and overload the operators. This paper describes the traditional spacecraft management environment and describes a new concept in which groupware will be used to create a Virtual Mission Operations Center. Groupware tools will be used to better utilize available resources through increased automation and dynamic sharing of personnel among missions.

Econophysics of a ranked demand and supply resource allocation problem

NASA Astrophysics Data System (ADS)

Priel, Avner; Tamir, Boaz

2018-01-01

We present a two sided resource allocation problem, between demands and supplies, where both parties are ranked. For example, in Big Data problems where a set of different computational tasks is divided between a set of computers each with its own resources, or between employees and employers where both parties are ranked, the employees by their fitness and the employers by their package benefits. The allocation process can be viewed as a repeated game where in each iteration the strategy is decided by a meta-rule, based on the ranks of both parties and the results of the previous games. We show the existence of a phase transition between an absorbing state, where all demands are satisfied, and an active one where part of the demands are always left unsatisfied. The phase transition is governed by the ratio between supplies and demand. In a job allocation problem we find positive correlation between the rank of the workers and the rank of the factories; higher rank workers are usually allocated to higher ranked factories. These all suggest global emergent properties stemming from local variables. To demonstrate the global versus local relations, we introduce a local inertial force that increases the rank of employees in proportion to their persistence time in the same factory. We show that such a local force induces non trivial global effects, mostly to benefit the lower ranked employees.

Age-Related Differences in the Reliance on Executive Control in Working Memory: Role of Task Demand

PubMed Central

Isingrini, Michel; Angel, Lucie; Fay, Séverine; Taconnat, Laurence; Lemaire, Patrick; Bouazzaoui, Badiâa

2015-01-01

We examined the hypothesis that age-related differences in the reliance on executive control may be better explained by variations of task demand than by a mechanism specifically linked to aging. To this end, we compared the relationship between the performance of young and older adults on two executive functioning tests and an updating working-memory task with different load levels. The results revealed a significant interaction between age, task demand, and individual executive capacities, indicating that executive resources were only involved at lower loads in older adults, and only at higher loads in young adults. Overall, the results are not consistent with the proposition that cognition places greater demand on executive control in older adults. However, they support the view that how much young and older adults rely on executive control to accomplish cognitive tasks depends on task demand. Finally, interestingly these results are consistent with the CRUNCH model accounting for age-related differences in brain activations. PMID:26700019

Age-Related Differences in the Reliance on Executive Control in Working Memory: Role of Task Demand.

PubMed

Isingrini, Michel; Angel, Lucie; Fay, Séverine; Taconnat, Laurence; Lemaire, Patrick; Bouazzaoui, Badiâa

2015-01-01

We examined the hypothesis that age-related differences in the reliance on executive control may be better explained by variations of task demand than by a mechanism specifically linked to aging. To this end, we compared the relationship between the performance of young and older adults on two executive functioning tests and an updating working-memory task with different load levels. The results revealed a significant interaction between age, task demand, and individual executive capacities, indicating that executive resources were only involved at lower loads in older adults, and only at higher loads in young adults. Overall, the results are not consistent with the proposition that cognition places greater demand on executive control in older adults. However, they support the view that how much young and older adults rely on executive control to accomplish cognitive tasks depends on task demand. Finally, interestingly these results are consistent with the CRUNCH model accounting for age-related differences in brain activations.

The UCLA MEDLARS Computer System *

PubMed Central

Garvis, Francis J.

1966-01-01

Under a subcontract with UCLA the Planning Research Corporation has changed the MEDLARS system to make it possible to use the IBM 7094/7040 direct-couple computer instead of the Honeywell 800 for demand searches. The major tasks were the rewriting of the programs in COBOL and copying of the stored information on the narrower tapes that IBM computers require. (In the future NLM will copy the tapes for IBM computer users.) The differences in the software required by the two computers are noted. Major and costly revisions would be needed to adapt the large MEDLARS system to the smaller IBM 1401 and 1410 computers. In general, MEDLARS is transferrable to other computers of the IBM 7000 class, the new IBM 360, and those of like size, such as the CDC 1604 or UNIVAC 1108, although additional changes are necessary. Potential future improvements are suggested. PMID:5901355

Decoupling of reaction time-related default mode network activity with cognitive demand.

PubMed

Barber, Anita D; Caffo, Brian S; Pekar, James J; Mostofsky, Stewart H

2017-06-01

Reaction Time (RT) is associated with increased amplitude of the Blood Oxygen-Level Dependent (BOLD) response in task positive regions. Few studies have focused on whether opposing RT-related suppression of task activity also occurs. The current study used two Go/No-go tasks with different cognitive demands to examine regions that showed greater BOLD suppression for longer RT trials. These RT-related suppression effects occurred within the DMN and were task-specific, localizing to separate regions for the two tasks. In the task requiring working memory, RT-related de-coupling of the DMN occurred. This was reflected by opposing RT-BOLD effects for different DMN regions, as well as by reduced positive RT-related Psycho-Physiological Interaction (PPI) connectivity within the DMN and a lack of negative RT-related PPI connectivity between DMN and task positive regions. The results suggest that RT-related DMN suppression is task-specific. RT-related de-coupling of the DMN with more complex task demands may contribute to lapses of attention and performance decrements that occur during cognitively-demanding tasks.

Neuroticism related differences in the functional neuroanatomical correlates of multitasking. An fMRI study.

PubMed

Szameitat, Andre J; Saylik, Rahmi; Parton, Andrew

2016-12-02

It is known that neuroticism impairs cognitive performance mostly in difficult tasks, but not so much in easier tasks. One pervasive situation of this type is multitasking, in which the combination of two simple tasks creates a highly demanding dual-task, and consequently high neurotics show higher dual-task costs than low neurotics. However, the functional neuroanatomical correlates of these additional performance impairments in high neurotics are unknown. To test for this, we assessed brain activity by means of functional magnetic resonance imaging (fMRI) in 17 low and 15 high neurotics while they were performing a demanding dual-task and the less demanding component tasks as single-tasks. Behavioural results showed that performance (response times and error rates) was lower in the dual-task than in the single-tasks (dual-task costs), and that these dual-task costs were significantly higher in high neurotics. Imaging data showed that high neurotics showed less dual-task specific activation in lateral (mainly middle frontal gyrus) and medial prefrontal cortices. We conclude that high levels of neuroticism impair behavioural performance in demanding tasks, and that this impairment is accompanied by reduced activation of the task-associated brain areas. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Freezing degrees of freedom under stress: kinematic evidence of constrained movement strategies.

PubMed

Higuchi, Takahiro; Imanaka, Kuniyasu; Hatayama, Toshiteru

2002-12-01

The present study investigated the effect of psychological stress imposed on movement kinematics in a computer-simulated batting task involving a backward and forward swing of the forearm. The psychological stress was imposed by a mild electric stimulus following poor performance. Fourteen participants hit a moving ball with a horizontal lever and aimed at a distant target with as much accuracy as possible. The kinematic characteristics appearing under stress were delay of movement initiation, small amplitude of movement and low variability of spatial kinematic events between trials. These features were also found in previous studies in which the experimental task required high accuracy. The characteristic kinematics evident in the present study suggested that the movement strategies adopted by the stressed participants were similar to those that appear under high accuracy demand. Moreover, a correlation analysis between the onset times of kinematic events revealed that temporally consistent movements were reproduced under stress. Taken together, the present findings demonstrated that, under psychological stress, movement strategies tend to shift toward the production of more constrained trajectories, as is seen under conditions of high accuracy demand, even though the difficulty of the task itself does not change. Copyright 2002 Elsevier Science B.V.

Adaptive Automation Triggered by EEG-Based Mental Workload Index: A Passive Brain-Computer Interface Application in Realistic Air Traffic Control Environment.

PubMed

Aricò, Pietro; Borghini, Gianluca; Di Flumeri, Gianluca; Colosimo, Alfredo; Bonelli, Stefano; Golfetti, Alessia; Pozzi, Simone; Imbert, Jean-Paul; Granger, Géraud; Benhacene, Raïlane; Babiloni, Fabio

2016-01-01

Adaptive Automation (AA) is a promising approach to keep the task workload demand within appropriate levels in order to avoid both the under - and over-load conditions, hence enhancing the overall performance and safety of the human-machine system. The main issue on the use of AA is how to trigger the AA solutions without affecting the operative task. In this regard, passive Brain-Computer Interface (pBCI) systems are a good candidate to activate automation, since they are able to gather information about the covert behavior (e.g., mental workload) of a subject by analyzing its neurophysiological signals (i.e., brain activity), and without interfering with the ongoing operational activity. We proposed a pBCI system able to trigger AA solutions integrated in a realistic Air Traffic Management (ATM) research simulator developed and hosted at ENAC (É cole Nationale de l'Aviation Civile of Toulouse, France). Twelve Air Traffic Controller (ATCO) students have been involved in the experiment and they have been asked to perform ATM scenarios with and without the support of the AA solutions. Results demonstrated the effectiveness of the proposed pBCI system, since it enabled the AA mostly during the high-demanding conditions (i.e., overload situations) inducing a reduction of the mental workload under which the ATCOs were operating. On the contrary, as desired, the AA was not activated when workload level was under the threshold, to prevent too low demanding conditions that could bring the operator's workload level toward potentially dangerous conditions of underload.

Adaptive Automation Triggered by EEG-Based Mental Workload Index: A Passive Brain-Computer Interface Application in Realistic Air Traffic Control Environment

PubMed Central

Aricò, Pietro; Borghini, Gianluca; Di Flumeri, Gianluca; Colosimo, Alfredo; Bonelli, Stefano; Golfetti, Alessia; Pozzi, Simone; Imbert, Jean-Paul; Granger, Géraud; Benhacene, Raïlane; Babiloni, Fabio

2016-01-01

Adaptive Automation (AA) is a promising approach to keep the task workload demand within appropriate levels in order to avoid both the under- and over-load conditions, hence enhancing the overall performance and safety of the human-machine system. The main issue on the use of AA is how to trigger the AA solutions without affecting the operative task. In this regard, passive Brain-Computer Interface (pBCI) systems are a good candidate to activate automation, since they are able to gather information about the covert behavior (e.g., mental workload) of a subject by analyzing its neurophysiological signals (i.e., brain activity), and without interfering with the ongoing operational activity. We proposed a pBCI system able to trigger AA solutions integrated in a realistic Air Traffic Management (ATM) research simulator developed and hosted at ENAC (École Nationale de l'Aviation Civile of Toulouse, France). Twelve Air Traffic Controller (ATCO) students have been involved in the experiment and they have been asked to perform ATM scenarios with and without the support of the AA solutions. Results demonstrated the effectiveness of the proposed pBCI system, since it enabled the AA mostly during the high-demanding conditions (i.e., overload situations) inducing a reduction of the mental workload under which the ATCOs were operating. On the contrary, as desired, the AA was not activated when workload level was under the threshold, to prevent too low demanding conditions that could bring the operator's workload level toward potentially dangerous conditions of underload. PMID:27833542

The impact of task demand on visual word recognition.

PubMed

Yang, J; Zevin, J

2014-07-11

The left occipitotemporal cortex has been found sensitive to the hierarchy of increasingly complex features in visually presented words, from individual letters to bigrams and morphemes. However, whether this sensitivity is a stable property of the brain regions engaged by word recognition is still unclear. To address the issue, the current study investigated whether different task demands modify this sensitivity. Participants viewed real English words and stimuli with hierarchical word-likeness while performing a lexical decision task (i.e., to decide whether each presented stimulus is a real word) and a symbol detection task. General linear model and independent component analysis indicated strong activation in the fronto-parietal and temporal regions during the two tasks. Furthermore, the bilateral inferior frontal gyrus and insula showed significant interaction effects between task demand and stimulus type in the pseudoword condition. The occipitotemporal cortex showed strong main effects for task demand and stimulus type, but no sensitivity to the hierarchical word-likeness was found. These results suggest that different task demands on semantic, phonological and orthographic processes can influence the involvement of the relevant regions during visual word recognition. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Age Differences in the Transfer and Maintenance of Practice-Induced Improvements in Task Switching: The Impact of Working-Memory and Inhibition Demands

PubMed Central

Kray, Jutta; Fehér, Balázs

2017-01-01

Recent aging studies on training in task switching found that older adults showed larger improvements to an untrained switching task as younger adults do. However, less clear is what type of cognitive control processes can explain these training gains as participants were trained with a particular type of switching task including bivalent stimuli, requiring high inhibition demands, and no task cues helping them keeping track of the task sequence, and by this, requiring high working-memory (WM) demands. The aims of this study were first to specify whether inhibition, WM, or switching demands are critical for the occurrence of transfer and whether this transfer depends on the degree of overlap between training and transfer situation; and second to assess whether practiced-induced gains in task switching can be maintained over a longer period of time. To this end, we created five training conditions that varied in switching (switching vs. single task training), inhibition (switching training with bivalent or univalent stimuli), and WM demands (switching training with or without task cues). We investigated 81 younger adults and 82 older adults with a pretest-training-posttest design and a follow-up measurement after 6 months. Results indicated that all training and age groups showed improvements in task switching and a differential effect of training condition on improvements to an untrained switching task in younger and older adults. For younger adults, we found larger improvements in task switching for the switching groups than the single-task training group independently of inhibition and WM demands, suggesting that practice in switching is most critical. However, these benefits disappeared after 6 months. In contrast, for older adults training groups practicing task switching under high inhibition demands showed larger improvements to untrained switching tasks than the other groups. Moreover, these benefits were maintained over time. We also found that the transfer of benefits in task switching was larger with greater overlap between training and transfer situation. However, results revealed no evidence for transfer to other untrained cognitive task. Overall, the findings suggest that training in resolving interference while switching between two tasks is most critical for the occurrence of transfer in the elderly. PMID:28367135

Quantitative muscle strength testing: a comparison of job strength requirements and actual worker strength among military technicians.

PubMed

Pedersen, D M; Clark, J A; Johns, R E; White, G L; Hoffman, S

1989-01-01

In this study the authors investigate the percentage of mismatch between job demands and worker physical capacity in Utah National Guard mechanics. This population had demonstrated a higher incidence of low back trouble than other job descriptions reviewed. The authors utilized onsite still and videotape photography and a computerized biomechanical strength prediction model to assess loads on the lumbosacral spine due to various job tasks. Job demands were then compared to the actual physical capacity of the individual workers based on static strength testing in job-related positions. A load cell on the testing apparatus entered the force generated into a computer which averaged the force of the last three seconds of a five-second lift. It was determined that as much as a 38% mismatch existed within this population for some job tasks which these workers were exposed to. Suggestions for preventing job-related low back cumulative trauma disorders are presented, including: engineering redesign, worker selection programs, work hardening, and others.

Self-estimates of distractibility as related to performance decrement on a task requiring sustained attention.

DOT National Transportation Integrated Search

1972-07-01

Increasing automation of air traffic control tasks may have the undesirable side effect of increased monotony as a result of the anticipated reduction in task demands. 50 subjects performed a monotonous, but perceptually demanding task, for approxima...

Attentional demands and postural recovery: the effects of aging.

PubMed

Brown, L A; Shumway-Cook, A; Woollacott, M H

1999-04-01

Cognitive demands associated with balance and locomotion may contribute to the incidence of falling among older adults. This study addressed issues related to the effects of aging on the attentional demands of recovering from an external disturbance to balance. This research also investigated whether performing a secondary cognitive task differentially affects postural recovery in young versus older adults. Fifteen young and 10 healthy older adults were exposed to a series of balance disturbances. Attentional demands were assessed using a dual task paradigm where postural recovery served as the primary task, and counting backwards served as a concurrent secondary cognitive task. The effect of the counting task was assessed by comparing kinematic variables related to feet-in-place and stepping recovery strategies. Recovering upright stance was found to be attentionally demanding in both age groups. The type of recovery strategy did not influence attentional demands in young adults; however, a hierarchy of increasing attentional demands between the ankle strategy and compensatory stepping was apparent among older adults. In addition, stepping appears to be more attentionally demanding for older adults than for younger adults. Counting backwards did not affect the type of strategy used; however, it did affect the kinematics of stepping. For both age groups, steps occurred when the center of mass was located in a more central location within the base of support when the secondary task was added. The ability to recover a stable posture following an external perturbation is more attentionally demanding for older adults than for younger adults. This would suggest that for some older adults, an increased risk for loss of balance and falls may result if sufficient attentional resources are not allocated to the task of postural recovery.

Computational models of the Posner simple and choice reaction time tasks

PubMed Central

Feher da Silva, Carolina; Baldo, Marcus V. C.

2015-01-01

The landmark experiments by Posner in the late 1970s have shown that reaction time (RT) is faster when the stimulus appears in an expected location, as indicated by a cue; since then, the so-called Posner task has been considered a “gold standard” test of spatial attention. It is thus fundamental to understand the neural mechanisms involved in performing it. To this end, we have developed a Bayesian detection system and small integrate-and-fire neural networks, which modeled sensory and motor circuits, respectively, and optimized them to perform the Posner task under different cue type proportions and noise levels. In doing so, main findings of experimental research on RT were replicated: the relative frequency effect, suboptimal RTs and significant error rates due to noise and invalid cues, slower RT for choice RT tasks than for simple RT tasks, fastest RTs for valid cues and slowest RTs for invalid cues. Analysis of the optimized systems revealed that the employed mechanisms were consistent with related findings in neurophysiology. Our models predict that (1) the results of a Posner task may be affected by the relative frequency of valid and neutral trials, (2) in simple RT tasks, input from multiple locations are added together to compose a stronger signal, and (3) the cue affects motor circuits more strongly in choice RT tasks than in simple RT tasks. In discussing the computational demands of the Posner task, attention has often been described as a filter that protects the nervous system, whose capacity is limited, from information overload. Our models, however, reveal that the main problems that must be overcome to perform the Posner task effectively are distinguishing signal from external noise and selecting the appropriate response in the presence of internal noise. PMID:26190997

Ergonomic Redesign of an Industrial Control Panel.

PubMed

Raeisi, S; Osqueizadeh, R; Maghsoudipour, M; Jafarpisheh, A S

2016-07-01

Operator's role in industrial control centers takes place in time, which is one of the most important determinants of whether an expected action is going to be successful or not. In certain situations, due to the complex nature of the work, the existing interfaces and already prepared procedures do not meet the dynamic requirements of operator's cognitive demands, making the control tasks unnecessarily difficult. This study was conducted to identify ergonomic issues with a specific industrial control panel, and redesign its layout and elements to enhance its usability. Task and link analysis methodologies were implemented. All essential functions and supporting operations were identified at the required trivial levels. Next, the weight of any possible link between the elements of the panel was computed as a composite index of frequency and importance. Finally, all components were rearranged within a new layout, and a computerized mockup was generated. A total of 8 primary tasks was identified, including 4 system failure handling tasks, switching between manual and automated modes, and 3 types of routine vigilance and control tasks. These tasks were broken down into 28 functions and 145 supporting operations, accordingly. Higher link values were observed between hand rest position and 2 elements. Also, 6 other components showed robust linkages. In conclusion, computer modeling can reduce the likelihood of accidents and near misses in industrial control rooms by considering the operators' misperception or mental burden and correcting poor design of the panels and inappropriate task allocation.

Cognitive Demands Influence Lower Extremity Mechanics During a Drop Vertical Jump Task in Female Athletes.

PubMed

Almonroeder, Thomas Gus; Kernozek, Thomas; Cobb, Stephen; Slavens, Brooke; Wang, Jinsung; Huddleston, Wendy

2018-05-01

Study Design Cross-sectional study. Background The drop vertical jump task is commonly used to screen for anterior cruciate ligament injury risk; however, its predictive validity is limited. The limited predictive validity of the drop vertical jump task may be due to not imposing the cognitive demands that reflect sports participation. Objectives To investigate the influence of additional cognitive demands on lower extremity mechanics during execution of the drop vertical jump task. Methods Twenty uninjured women (age range, 18-25 years) were required to perform the standard drop vertical jump task, as well as drop vertical jumps that included additional cognitive demands. The additional cognitive demands were related to attending to an overhead goal (ball suspended overhead) and/or temporal constraints on movement selection (decision making). Three-dimensional ground reaction forces and lower extremity mechanics were compared between conditions. Results The inclusion of the overhead goal resulted in higher peak vertical ground reaction forces and lower peak knee flexion angles in comparison to the standard drop vertical jump task. In addition, participants demonstrated greater peak knee abduction angles when trials incorporated temporal constraints on decision making and/or required participants to attend to an overhead goal, in comparison to the standard drop vertical jump task. Conclusion Imposing additional cognitive demands during execution of the drop vertical jump task influenced lower extremity mechanics in a manner that suggested increased loading of the anterior cruciate ligament. Tasks utilized in anterior cruciate ligament injury risk screening may benefit from more closely reflecting the cognitive demands of the sports environment. J Orthop Sports Phys Ther 2018;48(5):381-387. Epub 10 Jan 2018. doi:10.2519/jospt.2018.7739.

Achieving production-level use of HEP software at the Argonne Leadership Computing Facility

NASA Astrophysics Data System (ADS)

Uram, T. D.; Childers, J. T.; LeCompte, T. J.; Papka, M. E.; Benjamin, D.

2015-12-01

HEP's demand for computing resources has grown beyond the capacity of the Grid, and these demands will accelerate with the higher energy and luminosity planned for Run II. Mira, the ten petaFLOPs supercomputer at the Argonne Leadership Computing Facility, is a potentially significant compute resource for HEP research. Through an award of fifty million hours on Mira, we have delivered millions of events to LHC experiments by establishing the means of marshaling jobs through serial stages on local clusters, and parallel stages on Mira. We are running several HEP applications, including Alpgen, Pythia, Sherpa, and Geant4. Event generators, such as Sherpa, typically have a split workload: a small scale integration phase, and a second, more scalable, event-generation phase. To accommodate this workload on Mira we have developed two Python-based Django applications, Balsam and ARGO. Balsam is a generalized scheduler interface which uses a plugin system for interacting with scheduler software such as HTCondor, Cobalt, and TORQUE. ARGO is a workflow manager that submits jobs to instances of Balsam. Through these mechanisms, the serial and parallel tasks within jobs are executed on the appropriate resources. This approach and its integration with the PanDA production system will be discussed.

Unconventional methods of imaging: computational microscopy and compact implementations

NASA Astrophysics Data System (ADS)

McLeod, Euan; Ozcan, Aydogan

2016-07-01

In the past two decades or so, there has been a renaissance of optical microscopy research and development. Much work has been done in an effort to improve the resolution and sensitivity of microscopes, while at the same time to introduce new imaging modalities, and make existing imaging systems more efficient and more accessible. In this review, we look at two particular aspects of this renaissance: computational imaging techniques and compact imaging platforms. In many cases, these aspects go hand-in-hand because the use of computational techniques can simplify the demands placed on optical hardware in obtaining a desired imaging performance. In the first main section, we cover lens-based computational imaging, in particular, light-field microscopy, structured illumination, synthetic aperture, Fourier ptychography, and compressive imaging. In the second main section, we review lensfree holographic on-chip imaging, including how images are reconstructed, phase recovery techniques, and integration with smart substrates for more advanced imaging tasks. In the third main section we describe how these and other microscopy modalities have been implemented in compact and field-portable devices, often based around smartphones. Finally, we conclude with some comments about opportunities and demand for better results, and where we believe the field is heading.

Adventures in Private Cloud: Balancing Cost and Capability at the CloudSat Data Processing Center

NASA Astrophysics Data System (ADS)

Partain, P.; Finley, S.; Fluke, J.; Haynes, J. M.; Cronk, H. Q.; Miller, S. D.

2016-12-01

Since the beginning of the CloudSat Mission in 2006, The CloudSat Data Processing Center (DPC) at the Cooperative Institute for Research in the Atmosphere (CIRA) has been ingesting data from the satellite and other A-Train sensors, producing data products, and distributing them to researchers around the world. The computing infrastructure was specifically designed to fulfill the requirements as specified at the beginning of what nominally was a two-year mission. The environment consisted of servers dedicated to specific processing tasks in a rigid workflow to generate the required products. To the benefit of science and with credit to the mission engineers, CloudSat has lasted well beyond its planned lifetime and is still collecting data ten years later. Over that period requirements of the data processing system have greatly expanded and opportunities for providing value-added services have presented themselves. But while demands on the system have increased, the initial design allowed for very little expansion in terms of scalability and flexibility. The design did change to include virtual machine processing nodes and distributed workflows but infrastructure management was still a time consuming task when system modification was required to run new tests or implement new processes. To address the scalability, flexibility, and manageability of the system Cloud computing methods and technologies are now being employed. The use of a public cloud like Amazon Elastic Compute Cloud or Google Compute Engine was considered but, among other issues, data transfer and storage cost becomes a problem especially when demand fluctuates as a result of reprocessing and the introduction of new products and services. Instead, the existing system was converted to an on premises private Cloud using the OpenStack computing platform and Ceph software defined storage to reap the benefits of the Cloud computing paradigm. This work details the decisions that were made, the benefits that have been realized, the difficulties that were encountered and issues that still exist.

Pay attention to your manipulation checks! Reward impact on cardiac reactivity is moderated by task context.

PubMed

Richter, Michael

2010-05-01

Two experiments assessed the moderating impact of task context on the relationship between reward and cardiovascular response. Randomly assigned to the cells of a 2 (task context: reward vs. demand) x 2 (reward value: low vs. high) between-persons design, participants performed either a memory task with an unclear performance standard (Experiment 1) or a visual scanning task with an unfixed performance standard (Experiment 2). Before performing the task--where participants could earn either a low or a high reward--participants responded to questions about either task reward or task demand. In accordance with the theoretical predictions derived from Wright's (1996) integrative model, reactivity of pre-ejection period increased with reward value if participants had rated aspects of task reward before performing the task. If they had rated task demand, pre-ejection period did not differ as a function of reward. Copyright 2010 Elsevier B.V. All rights reserved.

Development of Physical Employment Standards for the Royal Australian Navy: Validation of Identified Whole-of-ship Tasks

DTIC Science & Technology

2014-11-01

to determining individual CS tasks, this partially satisfied Navy’s request to quantify the physical demands of the course in order to draw parity ...will enable comparison between task demands on the course and during on-board duties. These data will be used to determine whether there is parity ...between the physical and physiological demands of the ACSC (or components of it) and CS tasks performed on-board each platform. If parity is drawn

A derived heuristics based multi-objective optimization procedure for micro-grid scheduling

NASA Astrophysics Data System (ADS)

Li, Xin; Deb, Kalyanmoy; Fang, Yanjun

2017-06-01

With the availability of different types of power generators to be used in an electric micro-grid system, their operation scheduling as the load demand changes with time becomes an important task. Besides satisfying load balance constraints and the generator's rated power, several other practicalities, such as limited availability of grid power and restricted ramping of power output from generators, must all be considered during the operation scheduling process, which makes it difficult to decide whether the optimization results are accurate and satisfactory. In solving such complex practical problems, heuristics-based customized optimization algorithms are suggested. However, due to nonlinear and complex interactions of variables, it is difficult to come up with heuristics in such problems off-hand. In this article, a two-step strategy is proposed in which the first task deciphers important heuristics about the problem and the second task utilizes the derived heuristics to solve the original problem in a computationally fast manner. Specifically, the specific operation scheduling is considered from a two-objective (cost and emission) point of view. The first task develops basic and advanced level knowledge bases offline from a series of prior demand-wise optimization runs and then the second task utilizes them to modify optimized solutions in an application scenario. Results on island and grid connected modes and several pragmatic formulations of the micro-grid operation scheduling problem clearly indicate the merit of the proposed two-step procedure.

Task-dependent recurrent dynamics in visual cortex

PubMed Central

Tajima, Satohiro; Koida, Kowa; Tajima, Chihiro I; Suzuki, Hideyuki; Aihara, Kazuyuki; Komatsu, Hidehiko

2017-01-01

The capacity for flexible sensory-action association in animals has been related to context-dependent attractor dynamics outside the sensory cortices. Here, we report a line of evidence that flexibly modulated attractor dynamics during task switching are already present in the higher visual cortex in macaque monkeys. With a nonlinear decoding approach, we can extract the particular aspect of the neural population response that reflects the task-induced emergence of bistable attractor dynamics in a neural population, which could be obscured by standard unsupervised dimensionality reductions such as PCA. The dynamical modulation selectively increases the information relevant to task demands, indicating that such modulation is beneficial for perceptual decisions. A computational model that features nonlinear recurrent interaction among neurons with a task-dependent background input replicates the key properties observed in the experimental data. These results suggest that the context-dependent attractor dynamics involving the sensory cortex can underlie flexible perceptual abilities. DOI: http://dx.doi.org/10.7554/eLife.26868.001 PMID:28737487

Attentional Demand of a Virtual Reality-Based Reaching Task in Nondisabled Older Adults.

PubMed

Chen, Yi-An; Chung, Yu-Chen; Proffitt, Rachel; Wade, Eric; Winstein, Carolee

2015-12-01

Attention during exercise is known to affect performance; however, the attentional demand inherent to virtual reality (VR)-based exercise is not well understood. We used a dual-task paradigm to compare the attentional demands of VR-based and non-VR-based (conventional, real-world) exercise: 22 non-disabled older adults performed a primary reaching task to virtual and real targets in a counterbalanced block order while verbally responding to an unanticipated auditory tone in one third of the trials. The attentional demand of the primary reaching task was inferred from the voice response time (VRT) to the auditory tone. Participants' engagement level and task experience were also obtained using questionnaires. The virtual target condition was more attention demanding (significantly longer VRT) than the real target condition. Secondary analyses revealed a significant interaction between engagement level and target condition on attentional demand. For participants who were highly engaged, attentional demand was high and independent of target condition. However, for those who were less engaged, attentional demand was low and depended on target condition (i.e., virtual > real). These findings add important knowledge to the growing body of research pertaining to the development and application of technology-enhanced exercise for elders and for rehabilitation purposes.

Attentional Demand of a Virtual Reality-Based Reaching Task in Nondisabled Older Adults

PubMed Central

Chen, Yi-An; Chung, Yu-Chen; Proffitt, Rachel; Wade, Eric; Winstein, Carolee

2015-01-01

Attention during exercise is known to affect performance; however, the attentional demand inherent to virtual reality (VR)-based exercise is not well understood. We used a dual-task paradigm to compare the attentional demands of VR-based and non-VR-based (conventional, real-world) exercise: 22 non-disabled older adults performed a primary reaching task to virtual and real targets in a counterbalanced block order while verbally responding to an unanticipated auditory tone in one third of the trials. The attentional demand of the primary reaching task was inferred from the voice response time (VRT) to the auditory tone. Participants' engagement level and task experience were also obtained using questionnaires. The virtual target condition was more attention demanding (significantly longer VRT) than the real target condition. Secondary analyses revealed a significant interaction between engagement level and target condition on attentional demand. For participants who were highly engaged, attentional demand was high and independent of target condition. However, for those who were less engaged, attentional demand was low and depended on target condition (i.e., virtual > real). These findings add important knowledge to the growing body of research pertaining to the development and application of technology-enhanced exercise for elders and for rehabilitation purposes. PMID:27004233

Implementation of a Proposed System for Automated Microcode Generation.

DTIC Science & Technology

1984-12-01

Marcia Elaine Provance 6 . PERFORMING ORGANIZATION NAME AND ADDRESS t0. PROGRAM ELEMENT, PROJECT, TASK AREA 6 WORK UNIT NUMBERS * Naval Postgraduate...The proposed microprogramming system is organized around a series of menus which are presented to a microprograrmuer so that she can build FDC 1473... organization is not affected. A computer can also respond more easily to new performance demands and problem solutions. A richer or a larger instruction set

Cyber-workstation for computational neuroscience.

PubMed

Digiovanna, Jack; Rattanatamrong, Prapaporn; Zhao, Ming; Mahmoudi, Babak; Hermer, Linda; Figueiredo, Renato; Principe, Jose C; Fortes, Jose; Sanchez, Justin C

2010-01-01

A Cyber-Workstation (CW) to study in vivo, real-time interactions between computational models and large-scale brain subsystems during behavioral experiments has been designed and implemented. The design philosophy seeks to directly link the in vivo neurophysiology laboratory with scalable computing resources to enable more sophisticated computational neuroscience investigation. The architecture designed here allows scientists to develop new models and integrate them with existing models (e.g. recursive least-squares regressor) by specifying appropriate connections in a block-diagram. Then, adaptive middleware transparently implements these user specifications using the full power of remote grid-computing hardware. In effect, the middleware deploys an on-demand and flexible neuroscience research test-bed to provide the neurophysiology laboratory extensive computational power from an outside source. The CW consolidates distributed software and hardware resources to support time-critical and/or resource-demanding computing during data collection from behaving animals. This power and flexibility is important as experimental and theoretical neuroscience evolves based on insights gained from data-intensive experiments, new technologies and engineering methodologies. This paper describes briefly the computational infrastructure and its most relevant components. Each component is discussed within a systematic process of setting up an in vivo, neuroscience experiment. Furthermore, a co-adaptive brain machine interface is implemented on the CW to illustrate how this integrated computational and experimental platform can be used to study systems neurophysiology and learning in a behavior task. We believe this implementation is also the first remote execution and adaptation of a brain-machine interface.

Cyber-Workstation for Computational Neuroscience

PubMed Central

DiGiovanna, Jack; Rattanatamrong, Prapaporn; Zhao, Ming; Mahmoudi, Babak; Hermer, Linda; Figueiredo, Renato; Principe, Jose C.; Fortes, Jose; Sanchez, Justin C.

2009-01-01

A Cyber-Workstation (CW) to study in vivo, real-time interactions between computational models and large-scale brain subsystems during behavioral experiments has been designed and implemented. The design philosophy seeks to directly link the in vivo neurophysiology laboratory with scalable computing resources to enable more sophisticated computational neuroscience investigation. The architecture designed here allows scientists to develop new models and integrate them with existing models (e.g. recursive least-squares regressor) by specifying appropriate connections in a block-diagram. Then, adaptive middleware transparently implements these user specifications using the full power of remote grid-computing hardware. In effect, the middleware deploys an on-demand and flexible neuroscience research test-bed to provide the neurophysiology laboratory extensive computational power from an outside source. The CW consolidates distributed software and hardware resources to support time-critical and/or resource-demanding computing during data collection from behaving animals. This power and flexibility is important as experimental and theoretical neuroscience evolves based on insights gained from data-intensive experiments, new technologies and engineering methodologies. This paper describes briefly the computational infrastructure and its most relevant components. Each component is discussed within a systematic process of setting up an in vivo, neuroscience experiment. Furthermore, a co-adaptive brain machine interface is implemented on the CW to illustrate how this integrated computational and experimental platform can be used to study systems neurophysiology and learning in a behavior task. We believe this implementation is also the first remote execution and adaptation of a brain-machine interface. PMID:20126436

Assessing the Utility of a Demand Assessment for Functional Analysis

ERIC Educational Resources Information Center

Roscoe, Eileen M.; Rooker, Griffin W.; Pence, Sacha T.; Longworth, Lynlea J.

2009-01-01

We evaluated the utility of an assessment for identifying tasks for the functional analysis demand condition with 4 individuals who had been diagnosed with autism. During the demand assessment, a therapist presented a variety of tasks, and observers measured problem behavior and compliance to identify demands associated with low levels of…

Promoting the experimental dialogue between working memory and chunking: Behavioral data and simulation.

PubMed

Portrat, Sophie; Guida, Alessandro; Phénix, Thierry; Lemaire, Benoît

2016-04-01

Working memory (WM) is a cognitive system allowing short-term maintenance and processing of information. Maintaining information in WM consists, classically, in rehearsing or refreshing it. Chunking could also be considered as a maintenance mechanism. However, in the literature, it is more often used to explain performance than explicitly investigated within WM paradigms. Hence, the aim of the present paper was (1) to strengthen the experimental dialogue between WM and chunking, by studying the effect of acronyms in a computer-paced complex span task paradigm and (2) to formalize explicitly this dialogue within a computational model. Young adults performed a WM complex span task in which they had to maintain series of 7 letters for further recall while performing a concurrent location judgment task. The series to be remembered were either random strings of letters or strings containing a 3-letter acronym that appeared in position 1, 3, or 5 in the series. Together, the data and simulations provide a better understanding of the maintenance mechanisms taking place in WM and its interplay with long-term memory. Indeed, the behavioral WM performance lends evidence to the functional characteristics of chunking that seems to be, especially in a WM complex span task, an attentional time-based mechanism that certainly enhances WM performance but also competes with other processes at hand in WM. Computational simulations support and delineate such a conception by showing that searching for a chunk in long-term memory involves attentionally demanding subprocesses that essentially take place during the encoding phases of the task.

Exploring the Impact of Target Eccentricity and Task Difficulty on Covert Visual Spatial Attention and Its Implications for Brain Computer Interfacing

PubMed Central

Roijendijk, Linsey; Farquhar, Jason; van Gerven, Marcel; Jensen, Ole; Gielen, Stan

2013-01-01

Objective Covert visual spatial attention is a relatively new task used in brain computer interfaces (BCIs) and little is known about the characteristics which may affect performance in BCI tasks. We investigated whether eccentricity and task difficulty affect alpha lateralization and BCI performance. Approach We conducted a magnetoencephalography study with 14 participants who performed a covert orientation discrimination task at an easy or difficult stimulus contrast at either a near (3.5°) or far (7°) eccentricity. Task difficulty was manipulated block wise and subjects were aware of the difficulty level of each block. Main Results Grand average analyses revealed a significantly larger hemispheric lateralization of posterior alpha power in the difficult condition than in the easy condition, while surprisingly no difference was found for eccentricity. The difference between task difficulty levels was significant in the interval between 1.85 s and 2.25 s after cue onset and originated from a stronger decrease in the contralateral hemisphere. No significant effect of eccentricity was found. Additionally, single-trial classification analysis revealed a higher classification rate in the difficult (65.9%) than in the easy task condition (61.1%). No effect of eccentricity was found in classification rate. Significance Our results indicate that manipulating the difficulty of a task gives rise to variations in alpha lateralization and that using a more difficult task improves covert visual spatial attention BCI performance. The variations in the alpha lateralization could be caused by different factors such as an increased mental effort or a higher visual attentional demand. Further research is necessary to discriminate between them. We did not discover any effect of eccentricity in contrast to results of previous research. PMID:24312477

Exploring the impact of target eccentricity and task difficulty on covert visual spatial attention and its implications for brain computer interfacing.

PubMed

Roijendijk, Linsey; Farquhar, Jason; van Gerven, Marcel; Jensen, Ole; Gielen, Stan

2013-01-01

Covert visual spatial attention is a relatively new task used in brain computer interfaces (BCIs) and little is known about the characteristics which may affect performance in BCI tasks. We investigated whether eccentricity and task difficulty affect alpha lateralization and BCI performance. We conducted a magnetoencephalography study with 14 participants who performed a covert orientation discrimination task at an easy or difficult stimulus contrast at either a near (3.5°) or far (7°) eccentricity. Task difficulty was manipulated block wise and subjects were aware of the difficulty level of each block. Grand average analyses revealed a significantly larger hemispheric lateralization of posterior alpha power in the difficult condition than in the easy condition, while surprisingly no difference was found for eccentricity. The difference between task difficulty levels was significant in the interval between 1.85 s and 2.25 s after cue onset and originated from a stronger decrease in the contralateral hemisphere. No significant effect of eccentricity was found. Additionally, single-trial classification analysis revealed a higher classification rate in the difficult (65.9%) than in the easy task condition (61.1%). No effect of eccentricity was found in classification rate. Our results indicate that manipulating the difficulty of a task gives rise to variations in alpha lateralization and that using a more difficult task improves covert visual spatial attention BCI performance. The variations in the alpha lateralization could be caused by different factors such as an increased mental effort or a higher visual attentional demand. Further research is necessary to discriminate between them. We did not discover any effect of eccentricity in contrast to results of previous research.

The effect of task demand and incentive on neurophysiological and cardiovascular markers of effort.

PubMed

Fairclough, Stephen H; Ewing, Kate

2017-09-01

According to motivational intensity theory, effort is proportional to the level of task demand provided that success is possible and successful performance is deemed worthwhile. The current study represents a simultaneous manipulation of demand (working memory load) and success importance (financial incentive) to investigate neurophysiological (EEG) and cardiovascular measures of effort. A 2×2 repeated-measures study was conducted where 18 participants performed a n-back task under three conditions of demand: easy (1-back), hard (4-back) and very hard (7-back). In addition, participants performed these tasks in the presence of performance-contingent financial incentive or in a no-incentive (pilot trial) condition. Three bands of EEG activity were quantified: theta (4-7Hz), lower-alpha (7.5-10Hz) and upper-alpha (10.5-13Hz). Fronto-medial activity in the theta band and activity in the upper-alpha band at frontal, central and parietal sites were sensitive to demand and indicated greatest effort when the task was challenging and success was possible. Mean systolic blood pressure and activity in the lower-alpha band at parietal sites were also sensitive to demand but also increased in the incentive condition across all levels of task demand. The results of the study largely support the predictions of motivational intensity using neurophysiological markers of effort. Copyright © 2017. Published by Elsevier B.V.

The Influence of Load and Speed on Individuals' Movement Behavior.

PubMed

Frost, David M; Beach, Tyson A C; Callaghan, Jack P; McGill, Stuart M

2015-09-01

Because individuals' movement patterns have been linked to their risk of future injury, movement evaluations have become a topic of interest. However, if individuals adapt their movement behavior in response to the demands of a task, the utility of evaluations comprising only low-demand activities could have limited application with regard to the prediction of future injury. This investigation examined the impact of load and speed on individuals' movement behavior. Fifty-two firefighters performed 5 low-demand (i.e., light load, low movement speed) whole-body tasks (i.e., lift, squat, lunge, push, and pull). Each task was then modified by increasing the speed, external load, or speed and load. Select measures of motion were used to characterize the performance of each task, and comparisons were made between conditions. The participants adapted their movement behavior in response to the external demands of a task (64 and 70% of all the variables were influenced [p ≤ 0.05] by changing the load and speed, respectively), but in a manner unique to the task and type of demand. The participants exhibited greater spine and frontal plane knee motion in response to an increase in speed when compared with increasing loads. However, there were a large number of movement strategies exhibited by individual firefighters that differed from the group's response. The data obtained here imply that individuals may not be physically prepared to perform safely or effectively when a task's demands are elevated simply because they exhibit the ability to perform a low-demand activity with competence. Therefore, movement screens comprising only low-demand activities may not adequately reflect an individual's capacity, or their risk of injury, and could adversely affect any recommendations that are made for training or job performance.

Reading Text While Driving

PubMed Central

Horrey, William J.; Hoffman, Joshua D.

2015-01-01

Objective In this study, we investigated how drivers adapt secondary-task initiation and time-sharing behavior when faced with fluctuating driving demands. Background Reading text while driving is particularly detrimental; however, in real-world driving, drivers actively decide when to perform the task. Method In a test track experiment, participants were free to decide when to read messages while driving along a straight road consisting of an area with increased driving demands (demand zone) followed by an area with low demands. A message was made available shortly before the vehicle entered the demand zone. We manipulated the type of driving demands (baseline, narrow lane, pace clock, combined), message format (no message, paragraph, parsed), and the distance from the demand zone when the message was available (near, far). Results In all conditions, drivers started reading messages (drivers’ first glance to the display) before entering or before leaving the demand zone but tended to wait longer when faced with increased driving demands. While reading messages, drivers looked more or less off road, depending on types of driving demands. Conclusions For task initiation, drivers avoid transitions from low to high demands; however, they are not discouraged when driving demands are already elevated. Drivers adjust time-sharing behavior according to driving demands while performing secondary tasks. Nonetheless, such adjustment may be less effective when total demands are high. Application This study helps us to understand a driver’s role as an active controller in the context of distracted driving and provides insights for developing distraction interventions. PMID:25850162

HAL/SM language specification. [programming languages and computer programming for space shuttles

NASA Technical Reports Server (NTRS)

Williams, G. P. W., Jr.; Ross, C.

1975-01-01

A programming language is presented for the flight software of the NASA Space Shuttle program. It is intended to satisfy virtually all of the flight software requirements of the space shuttle. To achieve this, it incorporates a wide range of features, including applications-oriented data types and organizations, real time control mechanisms, and constructs for systems programming tasks. It is a higher order language designed to allow programmers, analysts, and engineers to communicate with the computer in a form approximating natural mathematical expression. Parts of the English language are combined with standard notation to provide a tool that readily encourages programming without demanding computer hardware expertise. Block diagrams and flow charts are included. The semantics of the language is discussed.

A FPGA-based architecture for real-time image matching

NASA Astrophysics Data System (ADS)

Wang, Jianhui; Zhong, Sheng; Xu, Wenhui; Zhang, Weijun; Cao, Zhiguo

2013-10-01

Image matching is a fundamental task in computer vision. It is used to establish correspondence between two images taken at different viewpoint or different time from the same scene. However, its large computational complexity has been a challenge to most embedded systems. This paper proposes a single FPGA-based image matching system, which consists of SIFT feature detection, BRIEF descriptor extraction and BRIEF matching. It optimizes the FPGA architecture for the SIFT feature detection to reduce the FPGA resources utilization. Moreover, we implement BRIEF description and matching on FPGA also. The proposed system can implement image matching at 30fps (frame per second) for 1280x720 images. Its processing speed can meet the demand of most real-life computer vision applications.

Effects of task demands on the early neural processing of fearful and happy facial expressions

PubMed Central

Itier, Roxane J.; Neath-Tavares, Karly N.

2017-01-01

Task demands shape how we process environmental stimuli but their impact on the early neural processing of facial expressions remains unclear. In a within-subject design, ERPs were recorded to the same fearful, happy and neutral facial expressions presented during a gender discrimination, an explicit emotion discrimination and an oddball detection tasks, the most studied tasks in the field. Using an eye tracker, fixation on the face nose was enforced using a gaze-contingent presentation. Task demands modulated amplitudes from 200–350ms at occipito-temporal sites spanning the EPN component. Amplitudes were more negative for fearful than neutral expressions starting on N170 from 150–350ms, with a temporo-occipital distribution, whereas no clear effect of happy expressions was seen. Task and emotion effects never interacted in any time window or for the ERP components analyzed (P1, N170, EPN). Thus, whether emotion is explicitly discriminated or irrelevant for the task at hand, neural correlates of fearful and happy facial expressions seem immune to these task demands during the first 350ms of visual processing. PMID:28315309

What's the Problem? Familiarity Working Memory, and Transfer in a Problem-Solving Task.

PubMed

Kole, James A; Snyder, Hannah R; Brojde, Chandra L; Friend, Angela

2015-01-01

The contributions of familiarity and working memory to transfer were examined in the Tower of Hanoi task. Participants completed 3 different versions of the task: a standard 3-disk version, a clothing exchange task that included familiar semantic content, and a tea ceremony task that included unfamiliar semantic content. The constraints on moves were equivalent across tasks, and each could be solved with the same sequence of movements. Working memory demands were manipulated by the provision of a (static or dynamic) visual representation of the problem. Performance was equivalent for the standard Tower of Hanoi and clothing exchange tasks but worse for the tea ceremony task, and it decreased with increasing working memory demands. Furthermore, the standard Tower of Hanoi task and clothing exchange tasks independently, additively, and equivalently transferred to subsequent tasks, whereas the tea ceremony task did not. The results suggest that both familiarity and working memory demands determine overall level of performance, whereas familiarity influences transfer.

Assessing the Cognitive Demands of a Century of Reading Curricula: An Analysis of Reading Text and Comprehension Tasks from 1910 to 2000

ERIC Educational Resources Information Center

Stevens, Robert J.; Lu, Xiaofei; Baker, David P.; Ray, Melissa N.; Eckert, Sarah A.; Gamson, David A.

2015-01-01

This research investigated the cognitive demands of reading curricula from 1910 to 2000. We considered both the nature of the text used and the comprehension tasks asked of students in determining the cognitive demands of the curricula. Contrary to the common assumption of a trend of simplification of the texts and comprehension tasks in third-…

A fast discrete S-transform for biomedical signal processing.

PubMed

Brown, Robert A; Frayne, Richard

2008-01-01

Determining the frequency content of a signal is a basic operation in signal and image processing. The S-transform provides both the true frequency and globally referenced phase measurements characteristic of the Fourier transform and also generates local spectra, as does the wavelet transform. Due to this combination, the S-transform has been successfully demonstrated in a variety of biomedical signal and image processing tasks. However, the computational demands of the S-transform have limited its application in medicine to this point in time. This abstract introduces the fast S-transform, a more efficient discrete implementation of the classic S-transform with dramatically reduced computational requirements.

Human behavior and human performance: Psychomotor demands

NASA Technical Reports Server (NTRS)

1992-01-01

The results of several experiments are presented in abstract form. These studies are critical for the interpretation and acceptance of flight based science to be conducted by the Behavior and Performance project. Some representative titles are as follow: External audio for IBM/PC compatible computers; A comparative assessment of psychomotor performance (target prediction by humans and macaques); Response path (a dependent measure for computer maze solving and other tasks); Behavioral asymmetries of psychomotor performance in Rhesus monkey (a dissociation between hand preference and skill); Testing primates with joystick based automated apparatus; and Environmental enrichment and performance assessment for ground or flight based research with primates;

Knowledge acquisition and interface design for learning on demand systems

NASA Technical Reports Server (NTRS)

Nelson, Wayne A.

1993-01-01

The rapid changes in our world precipitated by technology have created new problems and new challenges for education and training. A knowledge 'explosion' is occurring as our society moves toward a service oriented economy that relies on information as the major resource. Complex computer systems are beginning to dominate the workplace, causing alarming growth and change in many fields. The rapidly changing nature of the workplace, especially in fields related to information technology, requires that our knowledge be updated constantly. This characteristic of modern society poses seemingly unsolvable instructional problems involving coverage and obsolescence. The sheer amount of information to be learned is rapidly increasing, while at the same time some information becomes obsolete in light of new information. Education, therefore, must become a lifelong process that features learning of new material and skills as needed in relation to the job to be done. Because of the problems cited above, the current model of learning in advance may no longer be feasible in our high-technology world. In many cases, learning in advance is impossible because there are simply too many things to learn. In addition, learning in advance can be time consuming, and often results in decontextualized knowledge that does not readily transfer to the work environment. The large and growing discrepancy between the amount of potentially relevant knowledge available and the amount a person can know and remember makes learning on demand an important alternative to current instructional practices. Learning on demand takes place whenever an individual must learn something new in order to perform a task or make a decision. Learning on demand is a promising approach for addressing the problems of coverage and obsolescence because learning is contextualized and integrated into the task environment rather than being relegated to a separate phase that precedes work. Learning on demand allows learners to see for themselves the usefulness of new knowledge for actual problem situations, thereby increasing the motivation for learning new information. Finally, learning on demand makes new information relevant to the task at hand, leading to more informed decision making, better quality products, and improved performance.

Task parameters affecting ergonomic demands and productivity of HVAC duct installation.

PubMed

Mitropoulos, Panagiotis; Hussain, Sanaa; Guarascio-Howard, Linda; Memarian, Babak

2014-01-01

Mechanical installation workers experience work-related musculoskeletal disorders (WMSDs) at high rates. (1) Quantify the ergonomic demands during HVAC installation, (2) identify the tasks and task parameters that generated extreme ergonomic demands, and (3) propose improvements to reduce the WMSDs among mechanical workers. The study focused on installation of rectangular ductwork components using ladders, and analyzed five operations by two mechanical contractors. Using continuous time observational assessment, the videotaped operations were analyzed along two dimensions: (1) the production tasks and durations, and (2) the ergonomic demands for four body regions (neck, arms/shoulders, back, and knees). The analysis identified tasks with low portion of productive time and high portion of extreme postures, and task parameters that generated extreme postures. Duct alignment was the task with the highest portion of extreme postures. The position of the ladder (angle and distance from the duct) was a task parameter that strongly influenced the extreme postures for back, neck and shoulders. Other contributing factors included the difficulty to reach the hand tools when working on the ladder, the congestion of components in the ceiling, and the space between the duct and the ceiling. The identified tasks and factors provide directions for improvement.

Quantitative work demands, emotional demands, and cognitive stress symptoms in surgery nurses.

PubMed

Elfering, Achim; Grebner, Simone; Leitner, Monika; Hirschmüller, Anja; Kubosch, Eva Johanna; Baur, Heiner

2017-06-01

In surgery, cognitive stress symptoms, including problems in concentrating, deciding, memorising, and reflecting are risks to patient safety. Recent evidence points to social stressors as antecedents of cognitive stress symptoms in surgery personnel. The current study tests whether cognitive stress symptoms are positively associated with emotional abuse, emotional- and task-related demands and resources in surgery work. Forty-eight surgery nurses from two hospitals filled out the Copenhagen Psychosocial Questionnaire in its German version. Task-related and emotional demands were positively related to cognitive stress symptoms. In a stepwise, multiple, linear regression of cognitive stress symptoms on task-related and emotional demands, emotional abuse and emotional demands were unique predictors (p < .05). Efforts to increase patient safety should address emotional abuse, emotional demands, and, therefore, communication and cooperation team climate in surgery personnel.

Cognitive performance modeling based on general systems performance theory.

PubMed

Kondraske, George V

2010-01-01

General Systems Performance Theory (GSPT) was initially motivated by problems associated with quantifying different aspects of human performance. It has proved to be invaluable for measurement development and understanding quantitative relationships between human subsystem capacities and performance in complex tasks. It is now desired to bring focus to the application of GSPT to modeling of cognitive system performance. Previous studies involving two complex tasks (i.e., driving and performing laparoscopic surgery) and incorporating measures that are clearly related to cognitive performance (information processing speed and short-term memory capacity) were revisited. A GSPT-derived method of task analysis and performance prediction termed Nonlinear Causal Resource Analysis (NCRA) was employed to determine the demand on basic cognitive performance resources required to support different levels of complex task performance. This approach is presented as a means to determine a cognitive workload profile and the subsequent computation of a single number measure of cognitive workload (CW). Computation of CW may be a viable alternative to measuring it. Various possible "more basic" performance resources that contribute to cognitive system performance are discussed. It is concluded from this preliminary exploration that a GSPT-based approach can contribute to defining cognitive performance models that are useful for both individual subjects and specific groups (e.g., military pilots).

Cooperative business management strategies for the U.S. integrated textile complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washington, K.E.

1995-12-31

The mission of the American Textile (AMTEX{trademark}) Partnership is to engage the unique technical resources of the Department of Energy National Laboratories to work with the US Integrated Textile Complex (US ITC) and research universities to develop and deploy technologies that will increase the competitiveness of the US ITC. The objectives of the Demand Activated Manufacturing Architecture (DAMA) project of AMTEX are: (1) to determine strategic business structure changes for the US ITC; (2) to establish a textile industry electronic marketplace, (3) to provide methods for US ITC education ad implementation of an electronic marketplace. The Enterprise Modeling and Simulationmore » Task of DAMA is focusing on the first DAMA goal as described in another paper of this conference. The Cooperative Business Management (CBM) Task of DAMA is developing computer-based tools that will render system-wide information accessible for improved decision making. Three CBM strategies and the associated computer tools being developed to support their implementation are described in this paper. This effort is addressing the second DAMA goal to establish a textile industry electronic marketplace in concert with the Connectivity and Infrastructure Task of DAMA. As the CBM tools mature, they will be commercialized through the DAMA Education, Outreach and Commercialization Task of DAMA to achieve the third and final DAMA goal.« less

Beliefs about willpower moderate the effect of previous day demands on next day’s expectations and effective goal striving

PubMed Central

Bernecker, Katharina; Job, Veronika

2015-01-01

Research suggests that beliefs about willpower affect self-regulation following previous self-regulatory demands (Job et al., 2010). Some people believe that their willpower is limited, meaning that after a demanding task it needs to be replenished (limited theory). By contrast, others believe that willpower is not limited and that previous self-control tasks even activate willpower (non-limited theory). We hypothesized that when people experience a demanding day their beliefs about willpower predict their expected capacity to self-regulate and their actual self-regulation on the following day. In a daily diary study (N = 157), we measured students’ daily level of demands, their expected performance in unpleasant tasks, and their effective goal striving. Results showed that following a demanding day, students with a non-limited theory had higher expectations about their progress in unpleasant tasks and were striving more efficiently for their goals than students with a limited theory. These findings suggest that beliefs about willpower affect whether demands experienced on a previous day have positive or negative consequences on people’s self-regulation. PMID:26528198

Exploring the Cognitive Demand and Features of Problem Solving Tasks in Primary Mathematics Classrooms

ERIC Educational Resources Information Center

McCormick, Melody

2016-01-01

Student learning is greatest in classrooms where students engage in problem solving tasks that are cognitively demanding. However, there are growing concerns that many Australian students are given limited opportunities to engage in these types of tasks. 108 upper primary school teachers were surveyed to examine task features and cognitive demand…

Processing Demands Impact 3-Year-Olds' Performance in a Spontaneous-Response Task: New Evidence for the Processing-Load Account of Early False-Belief Understanding.

PubMed

Scott, Rose M; Roby, Erin

2015-01-01

Prior to age four, children succeed in non-elicited-response false-belief tasks but fail elicited-response false-belief tasks. To explain this discrepancy, the processing-load account argues that the capacity to represent beliefs emerges in infancy, as indicated by early success on non-elicited-response tasks, but that children's ability to demonstrate this capacity depends on the processing demands of the task and children's processing skills. When processing demands exceed young children's processing abilities, such as in standard elicited-response tasks, children fail despite their capacity to represent beliefs. Support for this account comes from recent evidence that reducing processing demands improves young children's performance: when demands are sufficiently reduced, 2.5-year-olds succeed in elicited-response tasks. Here we sought complementary evidence for the processing-load account by examining whether increasing processing demands impeded children's performance in a non-elicited-response task. 3-year-olds were tested in a preferential-looking task in which they heard a change-of-location false-belief story accompanied by a picture book; across children, we manipulated the amount of linguistic ambiguity in the story. The final page of the book showed two images: one that was consistent with the main character's false belief and one that was consistent with reality. When the story was relatively unambiguous, children looked reliably longer at the false-belief-consistent image, successfully demonstrating their false-belief understanding. When the story was ambiguous, however, this undermined children's performance: looking times to the belief-consistent image were correlated with verbal ability, and only children with verbal skills in the upper quartile of the sample demonstrated a significant preference for the belief-consistent image. These results support the processing-load account by demonstrating that regardless of whether a task involves an elicited response, children's performance depends on the processing demands of the task and their processing skills. These findings also have implications for alternative, deflationary accounts of early false-belief understanding.

Processing Demands Impact 3-Year-Olds’ Performance in a Spontaneous-Response Task: New Evidence for the Processing-Load Account of Early False-Belief Understanding

PubMed Central

Scott, Rose M.; Roby, Erin

2015-01-01

Prior to age four, children succeed in non-elicited-response false-belief tasks but fail elicited-response false-belief tasks. To explain this discrepancy, the processing-load account argues that the capacity to represent beliefs emerges in infancy, as indicated by early success on non-elicited-response tasks, but that children’s ability to demonstrate this capacity depends on the processing demands of the task and children’s processing skills. When processing demands exceed young children’s processing abilities, such as in standard elicited-response tasks, children fail despite their capacity to represent beliefs. Support for this account comes from recent evidence that reducing processing demands improves young children’s performance: when demands are sufficiently reduced, 2.5-year-olds succeed in elicited-response tasks. Here we sought complementary evidence for the processing-load account by examining whether increasing processing demands impeded children’s performance in a non-elicited-response task. 3-year-olds were tested in a preferential-looking task in which they heard a change-of-location false-belief story accompanied by a picture book; across children, we manipulated the amount of linguistic ambiguity in the story. The final page of the book showed two images: one that was consistent with the main character’s false belief and one that was consistent with reality. When the story was relatively unambiguous, children looked reliably longer at the false-belief-consistent image, successfully demonstrating their false-belief understanding. When the story was ambiguous, however, this undermined children’s performance: looking times to the belief-consistent image were correlated with verbal ability, and only children with verbal skills in the upper quartile of the sample demonstrated a significant preference for the belief-consistent image. These results support the processing-load account by demonstrating that regardless of whether a task involves an elicited response, children’s performance depends on the processing demands of the task and their processing skills. These findings also have implications for alternative, deflationary accounts of early false-belief understanding. PMID:26562840

The association of subjective workload dimensions on quality of care and pharmacist quality of work life.

PubMed

Chui, Michelle A; Look, Kevin A; Mott, David A

2014-01-01

Workload has been described both objectively (e.g., number of prescriptions dispensed per pharmacist) as well as subjectively (e.g., pharmacist's perception of busyness). These approaches might be missing important characteristics of pharmacist workload that have not been previously identified and measured. To measure the association of community pharmacists' workload perceptions at three levels (organization, job, and task) with job satisfaction, burnout, and perceived performance of two tasks in the medication dispensing process. A secondary data analysis was performed using cross-sectional survey data collected from Wisconsin (US) community pharmacists. Organization-related workload was measured as staffing adequacy; job-related workload was measured as general and specific job demands; task-related workload was measured as internal and external mental demands. Pharmacists' perceived task performance was assessed for patient profile review and patient consultation. The survey was administered to a random sample of 500 pharmacists who were asked to opt in if they were a community pharmacist. Descriptive statistics and correlations of study variables were determined. Two structural equation models were estimated to examine relationships between the study variables and perceived task performance. From the 224 eligible community pharmacists that agreed to participate, 165 (73.7%) usable surveys were completed and returned. Job satisfaction and job-related monitoring demands had direct positive associations with both dispensing tasks. External task demands were negatively related to perceived patient consultation performance. Indirect effects on both tasks were primarily mediated through job satisfaction, which was positively related to staffing adequacy and cognitive job demands and negatively related to volume job demands. External task demands had an additional indirect effect on perceived patient consultation performance, as it was associated with lower levels of job satisfaction and higher levels of burnout. Allowing community pharmacists to concentrate on tasks and limiting interruptions while performing these tasks are important factors in improving quality of patient care and pharmacist work life. The results have implications for strategies to improve patient safety and pharmacist performance. Copyright © 2014 Elsevier Inc. All rights reserved.

The Association of Subjective Workload Dimensions on Quality of Care and Pharmacist Quality of Work Life

PubMed Central

Chui, Michelle A.; Look, Kevin A.; Mott, David A.

2013-01-01

Background Workload has been described both objectively (e.g., number of prescriptions dispensed per pharmacist) as well as subjectively (e.g., pharmacist’s perception of busyness). These approaches might be missing important characteristics of pharmacist workload that have not been previously identified and measured. Objectives To measure the association of community pharmacists’ workload perceptions at three levels (organization, job, and task) with job satisfaction, burnout, and perceived performance of two tasks in the medication dispensing process. Methods A secondary data analysis was performed using cross-sectional survey data collected from Wisconsin (US) community pharmacists. Organization–related workload was measured as staffing adequacy; job-related workload was measured as general and specific job demands; task-related workload was measured as internal and external mental demands. Pharmacists’ perceived task performance was assessed for patient profile review and patient consultation. The survey was administered to a random sample of 500 pharmacists who were asked to opt in if they were a community pharmacist. Descriptive statistics and correlations of study variables were determined. Two structural equation models were estimated to examine relationships between the study variables and perceived task performance. Results From the 224 eligible community pharmacists that agreed to participate, 165 (73.7%) usable surveys were completed and returned. Job satisfaction and job-related monitoring demands had direct positive associations with both dispensing tasks. External task demands were negatively related to perceived patient consultation performance. Indirect effects on both tasks were primarily mediated through job satisfaction, which was positively related to staffing adequacy and cognitive job demands and negatively related to volume job demands. External task demands had an additional indirect effect on perceived patient consultation performance, as it was associated with lower levels of job satisfaction and higher levels of burnout. Implications/Conclusions Allowing community pharmacists to concentrate on tasks and limiting interruptions while performing these tasks are important factors in improving quality of patient care and pharmacist work life. The results have implications for strategies to improve patient safety and pharmacist performance. PMID:23791360

Heart rate variability and cognitive processing: The autonomic response to task demands.

PubMed

Luque-Casado, Antonio; Perales, José C; Cárdenas, David; Sanabria, Daniel

2016-01-01

This study investigated variations in heart rate variability (HRV) as a function of cognitive demands. Participants completed an execution condition including the psychomotor vigilance task, a working memory task and a duration discrimination task. The control condition consisted of oddball versions (participants had to detect the rare event) of the tasks from the execution condition, designed to control for the effect of the task parameters (stimulus duration and stimulus rate) on HRV. The NASA-TLX questionnaire was used as a subjective measure of cognitive workload across tasks and conditions. Three major findings emerged from this study. First, HRV varied as a function of task demands (with the lowest values in the working memory task). Second, and crucially, we found similar HRV values when comparing each of the tasks with its oddball control equivalent, and a significant decrement in HRV as a function of time-on-task. Finally, the NASA-TLX results showed larger cognitive workload in the execution condition than in the oddball control condition, and scores variations as a function of task. Taken together, our results suggest that HRV is highly sensitive to overall demands of sustained attention over and above the influence of other cognitive processes suggested by previous literature. In addition, our study highlights a potential dissociation between objective and subjective measures of mental workload, with important implications in applied settings. Copyright © 2015 Elsevier B.V. All rights reserved.

The curse of planning: dissecting multiple reinforcement-learning systems by taxing the central executive.

PubMed

Otto, A Ross; Gershman, Samuel J; Markman, Arthur B; Daw, Nathaniel D

2013-05-01

A number of accounts of human and animal behavior posit the operation of parallel and competing valuation systems in the control of choice behavior. In these accounts, a flexible but computationally expensive model-based reinforcement-learning system has been contrasted with a less flexible but more efficient model-free reinforcement-learning system. The factors governing which system controls behavior-and under what circumstances-are still unclear. Following the hypothesis that model-based reinforcement learning requires cognitive resources, we demonstrated that having human decision makers perform a demanding secondary task engenders increased reliance on a model-free reinforcement-learning strategy. Further, we showed that, across trials, people negotiate the trade-off between the two systems dynamically as a function of concurrent executive-function demands, and people's choice latencies reflect the computational expenses of the strategy they employ. These results demonstrate that competition between multiple learning systems can be controlled on a trial-by-trial basis by modulating the availability of cognitive resources.

The Curse of Planning: Dissecting multiple reinforcement learning systems by taxing the central executive

PubMed Central

Otto, A. Ross; Gershman, Samuel J.; Markman, Arthur B.; Daw, Nathaniel D.

2013-01-01

A number of accounts of human and animal behavior posit the operation of parallel and competing valuation systems in the control of choice behavior. Along these lines, a flexible but computationally expensive model-based reinforcement learning system has been contrasted with a less flexible but more efficient model-free reinforcement learning system. The factors governing which system controls behavior—and under what circumstances—are still unclear. Based on the hypothesis that model-based reinforcement learning requires cognitive resources, we demonstrate that having human decision-makers perform a demanding secondary task engenders increased reliance on a model-free reinforcement learning strategy. Further, we show that across trials, people negotiate this tradeoff dynamically as a function of concurrent executive function demands and their choice latencies reflect the computational expenses of the strategy employed. These results demonstrate that competition between multiple learning systems can be controlled on a trial-by-trial basis by modulating the availability of cognitive resources. PMID:23558545

How Auditory Experience Differentially Influences the Function of Left and Right Superior Temporal Cortices.

PubMed

Twomey, Tae; Waters, Dafydd; Price, Cathy J; Evans, Samuel; MacSweeney, Mairéad

2017-09-27

To investigate how hearing status, sign language experience, and task demands influence functional responses in the human superior temporal cortices (STC) we collected fMRI data from deaf and hearing participants (male and female), who either acquired sign language early or late in life. Our stimuli in all tasks were pictures of objects. We varied the linguistic and visuospatial processing demands in three different tasks that involved decisions about (1) the sublexical (phonological) structure of the British Sign Language (BSL) signs for the objects, (2) the semantic category of the objects, and (3) the physical features of the objects.Neuroimaging data revealed that in participants who were deaf from birth, STC showed increased activation during visual processing tasks. Importantly, this differed across hemispheres. Right STC was consistently activated regardless of the task whereas left STC was sensitive to task demands. Significant activation was detected in the left STC only for the BSL phonological task. This task, we argue, placed greater demands on visuospatial processing than the other two tasks. In hearing signers, enhanced activation was absent in both left and right STC during all three tasks. Lateralization analyses demonstrated that the effect of deafness was more task-dependent in the left than the right STC whereas it was more task-independent in the right than the left STC. These findings indicate how the absence of auditory input from birth leads to dissociable and altered functions of left and right STC in deaf participants. SIGNIFICANCE STATEMENT Those born deaf can offer unique insights into neuroplasticity, in particular in regions of superior temporal cortex (STC) that primarily respond to auditory input in hearing people. Here we demonstrate that in those deaf from birth the left and the right STC have altered and dissociable functions. The right STC was activated regardless of demands on visual processing. In contrast, the left STC was sensitive to the demands of visuospatial processing. Furthermore, hearing signers, with the same sign language experience as the deaf participants, did not activate the STCs. Our data advance current understanding of neural plasticity by determining the differential effects that hearing status and task demands can have on left and right STC function. Copyright © 2017 Twomey et al.

Reading text while driving: understanding drivers' strategic and tactical adaptation to distraction.

PubMed

Liang, Yulan; Horrey, William J; Hoffman, Joshua D

2015-03-01

In this study, we investigated how drivers adapt secondary-task initiation and time-sharing behavior when faced with fluctuating driving demands. Reading text while driving is particularly detrimental; however, in real-world driving, drivers actively decide when to perform the task. In a test track experiment, participants were free to decide when to read messages while driving along a straight road consisting of an area with increased driving demands (demand zone) followed by an area with low demands. A message was made available shortly before the vehicle entered the demand zone. We manipulated the type of driving demands (baseline, narrow lane, pace clock, combined), message format (no message, paragraph, parsed), and the distance from the demand zone when the message was available (near, far). In all conditions, drivers started reading messages (drivers' first glance to the display) before entering or before leaving the demand zone but tended to wait longer when faced with increased driving demands. While reading messages, drivers looked more or less off road, depending on types of driving demands. For task initiation, drivers avoid transitions from low to high demands; however, they are not discouraged when driving demands are already elevated. Drivers adjust time-sharing behavior according to driving demands while performing secondary tasks. Nonetheless, such adjustment may be less effective when total demands are high. This study helps us to understand a driver's role as an active controller in the context of distracted driving and provides insights for developing distraction interventions. © 2014, Human Factors and Ergonomics Society.

Dealing with prospective memory demands while performing an ongoing task: Shared processing, increased on-task focus, or both?

PubMed

Rummel, Jan; Smeekens, Bridget A; Kane, Michael J

2017-07-01

Prospective memory (PM) is the cognitive ability to remember to fulfill intended action plans at the appropriate future moment. Current theories assume that PM fulfillment draws on attentional processes. Accordingly, pending PM intentions interfere with other ongoing tasks to the extent to which both tasks rely on the same processes. How do people manage the competition between PM and ongoing-task demands? Based on research relating mind wandering and attentional control (Kane & McVay, 2012), we argue that people may not only change the way they process ongoing-task stimuli when given a PM intention, but they may also engage in less off-task thinking than they otherwise would. That is, people focus more strongly on the tasks at hand and dedicate considerable conscious thought to the PM goal. We tested this hypothesis by asking subjects to periodically report on their thoughts during prototypical PM (and control) tasks. Task-unrelated thought rates dropped when participants performed an ongoing task while holding a PM intention versus performing the ongoing task alone (Experiment 1), even when PM demands were minimized (Experiment 2) and more so when PM execution was especially rewarded (Experiment 3). Our findings suggest that PM demands not only elicit a cost to ongoing-task processing, but they also induce a stronger on-task focus and promote conscious thoughts about the PM intention. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Cross-modal attention influences auditory contrast sensitivity: Decreasing visual load improves auditory thresholds for amplitude- and frequency-modulated sounds.

PubMed

Ciaramitaro, Vivian M; Chow, Hiu Mei; Eglington, Luke G

2017-03-01

We used a cross-modal dual task to examine how changing visual-task demands influenced auditory processing, namely auditory thresholds for amplitude- and frequency-modulated sounds. Observers had to attend to two consecutive intervals of sounds and report which interval contained the auditory stimulus that was modulated in amplitude (Experiment 1) or frequency (Experiment 2). During auditory-stimulus presentation, observers simultaneously attended to a rapid sequential visual presentation-two consecutive intervals of streams of visual letters-and had to report which interval contained a particular color (low load, demanding less attentional resources) or, in separate blocks of trials, which interval contained more of a target letter (high load, demanding more attentional resources). We hypothesized that if attention is a shared resource across vision and audition, an easier visual task should free up more attentional resources for auditory processing on an unrelated task, hence improving auditory thresholds. Auditory detection thresholds were lower-that is, auditory sensitivity was improved-for both amplitude- and frequency-modulated sounds when observers engaged in a less demanding (compared to a more demanding) visual task. In accord with previous work, our findings suggest that visual-task demands can influence the processing of auditory information on an unrelated concurrent task, providing support for shared attentional resources. More importantly, our results suggest that attending to information in a different modality, cross-modal attention, can influence basic auditory contrast sensitivity functions, highlighting potential similarities between basic mechanisms for visual and auditory attention.

The Use Of Computational Human Performance Modeling As Task Analysis Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacuqes Hugo; David Gertman

2012-07-01

During a review of the Advanced Test Reactor safety basis at the Idaho National Laboratory, human factors engineers identified ergonomic and human reliability risks involving the inadvertent exposure of a fuel element to the air during manual fuel movement and inspection in the canal. There were clear indications that these risks increased the probability of human error and possible severe physical outcomes to the operator. In response to this concern, a detailed study was conducted to determine the probability of the inadvertent exposure of a fuel element. Due to practical and safety constraints, the task network analysis technique was employedmore » to study the work procedures at the canal. Discrete-event simulation software was used to model the entire procedure as well as the salient physical attributes of the task environment, such as distances walked, the effect of dropped tools, the effect of hazardous body postures, and physical exertion due to strenuous tool handling. The model also allowed analysis of the effect of cognitive processes such as visual perception demands, auditory information and verbal communication. The model made it possible to obtain reliable predictions of operator performance and workload estimates. It was also found that operator workload as well as the probability of human error in the fuel inspection and transfer task were influenced by the concurrent nature of certain phases of the task and the associated demand on cognitive and physical resources. More importantly, it was possible to determine with reasonable accuracy the stages as well as physical locations in the fuel handling task where operators would be most at risk of losing their balance and falling into the canal. The model also provided sufficient information for a human reliability analysis that indicated that the postulated fuel exposure accident was less than credible.« less

On-demand Simulation of Atmospheric Transport Processes on the AlpEnDAC Cloud

NASA Astrophysics Data System (ADS)

Hachinger, S.; Harsch, C.; Meyer-Arnek, J.; Frank, A.; Heller, H.; Giemsa, E.

2016-12-01

The "Alpine Environmental Data Analysis Centre" (AlpEnDAC) develops a data-analysis platform for high-altitude research facilities within the "Virtual Alpine Observatory" project (VAO). This platform, with its web portal, will support use cases going much beyond data management: On user request, the data are augmented with "on-demand" simulation results, such as air-parcel trajectories for tracing down the source of pollutants when they appear in high concentration. The respective back-end mechanism uses the Compute Cloud of the Leibniz Supercomputing Centre (LRZ) to transparently calculate results requested by the user, as far as they have not yet been stored in AlpEnDAC. The queuing-system operation model common in supercomputing is replaced by a model in which Virtual Machines (VMs) on the cloud are automatically created/destroyed, providing the necessary computing power immediately on demand. From a security point of view, this allows to perform simulations in a sandbox defined by the VM configuration, without direct access to a computing cluster. Within few minutes, the user receives conveniently visualized results. The AlpEnDAC infrastructure is distributed among two participating institutes [front-end at German Aerospace Centre (DLR), simulation back-end at LRZ], requiring an efficient mechanism for synchronization of measured and augmented data. We discuss our iRODS-based solution for these data-management tasks as well as the general AlpEnDAC framework. Our cloud-based offerings aim at making scientific computing for our users much more convenient and flexible than it has been, and to allow scientists without a broad background in scientific computing to benefit from complex numerical simulations.

State-based versus reward-based motivation in younger and older adults.

PubMed

Worthy, Darrell A; Cooper, Jessica A; Byrne, Kaileigh A; Gorlick, Marissa A; Maddox, W Todd

2014-12-01

Recent decision-making work has focused on a distinction between a habitual, model-free neural system that is motivated toward actions that lead directly to reward and a more computationally demanding goal-directed, model-based system that is motivated toward actions that improve one's future state. In this article, we examine how aging affects motivation toward reward-based versus state-based decision making. Participants performed tasks in which one type of option provided larger immediate rewards but the alternative type of option led to larger rewards on future trials, or improvements in state. We predicted that older adults would show a reduced preference for choices that led to improvements in state and a greater preference for choices that maximized immediate reward. We also predicted that fits from a hybrid reinforcement-learning model would indicate greater model-based strategy use in younger than in older adults. In line with these predictions, older adults selected the options that maximized reward more often than did younger adults in three of the four tasks, and modeling results suggested reduced model-based strategy use. In the task where older adults showed similar behavior to younger adults, our model-fitting results suggested that this was due to the utilization of a win-stay-lose-shift heuristic rather than a more complex model-based strategy. Additionally, within older adults, we found that model-based strategy use was positively correlated with memory measures from our neuropsychological test battery. We suggest that this shift from state-based to reward-based motivation may be due to age related declines in the neural structures needed for more computationally demanding model-based decision making.

Effects of task demands on the early neural processing of fearful and happy facial expressions.

PubMed

Itier, Roxane J; Neath-Tavares, Karly N

2017-05-15

Task demands shape how we process environmental stimuli but their impact on the early neural processing of facial expressions remains unclear. In a within-subject design, ERPs were recorded to the same fearful, happy and neutral facial expressions presented during a gender discrimination, an explicit emotion discrimination and an oddball detection tasks, the most studied tasks in the field. Using an eye tracker, fixation on the face nose was enforced using a gaze-contingent presentation. Task demands modulated amplitudes from 200 to 350ms at occipito-temporal sites spanning the EPN component. Amplitudes were more negative for fearful than neutral expressions starting on N170 from 150 to 350ms, with a temporo-occipital distribution, whereas no clear effect of happy expressions was seen. Task and emotion effects never interacted in any time window or for the ERP components analyzed (P1, N170, EPN). Thus, whether emotion is explicitly discriminated or irrelevant for the task at hand, neural correlates of fearful and happy facial expressions seem immune to these task demands during the first 350ms of visual processing. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of equalizing landing task demands on sex differences in lower extremity energy absorption.

PubMed

Montgomery, Melissa M; Shultz, Sandra J; Schmitz, Randy J

2014-08-01

Less lean mass and strength may result in greater relative task demands on females compared to males when landing from a standardized height and could explain sex differences in energy absorption strategies. We compared the magnitude of sex differences in energy absorption when task demands were equalized relative to the amount of lower extremity lean mass available to dissipate kinetic energy upon landing. Male-female pairs (n=35) were assessed for lower extremity lean mass with dual-energy X-ray absorptiometry. Relative task demands were calculated when landing from a standardized height. Based on the difference in lower extremity lean mass within each pair, task demands were equalized by increasing the drop height for males. Joint energetics were measured while landing from the two heights. Multivariate repeated measures ANOVAs compared the magnitude of sex differences in joint energetics between conditions. The multivariate test for absolute energy absorption was significant (P<0.01). The magnitude of sex difference in energy absorption was greater at the hip and knee (both P<0.01), but not the ankle (P=0.43) during the equalized condition compared to the standardized and exaggerated conditions (all P<0.01). There was no difference in the magnitude of sex differences between equalized, standardized and exaggerated conditions for relative energy absorption (P=0.18). Equalizing task demands increased the difference in absolute hip and knee energy absorption between sexes, but had no effect on relative joint contributions to total energy absorption. Sex differences in energy absorption are likely influenced by factors other than differences in relative task demands. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Skyscraping Feat

ERIC Educational Resources Information Center

Roberts, Sarah A.; Lee, Jean S.

2013-01-01

Research shows that the greatest gains in student learning in mathematics classrooms occur in classrooms in which there is sustained use of high cognitive demanding tasks throughout instruction (Boston and Smith 2009). High cognitive demanding tasks, which this article will refer to as rich tasks, are mathematics problems that are complex, less…

Posing Cognitively Demanding Tasks to All Students

ERIC Educational Resources Information Center

Lambert, Rachel; Stylianou, Despina A.

2013-01-01

Cognitively demanding tasks (CDT) (Stein et al. 2000) are necessary for the development of students' mathematical reasoning skills. Research is unequivocal on the importance of giving students opportunities to engage in such tasks. Although current reform efforts call for mathematics learning for "all" students, learners who…

The effect of augmented real-time image guidance on task workload during endoscopic sinus surgery.

PubMed

Dixon, Benjamin J; Chan, Harley; Daly, Michael J; Vescan, Allan D; Witterick, Ian J; Irish, Jonathan C

2012-01-01

Due to proximity to critical structures, the need for spatial awareness during endoscopic sinus surgery (ESS) is essential. We have developed an augmented, real-time image-guided surgery (ART-IGS) system that provides live navigational data and proximity alerts to the operating surgeon during ablation. We wished to test the hypothesis that task workload would be reduced when using this technology. A trial involved 8 otolaryngology residents and fellows performing ESS on cadaveric specimens; 1 side in a conventional method (control) and 1 side with ART-IGS. After computed tomography scanning, anatomical contouring, and registration of the head, a three-dimensional (3D) virtual endoscopic view, ablative tool tracking, and proximity alerts were enabled. Each subject completed ESS tasks and rated their workload during and after the exercise using the National Aeronautics and Space Administration (NASA) Task Load Index (TLX). A questionnaire and open feedback interview were completed after the procedure. There was a significant reduction in mental demand, temporal demand, effort, and frustration when using the ART-IGS system in comparison to the control (p < 0.02). Perceived performance was increased (p = 0.02). Most subjects agreed that the system was sufficiently accurate, caused minimal interruption, and increased confidence. Optical tracking line-of-sight issues were frequently cited as the main limitation early in the study; however, this was largely resolved. ART-IGS reduces task workload for trainees performing ESS. Live navigation and alert zones may be a valuable intraoperative teaching aid. Copyright © 2012 American Rhinologic Society-American Academy of Otolaryngic Allergy, LLC.

Network Controllability in the Inferior Frontal Gyrus Relates to Controlled Language Variability and Susceptibility to TMS.

PubMed

Medaglia, John D; Harvey, Denise Y; White, Nicole; Kelkar, Apoorva; Zimmerman, Jared; Bassett, Danielle S; Hamilton, Roy H

2018-06-08

In language production, humans are confronted with considerable word selection demands. Often, we must select a word from among similar, acceptable, and competing alternative words in order to construct a sentence that conveys an intended meaning. In recent years, the left inferior frontal gyrus (LIFG) has been identified as critical to this ability. Despite a recent emphasis on network approaches to understanding language, how the LIFG interacts with the brain's complex networks to facilitate controlled language performance remains unknown. Here, we take a novel approach to understand word selection as a network control process in the brain. Using an anatomical brain network derived from high-resolution diffusion spectrum imaging (DSI), we computed network controllability underlying the site of transcranial magnetic stimulation in the LIFG between administrations of language tasks that vary in response (cognitive control) demands: open-response (word generation) vs. closed-response (number naming) tasks. We find that a statistic that quantifies the LIFG's theoretically predicted control of communication across modules in the human connectome explains TMS-induced changes in open-response language task performance only. Moreover, we find that a statistic that quantifies the LIFG's theoretically predicted control of difficult-to-reach states explains vulnerability to TMS in the closed-ended (but not open-ended) response task. These findings establish a link between network controllability, cognitive function, and TMS effects. SIGNIFICANCE STATEMENT This work illustrates that network control statistics applied to anatomical connectivity data demonstrate relationships with cognitive variability during controlled language tasks and TMS effects. Copyright © 2018 the authors.

Benefits of interhemispheric integration on the Japanese Kana script-matching tasks.

PubMed

Yoshizaki, K; Tsuji, Y

2000-02-01

We tested Banich's hypothesis that the benefits of bihemispheric processing were enhanced as task complexity increased, when some procedural shortcomings in the previous studies were overcome by using Japanese Kana script-matching tasks. In Exp. 1, the 20 right-handed subjects were given the Physical-Identity task (Katakana-Katakana scripts matching) and the Name-Identity task (Katakana-Hiragana scripts matching). On both tasks, a pair of Kana scripts was tachistoscopically presented in the left, right, and bilateral visual fields. Distractor stimuli were also presented with target Kana scripts on both tasks to equate the processing load between the hemispheres. Analysis showed that, while a bilateral visual-field advantage was found on the name-identity task, a unilateral visual-field advantage was found on the physical-identity task, suggesting that, as the computational complexity of the encoding stage was enhanced, the benefits of bilateral hemispheric processing increased. In Exp. 2, the 16 right-handed subjects were given the same physical-identity task as in Exp. 1, except Hiragana scripts were used as distractors instead of digits to enhance task difficulty. Analysis showed no differences in performance between the unilateral and bilateral visual fields. Taking into account these results of physical-identity tasks for both Exps. 1 and 2, enhancing task demand in the stage of ignoring distractors made the unilateral visual-field advantage obtained in Exp. 1 disappear in Exp. 2. These results supported Banich's hypothesis.

Is Set Shifting Really Impaired in Trait Anxiety? Only When Switching Away from an Effortfully Established Task Set

PubMed Central

Gustavson, Daniel E.; Altamirano, Lee J.; Johnson, Daniel P.; Whisman, Mark A.; Miyake, Akira

2016-01-01

The current study investigated whether trait anxiety was systematically related to task-set shifting performance, using a task-switching paradigm in which one task was more attentionally demanding than the other. Specifically, taking advantage of a well-established phenomenon known as asymmetric switch costs, we tested the hypothesis that the association between trait anxiety and task-set shifting is most clearly observed when individuals must switch away from a more attentionally demanding task for which it was necessary to effortfully establish an appropriate task set. Ninety-one young adults completed an asymmetric switching task and trait-level mood questionnaires. Results indicated that higher levels of trait anxiety were systematically associated with greater asymmetry in reaction-time (RT) switch costs. Specifically, the RT costs for switching from the more attentionally demanding task to the less demanding task were significantly greater with higher levels of trait anxiety, whereas the RT costs for switching in the opposite direction were not significantly associated with trait anxiety levels. Further analyses indicated that these associations were not attributable to comorbid dysphoria or worry. These results suggest that levels of trait anxiety may not be related to general set-shifting ability per se, but, rather, that anxiety-specific effects may primarily be restricted to when one must efficiently switch away from (or let go of) an effortfully established task set. PMID:27429194

Following the time course of face gender and expression processing: a task-dependent ERP study.

PubMed

Valdés-Conroy, Berenice; Aguado, Luis; Fernández-Cahill, María; Romero-Ferreiro, Verónica; Diéguez-Risco, Teresa

2014-05-01

The effects of task demands and the interaction between gender and expression in face perception were studied using event-related potentials (ERPs). Participants performed three different tasks with male and female faces that were emotionally inexpressive or that showed happy or angry expressions. In two of the tasks (gender and expression categorization) facial properties were task-relevant while in a third task (symbol discrimination) facial information was irrelevant. Effects of expression were observed on the visual P100 component under all task conditions, suggesting the operation of an automatic process that is not influenced by task demands. The earliest interaction between expression and gender was observed later in the face-sensitive N170 component. This component showed differential modulations by specific combinations of gender and expression (e.g., angry male vs. angry female faces). Main effects of expression and task were observed in a later occipito-temporal component peaking around 230 ms post-stimulus onset (EPN or early posterior negativity). Less positive amplitudes in the presence of angry faces and during performance of the gender and expression tasks were observed. Finally, task demands also modulated a positive component peaking around 400 ms (LPC, or late positive complex) that showed enhanced amplitude for the gender task. The pattern of results obtained here adds new evidence about the sequence of operations involved in face processing and the interaction of facial properties (gender and expression) in response to different task demands. Copyright © 2014 Elsevier B.V. All rights reserved.

Adaptive allocation of decisionmaking responsibility between human and computer in multitask situations

NASA Technical Reports Server (NTRS)

Chu, Y.-Y.; Rouse, W. B.

1979-01-01

As human and computer come to have overlapping decisionmaking abilities, a dynamic or adaptive allocation of responsibilities may be the best mode of human-computer interaction. It is suggested that the computer serve as a backup decisionmaker, accepting responsibility when human workload becomes excessive and relinquishing responsibility when workload becomes acceptable. A queueing theory formulation of multitask decisionmaking is used and a threshold policy for turning the computer on/off is proposed. This policy minimizes event-waiting cost subject to human workload constraints. An experiment was conducted with a balanced design of several subject runs within a computer-aided multitask flight management situation with different task demand levels. It was found that computer aiding enhanced subsystem performance as well as subjective ratings. The queueing model appears to be an adequate representation of the multitask decisionmaking situation, and to be capable of predicting system performance in terms of average waiting time and server occupancy. Server occupancy was further found to correlate highly with the subjective effort ratings.

Pulling smarties out of a bag: a Headed Records analysis of children's recall of their own past beliefs.

PubMed

Barreau, S; Morton, J

1999-11-09

The work reported provides an information processing account of young children's performance on the Smarties task (Perner, J., Leekam, S.R., & Wimmer, H. 1987, Three-year-olds' difficulty with false belief: the case for a conceptual deficit. British Journal of Developmental Psychology, 5, 125-137). In this task, a 3-year-old is shown a Smarties tube and asked about the supposed contents. The true contents, pencils, is then revealed, and the majority of 3-year-olds cannot recall their initial belief that the tube contained Smarties. The theoretical analysis, based on the Headed Records framework (Morton, J., Hammersley, R.J., & Bekerian, D.A. 1985, Headed records: a model for memory and its failures, Cognition, 20, 1-23), focuses on the computational conditions that are required to resolve the Smarties task; on the possible limitations in the developing memory system that may lead to a computational breakdown; and on ways of bypassing such limitations to ensure correct resolution. The design, motivated by this analysis, is a variation on Perner's Smarties task. Instead of revealing the tube's contents immediately after establishing the child's beliefs about it, these contents were then transferred to a bag and a (false) belief about the bag's contents established. Only then were the true contents of the bag revealed. The same procedure (different contents) was carried out a week later. As predicted children's performance was better (a) in the 'tube' condition; and (b) on the second test. Consistent with the proposed analysis, the data show that when the computational demands imposed by the original task are reduced, young children can and do remember what they had thought about the contents of the tube even after its true contents are revealed.

Fighter pilots' heart rate, heart rate variation and performance during instrument approaches.

PubMed

Mansikka, Heikki; Simola, Petteri; Virtanen, Kai; Harris, Don; Oksama, Lauri

2016-10-01

Fighter pilots' heart rate (HR), heart rate variation (HRV) and performance during instrument approaches were examined. The subjects were required to fly instrument approaches in a high-fidelity simulator under various levels of task demand. The task demand was manipulated by increasing the load on the subjects by reducing the range at which they commenced the approach. HR and the time domain components of HRV were used as measures of pilot mental workload (PMWL). The findings of this study indicate that HR and HRV are sensitive to varying task demands. HR and HRV were able to distinguish the level of PMWL after which the subjects were no longer able to cope with the increasing task demands and their instrument landing system performance fell to a sub-standard level. The major finding was the HR/HRV's ability to differentiate the sub-standard performance approaches from the high-performance approaches. Practitioner Summary: This paper examined if HR and HRV were sensitive to varying task demands in a fighter aviation environment and if these measures were related to variations in pilot's performance.

Explicit attention interferes with selective emotion processing in human extrastriate cortex.

PubMed

Schupp, Harald T; Stockburger, Jessica; Bublatzky, Florian; Junghöfer, Markus; Weike, Almut I; Hamm, Alfons O

2007-02-22

Brain imaging and event-related potential studies provide strong evidence that emotional stimuli guide selective attention in visual processing. A reflection of the emotional attention capture is the increased Early Posterior Negativity (EPN) for pleasant and unpleasant compared to neutral images (approximately 150-300 ms poststimulus). The present study explored whether this early emotion discrimination reflects an automatic phenomenon or is subject to interference by competing processing demands. Thus, emotional processing was assessed while participants performed a concurrent feature-based attention task varying in processing demands. Participants successfully performed the primary visual attention task as revealed by behavioral performance and selected event-related potential components (Selection Negativity and P3b). Replicating previous results, emotional modulation of the EPN was observed in a task condition with low processing demands. In contrast, pleasant and unpleasant pictures failed to elicit increased EPN amplitudes compared to neutral images in more difficult explicit attention task conditions. Further analyses determined that even the processing of pleasant and unpleasant pictures high in emotional arousal is subject to interference in experimental conditions with high task demand. Taken together, performing demanding feature-based counting tasks interfered with differential emotion processing indexed by the EPN. The present findings demonstrate that taxing processing resources by a competing primary visual attention task markedly attenuated the early discrimination of emotional from neutral picture contents. Thus, these results provide further empirical support for an interference account of the emotion-attention interaction under conditions of competition. Previous studies revealed the interference of selective emotion processing when attentional resources were directed to locations of explicitly task-relevant stimuli. The present data suggest that interference of emotion processing by competing task demands is a more general phenomenon extending to the domain of feature-based attention. Furthermore, the results are inconsistent with the notion of effortlessness, i.e., early emotion discrimination despite concurrent task demands. These findings implicate to assess the presumed automatic nature of emotion processing at the level of specific aspects rather than considering automaticity as an all-or-none phenomenon.

Explicit attention interferes with selective emotion processing in human extrastriate cortex

PubMed Central

Schupp, Harald T; Stockburger, Jessica; Bublatzky, Florian; Junghöfer, Markus; Weike, Almut I; Hamm, Alfons O

2007-01-01

Background Brain imaging and event-related potential studies provide strong evidence that emotional stimuli guide selective attention in visual processing. A reflection of the emotional attention capture is the increased Early Posterior Negativity (EPN) for pleasant and unpleasant compared to neutral images (~150–300 ms poststimulus). The present study explored whether this early emotion discrimination reflects an automatic phenomenon or is subject to interference by competing processing demands. Thus, emotional processing was assessed while participants performed a concurrent feature-based attention task varying in processing demands. Results Participants successfully performed the primary visual attention task as revealed by behavioral performance and selected event-related potential components (Selection Negativity and P3b). Replicating previous results, emotional modulation of the EPN was observed in a task condition with low processing demands. In contrast, pleasant and unpleasant pictures failed to elicit increased EPN amplitudes compared to neutral images in more difficult explicit attention task conditions. Further analyses determined that even the processing of pleasant and unpleasant pictures high in emotional arousal is subject to interference in experimental conditions with high task demand. Taken together, performing demanding feature-based counting tasks interfered with differential emotion processing indexed by the EPN. Conclusion The present findings demonstrate that taxing processing resources by a competing primary visual attention task markedly attenuated the early discrimination of emotional from neutral picture contents. Thus, these results provide further empirical support for an interference account of the emotion-attention interaction under conditions of competition. Previous studies revealed the interference of selective emotion processing when attentional resources were directed to locations of explicitly task-relevant stimuli. The present data suggest that interference of emotion processing by competing task demands is a more general phenomenon extending to the domain of feature-based attention. Furthermore, the results are inconsistent with the notion of effortlessness, i.e., early emotion discrimination despite concurrent task demands. These findings implicate to assess the presumed automatic nature of emotion processing at the level of specific aspects rather than considering automaticity as an all-or-none phenomenon. PMID:17316444

Seeing it my way: a case of a selective deficit in inhibiting self-perspective.

PubMed

Samson, Dana; Apperly, Ian A; Kathirgamanathan, Umalini; Humphreys, Glyn W

2005-05-01

Little is known about the functional and neural architecture of social reasoning, one major obstacle being that we crucially lack the relevant tools to test potentially different social reasoning components. In the case of belief reasoning, previous studies have tried to separate the processes involved in belief reasoning per se from those involved in the processing of the high incidental demands such as the working memory demands of typical belief tasks. In this study, we developed new belief tasks in order to disentangle, for the first time, two perspective taking components involved in belief reasoning: (i) the ability to inhibit one's own perspective (self-perspective inhibition); and (ii) the ability to infer someone else's perspective as such (other-perspective taking). The two tasks had similar demands in other-perspective taking as they both required the participant to infer that a character has a false belief about an object's location. However, the tasks varied in the self-perspective inhibition demands. In the task with the lowest self-perspective inhibition demands, at the time the participant had to infer the character's false belief, he or she had no idea what the new object's location was. In contrast, in the task with the highest self-perspective inhibition demands, at the time the participant had to infer the character's false belief, he or she knew where the object was actually located (and this knowledge had thus to be inhibited). The two tasks were presented to a stroke patient, WBA, with right prefrontal and temporal damage. WBA performed well in the low-inhibition false-belief task but showed striking difficulty in the task placing high self-perspective inhibition demands, showing a selective deficit in inhibiting self-perspective. WBA also made egocentric errors in other social and visual perspective taking tasks, indicating a difficulty with belief attribution extending to the attribution of emotions, desires and visual experiences to other people. The case of WBA, together with the recent report of three patients impaired in belief reasoning even when self-perspective inhibition demands were reduced, provide the first neuropsychological evidence that the inhibition of one's own point of view and the ability to infer someone else's point of view rely on distinct neural and functional processes.

Tool use disorders after left brain damage.

PubMed

Baumard, Josselin; Osiurak, François; Lesourd, Mathieu; Le Gall, Didier

2014-01-01

In this paper we review studies that investigated tool use disorders in left-brain damaged (LBD) patients over the last 30 years. Four tasks are classically used in the field of apraxia: Pantomime of tool use, single tool use, real tool use and mechanical problem solving. Our aim was to address two issues, namely, (1) the role of mechanical knowledge in real tool use and (2) the cognitive mechanisms underlying pantomime of tool use, a task widely employed by clinicians and researchers. To do so, we extracted data from 36 papers and computed the difference between healthy subjects and LBD patients. On the whole, pantomime of tool use is the most difficult task and real tool use is the easiest one. Moreover, associations seem to appear between pantomime of tool use, real tool use and mechanical problem solving. These results suggest that the loss of mechanical knowledge is critical in LBD patients, even if all of those tasks (and particularly pantomime of tool use) might put differential demands on semantic memory and working memory.

Tool use disorders after left brain damage

PubMed Central

Baumard, Josselin; Osiurak, François; Lesourd, Mathieu; Le Gall, Didier

2014-01-01

In this paper we review studies that investigated tool use disorders in left-brain damaged (LBD) patients over the last 30 years. Four tasks are classically used in the field of apraxia: Pantomime of tool use, single tool use, real tool use and mechanical problem solving. Our aim was to address two issues, namely, (1) the role of mechanical knowledge in real tool use and (2) the cognitive mechanisms underlying pantomime of tool use, a task widely employed by clinicians and researchers. To do so, we extracted data from 36 papers and computed the difference between healthy subjects and LBD patients. On the whole, pantomime of tool use is the most difficult task and real tool use is the easiest one. Moreover, associations seem to appear between pantomime of tool use, real tool use and mechanical problem solving. These results suggest that the loss of mechanical knowledge is critical in LBD patients, even if all of those tasks (and particularly pantomime of tool use) might put differential demands on semantic memory and working memory. PMID:24904487

Spatial effects, sampling errors, and task specialization in the honey bee.

PubMed

Johnson, B R

2010-05-01

Task allocation patterns should depend on the spatial distribution of work within the nest, variation in task demand, and the movement patterns of workers, however, relatively little research has focused on these topics. This study uses a spatially explicit agent based model to determine whether such factors alone can generate biases in task performance at the individual level in the honey bees, Apis mellifera. Specialization (bias in task performance) is shown to result from strong sampling error due to localized task demand, relatively slow moving workers relative to nest size, and strong spatial variation in task demand. To date, specialization has been primarily interpreted with the response threshold concept, which is focused on intrinsic (typically genotypic) differences between workers. Response threshold variation and sampling error due to spatial effects are not mutually exclusive, however, and this study suggests that both contribute to patterns of task bias at the individual level. While spatial effects are strong enough to explain some documented cases of specialization; they are relatively short term and not explanatory for long term cases of specialization. In general, this study suggests that the spatial layout of tasks and fluctuations in their demand must be explicitly controlled for in studies focused on identifying genotypic specialists.

Adapting to Changing Memory Retrieval Demands: Evidence from Event-Related Potentials

ERIC Educational Resources Information Center

Benoit, Roland G.; Werkle-Bergner, Markus; Mecklinger, Axel; Kray, Jutta

2009-01-01

This study investigated preparatory processes involved in adapting to changing episodic memory retrieval demands. Event-related potentials (ERPs) were recorded while participants performed a general old/new recognition task and a specific task that also required retrieval of perceptual details. The relevant task remained either constant or changed…

Predicting dual-task performance with the Multiple Resources Questionnaire (MRQ).

PubMed

Boles, David B; Bursk, Jonathan H; Phillips, Jeffrey B; Perdelwitz, Jason R

2007-02-01

The objective was to assess the validity of the Multiple Resources Questionnaire (MRQ) in predicting dual-task interference. Subjective workload measures such as the Subjective Workload Assessment Technique (SWAT) and NASA Task Load Index are sensitive to single-task parameters and dual-task loads but have not attempted to measure workload in particular mental processes. An alternative is the MRQ. In Experiment 1, participants completed simple laboratory tasks and the MRQ after each. Interference between tasks was then correlated to three different task similarity metrics: profile similarity, based on r(2) between ratings; overlap similarity, based on summed minima; and overall demand, based on summed ratings. Experiment 2 used similar methods but more complex computer-based games. In Experiment 1 the MRQ moderately predicted interference (r = +.37), with no significant difference between metrics. In Experiment 2 the metric effect was significant, with overlap similarity excelling in predicting interference (r = +.83). Mean ratings showed high diagnosticity in identifying specific mental processing bottlenecks. The MRQ shows considerable promise as a cognitive-process-sensitive workload measure. Potential applications of the MRQ include the identification of dual-processing bottlenecks as well as process overloads in single tasks, preparatory to redesign in areas such as air traffic management, advanced flight displays, and medical imaging.

Psychology of knowledge representation.

PubMed

Grimm, Lisa R

2014-05-01

Every cognitive enterprise involves some form of knowledge representation. Humans represent information about the external world and internal mental states, like beliefs and desires, and use this information to meet goals (e.g., classification or problem solving). Unfortunately, researchers do not have direct access to mental representations. Instead, cognitive scientists design experiments and implement computational models to develop theories about the mental representations present during task performance. There are several main types of mental representation and corresponding processes that have been posited: spatial, feature, network, and structured. Each type has a particular structure and a set of processes that are capable of accessing and manipulating information within the representation. The structure and processes determine what information can be used during task performance and what information has not been represented at all. As such, the different types of representation are likely used to solve different kinds of tasks. For example, structured representations are more complex and computationally demanding, but are good at representing relational information. Researchers interested in human psychology would benefit from considering how knowledge is represented in their domain of inquiry. For further resources related to this article, please visit the WIREs website. The author has declared no conflicts of interest for this article. © 2014 John Wiley & Sons, Ltd.

SEASAT economic assessment. Volume 10: The SATIL 2 program (a program for the evaluation of the costs of an operational SEASAT system as a function of operational requirements and reliability. [computer programs for economic analysis and systems analysis of SEASAT satellite systems

NASA Technical Reports Server (NTRS)

1975-01-01

The SATIL 2 computer program was developed to assist with the programmatic evaluation of alternative approaches to establishing and maintaining a specified mix of operational sensors on spacecraft in an operational SEASAT system. The program computes the probability distributions of events (i.e., number of launch attempts, number of spacecraft purchased, etc.), annual recurring cost, and present value of recurring cost. This is accomplished for the specific task of placing a desired mix of sensors in orbit in an optimal fashion in order to satisfy a specified sensor demand function. Flow charts are shown, and printouts of the programs are given.

Group benefits in joint perceptual tasks-a review.

PubMed

Wahn, Basil; Kingstone, Alan; König, Peter

2018-05-12

In daily life, humans often perform perceptual tasks together to reach a shared goal. In these situations, individuals may collaborate (e.g., by distributing task demands) to perform the task better than when the task is performed alone (i.e., attain a group benefit). In this review, we identify the factors influencing if, and to what extent, a group benefit is attained and provide a framework of measures to assess group benefits in perceptual tasks. In particular, we integrate findings from two frequently investigated joint perceptual tasks: visuospatial tasks and decision-making tasks. For both task types, we find that an exchange of information between coactors is critical to improve joint performance. Yet, the type of exchanged information and how coactors collaborate differs between tasks. In visuospatial tasks, coactors exchange information about the performed actions to distribute task demands. In perceptual decision-making tasks, coactors exchange their confidence on their individual perceptual judgments to negotiate a joint decision. We argue that these differences can be explained by the task structure: coactors distribute task demands if a joint task allows for a spatial division and stimuli can be accurately processed by one individual. Otherwise, they perform the task individually and then integrate their individual judgments. © 2018 New York Academy of Sciences.

Demand characteristics, pre-test attitudes and time-on-task trends in the effects of chewing gum on attention and reported mood in healthy volunteers.

PubMed

Allen, A P; Smith, A P

2012-10-01

Previous research has indicated that chewing gum enhances reported alertness, but has variable effects on attention. Demand characteristics may explain these effects. The current study investigated the effects of gum and demand characteristics on attention and reported mood over time. Participants completed measures of mood and attention, with and without chewing gum. To manipulate demand characteristics, they were told that the hypothesised effect of gum was either positive or negative, or no hypothesis was mentioned. Attitudes towards gum were assessed pre- and post-manipulation. Gum increased reported alertness; this effect was only significant for positive and neutral demand characteristics. Vigilance accuracy was reduced for chewing gum, but only in the fourth minute of the task, and gum reduced focussed attention accuracy, but only for the first 64 trials. Demand characteristics did not moderate time-on-task effects. Gum improved selective attention. A positive effect on response organisation was observed; this was significant when demand characteristics and pre-test attitudes to gum were both negative. The results suggest that demand characteristics moderate effects on self-reported alertness and response organisation, but cannot explain time-on-task effects or variable main effects on other aspects of attention. Copyright © 2012 Elsevier Ltd. All rights reserved.

The influence of an auditory-memory attention-demanding task on postural control in blind persons.

PubMed

Melzer, Itshak; Damry, Elad; Landau, Anat; Yagev, Ronit

2011-05-01

In order to evaluate the effect of an auditory-memory attention-demanding task on balance control, nine blind adults were compared to nine age-gender-matched sighted controls. This issue is particularly relevant for the blind population in which functional assessment of postural control has to be revealed through "real life" motor and cognitive function. The study aimed to explore whether an auditory-memory attention-demanding cognitive task would influence postural control in blind persons and compare this with blindfolded sighted persons. Subjects were instructed to minimize body sway during narrow base upright standing on a single force platform under two conditions: 1) standing still (single task); 2) as in 1) while performing an auditory-memory attention-demanding cognitive task (dual task). Subjects in both groups were required to stand blindfolded with their eyes closed. Center of Pressure displacement data were collected and analyzed using summary statistics and stabilogram-diffusion analysis. Blind and sighted subjects had similar postural sway in eyes closed condition. However, for dual compared to single task, sighted subjects show significant decrease in postural sway while blind subjects did not. The auditory-memory attention-demanding cognitive task had no interference effect on balance control on blind subjects. It seems that sighted individuals used auditory cues to compensate for momentary loss of vision, whereas blind subjects did not. This may suggest that blind and sighted people use different sensorimotor strategies to achieve stability. Copyright © 2010 Elsevier Ltd. All rights reserved.

A framework for analyzing the cognitive complexity of computer-assisted clinical ordering.

PubMed

Horsky, Jan; Kaufman, David R; Oppenheim, Michael I; Patel, Vimla L

2003-01-01

Computer-assisted provider order entry is a technology that is designed to expedite medical ordering and to reduce the frequency of preventable errors. This paper presents a multifaceted cognitive methodology for the characterization of cognitive demands of a medical information system. Our investigation was informed by the distributed resources (DR) model, a novel approach designed to describe the dimensions of user interfaces that introduce unnecessary cognitive complexity. This method evaluates the relative distribution of external (system) and internal (user) representations embodied in system interaction. We conducted an expert walkthrough evaluation of a commercial order entry system, followed by a simulated clinical ordering task performed by seven clinicians. The DR model was employed to explain variation in user performance and to characterize the relationship of resource distribution and ordering errors. The analysis revealed that the configuration of resources in this ordering application placed unnecessarily heavy cognitive demands on the user, especially on those who lacked a robust conceptual model of the system. The resources model also provided some insight into clinicians' interactive strategies and patterns of associated errors. Implications for user training and interface design based on the principles of human-computer interaction in the medical domain are discussed.

Speech-based interaction with in-vehicle computers: the effect of speech-based e-mail on drivers' attention to the roadway.

PubMed

Lee, J D; Caven, B; Haake, S; Brown, T L

2001-01-01

As computer applications for cars emerge, a speech-based interface offers an appealing alternative to the visually demanding direct manipulation interface. However, speech-based systems may pose cognitive demands that could undermine driving safety. This study used a car-following task to evaluate how a speech-based e-mail system affects drivers' response to the periodic braking of a lead vehicle. The study included 24 drivers between the ages of 18 and 24 years. A baseline condition with no e-mail system was compared with a simple and a complex e-mail system in both simple and complex driving environments. The results show a 30% (310 ms) increase in reaction time when the speech-based system is used. Subjective workload ratings and probe questions also indicate that speech-based interaction introduces a significant cognitive load, which was highest for the complex e-mail system. These data show that a speech-based interface is not a panacea that eliminates the potential distraction of in-vehicle computers. Actual or potential applications of this research include design of in-vehicle information systems and evaluation of their contributions to driver distraction.

The influence of time on task on mind wandering and visual working memory.

PubMed

Krimsky, Marissa; Forster, Daniel E; Llabre, Maria M; Jha, Amishi P

2017-12-01

Working memory relies on executive resources for successful task performance, with higher demands necessitating greater resource engagement. In addition to mnemonic demands, prior studies suggest that internal sources of distraction, such as mind wandering (i.e., having off-task thoughts) and greater time on task, may tax executive resources. Herein, the consequences of mnemonic demand, mind wandering, and time on task were investigated during a visual working memory task. Participants (N=143) completed a delayed-recognition visual working memory task, with mnemonic load for visual objects manipulated across trials (1 item=low load; 2 items=high load) and subjective mind wandering assessed intermittently throughout the experiment using a self-report Likert-type scale (1=on-task, 6=off-task). Task performance (correct/incorrect response) and self-reported mind wandering data were evaluated by hierarchical linear modeling to track trial-by-trial fluctuations. Performance declined with greater time on task, and the rate of decline was steeper for high vs low load trials. Self-reported mind wandering increased over time, and significantly varied asa function of both load and time on task. Participants reported greater mind wandering at the beginning of the experiment for low vs. high load trials; however, with greater time on task, more mind wandering was reported during high vs. low load trials. These results suggest that the availability of executive resources in support of working memory maintenance processes fluctuates in a demand-sensitive manner with time on task, and may be commandeered by mind wandering. Copyright © 2017 Elsevier B.V. All rights reserved.

The Effect of Interruption Duration and Demand on Resuming Suspended Goals

ERIC Educational Resources Information Center

Monk, Christopher A.; Trafton, J. Gregory; Boehm-Davis, Deborah A.

2008-01-01

The time to resume task goals after an interruption varied depending on the duration and cognitive demand of interruptions, as predicted by the memory for goals model (Altmann & Trafton, 2002). Three experiments using an interleaved tasks interruption paradigm showed that longer and more demanding interruptions led to longer resumption times in a…

Affect Response to Simulated Information Attack during Complex Task Performance

DTIC Science & Technology

2014-12-02

AND FRUSTRATION ........................ 42 FIGURE 27. TASK LOAD INDEX OF MENTAL DEMAND, TEMPORAL DEMAND, AND PHYSICAL DEMAND...situational awareness, affect, and trait characteristics interact with human performance during cyberspace attacks in the physical and information...Operator state was manipulated using emotional stimulation portrayed through the presentation of video segments. The effect of emotions on

Effects of Cognitive Demand on Situational Interest and Running Task Performances

ERIC Educational Resources Information Center

Zhu, Xihe; Chen, Senlin

2017-01-01

This study examined the effect of cognitive demand on situational interest and performance using running tasks in physical education. Adolescents (N = 179) participated in a field study involving three different levels of cognitive demand. Running performances and situational interest were measured four times with a testing interval of seven days.…

Prospective memory and working memory: asymmetrical effects during frontal lobe TMS stimulation.

PubMed

Basso, Demis; Ferrari, Marcella; Palladino, Paola

2010-09-01

The role of working memory (WM) for the realization of an intended action (prospective memory, PM) has been debated in recent neuropsychological literature. The present study aimed to assess whether WM and PM share resources or are, alternatively, two distinct mechanisms. A verbal task was used, which manipulated the cognitive demand of both WM and PM dimensions on an event-based prospective task. Transcranial magnetic stimulation (TMS) was also employed to clarify the causal contribution of frontal areas previously related to WM, to the PM process. The prospective task required the participant to respond whenever a word appeared which had been presented before the beginning of the task. Two ongoing tasks were administered: an updating WM task (in two conditions of medium and high WM demands) and a lexical decision task (representing a low WM demand). In the first two experiments, higher PM demand affected WM only at higher loads, but the PM load effect was independent of WM, showing asymmetrical behavioural effects. In the third experiment, single pulse TMS was applied to left and right dorsolateral prefrontal cortices. When applied to the experimental sites, stimulation increased error rates of the PM task, while the effect was only marginal in the WM task. The effect was bilateral, since there was no difference between left and right stimulation sites. These findings demonstrated, from both behavioural and neurofunctional perspectives, that WM and PM processes are not based on the same memory system, but PM may require WM resources at high demand. Copyright 2010 Elsevier Ltd. All rights reserved.

U.S. Army physical demands study: Identification and validation of the physically demanding tasks of combat arms occupations.

PubMed

Sharp, Marilyn A; Cohen, Bruce S; Boye, Michael W; Foulis, Stephen A; Redmond, Jan E; Larcom, Kathleen; Hydren, Jay R; Gebhardt, Deborah L; Canino, Maria C; Warr, Bradley J; Zambraski, Edward J

2017-11-01

In 2013, the U.S. Army began developing physical tests to predict a recruit's ability to perform the critical, physically demanding tasks (CPDTs) of combat arms jobs previously not open to women. The purpose of this paper is to describe the methodology and results of analyses of the accuracy and inclusiveness of the critical physically demanding task list. While the job analysis included seven combat arms jobs, only data from the 19D Cavalry Scout occupation are presented as the process was similar for all seven jobs. Job analysis METHODS: As the foundation, senior subject matter experts from each job reviewed materials and reached consensus on the CPDTs and performance standards for each job. The list was reviewed by Army leadership and provided to the researchers. The job analysis consisted of reviewing job and task related documents and field manuals, observing >900 soldiers performing the 32 CPDTs, conducting two focus groups for each job, and analyzing responses to widely distributed job analysis questionnaires. Of the 32 CPDTs identified for seven combat jobs, nine were relevant to 19D soldiers. Focus group discussions and job analysis questionnaire results supported the tasks and standards identified by subject matter experts while also identifying additional tasks. The tasks identified by subject matter experts were representative of the physically demanding aspects of the 19D occupation. Published by Elsevier Ltd.

Hyperactivity in boys with attention-deficit/hyperactivity disorder (ADHD): The role of executive and non-executive functions.

PubMed

Hudec, Kristen L; Alderson, R Matt; Patros, Connor H G; Lea, Sarah E; Tarle, Stephanie J; Kasper, Lisa J

2015-01-01

Motor activity of boys (age 8-12 years) with (n=19) and without (n=18) ADHD was objectively measured with actigraphy across experimental conditions that varied with regard to demands on executive functions. Activity exhibited during two n-back (1-back, 2-back) working memory tasks was compared to activity during a choice-reaction time (CRT) task that placed relatively fewer demands on executive processes and during a simple reaction time (SRT) task that required mostly automatic processing with minimal executive demands. Results indicated that children in the ADHD group exhibited greater activity compared to children in the non-ADHD group. Further, both groups exhibited the greatest activity during conditions with high working memory demands, followed by the reaction time and control task conditions, respectively. The findings indicate that large-magnitude increases in motor activity are predominantly associated with increased demands on working memory, though demands on non-executive processes are sufficient to elicit small to moderate increases in motor activity as well. Published by Elsevier Ltd.

Longitudinal effects of bilingualism on dual-tasking

PubMed Central

Josefsson, Maria; Marsh, John E.; Hansson, Patrik; Ljungberg, Jessica K.

2017-01-01

An ongoing debate surrounds whether bilinguals outperform monolinguals in tests of executive processing. The aim of this study was to investigate if there are long-term (10 year) bilingual advantages in executive processing, as indexed by dual-task performance, in a sample that were 40–65 years at baseline. The bilingual (n = 24) and monolingual (n = 24) participants were matched on age, sex, education, fluid intelligence, and study sample. Participants performed free-recall for a 12-item list in three dual-task settings wherein they sorted cards either during encoding, retrieval, or during both encoding and retrieval of the word-list. Free recall without card sorting was used as a reference to compute dual-task costs. The results showed that bilinguals significantly outperformed monolinguals when they performed card-sorting during both encoding and retrieval of the word-list, the condition that presumably placed the highest demands on executive functioning. However, dual-task costs increased over time for bilinguals relative to monolinguals, a finding that is possibly influenced by retirement age and limited use of second language in the bilingual group. PMID:29281654

Rule-Based Categorization Deficits in Focal Basal Ganglia Lesion and Parkinson’s Disease Patients

PubMed Central

Ell, Shawn W.; Weinstein, Andrea; Ivry, Richard B.

2010-01-01

Patients with basal ganglia (BG) pathology are consistently found to be impaired on rule-based category learning tasks in which learning is thought to depend upon the use of an explicit, hypothesis-guided strategy. The factors that influence this impairment remain unclear. Moreover, it remains unknown if the impairments observed in patients with degenerative disorders such as Parkinson's disease (PD) are also observed in those with focal BG lesions. In the present study, we tested patients with either focal BG lesions or PD on two categorization tasks that varied in terms of their demands on selective attention and working memory. Individuals with focal BG lesions were impaired on the task in which working-memory demand was high and performed similarly to healthy controls on the task in which selective-attention demand was high. In contrast, individuals with PD were impaired on both tasks, and accuracy rates did not differ between on- and off-medication states for a subset of patients who were also tested after abstaining from dopaminergic medication. Quantitative, model-based analyses attributed the performance deficit for both groups in the task with high working-memory demand to the utilization of suboptimal strategies, whereas the PD-specific impairment on the task with high selective-attention demand was driven by the inconsistent use of an optimal strategy. These data suggest that the demands on selective attention and working memory affect the presence of impairment in patients with focal BG lesions and the nature of the impairment in patients with PD. PMID:20600196

Physiological Indices of Pilots' Abilities Under Varying Task Demands.

PubMed

Wang, Zhen; Zheng, Lingxiao; Lu, Yanyu; Fu, Shan

2016-04-01

This study investigated pilots' ability by examining the effects of flight experience and task demand on physiological reactions, and analyzing the diagnostic meanings underlying correlated parameters. A total of 12 experienced pilots and 12 less experienced pilots performed 4 simulated flight tasks, including normal and emergency situations. Fixation duration (FD), saccade rate (SR), blink rate (BR), heart rate (HR), respiration rate (RR), and respiration amplitude (RA) were measured during the tasks. More experienced pilots adapted their SR flexibly to changing task demands and had significantly lower SR than less experienced pilots during emergency tasks (29.6 ± 20.0 vs. 70.1 ± 67.1 saccades/min). BR, HR, and RR were affected by pilot experience but not by task demand. More experienced pilots had lower BR, HR, and RR than less experienced pilots during both normal tasks (BR: 14.3 ± 13.0 vs. 32.9 ± 25.8 blinks/min; HR: 72.7 ± 7.9 vs. 83.2 ± 7.2 bpm; RR: 15.4 ± 2.1 vs. 19.5 ± 5.2 breaths/min) and emergency tasks (BR: 10.2 ± 5.0 vs. 32.3 ± 20.8 blinks/min; HR: 73.3 ± 7.3 vs. 82.2 ± 11.6 bpm; RR: 15.6 ± 1.9 vs. 18.0 ± 3.2 breaths/min). FD and RA were not sensitive to either flight experience or task demand. Physiological reactions have the potential to reflect pilots' ability from different aspects. SR and BR could indicate pilots' differences in information access strategy. HR and RR could reflect a pilot's physical fitness. These findings are useful for understanding a pilot's ability.

Non-Interfering Effects of Active Post-Encoding Tasks on Episodic Memory Consolidation in Humans

PubMed Central

Varma, Samarth; Takashima, Atsuko; Krewinkel, Sander; van Kooten, Maaike; Fu, Lily; Medendorp, W. Pieter; Kessels, Roy P. C.; Daselaar, Sander M.

2017-01-01

So far, studies that investigated interference effects of post-learning processes on episodic memory consolidation in humans have used tasks involving only complex and meaningful information. Such tasks require reallocation of general or encoding-specific resources away from consolidation-relevant activities. The possibility that interference can be elicited using a task that heavily taxes our limited brain resources, but has low semantic and hippocampal related long-term memory processing demands, has never been tested. We address this question by investigating whether consolidation could persist in parallel with an active, encoding-irrelevant, minimally semantic task, regardless of its high resource demands for cognitive processing. We distinguish the impact of such a task on consolidation based on whether it engages resources that are: (1) general/executive, or (2) specific/overlapping with the encoding modality. Our experiments compared subsequent memory performance across two post-encoding consolidation periods: quiet wakeful rest and a cognitively demanding n-Back task. Across six different experiments (total N = 176), we carefully manipulated the design of the n-Back task to target general or specific resources engaged in the ongoing consolidation process. In contrast to previous studies that employed interference tasks involving conceptual stimuli and complex processing demands, we did not find any differences between n-Back and rest conditions on memory performance at delayed test, using both recall and recognition tests. Our results indicate that: (1) quiet, wakeful rest is not a necessary prerequisite for episodic memory consolidation; and (2) post-encoding cognitive engagement does not interfere with memory consolidation when task-performance has minimal semantic and hippocampally-based episodic memory processing demands. We discuss our findings with reference to resource and reactivation-led interference theories. PMID:28424596

Non-Interfering Effects of Active Post-Encoding Tasks on Episodic Memory Consolidation in Humans.

PubMed

Varma, Samarth; Takashima, Atsuko; Krewinkel, Sander; van Kooten, Maaike; Fu, Lily; Medendorp, W Pieter; Kessels, Roy P C; Daselaar, Sander M

2017-01-01

So far, studies that investigated interference effects of post-learning processes on episodic memory consolidation in humans have used tasks involving only complex and meaningful information. Such tasks require reallocation of general or encoding-specific resources away from consolidation-relevant activities. The possibility that interference can be elicited using a task that heavily taxes our limited brain resources, but has low semantic and hippocampal related long-term memory processing demands, has never been tested. We address this question by investigating whether consolidation could persist in parallel with an active, encoding-irrelevant, minimally semantic task, regardless of its high resource demands for cognitive processing. We distinguish the impact of such a task on consolidation based on whether it engages resources that are: (1) general/executive, or (2) specific/overlapping with the encoding modality. Our experiments compared subsequent memory performance across two post-encoding consolidation periods: quiet wakeful rest and a cognitively demanding n-Back task. Across six different experiments (total N = 176), we carefully manipulated the design of the n-Back task to target general or specific resources engaged in the ongoing consolidation process. In contrast to previous studies that employed interference tasks involving conceptual stimuli and complex processing demands, we did not find any differences between n-Back and rest conditions on memory performance at delayed test, using both recall and recognition tests. Our results indicate that: (1) quiet, wakeful rest is not a necessary prerequisite for episodic memory consolidation; and (2) post-encoding cognitive engagement does not interfere with memory consolidation when task-performance has minimal semantic and hippocampally-based episodic memory processing demands. We discuss our findings with reference to resource and reactivation-led interference theories.

Allocation of Attentional Resources toward a Secondary Cognitive Task Leads to Compromised Ankle Proprioceptive Performance in Healthy Young Adults

PubMed Central

Yasuda, Kazuhiro; Iimura, Naoyuki; Iwata, Hiroyasu

2014-01-01

The objective of the present study was to determine whether increased attentional demands influence the assessment of ankle joint proprioceptive ability in young adults. We used a dual-task condition, in which participants performed an ankle ipsilateral position-matching task with and without a secondary serial auditory subtraction task during target angle encoding. Two experiments were performed with two different cohorts: one in which the auditory subtraction task was easy (experiment 1a) and one in which it was difficult (experiment 1b). The results showed that, compared with the single-task condition, participants had higher absolute error under dual-task conditions in experiment 1b. The reduction in position-matching accuracy with an attentionally demanding cognitive task suggests that allocation of attentional resources toward a difficult second task can lead to compromised ankle proprioceptive performance. Therefore, these findings indicate that the difficulty level of the cognitive task might be the possible critical factor that decreased accuracy of position-matching task. We conclude that increased attentional demand with difficult cognitive task does influence the assessment of ankle joint proprioceptive ability in young adults when measured using an ankle ipsilateral position-matching task. PMID:24523966

Acute stress shifts the balance between controlled and automatic processes in prospective memory.

PubMed

Möschl, Marcus; Walser, Moritz; Plessow, Franziska; Goschke, Thomas; Fischer, Rico

2017-10-01

In everyday life we frequently rely on our abilities to postpone intentions until later occasions (prospective memory; PM) and to deactivate completed intentions even in stressful situations. Yet, little is known about the effects of acute stress on these abilities. In the present work we investigated the impact of acute stress on PM functioning under high task demands. (1) Different from previous studies, in which intention deactivation required mostly low processing demands, we used salient focal PM cues to induce high processing demands during intention-deactivation phases. (2) We systematically manipulated PM-monitoring demands in a nonfocal PM task that required participants to monitor for either one or six specific syllables that could occur in ongoing-task words. Eighty participants underwent the Trier Social Stress Test, a standardized stress induction protocol, or a standardized control situation, before performing a computerized PM task. Our primary interests were whether PM performance, PM-monitoring costs, aftereffects of completed intentions and/or commission-error risk would differ between stressed and non-stressed individuals and whether these effects would differ under varying task demands. Results revealed that PM performance and aftereffects of completed intentions during subsequent performance were not affected by acute stress induction, replicating previous findings. Under high demands on intention deactivation (focal condition), however, acute stress produced a nominal increase in erroneous PM responses after intention completion (commission errors). Most importantly, under high demands on PM monitoring (nonfocal condition), acute stress led to a substantial reduction in PM-monitoring costs. These findings support ideas of selective and demand-dependent effects of acute stress on cognitive functioning. Under high task demands, acute stress might induce a shift in processing strategy towards resource-saving behavior, which seems to increase the efficiency of PM performance (reduced monitoring costs), but might increase initial susceptibility to automatic response activation after intention completion. Copyright © 2017 Elsevier Inc. All rights reserved.

Relations of Instructional Tasks to Teacher-Student Discourse in Mathematics Classrooms of Chinese Primary Schools

ERIC Educational Resources Information Center

Ni, Yujing; Zhou, Dehui; Li, Xiaoqing; Li, Qiong

2014-01-01

This study, based on observation of 90 fifth-grade mathematics classes in Chinese elementary schools, examined how the task features, high cognitive demand, multiple representations, and multiple solution methods may relate to classroom discourse. Results indicate that high cognitive demand tasks were associated with teachers' use higher order…

EEG Patterns Related to Cognitive Tasks of Varying Complexity.

ERIC Educational Resources Information Center

Dunn, Denise A.; And Others

A study was conducted that attempted to show changes in electroencephalographic (EEG) patterns (identified using topographic EEG mapping) when children were required to perform the relatively simple task of button pressing during an eyes-open baseline session of low cognitive demand and a complex reaction time (RT) task of high cognitive demand.…

Driver-initiated distractions: examining strategic adaptation for in-vehicle task initiation.

PubMed

Horrey, William J; Lesch, Mary F

2009-01-01

Today, drivers are faced with many in-vehicle activities that are potentially distracting. In many cases, they are not passive recipients of these tasks; rather, drivers decide whether or not (or how) to perform them. In this study, we examined whether drivers, given knowledge of the upcoming road demands, would strategically delay performing in-vehicle activities until demands were reduced. Twenty drivers drove an instrumented van around a closed track that was divided into sections of varying demands and difficulty. Drivers were asked to perform one of four in-vehicle tasks (e.g., phone conversation; read a text message; find an address; pick up an object on the floor); however, they were free to decide when to initiate these tasks, provided they finish them before a given deadline. Although drivers were fully aware of the relative demands of the road, they did not tend to strategically postpone tasks--a finding that was consistent across the different tasks (p >.05). Rather, drivers tended to initiate tasks regardless of the current driving conditions. This strategy frequently led to driving errors. Given the control that drivers have over many in-vehicle distractions, interventions that focus on strategic decisions and planning may have merit.

How we can measure the non-driving-task engagement in automated driving: Comparing flow experience and workload.

PubMed

Ko, Sang Min; Ji, Yong Gu

2018-02-01

In automated driving, a driver can completely concentrate on non-driving-related tasks (NDRTs). This study investigated the flow experience of a driver who concentrated on NDRTs and tasks that induce mental workload under conditional automation. Participants performed NDRTs under different demand levels: a balanced demand-skill level (fit condition) to induce flow, low-demand level to induce boredom, and high-demand level to induce anxiety. In addition, they performed the additional N-Back task, which artificially induces mental workload. The results showed participants had the longest reaction time when they indicated the highest flow score, and had the longest gaze-on time, road-fixation time, hands-on time, and take-over time under the fit condition. Significant differences were not observed in the driver reaction times in the fit condition and the additional N-Back task, indicating that performing NDRTs that induce a high flow experience could influence driver reaction time similar to performing tasks with a high mental workload. Copyright © 2017. Published by Elsevier Ltd.

Deficits in comprehension of speech acts after TBI: The role of theory of mind and executive function.

PubMed

Honan, Cynthia A; McDonald, Skye; Gowland, Alison; Fisher, Alana; Randall, Rebekah K

2015-11-01

Theory of mind (ToM) is critical to effective communication following traumatic brain injury (TBI) however, whether impairments are specific to social cognition, or reflective of executive demands is unclear. This study examined whether ToM impairments are predicted by executive function difficulties using everyday conversation tasks. Twenty-five individuals with severe-TBI were compared to 25 healthy controls on low- and high-ToM tasks across four conditions: (1) low cognitive load, (2) high flexibility, (3) high working memory (WM) and (4) high inhibition. TBI individuals were impaired on high-ToM tasks in the WM condition. When the WM demands of the task were controlled, the impairments were no longer apparent. TBI individuals were not impaired on high-ToM tasks in the inhibition and flexibility conditions, suggesting these tasks may not have been sufficiently demanding of ToM abilities. The results suggest that ToM impairments in everyday communication may arise due to WM demands, in individuals with TBI. Copyright © 2015 Elsevier Inc. All rights reserved.

A FUNCTIONAL NEUROIMAGING INVESTIGATION OF THE ROLES OF STRUCTURAL COMPLEXITY AND TASK-DEMAND DURING AUDITORY SENTENCE PROCESSING

PubMed Central

Love, Tracy; Haist, Frank; Nicol, Janet; Swinney, David

2009-01-01

Using functional magnetic resonance imaging (fMRI), this study directly examined an issue that bridges the potential language processing and multi-modal views of the role of Broca’s area: the effects of task-demands in language comprehension studies. We presented syntactically simple and complex sentences for auditory comprehension under three different (differentially complex) task-demand conditions: passive listening, probe verification, and theme judgment. Contrary to many language imaging findings, we found that both simple and complex syntactic structures activated left inferior frontal cortex (L-IFC). Critically, we found activation in these frontal regions increased together with increased task-demands. Specifically, tasks that required greater manipulation and comparison of linguistic material recruited L-IFC more strongly; independent of syntactic structure complexity. We argue that much of the presumed syntactic effects previously found in sentence imaging studies of L-IFC may, among other things, reflect the tasks employed in these studies and that L-IFC is a region underlying mnemonic and other integrative functions, on which much language processing may rely. PMID:16881268

Channelized relevance vector machine as a numerical observer for cardiac perfusion defect detection task

NASA Astrophysics Data System (ADS)

Kalayeh, Mahdi M.; Marin, Thibault; Pretorius, P. Hendrik; Wernick, Miles N.; Yang, Yongyi; Brankov, Jovan G.

2011-03-01

In this paper, we present a numerical observer for image quality assessment, aiming to predict human observer accuracy in a cardiac perfusion defect detection task for single-photon emission computed tomography (SPECT). In medical imaging, image quality should be assessed by evaluating the human observer accuracy for a specific diagnostic task. This approach is known as task-based assessment. Such evaluations are important for optimizing and testing imaging devices and algorithms. Unfortunately, human observer studies with expert readers are costly and time-demanding. To address this problem, numerical observers have been developed as a surrogate for human readers to predict human diagnostic performance. The channelized Hotelling observer (CHO) with internal noise model has been found to predict human performance well in some situations, but does not always generalize well to unseen data. We have argued in the past that finding a model to predict human observers could be viewed as a machine learning problem. Following this approach, in this paper we propose a channelized relevance vector machine (CRVM) to predict human diagnostic scores in a detection task. We have previously used channelized support vector machines (CSVM) to predict human scores and have shown that this approach offers better and more robust predictions than the classical CHO method. The comparison of the proposed CRVM with our previously introduced CSVM method suggests that CRVM can achieve similar generalization accuracy, while dramatically reducing model complexity and computation time.

Is set shifting really impaired in trait anxiety? Only when switching away from an effortfully established task set.

PubMed

Gustavson, Daniel E; Altamirano, Lee J; Johnson, Daniel P; Whisman, Mark A; Miyake, Akira

2017-02-01

The current study investigated whether trait anxiety was systematically related to task-set shifting performance, using a task-switching paradigm in which 1 task was more attentionally demanding than the other. Specifically, taking advantage of a well-established phenomenon known as asymmetric switch costs, we tested the hypothesis that the association between trait anxiety and task-set shifting is most clearly observed when individuals must switch away from a more attentionally demanding task for which it was necessary to effortfully establish an appropriate task set. Ninety-one young adults completed an asymmetric switching task and trait-level mood questionnaires. Results indicated that higher levels of trait anxiety were systematically associated with greater asymmetry in reaction time (RT) switch costs. Specifically, the RT costs for switching from the more attentionally demanding task to the less demanding task were significantly greater with higher levels of trait anxiety, whereas the RT costs for switching in the opposite direction were not significantly associated with trait anxiety levels. Further analyses indicated that these associations were not attributable to comorbid dysphoria or worry. These results suggest that levels of trait anxiety may not be related to general set-shifting ability per se, but, rather, that anxiety-specific effects may primarily be restricted to when one must efficiently switch away from (or let go of) an effortfully established task set. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Secure Scientific Applications Scheduling Technique for Cloud Computing Environment Using Global League Championship Algorithm

PubMed Central

Abdulhamid, Shafi’i Muhammad; Abd Latiff, Muhammad Shafie; Abdul-Salaam, Gaddafi; Hussain Madni, Syed Hamid

2016-01-01

Cloud computing system is a huge cluster of interconnected servers residing in a datacenter and dynamically provisioned to clients on-demand via a front-end interface. Scientific applications scheduling in the cloud computing environment is identified as NP-hard problem due to the dynamic nature of heterogeneous resources. Recently, a number of metaheuristics optimization schemes have been applied to address the challenges of applications scheduling in the cloud system, without much emphasis on the issue of secure global scheduling. In this paper, scientific applications scheduling techniques using the Global League Championship Algorithm (GBLCA) optimization technique is first presented for global task scheduling in the cloud environment. The experiment is carried out using CloudSim simulator. The experimental results show that, the proposed GBLCA technique produced remarkable performance improvement rate on the makespan that ranges between 14.44% to 46.41%. It also shows significant reduction in the time taken to securely schedule applications as parametrically measured in terms of the response time. In view of the experimental results, the proposed technique provides better-quality scheduling solution that is suitable for scientific applications task execution in the Cloud Computing environment than the MinMin, MaxMin, Genetic Algorithm (GA) and Ant Colony Optimization (ACO) scheduling techniques. PMID:27384239

Secure Scientific Applications Scheduling Technique for Cloud Computing Environment Using Global League Championship Algorithm.

PubMed

Abdulhamid, Shafi'i Muhammad; Abd Latiff, Muhammad Shafie; Abdul-Salaam, Gaddafi; Hussain Madni, Syed Hamid

2016-01-01

Cloud computing system is a huge cluster of interconnected servers residing in a datacenter and dynamically provisioned to clients on-demand via a front-end interface. Scientific applications scheduling in the cloud computing environment is identified as NP-hard problem due to the dynamic nature of heterogeneous resources. Recently, a number of metaheuristics optimization schemes have been applied to address the challenges of applications scheduling in the cloud system, without much emphasis on the issue of secure global scheduling. In this paper, scientific applications scheduling techniques using the Global League Championship Algorithm (GBLCA) optimization technique is first presented for global task scheduling in the cloud environment. The experiment is carried out using CloudSim simulator. The experimental results show that, the proposed GBLCA technique produced remarkable performance improvement rate on the makespan that ranges between 14.44% to 46.41%. It also shows significant reduction in the time taken to securely schedule applications as parametrically measured in terms of the response time. In view of the experimental results, the proposed technique provides better-quality scheduling solution that is suitable for scientific applications task execution in the Cloud Computing environment than the MinMin, MaxMin, Genetic Algorithm (GA) and Ant Colony Optimization (ACO) scheduling techniques.

An initial framework for the language of higher-order thinking mathematics practices

NASA Astrophysics Data System (ADS)

Staples, Megan E.; Truxaw, Mary P.

2012-09-01

This article presents an examination of the language demands of cognitively demanding tasks and proposes an initial framework for the language demands of higher-order mathematics thinking practices. We articulate four categories for this framework: language of generalisation, language of comparison, language of proportional reasoning, and language of analysing impact. These categories were developed out of our collaborative work to design and implement higher-order thinking tasks with a group of Grade 9 (14- and 15-year-olds) teachers teaching in a linguistically diverse setting; analyses of student work samples on these tasks; and our knowledge of the literature. We describe each type of language demand and then analyse student work in each category to reveal linguistic challenges facing students as they engage these mathematical tasks. Implications for teaching and professional development are discussed.

Enhancing perceptual and attentional skills requires common demands between the action video games and transfer tasks.

PubMed

Oei, Adam C; Patterson, Michael D

2015-01-01

Despite increasing evidence that shows action video game play improves perceptual and cognitive skills, the mechanisms of transfer are not well-understood. In line with previous work, we suggest that transfer is dependent upon common demands between the game and transfer task. In the current study, participants played one of four action games with varying speed, visual, and attentional demands for 20 h. We examined whether training enhanced performance for attentional blink, selective attention, attending to multiple items, visual search and auditory detection. Non-gamers who played the game (Modern Combat) with the highest demands showed transfer to tasks of attentional blink and attending to multiple items. The game (MGS Touch) with fewer attentional demands also decreased attentional blink, but to a lesser degree. Other games failed to show transfer, despite having many action game characteristics but at a reduced intensity. The results support the common demands hypothesis.

Enhancing perceptual and attentional skills requires common demands between the action video games and transfer tasks

PubMed Central

Oei, Adam C.; Patterson, Michael D.

2015-01-01

Despite increasing evidence that shows action video game play improves perceptual and cognitive skills, the mechanisms of transfer are not well-understood. In line with previous work, we suggest that transfer is dependent upon common demands between the game and transfer task. In the current study, participants played one of four action games with varying speed, visual, and attentional demands for 20 h. We examined whether training enhanced performance for attentional blink, selective attention, attending to multiple items, visual search and auditory detection. Non-gamers who played the game (Modern Combat) with the highest demands showed transfer to tasks of attentional blink and attending to multiple items. The game (MGS Touch) with fewer attentional demands also decreased attentional blink, but to a lesser degree. Other games failed to show transfer, despite having many action game characteristics but at a reduced intensity. The results support the common demands hypothesis. PMID:25713551

Parallel photonic information processing at gigabyte per second data rates using transient states

NASA Astrophysics Data System (ADS)

Brunner, Daniel; Soriano, Miguel C.; Mirasso, Claudio R.; Fischer, Ingo

2013-01-01

The increasing demands on information processing require novel computational concepts and true parallelism. Nevertheless, hardware realizations of unconventional computing approaches never exceeded a marginal existence. While the application of optics in super-computing receives reawakened interest, new concepts, partly neuro-inspired, are being considered and developed. Here we experimentally demonstrate the potential of a simple photonic architecture to process information at unprecedented data rates, implementing a learning-based approach. A semiconductor laser subject to delayed self-feedback and optical data injection is employed to solve computationally hard tasks. We demonstrate simultaneous spoken digit and speaker recognition and chaotic time-series prediction at data rates beyond 1Gbyte/s. We identify all digits with very low classification errors and perform chaotic time-series prediction with 10% error. Our approach bridges the areas of photonic information processing, cognitive and information science.

Performing a global barrier operation in a parallel computer

DOEpatents

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2014-12-09

Executing computing tasks on a parallel computer that includes compute nodes coupled for data communications, where each compute node executes tasks, with one task on each compute node designated as a master task, including: for each task on each compute node until all master tasks have joined a global barrier: determining whether the task is a master task; if the task is not a master task, joining a single local barrier; if the task is a master task, joining the global barrier and the single local barrier only after all other tasks on the compute node have joined the single local barrier.

Transfer-appropriate processing in recognition memory: perceptual and conceptual effects on recognition memory depend on task demands.

PubMed

Parks, Colleen M

2013-07-01

Research examining the importance of surface-level information to familiarity in recognition memory tasks is mixed: Sometimes it affects recognition and sometimes it does not. One potential explanation of the inconsistent findings comes from the ideas of dual process theory of recognition and the transfer-appropriate processing framework, which suggest that the extent to which perceptual fluency matters on a recognition test depends in large part on the task demands. A test that recruits perceptual processing for discrimination should show greater perceptual effects and smaller conceptual effects than standard recognition, similar to the pattern of effects found in perceptual implicit memory tasks. This idea was tested in the current experiment by crossing a levels of processing manipulation with a modality manipulation on a series of recognition tests that ranged from conceptual (standard recognition) to very perceptually demanding (a speeded recognition test with degraded stimuli). Results showed that the levels of processing effect decreased and the effect of modality increased when tests were made perceptually demanding. These results support the idea that surface-level features influence performance on recognition tests when they are made salient by the task demands. PsycINFO Database Record (c) 2013 APA, all rights reserved.

An analysis of context-based similarity tasks in textbooks from Brazil and the United States

NASA Astrophysics Data System (ADS)

Barcelos Amaral, Rúbia; Hollebrands, Karen

2017-11-01

Three textbooks from Brazil and three textbooks from the United States were analysed with a focus on similarity and context-based tasks. Students' opportunities to learn similarity were examined by considering whether students were provided context-based tasks of high cognitive demand and whether those tasks included missing or superfluous information. Although books in the United States included more tasks, the proportion of tasks focused on similarity were about the same. Context-based similarity tasks accounted for 9%-29% of the similarity tasks, and many of these contextual tasks were of low cognitive demand. In addition, the types of contexts that were included in the textbooks were critiqued and examples provided.

The Human Physiome: how standards, software and innovative service infrastructures are providing the building blocks to make it achievable

PubMed Central

2016-01-01

Reconstructing and understanding the Human Physiome virtually is a complex mathematical problem, and a highly demanding computational challenge. Mathematical models spanning from the molecular level through to whole populations of individuals must be integrated, then personalized. This requires interoperability with multiple disparate and geographically separated data sources, and myriad computational software tools. Extracting and producing knowledge from such sources, even when the databases and software are readily available, is a challenging task. Despite the difficulties, researchers must frequently perform these tasks so that available knowledge can be continually integrated into the common framework required to realize the Human Physiome. Software and infrastructures that support the communities that generate these, together with their underlying standards to format, describe and interlink the corresponding data and computer models, are pivotal to the Human Physiome being realized. They provide the foundations for integrating, exchanging and re-using data and models efficiently, and correctly, while also supporting the dissemination of growing knowledge in these forms. In this paper, we explore the standards, software tooling, repositories and infrastructures that support this work, and detail what makes them vital to realizing the Human Physiome. PMID:27051515

The Human Physiome: how standards, software and innovative service infrastructures are providing the building blocks to make it achievable.

PubMed

Nickerson, David; Atalag, Koray; de Bono, Bernard; Geiger, Jörg; Goble, Carole; Hollmann, Susanne; Lonien, Joachim; Müller, Wolfgang; Regierer, Babette; Stanford, Natalie J; Golebiewski, Martin; Hunter, Peter

2016-04-06

Reconstructing and understanding the Human Physiome virtually is a complex mathematical problem, and a highly demanding computational challenge. Mathematical models spanning from the molecular level through to whole populations of individuals must be integrated, then personalized. This requires interoperability with multiple disparate and geographically separated data sources, and myriad computational software tools. Extracting and producing knowledge from such sources, even when the databases and software are readily available, is a challenging task. Despite the difficulties, researchers must frequently perform these tasks so that available knowledge can be continually integrated into the common framework required to realize the Human Physiome. Software and infrastructures that support the communities that generate these, together with their underlying standards to format, describe and interlink the corresponding data and computer models, are pivotal to the Human Physiome being realized. They provide the foundations for integrating, exchanging and re-using data and models efficiently, and correctly, while also supporting the dissemination of growing knowledge in these forms. In this paper, we explore the standards, software tooling, repositories and infrastructures that support this work, and detail what makes them vital to realizing the Human Physiome.

Intelligent Context-Aware and Adaptive Interface for Mobile LBS

PubMed Central

Liu, Yanhong

2015-01-01

Context-aware user interface plays an important role in many human-computer Interaction tasks of location based services. Although spatial models for context-aware systems have been studied extensively, how to locate specific spatial information for users is still not well resolved, which is important in the mobile environment where location based services users are impeded by device limitations. Better context-aware human-computer interaction models of mobile location based services are needed not just to predict performance outcomes, such as whether people will be able to find the information needed to complete a human-computer interaction task, but to understand human processes that interact in spatial query, which will in turn inform the detailed design of better user interfaces in mobile location based services. In this study, a context-aware adaptive model for mobile location based services interface is proposed, which contains three major sections: purpose, adjustment, and adaptation. Based on this model we try to describe the process of user operation and interface adaptation clearly through the dynamic interaction between users and the interface. Then we show how the model applies users' demands in a complicated environment and suggested the feasibility by the experimental results. PMID:26457077

Research on Key Technologies of Cloud Computing

NASA Astrophysics Data System (ADS)

Zhang, Shufen; Yan, Hongcan; Chen, Xuebin

With the development of multi-core processors, virtualization, distributed storage, broadband Internet and automatic management, a new type of computing mode named cloud computing is produced. It distributes computation task on the resource pool which consists of massive computers, so the application systems can obtain the computing power, the storage space and software service according to its demand. It can concentrate all the computing resources and manage them automatically by the software without intervene. This makes application offers not to annoy for tedious details and more absorbed in his business. It will be advantageous to innovation and reduce cost. It's the ultimate goal of cloud computing to provide calculation, services and applications as a public facility for the public, So that people can use the computer resources just like using water, electricity, gas and telephone. Currently, the understanding of cloud computing is developing and changing constantly, cloud computing still has no unanimous definition. This paper describes three main service forms of cloud computing: SAAS, PAAS, IAAS, compared the definition of cloud computing which is given by Google, Amazon, IBM and other companies, summarized the basic characteristics of cloud computing, and emphasized on the key technologies such as data storage, data management, virtualization and programming model.

Visual Task Demands and the Auditory Mismatch Negativity: An Empirical Study and a Meta-Analysis

PubMed Central

Wiens, Stefan; Szychowska, Malina; Nilsson, Mats E.

2016-01-01

Because the auditory system is particularly useful in monitoring the environment, previous research has examined whether task-irrelevant, auditory distracters are processed even if subjects focus their attention on visual stimuli. This research suggests that attentionally demanding visual tasks decrease the auditory mismatch negativity (MMN) to simultaneously presented auditory distractors. Because a recent behavioral study found that high visual perceptual load decreased detection sensitivity of simultaneous tones, we used a similar task (n = 28) to determine if high visual perceptual load would reduce the auditory MMN. Results suggested that perceptual load did not decrease the MMN. At face value, these nonsignificant findings may suggest that effects of perceptual load on the MMN are smaller than those of other demanding visual tasks. If so, effect sizes should differ systematically between the present and previous studies. We conducted a selective meta-analysis of published studies in which the MMN was derived from the EEG, the visual task demands were continuous and varied between high and low within the same task, and the task-irrelevant tones were presented in a typical oddball paradigm simultaneously with the visual stimuli. Because the meta-analysis suggested that the present (null) findings did not differ systematically from previous findings, the available evidence was combined. Results of this meta-analysis confirmed that demanding visual tasks reduce the MMN to auditory distracters. However, because the meta-analysis was based on small studies and because of the risk for publication biases, future studies should be preregistered with large samples (n > 150) to provide confirmatory evidence for the results of the present meta-analysis. These future studies should also use control conditions that reduce confounding effects of neural adaptation, and use load manipulations that are defined independently from their effects on the MMN. PMID:26741815

Planning and Enacting Mathematical Tasks of High Cognitive Demand in the Primary Classroom

ERIC Educational Resources Information Center

Georgius, Kelly

2013-01-01

This study offers an examination of two primary-grades teachers as they learn to transfer knowledge from professional development into their classrooms. I engaged in planning sessions with each teacher to help plan tasks of high cognitive demand, including anticipating and planning for classroom discourse that would occur around the task. A…

Time and Motion: Measuring the Effects of the Conceptual Demands of Tasks on Second Language Speech Production

ERIC Educational Resources Information Center

Robinson, Peter; Cadierno, Teresa; Shirai, Yasuhiro

2009-01-01

The Cognition Hypothesis (Robinson 2005) claims that pedagogic tasks should be sequenced for learners in an order of increasing cognitive complexity, and that along resource-directing dimensions of task demands increasing effort at conceptualization promotes more complex and grammaticized second language (L2) speech production. This article…

The role of action coordination for prospective memory: Task-interruption demands affect intention realization.

PubMed

Rummel, Jan; Wesslein, Ann-Katrin; Meiser, Thorsten

2017-05-01

Event-based prospective memory (PM) is the ability to remember to perform an intention in response to an environmental cue. Recent microstructure models postulate four distinguishable stages of successful event-based PM fulfillment. That is, (a) the event must be noticed, (b) the intention must be retrieved, (c) the context must be verified, and (d) the intended action must be coordinated with the demands of any currently ongoing task (e.g., Marsh, Hicks, & Watson, 2002b). Whereas the cognitive processes of Stages 1, 2, and 3 have been studied more or less extensively, little is known about the processes of Stage 4 so far. To fill this gap, the authors manipulated the magnitude of response overlap between the ongoing task and the PM task to isolate Stage-4 processes. Results demonstrate that PM performance improves in the presence versus absence of a response overlap, independent of cue saliency (Experiment 1) and of demands from currently ongoing tasks (Experiment 2). Furthermore, working-memory capacity is associated with PM performance, especially when there is little response overlap (Experiments 2 and 3). Finally, PM performance benefits only from strong response overlap, that is, only when the appropriate ongoing-task and PM response keys were identical (Experiment 4). They conclude that coordinating ongoing-task and PM actions puts cognitive demands on the individual which are distinguishable from the demands imposed by cue-detection and intention-retrieval processes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Effects of aging and job demands on cognitive flexibility assessed by task switching.

PubMed

Gajewski, Patrick D; Wild-Wall, Nele; Schapkin, Sergei A; Erdmann, Udo; Freude, Gabriele; Falkenstein, Michael

2010-10-01

In a cross-sectional, electrophysiological study 91 workers of a big car factory performed a series of switch tasks to assess their cognitive control functions. Four groups of workers participated in the study: 23 young and 23 middle aged assembly line employees and 22 young and 23 middle aged employees with flexible job demands like service and maintenance. Participants performed three digit categorisation tasks. In addition to single task blocks, a cue-based (externally guided) and a memory-based (internally guided) task switch block was administered. Compared to young participants, older ones showed the typical RT-decline. No differences between younger and older participants regarding the local switch costs could be detected despite the source of the current task information. In contrast, whereas the groups did not differ in mixing costs in the cued condition, clear performance decrements in the memory-based mixing block were observed in the group of older employees with repetitive work demands. These findings were corroborated by a number of electrophysiological results showing a reduced CNV suggesting an impairment of task specific preparation, an attenuated P3b suggesting reduced working memory capacity and a decreased Ne suggesting deficits in error monitoring in older participants with repetitive job demands. The results are compatible with the assumption that long lasting, unchallenging job demands may induce several neurocognitive impairments which are already evident in the early fifties. Longitudinal studies are needed to confirm this assumption. Copyright © 2010 Elsevier B.V. All rights reserved.

Students' Interpretations of Writing Tasks: A Case Study.

ERIC Educational Resources Information Center

Kirsch, Gesa

1988-01-01

Argues that successful interpretation of writing tasks demands writers' authority, confidence, and knowledge of rhetorical choices, allowing them to take charge of their own writing rather than catering to the imagined demands of a teacher. (RS)

Increased intra-individual reaction time variability in attention-deficit/hyperactivity disorder across response inhibition tasks with different cognitive demands.

PubMed

Vaurio, Rebecca G; Simmonds, Daniel J; Mostofsky, Stewart H

2009-10-01

One of the most consistent findings in children with ADHD is increased moment-to-moment variability in reaction time (RT). The source of increased RT variability can be examined using ex-Gaussian analyses that divide variability into normal and exponential components and Fast Fourier transform (FFT) that allow for detailed examination of the frequency of responses in the exponential distribution. Prior studies of ADHD using these methods have produced variable results, potentially related to differences in task demand. The present study sought to examine the profile of RT variability in ADHD using two Go/No-go tasks with differing levels of cognitive demand. A total of 140 children (57 with ADHD and 83 typically developing controls), ages 8-13 years, completed both a "simple" Go/No-go task and a more "complex" Go/No-go task with increased working memory load. Repeated measures ANOVA of ex-Gaussian functions revealed for both tasks children with ADHD demonstrated increased variability in both the normal/Gaussian (significantly elevated sigma) and the exponential (significantly elevated tau) components. In contrast, FFT analysis of the exponential component revealed a significant task x diagnosis interaction, such that infrequent slow responses in ADHD differed depending on task demand (i.e., for the simple task, increased power in the 0.027-0.074 Hz frequency band; for the complex task, decreased power in the 0.074-0.202 Hz band). The ex-Gaussian findings revealing increased variability in both the normal (sigma) and exponential (tau) components for the ADHD group, suggest that both impaired response preparation and infrequent "lapses in attention" contribute to increased variability in ADHD. FFT analyses reveal that the periodicity of intermittent lapses of attention in ADHD varies with task demand. The findings provide further support for intra-individual variability as a candidate intermediate endophenotype of ADHD.

Effects of Steady-State Noise on Verbal Working Memory in Young Adults

PubMed Central

Alt, Mary; DeDe, Gayle; Olson, Sarah; Shehorn, James

2015-01-01

Purpose We set out to examine the impact of perceptual, linguistic, and capacity demands on performance of verbal working-memory tasks. The Ease of Language Understanding model (Rönnberg et al., 2013) provides a framework for testing the dynamics of these interactions within the auditory-cognitive system. Methods Adult native speakers of English (n = 45) participated in verbal working-memory tasks requiring processing and storage of words involving different linguistic demands (closed/open set). Capacity demand ranged from 2 to 7 words per trial. Participants performed the tasks in quiet and in speech-spectrum-shaped noise. Separate groups of participants were tested at different signal-to-noise ratios. Word-recognition measures were obtained to determine effects of noise on intelligibility. Results Contrary to predictions, steady-state noise did not have an adverse effect on working-memory performance in every situation. Noise negatively influenced performance for the task with high linguistic demand. Of particular importance is the finding that the adverse effects of background noise were not confined to conditions involving declines in recognition. Conclusions Perceptual, linguistic, and cognitive demands can dynamically affect verbal working-memory performance even in a population of healthy young adults. Results suggest that researchers and clinicians need to carefully analyze task demands to understand the independent and combined auditory-cognitive factors governing performance in everyday listening situations. PMID:26384291

Autonomic Nervous System Responses During Perception of Masked Speech may Reflect Constructs other than Subjective Listening Effort

PubMed Central

Francis, Alexander L.; MacPherson, Megan K.; Chandrasekaran, Bharath; Alvar, Ann M.

2016-01-01

Typically, understanding speech seems effortless and automatic. However, a variety of factors may, independently or interactively, make listening more effortful. Physiological measures may help to distinguish between the application of different cognitive mechanisms whose operation is perceived as effortful. In the present study, physiological and behavioral measures associated with task demand were collected along with behavioral measures of performance while participants listened to and repeated sentences. The goal was to measure psychophysiological reactivity associated with three degraded listening conditions, each of which differed in terms of the source of the difficulty (distortion, energetic masking, and informational masking), and therefore were expected to engage different cognitive mechanisms. These conditions were chosen to be matched for overall performance (keywords correct), and were compared to listening to unmasked speech produced by a natural voice. The three degraded conditions were: (1) Unmasked speech produced by a computer speech synthesizer, (2) Speech produced by a natural voice and masked byspeech-shaped noise and (3) Speech produced by a natural voice and masked by two-talker babble. Masked conditions were both presented at a -8 dB signal to noise ratio (SNR), a level shown in previous research to result in comparable levels of performance for these stimuli and maskers. Performance was measured in terms of proportion of key words identified correctly, and task demand or effort was quantified subjectively by self-report. Measures of psychophysiological reactivity included electrodermal (skin conductance) response frequency and amplitude, blood pulse amplitude and pulse rate. Results suggest that the two masked conditions evoked stronger psychophysiological reactivity than did the two unmasked conditions even when behavioral measures of listening performance and listeners’ subjective perception of task demand were comparable across the three degraded conditions. PMID:26973564

Costs of task allocation with local feedback: Effects of colony size and extra workers in social insects and other multi-agent systems.

PubMed

Radeva, Tsvetomira; Dornhaus, Anna; Lynch, Nancy; Nagpal, Radhika; Su, Hsin-Hao

2017-12-01

Adaptive collective systems are common in biology and beyond. Typically, such systems require a task allocation algorithm: a mechanism or rule-set by which individuals select particular roles. Here we study the performance of such task allocation mechanisms measured in terms of the time for individuals to allocate to tasks. We ask: (1) Is task allocation fundamentally difficult, and thus costly? (2) Does the performance of task allocation mechanisms depend on the number of individuals? And (3) what other parameters may affect their efficiency? We use techniques from distributed computing theory to develop a model of a social insect colony, where workers have to be allocated to a set of tasks; however, our model is generalizable to other systems. We show, first, that the ability of workers to quickly assess demand for work in tasks they are not currently engaged in crucially affects whether task allocation is quickly achieved or not. This indicates that in social insect tasks such as thermoregulation, where temperature may provide a global and near instantaneous stimulus to measure the need for cooling, for example, it should be easy to match the number of workers to the need for work. In other tasks, such as nest repair, it may be impossible for workers not directly at the work site to know that this task needs more workers. We argue that this affects whether task allocation mechanisms are under strong selection. Second, we show that colony size does not affect task allocation performance under our assumptions. This implies that when effects of colony size are found, they are not inherent in the process of task allocation itself, but due to processes not modeled here, such as higher variation in task demand for smaller colonies, benefits of specialized workers, or constant overhead costs. Third, we show that the ratio of the number of available workers to the workload crucially affects performance. Thus, workers in excess of those needed to complete all tasks improve task allocation performance. This provides a potential explanation for the phenomenon that social insect colonies commonly contain inactive workers: these may be a 'surplus' set of workers that improves colony function by speeding up optimal allocation of workers to tasks. Overall our study shows how limitations at the individual level can affect group level outcomes, and suggests new hypotheses that can be explored empirically.

Costs of task allocation with local feedback: Effects of colony size and extra workers in social insects and other multi-agent systems

PubMed Central

Dornhaus, Anna; Su, Hsin-Hao

2017-01-01

Adaptive collective systems are common in biology and beyond. Typically, such systems require a task allocation algorithm: a mechanism or rule-set by which individuals select particular roles. Here we study the performance of such task allocation mechanisms measured in terms of the time for individuals to allocate to tasks. We ask: (1) Is task allocation fundamentally difficult, and thus costly? (2) Does the performance of task allocation mechanisms depend on the number of individuals? And (3) what other parameters may affect their efficiency? We use techniques from distributed computing theory to develop a model of a social insect colony, where workers have to be allocated to a set of tasks; however, our model is generalizable to other systems. We show, first, that the ability of workers to quickly assess demand for work in tasks they are not currently engaged in crucially affects whether task allocation is quickly achieved or not. This indicates that in social insect tasks such as thermoregulation, where temperature may provide a global and near instantaneous stimulus to measure the need for cooling, for example, it should be easy to match the number of workers to the need for work. In other tasks, such as nest repair, it may be impossible for workers not directly at the work site to know that this task needs more workers. We argue that this affects whether task allocation mechanisms are under strong selection. Second, we show that colony size does not affect task allocation performance under our assumptions. This implies that when effects of colony size are found, they are not inherent in the process of task allocation itself, but due to processes not modeled here, such as higher variation in task demand for smaller colonies, benefits of specialized workers, or constant overhead costs. Third, we show that the ratio of the number of available workers to the workload crucially affects performance. Thus, workers in excess of those needed to complete all tasks improve task allocation performance. This provides a potential explanation for the phenomenon that social insect colonies commonly contain inactive workers: these may be a ‘surplus’ set of workers that improves colony function by speeding up optimal allocation of workers to tasks. Overall our study shows how limitations at the individual level can affect group level outcomes, and suggests new hypotheses that can be explored empirically. PMID:29240763

Memory-Efficient Analysis of Dense Functional Connectomes.

PubMed

Loewe, Kristian; Donohue, Sarah E; Schoenfeld, Mircea A; Kruse, Rudolf; Borgelt, Christian

2016-01-01

The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software) are compared with regard to their computational efficiency. The matrix implementation based on on-demand computations has very low memory requirements, thus enabling analyses that would be otherwise infeasible to conduct due to insufficient memory. An open source software package containing the created programs is available for download.

Memory-Efficient Analysis of Dense Functional Connectomes

PubMed Central

Loewe, Kristian; Donohue, Sarah E.; Schoenfeld, Mircea A.; Kruse, Rudolf; Borgelt, Christian

2016-01-01

The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software) are compared with regard to their computational efficiency. The matrix implementation based on on-demand computations has very low memory requirements, thus enabling analyses that would be otherwise infeasible to conduct due to insufficient memory. An open source software package containing the created programs is available for download. PMID:27965565

Evidence for selective executive function deficits in ecstasy/polydrug users.

PubMed

Fisk, J E; Montgomery, C

2009-01-01

Previous research has suggested that the separate aspects of executive functioning are differentially affected by ecstasy use. Although the inhibition process appears to be unaffected by ecstasy use, it is unclear whether this is true of heavy users under conditions of high demand. Tasks loading on the updating process have been shown to be adversely affected by ecstasy use. However, it remains unclear whether the deficits observed reflect the executive aspects of the tasks or whether they are domain general in nature affecting both verbal and visuo-spatial updating. Fourteen heavy ecstasy users (mean total lifetime use 1000 tablets), 39 light ecstasy users (mean total lifetime use 150 tablets) and 28 non-users were tested on tasks loading on the inhibition executive process (random letter generation) and the updating component process (letter updating, visuo-spatial updating and computation span). Heavy users were not impaired in random letter generation even under conditions designed to be more demanding. Ecstasy-related deficits were observed on all updating measures and were statistically significant for two of the three measures. Following controls for various aspects of cannabis use, statistically significant ecstasy-related deficits were obtained on all three updating measures. It was concluded that the inhibition process is unaffected by ecstasy use even among heavy users. By way of contrast, the updating process appears to be impaired in ecstasy users with the deficit apparently domain general in nature.

Impact of three task demand factors on simulated unmanned system intelligence, surveillance, and reconnaissance operations.

PubMed

Abich, Julian; Reinerman-Jones, Lauren; Matthews, Gerald

2017-06-01

The present study investigated how three task demand factors influenced performance, subjective workload and stress of novice intelligence, surveillance, and reconnaissance operators within a simulation of an unmanned ground vehicle. Manipulations were task type, dual-tasking and event rate. Participants were required to discriminate human targets within a street scene from a direct video feed (threat detection [TD] task) and detect changes in symbols presented in a map display (change detection [CD] task). Dual-tasking elevated workload and distress, and impaired performance for both tasks. However, with increasing event rate, CD task deteriorated, but TD improved. Thus, standard workload models provide a better guide to evaluating the demands of abstract symbols than to processing realistic human characters. Assessment of stress and workload may be especially important in the design and evaluation of systems in which human character critical signals must be detected in video images. Practitioner Summary: This experiment assessed subjective workload and stress during threat and CD tasks performed alone and in combination. Results indicated an increase in event rate led to significant improvements in performance during TD, but decrements during CD, yet both had associated increases in workload and engagement.

An Examination of the Role of Technological Tools in Relation to the Cognitive Demand of Mathematical Tasks in Secondary Classrooms

ERIC Educational Resources Information Center

Sherman, Milan

2011-01-01

This study investigates the role of digital cognitive technologies in supporting students' mathematical thinking while engaging with instructional tasks. Specifically, the study sought to better understand how the use of technology is related to the cognitive demand of tasks. Data were collected in four secondary mathematics classrooms via…

Exploring the association between working memory and driving performance in Parkinson's disease.

PubMed

Vardaki, Sophia; Devos, Hannes; Beratis, Ion; Yannis, George; Papageorgiou, Sokratis G

2016-05-18

The aim of this study was to explore whether varying levels of operational and tactical driving task demand differentially affect drivers with Parkinson's disease (PD) and control drivers in their sign recall. Study participants aged between 50 and 70 years included a group of drivers with PD (n = 10) and a group of age- and sex-matched control drivers (n = 10). Their performance in a sign recall task was measured using a driving simulator. Drivers in the control group performed better than drivers with PD in a sign recall task, but this trend was not statistically significant (P =.43). In addition, regardless of group membership, subjects' performance differed according to varying levels of task demand. Performance in the sign recall task was more likely to drop with increasing task demand (P =.03). This difference was significant when the variation in task demand was associated with a cognitive task; that is, when drivers were required to apply the instructions from working memory. Although the conclusions drawn from this study are tentative, the evidence presented here is encouraging with regard to the use of a driving simulator to examine isolated cognitive functions underlying driving performance in PD. With an understanding of its limitations, such driving simulation in combination with functional assessment batteries measuring physical, visual, and cognitive abilities could comprise one component of a multitiered system to evaluate medical fitness to drive.

Shared filtering processes link attentional and visual short-term memory capacity limits.

PubMed

Bettencourt, Katherine C; Michalka, Samantha W; Somers, David C

2011-09-30

Both visual attention and visual short-term memory (VSTM) have been shown to have capacity limits of 4 ± 1 objects, driving the hypothesis that they share a visual processing buffer. However, these capacity limitations also show strong individual differences, making the degree to which these capacities are related unclear. Moreover, other research has suggested a distinction between attention and VSTM buffers. To explore the degree to which capacity limitations reflect the use of a shared visual processing buffer, we compared individual subject's capacities on attentional and VSTM tasks completed in the same testing session. We used a multiple object tracking (MOT) and a VSTM change detection task, with varying levels of distractors, to measure capacity. Significant correlations in capacity were not observed between the MOT and VSTM tasks when distractor filtering demands differed between the tasks. Instead, significant correlations were seen when the tasks shared spatial filtering demands. Moreover, these filtering demands impacted capacity similarly in both attention and VSTM tasks. These observations fail to support the view that visual attention and VSTM capacity limits result from a shared buffer but instead highlight the role of the resource demands of underlying processes in limiting capacity.

Contextual cueing of pop-out visual search: when context guides the deployment of attention.

PubMed

Geyer, Thomas; Zehetleitner, Michael; Müller, Hermann J

2010-05-01

Visual context information can guide attention in demanding (i.e., inefficient) search tasks. When participants are repeatedly presented with identically arranged ('repeated') displays, reaction times are faster relative to newly composed ('non-repeated') displays. The present article examines whether this 'contextual cueing' effect operates also in simple (i.e., efficient) search tasks and if so, whether there it influences target, rather than response, selection. The results were that singleton-feature targets were detected faster when the search items were presented in repeated, rather than non-repeated, arrangements. Importantly, repeated, relative to novel, displays also led to an increase in signal detection accuracy. Thus, contextual cueing can expedite the selection of pop-out targets, most likely by enhancing feature contrast signals at the overall-salience computation stage.

Initial Development of a Brief Behavioral Economic Assessment of Alcohol Demand

PubMed Central

Owens, Max M.; Murphy, Cara M.; MacKillop, James

2015-01-01

Due to difficulties with definition and measurement, the role of conscious craving in substance use disorders remains contentious. To address this, behavioral economics is increasingly being used to quantify aspects of an individual’s acute motivation to use a substance. Doing so typically involves the use of a purchase task, in which participants make choices about consuming alcohol or other substances at various prices and multiple indices of alcohol demand are generated. However, purchase tasks can be limited by the time required to administer and score them. In the current study, a brief 3-item measure, designed to capture three important indices of demand that are derived from demand curve modeling (intensity, Omax, and breakpoint), was investigated in a group of 84 heavy drinkers. Participants underwent a cue-reactivity paradigm that is established to increase both conscious craving and alcohol demand on traditional purchase tasks. All three indices of demand for alcohol measured using the abbreviated measure increased significantly in response to alcohol cues, analogous to what has been observed using a traditional purchase task. Additionally, the correlations between these indices and subjective craving were modest-to-moderate, as has been found in studies comparing craving to the indices derived from purchase tasks. These findings suggest that this abbreviated measure may be a useful and efficient way to capture important and distinct aspects of motivation for alcohol. If these results are confirmed, this measure may be able to help increase the portability of behavioral economic indices of demand into novel research and clinical contexts. PMID:27135038

U.S. Army Physical Demands Study: Reliability of Simulations of Physically Demanding Tasks Performed by Combat Arms Soldiers.

PubMed

Foulis, Stephen A; Redmond, Jan E; Frykman, Peter N; Warr, Bradley J; Zambraski, Edward J; Sharp, Marilyn A

2017-12-01

Foulis, SA, Redmond, JE, Frykman, PN, Warr, BJ, Zambraski, EJ, and Sharp, MA. U.S. Army physical demands study: reliability of simulations of physically demanding tasks performed by combat arms soldiers. J Strength Cond Res 31(12): 3245-3252, 2017-Recently, the U.S. Army has mandated that soldiers must successfully complete the physically demanding tasks of their job to graduate from their Initial Military Training. Evaluating individual soldiers in the field is difficult; however, simulations of these tasks may aid in the assessment of soldiers' abilities. The purpose of this study was to determine the reliability of simulated physical soldiering tasks relevant to combat arms soldiers. Three cohorts of ∼50 soldiers repeated a subset of 8 simulated tasks 4 times over 2 weeks. Simulations included: sandbag carry, casualty drag, and casualty evacuation from a vehicle turret, move under direct fire, stow ammunition on a tank, load the main gun of a tank, transferring ammunition with a field artillery supply vehicle, and a 4-mile foot march. Reliability was assessed using intraclass correlation coefficients (ICCs), standard errors of measurement (SEMs), and 95% limits of agreement. Performance of the casualty drag and foot march did not improve across trials (p > 0.05), whereas improvements, suggestive of learning effects, were observed on the remaining 6 tasks (p ≤ 0.05). The ICCs ranged from 0.76 to 0.96, and the SEMs ranged from 3 to 16% of the mean. These 8 simulated tasks show high reliability. Given proper practice, they are suitable for evaluating the ability of Combat Arms Soldiers to complete the physical requirements of their jobs.

Attention during active visual tasks: counting, pointing, or simply looking

PubMed Central

Wilder, John D.; Schnitzer, Brian S.; Gersch, Timothy M.; Dosher, Barbara A.

2009-01-01

Visual attention and saccades are typically studied in artificial situations, with stimuli presented to the steadily fixating eye, or saccades made along specified paths. By contrast, in the real world saccadic patterns are constrained only by the demands of the motivating task. We studied attention during pauses between saccades made to perform 3 free-viewing tasks: counting dots, pointing to the same dots with a visible cursor, or simply looking at the dots using a freely-chosen path. Attention was assessed by the ability to identify the orientation of a briefly-presented Gabor probe. All primary tasks produced losses in identification performance, with counting producing the largest losses, followed by pointing and then looking-only. Looking-only resulted in a 37% increase in contrast thresholds in the orientation task. Counting produced more severe losses that were not overcome by increasing Gabor contrast. Detection or localization of the Gabor, unlike identification, were largely unaffected by any of the primary tasks. Taken together, these results show that attention is required to control saccades, even with freely-chosen paths, but the attentional demands of saccades are less than those attached to tasks such as counting, which have a significant cognitive load. Counting proved to be a highly demanding task that either exhausted momentary processing capacity (e.g., working memory or executive functions), or, alternatively, encouraged a strategy of filtering out all signals irrelevant to counting itself. The fact that the attentional demands of saccades (as well as those of detection/localization) are relatively modest makes it possible to continually adjust both the spatial and temporal pattern of saccades so as to re-allocate attentional resources as needed to handle the complex and multifaceted demands of real-world environments. PMID:18649913

Does the attentional demands of walking differ for older men and women living independently in the community?

PubMed

Wellmon, Robert

2012-01-01

Walking has been shown to be an attentionally demanding task. For older adults, gender-specific differences in gait and falling reported in the literature could arise as a result of the attentional demands of walking. However, differences in how older men and women allocate attention to walking have not been investigated. The purpose of this study was to use a dual-task voice reaction time paradigm to examine gender-specific differences in the attentional demands of walking in older adults who are independent in community ambulation. A dual-task paradigm was used to measure voice reaction time (VRT) in older community-dwelling men (n = 29; mean age = 78.40, SD = 6.17 years) and women (n = 33; mean age = 77.01, SD = 6.07 years) under 3 task conditions: sitting in a chair, standing, and walking on a level surface. Between- and within-group differences in dual-task VRT were examined using a 2 (men vs women) by 3 (task condition) repeated-measures analysis of variance. The level of statistical significance was set at 0.05, and a Bonferroni procedure was used for post hoc analyses. Sitting VRT was similar for men (mean = 454.90, SD = 140.05 milliseconds) and women (mean = 454.49, SD = 94.27 milliseconds). While standing, men had a slightly faster VRT (mean = 444.90, SD = 125.31 milliseconds vs mean = 452.09, SD = 92.82 milliseconds). When walking, VRT increased for both groups in comparison to sitting and standing and older men (mean = 509.11, SD = 142.19 milliseconds) responded faster than older women (mean = 537.55, SD = 122.43). However, the main effect of gender (P = .665) and interaction of gender with task (P = .433) were both not statistically significant. A statistically significant main effect for task (P < .001) indicated that walking VRT (mean = 524.25, SD = 131.71 milliseconds) was significantly longer than both sitting (P < .001, mean = 454.68, SD = 116.89 milliseconds) and standing (P < .001, mean = 448.36, SD = 108.37 milliseconds) VRT. The results demonstrate that the attentional demands of walking are not different for older adult men and women who are independent in community mobility. However, support was provided for the idea that walking is an attentionally demanding activity. In comparison with sitting and standing, walking was more attentionally demanding for both men and women. CONCLUSIONS.: A dual-task voice reaction time paradigm revealed that walking is not more attentionally demanding on the basis of gender when comparing community-dwelling older adult men with women.

Consistent Performance Differences between Children and Adults Despite Manipulation of Cue-Target Variables

PubMed Central

Bauer, Jessie-Raye; Martinez, Joel E.; Roe, Mary Abbe; Church, Jessica A.

2017-01-01

Two behavioral experiments assessed the plasticity and short-term improvement of task switching in 215 children and adults. Specifically, we studied manipulations of cued attention to different features of a target stimulus as a way to assess the development of cognitive flexibility. Each experiment had multiple levels of difficulty via manipulation of number of cued features (2–4) and number of response options (2 or 4). Working memory demand was manipulated across the two experiments. Impact of memory demand and task level manipulations on task accuracy and response times were measured. There were three overall goals: First, these task manipulations (number of cued features, response choices, and working memory load) were tested to assess the stability of group differences in performance between children ages 6–16 years and adults 18–27 years, with the goal of reducing age group differences. Second, age-related transitions to adult-level performance were examined within subgroups of the child sample. Third, short-term improvement from the beginning to the end of the study session was measured to probe whether children can improve with task experience. Attempts to use task manipulations to reduce age differences in cued task switching performance were unsuccessful: children performed consistently worse and were more susceptible to task manipulations than adults. However, across both studies, adult-like performance was observed around mid-adolescence, by ages 13-16 years. Certain task manipulations, especially increasing number of response options when working memory demand was low, produced differences from adults even in the oldest children. Interestingly, there was similar performance improvement with practice for both child and adult groups. The higher memory demand version of the task (Experiment 2) prompted greater short-term improvement in accuracy and response times than the lower memory demand version (Experiment 1). These results reveal stable differences in cued switching performance over development, but also relative flexibility within a given individual over time. PMID:28824489

Task demands and the pressures of everyday life: associations between cardiovascular reactivity and work blood pressure and heart rate.

PubMed

Steptoe, A; Cropley, M; Joekes, K

2000-01-01

Associations between cardiovascular stress reactivity and blood pressure and heart rate recorded in everyday life were hypothesized to depend on the stressfulness of the ambulatory monitoring period relative to standardized tasks and on activity levels at the time of measurement. One hundred two female and 60 male school teachers carried out high- and low-demand tasks under standardized conditions and ambulatory monitoring during the working day. Stress ratings during the day were close to those recorded during the low-demand task. Reactions to the low-demand task were significant predictors of ambulatory blood pressure and heart rate independent of baseline, age, gender, and body mass. Associations were more consistent for ambulatory recordings taken when participants were seated than when they were standing and when the ambulatory monitoring day was considered to be as stressful as usual or more stressful than usual, and not less stressful than usual. Laboratory-field associations of cardiovascular activity depend in part on the congruence of stressfulness and physical activity level in the 2 situations.

Computer-aided detection systems to improve lung cancer early diagnosis: state-of-the-art and challenges

NASA Astrophysics Data System (ADS)

Traverso, A.; Lopez Torres, E.; Fantacci, M. E.; Cerello, P.

2017-05-01

Lung cancer is one of the most lethal types of cancer, because its early diagnosis is not good enough. In fact, the detection of pulmonary nodule, potential lung cancers, in Computed Tomography scans is a very challenging and time-consuming task for radiologists. To support radiologists, researchers have developed Computer-Aided Diagnosis (CAD) systems for the automated detection of pulmonary nodules in chest Computed Tomography scans. Despite the high level of technological developments and the proved benefits on the overall detection performance, the usage of Computer-Aided Diagnosis in clinical practice is far from being a common procedure. In this paper we investigate the causes underlying this discrepancy and present a solution to tackle it: the M5L WEB- and Cloud-based on-demand Computer-Aided Diagnosis. In addition, we prove how the combination of traditional imaging processing techniques with state-of-art advanced classification algorithms allows to build a system whose performance could be much larger than any Computer-Aided Diagnosis developed so far. This outcome opens the possibility to use the CAD as clinical decision support for radiologists.

BCM: toolkit for Bayesian analysis of Computational Models using samplers.

PubMed

Thijssen, Bram; Dijkstra, Tjeerd M H; Heskes, Tom; Wessels, Lodewyk F A

2016-10-21

Computational models in biology are characterized by a large degree of uncertainty. This uncertainty can be analyzed with Bayesian statistics, however, the sampling algorithms that are frequently used for calculating Bayesian statistical estimates are computationally demanding, and each algorithm has unique advantages and disadvantages. It is typically unclear, before starting an analysis, which algorithm will perform well on a given computational model. We present BCM, a toolkit for the Bayesian analysis of Computational Models using samplers. It provides efficient, multithreaded implementations of eleven algorithms for sampling from posterior probability distributions and for calculating marginal likelihoods. BCM includes tools to simplify the process of model specification and scripts for visualizing the results. The flexible architecture allows it to be used on diverse types of biological computational models. In an example inference task using a model of the cell cycle based on ordinary differential equations, BCM is significantly more efficient than existing software packages, allowing more challenging inference problems to be solved. BCM represents an efficient one-stop-shop for computational modelers wishing to use sampler-based Bayesian statistics.

Technology implications of a cognitive task analysis for locomotive engineers

DOT National Transportation Integrated Search

2009-01-01

This report documents the results of a cognitive task analysis (CTA) that examined the cognitive demands and activities of locomotive engineers in todays environment and the changes in cognitive demands and activities that are likely to arise with...

Toward cognitive pipelines of medical assistance algorithms.

PubMed

Philipp, Patrick; Maleshkova, Maria; Katic, Darko; Weber, Christian; Götz, Michael; Rettinger, Achim; Speidel, Stefanie; Kämpgen, Benedikt; Nolden, Marco; Wekerle, Anna-Laura; Dillmann, Rüdiger; Kenngott, Hannes; Müller, Beat; Studer, Rudi

2016-09-01

Assistance algorithms for medical tasks have great potential to support physicians with their daily work. However, medicine is also one of the most demanding domains for computer-based support systems, since medical assistance tasks are complex and the practical experience of the physician is crucial. Recent developments in the area of cognitive computing appear to be well suited to tackle medicine as an application domain. We propose a system based on the idea of cognitive computing and consisting of auto-configurable medical assistance algorithms and their self-adapting combination. The system enables automatic execution of new algorithms, given they are made available as Medical Cognitive Apps and are registered in a central semantic repository. Learning components can be added to the system to optimize the results in the cases when numerous Medical Cognitive Apps are available for the same task. Our prototypical implementation is applied to the areas of surgical phase recognition based on sensor data and image progressing for tumor progression mappings. Our results suggest that such assistance algorithms can be automatically configured in execution pipelines, candidate results can be automatically scored and combined, and the system can learn from experience. Furthermore, our evaluation shows that the Medical Cognitive Apps are providing the correct results as they did for local execution and run in a reasonable amount of time. The proposed solution is applicable to a variety of medical use cases and effectively supports the automated and self-adaptive configuration of cognitive pipelines based on medical interpretation algorithms.

Time and number of displays impact critical signal detection in fetal heart rate tracings.

PubMed

Anderson, Brittany L; Scerbo, Mark W; Belfore, Lee A; Abuhamad, Alfred Z

2011-06-01

Interest in centralized monitoring in labor and delivery units is growing because it affords the opportunity to monitor multiple patients simultaneously. However, a long history of research on sustained attention reveals these types of monitoring tasks can be problematic. The goal of the present experiment was to examine the ability of individuals to detect critical signals in fetal heart rate (FHR) tracings in one or more displays over an extended period of time. Seventy-two participants monitored one, two, or four computer-simulated FHR tracings on a computer display for the appearance of late decelerations over a 48-minute vigil. Measures of subjective stress and workload were also obtained before and after the vigil. The results showed that detection accuracy decreased over time and also declined as the number of displays increased. The subjective reports indicated that participants found the task to be stressful and mentally demanding, effortful, and frustrating. The results suggest that centralized monitoring that allows many patients to be monitored simultaneously may impose a detrimental attentional burden on the observer. Furthermore, this seemingly benign task may impose an additional source of stress and mental workload above what is commonly found in labor and delivery units. © Thieme Medical Publishers.

Investigations of rhesus monkey video-task performance: evidence for enrichment

NASA Technical Reports Server (NTRS)

Washburn, D. A.; Rumbaugh, D. M.

1992-01-01

We have developed the Language Research Center's Computerized Test System (LRC-CTS) for psychological research. Basically, the LRC-CTS is a battery of software tasks--computerized versions of many of the classic testing paradigms of cognitive and comparative psychology--and the hardware required to administer them. An XT- or 386-compatible computer is connected to a color monitor, onto which computer-generated stimuli are presented. Sound feedback is delivered through an external speaker/amplifier, and a joystick is used as an input device. The animals reach through the mesh of their home cages to manipulate the joystick, which causes isomorphic movements of a cursor on the screen thereby allowing animals to respond according to the varied demands of the tasks. Correct responses are rewarded with a fruit-flavored chow pellet. Using this technology, we have trained and tested rhesus monkeys, a variety of apes, human adults, and normally developing or mentally retarded human children. Other labs using the LRC-CTS are beginning to report encouraging results with other monkey species as well. From this research, a number of interesting and important psychological findings have resulted. In the present paper, however, evidence will be reviewed which suggests that the LRC-CTS is an effective means of providing environmental enrichment to singly housed rhesus monkeys.

Regulatory focus moderates the relationship between task control and physiological and psychological markers of stress: a work simulation study.

PubMed

Parker, Stacey L; Laurie, Kaitlan R; Newton, Cameron J; Jimmieson, Nerina L

2014-12-01

This experiment examined whether trait regulatory focus moderates the effects of task control on stress reactions during a demanding work simulation. Regulatory focus describes two ways in which individuals self-regulate toward desired goals: promotion and prevention. As highly promotion-focused individuals are oriented toward growth and challenge, it was expected that they would show better adaptation to demanding work under high task control. In contrast, as highly prevention-focused individuals are oriented toward safety and responsibility they were expected to show better adaptation under low task control. Participants (N=110) completed a measure of trait regulatory focus and then three trials of a demanding inbox activity under either low, neutral, or high task control. Heart rate variability (HRV), affective reactions (anxiety & task dissatisfaction), and task performance were measured at each trial. As predicted, highly promotion-focused individuals found high (compared to neutral) task control stress-buffering for performance. Moreover, highly prevention-focused individuals found high (compared to low) task control stress-exacerbating for dissatisfaction. In addition, highly prevention-focused individuals found low task control stress-buffering for dissatisfaction, performance, and HRV. However, these effects of low task control for highly prevention-focused individuals depended on their promotion focus. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Academic Task Demand in the 21st-Century, High-Stakes-Accountability School: Mapping the Journey from Poor [To Fair to Good to Great] to Excellent?

ERIC Educational Resources Information Center

Szczesiul, Stacy Agee; Nehring, James; Carey, Theodore

2015-01-01

Drawing on theoretical and empirical research concerning the relationship between academic work and student learning, this article explores the following questions: What skills are required to execute the academic tasks teachers assign on a daily basis? How do teachers and administrators interpret the task demands represented in instructional…

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Performing a global barrier operation in a parallel computer that includes compute nodes coupled for data communications, where each compute node executes tasks, with one task on each compute node designated as a master task, including: for each task on each compute node until all master tasks have joined a global barrier: determining whether the task is a master task; if the task is not a master task, joining a single local barrier; if the task is a master task, joining the global barrier and the single local barrier only after all other tasks on the compute node have joinedmore » the single local barrier.« less

Estimating demand for alternatives to cigarettes with online purchase tasks.

PubMed

O'Connor, Richard J; June, Kristie M; Bansal-Travers, Maansi; Rousu, Matthew C; Thrasher, James F; Hyland, Andrew; Cummings, K Michael

2014-01-01

To explore how advertising affects demand for cigarettes and potential substitutes, including snus, dissolvable tobacco, and medicinal nicotine. A Web-based experiment randomized 1062 smokers to see advertisements for alternative nicotine products or soft drinks, then complete a series of purchase tasks, which were used to estimate demand elasticity, peak consumption, and cross-price elasticity (CPE) for tobacco products. Lower demand elasticity and greater peak consumption were seen for cigarettes compared to all alternative products (p < .05). CPE did not differ across the alternative products (p ≤ .03). Seeing relevant advertisements was not significantly related to demand. These findings suggest significantly lower demand for alternative nicotine sources among smokers than previously revealed.

Cognitive control over learning: Creating, clustering and generalizing task-set structure

PubMed Central

Collins, Anne G.E.; Frank, Michael J.

2013-01-01

Executive functions and learning share common neural substrates essential for their expression, notably in prefrontal cortex and basal ganglia. Understanding how they interact requires studying how cognitive control facilitates learning, but also how learning provides the (potentially hidden) structure, such as abstract rules or task-sets, needed for cognitive control. We investigate this question from three complementary angles. First, we develop a new computational “C-TS” (context-task-set) model inspired by non-parametric Bayesian methods, specifying how the learner might infer hidden structure and decide whether to re-use that structure in new situations, or to create new structure. Second, we develop a neurobiologically explicit model to assess potential mechanisms of such interactive structured learning in multiple circuits linking frontal cortex and basal ganglia. We systematically explore the link betweens these levels of modeling across multiple task demands. We find that the network provides an approximate implementation of high level C-TS computations, where manipulations of specific neural mechanisms are well captured by variations in distinct C-TS parameters. Third, this synergism across models yields strong predictions about the nature of human optimal and suboptimal choices and response times during learning. In particular, the models suggest that participants spontaneously build task-set structure into a learning problem when not cued to do so, which predicts positive and negative transfer in subsequent generalization tests. We provide evidence for these predictions in two experiments and show that the C-TS model provides a good quantitative fit to human sequences of choices in this task. These findings implicate a strong tendency to interactively engage cognitive control and learning, resulting in structured abstract representations that afford generalization opportunities, and thus potentially long-term rather than short-term optimality. PMID:23356780

Implementing Kanban for agile process management within the ALMA Software Operations Group

NASA Astrophysics Data System (ADS)

Reveco, Johnny; Mora, Matias; Shen, Tzu-Chiang; Soto, Ruben; Sepulveda, Jorge; Ibsen, Jorge

2014-07-01

After the inauguration of the Atacama Large Millimeter/submillimeter Array (ALMA), the Software Operations Group in Chile has refocused its objectives to: (1) providing software support to tasks related to System Integration, Scientific Commissioning and Verification, as well as Early Science observations; (2) testing the remaining software features, still under development by the Integrated Computing Team across the world; and (3) designing and developing processes to optimize and increase the level of automation of operational tasks. Due to their different stakeholders, each of these tasks presents a wide diversity of importances, lifespans and complexities. Aiming to provide the proper priority and traceability for every task without stressing our engineers, we introduced the Kanban methodology in our processes in order to balance the demand on the team against the throughput of the delivered work. The aim of this paper is to share experiences gained during the implementation of Kanban in our processes, describing the difficulties we have found, solutions and adaptations that led us to our current but still evolving implementation, which has greatly improved our throughput, prioritization and problem traceability.

Using multiple sensors for printed circuit board insertion

NASA Technical Reports Server (NTRS)

Sood, Deepak; Repko, Michael C.; Kelley, Robert B.

1989-01-01

As more and more activities are performed in space, there will be a greater demand placed on the information handling capacity of people who are to direct and accomplish these tasks. A promising alternative to full-time human involvement is the use of semi-autonomous, intelligent robot systems. To automate tasks such as assembly, disassembly, repair and maintenance, the issues presented by environmental uncertainties need to be addressed. These uncertainties are introduced by variations in the computed position of the robot at different locations in its work envelope, variations in part positioning, and tolerances of part dimensions. As a result, the robot system may not be able to accomplish the desired task without the help of sensor feedback. Measurements on the environment allow real time corrections to be made to the process. A design and implementation of an intelligent robot system which inserts printed circuit boards into a card cage are presented. Intelligent behavior is accomplished by coupling the task execution sequence with information derived from three different sensors: an overhead three-dimensional vision system, a fingertip infrared sensor, and a six degree of freedom wrist-mounted force/torque sensor.

Volunteered Cloud Computing for Disaster Management

NASA Astrophysics Data System (ADS)

Evans, J. D.; Hao, W.; Chettri, S. R.

2014-12-01

Disaster management relies increasingly on interpreting earth observations and running numerical models; which require significant computing capacity - usually on short notice and at irregular intervals. Peak computing demand during event detection, hazard assessment, or incident response may exceed agency budgets; however some of it can be met through volunteered computing, which distributes subtasks to participating computers via the Internet. This approach has enabled large projects in mathematics, basic science, and climate research to harness the slack computing capacity of thousands of desktop computers. This capacity is likely to diminish as desktops give way to battery-powered mobile devices (laptops, smartphones, tablets) in the consumer market; but as cloud computing becomes commonplace, it may offer significant slack capacity -- if its users are given an easy, trustworthy mechanism for participating. Such a "volunteered cloud computing" mechanism would also offer several advantages over traditional volunteered computing: tasks distributed within a cloud have fewer bandwidth limitations; granular billing mechanisms allow small slices of "interstitial" computing at no marginal cost; and virtual storage volumes allow in-depth, reversible machine reconfiguration. Volunteered cloud computing is especially suitable for "embarrassingly parallel" tasks, including ones requiring large data volumes: examples in disaster management include near-real-time image interpretation, pattern / trend detection, or large model ensembles. In the context of a major disaster, we estimate that cloud users (if suitably informed) might volunteer hundreds to thousands of CPU cores across a large provider such as Amazon Web Services. To explore this potential, we are building a volunteered cloud computing platform and targeting it to a disaster management context. Using a lightweight, fault-tolerant network protocol, this platform helps cloud users join parallel computing projects; automates reconfiguration of their virtual machines; ensures accountability for donated computing; and optimizes the use of "interstitial" computing. Initial applications include fire detection from multispectral satellite imagery and flood risk mapping through hydrological simulations.

Motor demand-dependent activation of ipsilateral motor cortex.

PubMed

Buetefisch, Cathrin M; Revill, Kate Pirog; Shuster, Linda; Hines, Benjamin; Parsons, Michael

2014-08-15

The role of ipsilateral primary motor cortex (M1) in hand motor control during complex task performance remains controversial. Bilateral M1 activation is inconsistently observed in functional (f)MRI studies of unilateral hand performance. Two factors limit the interpretation of these data. As the motor tasks differ qualitatively in these studies, it is conceivable that M1 contributions differ with the demand on skillfulness. Second, most studies lack the verification of a strictly unilateral execution of the motor task during the acquisition of imaging data. Here, we use fMRI to determine whether ipsilateral M1 activity depends on the demand for precision in a pointing task where precision varied quantitatively while movement trajectories remained equal. Thirteen healthy participants used an MRI-compatible joystick to point to targets of four different sizes in a block design. A clustered acquisition technique allowed simultaneous fMRI/EMG data collection and confirmed that movements were strictly unilateral. Accuracy of performance increased with target size. Overall, the pointing task revealed activation in contralateral and ipsilateral M1, extending into contralateral somatosensory and parietal areas. Target size-dependent activation differences were found in ipsilateral M1 extending into the temporal/parietal junction, where activation increased with increasing demand on accuracy. The results suggest that ipsilateral M1 is active during the execution of a unilateral motor task and that its activity is modulated by the demand on precision. Copyright © 2014 the American Physiological Society.

Adapting to an initial self-regulatory task cancels the ego depletion effect.

PubMed

Dang, Junhua; Dewitte, Siegfried; Mao, Lihua; Xiao, Shanshan; Shi, Yucai

2013-09-01

The resource-based model of self-regulation provides a pessimistic view of self-regulation that people are destined to lose their self-control after having engaged in any act of self-regulation because these acts deplete the limited resource that people need for successful self-regulation. The cognitive control theory, however, offers an alternative explanation and suggests that the depletion effect reflects switch costs between different cognitive control processes recruited to deal with demanding tasks. This account implies that the depletion effect will not occur once people have had the opportunity to adapt to the self-regulatory task initially engaged in. Consistent with this idea, the present study showed that engaging in a demanding task led to performance deficits on a subsequent self-regulatory task (i.e. the depletion effect) only when the initial demanding task was relatively short but not when it was long enough for participants to adapt. Our results were unrelated to self-efficacy, mood, and motivation. Copyright © 2013 Elsevier Inc. All rights reserved.

How Do Clinical Information Systems Affect the Cognitive Demands of General Practitioners?: Usability Study with a Focus on Cognitive Workload.

PubMed

Ariza, Ferran; Kalra, Dipak; Potts, Henry Ww

2015-11-20

Clinical information systems in the National Health Service do not need to conform to any explicit usability requirements. Poor usability can increase the mental workload experienced by clinicians and cause fatigue, increase error rates and impact the overall patient safety. Mental workload can be used as a measure of usability. To assess the subjective cognitive workload experienced by general practitioners (GPs) with their systems. To raise awareness of the importance of usability in system design among users, designers, developers and policymakers. We used a modified version of the NASA Task Load Index, adapted for web. We developed a set of common clinical scenarios and computer tasks on an online survey. We emailed the study link to 199 clinical commissioning groups and 1,646 GP practices in England. Sixty-seven responders completed the survey. The respondents had spent an average of 17 years in general practice, had experience of using a mean of 1.5 GP computer systems and had used their current system for a mean time of 6.7 years. The mental workload score was not different among systems. There were significant differences among the task scores, but these differences were not specific to particular systems. The overall score and task scores were related to the length of experience with their present system. Four tasks imposed a higher mental workload on GPs: 'repeat prescribing', 'find episode', 'drug management' and 'overview records'. Further usability studies on GP systems should focus on these tasks. Users, policymakers, designers and developers should remain aware of the importance of usability in system design.What does this study add?• Current GP systems in England do not need to conform to explicit usability requirements. Poor usability can increase the mental workload of clinicians and lead to errors.• Some clinical computer tasks incur more cognitive workload than others and should be considered carefully during the design of a system.• GPs did not report overall very high levels of subjective cognitive workload when undertaking common clinical tasks with their systems.• Further usability studies on GP systems should focus on the tasks incurring higher cognitive workload.• Users, policymakers, and designers and developers should remain aware of the importance of usability in system design.

Anterior Cingulate Cortex Instigates Adaptive Switches in Choice by Integrating Immediate and Delayed Components of Value in Ventromedial Prefrontal Cortex

PubMed Central

Guitart-Masip, Marc; Kurth-Nelson, Zeb; Dolan, Raymond J.

2014-01-01

Actions can lead to an immediate reward or punishment and a complex set of delayed outcomes. Adaptive choice necessitates the brain track and integrate both of these potential consequences. Here, we designed a sequential task whereby the decision to exploit or forego an available offer was contingent on comparing immediate value and a state-dependent future cost of expending a limited resource. Crucially, the dynamics of the task demanded frequent switches in policy based on an online computation of changing delayed consequences. We found that human subjects choose on the basis of a near-optimal integration of immediate reward and delayed consequences, with the latter computed in a prefrontal network. Within this network, anterior cingulate cortex (ACC) was dynamically coupled to ventromedial prefrontal cortex (vmPFC) when adaptive switches in choice were required. Our results suggest a choice architecture whereby interactions between ACC and vmPFC underpin an integration of immediate and delayed components of value to support flexible policy switching that accommodates the potential delayed consequences of an action. PMID:24573291

Computer vision for driver assistance systems

NASA Astrophysics Data System (ADS)

Handmann, Uwe; Kalinke, Thomas; Tzomakas, Christos; Werner, Martin; von Seelen, Werner

1998-07-01

Systems for automated image analysis are useful for a variety of tasks and their importance is still increasing due to technological advances and an increase of social acceptance. Especially in the field of driver assistance systems the progress in science has reached a level of high performance. Fully or partly autonomously guided vehicles, particularly for road-based traffic, pose high demands on the development of reliable algorithms due to the conditions imposed by natural environments. At the Institut fur Neuroinformatik, methods for analyzing driving relevant scenes by computer vision are developed in cooperation with several partners from the automobile industry. We introduce a system which extracts the important information from an image taken by a CCD camera installed at the rear view mirror in a car. The approach consists of a sequential and a parallel sensor and information processing. Three main tasks namely the initial segmentation (object detection), the object tracking and the object classification are realized by integration in the sequential branch and by fusion in the parallel branch. The main gain of this approach is given by the integrative coupling of different algorithms providing partly redundant information.

Syntactic structure building in the anterior temporal lobe during natural story listening.

PubMed

Brennan, Jonathan; Nir, Yuval; Hasson, Uri; Malach, Rafael; Heeger, David J; Pylkkänen, Liina

2012-02-01

The neural basis of syntax is a matter of substantial debate. In particular, the inferior frontal gyrus (IFG), or Broca's area, has been prominently linked to syntactic processing, but the anterior temporal lobe has been reported to be activated instead of IFG when manipulating the presence of syntactic structure. These findings are difficult to reconcile because they rely on different laboratory tasks which tap into distinct computations, and may only indirectly relate to natural sentence processing. Here we assessed neural correlates of syntactic structure building in natural language comprehension, free from artificial task demands. Subjects passively listened to Alice in Wonderland during functional magnetic resonance imaging and we correlated brain activity with a word-by-word measure of the amount syntactic structure analyzed. Syntactic structure building correlated with activity in the left anterior temporal lobe, but there was no evidence for a correlation between syntactic structure building and activity in inferior frontal areas. Our results suggest that the anterior temporal lobe computes syntactic structure under natural conditions. Copyright © 2010 Elsevier Inc. All rights reserved.

Anterior cingulate cortex instigates adaptive switches in choice by integrating immediate and delayed components of value in ventromedial prefrontal cortex.

PubMed

Economides, Marcos; Guitart-Masip, Marc; Kurth-Nelson, Zeb; Dolan, Raymond J

2014-02-26

Actions can lead to an immediate reward or punishment and a complex set of delayed outcomes. Adaptive choice necessitates the brain track and integrate both of these potential consequences. Here, we designed a sequential task whereby the decision to exploit or forego an available offer was contingent on comparing immediate value and a state-dependent future cost of expending a limited resource. Crucially, the dynamics of the task demanded frequent switches in policy based on an online computation of changing delayed consequences. We found that human subjects choose on the basis of a near-optimal integration of immediate reward and delayed consequences, with the latter computed in a prefrontal network. Within this network, anterior cingulate cortex (ACC) was dynamically coupled to ventromedial prefrontal cortex (vmPFC) when adaptive switches in choice were required. Our results suggest a choice architecture whereby interactions between ACC and vmPFC underpin an integration of immediate and delayed components of value to support flexible policy switching that accommodates the potential delayed consequences of an action.

Sensitivity of the lane change test as a measure of in-vehicle system demand.

PubMed

Young, Kristie L; Lenné, Michael G; Williamson, Amy R

2011-05-01

The Lane Change Test (LCT) is one of the growing number of methods developed to quantify driving performance degradation brought about by the use of in-vehicle devices. Beyond its validity and reliability, for such a test to be of practical use, it must also be sensitive to the varied demands of individual tasks. The current study evaluated the ability of several recent LCT lateral control and event detection parameters to discriminate between visual-manual and cognitive surrogate In-Vehicle Information System tasks with different levels of demand. Twenty-seven participants (mean age 24.4 years) completed a PC version of the LCT while performing visual search and math problem solving tasks. A number of the lateral control metrics were found to be sensitive to task differences, but the event detection metrics were less able to discriminate between tasks. The mean deviation and lane excursion measures were able to distinguish between the visual and cognitive tasks, but were less sensitive to the different levels of task demand. The other LCT metrics examined were less sensitive to task differences. A major factor influencing the sensitivity of at least some of the LCT metrics could be the type of lane change instructions given to participants. The provision of clear and explicit lane change instructions and further refinement of its metrics will be essential for increasing the utility of the LCT as an evaluation tool. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Attentional demands and daily functioning among community-dwelling elders.

PubMed

Jansen, Debra A

2006-01-01

Everyday life is full of numerous demands for attention that can affect the ability to function. For elders, examples of these attentional demands include negotiating public transportation and driving, sensory losses, and physical discomforts and worries that make it harder to concentrate and complete tasks. The purpose of this study was to examine the relation between attentional demands and the ability to manage daily activities requiring concentration for 54 community-dwelling elders (34 women, 20 men). As theorized, attentional demands correlated (r = -.58) significantly with daily functioning: Elders with more attentional demands perceived themselves as having greater difficulty managing tasks requiring concentration. Attentional demands accounted for a significant proportion of variance in functioning (12%), even after partialling out the effects of depressive symptoms and health. Findings support the theorized relation between attentional demands and daily functioning, as well as nursing interventions aimed at decreasing attentional demands to promote effective functioning for elders.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffrey Wishart

This document reports the work performed under Task 1.2.1.1: 'The development of a charge protocol to take advantage of off- and on-peak demand economics at facilities'. The work involved in this task included understanding the experimental results of the other tasks of SOW-5799 in order to take advantage of the economics of electricity pricing differences between on- and off-peak hours and the demonstrated charging and facility energy demand profiles. To undertake this task and to demonstrate the feasibility of plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) bi-directional electricity exchange potential, BEA has subcontracted Electric Transportation Applications (now knownmore » as ECOtality North America and hereafter ECOtality NA) to use the data from the demand and energy study to focus on reducing the electrical power demand of the charging facility. The use of delayed charging as well as vehicle-to-grid (V2G) and vehicle-to-building (V2B) operations were to be considered.« less

Does the walking task matter? Influence of different walking conditions on dual-task performances in young and older persons.

PubMed

Beurskens, Rainer; Bock, Otmar

2013-12-01

Previous literature suggests that age-related deficits of dual-task walking are particularly pronounced with second tasks that require continuous visual processing. Here we evaluate whether the difficulty of the walking task matters as well. To this end, participants were asked to walk along a straight pathway of 20m length in four different walking conditions: (a) wide path and preferred pace; (b) narrow path and preferred pace, (c) wide path and fast pace, (d) obstacled wide path and preferred pace. Each condition was performed concurrently with a task requiring visual processing or fine motor control, and all tasks were also performed alone which allowed us to calculate the dual-task costs (DTC). Results showed that the age-related increase of DTC is substantially larger with the visually demanding than with the motor-demanding task, more so when walking on a narrow or obstacled path. We attribute these observations to the fact that visual scanning of the environment becomes more crucial when walking in difficult terrains: the higher visual demand of those conditions accentuates the age-related deficits in coordinating them with a visual non-walking task. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

User-centric incentive design for participatory mobile phone sensing

NASA Astrophysics Data System (ADS)

Gao, Wei; Lu, Haoyang

2014-05-01

Mobile phone sensing is a critical underpinning of pervasive mobile computing, and is one of the key factors for improving people's quality of life in modern society via collective utilization of the on-board sensing capabilities of people's smartphones. The increasing demands for sensing services and ambient awareness in mobile environments highlight the necessity of active participation of individual mobile users in sensing tasks. User incentives for such participation have been continuously offered from an application-centric perspective, i.e., as payments from the sensing server, to compensate users' sensing costs. These payments, however, are manipulated to maximize the benefits of the sensing server, ignoring the runtime flexibility and benefits of participating users. This paper presents a novel framework of user-centric incentive design, and develops a universal sensing platform which translates heterogenous sensing tasks to a generic sensing plan specifying the task-independent requirements of sensing performance. We use this sensing plan as input to reduce three categories of sensing costs, which together cover the possible sources hindering users' participation in sensing.

The combined fatigue effects of sequential exposure to seated whole body vibration and physical, mental, or concurrent work demands

PubMed Central

Lang, Angelica E.; Stobart, Jamie; Kociolek, Aaron M.; Milosavljevic, Stephan; Trask, Catherine

2017-01-01

Many occupations in agriculture, construction, transportation, and forestry are non-routine, involving non-cyclical tasks, both discretionary and non-discretionary work breaks, and a mix of work activities. Workers in these industries are exposed to seated whole body vibration (WBV) and tasks consisting of physical, mental, or a combination of demands. Risk assessment tools for non-routinized jobs have emerged but there remains a need to understand the combined effects of different work demands to improve risk assessment methods and ultimately inform ergonomists and workers on optimum work arrangement and scheduling strategies. The objective of this study was to investigate fatigue-related human responses of WBV sequentially combined with physical, mental, or concurrent physical and mental demands. Sixteen healthy participants performed four conditions on four separate days: (1) physically demanding work, (2) mentally demanding work, (3) concurrent work, and (4) control quiet sitting. For each condition, participants performed two 15-minute bouts of the experimental task, separated by 30-minutes of simulated WBV based on realistic all-terrain vehicle (ATV) riding data. A test battery of fatigue measures consisting of biomechanical, physiological, cognitive, and sensorimotor measurements were collected at four interval periods: pre-session, after the first bout of the experimental task and before WBV, after WBV and before the second bout of the experimental task, and post-session. Nine measures demonstrated statistically significant time effects during the control condition; 11, 7, and 12 measures were significant in the physical, mental, and concurrent conditions, respectively. Overall, the effects of seated WBV in combination with different tasks are not additive but possibly synergistic or antagonistic. There appears to be a beneficial effect of seated ATV operation as a means of increasing task variation; but since excessive WBV may independently pose a health risk in the longer-term, these beneficial results may not be sensible as a long-term solution. PMID:29236752

The combined fatigue effects of sequential exposure to seated whole body vibration and physical, mental, or concurrent work demands.

PubMed

Yung, Marcus; Lang, Angelica E; Stobart, Jamie; Kociolek, Aaron M; Milosavljevic, Stephan; Trask, Catherine

2017-01-01

Many occupations in agriculture, construction, transportation, and forestry are non-routine, involving non-cyclical tasks, both discretionary and non-discretionary work breaks, and a mix of work activities. Workers in these industries are exposed to seated whole body vibration (WBV) and tasks consisting of physical, mental, or a combination of demands. Risk assessment tools for non-routinized jobs have emerged but there remains a need to understand the combined effects of different work demands to improve risk assessment methods and ultimately inform ergonomists and workers on optimum work arrangement and scheduling strategies. The objective of this study was to investigate fatigue-related human responses of WBV sequentially combined with physical, mental, or concurrent physical and mental demands. Sixteen healthy participants performed four conditions on four separate days: (1) physically demanding work, (2) mentally demanding work, (3) concurrent work, and (4) control quiet sitting. For each condition, participants performed two 15-minute bouts of the experimental task, separated by 30-minutes of simulated WBV based on realistic all-terrain vehicle (ATV) riding data. A test battery of fatigue measures consisting of biomechanical, physiological, cognitive, and sensorimotor measurements were collected at four interval periods: pre-session, after the first bout of the experimental task and before WBV, after WBV and before the second bout of the experimental task, and post-session. Nine measures demonstrated statistically significant time effects during the control condition; 11, 7, and 12 measures were significant in the physical, mental, and concurrent conditions, respectively. Overall, the effects of seated WBV in combination with different tasks are not additive but possibly synergistic or antagonistic. There appears to be a beneficial effect of seated ATV operation as a means of increasing task variation; but since excessive WBV may independently pose a health risk in the longer-term, these beneficial results may not be sensible as a long-term solution.

The effects of concurrent cognitive load on phonological processing in adults who stutter.

PubMed

Jones, Robin M; Fox, Robert A; Jacewicz, Ewa

2012-12-01

To determine whether phonological processing in adults who stutter (AWS) is disrupted by increased amounts of cognitive load in a concurrent attention-demanding task. Nine AWS and 9 adults who do not stutter (AWNS) participated. Using a dual-task paradigm, the authors presented word pairs for rhyme judgments and, concurrently, letter strings for memory recall. The rhyme judgment task manipulated rhyming type (rhyming/nonrhyming) and orthographic representation (similar/dissimilar). The memory recall task varied stimulus complexity (no letters, 3 letters, 5 letters). Rhyme judgment accuracy and reaction time (RT) were used to assess phonological processing, and letter recall accuracy was used to measure memory recall. For rhyme judgments, AWS were as accurate as AWNS, and the increase in the cognitive load did not affect rhyme judgment accuracy of either group. Significant group differences were found in RTs (delays by AWS were 241 ms greater). RTs of AWS were also slower in the most demanding rhyme condition and varied with the complexity of the memory task. Accuracy of letter recall of AWS was comparatively worse in the most demanding 5-letter condition. Phonological and cognitive processing of AWS is more vulnerable to disruptions caused by increased amounts of cognitive load in concurrent attention-demanding tasks.

Task preparation processes related to reward prediction precede those related to task-difficulty expectation

PubMed Central

Schevernels, Hanne; Krebs, Ruth M.; Santens, Patrick; Woldorff, Marty G.; Boehler, C. Nico

2013-01-01

Recently, attempts have been made to disentangle the neural underpinnings of preparatory processes related to reward and attention. Functional magnetic resonance imaging (fMRI) research showed that neural activity related to the anticipation of reward and to attentional demands invokes neural activity patterns featuring large-scale overlap, along with some differences and interactions. Due to the limited temporal resolution of fMRI, however, the temporal dynamics of these processes remain unclear. Here, we report an event-related potentials (ERP) study in which cued attentional demands and reward prospect were combined in a factorial design. Results showed that reward prediction dominated early cue processing, as well as the early and later parts of the contingent negative variation (CNV) slow-wave ERP component that has been associated with task-preparation processes. Moreover these reward-related electrophysiological effects correlated across participants with response-time speeding on reward-prospect trials. In contrast, cued attentional demands affected only the later part of the CNV, with the highest amplitudes following cues predicting high-difficulty potential-reward targets, thus suggesting maximal task preparation when the task requires it and entails reward prospect. Consequently, we suggest that task-preparation processes triggered by reward can arise earlier, and potentially more directly, than strategic top-down aspects of preparation based on attentional demands. PMID:24064071

Oxygen Level and LFP in Task-Positive and Task-Negative Areas: Bridging BOLD fMRI and Electrophysiology

PubMed Central

Bentley, William J.; Li, Jingfeng M.; Snyder, Abraham Z.; Raichle, Marcus E.; Snyder, Lawrence H.

2016-01-01

The human default mode network (DMN) shows decreased blood oxygen level dependent (BOLD) signals in response to a wide range of attention-demanding tasks. Our understanding of the specifics regarding the neural activity underlying these “task-negative” BOLD responses remains incomplete. We paired oxygen polarography, an electrode-based oxygen measurement technique, with standard electrophysiological recording to assess the relationship of oxygen and neural activity in task-negative posterior cingulate cortex (PCC), a hub of the DMN, and visually responsive task-positive area V3 in the awake macaque. In response to engaging visual stimulation, oxygen, LFP power, and multi-unit activity in PCC showed transient activation followed by sustained suppression. In V3, oxygen, LFP power, and multi-unit activity showed an initial phasic response to the stimulus followed by sustained activation. Oxygen responses were correlated with LFP power in both areas, although the apparent hemodynamic coupling between oxygen level and electrophysiology differed across areas. Our results suggest that oxygen responses reflect changes in LFP power and multi-unit activity and that either the coupling of neural activity to blood flow and metabolism differs between PCC and V3 or computing a linear transformation from a single LFP band to oxygen level does not capture the true physiological process. PMID:25385710

Distributed task coding throughout the multiple demand network of the human frontal-insular cortex.

PubMed

Stiers, Peter; Mennes, Maarten; Sunaert, Stefan

2010-08-01

The large variety of tasks that humans can perform is governed by a small number of key frontal-insular regions that are commonly active during task performance. Little is known about how this network distinguishes different tasks. We report on fMRI data in twelve participants while they performed four cognitive tasks. Of 20 commonly active frontal-insular regions in each hemisphere, five showed a BOLD response increase with increased task demands, regardless of the task. Although active in all tasks, each task invoked a unique response pattern across the voxels in each area that proved reliable in split-half multi-voxel correlation analysis. Consequently, voxels differed in their preference for one or more of the tasks. Voxel-based functional connectivity analyses revealed that same preference voxels distributed across all areas of the network constituted functional sub-networks that characterized the task being executed. Copyright 2010 Elsevier Inc. All rights reserved.

Brain noise is task dependent and region specific.

PubMed

Misić, Bratislav; Mills, Travis; Taylor, Margot J; McIntosh, Anthony R

2010-11-01

The emerging organization of anatomical and functional connections during human brain development is thought to facilitate global integration of information. Recent empirical and computational studies have shown that this enhanced capacity for information processing enables a diversified dynamic repertoire that manifests in neural activity as irregularity and noise. However, transient functional networks unfold over multiple time, scales and the embedding of a particular region depends not only on development, but also on the manner in which sensory and cognitive systems are engaged. Here we show that noise is a facet of neural activity that is also sensitive to the task context and is highly region specific. Children (6-16 yr) and adults (20-41 yr) performed a one-back face recognition task with inverted and upright faces. Neuromagnetic activity was estimated at several hundred sources in the brain by applying a beamforming technique to the magnetoencephalogram (MEG). During development, neural activity became more variable across the whole brain, with most robust increases in medial parietal regions, such as the precuneus and posterior cingulate cortex. For young children and adults, activity evoked by upright faces was more variable and noisy compared with inverted faces, and this effect was reliable only in the right fusiform gyrus. These results are consistent with the notion that upright faces engender a variety of integrative neural computations, such as the relations among facial features and their holistic constitution. This study shows that transient changes in functional integration modulated by task demand are evident in the variability of regional neural activity.

Optimizing Resource Utilization in Grid Batch Systems

NASA Astrophysics Data System (ADS)

Gellrich, Andreas

2012-12-01

On Grid sites, the requirements of the computing tasks (jobs) to computing, storage, and network resources differ widely. For instance Monte Carlo production jobs are almost purely CPU-bound, whereas physics analysis jobs demand high data rates. In order to optimize the utilization of the compute node resources, jobs must be distributed intelligently over the nodes. Although the job resource requirements cannot be deduced directly, jobs are mapped to POSIX UID/GID according to the VO, VOMS group and role information contained in the VOMS proxy. The UID/GID then allows to distinguish jobs, if users are using VOMS proxies as planned by the VO management, e.g. ‘role=production’ for Monte Carlo jobs. It is possible to setup and configure batch systems (queuing system and scheduler) at Grid sites based on these considerations although scaling limits were observed with the scheduler MAUI. In tests these limitations could be overcome with a home-made scheduler.

Reducing software mass through behavior control. [of planetary roving robots

NASA Technical Reports Server (NTRS)

Miller, David P.

1992-01-01

Attention is given to the tradeoff between communication and computation as regards a planetary rover (both these subsystems are very power-intensive, and both can be the major driver of the rover's power subsystem, and therefore the minimum mass and size of the rover). Software techniques that can be used to reduce the requirements on both communciation and computation, allowing the overall robot mass to be greatly reduced, are discussed. Novel approaches to autonomous control, called behavior control, employ an entirely different approach, and for many tasks will yield a similar or superior level of autonomy to traditional control techniques, while greatly reducing the computational demand. Traditional systems have several expensive processes that operate serially, while behavior techniques employ robot capabilities that run in parallel. Traditional systems make extensive world models, while behavior control systems use minimal world models or none at all.

Towards agile large-scale predictive modelling in drug discovery with flow-based programming design principles.

PubMed

Lampa, Samuel; Alvarsson, Jonathan; Spjuth, Ola

2016-01-01

Predictive modelling in drug discovery is challenging to automate as it often contains multiple analysis steps and might involve cross-validation and parameter tuning that create complex dependencies between tasks. With large-scale data or when using computationally demanding modelling methods, e-infrastructures such as high-performance or cloud computing are required, adding to the existing challenges of fault-tolerant automation. Workflow management systems can aid in many of these challenges, but the currently available systems are lacking in the functionality needed to enable agile and flexible predictive modelling. We here present an approach inspired by elements of the flow-based programming paradigm, implemented as an extension of the Luigi system which we name SciLuigi. We also discuss the experiences from using the approach when modelling a large set of biochemical interactions using a shared computer cluster.Graphical abstract.

Applied cognitive task analysis (ACTA): a practitioner's toolkit for understanding cognitive task demands.

PubMed

Militello, L G; Hutton, R J

1998-11-01

Cognitive task analysis (CTA) is a set of methods for identifying cognitive skills, or mental demands, needed to perform a task proficiently. The product of the task analysis can be used to inform the design of interfaces and training systems. However, CTA is resource intensive and has previously been of limited use to design practitioners. A streamlined method of CTA, Applied Cognitive Task Analysis (ACTA), is presented in this paper. ACTA consists of three interview methods that help the practitioner to extract information about the cognitive demands and skills required for a task. ACTA also allows the practitioner to represent this information in a format that will translate more directly into applied products, such as improved training scenarios or interface recommendations. This paper will describe the three methods, an evaluation study conducted to assess the usability and usefulness of the methods, and some directions for future research for making cognitive task analysis accessible to practitioners. ACTA techniques were found to be easy to use, flexible, and to provide clear output. The information and training materials developed based on ACTA interviews were found to be accurate and important for training purposes.

Age differences in high frequency phasic heart rate variability and performance response to increased executive function load in three executive function tasks

PubMed Central

Byrd, Dana L.; Reuther, Erin T.; McNamara, Joseph P. H.; DeLucca, Teri L.; Berg, William K.

2015-01-01

The current study examines similarity or disparity of a frontally mediated physiological response of mental effort among multiple executive functioning tasks between children and adults. Task performance and phasic heart rate variability (HRV) were recorded in children (6 to 10 years old) and adults in an examination of age differences in executive functioning skills during periods of increased demand. Executive load levels were varied by increasing the difficulty levels of three executive functioning tasks: inhibition (IN), working memory (WM), and planning/problem solving (PL). Behavioral performance decreased in all tasks with increased executive demand in both children and adults. Adults’ phasic high frequency HRV was suppressed during the management of increased IN and WM load. Children’s phasic HRV was suppressed during the management of moderate WM load. HRV was not suppressed during either children’s or adults’ increasing load during the PL task. High frequency phasic HRV may be most sensitive to executive function tasks that have a time-response pressure, and simply requiring performance on a self-paced task requiring frontal lobe activation may not be enough to generate HRV responsitivity to increasing demand. PMID:25798113

Cognitive and Collaborative Demands of Freight Conductor Activities: Results and Implications of a Cognitive Task Analysis.

DOT National Transportation Integrated Search

2011-09-19

This paper reports the results of a cognitive task analysis (CTA) that examined the cognitive and collaborative demands placed on conductors and the knowledge and skills that experienced conductors have developed that enable them to operate safely an...

Cognitive and collaborative demands of freight conductor activities: results and implications of a cognitive task analysis

DOT National Transportation Integrated Search

2012-07-31

This report presents the results of a cognitive task analysis (CTA) that examined the cognitive and collaborative demands placed on conductors, as well as the knowledge and skills that experienced conductors have developed that enable them to operate...

Estimating Demand for Alternatives to Cigarettes With Online Purchase Tasks

PubMed Central

O’Connor, Richard J.; June, Kristie M.; Bansal-Travers, Maansi; Rousu, Matthew C.; Thrasher, James F.; Hyland, Andrew; Cummings, K. Michael

2013-01-01

Objectives This study explored how advertising affects demand for cigarettes and potential substitutes, including snus, dissolvable tobacco, and medicinal nicotine. Methods A web-based experiment randomized 1062 smokers to see advertisements for alternative nicotine products or soft drinks, then complete a series of purchase tasks, which were used to estimate demand elasticity, peak consumption, and cross-price elasticity (CPE) for tobacco products. Results Lower demand elasticity and greater peak consumption were seen for cigarettes compared to all alternative products (p < .05). CPE did not differ across the alternative products (p ≤ .03). Seeing relevant advertisements was not significantly related to demand. Conclusions These findings suggest significantly lower demand for alternative nicotine sources among smokers than previously revealed. PMID:24034685

Differential impact of continuous theta-burst stimulation over left and right DLPFC on planning.

PubMed

Kaller, Christoph P; Heinze, Katharina; Frenkel, Annekathrein; Läppchen, Claus H; Unterrainer, Josef M; Weiller, Cornelius; Lange, Rüdiger; Rahm, Benjamin

2013-01-01

Most neuroimaging studies on planning report bilateral activations of the dorsolateral prefrontal cortex (dlPFC). Recently, these concurrent activations of left and right dlPFC have been shown to double dissociate with different cognitive demands imposed by the planning task: Higher demands on the extraction of task-relevant information led to stronger activation in left dlPFC, whereas higher demands on the integration of interdependent information into a coherent action sequence entailed stronger activation of right dlPFC. Here, we used continuous theta-burst stimulation (cTBS) to investigate the supposed causal structure-function mapping underlying this double dissociation. Two groups of healthy subjects (left-lateralized stimulation, n = 26; right-lateralized stimulation, n = 26) were tested within-subject on a variant of the Tower of London task following either real cTBS over dlPFC or sham stimulation over posterior parietal cortex. Results revealed that, irrespective of specific task demands, cTBS over left and right dlPFC was associated with a global decrease and increase, respectively, in initial planning times compared to sham stimulation. Moreover, no interaction between task demands and stimulation type (real vs. sham) and/or stimulation side (left vs. right hemisphere) were found. Together, against expectations from previous neuroimaging data, lateralized cTBS did not lead to planning-parameter specific changes in performance, but instead revealed a global asymmetric pattern of faster versus slower task processing after left versus right cTBS. This global asymmetry in the absence of any task-parameter specific impact of cTBS suggests that different levels of information processing may span colocalized, but independent axes of functional lateralization in the dlPFC. Copyright © 2011 Wiley Periodicals, Inc.

Insula Demonstrates a Non-Linear Response to Varying Demand for Cognitive Control and Weaker Resting Connectivity With the Executive Control Network in Smokers.

PubMed

Fedota, John R; Matous, Allison L; Salmeron, Betty Jo; Gu, Hong; Ross, Thomas J; Stein, Elliot A

2016-09-01

Deficits in cognitive control processes are a primary characteristic of nicotine addiction. However, while network-based connectivity measures of dysfunction have frequently been observed, empirical evidence of task-based dysfunction in these processes has been inconsistent. Here, in a sample of smokers (n=35) and non-smokers (n=21), a previously validated parametric flanker task is employed to characterize addiction-related alterations in responses to varying (ie, high, intermediate, and low) demands for cognitive control. This approach yields a demand-response curve that aims to characterize potential non-linear responses to increased demand for control, including insensitivities or lags in fully activating the cognitive control network. We further used task-based differences in activation between groups as seeds for resting-state analysis of network dysfunction in an effort to more closely link prior inconsistencies in task-related activation with evidence of impaired network connectivity in smokers. For both smokers and non-smokers, neuroimaging results showed similar increases in activation in brain areas associated with cognitive control. However, reduced activation in right insula was seen only in smokers and only when processing intermediate demand for cognitive control. Further, in smokers, this task-modulated right insula showed weaker functional connectivity with the superior frontal gyrus, a component of the task-positive executive control network. These results demonstrate that the neural instantiation of salience attribution in smokers is both more effortful to fully activate and has more difficulty communicating with the exogenous, task-positive, executive control network. Together, these findings further articulate the cognitive control dysfunction associated with smoking and illustrate a specific brain circuit potentially responsible.

SPIKY: a graphical user interface for monitoring spike train synchrony

PubMed Central

Mulansky, Mario; Bozanic, Nebojsa

2015-01-01

Techniques for recording large-scale neuronal spiking activity are developing very fast. This leads to an increasing demand for algorithms capable of analyzing large amounts of experimental spike train data. One of the most crucial and demanding tasks is the identification of similarity patterns with a very high temporal resolution and across different spatial scales. To address this task, in recent years three time-resolved measures of spike train synchrony have been proposed, the ISI-distance, the SPIKE-distance, and event synchronization. The Matlab source codes for calculating and visualizing these measures have been made publicly available. However, due to the many different possible representations of the results the use of these codes is rather complicated and their application requires some basic knowledge of Matlab. Thus it became desirable to provide a more user-friendly and interactive interface. Here we address this need and present SPIKY, a graphical user interface that facilitates the application of time-resolved measures of spike train synchrony to both simulated and real data. SPIKY includes implementations of the ISI-distance, the SPIKE-distance, and the SPIKE-synchronization (an improved and simplified extension of event synchronization) that have been optimized with respect to computation speed and memory demand. It also comprises a spike train generator and an event detector that makes it capable of analyzing continuous data. Finally, the SPIKY package includes additional complementary programs aimed at the analysis of large numbers of datasets and the estimation of significance levels. PMID:25744888

SPIKY: a graphical user interface for monitoring spike train synchrony.

PubMed

Kreuz, Thomas; Mulansky, Mario; Bozanic, Nebojsa

2015-05-01

Techniques for recording large-scale neuronal spiking activity are developing very fast. This leads to an increasing demand for algorithms capable of analyzing large amounts of experimental spike train data. One of the most crucial and demanding tasks is the identification of similarity patterns with a very high temporal resolution and across different spatial scales. To address this task, in recent years three time-resolved measures of spike train synchrony have been proposed, the ISI-distance, the SPIKE-distance, and event synchronization. The Matlab source codes for calculating and visualizing these measures have been made publicly available. However, due to the many different possible representations of the results the use of these codes is rather complicated and their application requires some basic knowledge of Matlab. Thus it became desirable to provide a more user-friendly and interactive interface. Here we address this need and present SPIKY, a graphical user interface that facilitates the application of time-resolved measures of spike train synchrony to both simulated and real data. SPIKY includes implementations of the ISI-distance, the SPIKE-distance, and the SPIKE-synchronization (an improved and simplified extension of event synchronization) that have been optimized with respect to computation speed and memory demand. It also comprises a spike train generator and an event detector that makes it capable of analyzing continuous data. Finally, the SPIKY package includes additional complementary programs aimed at the analysis of large numbers of datasets and the estimation of significance levels. Copyright © 2015 the American Physiological Society.

Computational wear assessment of hard on hard hip implants subject to physically demanding tasks.

PubMed

Nithyaprakash, R; Shankar, S; Uddin, M S

2018-05-01

Hip implants subject to gait loading due to occupational activities are potentially prone to failures such as osteolysis and aseptic loosening, causing painful revision surgeries. Highly risky gait activities such as carrying a load, stairs up or down and ladder up or down may cause excessive loading at the hip joint, resulting in generation of wear and related debris. Estimation of wear under the above gait activities is thus crucial to design and develop a new and improved implant component. With this motivation, this paper presents an assessment of wear generation of PCD-on-PCD (poly crystalline diamond) hip implants using finite element (FE) analysis. Three-dimensional (3D) FE model of hip implant along with peak gait and peak flexion angle for each activity was used to estimate wear of PCD for 10 million cycles. The maximum and minimum initial contact pressures of 206.19 MPa and 151.89 MPa were obtained for carrying load of 40 kg and sitting down or getting up activity. The simulation results obtained from finite element model also revealed that the maximum linear wear of 0.585 μm occurred for the patients frequently involved in sitting down or getting up gait activity and maximum volumetric wear of 0.025 mm 3 for ladder up gait activity. The stair down activity showed the least linear and volumetric wear of 0.158 μm and 0.008 mm 3 , respectively, at the end of 10 million cycles. Graphical abstract Computational wear assessment of hip implants subjected to physically demanding tasks.

Blinking supervision in a working environment

NASA Astrophysics Data System (ADS)

Morcego, Bernardo; Argilés, Marc; Cabrerizo, Marc; Cardona, Genís; Pérez, Ramon; Pérez-Cabré, Elisabet; Gispets, Joan

2016-02-01

The health of the ocular surface requires blinks of the eye to be frequent in order to provide moisture and to renew the tear film. However, blinking frequency has been shown to decrease in certain conditions such as when subjects are conducting tasks with high cognitive and visual demands. These conditions are becoming more common as people work or spend their leisure time in front of video display terminals. Supervision of blinking frequency in such environments is possible, thanks to the availability of computer-integrated cameras. Therefore, the aim of the present study is to develop an algorithm for the detection of eye blinks and to test it, in a number of videos captured, while subjects are conducting a variety of tasks in front of the computer. The sensitivity of the algorithm for blink detection was found to be of 87.54% (range 30% to 100%), with a mean false-positive rate of 0.19% (range 0% to 1.7%), depending on the illumination conditions during which the image was captured and other computer-user spatial configurations. The current automatic process is based on a partly modified pre-existing eye detection and image processing algorithms and consists of four stages that are aimed at eye detection, eye tracking, iris detection and segmentation, and iris height/width ratio assessment.

A framework for characterizing eHealth literacy demands and barriers.

PubMed

Chan, Connie V; Kaufman, David R

2011-11-17

Consumer eHealth interventions are of a growing importance in the individual management of health and health behaviors. However, a range of access, resources, and skills barriers prevent health care consumers from fully engaging in and benefiting from the spectrum of eHealth interventions. Consumers may engage in a range of eHealth tasks, such as participating in health discussion forums and entering information into a personal health record. eHealth literacy names a set of skills and knowledge that are essential for productive interactions with technology-based health tools, such as proficiency in information retrieval strategies, and communicating health concepts effectively. We propose a theoretical and methodological framework for characterizing complexity of eHealth tasks, which can be used to diagnose and describe literacy barriers and inform the development of solution strategies. We adapted and integrated two existing theoretical models relevant to the analysis of eHealth literacy into a single framework to systematically categorize and describe task demands and user performance on tasks needed by health care consumers in the information age. The method derived from the framework is applied to (1) code task demands using a cognitive task analysis, and (2) code user performance on tasks. The framework and method are applied to the analysis of a Web-based consumer eHealth task with information-seeking and decision-making demands. We present the results from the in-depth analysis of the task performance of a single user as well as of 20 users on the same task to illustrate both the detailed analysis and the aggregate measures obtained and potential analyses that can be performed using this method. The analysis shows that the framework can be used to classify task demands as well as the barriers encountered in user performance of the tasks. Our approach can be used to (1) characterize the challenges confronted by participants in performing the tasks, (2) determine the extent to which application of the framework to the cognitive task analysis can predict and explain the problems encountered by participants, and (3) inform revisions to the framework to increase accuracy of predictions. The results of this illustrative application suggest that the framework is useful for characterizing task complexity and for diagnosing and explaining barriers encountered in task completion. The framework and analytic approach can be a potentially powerful generative research platform to inform development of rigorous eHealth examination and design instruments, such as to assess eHealth competence, to design and evaluate consumer eHealth tools, and to develop an eHealth curriculum.

A Framework for Characterizing eHealth Literacy Demands and Barriers

PubMed Central

Chan, Connie V

2011-01-01

Background Consumer eHealth interventions are of a growing importance in the individual management of health and health behaviors. However, a range of access, resources, and skills barriers prevent health care consumers from fully engaging in and benefiting from the spectrum of eHealth interventions. Consumers may engage in a range of eHealth tasks, such as participating in health discussion forums and entering information into a personal health record. eHealth literacy names a set of skills and knowledge that are essential for productive interactions with technology-based health tools, such as proficiency in information retrieval strategies, and communicating health concepts effectively. Objective We propose a theoretical and methodological framework for characterizing complexity of eHealth tasks, which can be used to diagnose and describe literacy barriers and inform the development of solution strategies. Methods We adapted and integrated two existing theoretical models relevant to the analysis of eHealth literacy into a single framework to systematically categorize and describe task demands and user performance on tasks needed by health care consumers in the information age. The method derived from the framework is applied to (1) code task demands using a cognitive task analysis, and (2) code user performance on tasks. The framework and method are applied to the analysis of a Web-based consumer eHealth task with information-seeking and decision-making demands. We present the results from the in-depth analysis of the task performance of a single user as well as of 20 users on the same task to illustrate both the detailed analysis and the aggregate measures obtained and potential analyses that can be performed using this method. Results The analysis shows that the framework can be used to classify task demands as well as the barriers encountered in user performance of the tasks. Our approach can be used to (1) characterize the challenges confronted by participants in performing the tasks, (2) determine the extent to which application of the framework to the cognitive task analysis can predict and explain the problems encountered by participants, and (3) inform revisions to the framework to increase accuracy of predictions. Conclusions The results of this illustrative application suggest that the framework is useful for characterizing task complexity and for diagnosing and explaining barriers encountered in task completion. The framework and analytic approach can be a potentially powerful generative research platform to inform development of rigorous eHealth examination and design instruments, such as to assess eHealth competence, to design and evaluate consumer eHealth tools, and to develop an eHealth curriculum. PMID:22094891

Effects of dynamic-demand-control appliances on the power grid frequency.

PubMed

Tchuisseu, E B Tchawou; Gomila, D; Brunner, D; Colet, P

2017-08-01

Power grid frequency control is a demanding task requiring expensive idle power plants to adapt the supply to the fluctuating demand. An alternative approach is controlling the demand side in such a way that certain appliances modify their operation to adapt to the power availability. This is especially important to achieve a high penetration of renewable energy sources. A number of methods to manage the demand side have been proposed. In this work we focus on dynamic demand control (DDC), where smart appliances can delay their switchings depending on the frequency of the system. We introduce a simple model to study the effects of DDC on the frequency of the power grid. The model includes the power plant equations, a stochastic model for the demand that reproduces, adjusting a single parameter, the statistical properties of frequency fluctuations measured experimentally, and a generic DDC protocol. We find that DDC can reduce small and medium-size fluctuations but it can also increase the probability of observing large frequency peaks due to the necessity of recovering pending task. We also conclude that a deployment of DDC around 30-40% already allows a significant reduction of the fluctuations while keeping the number of pending tasks low.

Effects of dynamic-demand-control appliances on the power grid frequency

NASA Astrophysics Data System (ADS)

Tchuisseu, E. B. Tchawou; Gomila, D.; Brunner, D.; Colet, P.

2017-08-01

Power grid frequency control is a demanding task requiring expensive idle power plants to adapt the supply to the fluctuating demand. An alternative approach is controlling the demand side in such a way that certain appliances modify their operation to adapt to the power availability. This is especially important to achieve a high penetration of renewable energy sources. A number of methods to manage the demand side have been proposed. In this work we focus on dynamic demand control (DDC), where smart appliances can delay their switchings depending on the frequency of the system. We introduce a simple model to study the effects of DDC on the frequency of the power grid. The model includes the power plant equations, a stochastic model for the demand that reproduces, adjusting a single parameter, the statistical properties of frequency fluctuations measured experimentally, and a generic DDC protocol. We find that DDC can reduce small and medium-size fluctuations but it can also increase the probability of observing large frequency peaks due to the necessity of recovering pending task. We also conclude that a deployment of DDC around 30-40% already allows a significant reduction of the fluctuations while keeping the number of pending tasks low.

Isolating behavioural economic indices of demand in relation to nicotine dependence.

PubMed

Chase, Henry W; Mackillop, James; Hogarth, Lee

2013-03-01

Characterisation of drug dependence using principles from behavioural economics has provided a more detailed understanding of the disorder. Although questionnaires assessing economic demand for cigarettes have extended these principles to nicotine addiction, aspects of the reliability and selectivity of these questionnaires remain uncertain. Across two experiments, we attempted to reproduce significant associations of the cigarette purchase task with nicotine dependence in a young adult population of smokers and contrasted this measure with a novel chocolate purchase task. We also examined the association between these measures and performance on a preference task, measuring preference for cigarettes and chocolate. Questionnaire measures were used within a university setting. In experiment 1, we observed associations between nicotine dependence and measures of behavioural economic demand for cigarettes, particularly O (max). In experiment 2, we replicated these findings again and extended them to show that similar correlations between nicotine dependence and demand for chocolate were not observed. Moreover, the indices of demand and choices on a concurrent choice cigarette task were moderately associated with each other and independently associated with nicotine dependence. The two experiments clearly supported previous findings regarding the association between nicotine dependence and economic demand for cigarettes. We extend these observations by showing that the generalisation of economic demand across different commodities is relatively weak, but that generalisation across different procedures is strong. Our results therefore support behavioural economic models of nicotine addiction which emphasise a robust proximal role for the incentive value of cigarettes.

Streaming support for data intensive cloud-based sequence analysis.

PubMed

Issa, Shadi A; Kienzler, Romeo; El-Kalioby, Mohamed; Tonellato, Peter J; Wall, Dennis; Bruggmann, Rémy; Abouelhoda, Mohamed

2013-01-01

Cloud computing provides a promising solution to the genomics data deluge problem resulting from the advent of next-generation sequencing (NGS) technology. Based on the concepts of "resources-on-demand" and "pay-as-you-go", scientists with no or limited infrastructure can have access to scalable and cost-effective computational resources. However, the large size of NGS data causes a significant data transfer latency from the client's site to the cloud, which presents a bottleneck for using cloud computing services. In this paper, we provide a streaming-based scheme to overcome this problem, where the NGS data is processed while being transferred to the cloud. Our scheme targets the wide class of NGS data analysis tasks, where the NGS sequences can be processed independently from one another. We also provide the elastream package that supports the use of this scheme with individual analysis programs or with workflow systems. Experiments presented in this paper show that our solution mitigates the effect of data transfer latency and saves both time and cost of computation.

Estimating the executive demands of a one-back choice reaction time task by means of the selective interference paradigm.

PubMed

Szmalec, Arnaud; Vandierendonck, André

2007-08-01

The present study proposes a new executive task, the one-back choice reaction time (RT) task, and implements the selective interference paradigm to estimate the executive demands of the processing components involved in this task. Based on the similarities between a one-back choice RT task and the n-back updating task, it was hypothesized that one-back delaying of a choice reaction involves executive control. In three experiments, framed within Baddeley's (1986) working-memory model, a one-back choice RT task, a choice RT task, articulatory suppression, and matrix tapping were performed concurrently with primary tasks involving verbal, visuospatial, and executive processing. The results demonstrate that one-back delaying of a choice reaction interferes with tasks requiring executive control, while the potential interference at the level of the verbal or visuospatial working memory slave systems remains minimal.

Dynamical aspects of behavior generation under constraints

PubMed Central

Harter, Derek; Achunala, Srinivas

2007-01-01

Dynamic adaptation is a key feature of brains helping to maintain the quality of their performance in the face of increasingly difficult constraints. How to achieve high-quality performance under demanding real-time conditions is an important question in the study of cognitive behaviors. Animals and humans are embedded in and constrained by their environments. Our goal is to improve the understanding of the dynamics of the interacting brain–environment system by studying human behaviors when completing constrained tasks and by modeling the observed behavior. In this article we present results of experiments with humans performing tasks on the computer under variable time and resource constraints. We compare various models of behavior generation in order to describe the observed human performance. Finally we speculate on mechanisms how chaotic neurodynamics can contribute to the generation of flexible human behaviors under constraints. PMID:19003514

Assessing the interplay between the shoulders and low back during manual patient handling techniques in a nursing setting.

PubMed

Belbeck, Alicia; Cudlip, Alan C; Dickerson, Clark R

2014-01-01

The purpose of this research was to quantify shoulder demands during freestyle manual patient handling (MPH) tasks and determine whether approaches intended to prevent low back injury increased shoulder demands. Twenty females completed 5 MPH tasks found commonly in hospital settings before and after a training session using current workplace MPH guidelines. Most normalized muscle activity indices and ratings of perceived exertion decreased following training at both the low back and shoulders, but were more pronounced at the low back. There was little evidence to suggest that mechanical demands were transferred from the low back to the shoulders following the training session. The study generally supports continued use of the recommended MPH techniques, but indicates that several tasks generate high muscular demands and should be avoided if possible.

Demands on attention and the role of response priming in visual discrimination of feature conjunctions.

PubMed

Fournier, Lisa R; Herbert, Rhonda J; Farris, Carrie

2004-10-01

This study examined how response mapping of features within single- and multiple-feature targets affects decision-based processing and attentional capacity demands. Observers judged the presence or absence of 1 or 2 target features within an object either presented alone or with distractors. Judging the presence of 2 features relative to the less discriminable of these features alone was faster (conjunction benefits) when the task-relevant features differed in discriminability and were consistently mapped to responses. Conjunction benefits were attributed to asynchronous decision priming across attended, task-relevant dimensions. A failure to find conjunction benefits for disjunctive conjunctions was attributed to increased memory demands and variable feature-response mapping for 2- versus single-feature targets. Further, attentional demands were similar between single- and 2-feature targets when response mapping, memory demands, and discriminability of the task-relevant features were equated between targets. Implications of the findings for recent attention models are discussed. (c) 2004 APA, all rights reserved

The cooking task: making a meal of executive functions

PubMed Central

Doherty, T. A.; Barker, L. A.; Denniss, R.; Jalil, A.; Beer, M. D.

2015-01-01

Current standardized neuropsychological tests may fail to accurately capture real-world executive deficits. We developed a computer-based Cooking Task (CT) assessment of executive functions and trialed the measure with a normative group before use with a head-injured population. Forty-six participants completed the computerized CT and subtests from standardized neuropsychological tasks, including the Tower and Sorting Tests of executive function from the Delis-Kaplan Executive Function System (D-KEFS) and the Cambridge prospective memory test (CAMPROMPT), in order to examine whether standardized executive function tasks, predicted performance on measurement indices from the CT. Findings showed that verbal comprehension, rule detection and prospective memory contributed to measures of prospective planning accuracy and strategy implementation of the CT. Results also showed that functions necessary for cooking efficacy differ as an effect of task demands (difficulty levels). Performance on rule detection, strategy implementation and flexible thinking executive function measures contributed to accuracy on the CT. These findings raise questions about the functions captured by present standardized tasks particularly at varying levels of difficulty and during dual-task performance. Our preliminary findings also indicate that CT measures can effectively distinguish between executive function and Full Scale IQ abilities. Results of the present study indicate that the CT shows promise as an ecologically valid measure of executive function for future use with a head-injured population and indexes selective executive function’s captured by standardized tests. PMID:25717294

The cooking task: making a meal of executive functions.

PubMed

Doherty, T A; Barker, L A; Denniss, R; Jalil, A; Beer, M D

2015-01-01

Current standardized neuropsychological tests may fail to accurately capture real-world executive deficits. We developed a computer-based Cooking Task (CT) assessment of executive functions and trialed the measure with a normative group before use with a head-injured population. Forty-six participants completed the computerized CT and subtests from standardized neuropsychological tasks, including the Tower and Sorting Tests of executive function from the Delis-Kaplan Executive Function System (D-KEFS) and the Cambridge prospective memory test (CAMPROMPT), in order to examine whether standardized executive function tasks, predicted performance on measurement indices from the CT. Findings showed that verbal comprehension, rule detection and prospective memory contributed to measures of prospective planning accuracy and strategy implementation of the CT. Results also showed that functions necessary for cooking efficacy differ as an effect of task demands (difficulty levels). Performance on rule detection, strategy implementation and flexible thinking executive function measures contributed to accuracy on the CT. These findings raise questions about the functions captured by present standardized tasks particularly at varying levels of difficulty and during dual-task performance. Our preliminary findings also indicate that CT measures can effectively distinguish between executive function and Full Scale IQ abilities. Results of the present study indicate that the CT shows promise as an ecologically valid measure of executive function for future use with a head-injured population and indexes selective executive function's captured by standardized tests.

How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands

PubMed Central

Allon, Ayala S.; Balaban, Halely; Luria, Roy

2014-01-01

In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item’s resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms. PMID:24734026

The influences of obesity and age on functional performance during intermittent upper extremity tasks.

PubMed

Cavuoto, Lora A; Nussbaum, Maury A

2014-01-01

In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can modify job demands and affect worker capacity in terms of muscular and psychomotor function. However, there is a lack of empirical studies quantifying the work-relevant (or ergonomic) impacts related to task demands, capacities, and their potential imbalance. Eight obese and eight non-obese participants from each of two age groups (18-25 and 50-65 years) completed three endurance tasks involving fixed levels of task demands: hand grip, shoulder flexion, and a simulated assembly task using the upper extremity. Measures of functional performance including endurance, discomfort, motor control, and task performance were recorded for each of the task conditions. Endurance times were ∼60% longer for the non-obese group, and older participants had longer endurance times; however there was no evidence of interactive effects of obesity and age. Obesity also impaired functional performance, as indicated by higher rates of strength loss, increases in discomfort, and declines in task performance. These observed impairments may reflect underlying physiological differences among individuals who are obese, but that are independent of age. Obesity-related impairments may have implications for the design of work duration and demand level to prevent fatigue development for workers who are obese.

Behavioral Economics of Cigarette Purchase Tasks: Within-Subject Comparison of Real, Potentially Real, and Hypothetical Cigarettes

PubMed Central

Wilson, A. George; Franck, Christopher T.; Koffarnus, Mikhail N.

2016-01-01

Abstract Introduction: Hypothetical rewards are commonly used in studies of laboratory-based tobacco demand. However, behavioral economic demand procedures require confirmation that the behavior elicited from real and hypothetical reward types are equivalent, and that results attained from these procedures are comparable to other accepted tasks, such as the hypothetical purchase task. Methods: Nineteen smokers were asked to purchase 1 week’s worth of cigarettes that they would consume over the following week either at one price that incrementally increased across four weekly sessions (“real” sessions) or four prices in a single session (“potentially real” session), one of which was randomly chosen to be actualized. At each session, participants also completed a hypothetical cigarette purchase task. After each week, participants reported the number of cigarettes they actually smoked. Results: Demand was found to be equivalent under both the real and potentially real reward conditions but statistically different from the demand captured in the hypothetical purchase task. However, the amounts purchased at specific prices in the hypothetical purchase task were significantly correlated with the amount purchased at comparable prices in the other two tasks (except for the highest price examined in both tasks of $1.00 per cigarette). Number of cigarettes consumed that were obtained outside of the study was correlated with study cigarette price. Conclusions: Combined, these results suggest that purchasing behavior during potentially real sessions (1) was not functionally different from real sessions, (2) imposes fewer costs to the experimenter, and (3) has high levels of both internal and external validity. PMID:26187389

Infrastructure Systems for Advanced Computing in E-science applications

NASA Astrophysics Data System (ADS)

Terzo, Olivier

2013-04-01

In the e-science field are growing needs for having computing infrastructure more dynamic and customizable with a model of use "on demand" that follow the exact request in term of resources and storage capacities. The integration of grid and cloud infrastructure solutions allows us to offer services that can adapt the availability in terms of up scaling and downscaling resources. The main challenges for e-sciences domains will on implement infrastructure solutions for scientific computing that allow to adapt dynamically the demands of computing resources with a strong emphasis on optimizing the use of computing resources for reducing costs of investments. Instrumentation, data volumes, algorithms, analysis contribute to increase the complexity for applications who require high processing power and storage for a limited time and often exceeds the computational resources that equip the majority of laboratories, research Unit in an organization. Very often it is necessary to adapt or even tweak rethink tools, algorithms, and consolidate existing applications through a phase of reverse engineering in order to adapt them to a deployment on Cloud infrastructure. For example, in areas such as rainfall monitoring, meteorological analysis, Hydrometeorology, Climatology Bioinformatics Next Generation Sequencing, Computational Electromagnetic, Radio occultation, the complexity of the analysis raises several issues such as the processing time, the scheduling of tasks of processing, storage of results, a multi users environment. For these reasons, it is necessary to rethink the writing model of E-Science applications in order to be already adapted to exploit the potentiality of cloud computing services through the uses of IaaS, PaaS and SaaS layer. An other important focus is on create/use hybrid infrastructure typically a federation between Private and public cloud, in fact in this way when all resources owned by the organization are all used it will be easy with a federate cloud infrastructure to add some additional resources form the Public cloud for following the needs in term of computational and storage resources and release them where process are finished. Following the hybrid model, the scheduling approach is important for managing both cloud models. Thanks to this model infrastructure every time resources are available for additional request in term of IT capacities that can used "on demand" for a limited time without having to proceed to purchase additional servers.

Shaped by our thoughts--a new task to assess spontaneous cognition and its associated neural correlates in the default network.

PubMed

O'Callaghan, Claire; Shine, James M; Lewis, Simon J G; Andrews-Hanna, Jessica R; Irish, Muireann

2015-02-01

Self-generated cognition, or mind wandering, refers to the quintessentially human tendency to withdraw from the immediate external environment and engage in internally driven mentation. This thought activity is suggested to be underpinned by a distributed set of regions in the brain, referred to as the default network. To date, experimental assessment of mind wandering has typically taken place during performance of a concurrent attention-demanding task. The attentional demands of concurrent tasks can influence the emergence of mind wandering, and their application to clinical disorders with reduced cognitive resources is limited. Furthermore, few paradigms have investigated the phenomenological content of mind wandering episodes. Here, we present data from a novel thought sampling task that measures both the frequency and qualitative content of mind wandering, in the absence of a concurrent task to reduce cognitive demand. The task was validated in a non-pathological cohort of 31 older controls and resting-state functional connectivity analyses in a subset of participants (n=18) was conducted to explore the neural bases of mind wandering. Overall, instances of mind wandering were found to occur in 37% of experimental trials. Resting state functional connectivity analyses confirmed that mind wandering frequency was associated with regional patterns of both increased and decreased default network connectivity, namely in the temporal lobe, posterior cingulate cortex and dorsal medial prefrontal cortex. Our findings demonstrate that the novel task provides a context of low cognitive demand, which is conducive to mind wandering. Furthermore, performance on the task is associated with specific patterns of functional connectivity in the default network. Together, this new paradigm offers an important avenue to investigate the frequency and content of mind wandering in the context of low cognitive demands, and has significant potential to be applied in clinical conditions with reduced cognitive resources. Copyright © 2014 Elsevier Inc. All rights reserved.

Specialization in the default mode: Task-induced brain deactivations dissociate between visual working memory and attention.

PubMed

Mayer, Jutta S; Roebroeck, Alard; Maurer, Konrad; Linden, David E J

2010-01-01

The idea of an organized mode of brain function that is present as default state and suspended during goal-directed behaviors has recently gained much interest in the study of human brain function. The default mode hypothesis is based on the repeated observation that certain brain areas show task-induced deactivations across a wide range of cognitive tasks. In this event-related functional resonance imaging study we tested the default mode hypothesis by comparing common and selective patterns of BOLD deactivation in response to the demands on visual attention and working memory (WM) that were independently modulated within one task. The results revealed task-induced deactivations within regions of the default mode network (DMN) with a segregation of areas that were additively deactivated by an increase in the demands on both attention and WM, and areas that were selectively deactivated by either high attentional demand or WM load. Attention-selective deactivations appeared in the left ventrolateral and medial prefrontal cortex and the left lateral temporal cortex. Conversely, WM-selective deactivations were found predominantly in the right hemisphere including the medial-parietal, the lateral temporo-parietal, and the medial prefrontal cortex. Moreover, during WM encoding deactivated regions showed task-specific functional connectivity. These findings demonstrate that task-induced deactivations within parts of the DMN depend on the specific characteristics of the attention and WM components of the task. The DMN can thus be subdivided into a set of brain regions that deactivate indiscriminately in response to cognitive demand ("the core DMN") and a part whose deactivation depends on the specific task. 2009 Wiley-Liss, Inc.

Alpha power increases in right parietal cortex reflects focused internal attention

PubMed Central

Benedek, Mathias; Schickel, Rainer J.; Jauk, Emanuel; Fink, Andreas; Neubauer, Aljoscha C.

2014-01-01

This study investigated the functional significance of EEG alpha power increases, a finding that is consistently observed in various memory tasks and specifically during divergent thinking. It was previously shown that alpha power is increased when tasks are performed in mind—e.g., when bottom-up processing is prevented. This study aimed to examine the effect of task-immanent differences in bottom-up processing demands by comparing two divergent thinking tasks, one intrinsically relying on bottom-up processing (sensory-intake task) and one that is not (sensory-independence task). In both tasks, stimuli were masked in half of the trials to establish conditions of higher and lower internal processing demands. In line with the hypotheses, internal processing affected performance and led to increases in alpha power only in the sensory-intake task, whereas the sensory-independence task showed high levels of task-related alpha power in both conditions. Interestingly, conditions involving focused internal attention showed a clear lateralization with higher alpha power in parietal regions of the right hemisphere. Considering evidence from fMRI studies, right-parietal alpha power increases may correspond to a deactivation of the right temporoparietal junction, reflecting an inhibition of the ventral attention network. Inhibition of this region is thought to prevent reorienting to irrelevant stimulation during goal-driven, top-down behavior, which may serve the executive function of task shielding during demanding cognitive tasks such as idea generation and mental imagery. PMID:24561034

Task Models in the Digital Ocean

ERIC Educational Resources Information Center

DiCerbo, Kristen E.

2014-01-01

The Task Model is a description of each task in a workflow. It defines attributes associated with that task. The creation of task models becomes increasingly important as the assessment tasks become more complex. Explicitly delineating the impact of task variables on the ability to collect evidence and make inferences demands thoughtfulness from…

Coarse-grained modeling of RNA 3D structure.

PubMed

Dawson, Wayne K; Maciejczyk, Maciej; Jankowska, Elzbieta J; Bujnicki, Janusz M

2016-07-01

Functional RNA molecules depend on three-dimensional (3D) structures to carry out their tasks within the cell. Understanding how these molecules interact to carry out their biological roles requires a detailed knowledge of RNA 3D structure and dynamics as well as thermodynamics, which strongly governs the folding of RNA and RNA-RNA interactions as well as a host of other interactions within the cellular environment. Experimental determination of these properties is difficult, and various computational methods have been developed to model the folding of RNA 3D structures and their interactions with other molecules. However, computational methods also have their limitations, especially when the biological effects demand computation of the dynamics beyond a few hundred nanoseconds. For the researcher confronted with such challenges, a more amenable approach is to resort to coarse-grained modeling to reduce the number of data points and computational demand to a more tractable size, while sacrificing as little critical information as possible. This review presents an introduction to the topic of coarse-grained modeling of RNA 3D structures and dynamics, covering both high- and low-resolution strategies. We discuss how physics-based approaches compare with knowledge based methods that rely on databases of information. In the course of this review, we discuss important aspects in the reasoning process behind building different models and the goals and pitfalls that can result. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Shoulder Kinematics and Spatial Pattern of Trapezius Electromyographic Activity in Real and Virtual Environments

PubMed Central

Samani, Afshin; Pontonnier, Charles; Dumont, Georges; Madeleine, Pascal

2015-01-01

The design of an industrial workstation tends to include ergonomic assessment steps based on a digital mock-up and a virtual reality setup. Lack of interaction and system fidelity is often reported as a main issue in such virtual reality applications. This limitation is a crucial issue as thorough ergonomic analysis is required for an investigation of the biomechanics. In the current study, we investigated the biomechanical responses of the shoulder joint in a simulated assembly task for comparison with the biomechanical responses in virtual environments. Sixteen male healthy novice subjects performed the task on three different platforms: real (RE), virtual (VE), and virtual environment with force feedback (VEF) with low and high precision demands. The subjects repeated the task 12 times (i.e., 12 cycles). High density electromyography from the upper trapezius and rotation angles of the shoulder joint were recorded and split into the cycles. The angular trajectories and velocity profiles of the shoulder joint angles over a cycle were computed in 3D. The inter-subject similarity in terms of normalized mutual information on kinematics and electromyography was investigated. Compared with RE the task in VE and VEF was characterized by lower kinematic maxima. The inter-subject similarity in RE compared with intra-subject similarity across the platforms was lower in terms of movement trajectories and greater in terms of trapezius muscle activation. The precision demand resulted in lower inter- and intra-subject similarity across platforms. The proposed approach identifies biomechanical differences in the shoulder joint in both VE and VEF compared with the RE platform, but these differences are less marked in VE mostly due to technical limitations of co-localizing the force feedback system in the VEF platform. PMID:25768123

Motor Variability during Sustained Contractions Increases with Cognitive Demand in Older Adults

PubMed Central

Vanden Noven, Marnie L.; Pereira, Hugo M.; Yoon, Tejin; Stevens, Alyssa A.; Nielson, Kristy A.; Hunter, Sandra K.

2014-01-01

To expose cortical involvement in age-related changes in motor performance, we compared steadiness (force fluctuations) and fatigability of submaximal isometric contractions with the ankle dorsiflexor muscles in older and young adults and with varying levels of cognitive demand imposed. Sixteen young (20.4 ± 2.1 year: 8 men, 9 women) and 17 older adults (68.8 ± 4.4 years: 9 men, 8 women) attended three sessions and performed a 40 s isometric contraction at 5% maximal voluntary contraction (MVC) force followed by an isometric contraction at 30% MVC until task failure. The cognitive demand required during the submaximal contractions in each session differed as follows: (1) high-cognitive demand session where difficult mental math was imposed (counting backward by 13 from a 4-digit number); (2) low-cognitive demand session which involved simple mental math (counting backward by 1); and (3) control session with no mental math. Anxiety was elevated during the high-cognitive demand session compared with other sessions for both age groups but more so for the older adults than young adults (p  < 0.05). Older adults had larger force fluctuations than young adults during: (1) the 5% MVC task as cognitive demand increased (p  = 0.007), and (2) the fatiguing contraction for all sessions (p  = 0.002). Time to task failure did not differ between sessions or age groups (p  > 0.05), but the variability between sessions (standard deviation of three sessions) was greater for older adults than young (2.02 ± 1.05 vs. 1.25 ± 0.51 min, p  < 0.05). Thus, variability in lower limb motor performance for low- and moderate-force isometric tasks increased with age and was exacerbated when cognitive demand was imposed, and may be related to modulation of synergist and antagonist muscles and an altered neural strategy with age originating from central sources. These data have significant implications for cognitively demanding low-force motor tasks that are relevant to functional and ergonomic in an aging workforce. PMID:24904410

Brain biomarkers based assessment of cognitive workload in pilots under various task demands.

PubMed

Gentili, Rodolphe J; Rietschel, Jeremy C; Jaquess, Kyle J; Lo, Li-Chuan; Prevost, Michael; Miller, Matt W; Mohler, Jessica M; Oh, Hyuk; Tan, Ying Ying; Hatfield, Bradley D

2014-01-01

Cognitive workload is an important element of cognitive-motor performance such as that exhibited during the piloting of an aircraft. Namely, an increase in task demands on the pilot can elevate cognitive information processing and, thus, the risk of human error. As such, there is a need to develop methods that reliably assess mental workload in pilots within operational settings. The present study contributes to this research goal by identifying physiological and brain biomarkers of cognitive workload and attentional reserve during a simulated aircraft piloting task under three progressive levels of challenge. A newly developed experimental method was employed by which electroencephalography (EEG) was acquired via a dry (i.e., gel-free sensors) system using few scalp sites. Self-reported responses to surveys and piloting performance indicators were analyzed. The findings revealed that as the challenge (task demands) increased, the perceived mental load increased, attentional reserve was attenuated, and task performance decreased. Such an increase in task demands was also reflected by changes in heart rate variability (HRV), as well as in the amplitude of the P300 component of event-related potentials to auditory probes, and in the spectral power of specific EEG frequency bands. This work provides a first step towards a long-term goal to develop a composite system of biomarkers for real-time cognitive workload assessment and state assessment of pilots in operational settings.

Getting to the Root of Fine Motor Skill Performance in Dentistry: Brain Activity During Dental Tasks in a Virtual Reality Haptic Simulation

PubMed Central

Bridges, Susan M; Zhu, Frank; Leung, W Keung; Burrow, Michael F; Poolton, Jamie; Masters, Rich SW

2017-01-01

Background There is little evidence considering the relationship between movement-specific reinvestment (a dimension of personality which refers to the propensity for individuals to consciously monitor and control their movements) and working memory during motor skill performance. Functional near-infrared spectroscopy (fNIRS) measuring oxyhemoglobin demands in the frontal cortex during performance of virtual reality (VR) psychomotor tasks can be used to examine this research gap. Objective The aim of this study was to determine the potential relationship between the propensity to reinvest and blood flow to the dorsolateral prefrontal cortices of the brain. A secondary aim was to determine the propensity to reinvest and performance during 2 dental tasks carried out using haptic VR simulators. Methods We used fNIRS to assess oxygen demands in 24 undergraduate dental students during 2 dental tasks (clinical, nonclinical) on a VR haptic simulator. We used the Movement-Specific Reinvestment Scale questionnaire to assess the students’ propensity to reinvest. Results Students with a high propensity for movement-specific reinvestment displayed significantly greater oxyhemoglobin demands in an area associated with working memory during the nonclinical task (Spearman correlation, rs=.49, P=.03). Conclusions This small-scale study suggests that neurophysiological differences are evident between high and low reinvesters during a dental VR task in terms of oxyhemoglobin demands in an area associated with working memory. PMID:29233801

False-belief understanding in frontotemporal dementia and Alzheimer's disease.

PubMed

Fernandez-Duque, Diego; Baird, Jodie A; Black, Sandra E

2009-05-01

The ability to understand other people's behavior in terms of mental states, such as beliefs, desires, and intentions, is central to social interaction. It has been argued that the interpersonal problems of patients with behavioral variant of frontotemporal dementia (FTD-b) are due to a dysfunction of that system. We used first- and second-order false-belief tasks to assess theory-of-mind reasoning in a group of patients with FTD-b and a cognitively matched group of patients with Alzheimer's disease (AD). Both patient groups were equally impaired relative to a healthy elderly group in the cognitively demanding second-order false-belief tasks, revealing that cognitive demands are an important factor in false-belief task performance. Both patient groups reached ceiling performance in the first-order false-belief tasks with minimal cognitive demands, despite the striking difference in their social graces. These results suggest that a conceptual deficit in theory of mind-as measured by the false-belief task-is not at the core of the differences between FTD-b and AD.

Automatic-heuristic and executive-analytic processing during reasoning: Chronometric and dual-task considerations.

PubMed

De Neys, Wim

2006-06-01

Human reasoning has been shown to overly rely on intuitive, heuristic processing instead of a more demanding analytic inference process. Four experiments tested the central claim of current dual-process theories that analytic operations involve time-consuming executive processing whereas the heuristic system would operate automatically. Participants solved conjunction fallacy problems and indicative and deontic selection tasks. Experiment 1 established that making correct analytic inferences demanded more processing time than did making heuristic inferences. Experiment 2 showed that burdening the executive resources with an attention-demanding secondary task decreased correct, analytic responding and boosted the rate of conjunction fallacies and indicative matching card selections. Results were replicated in Experiments 3 and 4 with a different secondary-task procedure. Involvement of executive resources for the deontic selection task was less clear. Findings validate basic processing assumptions of the dual-process framework and complete the correlational research programme of K. E. Stanovich and R. F. West (2000).

Predicting physiological capacity of human load carriage - a review.

PubMed

Drain, Jace; Billing, Daniel; Neesham-Smith, Daniel; Aisbett, Brad

2016-01-01

This review article aims to evaluate a proposed maximum acceptable work duration model for load carriage tasks. It is contended that this concept has particular relevance to physically demanding occupations such as military and firefighting. Personnel in these occupations are often required to perform very physically demanding tasks, over varying time periods, often involving load carriage. Previous research has investigated concepts related to physiological workload limits in occupational settings (e.g. industrial). Evidence suggests however, that existing (unloaded) workload guidelines are not appropriate for load carriage tasks. The utility of this model warrants further work to enable prediction of load carriage durations across a range of functional workloads for physically demanding occupations. If the maximum duration for which personnel can physiologically sustain a load carriage task could be accurately predicted, commanders and supervisors could better plan for and manage tasks to ensure operational imperatives were met whilst minimising health risks for their workers. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Demands on Finite Cognitive Capacity Cause Infants' Perseverative Errors

ERIC Educational Resources Information Center

Berger, Sarah E.

2004-01-01

This research unites traditionally disparate developmental domains--cognition and locomotion--to examine the classic cognitive issue of the development of inhibition in infancy. In 2 locomotor A-not-B tasks, 13-month-old walking infants inhibited a prepotent response under low task demands (walking on flat ground), but perseverated under increased…

The Language of Children with Spina Bifida and Hydrocephalus: Meeting Task Demands and Mastering Syntax.

ERIC Educational Resources Information Center

Byrne, Karen; And Others

1990-01-01

Linguistic performance of 7 children (mean age=68 months) with spina bifida, hydrocephalus, and average intelligence was evaluated. Subjects dealt with the semantic-pragmatic requirements of linguistically posed problems in an age-appropriate manner. Performance declined as task demands increased but no more than performance of nondisabled…

Demands and Tasks of Intercultural School Development: Group Discussions with Experts about Intercultural School Development

ERIC Educational Resources Information Center

Syring, Marcus; Tillmann, Teresa; Sacher, Nicole; Weiß, Sabine; Kiel, Ewald

2018-01-01

The present study is aimed at identifying demands and tasks that are considered important by experts in the field of interculturalism for the successful development of schools. Although different theoretical models about intercultural school development, incorporating various conditions and dimensions, have already been suggested, gaps in research…

Computer vision syndrome in presbyopia and beginning presbyopia: effects of spectacle lens type.

PubMed

Jaschinski, Wolfgang; König, Mirjam; Mekontso, Tiofil M; Ohlendorf, Arne; Welscher, Monique

2015-05-01

This office field study investigated the effects of different types of spectacle lenses habitually worn by computer users with presbyopia and in the beginning stages of presbyopia. Computer vision syndrome was assessed through reported complaints and ergonomic conditions. A questionnaire regarding the type of habitually worn near-vision lenses at the workplace, visual conditions and the levels of different types of complaints was administered to 175 participants aged 35 years and older (mean ± SD: 52.0 ± 6.7 years). Statistical factor analysis identified five specific aspects of the complaints. Workplace conditions were analysed based on photographs taken in typical working conditions. In the subgroup of 25 users between the ages of 36 and 57 years (mean 44 ± 5 years), who wore distance-vision lenses and performed more demanding occupational tasks, the reported extents of 'ocular strain', 'musculoskeletal strain' and 'headache' increased with the daily duration of computer work and explained up to 44 per cent of the variance (rs = 0.66). In the other subgroups, this effect was smaller, while in the complete sample (n = 175), this correlation was approximately rs = 0.2. The subgroup of 85 general-purpose progressive lens users (mean age 54 years) adopted head inclinations that were approximately seven degrees more elevated than those of the subgroups with single vision lenses. The present questionnaire was able to assess the complaints of computer users depending on the type of spectacle lenses worn. A missing near-vision addition among participants in the early stages of presbyopia was identified as a risk factor for complaints among those with longer daily durations of demanding computer work. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

User Experience May be Producing Greater Heart Rate Variability than Motor Imagery Related Control Tasks during the User-System Adaptation in Brain-Computer Interfaces

PubMed Central

Alonso-Valerdi, Luz M.; Gutiérrez-Begovich, David A.; Argüello-García, Janet; Sepulveda, Francisco; Ramírez-Mendoza, Ricardo A.

2016-01-01

Brain-computer interface (BCI) is technology that is developing fast, but it remains inaccurate, unreliable and slow due to the difficulty to obtain precise information from the brain. Consequently, the involvement of other biosignals to decode the user control tasks has risen in importance. A traditional way to operate a BCI system is via motor imagery (MI) tasks. As imaginary movements activate similar cortical structures and vegetative mechanisms as a voluntary movement does, heart rate variability (HRV) has been proposed as a parameter to improve the detection of MI related control tasks. However, HR is very susceptible to body needs and environmental demands, and as BCI systems require high levels of attention, perceptual processing and mental workload, it is important to assess the practical effectiveness of HRV. The present study aimed to determine if brain and heart electrical signals (HRV) are modulated by MI activity used to control a BCI system, or if HRV is modulated by the user perceptions and responses that result from the operation of a BCI system (i.e., user experience). For this purpose, a database of 11 participants who were exposed to eight different situations was used. The sensory-cognitive load (intake and rejection tasks) was controlled in those situations. Two electrophysiological signals were utilized: electroencephalography and electrocardiography. From those biosignals, event-related (de-)synchronization maps and event-related HR changes were respectively estimated. The maps and the HR changes were cross-correlated in order to verify if both biosignals were modulated due to MI activity. The results suggest that HR varies according to the experience undergone by the user in a BCI working environment, and not because of the MI activity used to operate the system. PMID:27458384

Will the future of knowledge work automation transform personalized medicine?

PubMed

Naik, Gauri; Bhide, Sanika S

2014-09-01

Today, we live in a world of 'information overload' which demands high level of knowledge-based work. However, advances in computer hardware and software have opened possibilities to automate 'routine cognitive tasks' for knowledge processing. Engineering intelligent software systems that can process large data sets using unstructured commands and subtle judgments and have the ability to learn 'on the fly' are a significant step towards automation of knowledge work. The applications of this technology for high throughput genomic analysis, database updating, reporting clinically significant variants, and diagnostic imaging purposes are explored using case studies.

Solution conformation of carbohydrates: a view by using NMR assisted by modeling.

PubMed

Díaz, Dolores; Canales-Mayordomo, Angeles; Cañada, F Javier; Jiménez-Barbero, Jesús

2015-01-01

Structural elucidation of complex carbohydrates in solution is not a trivial task. From the NMR view point, the limited chemical shift dispersion of sugar NMR spectra demands the combination of a variety of NMR techniques as well as the employment of molecular modeling methods. Herein, a general protocol for assignment of resonances and determination of inter-proton distances within the saccharides by homonuclear and heteronuclear experiments (i.e., (1)H and (13)C) is described. In addition, several computational tools and procedures for getting a final ensemble of geometries that represent the structure in solution are presented.

Metacognitive evaluation in the avoidance of demand.

PubMed

Dunn, Timothy L; Lutes, David J C; Risko, Evan F

2016-09-01

In the current set of experiments our goal was to test the hypothesis that individuals avoid courses of action based on a kind of metacognitive evaluation of demand in a Demand Selection Task (DST). Individuals in Experiment 1 completed a DST utilizing visual stimuli known to yield a dissociation between performance and perceived demand. Patterns of demand avoidance followed that of perceived demand. Experiment 2 provided a replication of the aforementioned results, in addition to demonstrating a second dissociation between a peripheral physiological measure of demand (i.e., blink rates) and demand avoidance. Experiment 3 directly tested the assumption that individuals make use of a general metacognitive evaluation of task demand during selections. A DST was utilized in a forced-choice paradigm that required individuals to either select the most effortful, time demanding, or least accurate of 2 choices. Patterns of selections were similar across all rating dimensions, lending credit to this notion. Findings are discussed within a metacognitive framework of demand avoidance and contrasted to current theories. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Perceived task complexity of trunk stability exercises.

PubMed

McPhee, Megan; Tucker, Kylie J; Wan, Alan; MacDonald, David A

2017-02-01

Perceived task complexity can impact participation in an exercise programme and the level of skill acquisition resulting from participation. Although trunk stability exercises are commonly included in the management of people with low back pain, potential differences in perceived task complexity between those exercises have not been investigated previously. To investigate the perceived task complexity following first time instruction of two common stability exercises: the abdominal brace and abdominal hollow. Cross-sectional. Twenty-four naïve healthy participants received instruction in the performance of an abdominal brace and an abdominal hollow with feedback. Participants rated their perceived task complexity (mental, physical, and temporal demand, performance, effort, frustration) for each exercise on the NASA-Task Load Index. The abdominal hollow was associated with higher perceived mental demand than the abdominal brace (p = 0.01), and required more time to learn (p < 0.01). The abdominal brace was associated with greater mental demand and frustration when performed after the abdominal hollow than before. This study has provided the first evidence for differences in perceived task complexity between two commonly used trunk stability exercises. Those differences in perceived task complexity may influence the selection of exercises intended to enhance the robustness of spinal stability. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Novel Eye-Tracking Method to Assess Attention Allocation in Individuals with and without Aphasia Using a Dual-Task Paradigm

PubMed Central

Heuer, Sabine; Hallowell, Brooke

2015-01-01

Numerous authors report that people with aphasia have greater difficulty allocating attention than people without neurological disorders. Studying how attention deficits contribute to language deficits is important. However, existing methods for indexing attention allocation in people with aphasia pose serious methodological challenges. Eye-tracking methods have great potential to address such challenges. We developed and assessed the validity of a new dual-task method incorporating eye tracking to assess attention allocation. Twenty-six adults with aphasia and 33 control participants completed auditory sentence comprehension and visual search tasks. To test whether the new method validly indexes well-documented patterns in attention allocation, demands were manipulated by varying task complexity in single- and dual-task conditions. Differences in attention allocation were indexed via eye-tracking measures. For all participants significant increases in attention allocation demands were observed from single- to dual-task conditions and from simple to complex stimuli. Individuals with aphasia had greater difficulty allocating attention with greater task demands. Relationships between eye-tracking indices of comprehension during single and dual tasks and standardized testing were examined. Results support the validity of the novel eye-tracking method for assessing attention allocation in people with and without aphasia. Clinical and research implications are discussed. PMID:25913549

The Validity of Functional Near-Infrared Spectroscopy Recordings of Visuospatial Working Memory Processes in Humans.

PubMed

Witmer, Joëlle S; Aeschlimann, Eva A; Metz, Andreas J; Troche, Stefan J; Rammsayer, Thomas H

2018-04-05

Functional near infrared spectroscopy (fNIRS) is increasingly used for investigating cognitive processes. To provide converging evidence for the validity of fNIRS recordings in cognitive neuroscience, we investigated functional activation in the frontal cortex in 43 participants during the processing of a visuospatial working memory (WM) task and a sensory duration discrimination (DD) task functionally unrelated to WM. To distinguish WM-related processes from a general effect of increased task demand, we applied an adaptive approach, which ensured that subjective task demand was virtually identical for all individuals and across both tasks. Our specified region of interest covered Brodmann Area 8 of the left hemisphere, known for its important role in the execution of WM processes. Functional activation, as indicated by an increase of oxygenated and a decrease of deoxygenated hemoglobin, was shown for the WM task, but not in the DD task. The overall pattern of results indicated that hemodynamic responses recorded by fNIRS are sensitive to specific visuospatial WM capacity-related processes and do not reflect a general effect of increased task demand. In addition, the finding that no such functional activation could be shown for participants with far above-average mental ability suggested different cognitive processes adopted by this latter group.

The Validity of Functional Near-Infrared Spectroscopy Recordings of Visuospatial Working Memory Processes in Humans

PubMed Central

Witmer, Joëlle S.; Aeschlimann, Eva A.; Metz, Andreas J.; Rammsayer, Thomas H.

2018-01-01

Functional near infrared spectroscopy (fNIRS) is increasingly used for investigating cognitive processes. To provide converging evidence for the validity of fNIRS recordings in cognitive neuroscience, we investigated functional activation in the frontal cortex in 43 participants during the processing of a visuospatial working memory (WM) task and a sensory duration discrimination (DD) task functionally unrelated to WM. To distinguish WM-related processes from a general effect of increased task demand, we applied an adaptive approach, which ensured that subjective task demand was virtually identical for all individuals and across both tasks. Our specified region of interest covered Brodmann Area 8 of the left hemisphere, known for its important role in the execution of WM processes. Functional activation, as indicated by an increase of oxygenated and a decrease of deoxygenated hemoglobin, was shown for the WM task, but not in the DD task. The overall pattern of results indicated that hemodynamic responses recorded by fNIRS are sensitive to specific visuospatial WM capacity-related processes and do not reflect a general effect of increased task demand. In addition, the finding that no such functional activation could be shown for participants with far above-average mental ability suggested different cognitive processes adopted by this latter group. PMID:29621179

Salivary α-amylase reflects change in attentional demands during postural control: comparison with probe reaction time.

PubMed

Akizuki, Kazunori; Ohashi, Yukari

2014-12-01

The influence of attention on postural control and the relationship between attention and falling has been reported in previous studies. Although a dual-task procedure is commonly used to measure attentional demand, such procedures are affected by allocation policy, which is a mental strategy to divide attention between simultaneous tasks. Therefore, we examined the effectiveness of salivary α-amylase, which is a physiological method for measuring attentional demand during postural control. Sixteen healthy participants performed a postural-control task using the Balance System, which is a device that can be calibrated to a specific stability level ("Level 1 = least stable" to "Level 8 = most stable"). Levels 1, 2, and 3 were used for this study. Dependent variables measured were overall stability index, which represents the variance of platform displacement in degrees from a horizontal plane; probe reaction time, which was measured using a sound stimulator and recorder; and salivary α-amylase, which was measured using a portable salivary amylase analyzer. As stability level of the test task decreased, both stability index and probe reaction time significantly increased. In addition, we identified a positive moderate correlation between probe reaction time and salivary α-amylase. Our results suggest that salivary α-amylase and probe reaction time reflect the change in attentional demands during a postural-control task and that salivary α-amylase may be an effective tool for evaluating attentional demands during postural control because it is noninvasive and simple to perform.

Task relevance induces momentary changes in the functional visual field during reading.

PubMed

Kaakinen, Johanna K; Hyönä, Jukka

2014-02-01

In the research reported here, we examined whether task demands can induce momentary tunnel vision during reading. More specifically, we examined whether the size of the functional visual field depends on task relevance. Forty participants read an expository text with a specific task in mind while their eye movements were recorded. A display-change paradigm with random-letter strings as preview masks was used to study the size of the functional visual field within sentences that contained task-relevant and task-irrelevant information. The results showed that orthographic parafoveal-on-foveal effects and preview benefits were observed for words within task-irrelevant but not task-relevant sentences. The results indicate that the size of the functional visual field is flexible and depends on the momentary processing demands of a reading task. The higher cognitive processing requirements experienced when reading task-relevant text rather than task-irrelevant text induce momentary tunnel vision, which narrows the functional visual field.

Conscious Vision Proceeds from Global to Local Content in Goal-Directed Tasks and Spontaneous Vision.

PubMed

Campana, Florence; Rebollo, Ignacio; Urai, Anne; Wyart, Valentin; Tallon-Baudry, Catherine

2016-05-11

The reverse hierarchy theory (Hochstein and Ahissar, 2002) makes strong, but so far untested, predictions on conscious vision. In this theory, local details encoded in lower-order visual areas are unconsciously processed before being automatically and rapidly combined into global information in higher-order visual areas, where conscious percepts emerge. Contingent on current goals, local details can afterward be consciously retrieved. This model therefore predicts that (1) global information is perceived faster than local details, (2) global information is computed regardless of task demands during early visual processing, and (3) spontaneous vision is dominated by global percepts. We designed novel textured stimuli that are, as opposed to the classic Navon's letters, truly hierarchical (i.e., where global information is solely defined by local information but where local and global orientations can still be manipulated separately). In line with the predictions, observers were systematically faster reporting global than local properties of those stimuli. Second, global information could be decoded from magneto-encephalographic data during early visual processing regardless of task demands. Last, spontaneous subjective reports were dominated by global information and the frequency and speed of spontaneous global perception correlated with the accuracy and speed in the global task. No such correlation was observed for local information. We therefore show that information at different levels of the visual hierarchy is not equally likely to become conscious; rather, conscious percepts emerge preferentially at a global level. We further show that spontaneous reports can be reliable and are tightly linked to objective performance at the global level. Is information encoded at different levels of the visual system (local details in low-level areas vs global shapes in high-level areas) equally likely to become conscious? We designed new hierarchical stimuli and provide the first empirical evidence based on behavioral and MEG data that global information encoded at high levels of the visual hierarchy dominates perception. This result held both in the presence and in the absence of task demands. The preferential emergence of percepts at high levels can account for two properties of conscious vision, namely, the dominance of global percepts and the feeling of visual richness reported independently of the perception of local details. Copyright © 2016 the authors 0270-6474/16/365200-14$15.00/0.

Sound segregation via embedded repetition is robust to inattention.

PubMed

Masutomi, Keiko; Barascud, Nicolas; Kashino, Makio; McDermott, Josh H; Chait, Maria

2016-03-01

The segregation of sound sources from the mixture of sounds that enters the ear is a core capacity of human hearing, but the extent to which this process is dependent on attention remains unclear. This study investigated the effect of attention on the ability to segregate sounds via repetition. We utilized a dual task design in which stimuli to be segregated were presented along with stimuli for a "decoy" task that required continuous monitoring. The task to assess segregation presented a target sound 10 times in a row, each time concurrent with a different distractor sound. McDermott, Wrobleski, and Oxenham (2011) demonstrated that repetition causes the target sound to be segregated from the distractors. Segregation was queried by asking listeners whether a subsequent probe sound was identical to the target. A control task presented similar stimuli but probed discrimination without engaging segregation processes. We present results from 3 different decoy tasks: a visual multiple object tracking task, a rapid serial visual presentation (RSVP) digit encoding task, and a demanding auditory monitoring task. Load was manipulated by using high- and low-demand versions of each decoy task. The data provide converging evidence of a small effect of attention that is nonspecific, in that it affected the segregation and control tasks to a similar extent. In all cases, segregation performance remained high despite the presence of a concurrent, objectively demanding decoy task. The results suggest that repetition-based segregation is robust to inattention. (c) 2016 APA, all rights reserved).

Recalibration of the Multisensory Temporal Window of Integration Results from Changing Task Demands

PubMed Central

Mégevand, Pierre; Molholm, Sophie; Nayak, Ashabari; Foxe, John J.

2013-01-01

The notion of the temporal window of integration, when applied in a multisensory context, refers to the breadth of the interval across which the brain perceives two stimuli from different sensory modalities as synchronous. It maintains a unitary perception of multisensory events despite physical and biophysical timing differences between the senses. The boundaries of the window can be influenced by attention and past sensory experience. Here we examined whether task demands could also influence the multisensory temporal window of integration. We varied the stimulus onset asynchrony between simple, short-lasting auditory and visual stimuli while participants performed two tasks in separate blocks: a temporal order judgment task that required the discrimination of subtle auditory-visual asynchronies, and a reaction time task to the first incoming stimulus irrespective of its sensory modality. We defined the temporal window of integration as the range of stimulus onset asynchronies where performance was below 75% in the temporal order judgment task, as well as the range of stimulus onset asynchronies where responses showed multisensory facilitation (race model violation) in the reaction time task. In 5 of 11 participants, we observed audio-visual stimulus onset asynchronies where reaction time was significantly accelerated (indicating successful integration in this task) while performance was accurate in the temporal order judgment task (indicating successful segregation in that task). This dissociation suggests that in some participants, the boundaries of the temporal window of integration can adaptively recalibrate in order to optimize performance according to specific task demands. PMID:23951203

Effects of Working Memory Demand on Neural Mechanisms of Motor Response Selection and Control

PubMed Central

Barber, Anita D.; Caffo, Brian S.; Pekar, James J.; Mostofsky, Stewart H.

2013-01-01

Inhibitory control commonly recruits a number of frontal regions: pre-supplementary motor area (pre-SMA), frontal eye fields (FEFs), and right-lateralized posterior inferior frontal gyrus (IFG), dorsal anterior insula (DAI), dorsolateral prefrontal cortex (DLPFC), and inferior frontal junction (IFJ). These regions may directly implement inhibitory motor control or may be more generally involved in executive control functions. Two go/no-go tasks were used to distinguish regions specifically recruited for inhibition from those that additionally show increased activity with working memory demand. The pre-SMA and IFG were recruited for inhibition in both tasks and did not have greater activation for working memory demand on no-go trials, consistent with a role in inhibitory control. Activation in pre-SMA also responded to response selection demand and was increased with working memory on go trials specifically. The bilateral FEF and right DAI were commonly active for no-go trials. The FEF was also recruited to a greater degree with working memory demand on go trials and may bias top–down information when stimulus–response mappings change. The DAI, additionally responded to increased working memory demand on both go and no-go trials and may be involved in accessing sustained task information, alerting, or autonomic changes when cognitive demands increase. DLPFC activation was consistent with a role in working memory retrieval on both go and no-go trials. The inferior frontal junction, on the other hand, had greater activation with working memory specifically for no-go trials and may detect salient stimuli when the task requires frequent updating of working memory representations. PMID:23530923

Auditory temporal preparation induced by rhythmic cues during concurrent auditory working memory tasks.

PubMed

Cutanda, Diana; Correa, Ángel; Sanabria, Daniel

2015-06-01

The present study investigated whether participants can develop temporal preparation driven by auditory isochronous rhythms when concurrently performing an auditory working memory (WM) task. In Experiment 1, participants had to respond to an auditory target presented after a regular or an irregular sequence of auditory stimuli while concurrently performing a Sternberg-type WM task. Results showed that participants responded faster after regular compared with irregular rhythms and that this effect was not affected by WM load; however, the lack of a significant main effect of WM load made it difficult to draw any conclusion regarding the influence of the dual-task manipulation in Experiment 1. In order to enhance dual-task interference, Experiment 2 combined the auditory rhythm procedure with an auditory N-Back task, which required WM updating (monitoring and coding of the information) and was presumably more demanding than the mere rehearsal of the WM task used in Experiment 1. Results now clearly showed dual-task interference effects (slower reaction times [RTs] in the high- vs. the low-load condition). However, such interference did not affect temporal preparation induced by rhythms, with faster RTs after regular than after irregular sequences in the high-load and low-load conditions. These results revealed that secondary tasks demanding memory updating, relative to tasks just demanding rehearsal, produced larger interference effects on overall RTs in the auditory rhythm task. Nevertheless, rhythm regularity exerted a strong temporal preparation effect that survived the interference of the WM task even when both tasks competed for processing resources within the auditory modality. (c) 2015 APA, all rights reserved).

A new computational account of cognitive control over reinforcement-based decision-making: Modeling of a probabilistic learning task.

PubMed

Zendehrouh, Sareh

2015-11-01

Recent work on decision-making field offers an account of dual-system theory for decision-making process. This theory holds that this process is conducted by two main controllers: a goal-directed system and a habitual system. In the reinforcement learning (RL) domain, the habitual behaviors are connected with model-free methods, in which appropriate actions are learned through trial-and-error experiences. However, goal-directed behaviors are associated with model-based methods of RL, in which actions are selected using a model of the environment. Studies on cognitive control also suggest that during processes like decision-making, some cortical and subcortical structures work in concert to monitor the consequences of decisions and to adjust control according to current task demands. Here a computational model is presented based on dual system theory and cognitive control perspective of decision-making. The proposed model is used to simulate human performance on a variant of probabilistic learning task. The basic proposal is that the brain implements a dual controller, while an accompanying monitoring system detects some kinds of conflict including a hypothetical cost-conflict one. The simulation results address existing theories about two event-related potentials, namely error related negativity (ERN) and feedback related negativity (FRN), and explore the best account of them. Based on the results, some testable predictions are also presented. Copyright © 2015 Elsevier Ltd. All rights reserved.

LHCbDIRAC as Apache Mesos microservices

NASA Astrophysics Data System (ADS)

Haen, Christophe; Couturier, Benjamin

2017-10-01

The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and run on virtual machines (VM) or bare metal hardware. Due to the increased workload, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. Apache Mesos is a cluster manager which aims at abstracting heterogeneous physical resources on which various tasks can be distributed thanks to so called “frameworks” The Marathon framework is suitable for long running tasks such as the DIRAC services, while the Chronos framework meets the needs of cron-like tasks like the DIRAC agents. A combination of the service discovery tool Consul together with HAProxy allows to expose the running containers to the outside world while hiding their dynamic placements. Such an architecture brings a greater flexibility in the deployment of LHCbDirac services, allowing for easier deployment maintenance and scaling of services on demand (e..g LHCbDirac relies on 138 services and 116 agents). Higher reliability is also easier, as clustering is part of the toolset, which allows constraints on the location of the services. This paper describes the investigations carried out to package the LHCbDIRAC and DIRAC components into Docker containers and orchestrate them using the previously described set of tools.

Integrating Markets to Bridge Supply and Demand for Knowledge Intensive Tasks

NASA Astrophysics Data System (ADS)

Overbeek, Sietse; Janssen, Marijn; van Bommel, Patrick

The advent of the knowledge-based economy has underlined the importance of intellectual capital that is possessed by knowledge intensive organizations. Three general observations of knowledge intensive work produced by actors working in such organizations served as the basis for the initiation of this research. First, knowledge intensive tasks become increasingly complex. Second, actors that perform such tasks experience an increase in cognitive load. Third, the desired quality of task performance and the produced task results are at stake due to the aforementioned two developments. In this research we investigate how supply and demand of intangible assets such as knowledge, cognitive characteristics, and quality factors can be matched based on market mechanisms.

Fighter pilots' heart rate, heart rate variation and performance during an instrument flight rules proficiency test.

PubMed

Mansikka, Heikki; Virtanen, Kai; Harris, Don; Simola, Petteri

2016-09-01

Increased task demand will increase the pilot mental workload (PMWL). When PMWL is increased, mental overload may occur resulting in degraded performance. During pilots' instrument flight rules (IFR) proficiency test, PMWL is typically not measured. Therefore, little is known about workload during the proficiency test and pilots' potential to cope with higher task demands than those experienced during the test. In this study, fighter pilots' performance and PMWL was measured during a real IFR proficiency test in an F/A-18 simulator. PMWL was measured using heart rate (HR) and heart rate variation (HRV). Performance was rated using Finnish Air Force's official rating scales. Results indicated that HR and HRV differentiate varying task demands in situations where variations in performance are insignificant. It was concluded that during a proficiency test, PMWL should be measured together with the task performance measurement. Copyright © 2016 Elsevier Ltd. All rights reserved.

Task demand influences relationships among sex, clustering strategy, and recall: 16-word versus 9-word list learning tests.

PubMed

Sunderaraman, Preeti; Blumen, Helena M; DeMatteo, David; Apa, Zoltan L; Cosentino, Stephanie

2013-06-01

We compared the relationships among sex, clustering strategy, and recall across different task demands using the 16-word California Verbal Learning Test-Second Edition (CVLT-II) and the 9-word Philadelphia (repeatable) Verbal Learning Test (PrVLT). Women generally score higher than men on verbal memory tasks, possibly because women tend to use semantic clustering. This sex difference has been established via word-list learning tests such as the CVLT-II. In a retrospective between-group study, we compared how 2 separate groups of cognitively healthy older adults performed on a longer and a shorter verbal learning test. The group completing the CVLT-II had 36 women and 26 men; the group completing the PrVLT had 27 women and 21 men. Overall, multiple regression analyses revealed that semantic clustering was significantly associated with total recall on both tests' lists (P<0.001). Sex differences in recall and semantic clustering diminished with the shorter PrVLT word list. Semantic clustering uniquely influenced recall on both the longer and shorter word lists. However, serial clustering and sex influenced recall depending on the length of the word list (ie, the task demand). These findings suggest a complex nonlinear relationship among verbal memory, clustering strategies, and task demand.

Task Demand Influences Relationships Among Sex, Clustering Strategy, and Recall: 16-Word Versus 9-Word List Learning Tests

PubMed Central

Sunderaraman, Preeti; Blumen, Helena M.; DeMatteo, David; Apa, Zoltan; Cosentino, Stephanie

2013-01-01

Objective We compared the relationships among sex, clustering strategy, and recall across different task demands using the 16-word California Verbal Learning Test–Second Edition (CVLT-II) and the 9-word Philadelphia (repeatable) Verbal Learning Test (PrVLT). Background Women generally score higher than men on verbal memory tasks, possibly because women tend to use semantic clustering. This sex difference has been established via word-list learning tests such as the CVLT-II. Methods In a retrospective between-group study, we compared how 2 separate groups of cognitively healthy older adults performed on a longer and a shorter verbal learning test. The group completing the CVLT-II had 36 women and 26 men; the group completing the PrVLT had 27 women and 21 men. Results Overall, multiple regression analyses revealed that semantic clustering was significantly associated with total recall on both tests’ lists (P < 0.001). Sex differences in recall and semantic clustering diminished with the shorter PrVLT word list. Conclusions Semantic clustering uniquely influenced recall on both the longer and shorter word lists. However, serial clustering and sex influenced recall depending on the length of the word list (ie, the task demand). These findings suggest a complex nonlinear relationship among verbal memory, clustering strategies, and task demand. PMID:23812171

Stress in nonregular work arrangements: A longitudinal study of task- and employment-related aspects of stress.

PubMed

Vahle-Hinz, Tim

2016-10-01

In nonregular forms of employment, such as fixed-term or temporary agency work, 2 sources of stress must be distinguished: task-related stress components (e.g., time pressure) and employment-related stress components (e.g., effort to maintain employment). The present study investigated the relationship between task- and employment-related demands and resources and indicators of strain, well-being, work engagement, and self-rated performance in a sample of nonregular employed workers. Using a 2-wave longitudinal design, the results of autoregressive cross-lagged structural equation models demonstrated that time pressure, as a task-related demand, is positively related to strain and negatively related to well-being and self-rated performance. Autonomy, as a task-related resource, exhibited no significant relationships in the current study. Employment-related demands exhibited negative relationships with well-being and work engagement as well as negative and positive relationships with self-rated performance over time. Employment-related resources were primarily positive predictors of well-being and self-rated performance. Fit indices of comparative models indicated that reciprocal effect models (which enable causal and reverse effects) best fit the data. Accordingly, demands and resources predicted strain, well-being, work engagement, and self-rated performance over time and vice versa. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Individual differences in the benefits of feedback for learning.

PubMed

Kelley, Christopher M; McLaughlin, Anne Collins

2012-02-01

Research on learning from feedback has produced ambiguous guidelines for feedback design--some have advocated minimal feedback, whereas others have recommended more extensive feedback that highly supported performance. The objective of the current study was to investigate how individual differences in cognitive resources may predict feedback requirements and resolve previous conflicted findings. Cognitive resources were controlled for by comparing samples from populations with known differences, older and younger adults.To control for task demands, a simple rule-based learning task was created in which participants learned to identify fake Windows pop-ups. Pop-ups were divided into two categories--those that required fluid ability to identify and those that could be identified using crystallized intelligence. In general, results showed participants given higher feedback learned more. However, when analyzed by type of task demand, younger adults performed comparably with both levels of feedback for both cues whereas older adults benefited from increased feedbackfor fluid ability cues but from decreased feedback for crystallized ability cues. One explanation for the current findings is feedback requirements are connected to the cognitive abilities of the learner-those with higher abilities for the type of demands imposed by the task are likely to benefit from reduced feedback. We suggest the following considerations for feedback design: Incorporate learner characteristics and task demands when designing learning support via feedback.

Effective connectivity within the frontoparietal control network differentiates cognitive control and working memory.

PubMed

Harding, Ian H; Yücel, Murat; Harrison, Ben J; Pantelis, Christos; Breakspear, Michael

2015-02-01

Cognitive control and working memory rely upon a common fronto-parietal network that includes the inferior frontal junction (IFJ), dorsolateral prefrontal cortex (dlPFC), pre-supplementary motor area/dorsal anterior cingulate cortex (pSMA/dACC), and intraparietal sulcus (IPS). This network is able to flexibly adapt its function in response to changing behavioral goals, mediating a wide range of cognitive demands. Here we apply dynamic causal modeling to functional magnetic resonance imaging data to characterize task-related alterations in the strength of network interactions across distinct cognitive processes. Evidence in favor of task-related connectivity dynamics was accrued across a very large space of possible network structures. Cognitive control and working memory demands were manipulated using a factorial combination of the multi-source interference task and a verbal 2-back working memory task, respectively. Both were found to alter the sensitivity of the IFJ to perceptual information, and to increase IFJ-to-pSMA/dACC connectivity. In contrast, increased connectivity from the pSMA/dACC to the IPS, as well as from the dlPFC to the IFJ, was uniquely driven by cognitive control demands; a task-induced negative influence of the dlPFC on the pSMA/dACC was specific to working memory demands. These results reflect a system of both shared and unique context-dependent dynamics within the fronto-parietal network. Mechanisms supporting cognitive engagement, response selection, and action evaluation may be shared across cognitive domains, while dynamic updating of task and context representations within this network are potentially specific to changing demands on cognitive control. Copyright © 2014 Elsevier Inc. All rights reserved.

Performance of an attention-demanding task during treadmill walking shifts the noise qualities of step-to-step variation in step width.

PubMed

Grabiner, Mark D; Marone, Jane R; Wyatt, Marilynn; Sessoms, Pinata; Kaufman, Kenton R

2018-06-01

The fractal scaling evident in the step-to-step fluctuations of stepping-related time series reflects, to some degree, neuromotor noise. The primary purpose of this study was to determine the extent to which the fractal scaling of step width, step width and step width variability are affected by performance of an attention-demanding task. We hypothesized that the attention-demanding task would shift the structure of the step width time series toward white, uncorrelated noise. Subjects performed two 10-min treadmill walking trials, a control trial of undisturbed walking and a trial during which they performed a mental arithmetic/texting task. Motion capture data was converted to step width time series, the fractal scaling of which were determined from their power spectra. Fractal scaling decreased by 22% during the texting condition (p < 0.001) supporting the hypothesized shift toward white uncorrelated noise. Step width and step width variability increased 19% and five percent, respectively (p < 0.001). However, a stepwise discriminant analysis to which all three variables were input revealed that the control and dual task conditions were discriminated only by step width fractal scaling. The change of the fractal scaling of step width is consistent with increased cognitive demand and suggests a transition in the characteristics of the signal noise. This may reflect an important advance toward the understanding of the manner in which neuromotor noise contributes to some types of falls. However, further investigation of the repeatability of the results, the sensitivity of the results to progressive increases in cognitive load imposed by attention-demanding tasks, and the extent to which the results can be generalized to the gait of older adults seems warranted. Copyright © 2018 Elsevier B.V. All rights reserved.

Proceedings of the DoD Workload Assessment Workshop on Workload Assessment Techniques and Tools Held in Dayton Ohio on 27-28 September 1986.

DTIC Science & Technology

1987-09-15

memory task. Subjects in the experiment were required to monitor a visual display and update the status of four categories of information that changed ...Kahneman, D., 1966, Pupillary changes in two memory tasks, Psychonomic Science, 55:371-372. Casali, J. G. and Wierwille, W. W., 1982, A sensitivity...operator to deal with the demands. 3. The level of operator performance that results from the inter - action of task demands and capacity/effort

The role of attention during retrieval in working-memory span: a dual-task study.

PubMed

Healey, M Karl; Miyake, Akira

2009-04-01

We tested the hypothesis that retrieving target words in operation span (OSpan) involves attention-demanding processes. Participants completed the standard OSpan task and a modified version in which all equations preceded all target words. Recall took place under either full attention or easy versus hard divided-attention conditions. Recall suffered under divided attention with the recall decrement being greater for the hard secondary task. Moreover, secondary-task performance was disrupted more by the standard OSpan task than by the modified version with the hard secondary task showing the larger decrement. Finally, the time taken to start recalling the first word was considerably longer for the standard version than for the modified version. These results are consistent with the proposal that successful OSpan task performance in part involves the attention-demanding retrieval of targets from long-term memory.

Specificity and transfer effects in time production skill: examining the role of attention.

PubMed

Wohldmann, Erica L; Healy, Alice F; Bourne, Lyle E

2012-05-01

Two experiments examined transfer of a prospective, time production skill under conditions involving changes in concurrent task requirements. Positive transfer of the time production skill might be expected only when the attentional demands of the concurrent task were held constant from training to test. However, some positive transfer was found even when the concurrent task at retraining was made either easier or more difficult than the concurrent task learned during training. The amount and direction of transfer depended more on the pacing of the stimuli in the secondary task than on the difficulty of the secondary task, even though difficulty affects attentional demands more. These findings are consistent with the procedural reinstatement principle of skill learning, by which transfer from one task to another depends on an overlap in procedures required by the two skills.

AstroGrid-D: Grid technology for astronomical science

NASA Astrophysics Data System (ADS)

Enke, Harry; Steinmetz, Matthias; Adorf, Hans-Martin; Beck-Ratzka, Alexander; Breitling, Frank; Brüsemeister, Thomas; Carlson, Arthur; Ensslin, Torsten; Högqvist, Mikael; Nickelt, Iliya; Radke, Thomas; Reinefeld, Alexander; Reiser, Angelika; Scholl, Tobias; Spurzem, Rainer; Steinacker, Jürgen; Voges, Wolfgang; Wambsganß, Joachim; White, Steve

2011-02-01

We present status and results of AstroGrid-D, a joint effort of astrophysicists and computer scientists to employ grid technology for scientific applications. AstroGrid-D provides access to a network of distributed machines with a set of commands as well as software interfaces. It allows simple use of computer and storage facilities and to schedule or monitor compute tasks and data management. It is based on the Globus Toolkit middleware (GT4). Chapter 1 describes the context which led to the demand for advanced software solutions in Astrophysics, and we state the goals of the project. We then present characteristic astrophysical applications that have been implemented on AstroGrid-D in chapter 2. We describe simulations of different complexity, compute-intensive calculations running on multiple sites (Section 2.1), and advanced applications for specific scientific purposes (Section 2.2), such as a connection to robotic telescopes (Section 2.2.3). We can show from these examples how grid execution improves e.g. the scientific workflow. Chapter 3 explains the software tools and services that we adapted or newly developed. Section 3.1 is focused on the administrative aspects of the infrastructure, to manage users and monitor activity. Section 3.2 characterises the central components of our architecture: The AstroGrid-D information service to collect and store metadata, a file management system, the data management system, and a job manager for automatic submission of compute tasks. We summarise the successfully established infrastructure in chapter 4, concluding with our future plans to establish AstroGrid-D as a platform of modern e-Astronomy.

Optimization of tomographic reconstruction workflows on geographically distributed resources

DOE PAGES

Bicer, Tekin; Gursoy, Doga; Kettimuthu, Rajkumar; ...

2016-01-01

New technological advancements in synchrotron light sources enable data acquisitions at unprecedented levels. This emergent trend affects not only the size of the generated data but also the need for larger computational resources. Although beamline scientists and users have access to local computational resources, these are typically limited and can result in extended execution times. Applications that are based on iterative processing as in tomographic reconstruction methods require high-performance compute clusters for timely analysis of data. Here, time-sensitive analysis and processing of Advanced Photon Source data on geographically distributed resources are focused on. Two main challenges are considered: (i) modelingmore » of the performance of tomographic reconstruction workflows and (ii) transparent execution of these workflows on distributed resources. For the former, three main stages are considered: (i) data transfer between storage and computational resources, (i) wait/queue time of reconstruction jobs at compute resources, and (iii) computation of reconstruction tasks. These performance models allow evaluation and estimation of the execution time of any given iterative tomographic reconstruction workflow that runs on geographically distributed resources. For the latter challenge, a workflow management system is built, which can automate the execution of workflows and minimize the user interaction with the underlying infrastructure. The system utilizes Globus to perform secure and efficient data transfer operations. The proposed models and the workflow management system are evaluated by using three high-performance computing and two storage resources, all of which are geographically distributed. Workflows were created with different computational requirements using two compute-intensive tomographic reconstruction algorithms. Experimental evaluation shows that the proposed models and system can be used for selecting the optimum resources, which in turn can provide up to 3.13× speedup (on experimented resources). Furthermore, the error rates of the models range between 2.1 and 23.3% (considering workflow execution times), where the accuracy of the model estimations increases with higher computational demands in reconstruction tasks.« less

Optimization of tomographic reconstruction workflows on geographically distributed resources

PubMed Central

Bicer, Tekin; Gürsoy, Doǧa; Kettimuthu, Rajkumar; De Carlo, Francesco; Foster, Ian T.

2016-01-01

New technological advancements in synchrotron light sources enable data acquisitions at unprecedented levels. This emergent trend affects not only the size of the generated data but also the need for larger computational resources. Although beamline scientists and users have access to local computational resources, these are typically limited and can result in extended execution times. Applications that are based on iterative processing as in tomographic reconstruction methods require high-performance compute clusters for timely analysis of data. Here, time-sensitive analysis and processing of Advanced Photon Source data on geographically distributed resources are focused on. Two main challenges are considered: (i) modeling of the performance of tomographic reconstruction workflows and (ii) transparent execution of these workflows on distributed resources. For the former, three main stages are considered: (i) data transfer between storage and computational resources, (i) wait/queue time of reconstruction jobs at compute resources, and (iii) computation of reconstruction tasks. These performance models allow evaluation and estimation of the execution time of any given iterative tomographic reconstruction workflow that runs on geographically distributed resources. For the latter challenge, a workflow management system is built, which can automate the execution of workflows and minimize the user interaction with the underlying infrastructure. The system utilizes Globus to perform secure and efficient data transfer operations. The proposed models and the workflow management system are evaluated by using three high-performance computing and two storage resources, all of which are geographically distributed. Workflows were created with different computational requirements using two compute-intensive tomographic reconstruction algorithms. Experimental evaluation shows that the proposed models and system can be used for selecting the optimum resources, which in turn can provide up to 3.13× speedup (on experimented resources). Moreover, the error rates of the models range between 2.1 and 23.3% (considering workflow execution times), where the accuracy of the model estimations increases with higher computational demands in reconstruction tasks. PMID:27359149

Optimization of tomographic reconstruction workflows on geographically distributed resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bicer, Tekin; Gursoy, Doga; Kettimuthu, Rajkumar

New technological advancements in synchrotron light sources enable data acquisitions at unprecedented levels. This emergent trend affects not only the size of the generated data but also the need for larger computational resources. Although beamline scientists and users have access to local computational resources, these are typically limited and can result in extended execution times. Applications that are based on iterative processing as in tomographic reconstruction methods require high-performance compute clusters for timely analysis of data. Here, time-sensitive analysis and processing of Advanced Photon Source data on geographically distributed resources are focused on. Two main challenges are considered: (i) modelingmore » of the performance of tomographic reconstruction workflows and (ii) transparent execution of these workflows on distributed resources. For the former, three main stages are considered: (i) data transfer between storage and computational resources, (i) wait/queue time of reconstruction jobs at compute resources, and (iii) computation of reconstruction tasks. These performance models allow evaluation and estimation of the execution time of any given iterative tomographic reconstruction workflow that runs on geographically distributed resources. For the latter challenge, a workflow management system is built, which can automate the execution of workflows and minimize the user interaction with the underlying infrastructure. The system utilizes Globus to perform secure and efficient data transfer operations. The proposed models and the workflow management system are evaluated by using three high-performance computing and two storage resources, all of which are geographically distributed. Workflows were created with different computational requirements using two compute-intensive tomographic reconstruction algorithms. Experimental evaluation shows that the proposed models and system can be used for selecting the optimum resources, which in turn can provide up to 3.13× speedup (on experimented resources). Furthermore, the error rates of the models range between 2.1 and 23.3% (considering workflow execution times), where the accuracy of the model estimations increases with higher computational demands in reconstruction tasks.« less

Investigating cognitive ability and self-reported driving performance of post-stroke adults in a driving simulator.

PubMed

Blane, Alison; Falkmer, Torbjörn; Lee, Hoe C; Dukic Willstrand, Tania

2018-01-01

Background Safe driving is a complex activity that requires calibration. This means the driver can accurately assess the level of task demand required for task completion and can accurately evaluate their driving capability. There is much debate on the calibration ability of post-stroke drivers. Objectives The aim of this study was to assess the cognition, self-rated performance, and estimation of task demand in a driving simulator with post-stroke drivers and controls. Methods A between-groups study design was employed, which included a post-stroke driver group and a group of similarly aged older control drivers. Both groups were observed driving in two simulator-based driving scenarios and asked to complete the NASA Task Load Index (TLX) to assess their perceived task demand and self-rate their driving performance. Participants also completed a battery of psychometric tasks to assess attention and executive function, which was used to determine whether post-stroke cognitive impairment impacted on calibration. Results There was no difference in the amount of perceived task demand required to complete the driving task. Despite impairments in cognition, the post-stroke drivers were not more likely to over-estimate their driving abilities than controls. On average, the post-stroke drivers self-rated themselves more poorly than the controls and this rating was related to cognitive ability. Conclusion This study suggests that post-stroke drivers may be aware of their deficits and adjust their driving behavior. Furthermore, using self-performance measures alongside a driving simulator and cognitive assessments may provide complementary fitness-to-drive assessments, as well as rehabilitation tools during post-stroke recovery.

CCSSM: Examining the Critical Areas in Grades 5 and 6

ERIC Educational Resources Information Center

Polly, Drew; Orrill, Chandra

2012-01-01

Cognitively demanding tasks are at the heart of the implementation of the Common Core State Standards in Mathematics (CCSSI 2010). As with all the grades, teachers of grades 5 and 6 are challenged to use tasks that simultaneously address the grade-level Standards as well as the Standards for Mathematical Practice (SMP). Cognitively demanding tasks…

Learning to See Teaching in New Ways: A Foundation for Maintaining Cognitive Demand

ERIC Educational Resources Information Center

Tekkumru Kisa, Miray; Stein, Mary Kay

2015-01-01

Students' opportunities to learn how to think are embedded in the instructional tasks with which they are invited to engage in the classroom. Prior research has revealed that the selection and use of cognitively demanding tasks does not guarantee high-level student thinking during their enactment. To address this challenge, we designed and…

Children's Choice Strategies: The Effects of Age and Task Demands

ERIC Educational Resources Information Center

Bereby-Meyer, Yoella; Assor, Avi; Katz, Idit

2004-01-01

Two experiments examined the effect of age and cognitive demands on children's choice strategies. Children aged 8-9 and 12-13 years were asked to choose among either two or four products that differed in several attributes of varying importance to them. Choice tasks were designed to differentiate between the lexicographic and the equal-weighting…

When global rule reversal meets local task switching: The neural mechanisms of coordinated behavioral adaptation to instructed multi-level demand changes.

PubMed

Shi, Yiquan; Wolfensteller, Uta; Schubert, Torsten; Ruge, Hannes

2018-02-01

Cognitive flexibility is essential to cope with changing task demands and often it is necessary to adapt to combined changes in a coordinated manner. The present fMRI study examined how the brain implements such multi-level adaptation processes. Specifically, on a "local," hierarchically lower level, switching between two tasks was required across trials while the rules of each task remained unchanged for blocks of trials. On a "global" level regarding blocks of twelve trials, the task rules could reverse or remain the same. The current task was cued at the start of each trial while the current task rules were instructed before the start of a new block. We found that partly overlapping and partly segregated neural networks play different roles when coping with the combination of global rule reversal and local task switching. The fronto-parietal control network (FPN) supported the encoding of reversed rules at the time of explicit rule instruction. The same regions subsequently supported local task switching processes during actual implementation trials, irrespective of rule reversal condition. By contrast, a cortico-striatal network (CSN) including supplementary motor area and putamen was increasingly engaged across implementation trials and more so for rule reversal than for nonreversal blocks, irrespective of task switching condition. Together, these findings suggest that the brain accomplishes the coordinated adaptation to multi-level demand changes by distributing processing resources either across time (FPN for reversed rule encoding and later for task switching) or across regions (CSN for reversed rule implementation and FPN for concurrent task switching). © 2017 Wiley Periodicals, Inc.

Does a multicomponent exercise program improve dual-task performance in amnestic mild cognitive impairment? A randomized controlled trial.

PubMed

Makizako, Hyuma; Doi, Takehiko; Shimada, Hiroyuki; Yoshida, Daisuke; Tsutsumimoto, Kota; Uemura, Kazuki; Suzuki, Takao

2012-12-01

There has been much interest in exercise interventions as a primary behavioral prevention strategy against cognitive decline. The aim of this study was to evaluate the effect of a multicomponent exercise program on physical and dual-task performances in community-dwelling older adults with amnestic mild cognitive impairment (aMCI). Fifty older adults (23 women) with aMCI (mean age, 76 years) were randomized to an intervention (n=25) or a control group (n=25). The intervention group received a multicomponent exercise program for 90 minutes/day, 2 days/week, or 40 times over six months. The multicomponent exercises included aerobic exercise, muscle strength training and postural balance retraining, which was conducted under multi-task conditions to stimulate attention and memory. Participants in the control group attended two health promotion education classes within six months. Physical and dual-task performances were measured before randomization and after six months. Dual-task performances using reaction times with balance and cognitive demands were measured. The improvement effects on dual-task performances with both balance and cognitive demands were not statistically significant: reaction time with balance demand F1,45=3.3, p=0.07, and cognitive demand F1,45=2.6, p=0.12. However, there was a significant group-by-time interaction on maximal walking speed, which decreased significantly in the control group (F1,45=5.9, p=0.02). This six-month multicomponent exercise program improved maximal walking speed in older adults with aMCI; however, it did not improve dual-task performances assessed by reaction times.

Vagal and sympathetic activity in burnouts during a mentally demanding workday.

PubMed

Zanstra, Ydwine J; Schellekens, Jan M H; Schaap, Cas; Kooistra, Libbe

2006-01-01

We study differences in task performance and related sympathetic-vagal reaction patterns between burnouts and controls during a mentally demanding workday. Thirty-nine adults with burnout and 40 healthy controls performed mental tasks during a simulated workday. At pretest, just before lunch (lunch test) and at the end of the day (posttest), a Stroop color word task was administered as a probe task. Efficiency (the relation between performance and effort during the probe task), performance (reaction time and errors), and effort (self-report) were measured, as well as cardiovascular indices of sympathetic (blood pressure) and vagal (respiratory sinus arrhythmia) activity. Performance and effort investment of both burnouts and controls did not differ during pretest. As the day progressed the performance of controls improved more than the performance of burnouts. Moreover, the control group showed a decrease of blood pressure in response to mental task demands, a decrease in respiratory sinus arrhythmia activity, and no change in experienced effort. In the burnout group, no change could be demonstrated in blood pressure, suggesting a sympathetic predominance in the sympathetic-vagal balance. Burnouts experienced an increase in effort and were more tired at the end of the workday. Burnouts and healthy controls differ in their pattern of sympathetic-vagal activity only after long-lasting work demands. Findings give limited support to Porges's view that in healthy subjects, the vagal system is more responsive to challenging task situations than in chronically stressed individuals. The distinction between two phases in the burnout on the basis of behavioral and physiological characteristics is discussed.

Time constraints in the alcohol purchase task.

PubMed

Kaplan, Brent A; Reed, Derek D; Murphy, James G; Henley, Amy J; Reed, Florence D DiGennaro; Roma, Peter G; Hursh, Steven R

2017-06-01

Hypothetical purchase tasks have advanced behavioral economic evaluations of demand by circumventing practical and ethical restrictions associated with delivering drug reinforcers to participants. Numerous studies examining the reliability and validity of purchase task methodology suggest that it is a valuable method for assessing demand that warrants continued use and evaluation. Within the literature examining purchase tasks, the alcohol purchase task (APT) has received the most investigation, and currently represents the most experimentally validated variant. However, inconsistencies in purchase task methodology between studies exist, even within APT studies, and, to date, none have assessed the influence of experimental economic constraints on responding. This study examined changes in Q0 (reported consumption when drinks are free), breakpoint (price that suppresses consumption), and α (rate of change in demand elasticity) in the presence of different hypothetical durations of access to alcohol in an APT. One hundred seventy-nine participants (94 males, 85 females) from Amazon Mechanical Turk completed 3 APTs that varied in the duration of time at a party (i.e., access to alcoholic beverages) as described in the APT instructions (i.e., vignette). The 3 durations included 5-hr (used by Murphy et al., 2013), 1-hr, and 9-hr time frames. We found that hypothetical duration of access was significantly related to Q0 and breakpoint at the individual level. Additionally, group-level mean α decreased significantly with increases in duration of access, thus indicating relatively higher demand for alcohol with longer durations of access. We discuss implications for conducting hypothetical purchase task research and alcohol misuse prevention efforts. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The effects of task difficulty and workload on training

NASA Technical Reports Server (NTRS)

Mane, Amir; Wickens, Christopher D.

1986-01-01

Four hypotheses regarding the possible effects of workload and task difficulty on training are proposed. These are: (1) increased levels of task difficulty will facilitate learning to the extent that these increases are (a) resource loading and (b) intrinsic to the component task to be learned; (2) decrease of task difficulty will facilitate learning to the extent that these decreases (a) reduce the resource load and (b) are extrinsic of the component task to be learned; (3) the lerner's tendency to conserve resources may bead to the adoption of undesirable, short-term, low resource strategies early in training; and (4) the effect of changes in resource demand on learning will depend upon the similarity of the resource whose demand is changed to the resource involved in learning.

Performance on verbal and low-verbal false belief tasks: evidence from children with Williams syndrome.

PubMed

Van Herwegen, Jo; Dimitriou, Dagmara; Rundblad, Gabriella

2013-01-01

Previous studies that have investigated the relationship between performance on theory of mind (ToM) tasks and verbal abilities in individuals with Williams syndrome (WS) have reported contradictory findings with some showing that language abilities aid performance on ToM tasks while others have found that participants with WS fail these tasks because of their verbal demands. The current study investigated this relationship again comparing performance on a classical change-location task to two newly developed low-verbal tasks, one change-location task and one unexpected content task. Thirty children with WS (aged 5-17;01 years) and 30 typically developing (TD) children (aged between 2;10 years and 9;09 years), who were matched for vocabulary comprehension scores were included in the study. Although performance in the WS group was significantly poorer compared to the TD group on all three tasks, performance was not predicted by their receptive vocabulary or grammatical ability scores. In addition, ToM abilities in both groups depended on the cognitive demands of the task at hand. This finding shows that performance on ToM tasks in WS is not necessarily hindered by their delayed language abilities but rather by the task administered. This could potentially affect the diagnosis of developmental disorders, such as Autism Spectrum Disorders, and comparison of ToM abilities across developmental disorders. Readers of this article should be able to (1) describe the current state of theory of mind research in Williams syndrome, (2) identify which cognitive abilities might explain performance on theory of mind tasks in both typically developing children and in children with Williams syndrome, and (3) interpret the importance of task demands when assessing children's theory of mind abilities. Copyright © 2013 Elsevier Inc. All rights reserved.

Oxygen Level and LFP in Task-Positive and Task-Negative Areas: Bridging BOLD fMRI and Electrophysiology.

PubMed

Bentley, William J; Li, Jingfeng M; Snyder, Abraham Z; Raichle, Marcus E; Snyder, Lawrence H

2016-01-01

The human default mode network (DMN) shows decreased blood oxygen level dependent (BOLD) signals in response to a wide range of attention-demanding tasks. Our understanding of the specifics regarding the neural activity underlying these "task-negative" BOLD responses remains incomplete. We paired oxygen polarography, an electrode-based oxygen measurement technique, with standard electrophysiological recording to assess the relationship of oxygen and neural activity in task-negative posterior cingulate cortex (PCC), a hub of the DMN, and visually responsive task-positive area V3 in the awake macaque. In response to engaging visual stimulation, oxygen, LFP power, and multi-unit activity in PCC showed transient activation followed by sustained suppression. In V3, oxygen, LFP power, and multi-unit activity showed an initial phasic response to the stimulus followed by sustained activation. Oxygen responses were correlated with LFP power in both areas, although the apparent hemodynamic coupling between oxygen level and electrophysiology differed across areas. Our results suggest that oxygen responses reflect changes in LFP power and multi-unit activity and that either the coupling of neural activity to blood flow and metabolism differs between PCC and V3 or computing a linear transformation from a single LFP band to oxygen level does not capture the true physiological process. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Student reflections on learning with challenging tasks: `I think the worksheets were just for practice, and the challenges were for maths'

NASA Astrophysics Data System (ADS)

Russo, James; Hopkins, Sarah

2017-09-01

The current study considered young students' (7 and 8 years old) experiences and perceptions of mathematics lessons involving challenging (i.e. cognitively demanding) tasks. We used the Constant Comparative Method to analyse the interview responses ( n = 73) regarding what work artefacts students were most proud of creating and why. Five themes emerged that characterised student reflections: enjoyment, effort, learning, productivity and meaningful mathematics. Overall, there was evidence that students embraced struggle and persisted when engaged in mathematics lessons involving challenging tasks and, moreover, that many students enjoyed the process of being challenged. In the second section of the paper, the lesson structure preferences of a subset of participants ( n = 23) when learning with challenging tasks are considered. Overall, more students preferred the teach-first lesson structure to the task-first lesson structure, primarily because it activated their cognition to prepare them for work on the challenging task. However, a substantial minority of students (42 %) instead endorsed the task-first lesson structure, with several students explaining they preferred this structure precisely because it was so cognitively demanding. Other reasons for preferring the task-first structure included that it allowed the focus of the lesson to be on the challenging task and the subsequent discussion of student work. A key implication of these combined findings is that, for many students, work on challenging tasks appeared to remain cognitively demanding irrespective of the structure of the lesson.

A reservoir of time constants for memory traces in cortical neurons

PubMed Central

Bernacchia, Alberto; Seo, Hyojung; Lee, Daeyeol; Wang, Xiao-Jing

2011-01-01

According to reinforcement learning theory of decision making, reward expectation is computed by integrating past rewards with a fixed timescale. By contrast, we found that a wide range of time constants is available across cortical neurons recorded from monkeys performing a competitive game task. By recognizing that reward modulates neural activity multiplicatively, we found that one or two time constants of reward memory can be extracted for each neuron in prefrontal, cingulate, and parietal cortex. These timescales ranged from hundreds of milliseconds to tens of seconds, according to a power-law distribution, which is consistent across areas and reproduced by a “reservoir” neural network model. These neuronal memory timescales were weakly but significantly correlated with those of monkey's decisions. Our findings suggest a flexible memory system, where neural subpopulations with distinct sets of long or short memory timescales may be selectively deployed according to the task demands. PMID:21317906

Definition and characterization of an extended multiple-demand network.

PubMed

Camilleri, J A; Müller, V I; Fox, P; Laird, A R; Hoffstaedter, F; Kalenscher, T; Eickhoff, S B

2018-01-15

Neuroimaging evidence suggests that executive functions (EF) depend on brain regions that are not closely tied to specific cognitive demands but rather to a wide range of behaviors. A multiple-demand (MD) system has been proposed, consisting of regions showing conjoint activation across multiple demands. Additionally, a number of studies defining networks specific to certain cognitive tasks suggest that the MD system may be composed of a number of sub-networks each subserving specific roles within the system. We here provide a robust definition of an extended MDN (eMDN) based on task-dependent and task-independent functional connectivity analyses seeded from regions previously shown to be convergently recruited across neuroimaging studies probing working memory, attention and inhibition, i.e., the proposed key components of EF. Additionally, we investigated potential sub-networks within the eMDN based on their connectional and functional similarities. We propose an eMDN network consisting of a core whose integrity should be crucial to performance of most operations that are considered higher cognitive or EF. This then recruits additional areas depending on specific demands. Copyright © 2017 Elsevier Inc. All rights reserved.

Language and Memory Improvements following tDCS of Left Lateral Prefrontal Cortex.

PubMed

Hussey, Erika K; Ward, Nathan; Christianson, Kiel; Kramer, Arthur F

2015-01-01

Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing.

Language and Memory Improvements following tDCS of Left Lateral Prefrontal Cortex

PubMed Central

Hussey, Erika K.; Ward, Nathan; Christianson, Kiel; Kramer, Arthur F.

2015-01-01

Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing. PMID:26528814

Improving Running Times for the Determination of Fractional Snow-Covered Area from Landsat TM/ETM+ via Utilization of the CUDA® Programming Paradigm

NASA Astrophysics Data System (ADS)

McGibbney, L. J.; Rittger, K.; Painter, T. H.; Selkowitz, D.; Mattmann, C. A.; Ramirez, P.

2014-12-01

As part of a JPL-USGS collaboration to expand distribution of essential climate variables (ECV) to include on-demand fractional snow cover we describe our experience and implementation of a shift towards the use of NVIDIA's CUDA® parallel computing platform and programming model. In particular the on-demand aspect of this work involves the improvement (via faster processing and a reduction in overall running times) for determination of fractional snow-covered area (fSCA) from Landsat TM/ETM+. Our observations indicate that processing tasks associated with remote sensing including the Snow Covered Area and Grain Size Model (SCAG) when applied to MODIS or LANDSAT TM/ETM+ are computationally intensive processes. We believe the shift to the CUDA programming paradigm represents a significant improvement in the ability to more quickly assert the outcomes of such activities. We use the TMSCAG model as our subject to highlight this argument. We do this by describing how we can ingest a LANDSAT surface reflectance image (typically provided in HDF format), perform spectral mixture analysis to produce land cover fractions including snow, vegetation and rock/soil whilst greatly reducing running time for such tasks. Within the scope of this work we first document the original workflow used to assert fSCA for Landsat TM and it's primary shortcomings. We then introduce the logic and justification behind the switch to the CUDA paradigm for running single as well as batch jobs on the GPU in order to achieve parallel processing. Finally we share lessons learned from the implementation of myriad of existing algorithms to a single set of code in a single target language as well as benefits this ultimately provides scientists at the USGS.

Real-Time linux dynamic clamp: a fast and flexible way to construct virtual ion channels in living cells.

PubMed

Dorval, A D; Christini, D J; White, J A

2001-10-01

We describe a system for real-time control of biological and other experiments. This device, based around the Real-Time Linux operating system, was tested specifically in the context of dynamic clamping, a demanding real-time task in which a computational system mimics the effects of nonlinear membrane conductances in living cells. The system is fast enough to represent dozens of nonlinear conductances in real time at clock rates well above 10 kHz. Conductances can be represented in deterministic form, or more accurately as discrete collections of stochastically gating ion channels. Tests were performed using a variety of complex models of nonlinear membrane mechanisms in excitable cells, including simulations of spatially extended excitable structures, and multiple interacting cells. Only in extreme cases does the computational load interfere with high-speed "hard" real-time processing (i.e., real-time processing that never falters). Freely available on the worldwide web, this experimental control system combines good performance. immense flexibility, low cost, and reasonable ease of use. It is easily adapted to any task involving real-time control, and excels in particular for applications requiring complex control algorithms that must operate at speeds over 1 kHz.

Test Facilities and Experience on Space Nuclear System Developments at the Kurchatov Institute

NASA Astrophysics Data System (ADS)

Ponomarev-Stepnoi, Nikolai N.; Garin, Vladimir P.; Glushkov, Evgeny S.; Kompaniets, George V.; Kukharkin, Nikolai E.; Madeev, Vicktor G.; Papin, Vladimir K.; Polyakov, Dmitry N.; Stepennov, Boris S.; Tchuniyaev, Yevgeny I.; Tikhonov, Lev Ya.; Uksusov, Yevgeny I.

2004-02-01

The complexity of space fission systems and rigidity of requirement on minimization of weight and dimension characteristics along with the wish to decrease expenditures on their development demand implementation of experimental works which results shall be used in designing, safety substantiation, and licensing procedures. Experimental facilities are intended to solve the following tasks: obtainment of benchmark data for computer code validations, substantiation of design solutions when computational efforts are too expensive, quality control in a production process, and ``iron'' substantiation of criticality safety design solutions for licensing and public relations. The NARCISS and ISKRA critical facilities and unique ORM facility on shielding investigations at the operating OR nuclear research reactor were created in the Kurchatov Institute to solve the mentioned tasks. The range of activities performed at these facilities within the implementation of the previous Russian nuclear power system programs is briefly described in the paper. This experience shall be analyzed in terms of methodological approach to development of future space nuclear systems (this analysis is beyond this paper). Because of the availability of these facilities for experiments, the brief description of their critical assemblies and characteristics is given in this paper.

What Do We Really Know about Cognitive Inhibition? Task Demands and Inhibitory Effects across a Range of Memory and Behavioural Tasks

PubMed Central

Noreen, Saima; MacLeod, Malcolm D.

2015-01-01

Our study explores inhibitory control across a range of widely recognised memory and behavioural tasks. Eighty-seven never-depressed participants completed a series of tasks designed to measure inhibitory control in memory and behaviour. Specifically, a variant of the selective retrieval-practice and the Think/No-Think tasks were employed as measures of memory inhibition. The Stroop-Colour Naming and the Go/No-Go tasks were used as measures of behavioural inhibition. Participants completed all 4 tasks. Task presentation order was counterbalanced across 3 separate testing sessions for each participant. Standard inhibitory forgetting effects emerged on both memory tasks but the extent of forgetting across these tasks was not correlated. Furthermore, there was no relationship between memory inhibition tasks and either of the main behavioural inhibition measures. At a time when cognitive inhibition continues to gain acceptance as an explanatory mechanism, our study raises fundamental questions about what we actually know about inhibition and how it is affected by the processing demands of particular inhibitory tasks. PMID:26270470

What Do We Really Know about Cognitive Inhibition? Task Demands and Inhibitory Effects across a Range of Memory and Behavioural Tasks.

PubMed

Noreen, Saima; MacLeod, Malcolm D

2015-01-01

Our study explores inhibitory control across a range of widely recognised memory and behavioural tasks. Eighty-seven never-depressed participants completed a series of tasks designed to measure inhibitory control in memory and behaviour. Specifically, a variant of the selective retrieval-practice and the Think/No-Think tasks were employed as measures of memory inhibition. The Stroop-Colour Naming and the Go/No-Go tasks were used as measures of behavioural inhibition. Participants completed all 4 tasks. Task presentation order was counterbalanced across 3 separate testing sessions for each participant. Standard inhibitory forgetting effects emerged on both memory tasks but the extent of forgetting across these tasks was not correlated. Furthermore, there was no relationship between memory inhibition tasks and either of the main behavioural inhibition measures. At a time when cognitive inhibition continues to gain acceptance as an explanatory mechanism, our study raises fundamental questions about what we actually know about inhibition and how it is affected by the processing demands of particular inhibitory tasks.

Enhancing effects of nicotine and impairing effects of scopolamine on distinct aspects of performance in computerized attention and working memory tasks in marmoset monkeys.

PubMed

Spinelli, Simona; Ballard, Theresa; Feldon, Joram; Higgins, Guy A; Pryce, Christopher R

2006-08-01

With the CAmbridge Neuropsychological Test Automated Battery (CANTAB), computerized neuropsychological tasks can be presented on a touch-sensitive computer screen, and this system has been used to assess cognitive processes in neuropsychiatric patients, healthy volunteers, and species of non-human primate, primarily the rhesus macaque and common marmoset. Recently, we reported that the common marmoset, a small-bodied primate, can be trained to a high and stable level of performance on the CANTAB five-choice serial reaction time (5-CSRT) task of attention, and a novel task of working memory, the concurrent delayed match-to-position (CDMP) task. Here, in order to increase understanding of the specific cognitive demands of these tasks and the importance of acetylcholine to their performance, the effects of systemic delivery of the muscarinic receptor antagonist scopolamine and the nicotinic receptor agonist nicotine were studied. In the 5-CSRT task, nicotine enhanced performance in terms of increased sustained attention, whilst scopolamine led to increased omissions despite a high level of orientation to the correct stimulus location. In the CDMP task, scopolamine impaired performance at two stages of the task that differ moderately in terms of memory retention load but both of which are likely to require working memory, including interference-coping, abilities. Nicotine tended to enhance performance at the long-delay stage specifically but only against a background of relatively low baseline performance. These data are consistent with a dissociation of the roles of muscarinic and nicotinic cholinergic receptors in the regulation of both sustained attention and working memory in primates.

Work-based physiological assessment of physically-demanding trades: a methodological overview.

PubMed

Taylor, Nigel A S; Groeller, Herb

2003-03-01

Technological advances, modified work practices, altered employment strategies, work-related injuries, and the rise in work-related litigation and compensation claims necessitate ongoing trade analysis research. Such research enables the identification and development of gender- and age-neutral skills, physiological attributes and employment standards required to satisfactorily perform critical trade tasks. This paper overviews a methodological approach which may be adopted when seeking to establish trade-specific physiological competencies for physically-demanding trades (occupations). A general template is presented for conducting a trade analyses within physically-demanding trades, such as those encountered within military or emergency service occupations. Two streams of analysis are recommended: the trade analysis and the task analysis. The former involves a progressive dissection of activities and skills into a series of specific tasks (elements), and results in a broad approximation of the types of trade duties, and the links between trade tasks. The latter, will lead to the determination of how a task is performed within a trade, and the physiological attributes required to satisfactorily perform that task. The approach described within this paper is designed to provide research outcomes which have high content, criterion-related and construct validities.

Rethinking the connection between working memory and language impairment.

PubMed

Archibald, Lisa M D; Harder Griebeling, Katherine

2016-05-01

Working memory deficits have been found for children with specific language impairment (SLI) on tasks imposing increasing short-term memory load with or without additional, consistent (and simple) processing load. To examine the processing function of working memory in children with low language (LL) by employing tasks imposing increasing processing loads with constant storage demands individually adjusted based on each participant's short-term memory capacity. School-age groups with LL (n = 17) and typical language with either average (n = 28) or above-average nonverbal intelligence (n = 15) completed complex working memory-span tasks varying processing load while keeping storage demands constant, varying storage demands while keeping processing load constant, simple storage-span tasks, and measures of language and nonverbal intelligence. Teachers completed questionnaires about cognition and learning. Significantly lower scores were found for the LL than either matched group on storage-based tasks, but no group differences were found on the tasks varying processing load. Teachers' ratings of oral expression and mathematics abilities discriminated those who did or did not complete the most challenging cognitive tasks. The results implicate a deficit in the phonological storage but not in the central executive component of working memory for children with LL. Teacher ratings may reveal personality traits related to perseverance of effort in cognitive research. © 2015 Royal College of Speech and Language Therapists.

Cognitive performance under motor demands - On the influence of task difficulty and postural control.

PubMed

Liebherr, Magnus; Weiland-Breckle, Hanna; Grewe, Tanja; Schumacher, Petra B

2018-04-01

We often walk around when we have to think about something, but suddenly stop when we are confronted with a demanding cognitive task, such as calculating 1540*24. While previous neurophysiological research investigated cognitive and motor performance separately, findings that combine both are rare. To get a deeper understanding of the influence of motor demands as well as the difficulty of a simultaneously performed cognitive task, we investigated 20 healthy individuals. Participants performed two cognitive tasks with different levels of difficulty while sitting or standing on one leg. In addition to behavioral data, we recorded the electroencephalogram from 26Ag/AgCI scalp electrodes. The critical time-windows, predefined by visual inspection, yielded an early (200-300 ms, P2) and a subsequent positivity (350-500 ms, P3). Statistical analysis of the early time window registered a motor × cognition interaction. Resolution of this interaction revealed an effect of the cognitive task in the one-legged stance motor condition, with a more pronounced positivity for the difficult task. No significant differences between cognitive tasks emerged for the simple motor condition. The time-window between 350 and 500 ms registered main effects of the motor task and a trend for the cognitive task. While the influence of cognitive task difficulty (in the P3) is in accordance with previous studies, the motor task effect is specific to one-legged stance (cf. no effects for running in previous research). The motor-cognition interaction found in the P2 indicates that the more difficult motor task (one-legged stance) facilitates cognitive task performance. Copyright © 2018 Elsevier B.V. All rights reserved.

Reconfiguration of Brain Network Architectures between Resting-State and Complexity-Dependent Cognitive Reasoning.

PubMed

Hearne, Luke J; Cocchi, Luca; Zalesky, Andrew; Mattingley, Jason B

2017-08-30

Our capacity for higher cognitive reasoning has a measurable limit. This limit is thought to arise from the brain's capacity to flexibly reconfigure interactions between spatially distributed networks. Recent work, however, has suggested that reconfigurations of task-related networks are modest when compared with intrinsic "resting-state" network architecture. Here we combined resting-state and task-driven functional magnetic resonance imaging to examine how flexible, task-specific reconfigurations associated with increasing reasoning demands are integrated within a stable intrinsic brain topology. Human participants (21 males and 28 females) underwent an initial resting-state scan, followed by a cognitive reasoning task involving different levels of complexity, followed by a second resting-state scan. The reasoning task required participants to deduce the identity of a missing element in a 4 × 4 matrix, and item difficulty was scaled parametrically as determined by relational complexity theory. Analyses revealed that external task engagement was characterized by a significant change in functional brain modules. Specifically, resting-state and null-task demand conditions were associated with more segregated brain-network topology, whereas increases in reasoning complexity resulted in merging of resting-state modules. Further increments in task complexity did not change the established modular architecture, but affected selective patterns of connectivity between frontoparietal, subcortical, cingulo-opercular, and default-mode networks. Larger increases in network efficiency within the newly established task modules were associated with higher reasoning accuracy. Our results shed light on the network architectures that underlie external task engagement, and highlight selective changes in brain connectivity supporting increases in task complexity. SIGNIFICANCE STATEMENT Humans have clear limits in their ability to solve complex reasoning problems. It is thought that such limitations arise from flexible, moment-to-moment reconfigurations of functional brain networks. It is less clear how such task-driven adaptive changes in connectivity relate to stable, intrinsic networks of the brain and behavioral performance. We found that increased reasoning demands rely on selective patterns of connectivity within cortical networks that emerged in addition to a more general, task-induced modular architecture. This task-driven architecture reverted to a more segregated resting-state architecture both immediately before and after the task. These findings reveal how flexibility in human brain networks is integral to achieving successful reasoning performance across different levels of cognitive demand. Copyright © 2017 the authors 0270-6474/17/378399-13$15.00/0.

Effects of concurrent physical and cognitive demands on muscle activity and heart rate variability in a repetitive upper-extremity precision task.

PubMed

Srinivasan, Divya; Mathiassen, Svend Erik; Hallman, David M; Samani, Afshin; Madeleine, Pascal; Lyskov, Eugene

2016-01-01

Most previous studies of concurrent physical and cognitive demands have addressed tasks of limited relevance to occupational work, and with dissociated physical and cognitive task components. This study investigated effects on muscle activity and heart rate variability of executing a repetitive occupational task with an added cognitive demand integral to correct task performance. Thirty-five healthy females performed 7.5 min of standardized repetitive pipetting work in a baseline condition and a concurrent cognitive condition involving a complex instruction for correct performance. Average levels and variabilities of electromyographic activities in the upper trapezius and extensor carpi radialis (ECR) muscles were compared between these two conditions. Heart rate and heart rate variability were also assessed to measure autonomic nervous system activation. Subjects also rated perceived fatigue in the neck-shoulder region, as well as exertion. Concurrent cognitive demands increased trapezius muscle activity from 8.2% of maximum voluntary exertion (MVE) in baseline to 9.0% MVE (p = 0.0005), but did not significantly affect ECR muscle activity, heart rate, heart rate variability, perceived fatigue or exertion. Trapezius muscle activity increased by about 10%, without any accompanying cardiovascular response to indicate increased sympathetic activation. We suggest this slight increase in trapezius muscle activity to be due to changed muscle activation patterns within or among shoulder muscles. The results suggest that it may be possible to introduce modest cognitive demands necessary for correct performance in repetitive precision work without any major physiological effects, at least in the short term.

Task demands determine the specificity of the search template.

PubMed

Bravo, Mary J; Farid, Hany

2012-01-01

When searching for an object, an observer holds a representation of the target in mind while scanning the scene. If the observer repeats the search, performance may become more efficient as the observer hones this target representation, or "search template," to match the specific demands of the search task. An effective search template must have two characteristics: It must reliably discriminate the target from the distractors, and it must tolerate variability in the appearance of the target. The present experiment examined how the tolerance of the search template is affected by the search task. Two groups of 18 observers trained on the same set of stimuli blocked either by target image (block-by-image group) or by target category (block-by-category group). One or two days after training, both groups were tested on a related search task. The pattern of test results revealed that the two groups of observers had developed different search templates, and that the templates of the block-by-category observers better captured the general characteristics of the category. These results demonstrate that observers match their search templates to the demands of the search task.

Alterations in cervical muscle activity in functional and stressful tasks in female office workers with neck pain.

PubMed

Johnston, V; Jull, G; Darnell, R; Jimmieson, N L; Souvlis, T

2008-06-01

This study determined differences between computer workers with varying levels of neck pain in terms of work stressors, employee strain, electromyography (EMG) amplitude and heart rate response to various tasks. Participants included 85 workers (33, no pain; 38, mild pain; 14, moderate pain) and 22 non-working controls. Work stressors evaluated were job demands, decision authority, and social support. Heart rate was recorded during three tasks: copy-typing, typing with superimposed stress and a colour word task. Measures included electromyography signals from the sternocleidomastoid (SCM), anterior scalene (AS), cervical extensor (CE) and upper trapezius (UT) muscles bilaterally. Results showed no difference between groups in work stressors or employee strain measures. Workers with and without pain had higher measured levels of EMG amplitude in SCM, AS and CE muscles during the tasks than controls (all P < 0.02). In workers with neck pain, the UT had difficulty in switching off on completion of tasks compared with controls and workers without pain. There was an increase in heart rate, perceived tension and pain and decrease in accuracy for all groups during the stressful tasks with symptomatic workers producing more typing errors than controls and workers without pain. These findings suggest an altered muscle recruitment pattern in the neck flexor and extensor muscles. Whether this is a consequence or source of the musculoskeletal disorder cannot be determined from this study. It is possible that workers currently without symptoms may be at risk of developing a musculoskeletal disorder.

To Switch or Not to Switch: Role of Cognitive Control in Working Memory Training in Older Adults.

PubMed

Basak, Chandramallika; O'Connell, Margaret A

2016-01-01

It is currently not known what are the best working memory training strategies to offset the age-related declines in fluid cognitive abilities. In this randomized clinical double-blind trial, older adults were randomly assigned to one of two types of working memory training - one group was trained on a predictable memory updating task (PT) and another group was trained on a novel, unpredictable memory updating task (UT). Unpredictable memory updating, compared to predictable, requires greater demands on cognitive control (Basak and Verhaeghen, 2011a). Therefore, the current study allowed us to evaluate the role of cognitive control in working memory training. All participants were assessed on a set of near and far transfer tasks at three different testing sessions - before training, immediately after the training, and 1.5 months after completing the training. Additionally, individual learning rates for a comparison working memory task (performed by both groups) and the trained task were computed. Training on unpredictable memory updating, compared to predictable, significantly enhanced performance on a measure of episodic memory, immediately after the training. Moreover, individuals with faster learning rates showed greater gains in this episodic memory task and another new working memory task; this effect was specific to UT. We propose that the unpredictable memory updating training, compared to predictable memory updating training, may a better strategy to improve selective cognitive abilities in older adults, and future studies could further investigate the role of cognitive control in working memory training.

Reduced interhemispheric interaction in non-autistic individuals with normal but high levels of autism traits.

PubMed

O'Keefe, Natalie; Lindell, Annukka K

2013-11-01

People with autism spectrum disorder (ASD) show superior performance for tasks requiring detail-focused processing. Atypical neural connectivity and reduced interhemispheric communication are posited to underlie this cognitive advantage. Given recent conceptualization of autism as a continuum, we sought to investigate whether people with normal but high levels of autism like traits (AQ) also exhibit reduced hemispheric interaction. Sixty right-handed participants completed the AQ questionnaire (Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001) and a lateralised letter matching task that assessed unilateral and bilateral performance in response to simple (physical) and complex (identity) matches. Whereas people with low self-rated AQ scores showed a bilateral advantage for the more complex task, indicating normal interhemispheric interaction, people in the high AQ group failed to show a bilateral gain for the computationally demanding stimuli. This finding of disrupted interhemispheric interaction converges with a dimensional conceptualisation of ASD, suggesting that the structural anomalies of ASD extend to non-autistic individuals with high levels of autism traits. Copyright © 2013 Elsevier Inc. All rights reserved.

The Effects of Presentation Modality, Task Demand, and Content Structure on Age-Related Memory Differences for Prose.

ERIC Educational Resources Information Center

Corgiat, Mark D.; And Others

1989-01-01

Evaluated contributions of age, presentation modality, task demand, and content structure to prose recall variation among adults. Tested 60 young and 60 older adults for recall of ideas in 641-word prose passage. Found recall for total number of idea units was significantly lower for older participants and for auditory presentation across both age…

Subjective evaluation of physical and mental workload interactions across different muscle groups.

PubMed

Mehta, Ranjana K; Agnew, Michael J

2015-01-01

Both physical and mental demands, and their interactions, have been shown to increase biomechanical loading and physiological reactivity as well as impair task performance. Because these interactions have shown to be muscle-dependent, the aim of this study was to determine the sensitivity of the NASA Task Load Index (NASA TLX) and Ratings of Perceived Exertion (RPE) to evaluate physical and mental workload during muscle-specific tasks. Twenty-four participants performed upper extremity and low back exertions at three physical workload levels in the absence and presence of a mental stressor. Outcome measures included RPE and NASA TLX (six sub-scales) ratings. The findings indicate that while both RPEs and NASA TLX ratings were sensitive to muscle-specific changes in physical demand, only an additional mental stressor and its interaction with either physical demand or muscle groups influenced the effort sub-scale and overall workload scores of the NASA TLX. While additional investigations in actual work settings are warranted, the NASA TLX shows promise in evaluating perceived workload that is sensitive not only to physical and mental demands but also sensitive in determining workload for tasks that employ different muscle groups.

Verbal short-term memory shows a specific association with receptive but not productive vocabulary measures in Down syndrome.

PubMed

Majerus, S; Barisnikov, K

2018-01-01

Verbal short-term memory (STM) capacity has been considered to support vocabulary learning in typical children and adults, but evidence for this link is inconsistent for studies in individuals with Down syndrome (DS). The aim of this study was explore the role of processing demands on the association between verbal STM and vocabulary measures in DS, by comparing receptive vocabulary measures with high STM processing demands to productive vocabulary measures with low STM processing demands. Forty-seven adults with Down syndrome were administered receptive vocabulary and productive vocabulary tasks, as well as measures of verbal STM abilities and intellectual efficiency. Bayesian regression analyses showed that verbal STM abilities were strongly and specifically associated with receptive vocabulary measures but not productive lexical abilities after controlling for intellectual efficiency, and this is despite the fact that vocabulary abilities as measured by receptive and productive vocabulary tasks were closely associated. In Down syndrome, verbal STM abilities may be predictive of specific task demands associated with receptive vocabulary tasks rather than of vocabulary development per se. © 2017 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

A quantification of the physiological demands of the army emergency responder in the Australian army.

PubMed

Tofari, Paul J; Laing Treloar, Alison K; Silk, Aaron J

2013-05-01

The Australian Defence Force is reviewing the physical demands of all employment categories in the Australian Army to establish valid and legally defensible assessments. The current assessments, performed in physical training attire, are not specific to job demands. Moreover, the fitness standards decrease based on age and are lower for females, and as job requirements are constant, these assessments are counterintuitive. With regard to the Army Emergency Responder employment category, tasks of physical demand in the present study were selected through consultation with subject-matter experts. Participants consisted of 10 qualified Army Emergency Responder soldiers and three noncareer firefighters under instruction. Real-life firefighting scenarios were witnessed by researchers and helped form task simulations allowing measurement of heart rate and oxygen consumption. Peak oxygen consumption ranged from 21.8 ± 3.8 to 40.0 ± 3.4 mL kg(-1) min(-1) during cutting activities and a search and rescue task, respectively, representing values similar to or higher than the current entry standards. Manual handling tasks were also assessed, with the heaviest measured being two soldiers lifting a 37.7-kg Utility Trunk to 150 cm. The findings provide a quantitative assessment of the physiological demands of Army Emergency Responders, and highlight the need for change in current fitness assessments. Reprint & Copyright © 2013 Association of Military Surgeons of the U.S.

Domain-general contributions to social reasoning: theory of mind and deontic reasoning re-explored.

PubMed

McKinnon, Margaret C; Moscovitch, Morris

2007-02-01

Using older adults and dual-task interference, we examined performance on two social reasoning tasks: theory of mind (ToM) tasks and versions of the deontic selection task involving social contracts and hazardous conditions. In line with performance accounts of social reasoning, evidence from both aging and the dual-task method suggested that domain-general resources contribute to performance of these tasks. Specifically, older adults were impaired relative to younger adults on all types of social reasoning tasks tested; performance varied as a function of the demands these tasks placed on domain-general resources. Moreover, in younger adults, simultaneous performance of a working memory task interfered with younger adults' performance on both types of social reasoning tasks; here too, the magnitude of the interference effect varied with the processing demands of each task. Limits placed on social reasoning by executive functions contribute a great deal to performance, even in old age and in healthy younger adults under conditions of divided attention. The role of potentially non-modular and modular contributions to social reasoning is discussed.

False-belief understanding in 2.5-year-olds: Evidence from two novel verbal spontaneous-response tasks

PubMed Central

Scott, Rose M.; He, Zijing; Baillargeon, Renée; Cummins, Denise

2011-01-01

Recent research indicates that toddlers and infants succeed at various non-verbal spontaneous-response false-belief tasks; here we asked whether toddlers would also succeed at verbal spontaneous-response false-belief tasks that imposed significant linguistic demands. 2.5-year-olds were tested using two novel tasks: a preferential-looking task in which children listened to a false-belief story while looking at a picture book (with matching and non-matching pictures), and a violation-of-expectation task in which children watched an adult “Subject” answer (correctly or incorrectly) a standard false-belief question. Positive results were obtained with both tasks, despite their linguistic demands. These results (1) support the distinction between spontaneous-and elicited-response tasks by showing that toddlers succeed at verbal false-belief tasks that do not require them to answer direct questions about agents’ false beliefs, (2) reinforce claims of robust continuity in early false-belief understanding as assessed by spontaneous-response tasks, and (3) provide researchers with new experimental tasks for exploring early false-belief understanding in neurotypical and autistic populations. PMID:22356174

False-belief understanding in 2.5-year-olds: evidence from two novel verbal spontaneous-response tasks.

PubMed

Scott, Rose M; He, Zijing; Baillargeon, Renée; Cummins, Denise

2012-03-01

Recent research indicates that toddlers and infants succeed at various non-verbal spontaneous-response false-belief tasks; here we asked whether toddlers would also succeed at verbal spontaneous-response false-belief tasks that imposed significant linguistic demands. We tested 2.5-year-olds using two novel tasks: a preferential-looking task in which children listened to a false-belief story while looking at a picture book (with matching and non-matching pictures), and a violation-of-expectation task in which children watched an adult 'Subject' answer (correctly or incorrectly) a standard false-belief question. Positive results were obtained with both tasks, despite their linguistic demands. These results (1) support the distinction between spontaneous- and elicited-response tasks by showing that toddlers succeed at verbal false-belief tasks that do not require them to answer direct questions about agents' false beliefs, (2) reinforce claims of robust continuity in early false-belief understanding as assessed by spontaneous-response tasks, and (3) provide researchers with new experimental tasks for exploring early false-belief understanding in neurotypical and autistic populations. © 2011 Blackwell Publishing Ltd.

An evaluation of nursing tasks.

PubMed

Baptiste, Andrea

2011-01-01

Functional capacity evaluations have been criticized as being too general in theory and not being accurate enough to determine what tasks an employee can perform. This paper will describe results of a descriptive study that was conducted in a laboratory setting to objectively determine the physical demands of patient transfer tasks performed by nurses. Fifty three tasks were analyzed and broken down into sub-tasks to quantify the peak force required to perform each sub-task in order to determine which tasks pose healthcare workers at highest risk of injury. Dissecting the transfer task into segments allows us to see which part of the task requires high forces on the part of the caregiver. The task can then be modified to eliminate the risk of injury to the caregiver. This modification can be accomplished by using healthcare technology, such as floor based or overhead lifts, friction reducing devices, sit to stand lifts, properly designed slings, and motorized beds/trolleys. Technological solutions are available for some of these high risk tasks and should be implemented where applicable to reduce the force demand and eliminate or reduce the risk of injury to healthcare workers in nursing.

Prospective memory: effects of divided attention on spontaneous retrieval.

PubMed

Harrison, Tyler L; Mullet, Hillary G; Whiffen, Katie N; Ousterhout, Hunter; Einstein, Gilles O

2014-02-01

We examined the effects of divided attention on the spontaneous retrieval of a prospective memory intention. Participants performed an ongoing lexical decision task with an embedded prospective memory demand, and also performed a divided-attention task during some segments of lexical decision trials. In all experiments, monitoring was highly discouraged, and we observed no evidence that participants engaged monitoring processes. In Experiment 1, performing a moderately demanding divided-attention task (a digit detection task) did not affect prospective memory performance. In Experiment 2, performing a more challenging divided-attention task (random number generation) impaired prospective memory. Experiment 3 showed that this impairment was eliminated when the prospective memory cue was perceptually salient. Taken together, the results indicate that spontaneous retrieval is not automatic and that challenging divided-attention tasks interfere with spontaneous retrieval and not with the execution of a retrieved intention.

Go Deeper, Go Deeper: Understanding submarine command and control during the completion of dived tracking operations.

PubMed

Roberts, Aaron P J; Stanton, Neville A; Fay, Daniel T

2018-05-01

This is a world's first-of-a-kind study providing empirical evidence for understanding submarine control room performance when completing higher and lower demand Dived Tracking (DT) scenarios. A submarine control room simulator was built, using a non-commercial version of Dangerous Waters as the simulation engine. The creation of networked workstations allowed a team of nine operators to perform tasks completed by submarine command teams during DT. The Event Analysis of Systemic Teamwork (EAST) method was used to model the social, task and information networks and describe command team performance. Ten teams were recruited for the study, affording statistical comparisons of how command team roles and level of demand affected performance. Results indicate that command teams can covertly DT a contact differently depending on demand (e.g. volume of contacts). In low demand it was possible to use periscope more often than in high demand, in a 'duck-and-run' fashion. Therefore, the type of information and frequency of particular task completion, was significantly different between the higher and lower demand conditions. This resulted in different operators in the command team experiencing greater demand depending on how the DT mission objective was completed. Potential bottlenecks in the command team were identified and implications are discussed alongside suggestions for future work. Copyright © 2018 Elsevier Ltd. All rights reserved.

GAMUT: GPU accelerated microRNA analysis to uncover target genes through CUDA-miRanda

PubMed Central

2014-01-01

Background Non-coding sequences such as microRNAs have important roles in disease processes. Computational microRNA target identification (CMTI) is becoming increasingly important since traditional experimental methods for target identification pose many difficulties. These methods are time-consuming, costly, and often need guidance from computational methods to narrow down candidate genes anyway. However, most CMTI methods are computationally demanding, since they need to handle not only several million query microRNA and reference RNA pairs, but also several million nucleotide comparisons within each given pair. Thus, the need to perform microRNA identification at such large scale has increased the demand for parallel computing. Methods Although most CMTI programs (e.g., the miRanda algorithm) are based on a modified Smith-Waterman (SW) algorithm, the existing parallel SW implementations (e.g., CUDASW++ 2.0/3.0, SWIPE) are unable to meet this demand in CMTI tasks. We present CUDA-miRanda, a fast microRNA target identification algorithm that takes advantage of massively parallel computing on Graphics Processing Units (GPU) using NVIDIA's Compute Unified Device Architecture (CUDA). CUDA-miRanda specifically focuses on the local alignment of short (i.e., ≤ 32 nucleotides) sequences against longer reference sequences (e.g., 20K nucleotides). Moreover, the proposed algorithm is able to report multiple alignments (up to 191 top scores) and the corresponding traceback sequences for any given (query sequence, reference sequence) pair. Results Speeds over 5.36 Giga Cell Updates Per Second (GCUPs) are achieved on a server with 4 NVIDIA Tesla M2090 GPUs. Compared to the original miRanda algorithm, which is evaluated on an Intel Xeon E5620@2.4 GHz CPU, the experimental results show up to 166 times performance gains in terms of execution time. In addition, we have verified that the exact same targets were predicted in both CUDA-miRanda and the original miRanda implementations through multiple test datasets. Conclusions We offer a GPU-based alternative to high performance compute (HPC) that can be developed locally at a relatively small cost. The community of GPU developers in the biomedical research community, particularly for genome analysis, is still growing. With increasing shared resources, this community will be able to advance CMTI in a very significant manner. Our source code is available at https://sourceforge.net/projects/cudamiranda/. PMID:25077821

Minimum toe clearance events in divided attention treadmill walking in older and young adults: a cross-sectional study.

PubMed

Santhiranayagam, Braveena K; Lai, Daniel T H; Sparrow, W A; Begg, Rezaul K

2015-07-12

Falls in older adults during walking frequently occur while performing a concurrent task; that is, dividing attention to respond to other demands in the environment. A particularly hazardous fall-related event is tripping due to toe-ground contact during the swing phase of the gait cycle. The aim of this experiment was to determine the effects of divided attention on tripping risk by investigating the gait cycle event Minimum Toe Clearance (MTC). Fifteen older adults (mean 73.1 years) and 15 young controls (mean 26.1 years) performed three walking tasks on motorized treadmill: (i) at preferred walking speed (preferred walking), (ii) while carrying a glass of water at a comfortable walking speed (dual task walking), and (iii) speed-matched control walking without the glass of water (control walking). Position-time coordinates of the toe were acquired using a 3 dimensional motion capture system (Optotrak NDI, Canada). When MTC was present, toe height at MTC (MTC_Height) and MTC timing (MTC_Time) were calculated. The proportion of non-MTC gait cycles was computed and for non-MTC gait cycles, toe-height was extracted at the mean MTC_Time. Both groups maintained mean MTC_Height across all three conditions. Despite greater MTC_Height SD in preferred gait, the older group reduced their variability to match the young group in dual task walking. Compared to preferred speed walking, both groups attained MTC earlier in dual task and control conditions. The older group's MTC_Time SD was greater across all conditions; in dual task walking, however, they approximated the young group's SD. Non-MTC gait cycles were more frequent in the older group across walking conditions (for example, in preferred walking: young - 2.9 %; older - 18.7 %). In response to increased attention demands older adults preserve MTC_Height but exercise greater control of the critical MTC event by reducing variability in both MTC_Height and MTC_Time. A further adaptive locomotor control strategy to reduce the likelihood of toe-ground contacts is to attain higher mid-swing clearance by eliminating the MTC event, i.e. demonstrating non-MTC gaits cycles.

Visual ergonomics and computer work--is it all about computer glasses?

PubMed

Jonsson, Christina

2012-01-01

The Swedish Provisions on Work with Display Screen Equipment and the EU Directive on the minimum safety and health requirements for work with display screen equipment cover several important visual ergonomics aspects. But a review of cases and questions to the Swedish Work Environment Authority clearly shows that most attention is given to the demands for eyesight tests and special computer glasses. Other important visual ergonomics factors are at risk of being neglected. Today computers are used everywhere, both at work and at home. Computers can be laptops, PDA's, tablet computers, smart phones, etc. The demands on eyesight tests and computer glasses still apply but the visual demands and the visual ergonomics conditions are quite different compared to the use of a stationary computer. Based on this review, we raise the question if the demand on the employer to provide the employees with computer glasses is outdated.

Not All Lexical Access Tasks Are Created Equal: Lexical Development between Three and Five

ERIC Educational Resources Information Center

Isacoff, Nora M.; Stromswold, Karin

2014-01-01

Lexical access tasks are designed to measure efficiency of lexical access, but task demands and methods vary greatly. Many lexical access tasks do not account for confounding factors including competence in other linguistic abilities. In this study, preschoolers were given two lexical access tasks. In the single-category naming (SCN) task,…

System on a chip with MPEG-4 capability

NASA Astrophysics Data System (ADS)

Yassa, Fathy; Schonfeld, Dan

2002-12-01

Current products supporting video communication applications rely on existing computer architectures. RISC processors have been used successfully in numerous applications over several decades. DSP processors have become ubiquitous in signal processing and communication applications. Real-time applications such as speech processing in cellular telephony rely extensively on the computational power of these processors. Video processors designed to implement the computationally intensive codec operations have also been used to address the high demands of video communication applications (e.g., cable set-top boxes and DVDs). This paper presents an overview of a system-on-chip (SOC) architecture used for real-time video in wireless communication applications. The SOC specifications answer to the system requirements imposed by the application environment. A CAM-based video processor is used to accelerate data intensive video compression tasks such as motion estimations and filtering. Other components are dedicated to system level data processing and audio processing. A rich set of I/Os allows the SOC to communicate with other system components such as baseband and memory subsystems.

Dependency Distance Differences across Interpreting Types: Implications for Cognitive Demand

PubMed Central

Liang, Junying; Fang, Yuanyuan; Lv, Qianxi; Liu, Haitao

2017-01-01

Interpreting is generally recognized as a particularly demanding language processing task for the cognitive system. Dependency distance, the linear distance between two syntactically related words in a sentence, is an index of sentence complexity and is also able to reflect the cognitive constraints during various tasks. In the current research, we examine the difference in dependency distance among three interpreting types, namely, simultaneous interpreting, consecutive interpreting and read-out translated speech based on a treebank comprising these types of interpreting output texts with dependency annotation. Results show that different interpreting renditions yield different dependency distances, and consecutive interpreting texts entail the smallest dependency distance other than those of simultaneous interpreting and read-out translated speech, suggesting that consecutive interpreting bears heavier cognitive demands than simultaneous interpreting. The current research suggests for the first time that interpreting is an extremely demanding cognitive task that can further mediate the dependency distance of output sentences. Such findings may be due to the minimization of dependency distance under cognitive constraints. PMID:29312027

Do job demands and job control affect problem-solving?

PubMed

Bergman, Peter N; Ahlberg, Gunnel; Johansson, Gun; Stoetzer, Ulrich; Aborg, Carl; Hallsten, Lennart; Lundberg, Ingvar

2012-01-01

The Job Demand Control model presents combinations of working conditions that may facilitate learning, the active learning hypothesis, or have detrimental effects on health, the strain hypothesis. To test the active learning hypothesis, this study analysed the effects of job demands and job control on general problem-solving strategies. A population-based sample of 4,636 individuals (55% women, 45% men) with the same job characteristics measured at two times with a three year time lag was used. Main effects of demands, skill discretion, task authority and control, and the combined effects of demands and control were analysed in logistic regressions, on four outcomes representing general problem-solving strategies. Those reporting high on skill discretion, task authority and control, as well as those reporting high demand/high control and low demand/high control job characteristics were more likely to state using problem solving strategies. Results suggest that working conditions including high levels of control may affect how individuals cope with problems and that workplace characteristics may affect behaviour in the non-work domain.

Skill acquisition while operating in-vehicle information systems: interface design determines the level of safety-relevant distractions.

PubMed

Jahn, Georg; Krems, Josef F; Gelau, Christhard

2009-04-01

This study tested whether the ease of learning to use human-machine interfaces of in-vehicle information systems (IVIS) can be assessed at standstill. Assessing the attentional demand of IVIS should include an evaluation of ease of learning, because the use of IVIS at low skill levels may create safety-relevant distractions. Skill acquisition in operating IVIS was quantified by fitting the power law of practice to training data sets collected in a driving study and at standstill. Participants practiced manual destination entry with two route guidance systems differing in cognitive demand. In Experiment 1, a sample of middle-aged participants was trained while steering routes of varying driving demands. In Experiment 2, another sample of middle-aged participants was trained at standstill. In Experiment 1, display glance times were less affected by driving demands than by total task times and decreased at slightly higher speed-up rates (0.02 higher on average) than task times collected at standstill in Experiment 2. The system interface that minimized cognitive demand was operated more quickly and was easier to learn. Its system delays increased static task times, which still predicted 58% of variance in display glance times compared with even 76% for the second system. The ease of learning to use an IVIS interface and the decrease in attentional demand with training can be assessed at standstill. Fitting the power law of practice to static task times yields parameters that predict display glance times while driving, which makes it possible to compare interfaces with regard to ease of learning.

Individual and combined effects of cannabis and tobacco on drug reward processing in non-dependent users.

PubMed

Hindocha, Chandni; Lawn, Will; Freeman, Tom P; Curran, H Valerie

2017-11-01

Cannabis and tobacco are often smoked simultaneously in joints, and this practice may increase the risks of developing tobacco and/or cannabis use disorders. Currently, there is no human experimental research on how these drugs interact on addiction-related measures. This study aimed to investigate how cannabis and tobacco, each alone and combined together in joints, affected individuals' demand for cannabis puffs and cigarettes, explicit liking of drug and non-drug-related stimuli and craving. A double-blind, 2 (active cannabis, placebo cannabis) × 2 (active tobacco, placebo tobacco) crossover design was used with 24 non-dependent cannabis and tobacco smokers. They completed a pleasantness rating task (PRT), a marijuana purchase task (MPT) and a cigarette purchase task (CPT) alongside measures of craving pre- and post-drug administration. Relative to placebo cannabis, active cannabis reduced liking of cannabis-associated stimuli and increased response time to all stimuli except cigarette-related stimuli. Relative to placebo cannabis, active cannabis decreased demand for cannabis puffs (trends for breakpoint and elasticity) and cigarettes (breakpoint, P max , O max ) on several characteristics of the purchase tasks. We found no evidence that active tobacco, both alone or combined with cannabis, had an effect on liking, demand or craving. Acutely, cannabis reduced liking of cannabis-related stimuli and demand for cannabis itself. Acute cannabis also reduced demand for cigarettes on the CPT. Acute tobacco administration did not affect demand or pleasantness ratings for cigarettes themselves or cannabis. In non-dependent cannabis and tobacco co-users, tobacco did not influence the rewarding effects of cannabis.

Task difficulty modulates brain-behavior correlations in language production and cognitive control: Behavioral and fMRI evidence from a phonological go/no-go picture-naming paradigm.

PubMed

Zhang, Haoyun; Eppes, Anna; Beatty-Martínez, Anne; Navarro-Torres, Christian; Diaz, Michele T

2018-06-19

Language production and cognitive control are complex processes that involve distinct yet interacting brain networks. However, the extent to which these processes interact and their neural bases have not been thoroughly examined. Here, we investigated the neural and behavioral bases of language production and cognitive control via a phonological go/no-go picture-naming task. Naming difficulty and cognitive control demands (i.e., conflict monitoring and response inhibition) were manipulated by varying the proportion of naming trials (go trials) and inhibition trials (no-go trials) across task runs. The results demonstrated that as task demands increased, participants' behavioral performance declined (i.e., longer reaction times on naming trials, more commission errors on inhibition trials) whereas brain activation generally increased. Increased activation was found not only within the language network but also in domain-general control regions. Additionally, right superior and inferior frontal and left supramarginal gyri were sensitive to increased task difficulty during both language production and response inhibition. We also found both positive and negative brain-behavior correlations. Most notably, increased activation in sensorimotor regions, such as precentral and postcentral gyri, was associated with better behavioral performance, in both successful picture naming and successful inhibition. Moreover, comparing the strength of correlations across conditions indicated that the brain-behavior correlations in sensorimotor regions that were associated with improved performance became stronger as task demands increased. Overall, our results suggest that cognitive control demands affect language production, and that successfully coping with increases in task difficulty relies on both language-specific and domain-general cognitive control regions.

The Attentional Demand of Automobile Driving Revisited: Occlusion Distance as a Function of Task-Relevant Event Density in Realistic Driving Scenarios.

PubMed

Kujala, Tuomo; Mäkelä, Jakke; Kotilainen, Ilkka; Tokkonen, Timo

2016-02-01

We studied the utility of occlusion distance as a function of task-relevant event density in realistic traffic scenarios with self-controlled speed. The visual occlusion technique is an established method for assessing visual demands of driving. However, occlusion time is not a highly informative measure of environmental task-relevant event density in self-paced driving scenarios because it partials out the effects of changes in driving speed. Self-determined occlusion times and distances of 97 drivers with varying backgrounds were analyzed in driving scenarios simulating real Finnish suburban and highway traffic environments with self-determined vehicle speed. Occlusion distances varied systematically with the expected environmental demands of the manipulated driving scenarios whereas the distributions of occlusion times remained more static across the scenarios. Systematic individual differences in the preferred occlusion distances were observed. More experienced drivers achieved better lane-keeping accuracy than inexperienced drivers with similar occlusion distances; however, driving experience was unexpectedly not a major factor for the preferred occlusion distances. Occlusion distance seems to be an informative measure for assessing task-relevant event density in realistic traffic scenarios with self-controlled speed. Occlusion time measures the visual demand of driving as the task-relevant event rate in time intervals, whereas occlusion distance measures the experienced task-relevant event density in distance intervals. The findings can be utilized in context-aware distraction mitigation systems, human-automated vehicle interaction, road speed prediction and design, as well as in the testing of visual in-vehicle tasks for inappropriate in-vehicle glancing behaviors in any dynamic traffic scenario for which appropriate individual occlusion distances can be defined. © 2015, Human Factors and Ergonomics Society.

Context-specific adjustment of cognitive control: Transfer of adaptive control sets.

PubMed

Surrey, Caroline; Dreisbach, Gesine; Fischer, Rico

2017-11-01

Cognitive control protects processing of relevant information from interference by irrelevant information. The level of this processing selectivity can be flexibly adjusted to different control demands (e.g., frequency of conflict) associated with a certain context, leading to the formation of specific context-control associations. In the present study we investigated the robustness and transferability of the acquired context-control demands to new situations. In three experiments, we used a version of the context-specific proportion congruence (CSPC) paradigm, in which each context (e.g., location) is associated with a specific conflict frequency, determining high and low control demands. In a learning phase, associations between context and control demands were established. In a subsequent transfer block, stimulus-response mappings, whole task sets, or context-control demands changed. Results showed an impressive robustness of context-control associations, as context-specific adjustments of control from the learning phase were virtually unaffected by new stimuli and tasks in the transfer block. Only a change of the context-control demand eliminated the context-specific adjustment of control. These findings suggest that context-control associations that have proven to be adaptive in the past are continuously applied despite major changes in the task structure as long as the context-control associations remain the same.

EEG alpha synchronization is related to top-down processing in convergent and divergent thinking

PubMed Central

Benedek, Mathias; Bergner, Sabine; Könen, Tanja; Fink, Andreas; Neubauer, Aljoscha C.

2011-01-01

Synchronization of EEG alpha activity has been referred to as being indicative of cortical idling, but according to more recent evidence it has also been associated with active internal processing and creative thinking. The main objective of this study was to investigate to what extent EEG alpha synchronization is related to internal processing demands and to specific cognitive process involved in creative thinking. To this end, EEG was measured during a convergent and a divergent thinking task (i.e., creativity-related task) which once were processed involving low and once involving high internal processing demands. High internal processing demands were established by masking the stimulus (after encoding) and thus preventing further bottom-up processing. Frontal alpha synchronization was observed during convergent and divergent thinking only under exclusive top-down control (high internal processing demands), but not when bottom-up processing was allowed (low internal processing demands). We conclude that frontal alpha synchronization is related to top-down control rather than to specific creativity-related cognitive processes. Frontal alpha synchronization, which has been observed in a variety of different creativity tasks, thus may not reflect a brain state that is specific for creative cognition but can probably be attributed to high internal processing demands which are typically involved in creative thinking. PMID:21925520

A portable fNIRS system with eight channels

NASA Astrophysics Data System (ADS)

Si, Juanning; Zhao, Ruirui; Zhang, Yujin; Zuo, Nianming; Zhang, Xin; Jiang, Tianzi

2015-03-01

Abundant study on the hemodynamic response of a brain have brought quite a few advances in technologies of measuring it. The most benefitted is the functional near infrared spectroscope (fNIRS). A variety of devices have been developed for different applications. Because portable fNIRS systems were more competent to measure responses either of special subjects or in natural environment, several kinds of portable fNIRS systems have been reported. However, they all required a computer for receiving data. The extra computer increases the cost of a fNIRS system. What's more noticeable is the space required to locate the computer even for a portable system. It will discount the portability of the fNIRS system. So we designed a self-contained eight channel fNIRS system, which does not demand a computer to receive data and display data in a monitor. Instead, the system is centered by an ARM core CPU, which takes charge in organizing data and saving data, and then displays data on a touch screen. The system has also been validated by experiments on phantoms and on subjects in tasks.

Stress and decision making: neural correlates of the interaction between stress, executive functions, and decision making under risk.

PubMed

Gathmann, Bettina; Schulte, Frank P; Maderwald, Stefan; Pawlikowski, Mirko; Starcke, Katrin; Schäfer, Lena C; Schöler, Tobias; Wolf, Oliver T; Brand, Matthias

2014-03-01

Stress and additional load on the executive system, produced by a parallel working memory task, impair decision making under risk. However, the combination of stress and a parallel task seems to preserve the decision-making performance [e.g., operationalized by the Game of Dice Task (GDT)] from decreasing, probably by a switch from serial to parallel processing. The question remains how the brain manages such demanding decision-making situations. The current study used a 7-tesla magnetic resonance imaging (MRI) system in order to investigate the underlying neural correlates of the interaction between stress (induced by the Trier Social Stress Test), risky decision making (GDT), and a parallel executive task (2-back task) to get a better understanding of those behavioral findings. The results show that on a behavioral level, stressed participants did not show significant differences in task performance. Interestingly, when comparing the stress group (SG) with the control group, the SG showed a greater increase in neural activation in the anterior prefrontal cortex when performing the 2-back task simultaneously with the GDT than when performing each task alone. This brain area is associated with parallel processing. Thus, the results may suggest that in stressful dual-tasking situations, where a decision has to be made when in parallel working memory is demanded, a stronger activation of a brain area associated with parallel processing takes place. The findings are in line with the idea that stress seems to trigger a switch from serial to parallel processing in demanding dual-tasking situations.

Water demand forecasting: review of soft computing methods.

PubMed

Ghalehkhondabi, Iman; Ardjmand, Ehsan; Young, William A; Weckman, Gary R

2017-07-01

Demand forecasting plays a vital role in resource management for governments and private companies. Considering the scarcity of water and its inherent constraints, demand management and forecasting in this domain are critically important. Several soft computing techniques have been developed over the last few decades for water demand forecasting. This study focuses on soft computing methods of water consumption forecasting published between 2005 and 2015. These methods include artificial neural networks (ANNs), fuzzy and neuro-fuzzy models, support vector machines, metaheuristics, and system dynamics. Furthermore, it was discussed that while in short-term forecasting, ANNs have been superior in many cases, but it is still very difficult to pick a single method as the overall best. According to the literature, various methods and their hybrids are applied to water demand forecasting. However, it seems soft computing has a lot more to contribute to water demand forecasting. These contribution areas include, but are not limited, to various ANN architectures, unsupervised methods, deep learning, various metaheuristics, and ensemble methods. Moreover, it is found that soft computing methods are mainly used for short-term demand forecasting.

Shared and distinct contributions of rostrolateral prefrontal cortex to analogical reasoning and episodic memory retrieval.

PubMed

Westphal, Andrew J; Reggente, Nicco; Ito, Kaori L; Rissman, Jesse

2016-03-01

Rostrolateral prefrontal cortex (RLPFC) is widely appreciated to support higher cognitive functions, including analogical reasoning and episodic memory retrieval. However, these tasks have typically been studied in isolation, and thus it is unclear whether they involve common or distinct RLPFC mechanisms. Here, we introduce a novel functional magnetic resonance imaging (fMRI) task paradigm to compare brain activity during reasoning and memory tasks while holding bottom-up perceptual stimulation and response demands constant. Univariate analyses on fMRI data from twenty participants identified a large swath of left lateral prefrontal cortex, including RLPFC, that showed common engagement on reasoning trials with valid analogies and memory trials with accurately retrieved source details. Despite broadly overlapping recruitment, multi-voxel activity patterns within left RLPFC reliably differentiated these two trial types, highlighting the presence of at least partially distinct information processing modes. Functional connectivity analyses demonstrated that while left RLPFC showed consistent coupling with the fronto-parietal control network across tasks, its coupling with other cortical areas varied in a task-dependent manner. During the memory task, this region strengthened its connectivity with the default mode and memory retrieval networks, whereas during the reasoning task it coupled more strongly with a nearby left prefrontal region (BA 45) associated with semantic processing, as well as with a superior parietal region associated with visuospatial processing. Taken together, these data suggest a domain-general role for left RLPFC in monitoring and/or integrating task-relevant knowledge representations and showcase how its function cannot solely be attributed to episodic memory or analogical reasoning computations. © 2015 Wiley Periodicals, Inc.

Flexible explicit but rigid implicit learning in a visuomotor adaptation task

PubMed Central

Bond, Krista M.

2015-01-01

There is mounting evidence for the idea that performance in a visuomotor rotation task can be supported by both implicit and explicit forms of learning. The implicit component of learning has been well characterized in previous experiments and is thought to arise from the adaptation of an internal model driven by sensorimotor prediction errors. However, the role of explicit learning is less clear, and previous investigations aimed at characterizing the explicit component have relied on indirect measures such as dual-task manipulations, posttests, and descriptive computational models. To address this problem, we developed a new method for directly assaying explicit learning by having participants verbally report their intended aiming direction on each trial. While our previous research employing this method has demonstrated the possibility of measuring explicit learning over the course of training, it was only tested over a limited scope of manipulations common to visuomotor rotation tasks. In the present study, we sought to better characterize explicit and implicit learning over a wider range of task conditions. We tested how explicit and implicit learning change as a function of the specific visual landmarks used to probe explicit learning, the number of training targets, and the size of the rotation. We found that explicit learning was remarkably flexible, responding appropriately to task demands. In contrast, implicit learning was strikingly rigid, with each task condition producing a similar degree of implicit learning. These results suggest that explicit learning is a fundamental component of motor learning and has been overlooked or conflated in previous visuomotor tasks. PMID:25855690

Sex differences on a computerized mental rotation task disappear with computer familiarization.

PubMed

Roberts, J E; Bell, M A

2000-12-01

The area of cognitive research that has produced the most consistent sex differences is spatial ability. Particularly, men consistently perform better on mental rotation tasks than do women. This study examined the effects of familiarization with a computer on performance of a computerized two-dimensional mental rotation task. Two groups of college students (N=44) performed the rotation task, with one group performing a color-matching task that allowed them to be familiarized with the computer prior to the rotation task. Among the participants who only performed the rotation task, the 11 men performed better than the 11 women. Among the participants who performed the computer familiarization task before the rotation task, how ever, there were no sex differences on the mental rotation task between the 10 men and 12 women. These data indicate that sex differences on this two-dimensional task may reflect familiarization with the computer, not the mental rotation component of the task. Further research with larger samples and increased range of task difficulty is encouraged.

Development of a SaaS application probe to the physical properties of the Earth's interior: An attempt at moving HPC to the cloud

NASA Astrophysics Data System (ADS)

Huang, Qian

2014-09-01

Scientific computing often requires the availability of a massive number of computers for performing large-scale simulations, and computing in mineral physics is no exception. In order to investigate physical properties of minerals at extreme conditions in computational mineral physics, parallel computing technology is used to speed up the performance by utilizing multiple computer resources to process a computational task simultaneously thereby greatly reducing computation time. Traditionally, parallel computing has been addressed by using High Performance Computing (HPC) solutions and installed facilities such as clusters and super computers. Today, it has been seen that there is a tremendous growth in cloud computing. Infrastructure as a Service (IaaS), the on-demand and pay-as-you-go model, creates a flexible and cost-effective mean to access computing resources. In this paper, a feasibility report of HPC on a cloud infrastructure is presented. It is found that current cloud services in IaaS layer still need to improve performance to be useful to research projects. On the other hand, Software as a Service (SaaS), another type of cloud computing, is introduced into an HPC system for computing in mineral physics, and an application of which is developed. In this paper, an overall description of this SaaS application is presented. This contribution can promote cloud application development in computational mineral physics, and cross-disciplinary studies.

Learning to Predict Demand in a Transport-Resource Sharing Task

DTIC Science & Technology

2015-09-01

exhaustive manner. We experimented with the scikit- learn machine- learning library for Python and a range of R packages before settling on R. We...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited LEARNING TO...COVERED Master’s thesis 4. TITLE AND SUBTITLE LEARNING TO PREDICT DEMAND IN A TRANSPORT-RESOURCE SHARING TASK 5. FUNDING NUMBERS 6. AUTHOR

The active learning hypothesis of the job-demand-control model: an experimental examination.

PubMed

Häusser, Jan Alexander; Schulz-Hardt, Stefan; Mojzisch, Andreas

2014-01-01

The active learning hypothesis of the job-demand-control model [Karasek, R. A. 1979. "Job Demands, Job Decision Latitude, and Mental Strain: Implications for Job Redesign." Administration Science Quarterly 24: 285-307] proposes positive effects of high job demands and high job control on performance. We conducted a 2 (demands: high vs. low) × 2 (control: high vs. low) experimental office workplace simulation to examine this hypothesis. Since performance during a work simulation is confounded by the boundaries of the demands and control manipulations (e.g. time limits), we used a post-test, in which participants continued working at their task, but without any manipulation of demands and control. This post-test allowed for examining active learning (transfer) effects in an unconfounded fashion. Our results revealed that high demands had a positive effect on quantitative performance, without affecting task accuracy. In contrast, high control resulted in a speed-accuracy tradeoff, that is participants in the high control conditions worked slower but with greater accuracy than participants in the low control conditions.

Effects of two hospital bed design features on physical demands and usability during brake engagement and patient transportation: a repeated measures experimental study.

PubMed

Kim, Sunwook; Barker, Linsey M; Jia, Bochen; Agnew, Michael J; Nussbaum, Maury A

2009-03-01

Work-related musculoskeletal disorders (WMSDs) are prevalent among healthcare workers worldwide. While existing research has focused on patient-handling techniques during activities which require direct patient contact (e.g., patient transfer), nursing tasks also involve other patient-handling activities, such as engaging bed brakes and transporting patients in beds, which could render healthcare workers at risk of developing WMSDs. Effectiveness of hospital bed design features (brake pedal location and steering-assistance) was evaluated in terms of physical demands and usability during brake engagement and patient transportation tasks. Two laboratory-based studies were conducted. In simulated brake engagement tasks, three brake pedal locations (head-end vs. foot-end vs. side of a bed) and two hands conditions (hands-free vs. hands-occupied) were manipulated. Additionally, both in-room and corridor patient transportation tasks were simulated, in which activation of steering-assistance features (5th wheel and/or front wheel caster lock) and two patient masses were manipulated. Nine novice participants were recruited from the local student population and community for each study. During brake engagement, trunk flexion angle, task completion time, and questionnaires were used to quantify postural comfort and usability. For patient transportation, dependent measures were hand forces and questionnaire responses. Brake pedal locations and steering-assistance features in hospital beds had significant effects on physical demands and usability during brake engagement and patient transportation tasks. Specifically, a brake pedal at the head-end of a bed increased trunk flexion by 74-224% and completion time by 53-74%, compared to other pedal locations. Participants reported greater overall perceived difficulty and less postural comfort with the brake pedal at the head-end. During in-room transportation, participants generally reported "Neither Low nor High" physical demands with the 5th wheel activated, compared to "Moderately High" physical demands when the 5th wheel was deactivated. Corridor transportation was similarly reported to be easier when a steering-assistance feature (the 5th wheel or front caster lock) was activated. Braking and steering-assistance features of hospital beds can have important effects on task efficiency and physical demands placed on healthcare workers. Selection of specific designs may thus be able to improve productivity and contribute to a reduction in WMSDs risk among healthcare workers.

Getting to the Root of Fine Motor Skill Performance in Dentistry: Brain Activity During Dental Tasks in a Virtual Reality Haptic Simulation.

PubMed

Perry, Suzanne; Bridges, Susan M; Zhu, Frank; Leung, W Keung; Burrow, Michael F; Poolton, Jamie; Masters, Rich Sw

2017-12-12

There is little evidence considering the relationship between movement-specific reinvestment (a dimension of personality which refers to the propensity for individuals to consciously monitor and control their movements) and working memory during motor skill performance. Functional near-infrared spectroscopy (fNIRS) measuring oxyhemoglobin demands in the frontal cortex during performance of virtual reality (VR) psychomotor tasks can be used to examine this research gap. The aim of this study was to determine the potential relationship between the propensity to reinvest and blood flow to the dorsolateral prefrontal cortices of the brain. A secondary aim was to determine the propensity to reinvest and performance during 2 dental tasks carried out using haptic VR simulators. We used fNIRS to assess oxygen demands in 24 undergraduate dental students during 2 dental tasks (clinical, nonclinical) on a VR haptic simulator. We used the Movement-Specific Reinvestment Scale questionnaire to assess the students' propensity to reinvest. Students with a high propensity for movement-specific reinvestment displayed significantly greater oxyhemoglobin demands in an area associated with working memory during the nonclinical task (Spearman correlation, r s =.49, P=.03). This small-scale study suggests that neurophysiological differences are evident between high and low reinvesters during a dental VR task in terms of oxyhemoglobin demands in an area associated with working memory. ©Suzanne Perry, Susan M Bridges, Frank Zhu, W Keung Leung, Michael F Burrow, Jamie Poolton, Rich SW Masters. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 12.12.2017.

The role of production and teamwork practices in construction safety: a cognitive model and an empirical case study.

PubMed

Mitropoulos, Panagiotis Takis; Cupido, Gerardo

2009-01-01

In construction, the challenge for researchers and practitioners is to develop work systems (production processes and teams) that can achieve high productivity and high safety at the same time. However, construction accident causation models ignore the role of work practices and teamwork. This study investigates the mechanisms by which production and teamwork practices affect the likelihood of accidents. The paper synthesizes a new model for construction safety based on the cognitive perspective (Fuller's Task-Demand-Capability Interface model, 2005) and then presents an exploratory case study. The case study investigates and compares the work practices of two residential framing crews: a 'High Reliability Crew' (HRC)--that is, a crew with exceptional productivity and safety over several years, and an average performing crew from the same company. The model explains how the production and teamwork practices generate the work situations that workers face (the task demands) and affect the workers ability to cope (capabilities). The case study indicates that the work practices of the HRC directly influence the task demands and match them with the applied capabilities. These practices were guided by the 'principle' of avoiding errors and rework and included work planning and preparation, work distribution, managing the production pressures, and quality and behavior monitoring. The Task Demand-Capability model links construction research to a cognitive model of accident causation and provides a new way to conceptualize safety as an emergent property of the production practices and teamwork processes. The empirical evidence indicates that the crews' work practices and team processes strongly affect the task demands, the applied capabilities, and the match between demands and capabilities. The proposed model and the exploratory case study will guide further discovery of work practices and teamwork processes that can increase both productivity and safety in construction operations. Such understanding will enable training of construction foremen and crews in these practices to systematically develop high reliability crews.

An information theory account of late frontoparietal ERP positivities in cognitive control.

PubMed

Barceló, Francisco; Cooper, Patrick S

2018-03-01

ERP research on task switching has revealed distinct transient and sustained positive waveforms (latency circa 300-900 ms) while shifting task rules or stimulus-response (S-R) mappings. However, it remains unclear whether such switch-related positivities show similar scalp topography and index context-updating mechanisms akin to those posed for domain-general (i.e., classic P300) positivities in many task domains. To examine this question, ERPs were recorded from 31 young adults (18-30 years) while they were intermittently cued to switch or repeat their perceptual categorization of Gabor gratings varying in color and thickness (switch task), or else they performed two visually identical control tasks (go/no-go and oddball). Our task cueing paradigm examined two temporarily distinct stages of proactive rule updating and reactive rule execution. A simple information theory model helped us gauge cognitive demands under distinct temporal and task contexts in terms of low-level S-R pathways and higher-order rule updating operations. Task demands modulated domain-general (indexed by classic oddball P3) and switch positivities-indexed by both a cue-locked late positive complex and a sustained positivity ensuing task transitions. Topographic scalp analyses confirmed subtle yet significant split-second changes in the configuration of neural sources for both domain-general P3s and switch positivities as a function of both the temporal and task context. These findings partly meet predictions from information estimates, and are compatible with a family of P3-like potentials indexing functionally distinct neural operations within a common frontoparietal "multiple demand" system during the preparation and execution of simple task rules. © 2016 Society for Psychophysiological Research.

Free recall and outdoor running: cognitive and physical demand interference.

PubMed

Epling, Samantha L; Blakely, Megan J; Russell, Paul N; Helton, William S

2016-10-01

Cognitive resource theory is a proposed explanation for people's limited ability to perform multiple tasks simultaneously. Reallocation of a restricted supply of cognitive resources to two or more tasks may be detrimental to performance on one or both tasks. Many professionals in high-risk fields, such as those engaged in firefighting, military, and search and rescue missions, face simultaneous mental and physical demands, yet little is known about the resources required to move over the natural terrain these operators may encounter. In the present research, we investigated whether interference was found between outdoor running and a word recall task. As hypothesized, a reduction in word recall was observed in the dual task compared to a recall-alone task; however, the distance run was not significantly different between the dual task and the run-alone task. Subjective reports of workload, task focus, and being "spent" (measures calculated from responses on a questionnaire) were greatest in the dual task. These results support the cognitive resource theory and have important theoretical and practical implications. Further research is required to better understand the type and extent of cognitive resources required by such physical tasks and the potential interference with simultaneous mental tasks.

Team structure and regulatory focus: the impact of regulatory fit on team dynamic.

PubMed

Dimotakis, Nikolaos; Davison, Robert B; Hollenbeck, John R

2012-03-01

We report a within-teams experiment testing the effects of fit between team structure and regulatory task demands on task performance and satisfaction through average team member positive affect and helping behaviors. We used a completely crossed repeated-observations design in which 21 teams enacted 2 tasks with different regulatory focus characteristics (prevention and promotion) in 2 organizational structures (functional and divisional), resulting in 84 observations. Results suggested that salient regulatory demands inherent in the task interacted with structure to determine objective and subjective team-level outcomes, such that functional structures were best suited to (i.e., had best fit with) tasks with a prevention regulatory focus and divisional structures were best suited to tasks with a promotion regulatory focus. This contingency finding integrates regulatory focus and structural contingency theories, and extends them to the team level with implications for models of performance, satisfaction, and team dynamics.

Information Management For Tactical Reconnaissance

NASA Astrophysics Data System (ADS)

White, James P.

1984-12-01

The expected battlefield tactics of the 1980's and 1990's will be fluid and dynamic. If tactical reconnaissance is to meet this challenge, it must explore all ways of accelerating the flow of information through the reconnaissance cycle, from the moment a tasking request is received to the time the mission results are delivered to the requestor. In addition to near real-time dissemination of reconnaissance information, the mission planning phase needs to be more responsive to the rapidly changing battlefield scenario. By introducing Artificial Intelligence (AI) via an expert system to the mission planning phase, repetitive and computational tasks can be more readily performed by the ground-based mission planning system, thereby permitting the aircrew to devote more of their time to target study. Transporting the flight plan, plus other mission data, to the aircraft is simple with the Fairchild Data Transfer Equipment (DTE). Aircrews are relieved of the tedious, error-prone, and time-consuming task of manually keying-in avionics initialization data. Post-flight retrieval of mission data via the DTE will permit follow-on aircrews, just starting their mission planning phase, to capitalize on current threat data collected by the returning aircrew. Maintenance data retrieved from the recently flown mission will speed-up the aircraft turn-around by providing near-real time fault detection/isolation. As future avionics systems demand more information, a need for a computer-controlled, smart data base or expert system on-board the aircraft will emerge.

Work Functioning Among Firefighters: A Comparison Between Self-Reported Limitations and Functional Task Performance.

PubMed

MacDermid, Joy C; Tang, Kenneth; Sinden, Kathryn E; D'Amico, Robert

2018-05-25

Purpose Performance-based and disease indicators have been widely studied in firefighters; self-reported work role limitations have not. The aim of this study was to describe the distributions and correlations of a generic self-reported Work Limitations Questionnaire (WLQ-26) and firefighting-specific task performance-based tests. Methods Active firefighters from the City of Hamilton Fire Services (n = 293) were recruited. Participants completed the WLQ-26 to quantify on-the-job difficulties over five work domains: work scheduling (4 items), output demands (7 items), physical demands (8 items), mental demands (4 items), and social demands (3 items). A subset of participants (n = 149) were also assessed on hose drag and stair climb with a high-rise pack performance-based tests. Descriptive statistics and correlations were used to compare item/subscale performance; and to describe the inter-relationships between tests. Results The mean WLQ-26 item scores (/5) ranged from 4.1 to 4.4 (median = 5 for all items); most firefighters (54.5-80.5%) selected "difficult none of the time" response option on all items. A substantial ceiling effect was observed across all five WLQ-26 subscales as 44.0-55.6% were in the highest category. Subscale means ranged from 61.8 (social demands) to 78.7 (output demands and physical demands). Internal consistency exceeded 0.90 on all subscales. For the hose drag task, the mean time-to-completion was 48.0 s (SD = 14.5; range 20.4-95.0). For the stair climb task, the mean time-to-completion was 76.7 s (SD = 37.2; range 21.0-218.0). There were no significant correlations between self-report work limitations and performance of firefighting tasks. Conclusions The WLQ-26 measured five domains, but had ceiling effects in firefighters. Performance-based testing showed wider score range, lacked ceiling effects and did not correlate to the WLQ-26. A firefighter-specific, self-report role functioning scale may be needed to identify compromised work role capabilities in firefighters.

Errorless learning of prospective memory tasks: An experimental investigation in people with memory disorders

PubMed Central

Fish, Jessica E.; Manly, Tom; Kopelman, Michael D.; Morris, Robin G.

2015-01-01

The term prospective memory (PM) refers to memory for future intentions. PM problems are frequent in people with cognitive impairment and, because they are central to the realisation of many everyday goals, are important in rehabilitation. Event-based PM tasks (EBPM) are environmentally-cued and have primarily mnemonic demands, whereas time-based PM tasks (TBPM) require self-initiated retrieval, and have greater executive demands. Errorless learning (EL) is an encoding method that results in superior retrospective memory compared with “errorful” learning (EF). As this EL advantage (ELA) likely stems from its reduced explicit memory demands, and there is no such advantage for executive tasks, a greater ELA for EBPM than TBPM was predicted. Fourteen adults with neurological memory impairment completed PM tasks under four counterbalanced conditions: EL of EBPM, EL of TBPM, EF of EBPM, and EF of TBPM. A significant ELA was observed for EBPM (d = .63), but not TBPM (d = –.01). These results extend the evidence for EL within cognitive rehabilitation, by showing for the first time that the method can benefit future action in addition to retrospective memory. The clinical implications are also clear: errorless learning techniques may be usefully employed to support completion of day-to-day EBPM tasks. PMID:24894460

A steady state visually evoked potential investigation of memory and ageing.

PubMed

Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

2009-04-01

Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and latency associated with memory performance. Participants were 15 older (59-67 years) and 14 younger (20-30 years) adults who performed an object working memory (OWM) task and a contextual recognition memory (CRM) task, whilst the SSVEP was recorded from 64 electrode sites. Retention of a single object in the low demand OWM task was characterised by smaller frontal SSVEP amplitude and latency differences in older adults than in younger adults, indicative of an age-associated reduction in neural processes. Recognition of visual images in the more difficult CRM task was accompanied by larger, more sustained SSVEP amplitude and latency decreases over temporal parietal regions in older adults. In contrast, the more transient, frontally mediated pattern of activity demonstrated by younger adults suggests that younger and older adults utilize different neural resources to perform recognition judgements. The results provide support for compensatory processes in the aging brain; at lower task demands, older adults demonstrate reduced neural activity, whereas at greater task demands neural activity is increased.

Task-dependent modulation of regions in the left temporal cortex during auditory sentence comprehension.

PubMed

Zhang, Linjun; Yue, Qiuhai; Zhang, Yang; Shu, Hua; Li, Ping

2015-01-01

Numerous studies have revealed the essential role of the left lateral temporal cortex in auditory sentence comprehension along with evidence of the functional specialization of the anterior and posterior temporal sub-areas. However, it is unclear whether task demands (e.g., active vs. passive listening) modulate the functional specificity of these sub-areas. In the present functional magnetic resonance imaging (fMRI) study, we addressed this issue by applying both independent component analysis (ICA) and general linear model (GLM) methods. Consistent with previous studies, intelligible sentences elicited greater activity in the left lateral temporal cortex relative to unintelligible sentences. Moreover, responses to intelligibility in the sub-regions were differentially modulated by task demands. While the overall activation patterns of the anterior and posterior superior temporal sulcus and middle temporal gyrus (STS/MTG) were equivalent during both passive and active tasks, a middle portion of the STS/MTG was found to be selectively activated only during the active task under a refined analysis of sub-regional contributions. Our results not only confirm the critical role of the left lateral temporal cortex in auditory sentence comprehension but further demonstrate that task demands modulate functional specialization of the anterior-middle-posterior temporal sub-areas. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Asteroids@Home

NASA Astrophysics Data System (ADS)

Durech, Josef; Hanus, J.; Vanco, R.

2012-10-01

We present a new project called Asteroids@home (http://asteroidsathome.net/boinc). It is a volunteer-computing project that uses an open-source BOINC (Berkeley Open Infrastructure for Network Computing) software to distribute tasks to volunteers, who provide their computing resources. The project was created at the Astronomical Institute, Charles University in Prague, in cooperation with the Czech National Team. The scientific aim of the project is to solve a time-consuming inverse problem of shape reconstruction of asteroids from sparse-in-time photometry. The time-demanding nature of the problem comes from the fact that with sparse-in-time photometry the rotation period of an asteroid is not apriori known and a huge parameter space must be densely scanned for the best solution. The nature of the problem makes it an ideal task to be solved by distributed computing - the period parameter space can be divided into small bins that can be scanned separately and then joined together to give the globally best solution. In the framework of the the project, we process asteroid photometric data from surveys together with asteroid lightcurves and we derive asteroid shapes and spin states. The algorithm is based on the lightcurve inversion method developed by Kaasalainen et al. (Icarus 153, 37, 2001). The enormous potential of distributed computing will enable us to effectively process also the data from future surveys (Large Synoptic Survey Telescope, Gaia mission, etc.). We also plan to process data of a synthetic asteroid population to reveal biases of the method. In our presentation, we will describe the project, show the first results (new models of asteroids), and discuss the possibilities of its further development. This work has been supported by the grant GACR P209/10/0537 of the Czech Science Foundation and by the Research Program MSM0021620860 of the Ministry of Education of the Czech Republic.

Upper Extremity Muscle Activity During In-Phase and Anti-Phase Continuous Pushing Tasks.

PubMed

Gruevski, Kristina M; Hodder, Joanne N; Keir, Peter J

2017-11-01

To determine the effect of anti-phase, in-phase bimanual and unimanual simulated industrial pushing tasks and frequency on upper extremity muscle activity. Research investigating symmetrical (in-phase) and asymmetrical (anti-phase) pushing exertions is limited despite a high prevalence in industry. Fifteen female participants completed five pushing tasks using a dual handle apparatus at three frequencies: 15 cycles per minute (cpm), 30 cpm, and self-selected. Tasks included two bimanual symmetrical pushes (constrained and unconstrained), two bimanual asymmetrical pushes (reciprocating and continuous), and one right unimanual push. Surface electromyography (EMG) from the right anterior, middle, and posterior deltoid (AD, MD, and PD); right and left trapezius (RT and LT); right pectoralis major (PM); and right and left external obliques (REO and LEO) was collected and normalized to maximum voluntary effort. There was a task by frequency interaction in the AD, MD, PD, and RT ( p < .005), where activity in AD, MD, and PD was highest in the continuous task at 15 cpm, but activity was similar across task in 30 cpm and self-selected. Muscle activity coefficient of variation was lowest during continuous task across all frequencies. Continuous, anti-phase pushes and constrained, in-phase pushes had the highest muscle activity demands and the least amount of variability in muscle activity and therefore may present the greatest risk of injury. Anti-phase pushing is known to have a greater cognitive demand, and this study demonstrated that it also has a greater physical demand when performed continuously.

Manipulating perceptual parameters in a continuous performance task.

PubMed

Shalev, Nir; Humphreys, Glyn; Demeyere, Nele

2018-02-01

Sustained attention (SA) is among the most studied faculties of human cognition, and thought to be crucial for many aspects of behavior. Measuring SA often relies on performance on a continuous, low-demanding task. Such continuous performance tasks (CPTs) have many variations, and sustained attention is typically estimated based on variability in reaction times. While relying on reaction times may be useful in some cases, it can pose a challenge when working with clinical populations. To increase interpersonal variability in task parameters that do not rely on speed, researchers have increased demands for memory and response inhibition. These approaches, however, may be confounded when used to assess populations that suffer from multiple cognitive deficits. In the current study, we propose a new approach for increasing task variability by increasing the attentional demands. In order to do so, we created a new variation of a CPT - a masked version, where inattention is more likely to cause misidentifying a target. After establishing that masking indeed decreases target detection, we further investigated which task parameter may influence response biases. To do so, we contrasted two versions of the CPT with different target/distractor ratio. We then established how perceptual parameters can be controlled independently in a CPT. Following the experimental manipulations, we tested the MCCPT with aging controls and chronic stroke patients to assure the task can be used with target populations. The results confirm the MCCPT as a task providing high sensitivity without relying on reaction speed, and feasible for patients.

Reversibility and measurement in quantum computing

NASA Astrophysics Data System (ADS)

Leãao, J. P.

1998-03-01

The relation between computation and measurement at a fundamental physical level is yet to be understood. Rolf Landauer was perhaps the first to stress the strong analogy between these two concepts. His early queries have regained pertinence with the recent efforts to developed realizable models of quantum computers. In this context the irreversibility of quantum measurement appears in conflict with the requirement of reversibility of the overall computation associated with the unitary dynamics of quantum evolution. The latter in turn is responsible for the features of superposition and entanglement which make some quantum algorithms superior to classical ones for the same task in speed and resource demand. In this article we advocate an approach to this question which relies on a model of computation designed to enforce the analogy between the two concepts instead of demarcating them as it has been the case so far. The model is introduced as a symmetrization of the classical Turing machine model and is then carried on to quantum mechanics, first as a an abstract local interaction scheme (symbolic measurement) and finally in a nonlocal noninteractive implementation based on Aharonov-Bohm potentials and modular variables. It is suggested that this implementation leads to the most ubiquitous of quantum algorithms: the Discrete Fourier Transform.

Learning to think like a user: using cognitive task analysis to meet today's health care design challenges.

PubMed

Militello, L G

1998-01-01

The growing role of information technology in our society has changed the very nature of many of the tasks that workers are called on to perform. Technology has resulted in a dramatic reduction in the number of proceduralized, rote tasks that workers must face. The impact of technology on many tasks and functions has been to greatly increase demands on the cognitive skills of workers. More procedural or predictable tasks are now handled by smart machines, while workers are responsible for tasks that require inference, diagnosis, judgment, and decision making. The increase in the cognitive demands placed on workers and the redistribution of tasks have created a need for a better understanding of the cognitive components of many tasks. This need has been recognized by many in the health care domain, including the U.S. Food and Drug Administration (FDA). Recent FDA regulations encourage the use of human factors in the development of medical devices, instruments, and systems. One promising set of methods for filling this need is cognitive task analysis.

Severe tinnitus and its effect on selective and divided attention.

PubMed

Stevens, Catherine; Walker, Gary; Boyer, Morten; Gallagher, Melinda

2007-05-01

The effect of chronic, severe tinnitus on two visual tasks was investigated. A general depletion of resources hypothesis states that overall performance would be impaired in a tinnitus group relative to a control group whereas a controlled processing hypothesis states that only tasks that are demanding, requiring strategic processes, are affected. Eleven participants who had experienced severe tinnitus for more than two years comprised the tinnitus group. A control group was matched for age and verbal IQ. Levels of anxiety, depression, and high frequency average hearing level were treated as covariates. Tasks consisted of the say-word (easy) and say-color (demanding) conditions of the Stroop task, a single (baseline) reaction time (RT) task, and dual tasks involving word reading or category naming while performing a concurrent RT task. Results supported the general depletion of resources hypothesis: RT of the tinnitus group was slower in both conditions of the Stroop task, and in the word reading and category naming conditions of the dual task. Differences were not attributable to high frequency average hearing level, anxiety, or depression.

Forecasting the Occurrence of Severe Haze Events in Asia using Machine Learning Algorithms

NASA Astrophysics Data System (ADS)

Walton, A. L.

2016-12-01

Particulate pollution has become a serious environmental issue of many Asian countries in recent decades, threatening human health and frequently causing low visibility or haze days that interrupt from working, outdoor, and school activities to air, road, and sea transportation. To ultimately prevent such severe haze to occur requires many difficult tasks to be accomplished, dealing with trade and negotiation, emission control, energy consumption, transportation, land and plantation management, among other, of all involved countries or parties. Whereas, before these difficult measures could finally take place, it would be more practical to reduce the economic loss by developing skills to predict the occurrence of such events in reasonable accuracy so that effective mitigation or adaptation measures could be implemented ahead of time. The "traditional" numerical models developed based on fluid dynamics and explicit or parameterized representations of physiochemical processes can be certainly used for this task. However, the significant and sophisticated spatiotemporal variabilities associated with these events, the propagation of numerical or parameterization errors through model integration, and the computational demand all pose serious challenges to the practice of using these models to accomplish this interdisciplinary task. On the other hand, large quantity of meteorological, hydrological, atmospheric aerosol and composition, and surface visibility data from in-situ observation, reanalysis, or satellite retrievals, have become available to the community. These data might still not sufficient for evaluating and improving certain important aspects of the "traditional" models. Nevertheless, it is likely that these data can already support the effort to develop alternative "task-oriented" and computationally efficient forecasting skill using deep machine learning technique to avoid directly dealing with the sophisticated interplays across multiple process layers. I will present an experiential case of applying machine learning technique to predict the occurrence of severe haze events in Asia.

Forecasting the Occurrence of Severe Haze Events in Asia using Machine Learning Algorithms

NASA Astrophysics Data System (ADS)

Wang, C.

2017-12-01

Particulate pollution has become a serious environmental issue of many Asian countries in recent decades, threatening human health and frequently causing low visibility or haze days that interrupt from working, outdoor, and school activities to air, road, and sea transportation. To ultimately prevent such severe haze to occur requires many difficult tasks to be accomplished, dealing with trade and negotiation, emission control, energy consumption, transportation, land and plantation management, among other, of all involved countries or parties. Whereas, before these difficult measures could finally take place, it would be more practical to reduce the economic loss by developing skills to predict the occurrence of such events in reasonable accuracy so that effective mitigation or adaptation measures could be implemented ahead of time. The "traditional" numerical models developed based on fluid dynamics and explicit or parameterized representations of physiochemical processes can be certainly used for this task. However, the significant and sophisticated spatiotemporal variabilities associated with these events, the propagation of numerical or parameterization errors through model integration, and the computational demand all pose serious challenges to the practice of using these models to accomplish this interdisciplinary task. On the other hand, large quantity of meteorological, hydrological, atmospheric aerosol and composition, and surface visibility data from in-situ observation, reanalysis, or satellite retrievals, have become available to the community. These data might still not sufficient for evaluating and improving certain important aspects of the "traditional" models. Nevertheless, it is likely that these data can already support the effort to develop alternative "task-oriented" and computationally efficient forecasting skill using deep machine learning technique to avoid directly dealing with the sophisticated interplays across multiple process layers. I will present an experiential case of applying machine learning technique to predict the occurrence of severe haze events in Asia.

Modeling of functional trunk muscle performance: interfacing ergonomics and spine rehabilitation in response to the ADA.

PubMed

Khalaf, K A; Parnianpour, M; Sparto, P J; Simon, S R

1997-10-01

The combination of increasing costs of musculoskeletal injuries and the implementation of the Americans with Disabilities Act (ADA) has created the need for a more objective functional understanding of dynamic trunk performance. In this study, trunk extensor and flexor strengths were measured as a function of angular position and velocity for 20 subjects performing maximum isometric and isokinetic exertions. Results indicate that trunk strength is significantly influenced by trunk angular position, trunk angular velocity, gender, and direction, as well as by the interaction between trunk angular position and velocity. Three-dimensional surfaces of trunk strength in response to trunk angular position and velocity were constructed for each subject per direction. Such data presentation is more accurate and gives better insight about the strength profile of an individual than does the traditional use of a single strength value. The joint strength capacity profiles may be combined with joint torque requirements from a manual material handling task, such as a lifting task, to compute the dynamic utilization ratio for the trunk muscles. This ratio can be used as a unified measure of both task demand and functional capacity to guide job assignment, return to work, and prognosis during the rehabilitation processes. Furthermore, the strength regressions developed in this study would provide dynamic strength limits that can be used as functional constraints in the computer simulation of physical activities, such as lifting. In light of the ADA, this would be of great value in predicting the consequences of task modifications and/or workstation alterations without subjecting an injured worker or an individual with a disability to unnecessary testing.

Reflective Random Indexing and indirect inference: a scalable method for discovery of implicit connections.

PubMed

Cohen, Trevor; Schvaneveldt, Roger; Widdows, Dominic

2010-04-01

The discovery of implicit connections between terms that do not occur together in any scientific document underlies the model of literature-based knowledge discovery first proposed by Swanson. Corpus-derived statistical models of semantic distance such as Latent Semantic Analysis (LSA) have been evaluated previously as methods for the discovery of such implicit connections. However, LSA in particular is dependent on a computationally demanding method of dimension reduction as a means to obtain meaningful indirect inference, limiting its ability to scale to large text corpora. In this paper, we evaluate the ability of Random Indexing (RI), a scalable distributional model of word associations, to draw meaningful implicit relationships between terms in general and biomedical language. Proponents of this method have achieved comparable performance to LSA on several cognitive tasks while using a simpler and less computationally demanding method of dimension reduction than LSA employs. In this paper, we demonstrate that the original implementation of RI is ineffective at inferring meaningful indirect connections, and evaluate Reflective Random Indexing (RRI), an iterative variant of the method that is better able to perform indirect inference. RRI is shown to lead to more clearly related indirect connections and to outperform existing RI implementations in the prediction of future direct co-occurrence in the MEDLINE corpus. 2009 Elsevier Inc. All rights reserved.

A comparison of visuomotor cue integration strategies for object placement and prehension.

PubMed

Greenwald, Hal S; Knill, David C

2009-01-01

Visual cue integration strategies are known to depend on cue reliability and how rapidly the visual system processes incoming information. We investigated whether these strategies also depend on differences in the information demands for different natural tasks. Using two common goal-oriented tasks, prehension and object placement, we determined whether monocular and binocular information influence estimates of three-dimensional (3D) orientation differently depending on task demands. Both tasks rely on accurate 3D orientation estimates, but 3D position is potentially more important for grasping. Subjects placed an object on or picked up a disc in a virtual environment. On some trials, the monocular cues (aspect ratio and texture compression) and binocular cues (e.g., binocular disparity) suggested slightly different 3D orientations for the disc; these conflicts either were present upon initial stimulus presentation or were introduced after movement initiation, which allowed us to quantify how information from the cues accumulated over time. We analyzed the time-varying orientations of subjects' fingers in the grasping task and those of the object in the object placement task to quantify how different visual cues influenced motor control. In the first experiment, different subjects performed each task, and those performing the grasping task relied on binocular information more when orienting their hands than those performing the object placement task. When subjects in the second experiment performed both tasks in interleaved sessions, binocular cues were still more influential during grasping than object placement, and the different cue integration strategies observed for each task in isolation were maintained. In both experiments, the temporal analyses showed that subjects processed binocular information faster than monocular information, but task demands did not affect the time course of cue processing. How one uses visual cues for motor control depends on the task being performed, although how quickly the information is processed appears to be task invariant.

Training of resistance to proactive interference and working memory in older adults: a randomized double-blind study.

PubMed

Loosli, Sandra V; Falquez, Rosalux; Unterrainer, Josef M; Weiller, Cornelius; Rahm, Benjamin; Kaller, Christoph P

2016-03-01

Working memory (WM) performance is often decreased in older adults. Despite the growing popularity of WM trainings, underlying mechanisms are still poorly understood. Resistance to proactive interference (PI) constitutes a candidate process that contributes to WM performance and might influence training or transfer effects. Here, we investigated whether PI resistance can be enhanced in older adults using a WM training with specifically increased PI-demands. Further, we investigated whether potential effects of such a training were stable and entailed any transfer on non-trained tasks. Healthy old adults (N = 25, 68.8 ± 5.5 years) trained with a recent-probes and an n-back task daily for two weeks. Two different training regimens (high vs. low PI-amount in the tasks) were applied as between-participants manipulation, to which participants were randomly assigned. Near transfer tasks included interference tasks; far transfer tasks assessed fluid intelligence (gF) or speed. Immediate transfer was assessed directly after training; a follow-up measurement was conducted after two months. Both groups similarly improved in PI resistance in both training tasks. Thus, PI susceptibility was generally reduced in the two training groups and there was no difference between WM training with high versus low PI demands. Further, there was no differential near or far transfer on non-trained tasks, neither immediately after the training nor in the follow-up. PI-demands in WM training tasks do not seem critical for enhancing WM performance or PI resistance in older adults. Instead, improved resistance to PI appears to be an unspecific side-effect of a WM training.

Is Adaptation to Task Complexity Really Beneficial for Performance?

ERIC Educational Resources Information Center

Pieschl, Stephanie; Stahl, Elmar; Murray, Tom; Bromme, Rainer

2012-01-01

Theories of self-regulated learning assume that learners flexibly adapt their learning process to external task demands and that this is positively related to performance. In this study, university students (n = 119) solved three tasks that greatly differed in complexity. Their learning processes were captured in detail by task-specific…

Working Memory Costs of Task Switching

ERIC Educational Resources Information Center

Liefooghe, Baptist; Barrouillet, Pierre; Vandierendonck, Andre; Camos, Valerie

2008-01-01

Although many accounts of task switching emphasize the importance of working memory as a substantial source of the switch cost, there is a lack of evidence demonstrating that task switching actually places additional demands on working memory. The present study addressed this issue by implementing task switching in continuous complex span tasks…

The relationship between specific cognitive impairment and behaviour in Prader-Willi syndrome.

PubMed

Woodcock, K A; Oliver, C; Humphreys, G W

2011-02-01

Individuals with Prader-Willi syndrome (PWS) have been shown to demonstrate a particular cognitive deficit in attention switching and high levels of preference for routine and temper outbursts. This study assesses whether a specific pathway between a cognitive deficit and behaviour via environmental interaction can exist in individuals with PWS. Four individuals with PWS participated in a series of three single-case experiments including laboratory-based and natural environment designs. Cognitive (computer-based) challenges placed varying demands on attention switching or controlled for the cognitive demands of the tasks while placing no demands on switching. Unexpected changes to routines or expectations were presented in controlled games, or imposed on participants' natural environments and compared with control conditions during which no unexpected changes occurred. Behaviour was observed and heart rate was measured. Participants showed significantly increased temper outburst related behaviours during cognitive challenges that placed demands on attention switching, relative to the control cognitive challenges. Participants showed significantly increased temper outburst related behaviours when unexpected changes occurred in an experimental or the natural environment compared with when no changes occurred. Difficult behaviours that could be triggered reliably in an individual by a specific cognitive demand could also be triggered via manipulation of the environment. Results suggest that a directional relationship between a specific cognitive deficit and behaviour, via environmental interaction, can exist in individuals with PWS. © 2011 The Authors. Journal of Intellectual Disability Research © 2011 Blackwell Publishing Ltd.

Effects of Panax ginseng, consumed with and without glucose, on blood glucose levels and cognitive performance during sustained 'mentally demanding' tasks.

PubMed

Reay, Jonathon L; Kennedy, David O; Scholey, Andrew B

2006-11-01

Single doses of the traditional herbal treatment Panax ginseng have recently been shown to lower blood glucose levels and elicit cognitive improvements in healthy, overnight-fasted volunteers. The specific mechanisms responsible for these effects are not known. However, cognitive improvements may be related to the glycaemic properties of Panax ginseng. Using a double-blind, placebo-controlled, balanced-crossover design, 27 healthy young adults completed a 10 minute "cognitive demand" test battery at baseline. They then consumed capsules containing either ginseng (extract G115) or a placebo and 30 minutes later a drink containing glucose or placebo. A further 30 minutes later (i.e. 60 minutes post-baseline/capsules) they completed the "cognitive demand" battery six times in immediate succession. Depending on the condition to which the participant was allocated on that particular day, the combination of capsules/drink treatments corresponded to a dose of: 0mg G115/0 mg glucose (placebo); 200mg G115/0 mg glucose (ginseng); 0 mg G115/25 g glucose (glucose) or 200 mg G115/25 g glucose (ginseng/glucose combination). The 10 minute "cognitive demand" battery comprised a Serial Threes subtraction task (2 min); a Serial Sevens subtraction task (2 min); a Rapid Visual Information Processing task (5 min); and a "mental fatigue" visual analogue scale. Blood glucose levels were measured prior to the day's treatment, and before and after the post-dose completions of the battery. The results showed that both Panax ginseng and glucose enhanced performance of a mental arithmetic task and ameliorated the increase in subjective feelings of mental fatigue experienced by participants during the later stages of the sustained, cognitively demanding task performance. Accuracy of performing the Rapid Visual Information Processing task (RVIP) was also improved following the glucose load. There was no evidence of a synergistic relationship between Panax ginseng and exogenous glucose ingestion on any cognitive outcome measure. Panax ginseng caused a reduction in blood glucose levels 1 hour following consumption when ingested without glucose. These results confirm that Panax ginseng may possess glucoregulatory properties and can enhance cognitive performance.

Governance Practice in English Further Education Colleges: The Purpose of Further Education Governance and the Changing Role of Standards Committee Governors

ERIC Educational Resources Information Center

Masunga, Robert

2013-01-01

This article explores the purpose of governance in the further education (FE) sector in England and the increasing tasks demands that are expected from the governors of standards committees (SC) as part of their changing role. It will then examine how these task demands impact SC governors' perceptions of FE governance. This research is done at a…

Using near infrared spectroscopy and heart rate variability to detect mental overload.

PubMed

Durantin, G; Gagnon, J-F; Tremblay, S; Dehais, F

2014-02-01

Mental workload is a key factor influencing the occurrence of human error, especially during piloting and remotely operated vehicle (ROV) operations, where safety depends on the ability of pilots to act appropriately. In particular, excessively high or low mental workload can lead operators to neglect critical information. The objective of the present study is to investigate the potential of functional near infrared spectroscopy (fNIRS) - a non-invasive method of measuring prefrontal cortex activity - in combination with measurements of heart rate variability (HRV), to predict mental workload during a simulated piloting task, with particular regard to task engagement and disengagement. Twelve volunteers performed a computer-based piloting task in which they were asked to follow a dynamic target with their aircraft, a task designed to replicate key cognitive demands associated with real life ROV operating tasks. In order to cover a wide range of mental workload levels, task difficulty was manipulated in terms of processing load and difficulty of control - two critical sources of workload associated with piloting and remotely operating a vehicle. Results show that both fNIRS and HRV are sensitive to different levels of mental workload; notably, lower prefrontal activation as well as a lower LF/HF ratio at the highest level of difficulty, suggest that these measures are suitable for mental overload detection. Moreover, these latter measurements point toward the existence of a quadratic model of mental workload. Copyright © 2013 Elsevier B.V. All rights reserved.

Spatial learning while navigating with severely degraded viewing: The role of attention and mobility monitoring

PubMed Central

Rand, Kristina M.; Creem-Regehr, Sarah H.; Thompson, William B.

2015-01-01

The ability to navigate without getting lost is an important aspect of quality of life. In five studies, we evaluated how spatial learning is affected by the increased demands of keeping oneself safe while walking with degraded vision (mobility monitoring). We proposed that safe low-vision mobility requires attentional resources, providing competition for those needed to learn a new environment. In Experiments 1 and 2 participants navigated along paths in a real-world indoor environment with simulated degraded vision or normal vision. Memory for object locations seen along the paths was better with normal compared to degraded vision. With degraded vision, memory was better when participants were guided by an experimenter (low monitoring demands) versus unguided (high monitoring demands). In Experiments 3 and 4, participants walked while performing an auditory task. Auditory task performance was superior with normal compared to degraded vision. With degraded vision, auditory task performance was better when guided compared to unguided. In Experiment 5, participants performed both the spatial learning and auditory tasks under degraded vision. Results showed that attention mediates the relationship between mobility-monitoring demands and spatial learning. These studies suggest that more attention is required and spatial learning is impaired when navigating with degraded viewing. PMID:25706766

Stress and eating: the effects of ego-threat and cognitive demand on food intake in restrained and emotional eaters.

PubMed

Wallis, D J; Hetherington, M M

2004-08-01

Restrained and emotional eaters overeat in response to stress. To compare differential effects of cognitive demand and ego-threatening stressors on subsequent chocolate intake, 38 females completed a neutral (control), an ego threatening and an incongruent Stroop colour-naming task on three separate occasions. Participants were assigned to four groups based on median-split scores on the restrained and emotional eating scales of the Dutch Eating Behaviour Questionnaire-high restraint/high emotional, high restraint/low emotional, low restraint/high emotional and low restraint/low emotional. Higher response latencies were observed in the incongruent task, confirming its greater cognitive (attentional) demand. Overall intake was enhanced by 23% after ego-threat and 15% after the incongruent Stroop task relative to control. Restraint was associated with greater intake after both ego-threat and the incongruent task than in the control condition. In contrast, emotional eating was associated with greater intake after only the ego-threat, relative to control. A positive association between reaction time and subsequent intake in all conditions for high restraint/low emotional eaters provided support for the limited capacity hypothesis. Enhanced intake in emotional eaters is proposed to relate to escape from self-awareness. These findings demonstrate differential effects of threat and demand on stress-related eating in restrained and emotional eaters.

The influence of aging and attentional demands on recovery from postural instability.

PubMed

Stelmach, G E; Zelaznik, H N; Lowe, D

1990-06-01

It is well known that the risk of a debilitating injury from a fall is much higher for elderly than for young individuals. In addition, it is well documented that healthy elderly subjects exhibit increased postural sway during normal stance tasks. In the present experiment, we explored the notion that control of minor postural instability in elderly subjects is attention demanding. Postural sway of eight elderly (mean age = 70.0 years) and eight young (mean age = 20.0 years) subjects was measured under two different secondary demands during stable and mildly unstable upright stance. There were two types of work loads. Either a cognitive (math task) or motor (hand-squeeze) task was performed during the second segment of a 50-second standing trial. The effect of these work loads on mean velocity, range, and variability of range of center of foot pressure was measured during the destabilizing activity of arm swinging and subsequent recovery period. Following seven seconds of 1 Hz arm-swinging activity, elderly subjects showed a marked increase in recovery time to normal stance when concurrently performing an arithmetic task. This result suggests that recovery from a posturally destabilizing activity, involving proprioceptive and vestibular information, places increased attentional demands on the postural support system of the elderly.

Decision Making in Concurrent Multitasking: Do People Adapt to Task Interference?

PubMed Central

Nijboer, Menno; Taatgen, Niels A.; Brands, Annelies; Borst, Jelmer P.; van Rijn, Hedderik

2013-01-01

While multitasking has received a great deal of attention from researchers, we still know little about how well people adapt their behavior to multitasking demands. In three experiments, participants were presented with a multicolumn subtraction task, which required working memory in half of the trials. This primary task had to be combined with a secondary task requiring either working memory or visual attention, resulting in different types of interference. Before each trial, participants were asked to choose which secondary task they wanted to perform concurrently with the primary task. We predicted that if people seek to maximize performance or minimize effort required to perform the dual task, they choose task combinations that minimize interference. While performance data showed that the predicted optimal task combinations indeed resulted in minimal interference between tasks, the preferential choice data showed that a third of participants did not show any adaptation, and for the remainder it took a considerable number of trials before the optimal task combinations were chosen consistently. On the basis of these results we argue that, while in principle people are able to adapt their behavior according to multitasking demands, selection of the most efficient combination of strategies is not an automatic process. PMID:24244527