Detecting gait abnormalities after concussion or mild traumatic brain injury: A systematic review of single-task, dual-task, and complex gait.

PubMed

Fino, Peter C; Parrington, Lucy; Pitt, Will; Martini, Douglas N; Chesnutt, James C; Chou, Li-Shan; King, Laurie A

2018-05-01

While a growing number of studies have investigated the effects of concussion or mild traumatic brain injury (mTBI) on gait, many studies use different experimental paradigms and outcome measures. The path for translating experimental studies for objective clinical assessments of gait is unclear. This review asked 2 questions: 1) is gait abnormal after concussion/mTBI, and 2) what gait paradigms (single-task, dual-task, complex gait) detect abnormalities after concussion. Data sources included MEDLINE/PubMed, Scopus, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) accessed on March 14, 2017. Original research articles reporting gait outcomes in people with concussion or mTBI were included. Studies of moderate, severe, or unspecified TBI, and studies without a comparator were excluded. After screening 233 articles, 38 studies were included and assigned to one or more sections based on the protocol and reported outcomes. Twenty-six articles reported single-task simple gait outcomes, 24 reported dual-task simple gait outcomes, 21 reported single-task complex gait outcomes, and 10 reported dual-task complex gait outcomes. Overall, this review provides evidence for two conclusions: 1) gait is abnormal acutely after concussion/mTBI but generally resolves over time; and 2) the inconsistency of findings, small sample sizes, and small number of studies examining homogenous measures at the same time-period post-concussion highlight the need for replication across independent populations and investigators. Future research should concentrate on dual-task and complex gait tasks, as they showed promise for detecting abnormal locomotor function outside of the acute timeframe. Additionally, studies should provide detailed demographic and clinical characteristics to enable more refined comparisons across studies. Copyright © 2018 Elsevier B.V. All rights reserved.

The "EyeCane", a new electronic travel aid for the blind: Technology, behavior & swift learning.

PubMed

Maidenbaum, Shachar; Hanassy, Shlomi; Abboud, Sami; Buchs, Galit; Chebat, Daniel-Robert; Levy-Tzedek, Shelly; Amedi, Amir

2014-01-01

Independent mobility is one of the most pressing problems facing people who are blind. We present the EyeCane, a new mobility aid aimed at increasing perception of environment beyond what is provided by the traditional White Cane for tasks such as distance estimation, navigation and obstacle detection. The "EyeCane" enhances the traditional White Cane by using tactile and auditory output to increase detectable distance and angles. It circumvents the technical pitfalls of other devices, such as weight, short battery life, complex interface schemes, and slow learning curve. It implements multiple beams to enables detection of obstacles at different heights, and narrow beams to provide active sensing that can potentially increase the user's spatial perception of the environment. Participants were tasked with using the EyeCane for several basic tasks with minimal training. Blind and blindfolded-sighted participants were able to use the EyeCane successfully for distance estimation, simple navigation and simple obstacle detection after only several minutes of training. These results demonstrate the EyeCane's potential for mobility rehabilitation. The short training time is especially important since available mobility training resources are limited, not always available, and can be quite expensive and/or entail long waiting periods.

Detection of Alkylating Agents using Electrical and Mechanical Means

NASA Astrophysics Data System (ADS)

Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir; Eichen, Yoav

2011-08-01

Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

What you fear will appear: detection of schematic spiders in spider fear.

PubMed

Peira, Nathalie; Golkar, Armita; Larsson, Maria; Wiens, Stefan

2010-01-01

Various experimental tasks suggest that fear guides attention. However, because these tasks often lack ecological validity, it is unclear to what extent results from these tasks can be generalized to real-life situations. In change detection tasks, a brief interruption of the visual input (i.e., a blank interval or a scene cut) often results in undetected changes in the scene. This setup resembles real-life viewing behavior and is used here to increase ecological validity of the attentional task without compromising control over the stimuli presented. Spider-fearful and nonfearful women detected schematic spiders and flowers that were added to one of two identical background pictures that alternated with a brief blank in between them (i.e., flicker paradigm). Results showed that spider-fearful women detected spiders (but not flowers) faster than did nonfearful women. Because spiders and flowers had similar low-level features, these findings suggest that fear guides attention on the basis of object features rather than simple low-level features.

Individual Differences in Dual Task Performance.

DTIC Science & Technology

1981-06-10

SJCURITY CLASSIFICATION OF THIS PAGE("en Data Entered) second experimental series, we compared ability to detect visual and audi- tory targets in single...used performance on a simple secondary task executed during an easy primary task to predict performance on a more diffi- cult’version of the same...process concepts developed b’j cognitive ps:choloqists°’ In this laborators, we adapted a number of experimental tasks to 4ield individual measures of the

SIMON: A Simple Instructional Monitor. Technical Report.

ERIC Educational Resources Information Center

Feurzeig, Wallace; And Others

An instructional monitor is a program which tries to detect, diagnose, and possibly help overcome a student's learning difficulties in the course of solving a problem or performing a task. In one approach to building an instructional monitor, the student uses a special task- or problem-oriented language expressly designed around some particular…

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

Task-related enhancement in corticomotor excitability during haptic sensing with the contra- or ipsilateral hand in young and senior adults.

PubMed

Master, Sabah; Tremblay, François

2012-03-14

Haptic sensing with the fingers represents a unique class of manipulative actions, engaging motor, somatosensory and associative areas of the cortex while requiring only minimal forces and relatively simple movement patterns. Using transcranial magnetic stimulation (TMS), we investigated task-related changes in motor evoked potential (MEP) amplitude associated with unimanual haptic sensing in two related experiments. In Experiment I, we contrasted changes in the excitability of the hemisphere controlling the task hand in young and old adults under two trial conditions, i.e. when participants either touched a fine grating (smooth trials) or touched a coarse grating to detect its groove orientation (grating trials). In Experiment II, the same contrast between tasks was performed but with TMS applied over the hemisphere controlling the resting hand, while also addressing hemispheric (right vs. left) and age differences. In Experiment I, a main effect of trial type on MEP amplitude was detected (p = 0.001), MEPs in the task hand being ~50% larger during grating than smooth trials. No interaction with age was detected. Similar results were found for Experiment II, trial type having a large effect on MEP amplitude in the resting hand (p < 0.001) owing to selective increase in MEP size (~2.6 times greater) for grating trials. No interactions with age or side (right vs. left) were detected. Collectively, these results indicate that adding a haptic component to a simple unilateral finger action can elicit robust corticomotor facilitation not only in the working hemisphere but also in the opposite hemisphere. The fact that this facilitation seems well preserved with age, when task difficulty is adjusted, has some potential clinical implications.

Improving Sensitivity to Detect Mild Cognitive Impairment: Cognitive Load Dual-Task Gait Speed Assessment.

PubMed

MacAulay, Rebecca K; Wagner, Mark T; Szeles, Dana; Milano, Nicholas J

2017-07-01

Longitudinal research indicates that cognitive load dual-task gait assessment is predictive of cognitive decline and thus might provide a sensitive measure to screen for mild cognitive impairment (MCI). However, research among older adults being clinically evaluated for cognitive concerns, a defining feature of MCI, is lacking. The present study investigated the effect of performing a cognitive task on normal walking speed in patients presenting to a memory clinic with cognitive complaints. Sixty-one patients with a mean age of 68 years underwent comprehensive neuropsychological testing, clinical interview, and gait speed (simple- and dual-task conditions) assessments. Thirty-four of the 61 patients met criteria for MCI. Repeated measure analyses of covariance revealed that greater age and MCI both significantly associated with slower gait speed, ps<.05. Follow-up analysis indicated that the MCI group had significantly slower dual-task gait speed but did not differ in simple-gait speed. Multivariate linear regression across groups found that executive attention performance accounted for 27.4% of the variance in dual-task gait speed beyond relevant demographic and health risk factors. The present study increases the external validity of dual-task gait assessment of MCI. Differences in dual-task gait speed appears to be largely attributable to executive attention processes. These findings have clinical implications as they demonstrate expected patterns of gait-brain behavior relationships in response to a cognitive dual task within a clinically representative population. Cognitive load dual-task gait assessment may provide a cost efficient and sensitive measure to detect older adults at high risk of a dementia disorder. (JINS, 2017, 23, 493-501).

Uncovering beat deafness: detecting rhythm disorders with synchronized finger tapping and perceptual timing tasks.

PubMed

Dalla Bella, Simone; Sowiński, Jakub

2015-03-16

A set of behavioral tasks for assessing perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) is presented here with the goal of uncovering rhythm disorders, such as beat deafness. Beat deafness is characterized by poor performance in perceiving durations in auditory rhythmic patterns or poor synchronization of movement with auditory rhythms (e.g., with musical beats). These tasks include the synchronization of finger tapping to the beat of simple and complex auditory stimuli and the detection of rhythmic irregularities (anisochrony detection task) embedded in the same stimuli. These tests, which are easy to administer, include an assessment of both perceptual and sensorimotor timing abilities under different conditions (e.g., beat rates and types of auditory material) and are based on the same auditory stimuli, ranging from a simple metronome to a complex musical excerpt. The analysis of synchronized tapping data is performed with circular statistics, which provide reliable measures of synchronization accuracy (e.g., the difference between the timing of the taps and the timing of the pacing stimuli) and consistency. Circular statistics on tapping data are particularly well-suited for detecting individual differences in the general population. Synchronized tapping and anisochrony detection are sensitive measures for identifying profiles of rhythm disorders and have been used with success to uncover cases of poor synchronization with spared perceptual timing. This systematic assessment of perceptual and sensorimotor timing can be extended to populations of patients with brain damage, neurodegenerative diseases (e.g., Parkinson's disease), and developmental disorders (e.g., Attention Deficit Hyperactivity Disorder).

Change in hippocampal theta activity with transfer from simple discrimination tasks to a simultaneous feature-negative task

PubMed Central

Sakimoto, Yuya; Sakata, Shogo

2014-01-01

It was showed that solving a simple discrimination task (A+, B−) and a simultaneous feature-negative (FN) task (A+, AB−) used the hippocampal-independent strategy. Recently, we showed that the number of sessions required for a rat to completely learn a task differed between the FN and simple discrimination tasks, and there was a difference in hippocampal theta activity between these tasks. These results suggested that solving the FN task relied on a different strategy than the simple discrimination task. In this study, we provided supportive evidence that solving the FN and simple discrimination tasks involved different strategies by examining changes in performance and hippocampal theta activity in the FN task after transfer from the simple discrimination task (A+, B− → A+, AB−). The results of this study showed that performance on the FN task was impaired and there was a difference in hippocampal theta activity between the simple discrimination task and FN task. Thus, we concluded that solving the FN task uses a different strategy than the simple discrimination task. PMID:24917797

Proactive Interference Does Not Meaningfully Distort Visual Working Memory Capacity Estimates in the Canonical Change Detection Task

PubMed Central

Lin, Po-Han; Luck, Steven J.

2012-01-01

The change detection task has become a standard method for estimating the storage capacity of visual working memory. Most researchers assume that this task isolates the properties of an active short-term storage system that can be dissociated from long-term memory systems. However, long-term memory storage may influence performance on this task. In particular, memory traces from previous trials may create proactive interference that sometimes leads to errors, thereby reducing estimated capacity. Consequently, the capacity of visual working memory may be higher than is usually thought, and correlations between capacity and other measures of cognition may reflect individual differences in proactive interference rather than individual differences in the capacity of the short-term storage system. Indeed, previous research has shown that change detection performance can be influenced by proactive interference under some conditions. The purpose of the present study was to determine whether the canonical version of the change detection task – in which the to-be-remembered information consists of simple, briefly presented features – is influenced by proactive interference. Two experiments were conducted using methods that ordinarily produce substantial evidence of proactive interference, but no proactive interference was observed. Thus, the canonical version of the change detection task can be used to assess visual working memory capacity with no meaningful influence of proactive interference. PMID:22403556

Proactive interference does not meaningfully distort visual working memory capacity estimates in the canonical change detection task.

PubMed

Lin, Po-Han; Luck, Steven J

2012-01-01

The change detection task has become a standard method for estimating the storage capacity of visual working memory. Most researchers assume that this task isolates the properties of an active short-term storage system that can be dissociated from long-term memory systems. However, long-term memory storage may influence performance on this task. In particular, memory traces from previous trials may create proactive interference that sometimes leads to errors, thereby reducing estimated capacity. Consequently, the capacity of visual working memory may be higher than is usually thought, and correlations between capacity and other measures of cognition may reflect individual differences in proactive interference rather than individual differences in the capacity of the short-term storage system. Indeed, previous research has shown that change detection performance can be influenced by proactive interference under some conditions. The purpose of the present study was to determine whether the canonical version of the change detection task - in which the to-be-remembered information consists of simple, briefly presented features - is influenced by proactive interference. Two experiments were conducted using methods that ordinarily produce substantial evidence of proactive interference, but no proactive interference was observed. Thus, the canonical version of the change detection task can be used to assess visual working memory capacity with no meaningful influence of proactive interference.

Estimated capacity of object files in visual short-term memory is not improved by retrieval cueing.

PubMed

Saiki, Jun; Miyatsuji, Hirofumi

2009-03-23

Visual short-term memory (VSTM) has been claimed to maintain three to five feature-bound object representations. Some results showing smaller capacity estimates for feature binding memory have been interpreted as the effects of interference in memory retrieval. However, change-detection tasks may not properly evaluate complex feature-bound representations such as triple conjunctions in VSTM. To understand the general type of feature-bound object representation, evaluation of triple conjunctions is critical. To test whether interference occurs in memory retrieval for complete object file representations in a VSTM task, we cued retrieval in novel paradigms that directly evaluate the memory for triple conjunctions, in comparison with a simple change-detection task. In our multiple object permanence tracking displays, observers monitored for a switch in feature combination between objects during an occlusion period, and we found that a retrieval cue provided no benefit with the triple conjunction tasks, but significant facilitation with the change-detection task, suggesting that low capacity estimates of object file memory in VSTM reflect a limit on maintenance, not retrieval.

Fast learning of simple perceptual discriminations reduces brain activation in working memory and in high-level auditory regions.

PubMed

Daikhin, Luba; Ahissar, Merav

2015-07-01

Introducing simple stimulus regularities facilitates learning of both simple and complex tasks. This facilitation may reflect an implicit change in the strategies used to solve the task when successful predictions regarding incoming stimuli can be formed. We studied the modifications in brain activity associated with fast perceptual learning based on regularity detection. We administered a two-tone frequency discrimination task and measured brain activation (fMRI) under two conditions: with and without a repeated reference tone. Although participants could not explicitly tell the difference between these two conditions, the introduced regularity affected both performance and the pattern of brain activation. The "No-Reference" condition induced a larger activation in frontoparietal areas known to be part of the working memory network. However, only the condition with a reference showed fast learning, which was accompanied by a reduction of activity in two regions: the left intraparietal area, involved in stimulus retention, and the posterior superior-temporal area, involved in representing auditory regularities. We propose that this joint reduction reflects a reduction in the need for online storage of the compared tones. We further suggest that this change reflects an implicit strategic shift "backwards" from reliance mainly on working memory networks in the "No-Reference" condition to increased reliance on detected regularities stored in high-level auditory networks.

The Comparison of Visual Working Memory Representations with Perceptual Inputs

PubMed Central

Hyun, Joo-seok; Woodman, Geoffrey F.; Vogel, Edward K.; Hollingworth, Andrew

2008-01-01

The human visual system can notice differences between memories of previous visual inputs and perceptions of new visual inputs, but the comparison process that detects these differences has not been well characterized. This study tests the hypothesis that differences between the memory of a stimulus array and the perception of a new array are detected in a manner that is analogous to the detection of simple features in visual search tasks. That is, just as the presence of a task-relevant feature in visual search can be detected in parallel, triggering a rapid shift of attention to the object containing the feature, the presence of a memory-percept difference along a task-relevant dimension can be detected in parallel, triggering a rapid shift of attention to the changed object. Supporting evidence was obtained in a series of experiments that examined manual reaction times, saccadic reaction times, and event-related potential latencies. However, these experiments also demonstrated that a slow, limited-capacity process must occur before the observer can make a manual change-detection response. PMID:19653755

Latent error detection: A golden two hours for detection.

PubMed

Saward, Justin R E; Stanton, Neville A

2017-03-01

Undetected error in safety critical contexts generates a latent condition that can contribute to a future safety failure. The detection of latent errors post-task completion is observed in naval air engineers using a diary to record work-related latent error detection (LED) events. A systems view is combined with multi-process theories to explore sociotechnical factors associated with LED. Perception of cues in different environments facilitates successful LED, for which the deliberate review of past tasks within two hours of the error occurring and whilst remaining in the same or similar sociotechnical environment to that which the error occurred appears most effective. Identified ergonomic interventions offer potential mitigation for latent errors; particularly in simple everyday habitual tasks. It is thought safety critical organisations should look to engineer further resilience through the application of LED techniques that engage with system cues across the entire sociotechnical environment, rather than relying on consistent human performance. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Raised visual detection thresholds depend on the level of complexity of cognitive foveal loading.

PubMed

Plainis, S; Murray, I J; Chauhan, K

2001-01-01

The objective of the study was to measure the interactions between visual thresholds for a simple light (the secondary task) presented peripherally and a simultaneously performed cognitive task (the primary task) presented foveally The primary task was highly visible but varied according to its cognitive complexity. Interactions between the tasks were determined by measuring detection thresholds for the peripheral task and accuracy of performance of the foveal task. Effects were measured for 5, 10, 20, and 30 deg eccentricity of the peripherally presented light and for three levels of cognitive complexity. Mesopic conditions (0.5 lx) were used. As expected, the concurrent presentation of the foveal cognitive task reduced peripheral sensitivity. Moreover, performance of the foveal task was adversely affected when conducting the peripheral task. Performance on both tasks was reduced as the level of complexity of the cognitive task increased. There were qualitative differences in task interactions between the central 10 deg and at greater eccentricities. Within 10 deg there was a disproportionate effect of eccentricity, previously interpreted as the 'tunnel-vision' model of visual field narrowing. Interactions outside 10 deg were less affected by eccentricity. These results are discussed in terms of the known neurophysiological characteristics of the primary visual pathway.

Selective tuning of the right inferior frontal gyrus during target detection

PubMed Central

Hampshire, Adam; Thompson, Russell; Duncan, John; Owen, Adrian M.

2010-01-01

In the human brain, a network of frontal and parietal regions is commonly recruited during tasks that demand the deliberate, focused control of thought and action. Previously, using a simple target detection task, we reported striking differences in the selectivity of the BOLD response in anatomically distinct subregions of this network. In particular, it was observed that the right inferior frontal gyrus (IFG) followed a tightly tuned function, selectively responding only to the current target object. Here, we examine this functional specialization further, using adapted versions of our original task. Our results demonstrate that the response of the right IFG to targets is a strong and replicable phenomenon. It occurs under increased attentional load, when targets and distractors are equally frequent, and when controlling for inhibitory processes. These findings support the hypothesis that the right IFG responds selectively to those items that are of the most relevance to the currently intended task schema. PMID:19246331

Functional connectivity supporting the selective maintenance of feature-location binding in visual working memory

PubMed Central

Takahama, Sachiko; Saiki, Jun

2014-01-01

Information on an object's features bound to its location is very important for maintaining object representations in visual working memory. Interactions with dynamic multi-dimensional objects in an external environment require complex cognitive control, including the selective maintenance of feature-location binding. Here, we used event-related functional magnetic resonance imaging to investigate brain activity and functional connectivity related to the maintenance of complex feature-location binding. Participants were required to detect task-relevant changes in feature-location binding between objects defined by color, orientation, and location. We compared a complex binding task requiring complex feature-location binding (color-orientation-location) with a simple binding task in which simple feature-location binding, such as color-location, was task-relevant and the other feature was task-irrelevant. Univariate analyses showed that the dorsolateral prefrontal cortex (DLPFC), hippocampus, and frontoparietal network were activated during the maintenance of complex feature-location binding. Functional connectivity analyses indicated cooperation between the inferior precentral sulcus (infPreCS), DLPFC, and hippocampus during the maintenance of complex feature-location binding. In contrast, the connectivity for the spatial updating of simple feature-location binding determined by reanalyzing the data from Takahama et al. (2010) demonstrated that the superior parietal lobule (SPL) cooperated with the DLPFC and hippocampus. These results suggest that the connectivity for complex feature-location binding does not simply reflect general memory load and that the DLPFC and hippocampus flexibly modulate the dorsal frontoparietal network, depending on the task requirements, with the infPreCS involved in the maintenance of complex feature-location binding and the SPL involved in the spatial updating of simple feature-location binding. PMID:24917833

Functional connectivity supporting the selective maintenance of feature-location binding in visual working memory.

PubMed

Takahama, Sachiko; Saiki, Jun

2014-01-01

Information on an object's features bound to its location is very important for maintaining object representations in visual working memory. Interactions with dynamic multi-dimensional objects in an external environment require complex cognitive control, including the selective maintenance of feature-location binding. Here, we used event-related functional magnetic resonance imaging to investigate brain activity and functional connectivity related to the maintenance of complex feature-location binding. Participants were required to detect task-relevant changes in feature-location binding between objects defined by color, orientation, and location. We compared a complex binding task requiring complex feature-location binding (color-orientation-location) with a simple binding task in which simple feature-location binding, such as color-location, was task-relevant and the other feature was task-irrelevant. Univariate analyses showed that the dorsolateral prefrontal cortex (DLPFC), hippocampus, and frontoparietal network were activated during the maintenance of complex feature-location binding. Functional connectivity analyses indicated cooperation between the inferior precentral sulcus (infPreCS), DLPFC, and hippocampus during the maintenance of complex feature-location binding. In contrast, the connectivity for the spatial updating of simple feature-location binding determined by reanalyzing the data from Takahama et al. (2010) demonstrated that the superior parietal lobule (SPL) cooperated with the DLPFC and hippocampus. These results suggest that the connectivity for complex feature-location binding does not simply reflect general memory load and that the DLPFC and hippocampus flexibly modulate the dorsal frontoparietal network, depending on the task requirements, with the infPreCS involved in the maintenance of complex feature-location binding and the SPL involved in the spatial updating of simple feature-location binding.

The effect of increased monitoring load on vigilance performance using a simulated radar display.

DOT National Transportation Integrated Search

1977-07-01

The present study examined the extent to which level of target density influences the ability to sustain attention to a complex monitoring task requiring only a detection response to simple stimulus change. The visual display was designed to approxim...

Pitch discrimination by ferrets for simple and complex sounds.

PubMed

Walker, Kerry M M; Schnupp, Jan W H; Hart-Schnupp, Sheelah M B; King, Andrew J; Bizley, Jennifer K

2009-09-01

Although many studies have examined the performance of animals in detecting a frequency change in a sequence of tones, few have measured animals' discrimination of the fundamental frequency (F0) of complex, naturalistic stimuli. Additionally, it is not yet clear if animals perceive the pitch of complex sounds along a continuous, low-to-high scale. Here, four ferrets (Mustela putorius) were trained on a two-alternative forced choice task to discriminate sounds that were higher or lower in F0 than a reference sound using pure tones and artificial vowels as stimuli. Average Weber fractions for ferrets on this task varied from approximately 20% to 80% across references (200-1200 Hz), and these fractions were similar for pure tones and vowels. These thresholds are approximately ten times higher than those typically reported for other mammals on frequency change detection tasks that use go/no-go designs. Naive human listeners outperformed ferrets on the present task, but they showed similar effects of stimulus type and reference F0. These results suggest that while non-human animals can be trained to label complex sounds as high or low in pitch, this task may be much more difficult for animals than simply detecting a frequency change.

Detection and classification of underwater targets by echolocating dolphins

NASA Astrophysics Data System (ADS)

Au, Whitlow

2003-10-01

Many experiments have been performed with echolocating dolphins to determine their target detection and discrimination capabilities. Target detection experiments have been performed in a naturally noisy environment, with masking noise and with both phantom echoes and masking noise, and in reverberation. The echo energy to rms noise spectral density for the Atlantic bottlenose dolphin (Tursiops truncatus) at the 75% correct response threshold is approximately 7.5 dB whereas for the beluga whale (Delphinapterus leucas) the threshold is approximately 1 dB. The dolphin's detection threshold in reverberation is approximately 2.5 dB vs 2 dB for the beluga. The difference in performance between species can probably be ascribed to differences in how both species perceived the task. The bottlenose dolphin may be performing a combination detection/discrimination task whereas the beluga may be performing a simple detection task. Echolocating dolphins also have the capability to make fine discriminate of target properties such as wall thickness difference of water-filled cylinders and material differences in metallic plates. The high resolution property of the animal's echolocation signals and the high dynamic range of its auditory system are important factors in their outstanding discrimination capabilities.

The role of extra-foveal processing in 3D imaging

NASA Astrophysics Data System (ADS)

Eckstein, Miguel P.; Lago, Miguel A.; Abbey, Craig K.

2017-03-01

The field of medical image quality has relied on the assumption that metrics of image quality for simple visual detection tasks are a reliable proxy for the more clinically realistic visual search tasks. Rank order of signal detectability across conditions often generalizes from detection to search tasks. Here, we argue that search in 3D images represents a paradigm shift in medical imaging: radiologists typically cannot exhaustively scrutinize all regions of interest with the high acuity fovea requiring detection of signals with extra-foveal areas (visual periphery) of the human retina. We hypothesize that extra-foveal processing can alter the detectability of certain types of signals in medical images with important implications for search in 3D medical images. We compare visual search of two different types of signals in 2D vs. 3D images. We show that a small microcalcification-like signal is more highly detectable than a larger mass-like signal in 2D search, but its detectability largely decreases (relative to the larger signal) in the 3D search task. Utilizing measurements of observer detectability as a function retinal eccentricity and observer eye fixations we can predict the pattern of results in the 2D and 3D search studies. Our findings: 1) suggest that observer performance findings with 2D search might not always generalize to 3D search; 2) motivate the development of a new family of model observers that take into account the inhomogeneous visual processing across the retina (foveated model observers).

Psychophysical and perceptual performance in a simulated-scotoma model of human eye injury

NASA Astrophysics Data System (ADS)

Brandeis, R.; Egoz, I.; Peri, D.; Sapiens, N.; Turetz, J.

2008-02-01

Macular scotomas, affecting visual functioning, characterize many eye and neurological diseases like AMD, diabetes mellitus, multiple sclerosis, and macular hole. In this work, foveal visual field defects were modeled, and their effects were evaluated on spatial contrast sensitivity and a task of stimulus detection and aiming. The modeled occluding scotomas, of different size, were superimposed on the stimuli presented on the computer display, and were stabilized on the retina using a mono Purkinje Eye-Tracker. Spatial contrast sensitivity was evaluated using square-wave grating stimuli, whose contrast thresholds were measured using the method of constant stimuli with "catch trials". The detection task consisted of a triple conjunctive visual search display of: size (in visual angle), contrast and background (simple, low-level features vs. complex, high-level features). Search/aiming accuracy as well as R.T. measures used for performance evaluation. Artificially generated scotomas suppressed spatial contrast sensitivity in a size dependent manner, similar to previous studies. Deprivation effect was dependent on spatial frequency, consistent with retinal inhomogeneity models. Stimulus detection time was slowed in complex background search situation more than in simple background. Detection speed was dependent on scotoma size and size of stimulus. In contrast, visually guided aiming was more sensitive to scotoma effect in simple background search situation than in complex background. Both stimulus aiming R.T. and accuracy (precision targeting) were impaired, as a function of scotoma size and size of stimulus. The data can be explained by models distinguishing between saliency-based, parallel and serial search processes, guiding visual attention, which are supported by underlying retinal as well as neural mechanisms.

The impact of secondary-task type on the sensitivity of reaction-time based measurement of cognitive load for novices learning surgical skills using simulation.

PubMed

Rojas, David; Haji, Faizal; Shewaga, Rob; Kapralos, Bill; Dubrowski, Adam

2014-01-01

Interest in the measurement of cognitive load (CL) in simulation-based education has grown in recent years. In this paper we present two pilot experiments comparing the sensitivity of two reaction time based secondary task measures of CL. The results suggest that simple reaction time measures are sensitive enough to detect changes in CL experienced by novice learners in the initial stages of simulation-based surgical skills training.

Action video games do not improve the speed of information processing in simple perceptual tasks.

PubMed

van Ravenzwaaij, Don; Boekel, Wouter; Forstmann, Birte U; Ratcliff, Roger; Wagenmakers, Eric-Jan

2014-10-01

Previous research suggests that playing action video games improves performance on sensory, perceptual, and attentional tasks. For instance, Green, Pouget, and Bavelier (2010) used the diffusion model to decompose data from a motion detection task and estimate the contribution of several underlying psychological processes. Their analysis indicated that playing action video games leads to faster information processing, reduced response caution, and no difference in motor responding. Because perceptual learning is generally thought to be highly context-specific, this transfer from gaming is surprising and warrants corroborative evidence from a large-scale training study. We conducted 2 experiments in which participants practiced either an action video game or a cognitive game in 5 separate, supervised sessions. Prior to each session and following the last session, participants performed a perceptual discrimination task. In the second experiment, we included a third condition in which no video games were played at all. Behavioral data and diffusion model parameters showed similar practice effects for the action gamers, the cognitive gamers, and the nongamers and suggest that, in contrast to earlier reports, playing action video games does not improve the speed of information processing in simple perceptual tasks.

Action Video Games Do Not Improve the Speed of Information Processing in Simple Perceptual Tasks

PubMed Central

van Ravenzwaaij, Don; Boekel, Wouter; Forstmann, Birte U.; Ratcliff, Roger; Wagenmakers, Eric-Jan

2015-01-01

Previous research suggests that playing action video games improves performance on sensory, perceptual, and attentional tasks. For instance, Green, Pouget, and Bavelier (2010) used the diffusion model to decompose data from a motion detection task and estimate the contribution of several underlying psychological processes. Their analysis indicated that playing action video games leads to faster information processing, reduced response caution, and no difference in motor responding. Because perceptual learning is generally thought to be highly context-specific, this transfer from gaming is surprising and warrants corroborative evidence from a large-scale training study. We conducted 2 experiments in which participants practiced either an action video game or a cognitive game in 5 separate, supervised sessions. Prior to each session and following the last session, participants performed a perceptual discrimination task. In the second experiment, we included a third condition in which no video games were played at all. Behavioral data and diffusion model parameters showed similar practice effects for the action gamers, the cognitive gamers, and the nongamers and suggest that, in contrast to earlier reports, playing action video games does not improve the speed of information processing in simple perceptual tasks. PMID:24933517

Simple hybrid method for fine microaneurysm detection from non-dilated diabetic retinopathy retinal images.

PubMed

Sopharak, Akara; Uyyanonvara, Bunyarit; Barman, Sarah

2013-01-01

Microaneurysms detection is an important task in computer aided diagnosis of diabetic retinopathy. Microaneurysms are the first clinical sign of diabetic retinopathy, a major cause of vision loss in diabetic patients. Early microaneurysm detection can help reduce the incidence of blindness. Automatic detection of microaneurysms is still an open problem due to their tiny sizes, low contrast and also similarity with blood vessels. It is particularly very difficult to detect fine microaneurysms, especially from non-dilated pupils and that is the goal of this paper. Simple yet effective methods are used. They are coarse segmentation using mathematic morphology and fine segmentation using naive Bayes classifier. A total of 18 microaneurysms features are proposed in this paper and they are extracted for naive Bayes classifier. The detected microaneurysms are validated by comparing at pixel level with ophthalmologists' hand-drawn ground-truth. The sensitivity, specificity, precision and accuracy are 85.68, 99.99, 83.34 and 99.99%, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impaired Activation of Visual Attention Network for Motion Salience Is Accompanied by Reduced Functional Connectivity between Frontal Eye Fields and Visual Cortex in Strabismic Amblyopia

PubMed Central

Wang, Hao; Crewther, Sheila G.; Liang, Minglong; Laycock, Robin; Yu, Tao; Alexander, Bonnie; Crewther, David P.; Wang, Jian; Yin, Zhengqin

2017-01-01

Strabismic amblyopia is now acknowledged to be more than a simple loss of acuity and to involve alterations in visually driven attention, though whether this applies to both stimulus-driven and goal-directed attention has not been explored. Hence we investigated monocular threshold performance during a motion salience-driven attention task involving detection of a coherent dot motion target in one of four quadrants in adult controls and those with strabismic amblyopia. Psychophysical motion thresholds were impaired for the strabismic amblyopic eye, requiring longer inspection time and consequently slower target speed for detection compared to the fellow eye or control eyes. We compared fMRI activation and functional connectivity between four ROIs of the occipital-parieto-frontal visual attention network [primary visual cortex (V1), motion sensitive area V5, intraparietal sulcus (IPS) and frontal eye fields (FEF)], during a suprathreshold version of the motion-driven attention task, and also a simple goal-directed task, requiring voluntary saccades to targets randomly appearing along a horizontal line. Activation was compared when viewed monocularly by controls and the amblyopic and its fellow eye in strabismics. BOLD activation was weaker in IPS, FEF and V5 for both tasks when viewing through the amblyopic eye compared to viewing through the fellow eye or control participants' non-dominant eye. No difference in V1 activation was seen between the amblyopic and fellow eye, nor between the two eyes of control participants during the motion salience task, though V1 activation was significantly less through the amblyopic eye than through the fellow eye and control group non-dominant eye viewing during the voluntary saccade task. Functional correlations of ROIs within the attention network were impaired through the amblyopic eye during the motion salience task, whereas this was not the case during the voluntary saccade task. Specifically, FEF showed reduced functional connectivity with visual cortical nodes during the motion salience task through the amblyopic eye, despite suprathreshold detection performance. This suggests that the reduced ability of the amblyopic eye to activate the frontal components of the attention networks may help explain the aberrant control of visual attention and eye movements in amblyopes. PMID:28484381

Choose and choose again: appearance-reality errors, pragmatics and logical ability.

PubMed

Deák, Gedeon O; Enright, Brian

2006-05-01

In the Appearance/Reality (AR) task some 3- and 4-year-old children make perseverative errors: they choose the same word for the appearance and the function of a deceptive object. Are these errors specific to the AR task, or signs of a general question-answering problem? Preschoolers completed five tasks: AR; simple successive forced-choice question pairs (QP); flexible naming of objects (FN); working memory (WM) span; and indeterminacy detection (ID). AR errors correlated with QP errors. Insensitivity to indeterminacy predicted perseveration in both tasks. Neither WM span nor flexible naming predicted other measures. Age predicted sensitivity to indeterminacy. These findings suggest that AR tests measure a pragmatic understanding; specifically, different questions about a topic usually call for different answers. This understanding is related to the ability to detect indeterminacy of each question in a series. AR errors are unrelated to the ability to represent an object as belonging to multiple categories, to working memory span, or to inhibiting previously activated words.

Simple and efficient machine learning frameworks for identifying protein-protein interaction relevant articles and experimental methods used to study the interactions.

PubMed

Agarwal, Shashank; Liu, Feifan; Yu, Hong

2011-10-03

Protein-protein interaction (PPI) is an important biomedical phenomenon. Automatically detecting PPI-relevant articles and identifying methods that are used to study PPI are important text mining tasks. In this study, we have explored domain independent features to develop two open source machine learning frameworks. One performs binary classification to determine whether the given article is PPI relevant or not, named "Simple Classifier", and the other one maps the PPI relevant articles with corresponding interaction method nodes in a standardized PSI-MI (Proteomics Standards Initiative-Molecular Interactions) ontology, named "OntoNorm". We evaluated our system in the context of BioCreative challenge competition using the standardized data set. Our systems are amongst the top systems reported by the organizers, attaining 60.8% F1-score for identifying relevant documents, and 52.3% F1-score for mapping articles to interaction method ontology. Our results show that domain-independent machine learning frameworks can perform competitively well at the tasks of detecting PPI relevant articles and identifying the methods that were used to study the interaction in such articles. Simple Classifier is available at http://sourceforge.net/p/simpleclassify/home/ and OntoNorm at http://sourceforge.net/p/ontonorm/home/.

Measures and Interpretations of Vigilance Performance: Evidence Against the Detection Criterion

NASA Technical Reports Server (NTRS)

Balakrishnan, J. D.

1998-01-01

Operators' performance in a vigilance task is often assumed to depend on their choice of a detection criterion. When the signal rate is low this criterion is set high, causing the hit and false alarm rates to be low. With increasing time on task the criterion presumably tends to increase even further, thereby further decreasing the hit and false alarm rates. Virtually all of the empirical evidence for this simple interpretation is based on estimates of the bias measure Beta from signal detection theory. In this article, I describe a new approach to studying decision making that does not require the technical assumptions of signal detection theory. The results of this new analysis suggest that the detection criterion is never biased toward either response, even when the signal rate is low and the time on task is long. Two modifications of the signal detection theory framework are considered to account for this seemingly paradoxical result. The first assumes that the signal rate affects the relative sizes of the variances of the information distributions; the second assumes that the signal rate affects the logic of the operator's stopping rule. Actual or potential applications of this research include the improved training and performance assessment of operators in areas such as product quality control, air traffic control, and medical and clinical diagnosis.

Assessing segmentation processes by click detection: online measure of statistical learning, or simple interference?

PubMed

Franco, Ana; Gaillard, Vinciane; Cleeremans, Axel; Destrebecqz, Arnaud

2015-12-01

Statistical learning can be used to extract the words from continuous speech. Gómez, Bion, and Mehler (Language and Cognitive Processes, 26, 212-223, 2011) proposed an online measure of statistical learning: They superimposed auditory clicks on a continuous artificial speech stream made up of a random succession of trisyllabic nonwords. Participants were instructed to detect these clicks, which could be located either within or between words. The results showed that, over the length of exposure, reaction times (RTs) increased more for within-word than for between-word clicks. This result has been accounted for by means of statistical learning of the between-word boundaries. However, even though statistical learning occurs without an intention to learn, it nevertheless requires attentional resources. Therefore, this process could be affected by a concurrent task such as click detection. In the present study, we evaluated the extent to which the click detection task indeed reflects successful statistical learning. Our results suggest that the emergence of RT differences between within- and between-word click detection is neither systematic nor related to the successful segmentation of the artificial language. Therefore, instead of being an online measure of learning, the click detection task seems to interfere with the extraction of statistical regularities.

Attention to baseline: does orienting visuospatial attention really facilitate target detection?

PubMed

Albares, Marion; Criaud, Marion; Wardak, Claire; Nguyen, Song Chi Trung; Ben Hamed, Suliann; Boulinguez, Philippe

2011-08-01

Standard protocols testing the orientation of visuospatial attention usually present spatial cues before targets and compare valid-cue trials with invalid-cue trials. The valid/invalid contrast results in a relative behavioral or physiological difference that is generally interpreted as a benefit of attention orientation. However, growing evidence suggests that inhibitory control of response is closely involved in this kind of protocol that requires the subjects to withhold automatic responses to cues, probably biasing behavioral and physiological baselines. Here, we used two experiments to disentangle the inhibitory control of automatic responses from orienting of visuospatial attention in a saccadic reaction time task in humans, a variant of the classical cue-target detection task and a sustained visuospatial attentional task. Surprisingly, when referring to a simple target detection task in which there is no need to refrain from reacting to avoid inappropriate responses, we found no consistent evidence of facilitation of target detection at the attended location. Instead, we observed a cost at the unattended location. Departing from the classical view, our results suggest that reaction time measures of visuospatial attention probably relie on the attenuation of elementary processes involved in visual target detection and saccade initiation away from the attended location rather than on facilitation at the attended location. This highlights the need to use proper control conditions in experimental designs to disambiguate relative from absolute cueing benefits on target detection reaction times, both in psychophysical and neurophysiological studies.

Simple Predictions Fueled by Capacity Limitations: When Are They Successful?

ERIC Educational Resources Information Center

Gaissmaier, Wolfgang; Schooler, Lael J.; Rieskamp, Jorg

2006-01-01

Counterintuitively, Y. Kareev, I. Lieberman, and M. Lev (1997) found that a lower short-term memory capacity benefits performance on a correlation detection task. They assumed that people with low short-term memory capacity (low spans) perceived the correlations as more extreme because they relied on smaller samples, which are known to exaggerate…

Inter-cellular spike coincidences in visual detection tasks

NASA Astrophysics Data System (ADS)

Bauer, Roman; Heinze, Sabine

2002-06-01

Synchronized spike activity is discussed as a possible representational code for object integration and as a neuronal basis of attention, perception and awareness. As a byproduct of experiments in which monkeys were trained to detect simple figures composed of single Gabor patches in a noisy background of similar elements, we found in special cases increased spike synchrony above chance level specifically related to figure detection. The long latency of this effect is difficult to interpret. It may be a sign of the cognitive state of an animal when it perceives the figure.

Task-oriented quality assessment and adaptation in real-time mission critical video streaming applications

NASA Astrophysics Data System (ADS)

Nightingale, James; Wang, Qi; Grecos, Christos

2015-02-01

In recent years video traffic has become the dominant application on the Internet with global year-on-year increases in video-oriented consumer services. Driven by improved bandwidth in both mobile and fixed networks, steadily reducing hardware costs and the development of new technologies, many existing and new classes of commercial and industrial video applications are now being upgraded or emerging. Some of the use cases for these applications include areas such as public and private security monitoring for loss prevention or intruder detection, industrial process monitoring and critical infrastructure monitoring. The use of video is becoming commonplace in defence, security, commercial, industrial, educational and health contexts. Towards optimal performances, the design or optimisation in each of these applications should be context aware and task oriented with the characteristics of the video stream (frame rate, spatial resolution, bandwidth etc.) chosen to match the use case requirements. For example, in the security domain, a task-oriented consideration may be that higher resolution video would be required to identify an intruder than to simply detect his presence. Whilst in the same case, contextual factors such as the requirement to transmit over a resource-limited wireless link, may impose constraints on the selection of optimum task-oriented parameters. This paper presents a novel, conceptually simple and easily implemented method of assessing video quality relative to its suitability for a particular task and dynamically adapting videos streams during transmission to ensure that the task can be successfully completed. Firstly we defined two principle classes of tasks: recognition tasks and event detection tasks. These task classes are further subdivided into a set of task-related profiles, each of which is associated with a set of taskoriented attributes (minimum spatial resolution, minimum frame rate etc.). For example, in the detection class, profiles for intruder detection will require different temporal characteristics (frame rate) from those used for detection of high motion objects such as vehicles or aircrafts. We also define a set of contextual attributes that are associated with each instance of a running application that include resource constraints imposed by the transmission system employed and the hardware platforms used as source and destination of the video stream. Empirical results are presented and analysed to demonstrate the advantages of the proposed schemes.

A new multi-spectral feature level image fusion method for human interpretation

NASA Astrophysics Data System (ADS)

Leviner, Marom; Maltz, Masha

2009-03-01

Various different methods to perform multi-spectral image fusion have been suggested, mostly on the pixel level. However, the jury is still out on the benefits of a fused image compared to its source images. We present here a new multi-spectral image fusion method, multi-spectral segmentation fusion (MSSF), which uses a feature level processing paradigm. To test our method, we compared human observer performance in a three-task experiment using MSSF against two established methods: averaging and principle components analysis (PCA), and against its two source bands, visible and infrared. The three tasks that we studied were: (1) simple target detection, (2) spatial orientation, and (3) camouflaged target detection. MSSF proved superior to the other fusion methods in all three tests; MSSF also outperformed the source images in the spatial orientation and camouflaged target detection tasks. Based on these findings, current speculation about the circumstances in which multi-spectral image fusion in general and specific fusion methods in particular would be superior to using the original image sources can be further addressed.

COMP Superscalar, an interoperable programming framework

NASA Astrophysics Data System (ADS)

Badia, Rosa M.; Conejero, Javier; Diaz, Carlos; Ejarque, Jorge; Lezzi, Daniele; Lordan, Francesc; Ramon-Cortes, Cristian; Sirvent, Raul

2015-12-01

COMPSs is a programming framework that aims to facilitate the parallelization of existing applications written in Java, C/C++ and Python scripts. For that purpose, it offers a simple programming model based on sequential development in which the user is mainly responsible for (i) identifying the functions to be executed as asynchronous parallel tasks and (ii) annotating them with annotations or standard Python decorators. A runtime system is in charge of exploiting the inherent concurrency of the code, automatically detecting and enforcing the data dependencies between tasks and spawning these tasks to the available resources, which can be nodes in a cluster, clouds or grids. In cloud environments, COMPSs provides scalability and elasticity features allowing the dynamic provision of resources.

A fuzzy clustering algorithm to detect planar and quadric shapes

NASA Technical Reports Server (NTRS)

Krishnapuram, Raghu; Frigui, Hichem; Nasraoui, Olfa

1992-01-01

In this paper, we introduce a new fuzzy clustering algorithm to detect an unknown number of planar and quadric shapes in noisy data. The proposed algorithm is computationally and implementationally simple, and it overcomes many of the drawbacks of the existing algorithms that have been proposed for similar tasks. Since the clustering is performed in the original image space, and since no features need to be computed, this approach is particularly suited for sparse data. The algorithm may also be used in pattern recognition applications.

Dimension- and space-based intertrial effects in visual pop-out search: modulation by task demands for focal-attentional processing.

PubMed

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

2009-03-01

Two experiments compared reaction times (RTs) in visual search for singleton feature targets defined, variably across trials, in either the color or the orientation dimension. Experiment 1 required observers to simply discern target presence versus absence (simple-detection task); Experiment 2 required them to respond to a detection-irrelevant form attribute of the target (compound-search task). Experiment 1 revealed a marked dimensional intertrial effect of 34 ms for an target defined in a changed versus a repeated dimension, and an intertrial target distance effect, with an 4-ms increase in RTs (per unit of distance) as the separation of the current relative to the preceding target increased. Conversely, in Experiment 2, the dimension change effect was markedly reduced (11 ms), while the intertrial target distance effect was markedly increased (11 ms per unit of distance). The results suggest that dimension change/repetition effects are modulated by the amount of attentional focusing required by the task, with space-based attention altering the integration of dimension-specific feature contrast signals at the level of the overall-saliency map.

Creating Simple Windchill Admin Tools Using Info*Engine

NASA Technical Reports Server (NTRS)

Jones, Corey; Kapatos, Dennis; Skradski, Cory

2012-01-01

Being a Windchill administrator often requires performing simple yet repetitive tasks on large sets of objects. These can include renaming, deleting, checking in, undoing checkout, and much more. This is especially true during a migration. Fortunately, PTC has provided a simple way to dynamically interact with Windchill using Info*Engine. This presentation will describe how to create simple Info*Engine tasks capable of saving Windchill 10.0 administrators hours of tedious work. It will also show how these tasks can be combined and displayed on a simple JSP page that acts as a "Windchill Administrator Dashboard/Toolbox". The attendee will learn some valuable tasks Info*Engine capable of performing. The attendee will gain a basic understanding of how to perform and implement Info*Engine tasks. The attendee will learn what's involved in creating a JSP page that displays Info*Engine tasks

A comparison of the effects of a secondary task and lorazepam on cognitive performance.

PubMed

File, S E

1992-01-01

In order to test whether the lorazepam-induced impairments in a variety of cognitive tasks were similar to those of divided attention, the effects of lorazepam (2.5 mg) in healthy volunteers were compared with those requiring subjects to perform an additional task (detecting silences superimposed onto classical music). Neither treatment impaired implicit memory or judgements of frequency. Both treatments impaired performance in tests of speed, lorazepam having the greatest effect on number cancellation and the additional task having the greatest effect on simple reaction time. Both treatments impaired performance in a coding task, in a test of explicit episodic memory and in judgements of recency (indicating impaired coding of contextual information). Lorazepam significantly reduced performance in a word completion task, but this was unimpaired in the group performing the additional task. In general, the pattern of results suggests that there are similarities between the effects of divided attention and lorazepam treatment, and that lorazepam-induced cognitive impairments are not restricted to explicit tests of episodic memory.

Shape detection of Gaborized outline versions of everyday objects

PubMed Central

Sassi, Michaël; Machilsen, Bart; Wagemans, Johan

2012-01-01

We previously tested the identifiability of six versions of Gaborized outlines of everyday objects, differing in the orientations assigned to elements inside and outside the outline. We found significant differences in identifiability between the versions, and related a number of stimulus metrics to identifiability [Sassi, M., Vancleef, K., Machilsen, B., Panis, S., & Wagemans, J. (2010). Identification of everyday objects on the basis of Gaborized outline versions. i-Perception, 1(3), 121–142]. In this study, after retesting the identifiability of new variants of three of the stimulus versions, we tested their robustness to local orientation jitter in a detection experiment. In general, our results replicated the key findings from the previous study, and allowed us to substantiate our earlier interpretations of the effects of our stimulus metrics and of the performance differences between the different stimulus versions. The results of the detection task revealed a different ranking order of stimulus versions than the identification task. By examining the parallels and differences between the effects of our stimulus metrics in the two tasks, we found evidence for a trade-off between shape detectability and identifiability. The generally simple and smooth shapes that yield the strongest contour integration and most robust detectability tend to lack the distinguishing features necessary for clear-cut identification. Conversely, contours that do contain such identifying features tend to be inherently more complex and, therefore, yield weaker integration and less robust detectability. PMID:23483752

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.

Classification image analysis: estimation and statistical inference for two-alternative forced-choice experiments

NASA Technical Reports Server (NTRS)

Abbey, Craig K.; Eckstein, Miguel P.

2002-01-01

We consider estimation and statistical hypothesis testing on classification images obtained from the two-alternative forced-choice experimental paradigm. We begin with a probabilistic model of task performance for simple forced-choice detection and discrimination tasks. Particular attention is paid to general linear filter models because these models lead to a direct interpretation of the classification image as an estimate of the filter weights. We then describe an estimation procedure for obtaining classification images from observer data. A number of statistical tests are presented for testing various hypotheses from classification images based on some more compact set of features derived from them. As an example of how the methods we describe can be used, we present a case study investigating detection of a Gaussian bump profile.

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

Examining the effects of an eco-driving message on driver distraction.

PubMed

Rouzikhah, Hossein; King, Mark; Rakotonirainy, Andry

2013-01-01

This paper examines the effects of an eco-driving message on driver distraction. Two in-vehicle distracter tasks were compared with an eco-driving task and a baseline task in an advanced driving simulator. N=22 subjects were asked to perform an eco-driving, CD changing, and a navigation task while engaged in critical manoeuvres during which they were expected to respond to a peripheral detection task (PDT) with total duration of 3.5h. The study involved two sessions over two consecutive days. The results show that drivers' mental workloads are significantly higher during navigation and CD changing tasks in comparison to the two other scenarios. However, eco-driving mental workload is still marginally significant (p∼.05) across different manoeuvres. Similarly, event detection tasks show that drivers miss significantly more events in the navigation and CD changing scenarios in comparison to both the baseline and eco-driving scenario. Analysis of the practice effect shows that drivers' baseline scenario and navigation scenario exhibit significantly less demand on the second day. Drivers also can detect significantly more events on the second day for all scenarios. The authors conclude that even reading a simple message while driving could potentially lead to missing an important event, especially when executing critical manoeuvres. However, there is some evidence of a practice effect which suggests that future research should focus on performance with habitual rather than novel tasks. It is recommended that sending text as an eco-driving message analogous to the study circumstances should not be delivered to drivers on-line when vehicle is in motion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Japanese professional nurses spend unnecessarily long time doing nursing assistants' tasks.

PubMed

Kudo, Yasushi; Yoshimura, Emiko; Shahzad, Machiko Taruzuka; Shibuya, Akitaka; Aizawa, Yoshiharu

2012-09-01

In environments in which professional nurses do simple tasks, e.g., laundry, cleaning, and waste disposal, they cannot concentrate on technical jobs by utilizing their expertise to its fullest benefit. Particularly, in Japan, the nursing shortage is a serious problem. If professional nurses take their time to do any of these simple tasks, the tasks should be preferentially allocated to nursing assistants. Because there has been no descriptive study to investigate the amount of time Japanese professional nurses spent doing such simple tasks during their working time, their actual conditions remain unclear. Professional nurses recorded their total working time and the time they spent doing such simple tasks during the week of the survey period. The time an individual respondent spent doing one or more simple tasks during that week was summed up, as was their working time. Subsequently, the percentage of the summed time he or she spent doing any of those tasks in his or her summed working time was calculated. A total of 1,086 respondents in 19 hospitals that had 87 to 376 beds were analyzed (response rate: 53.3%). The average time (SD) that respondents spent doing those simple tasks and their total working time were 2.24 (3.35) hours and 37.48 (10.88) hours, respectively. The average percentage (SD) of the time they spent doing the simple tasks in their working time was 6.00% (8.39). Hospital administrators must decrease this percentage. Proper working environments in which professional nurses can concentrate more on their technical jobs must be created.

Sequencing sit-to-stand and upright posture for mobility limitation assessment: determination of the timing of the task phases from force platform data.

PubMed

Mazzà, Claudia; Zok, Mounir; Della Croce, Ugo

2005-06-01

The identification of quantitative tools to assess an individual's mobility limitation is a complex and challenging task. Several motor tasks have been designated as potential indicators of mobility limitation. In this study, a multiple motor task obtained by sequencing sit-to-stand and upright posture was used. Algorithms based on data obtained exclusively from a single force platform were developed to detect the timing of the motor task phases (sit-to-stand, preparation to the upright posture and upright posture). To test these algorithms, an experimental protocol inducing predictable changes in the acquired signals was designed. Twenty-two young, able-bodied subjects performed the task in four different conditions: self-selected natural and high speed with feet kept together, and self-selected natural and high speed with feet pelvis-width apart. The proposed algorithms effectively detected the timing of the task phases, the duration of which was sensitive to the four different experimental conditions. As expected, the duration of the sit-to-stand was sensitive to the speed of the task and not to the foot position, while the duration of the preparation to the upright posture was sensitive to foot position but not to speed. In addition to providing a simple and effective description of the execution of the motor task, the correct timing of the studied multiple task could facilitate the accurate determination of variables descriptive of the single isolated phases, allowing for a more thorough description of the motor task and therefore could contribute to the development of effective quantitative functional evaluation tests.

Psychopathic traits associated with abnormal hemodynamic activity in salience and default mode networks during auditory oddball task.

PubMed

Anderson, Nathaniel E; Maurer, J Michael; Steele, Vaughn R; Kiehl, Kent A

2018-06-01

Psychopathy is a personality disorder accompanied by abnormalities in emotional processing and attention. Recent theoretical applications of network-based models of cognition have been used to explain the diverse range of abnormalities apparent in psychopathy. Still, the physiological basis for these abnormalities is not well understood. A significant body of work has examined psychopathy-related abnormalities in simple attention-based tasks, but these studies have largely been performed using electrocortical measures, such as event-related potentials (ERPs), and they often have been carried out among individuals with low levels of psychopathic traits. In this study, we examined neural activity during an auditory oddball task using functional magnetic resonance imaging (fMRI) during a simple auditory target detection (oddball) task among 168 incarcerated adult males, with psychopathic traits assessed via the Hare Psychopathy Checklist-Revised (PCL-R). Event-related contrasts demonstrated that the largest psychopathy-related effects were apparent between the frequent standard stimulus condition and a task-off, implicit baseline. Negative correlations with interpersonal-affective dimensions (Factor 1) of the PCL-R were apparent in regions comprising default mode and salience networks. These findings support models of psychopathy describing impaired integration across functional networks. They additionally corroborate reports which have implicated failures of efficient transition between default mode and task-positive networks. Finally, they demonstrate a neurophysiological basis for abnormal mobilization of attention and reduced engagement with stimuli that have little motivational significance among those with high psychopathic traits.

Attentional bias induced by solving simple and complex addition and subtraction problems.

PubMed

Masson, Nicolas; Pesenti, Mauro

2014-01-01

The processing of numbers has been shown to induce shifts of spatial attention in simple probe detection tasks, with small numbers orienting attention to the left and large numbers to the right side of space. Recently, the investigation of this spatial-numerical association has been extended to mental arithmetic with the hypothesis that solving addition or subtraction problems may induce attentional displacements (to the right and to the left, respectively) along a mental number line onto which the magnitude of the numbers would range from left to right, from small to large numbers. Here we investigated such attentional shifts using a target detection task primed by arithmetic problems in healthy participants. The constituents of the addition and subtraction problems (first operand; operator; second operand) were flashed sequentially in the centre of a screen, then followed by a target on the left or the right side of the screen, which the participants had to detect. This paradigm was employed with arithmetic facts (Experiment 1) and with more complex arithmetic problems (Experiment 2) in order to assess the effects of the operation, the magnitude of the operands, the magnitude of the results, and the presence or absence of a requirement for the participants to carry or borrow numbers. The results showed that arithmetic operations induce some spatial shifts of attention, possibly through a semantic link between the operation and space.

Sensory dominance and multisensory integration as screening tools in aging.

PubMed

Murray, Micah M; Eardley, Alison F; Edginton, Trudi; Oyekan, Rebecca; Smyth, Emily; Matusz, Pawel J

2018-06-11

Multisensory information typically confers neural and behavioural advantages over unisensory information. We used a simple audio-visual detection task to compare healthy young (HY), healthy older (HO) and mild-cognitive impairment (MCI) individuals. Neuropsychological tests assessed individuals' learning and memory impairments. First, we provide much-needed clarification regarding the presence of enhanced multisensory benefits in both healthily and abnormally aging individuals. The pattern of sensory dominance shifted with healthy and abnormal aging to favour a propensity of auditory-dominant behaviour (i.e., detecting sounds faster than flashes). Notably, multisensory benefits were larger only in healthy older than younger individuals who were also visually-dominant. Second, we demonstrate that the multisensory detection task offers benefits as a time- and resource-economic MCI screening tool. Receiver operating characteristic (ROC) analysis demonstrated that MCI diagnosis could be reliably achieved based on the combination of indices of multisensory integration together with indices of sensory dominance. Our findings showcase the importance of sensory profiles in determining multisensory benefits in healthy and abnormal aging. Crucially, our findings open an exciting possibility for multisensory detection tasks to be used as a cost-effective screening tool. These findings clarify relationships between multisensory and memory functions in aging, while offering new avenues for improved dementia diagnostics.

Emotion Evaluation and Response Slowing in a Non-Human Primate: New Directions for Cognitive Bias Measures of Animal Emotion?

PubMed Central

Bethell, Emily J.; Holmes, Amanda; MacLarnon, Ann; Semple, Stuart

2016-01-01

The cognitive bias model of animal welfare assessment is informed by studies with humans demonstrating that the interaction between emotion and cognition can be detected using laboratory tasks. A limitation of cognitive bias tasks is the amount of training required by animals prior to testing. A potential solution is to use biologically relevant stimuli that trigger innate emotional responses. Here; we develop a new method to assess emotion in rhesus macaques; informed by paradigms used with humans: emotional Stroop; visual cueing and; in particular; response slowing. In humans; performance on a simple cognitive task can become impaired when emotional distractor content is displayed. Importantly; responses become slower in anxious individuals in the presence of mild threat; a pattern not seen in non-anxious individuals; who are able to effectively process and disengage from the distractor. Here; we present a proof-of-concept study; demonstrating that rhesus macaques show slowing of responses in a simple touch-screen task when emotional content is introduced; but only when they had recently experienced a presumably stressful veterinary inspection. Our results indicate the presence of a subtle “cognitive freeze” response; the measurement of which may provide a means of identifying negative shifts in emotion in animals. PMID:26761035

The effect of a graphical interpretation of a statistic trend indicator (Trigg's Tracking Variable) on the detection of simulated changes.

PubMed

Kennedy, R R; Merry, A F

2011-09-01

Anaesthesia involves processing large amounts of information over time. One task of the anaesthetist is to detect substantive changes in physiological variables promptly and reliably. It has been previously demonstrated that a graphical trend display of historical data leads to more rapid detection of such changes. We examined the effect of a graphical indication of the magnitude of Trigg's Tracking Variable, a simple statistically based trend detection algorithm, on the accuracy and latency of the detection of changes in a micro-simulation. Ten anaesthetists each viewed 20 simulations with four variables displayed as the current value with a simple graphical trend display. Values for these variables were generated by a computer model, and updated every second; after a period of stability a change occurred to a new random value at least 10 units from baseline. In 50% of the simulations an indication of the rate of change was given by a five level graphical representation of the value of Trigg's Tracking Variable. Participants were asked to indicate when they thought a change was occurring. Changes were detected 10.9% faster with the trend indicator present (mean 13.1 [SD 3.1] cycles vs 14.6 [SD 3.4] cycles, 95% confidence interval 0.4 to 2.5 cycles, P = 0.013. There was no difference in accuracy of detection (median with trend detection 97% [interquartile range 95 to 100%], without trend detection 100% [98 to 100%]), P = 0.8. We conclude that simple statistical trend detection may speed detection of changes during routine anaesthesia, even when a graphical trend display is present.

From Brown-Peterson to continual distractor via operation span: A SIMPLE account of complex span.

PubMed

Neath, Ian; VanWormer, Lisa A; Bireta, Tamra J; Surprenant, Aimée M

2014-09-01

Three memory tasks-Brown-Peterson, complex span, and continual distractor-all alternate presentation of a to-be-remembered item and a distractor activity, but each task is associated with a different memory system, short-term memory, working memory, and long-term memory, respectively. SIMPLE, a relative local distinctiveness model, has previously been fit to data from both the Brown-Peterson and continual distractor tasks; here we use the same version of the model to fit data from a complex span task. Despite the many differences between the tasks, including unpredictable list length, SIMPLE fit the data well. Because SIMPLE posits a single memory system, these results constitute yet another demonstration that performance on tasks originally thought to tap different memory systems can be explained without invoking multiple memory systems.

A Method for Automated Detection of Usability Problems from Client User Interface Events

PubMed Central

Saadawi, Gilan M.; Legowski, Elizabeth; Medvedeva, Olga; Chavan, Girish; Crowley, Rebecca S.

2005-01-01

Think-aloud usability analysis provides extremely useful data but is very time-consuming and expensive to perform because of the extensive manual video analysis that is required. We describe a simple method for automated detection of usability problems from client user interface events for a developing medical intelligent tutoring system. The method incorporates (1) an agent-based method for communication that funnels all interface events and system responses to a centralized database, (2) a simple schema for representing interface events and higher order subgoals, and (3) an algorithm that reproduces the criteria used for manual coding of usability problems. A correction factor was empirically determining to account for the slower task performance of users when thinking aloud. We tested the validity of the method by simultaneously identifying usability problems using TAU and manually computing them from stored interface event data using the proposed algorithm. All usability problems that did not rely on verbal utterances were detectable with the proposed method. PMID:16779121

Executive working memory load induces inattentional blindness.

PubMed

Fougnie, Daryl; Marois, René

2007-02-01

When attention is engaged in a task, unexpected events in the visual scene may go undetected, a phenomenon known as inattentional blindness (IB). At what stage of information processing must attention be engaged for IB to occur? Although manipulations that tax visuospatial attention can induce IB, the evidence is more equivocal for tasks that engage attention at late, central stages of information processing. Here, we tested whether IB can be specifically induced by central executive processes. An unexpected visual stimulus was presented during the retention interval of a working memory task that involved either simply maintaining verbal material or rearranging the material into alphabetical order. The unexpected stimulus was more likely to be missed during manipulation than during simple maintenance of the verbal information. Thus, the engagement of executive processes impairs the ability to detect unexpected, task-irrelevant stimuli, suggesting that IB can result from central, amodal stages of processing.

Simple and Complex Memory Spans and Their Relation to Fluid Abilities: Evidence from List-Length Effects

ERIC Educational Resources Information Center

Unsworth, Nash; Engle, Randall W.

2006-01-01

Complex (working memory) span tasks have generally shown larger and more consistent correlations with higher-order cognition than have simple (or short-term memory) span tasks. The relation between verbal complex and simple verbal span tasks to fluid abilities as a function of list-length was examined. The results suggest that the simple…

Using pattern recognition to automatically localize reflection hyperbolas in data from ground penetrating radar

NASA Astrophysics Data System (ADS)

Maas, Christian; Schmalzl, Jörg

2013-08-01

Ground Penetrating Radar (GPR) is used for the localization of supply lines, land mines, pipes and many other buried objects. These objects can be recognized in the recorded data as reflection hyperbolas with a typical shape depending on depth and material of the object and the surrounding material. To obtain the parameters, the shape of the hyperbola has to be fitted. In the last years several methods were developed to automate this task during post-processing. In this paper we show another approach for the automated localization of reflection hyperbolas in GPR data by solving a pattern recognition problem in grayscale images. In contrast to other methods our detection program is also able to immediately mark potential objects in real-time. For this task we use a version of the Viola-Jones learning algorithm, which is part of the open source library "OpenCV". This algorithm was initially developed for face recognition, but can be adapted to any other simple shape. In our program it is used to narrow down the location of reflection hyperbolas to certain areas in the GPR data. In order to extract the exact location and the velocity of the hyperbolas we apply a simple Hough Transform for hyperbolas. Because the Viola-Jones Algorithm reduces the input for the computational expensive Hough Transform dramatically the detection system can also be implemented on normal field computers, so on-site application is possible. The developed detection system shows promising results and detection rates in unprocessed radargrams. In order to improve the detection results and apply the program to noisy radar images more data of different GPR systems as input for the learning algorithm is necessary.

Caffeine enhances real-world language processing: evidence from a proofreading task.

PubMed

Brunyé, Tad T; Mahoney, Caroline R; Rapp, David N; Ditman, Tali; Taylor, Holly A

2012-03-01

Caffeine has become the most prevalently consumed psychostimulant in the world, but its influences on daily real-world functioning are relatively unknown. The present work investigated the effects of caffeine (0 mg, 100 mg, 200 mg, 400 mg) on a commonplace language task that required readers to identify and correct 4 error types in extended discourse: simple local errors (misspelling 1- to 2-syllable words), complex local errors (misspelling 3- to 5-syllable words), simple global errors (incorrect homophones), and complex global errors (incorrect subject-verb agreement and verb tense). In 2 placebo-controlled, double-blind studies using repeated-measures designs, we found higher detection and repair rates for complex global errors, asymptoting at 200 mg in low consumers (Experiment 1) and peaking at 400 mg in high consumers (Experiment 2). In both cases, covariate analyses demonstrated that arousal state mediated the relationship between caffeine consumption and the detection and repair of complex global errors. Detection and repair rates for the other 3 error types were not affected by caffeine consumption. Taken together, we demonstrate that caffeine has differential effects on error detection and repair as a function of dose and error type, and this relationship is closely tied to caffeine's effects on subjective arousal state. These results support the notion that central nervous system stimulants may enhance global processing of language-based materials and suggest that such effects may originate in caffeine-related right hemisphere brain processes. Implications for understanding the relationships between caffeine consumption and real-world cognitive functioning are discussed. PsycINFO Database Record (c) 2012 APA, all rights reserved.

A resource for assessing information processing in the developing brain using EEG and eye tracking

PubMed Central

Langer, Nicolas; Ho, Erica J.; Alexander, Lindsay M.; Xu, Helen Y.; Jozanovic, Renee K.; Henin, Simon; Petroni, Agustin; Cohen, Samantha; Marcelle, Enitan T.; Parra, Lucas C.; Milham, Michael P.; Kelly, Simon P.

2017-01-01

We present a dataset combining electrophysiology and eye tracking intended as a resource for the investigation of information processing in the developing brain. The dataset includes high-density task-based and task-free EEG, eye tracking, and cognitive and behavioral data collected from 126 individuals (ages: 6–44). The task battery spans both the simple/complex and passive/active dimensions to cover a range of approaches prevalent in modern cognitive neuroscience. The active task paradigms facilitate principled deconstruction of core components of task performance in the developing brain, whereas the passive paradigms permit the examination of intrinsic functional network activity during varying amounts of external stimulation. Alongside these neurophysiological data, we include an abbreviated cognitive test battery and questionnaire-based measures of psychiatric functioning. We hope that this dataset will lead to the development of novel assays of neural processes fundamental to information processing, which can be used to index healthy brain development as well as detect pathologic processes. PMID:28398357

A resource for assessing information processing in the developing brain using EEG and eye tracking.

PubMed

Langer, Nicolas; Ho, Erica J; Alexander, Lindsay M; Xu, Helen Y; Jozanovic, Renee K; Henin, Simon; Petroni, Agustin; Cohen, Samantha; Marcelle, Enitan T; Parra, Lucas C; Milham, Michael P; Kelly, Simon P

2017-04-11

We present a dataset combining electrophysiology and eye tracking intended as a resource for the investigation of information processing in the developing brain. The dataset includes high-density task-based and task-free EEG, eye tracking, and cognitive and behavioral data collected from 126 individuals (ages: 6-44). The task battery spans both the simple/complex and passive/active dimensions to cover a range of approaches prevalent in modern cognitive neuroscience. The active task paradigms facilitate principled deconstruction of core components of task performance in the developing brain, whereas the passive paradigms permit the examination of intrinsic functional network activity during varying amounts of external stimulation. Alongside these neurophysiological data, we include an abbreviated cognitive test battery and questionnaire-based measures of psychiatric functioning. We hope that this dataset will lead to the development of novel assays of neural processes fundamental to information processing, which can be used to index healthy brain development as well as detect pathologic processes.

Stimulus-dependent deliberation process leading to a specific motor action demonstrated via a multi-channel EEG analysis

PubMed Central

Henz, Sonja; Kutz, Dieter F.; Werner, Jana; Hürster, Walter; Kolb, Florian P.; Nida-Ruemelin, Julian

2015-01-01

The aim of the study was to determine whether a deliberative process, leading to a motor action, is detectable in high density EEG recordings. Subjects were required to press one of two buttons. In a simple motor task the subject knew which button to press, whilst in a color-word Stroop task subjects had to press the right button with the right index finger when meaning and color coincided, or the left button with the left index finger when meaning and color were disparate. EEG recordings obtained during the simple motor task showed a sequence of positive (P) and negative (N) cortical potentials (P1-N1-P2) which are assumed to be related to the processing of the movement. The sequence of cortical potentials was similar in EEG recordings of subjects having to deliberate over how to respond, but the above sequence (P1-N1-P2) was preceded by slowly increasing negativity (N0), with N0 being assumed to represent the end of the deliberation process. Our data suggest the existence of neurophysiological correlates of deliberative processes. PMID:26190987

Contribution of strategy use to performance on complex and simple span tasks.

PubMed

Bailey, Heather; Dunlosky, John; Kane, Michael J

2011-04-01

Simple and complex span tasks are widely thought to measure related but separable memory constructs. Recently, however, research has demonstrated that simple and complex span tasks may tap, in part, the same construct because both similarly predict performance on measures of fluid intelligence (Gf) when the number of items retrieved from secondary memory (SM) is equated (Unsworth & Engle, Journal of Memory and Language 54:68-80 2006). Two studies (n = 105 and n = 152) evaluated whether retrieval from SM is influenced by individual differences in the use of encoding strategies during span tasks. Results demonstrated that, after equating the number of items retrieved from SM, simple and complex span performance similarly predicted Gf performance, but rates of effective strategy use did not mediate the span-Gf relationships. Moreover, at the level of individual differences, effective strategy use was more highly related to complex span performance than to simple span performance. Thus, even though individual differences in effective strategy use influenced span performance on trials that required retrieval from SM, strategic behavior at encoding cannot account for the similarities between simple and complex span tasks.

Casual Video Games as Training Tools for Attentional Processes in Everyday Life.

PubMed

Stroud, Michael J; Whitbourne, Susan Krauss

2015-11-01

Three experiments examined the attentional components of the popular match-3 casual video game, Bejeweled Blitz (BJB). Attentionally demanding, BJB is highly popular among adults, particularly those in middle and later adulthood. In experiment 1, 54 older adults (Mage = 70.57) and 33 younger adults (Mage = 19.82) played 20 rounds of BJB, and completed online tasks measuring reaction time, simple visual search, and conjunction visual search. Prior experience significantly predicted BJB scores for younger adults, but for older adults, both prior experience and simple visual search task scores predicted BJB performance. Experiment 2 tested whether BJB practice alone would result in a carryover benefit to a visual search task in a sample of 58 young adults (Mage = 19.57) who completed 0, 10, or 30 rounds of BJB followed by a BJB-like visual search task with targets present or absent. Reaction times were significantly faster for participants who completed 30 but not 10 rounds of BJB compared with the search task only. This benefit was evident when targets were both present and absent, suggesting that playing BJB improves not only target detection, but also the ability to quit search effectively. Experiment 3 tested whether the attentional benefit in experiment 2 would apply to non-BJB stimuli. The results revealed a similar numerical but not significant trend. Taken together, the findings suggest there are benefits of casual video game playing to attention and relevant everyday skills, and that these games may have potential value as training tools.

A NEW LOOK AT THE EFFECTS OF ANXIETY AND STRESS ON THE PERFORMANCE OF COMPLEX INTELLECTUAL TASKS, STUDY II. SCHOOL ANXIETY AND COGNITIVE FUNCTIONING--EXPLORATORY STUDIES.

ERIC Educational Resources Information Center

DUNN, JAMES A.

THE EFFECTS OF TEST ANXIETY AND TEST STRESS ON THE PERFORMANCE OF TWO DIFFERENT INTELLECTUAL TASKS WERE STUDIED. IT WAS HYPOTHESIZED THAT THE DESCRIPTIVE EFFECTS OF ANXIETY WOULD BE GREATER FOR DIFFICULT BUT SIMPLE TASKS THAN FOR COMPLEX BUT EASY TASKS, AND THAT SITUATIONAL STRESS WOULD BE MORE DISRUPTIVE FOR COMPLEX TASKS THAN FOR SIMPLE TASKS. A…

Finding a face in the crowd: testing the anger superiority effect in Asperger Syndrome.

PubMed

Ashwin, Chris; Wheelwright, Sally; Baron-Cohen, Simon

2006-06-01

Social threat captures attention and is processed rapidly and efficiently, with many lines of research showing involvement of the amygdala. Visual search paradigms looking at social threat have shown angry faces 'pop-out' in a crowd, compared to happy faces. Autism and Asperger Syndrome (AS) are neurodevelopmental conditions characterised by social deficits, abnormal face processing, and amygdala dysfunction. We tested adults with high-functioning autism (HFA) and AS using a facial visual search paradigm with schematic neutral and emotional faces. We found, contrary to predictions, that people with HFA/AS performed similarly to controls in many conditions. However, the effect was reduced in the HFA/AS group when using widely varying crowd sizes and when faces were inverted, suggesting a difference in face-processing style may be evident even with simple schematic faces. We conclude there are intact threat detection mechanisms in AS, under simple and predictable conditions, but that like other face-perception tasks, the visual search of threat faces task reveals atypical face-processing in HFA/AS.

Mental chronometry with simple linear regression.

PubMed

Chen, J Y

1997-10-01

Typically, mental chronometry is performed by means of introducing an independent variable postulated to affect selectively some stage of a presumed multistage process. However, the effect could be a global one that spreads proportionally over all stages of the process. Currently, there is no method to test this possibility although simple linear regression might serve the purpose. In the present study, the regression approach was tested with tasks (memory scanning and mental rotation) that involved a selective effect and with a task (word superiority effect) that involved a global effect, by the dominant theories. The results indicate (1) the manipulation of the size of a memory set or of angular disparity affects the intercept of the regression function that relates the times for memory scanning with different set sizes or for mental rotation with different angular disparities and (2) the manipulation of context affects the slope of the regression function that relates the times for detecting a target character under word and nonword conditions. These ratify the regression approach as a useful method for doing mental chronometry.

The role of audience participation and task relevance on change detection during a card trick.

PubMed

Smith, Tim J

2015-01-01

Magicians utilize many techniques for misdirecting audience attention away from the secret sleight of a trick. One technique is to ask an audience member to participate in a trick either physically by asking them to choose a card or cognitively by having them keep track of a card. While such audience participation is an established part of most magic the cognitive mechanisms by which it operates are unknown. Failure to detect changes to objects while passively viewing magic tricks has been shown to be conditional on the changing feature being irrelevant to the current task. How change blindness operates during interactive tasks is unclear but preliminary evidence suggests that relevance of the changing feature may also play a role (Triesch et al., 2003). The present study created a simple on-line card trick inspired by Triesch et al.'s (2003) that allowed playing cards to be instantaneously replaced without distraction or occlusion as participants were either actively sorting the cards (Doing condition) or watching another person perform the task (Watching conditions). Participants were given one of three sets of instructions. The relevance of the card color to the task increased across the three instructions. During half of the trials a card changed color (but retained its number) as it was moving to the stack. Participants were instructed to immediately report such changes. Analysis of the probability of reporting a change revealed that actively performing the sorting task led to more missed changes than passively watching the same task but only when the changing feature was irrelevant to the sorting task. If the feature was relevant during either the pick-up or put-down action change detection was as good as during the watching block. These results confirm the ability of audience participation to create subtle dynamics of attention and perception during a magic trick and hide otherwise striking changes at the center of attention.

The role of audience participation and task relevance on change detection during a card trick

PubMed Central

Smith, Tim J.

2015-01-01

Magicians utilize many techniques for misdirecting audience attention away from the secret sleight of a trick. One technique is to ask an audience member to participate in a trick either physically by asking them to choose a card or cognitively by having them keep track of a card. While such audience participation is an established part of most magic the cognitive mechanisms by which it operates are unknown. Failure to detect changes to objects while passively viewing magic tricks has been shown to be conditional on the changing feature being irrelevant to the current task. How change blindness operates during interactive tasks is unclear but preliminary evidence suggests that relevance of the changing feature may also play a role (Triesch et al., 2003). The present study created a simple on-line card trick inspired by Triesch et al.’s (2003) that allowed playing cards to be instantaneously replaced without distraction or occlusion as participants were either actively sorting the cards (Doing condition) or watching another person perform the task (Watching conditions). Participants were given one of three sets of instructions. The relevance of the card color to the task increased across the three instructions. During half of the trials a card changed color (but retained its number) as it was moving to the stack. Participants were instructed to immediately report such changes. Analysis of the probability of reporting a change revealed that actively performing the sorting task led to more missed changes than passively watching the same task but only when the changing feature was irrelevant to the sorting task. If the feature was relevant during either the pick-up or put-down action change detection was as good as during the watching block. These results confirm the ability of audience participation to create subtle dynamics of attention and perception during a magic trick and hide otherwise striking changes at the center of attention. PMID:25698986

Ecological Virtual Reality Evaluation of Neglect Symptoms (EVENS): Effects of Virtual Scene Complexity in the Assessment of Poststroke Unilateral Spatial Neglect.

PubMed

Ogourtsova, Tatiana; Archambault, Philippe; Sangani, Samir; Lamontagne, Anouk

2018-01-01

Unilateral spatial neglect (USN) is a highly prevalent and disabling poststroke impairment. USN is traditionally assessed with paper-and-pencil tests that lack ecological validity, generalization to real-life situations and are easily compensated for in chronic stages. Virtual reality (VR) can, however, counteract these limitations. We aimed to examine the feasibility of a novel assessment of USN symptoms in a functional shopping activity, the Ecological VR-based Evaluation of Neglect Symptoms (EVENS). EVENS is immersive and consists of simple and complex 3-dimensional scenes depicting grocery shopping shelves, where joystick-based object detection and navigation tasks are performed while seated. Effects of virtual scene complexity on navigational and detection abilities in patients with (USN+, n = 12) and without (USN-, n = 15) USN following a right hemisphere stroke and in age-matched healthy controls (HC, n = 9) were determined. Longer detection times, larger mediolateral deviations from ideal paths and longer navigation times were found in USN+ versus USN- and HC groups, particularly in the complex scene. EVENS detected lateralized and nonlateralized USN-related deficits, performance alterations that were dependent or independent of USN severity, and performance alterations in 3 USN- subjects versus HC. EVENS' environmental changing complexity, along with the functional tasks of far space detection and navigation can potentially be clinically relevant and warrant further empirical investigation. Findings are discussed in terms of attentional models, lateralized versus nonlateralized deficits in USN, and tasks-specific mechanisms.

Visual short-term memory capacity for simple and complex objects.

PubMed

Luria, Roy; Sessa, Paola; Gotler, Alex; Jolicoeur, Pierre; Dell'Acqua, Roberto

2010-03-01

Does the capacity of visual short-term memory (VSTM) depend on the complexity of the objects represented in memory? Although some previous findings indicated lower capacity for more complex stimuli, other results suggest that complexity effects arise during retrieval (due to errors in the comparison process with what is in memory) that is not related to storage limitations of VSTM, per se. We used ERPs to track neuronal activity specifically related to retention in VSTM by measuring the sustained posterior contralateral negativity during a change detection task (which required detecting if an item was changed between a memory and a test array). The sustained posterior contralateral negativity, during the retention interval, was larger for complex objects than for simple objects, suggesting that neurons mediating VSTM needed to work harder to maintain more complex objects. This, in turn, is consistent with the view that VSTM capacity depends on complexity.

Monitoring robot actions for error detection and recovery

NASA Technical Reports Server (NTRS)

Gini, M.; Smith, R.

1987-01-01

Reliability is a serious problem in computer controlled robot systems. Although robots serve successfully in relatively simple applications such as painting and spot welding, their potential in areas such as automated assembly is hampered by programming problems. A program for assembling parts may be logically correct, execute correctly on a simulator, and even execute correctly on a robot most of the time, yet still fail unexpectedly in the face of real world uncertainties. Recovery from such errors is far more complicated than recovery from simple controller errors, since even expected errors can often manifest themselves in unexpected ways. Here, a novel approach is presented for improving robot reliability. Instead of anticipating errors, researchers use knowledge-based programming techniques so that the robot can autonomously exploit knowledge about its task and environment to detect and recover from failures. They describe preliminary experiment of a system that they designed and constructed.

A lightning strike to the head causing a visual cortex defect with simple and complex visual hallucinations

PubMed Central

Kleiter, Ingo; Luerding, Ralf; Diendorfer, Gerhard; Rek, Helga; Bogdahn, Ulrich; Schalke, Berthold

2007-01-01

The case of a 23‐year‐old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was set to a drug‐induced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise recovered largely. Neuropsychological tests revealed deficits in fast visual detection tasks and non‐verbal learning, and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. Four months after the accident, she developed a psychological reaction consisting of nightmares with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning flash were retrospectively retraced. PMID:17369595

A lightning strike to the head causing a visual cortex defect with simple and complex visual hallucinations

PubMed Central

Kleiter, Ingo; Luerding, Ralf; Diendorfer, Gerhard; Rek, Helga; Bogdahn, Ulrich; Schalke, Berthold

2009-01-01

The case of a 23-year-old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was sent into a drug-induced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise largely recovered. Neuropsychological tests revealed deficits in fast visual detection tasks and non-verbal learning and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. At 4 months after the accident, she developed a psychological reaction consisting of nightmares, with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning strike were retrospectively retraced PMID:21734915

The Use of Conjunctions in Cognitively Simple versus Complex Oral L2 Tasks

ERIC Educational Resources Information Center

Michel, Marije C.

2013-01-01

The present study explores the use of conjunctions in simple versus complex argumentative tasks performed by second language (L2) learners as a specific measure for the amount of reasoning involved in task performance. The Cognition Hypothesis (Robinson, 2005) states that an increase in cognitive task complexity promotes improvements in L2…

Scene and human face recognition in the central vision of patients with glaucoma

PubMed Central

Aptel, Florent; Attye, Arnaud; Guyader, Nathalie; Boucart, Muriel; Chiquet, Christophe; Peyrin, Carole

2018-01-01

Primary open-angle glaucoma (POAG) firstly mainly affects peripheral vision. Current behavioral studies support the idea that visual defects of patients with POAG extend into parts of the central visual field classified as normal by static automated perimetry analysis. This is particularly true for visual tasks involving processes of a higher level than mere detection. The purpose of this study was to assess visual abilities of POAG patients in central vision. Patients were assigned to two groups following a visual field examination (Humphrey 24–2 SITA-Standard test). Patients with both peripheral and central defects and patients with peripheral but no central defect, as well as age-matched controls, participated in the experiment. All participants had to perform two visual tasks where low-contrast stimuli were presented in the central 6° of the visual field. A categorization task of scene images and human face images assessed high-level visual recognition abilities. In contrast, a detection task using the same stimuli assessed low-level visual function. The difference in performance between detection and categorization revealed the cost of high-level visual processing. Compared to controls, patients with a central visual defect showed a deficit in both detection and categorization of all low-contrast images. This is consistent with the abnormal retinal sensitivity as assessed by perimetry. However, the deficit was greater for categorization than detection. Patients without a central defect showed similar performances to the controls concerning the detection and categorization of faces. However, while the detection of scene images was well-maintained, these patients showed a deficit in their categorization. This suggests that the simple loss of peripheral vision could be detrimental to scene recognition, even when the information is displayed in central vision. This study revealed subtle defects in the central visual field of POAG patients that cannot be predicted by static automated perimetry assessment using Humphrey 24–2 SITA-Standard test. PMID:29481572

Idiosyncratic characteristics of saccadic eye movements when viewing different visual environments.

PubMed

Andrews, T J; Coppola, D M

1999-08-01

Eye position was recorded in different viewing conditions to assess whether the temporal and spatial characteristics of saccadic eye movements in different individuals are idiosyncratic. Our aim was to determine the degree to which oculomotor control is based on endogenous factors. A total of 15 naive subjects viewed five visual environments: (1) The absence of visual stimulation (i.e. a dark room); (2) a repetitive visual environment (i.e. simple textured patterns); (3) a complex natural scene; (4) a visual search task; and (5) reading text. Although differences in visual environment had significant effects on eye movements, idiosyncrasies were also apparent. For example, the mean fixation duration and size of an individual's saccadic eye movements when passively viewing a complex natural scene covaried significantly with those same parameters in the absence of visual stimulation and in a repetitive visual environment. In contrast, an individual's spatio-temporal characteristics of eye movements during active tasks such as reading text or visual search covaried together, but did not correlate with the pattern of eye movements detected when viewing a natural scene, simple patterns or in the dark. These idiosyncratic patterns of eye movements in normal viewing reveal an endogenous influence on oculomotor control. The independent covariance of eye movements during different visual tasks shows that saccadic eye movements during active tasks like reading or visual search differ from those engaged during the passive inspection of visual scenes.

Inter-subject phase synchronization for exploratory analysis of task-fMRI.

PubMed

Bolt, Taylor; Nomi, Jason S; Vij, Shruti G; Chang, Catie; Uddin, Lucina Q

2018-08-01

Analysis of task-based fMRI data is conventionally carried out using a hypothesis-driven approach, where blood-oxygen-level dependent (BOLD) time courses are correlated with a hypothesized temporal structure. In some experimental designs, this temporal structure can be difficult to define. In other cases, experimenters may wish to take a more exploratory, data-driven approach to detecting task-driven BOLD activity. In this study, we demonstrate the efficiency and power of an inter-subject synchronization approach for exploratory analysis of task-based fMRI data. Combining the tools of instantaneous phase synchronization and independent component analysis, we characterize whole-brain task-driven responses in terms of group-wise similarity in temporal signal dynamics of brain networks. We applied this framework to fMRI data collected during performance of a simple motor task and a social cognitive task. Analyses using an inter-subject phase synchronization approach revealed a large number of brain networks that dynamically synchronized to various features of the task, often not predicted by the hypothesized temporal structure of the task. We suggest that this methodological framework, along with readily available tools in the fMRI community, provides a powerful exploratory, data-driven approach for analysis of task-driven BOLD activity. Copyright © 2018 Elsevier Inc. All rights reserved.

Optimal joint detection and estimation that maximizes ROC-type curves

PubMed Central

Wunderlich, Adam; Goossens, Bart; Abbey, Craig K.

2017-01-01

Combined detection-estimation tasks are frequently encountered in medical imaging. Optimal methods for joint detection and estimation are of interest because they provide upper bounds on observer performance, and can potentially be utilized for imaging system optimization, evaluation of observer efficiency, and development of image formation algorithms. We present a unified Bayesian framework for decision rules that maximize receiver operating characteristic (ROC)-type summary curves, including ROC, localization ROC (LROC), estimation ROC (EROC), free-response ROC (FROC), alternative free-response ROC (AFROC), and exponentially-transformed FROC (EFROC) curves, succinctly summarizing previous results. The approach relies on an interpretation of ROC-type summary curves as plots of an expected utility versus an expected disutility (or penalty) for signal-present decisions. We propose a general utility structure that is flexible enough to encompass many ROC variants and yet sufficiently constrained to allow derivation of a linear expected utility equation that is similar to that for simple binary detection. We illustrate our theory with an example comparing decision strategies for joint detection-estimation of a known signal with unknown amplitude. In addition, building on insights from our utility framework, we propose new ROC-type summary curves and associated optimal decision rules for joint detection-estimation tasks with an unknown, potentially-multiple, number of signals in each observation. PMID:27093544

Optimal Joint Detection and Estimation That Maximizes ROC-Type Curves.

PubMed

Wunderlich, Adam; Goossens, Bart; Abbey, Craig K

2016-09-01

Combined detection-estimation tasks are frequently encountered in medical imaging. Optimal methods for joint detection and estimation are of interest because they provide upper bounds on observer performance, and can potentially be utilized for imaging system optimization, evaluation of observer efficiency, and development of image formation algorithms. We present a unified Bayesian framework for decision rules that maximize receiver operating characteristic (ROC)-type summary curves, including ROC, localization ROC (LROC), estimation ROC (EROC), free-response ROC (FROC), alternative free-response ROC (AFROC), and exponentially-transformed FROC (EFROC) curves, succinctly summarizing previous results. The approach relies on an interpretation of ROC-type summary curves as plots of an expected utility versus an expected disutility (or penalty) for signal-present decisions. We propose a general utility structure that is flexible enough to encompass many ROC variants and yet sufficiently constrained to allow derivation of a linear expected utility equation that is similar to that for simple binary detection. We illustrate our theory with an example comparing decision strategies for joint detection-estimation of a known signal with unknown amplitude. In addition, building on insights from our utility framework, we propose new ROC-type summary curves and associated optimal decision rules for joint detection-estimation tasks with an unknown, potentially-multiple, number of signals in each observation.

Walking delays anticipatory postural adjustments but not reaction times in a choice reaction task.

PubMed

Haridas, C; Gordon, I T; Misiaszek, J E

2005-06-01

During standing, anticipatory postural adjustments (APAs) and focal movements are delayed while performing a choice reaction task, compared with a simple reaction task. We hypothesized that APAs and focal movements of a choice reaction task would be similarly delayed during walking. Furthermore, reaction times are delayed during walking compared with standing. We further hypothesized that APAs and focal movements would be delayed during walking, compared with standing, for both simple and choice reaction tasks. Subjects either walked or stood on a treadmill while holding on to stable handles. They were asked to push or pull on the handles in response to a visual cue. Muscle activity was recorded from muscles of the leg (APA) and arm (RT). Our results were in agreement with previous work showing APA onset was delayed in the choice reaction task compared with the simple reaction task. In addition, the interval between the onset of APA and focal movement activity increased with choice reaction tasks. The task of walking did not delay the onset of focal movement for either the simple or choice reaction tasks. Walking did delay the onset of the APA, but only during choice reaction tasks. The results suggest the added demand of walking does not significantly modify the control of focal arm movements. However, additional attentional demands while walking may compromise anticipatory postural control.

OGUPSA sensor scheduling architecture and algorithm

NASA Astrophysics Data System (ADS)

Zhang, Zhixiong; Hintz, Kenneth J.

1996-06-01

This paper introduces a new architecture for a sensor measurement scheduler as well as a dynamic sensor scheduling algorithm called the on-line, greedy, urgency-driven, preemptive scheduling algorithm (OGUPSA). OGUPSA incorporates a preemptive mechanism which uses three policies, (1) most-urgent-first (MUF), (2) earliest- completed-first (ECF), and (3) least-versatile-first (LVF). The three policies are used successively to dynamically allocate and schedule and distribute a set of arriving tasks among a set of sensors. OGUPSA also can detect the failure of a task to meet a deadline as well as generate an optimal schedule in the sense of minimum makespan for a group of tasks with the same priorities. A side benefit is OGUPSA's ability to improve dynamic load balance among all sensors while being a polynomial time algorithm. Results of a simulation are presented for a simple sensor system.

Arctic cognition: a study of cognitive performance in summer and winter at 69 degrees N

NASA Technical Reports Server (NTRS)

Brennen, T.; Martinussen, M.; Hansen, B. O.; Hjemdal, O.

1999-01-01

Evidence has accumulated over the past 15 years that affect in humans is cyclical. In winter there is a tendency to depression, with remission in summer, and this effect is stronger at higher latitudes. In order to determine whether human cognition is similarly rhythmical, this study investigated the cognitive processes of 100 participants living at 69 degrees N. Participants were tested in summer and winter on a range of cognitive tasks, including verbal memory, attention and simple reaction time tasks. The seasonally counterbalanced design and the very northerly latitude of this study provide optimal conditions for detecting impaired cognitive performance in winter, and the conclusion is negative: of five tasks with seasonal effects, four had disadvantages in summer. Like the menstrual cycle, the circannual cycle appears to influence mood but not cognition.

The role of the amygdala and the basal ganglia in visual processing of central vs. peripheral emotional content.

PubMed

Almeida, Inês; van Asselen, Marieke; Castelo-Branco, Miguel

2013-09-01

In human cognition, most relevant stimuli, such as faces, are processed in central vision. However, it is widely believed that recognition of relevant stimuli (e.g. threatening animal faces) at peripheral locations is also important due to their survival value. Moreover, task instructions have been shown to modulate brain regions involved in threat recognition (e.g. the amygdala). In this respect it is also controversial whether tasks requiring explicit focus on stimulus threat content vs. implicit processing differently engage primitive subcortical structures involved in emotional appraisal. Here we have addressed the role of central vs. peripheral processing in the human amygdala using animal threatening vs. non-threatening face stimuli. First, a simple animal face recognition task with threatening and non-threatening animal faces, as well as non-face control stimuli, was employed in naïve subjects (implicit task). A subsequent task was then performed with the same stimulus categories (but different stimuli) in which subjects were told to explicitly detect threat signals. We found lateralized amygdala responses both to the spatial location of stimuli and to the threatening content of faces depending on the task performed: the right amygdala showed increased responses to central compared to left presented stimuli specifically during the threat detection task, while the left amygdala was better prone to discriminate threatening faces from non-facial displays during the animal face recognition task. Additionally, the right amygdala responded to faces during the threat detection task but only when centrally presented. Moreover, we have found no evidence for superior responses of the amygdala to peripheral stimuli. Importantly, we have found that striatal regions activate differentially depending on peripheral vs. central processing of threatening faces. Accordingly, peripheral processing of these stimuli activated more strongly the putaminal region, while central processing engaged mainly the caudate nucleus. We conclude that the human amygdala has a central bias for face stimuli, and that visual processing recruits different striatal regions, putaminal or caudate based, depending on the task and on whether peripheral or central visual processing is involved. © 2013 Elsevier Ltd. All rights reserved.

Classification of EEG signals to identify variations in attention during motor task execution.

PubMed

Aliakbaryhosseinabadi, Susan; Kamavuako, Ernest Nlandu; Jiang, Ning; Farina, Dario; Mrachacz-Kersting, Natalie

2017-06-01

Brain-computer interface (BCI) systems in neuro-rehabilitation use brain signals to control external devices. User status such as attention affects BCI performance; thus detecting the user's attention drift due to internal or external factors is essential for high detection accuracy. An auditory oddball task was applied to divert the users' attention during a simple ankle dorsiflexion movement. Electroencephalogram signals were recorded from eighteen channels. Temporal and time-frequency features were projected to a lower dimension space and used to analyze the effect of two attention levels on motor tasks in each participant. Then, a global feature distribution was constructed with the projected time-frequency features of all participants from all channels and applied for attention classification during motor movement execution. Time-frequency features led to significantly better classification results with respect to the temporal features, particularly for electrodes located over the motor cortex. Motor cortex channels had a higher accuracy in comparison to other channels in the global discrimination of attention level. Previous methods have used the attention to a task to drive external devices, such as the P300 speller. However, here we focus for the first time on the effect of attention drift while performing a motor task. It is possible to explore user's attention variation when performing motor tasks in synchronous BCI systems with time-frequency features. This is the first step towards an adaptive real-time BCI with an integrated function to reveal attention shifts from the motor task. Copyright © 2017 Elsevier B.V. All rights reserved.

Basic multisensory functions can be acquired after congenital visual pattern deprivation in humans.

PubMed

Putzar, Lisa; Gondan, Matthias; Röder, Brigitte

2012-01-01

People treated for bilateral congenital cataracts offer a model to study the influence of visual deprivation in early infancy on visual and multisensory development. We investigated cross-modal integration capabilities in cataract patients using a simple detection task that provided redundant information to two different senses. In both patients and controls, redundancy gains were consistent with coactivation models, indicating an integrated processing of modality-specific information. This finding is in contrast with recent studies showing impaired higher-level multisensory interactions in cataract patients. The present results suggest that basic cross-modal integrative processes for simple short stimuli do not depend on visual and/or crossmodal input since birth.

Stimulating Mathematical Reasoning with Simple Open-Ended Tasks

ERIC Educational Resources Information Center

West, John

2018-01-01

The importance of mathematical reasoning is unquestioned and providing opportunities for students to become involved in mathematical reasoning is paramount. The open-ended tasks presented incorporate mathematical content explored through the contexts of problem solving and reasoning. This article presents a number of simple tasks that may be…

The Role of Covert Retrieval in Working Memory Span Tasks: Evidence from Delayed Recall Tests

ERIC Educational Resources Information Center

McCabe, David P.

2008-01-01

The current study examined delayed recall of items that had been processed during simple and complex span tasks. Three experiments were reported showing that despite more items being recalled initially from a simple span task (i.e., word span) than a complex span task (i.e., operation span), on a delayed recall test more items were recalled that…

Brain Modularity Mediates the Relation between Task Complexity and Performance

NASA Astrophysics Data System (ADS)

Ye, Fengdan; Yue, Qiuhai; Martin, Randi; Fischer-Baum, Simon; Ramos-Nuã+/-Ez, Aurora; Deem, Michael

Recent work in cognitive neuroscience has focused on analyzing the brain as a network, rather than a collection of independent regions. Prior studies taking this approach have found that individual differences in the degree of modularity of the brain network relate to performance on cognitive tasks. However, inconsistent results concerning the direction of this relationship have been obtained, with some tasks showing better performance as modularity increases, and other tasks showing worse performance. A recent theoretical model suggests that these inconsistencies may be explained on the grounds that high-modularity networks favor performance on simple tasks whereas low-modularity networks favor performance on complex tasks. The current study tests these predictions by relating modularity from resting-state fMRI to performance on a set of behavioral tasks. Complex and simple tasks were defined on the basis of whether they drew on executive attention. Consistent with predictions, we found a negative correlation between individuals' modularity and their performance on the complex tasks but a positive correlation with performance on the simple tasks. The results presented here provide a framework for linking measures of whole brain organization to cognitive processing.

Working alone or in the presence of others: exploring social facilitation in baggage X-ray security screening tasks.

PubMed

Yu, Rui-feng; Wu, Xin

2015-01-01

This study investigated whether the mere presence of a human audience would evoke a social facilitation effect in baggage X-ray security screening tasks. A 2 (target presence: present vs. absent) ×  2 (task complexity: simple vs. complex) ×  2 (social presence: alone vs. human audience) within-subject experiment simulating a real baggage screening task was conducted. This experiment included 20 male participants. The participants' search performance in this task was recorded. The results showed that the presence of a human audience speeded up responses in simple tasks and slowed down responses in complex tasks. However, the social facilitation effect produced by the presence of a human audience had no effect on response accuracy. These findings suggested that the complexity of screening tasks should be considered when designing work organisation modes for security screening tasks. Practitioner summary: This study investigated whether the presence of a human audience could evoke a social facilitation effect in baggage X-ray security screening tasks. An experimental simulation was conducted. The results showed that the presence of a human audience facilitated the search performance of simple tasks and inhibited the performance of complex tasks.

Featural and temporal attention selectively enhance task-appropriate representations in human V1

PubMed Central

Warren, Scott; Yacoub, Essa; Ghose, Geoffrey

2015-01-01

Our perceptions are often shaped by focusing our attention toward specific features or periods of time irrespective of location. We explore the physiological bases of these non-spatial forms of attention by imaging brain activity while subjects perform a challenging change detection task. The task employs a continuously varying visual stimulus that, for any moment in time, selectively activates functionally distinct subpopulations of primary visual cortex (V1) neurons. When subjects are cued to the timing and nature of the change, the mapping of orientation preference across V1 was systematically shifts toward the cued stimulus just prior to its appearance. A simple linear model can explain this shift: attentional changes are selectively targeted toward neural subpopulations representing the attended feature at the times the feature was anticipated. Our results suggest that featural attention is mediated by a linear change in the responses of task-appropriate neurons across cortex during appropriate periods of time. PMID:25501983

The hard fall effect: high working memory capacity leads to a higher, but less robust short-term memory performance.

PubMed

Thomassin, Noémylle; Gonthier, Corentin; Guerraz, Michel; Roulin, Jean-Luc

2015-01-01

Participants with a high working memory span tend to perform better than low spans in a variety of tasks. However, their performance is paradoxically more impaired when they have to perform two tasks at once, a phenomenon that could be labeled the "hard fall effect." The present study tested whether this effect exists in a short-term memory task, and investigated the proposal that the effect is due to high spans using efficient facilitative strategies under simple task conditions. Ninety-eight participants performed a spatial short-term memory task under simple and dual task conditions; stimuli presentation times either allowed for the use of complex facilitative strategies or not. High spans outperformed low spans only under simple task conditions when presentation times allowed for the use of facilitative strategies. These results indicate that the hard fall effect exists on a short-term memory task and may be caused by individual differences in strategy use.

Manual lateralization in macaques: handedness, target laterality and task complexity.

PubMed

Regaiolli, Barbara; Spiezio, Caterina; Vallortigara, Giorgio

2016-01-01

Non-human primates represent models to understand the evolution of handedness in humans. Despite several researches have been investigating non-human primates handedness, few studies examined the relationship between target position, hand preference and task complexity. This study aimed at investigating macaque handedness in relation to target laterality and tastiness, as well as task complexity. Seven pig-tailed macaques (Macaca nemestrina) were involved in three different "two alternative choice" tests: one low-level task and two high-level tasks (HLTs). During the first and the third tests macaques could select a preferred food and a non-preferred food, whereas by modifying the design of the second test, macaques were presented with no-difference alternative per trial. Furthermore, a simple-reaching test was administered to assess hand preference in a social context. Macaques showed hand preference at individual level both in simple and complex tasks, but not in the simple-reaching test. Moreover, target position seemed to affect hand preference in retrieving an object in the low-level task, but not in the HLT. Additionally, individual hand preference seemed to be affected from the tastiness of the item to be retrieved. The results suggest that both target laterality and individual motivation might influence hand preference of macaques, especially in simple tasks.

Intermanual transfer and bilateral cortical plasticity is maintained in older adults after skilled motor training with simple and complex tasks

PubMed Central

Dickins, Daina S. E.; Sale, Martin V.; Kamke, Marc R.

2015-01-01

Intermanual transfer refers to the phenomenon whereby unilateral motor training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that intermanual transfer is attenuated in older adults following training on a simple ballistic movement task, but not after training on a complex task. This study investigated whether differences in plasticity in bilateral motor cortices underlie these differential intermanual transfer effects in older adults. Twenty young (<35 years-old) and older adults (>65 years) trained on a simple (repeated ballistic thumb abduction) and complex (sequential finger-thumb opposition) task in separate sessions. Behavioral performance was used to quantify intermanual transfer between the dominant (trained) and non-dominant (untrained) hands. The amplitude of motor-evoked potentials induced by single pulse transcranial magnetic stimulation was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after unilateral skilled motor training with simple and complex tasks. These performance gains were accompanied by bilateral increases in cortical excitability in both groups for the simple but not the complex task. The findings suggest that advancing age does not necessarily influence the capacity for intermanual transfer after training with the dominant hand. PMID:25999856

Physiological assessment of task underload

NASA Technical Reports Server (NTRS)

Comstock, J. Raymond, Jr.; Harris, Randall L., Sr.; Pope, Alan T.

1988-01-01

The ultimate goal of research efforts directed at underload, boredom, or complacency in high-technology work environments is to detect conditions or states of the operator that can be demonstrated to lead to performance degradation, and then to intervene in the environment to restore acceptable system performance. Physiological measures may provide indices of changes in condition or state of the operator that may be of value in high-technology work environments. The focus of the present study was on the use of physiological measures in the assessment of operator condition or state in a task underload scenario. A fault acknowledgement task characterized by simple repetitive responses with minimal novelty, complexity, and uncertainty was employed to place subjects in a task underload situation. Physiological measures (electrocardiogram (ECG), electroencephalogram (EEG), and pupil diameter) were monitored during task performance over a one-hour test session for 12 subjects. Each of the physiological measures exhibited changes over the test session indicative of decrements in subject arousal level. While high correlations between physiological measures were found across subjects, individual differences between subjects support the use of profiling techniques to establish baselines unique to each subject.

[Is there protection against copying? Thoughts about plagiarism].

PubMed

Schubert, András; Glänzel, Wolfgang

2015-12-13

There are at least two reasons why more and more cases of suspected plagiarism are perceived in the scientific literature. On one hand, the ever increasing pressure for publication makes it easier for authors, reviewers and editors to infringe or overlook this serious ethical misdemeanor; on the other hand, with the development of text analysis software, detecting text similarities has become a simple task. The judgement of actual cases, however, requires well-grounded professional knowledge and prudent human decisions.

Application of a Design Morphology to the MX/OCC Definition of a Fault Detection and Dispatch System.

DTIC Science & Technology

1980-09-01

morphology appears to be effective on an unstructured problem and provides a useful vehicle for clearly defining the functions and tasks that meet the needs...approach used is a structured decision process which was successfully demonstrated in FY 78 on relatively simple mechanical equipment and has now been...including achievement of practical conclusions from the large scale optimization procedures. This design morphology provided a useful vehicle for

Motor-cognitive dual-task deficits in individuals with early-mid stage Huntington disease.

PubMed

Fritz, Nora E; Hamana, Katy; Kelson, Mark; Rosser, Anne; Busse, Monica; Quinn, Lori

2016-09-01

Huntington disease (HD) results in a range of cognitive and motor impairments that progress throughout the disease stages; however, little research has evaluated specific dual-task abilities in this population, and the degree to which they may be related to functional ability. The purpose of this study was to a) examine simple and complex motor-cognitive dual-task performance in individuals with HD, b) determine relationships between dual-task walking ability and disease-specific measures of motor, cognitive and functional ability, and c) examine the relationship of dual-task measures to falls in individuals with HD. Thirty-two individuals with HD were evaluated for simple and complex dual-task ability using the Walking While Talking Test. Demographics and disease-specific measures of motor, cognitive and functional ability were also obtained. Individuals with HD had impairments in simple and complex dual-task ability. Simple dual-task walking was correlated to disease-specific motor scores as well as cognitive performance, but complex dual-task walking was correlated with total functional capacity, as well as a range of cognitive measures. Number of prospective falls was moderately-strongly correlated to dual-task measures. Our results suggest that individuals with HD have impairments in cognitive-motor dual-task ability that are related to disease progression and specifically functional ability. Dual-task measures appear to evaluate a unique construct in individuals with early to mid-stage HD, and may have value in improving the prediction of falls risk in this population. Copyright © 2016 Elsevier B.V. All rights reserved.

Differences in change blindness to real-life scenes in adults with autism spectrum conditions.

PubMed

Ashwin, Chris; Wheelwright, Sally; Baron-Cohen, Simon

2017-01-01

People often fail to detect large changes to visual scenes following a brief interruption, an effect known as 'change blindness'. People with autism spectrum conditions (ASC) have superior attention to detail and better discrimination of targets, and often notice small details that are missed by others. Together these predict people with autism should show enhanced perception of changes in simple change detection paradigms, including reduced change blindness. However, change blindness studies to date have reported mixed results in ASC, which have sometimes included no differences to controls or even enhanced change blindness. Attenuated change blindness has only been reported to date in ASC in children and adolescents, with no study reporting reduced change blindness in adults with ASC. The present study used a change blindness flicker task to investigate the detection of changes in images of everyday life in adults with ASC (n = 22) and controls (n = 22) using a simple change detection task design and full range of original scenes as stimuli. Results showed the adults with ASC had reduced change blindness compared to adult controls for changes to items of marginal interest in scenes, with no group difference for changes to items of central interest. There were no group differences in overall response latencies to correctly detect changes nor in the overall number of missed detections in the experiment. However, the ASC group showed greater missed changes for marginal interest changes of location, showing some evidence of greater change blindness as well. These findings show both reduced change blindness to marginal interest changes in ASC, based on response latencies, as well as greater change blindness to changes of location of marginal interest items, based on detection rates. The findings of reduced change blindness are consistent with clinical reports that people with ASC often notice small changes to less salient items within their environment, and are in-line with theories of enhanced local processing and greater attention to detail in ASC. The findings of lower detection rates for one of the marginal interest conditions may be related to problems in shifting attention or an overly focused attention spotlight.

[Computers in biomedical research: I. Analysis of bioelectrical signals].

PubMed

Vivaldi, E A; Maldonado, P

2001-08-01

A personal computer equipped with an analog-to-digital conversion card is able to input, store and display signals of biomedical interest. These signals can additionally be submitted to ad-hoc software for analysis and diagnosis. Data acquisition is based on the sampling of a signal at a given rate and amplitude resolution. The automation of signal processing conveys syntactic aspects (data transduction, conditioning and reduction); and semantic aspects (feature extraction to describe and characterize the signal and diagnostic classification). The analytical approach that is at the basis of computer programming allows for the successful resolution of apparently complex tasks. Two basic principles involved are the definition of simple fundamental functions that are then iterated and the modular subdivision of tasks. These two principles are illustrated, respectively, by presenting the algorithm that detects relevant elements for the analysis of a polysomnogram, and the task flow in systems that automate electrocardiographic reports.

An Automated, Adaptive Framework for Optimizing Preprocessing Pipelines in Task-Based Functional MRI

PubMed Central

Churchill, Nathan W.; Spring, Robyn; Afshin-Pour, Babak; Dong, Fan; Strother, Stephen C.

2015-01-01

BOLD fMRI is sensitive to blood-oxygenation changes correlated with brain function; however, it is limited by relatively weak signal and significant noise confounds. Many preprocessing algorithms have been developed to control noise and improve signal detection in fMRI. Although the chosen set of preprocessing and analysis steps (the “pipeline”) significantly affects signal detection, pipelines are rarely quantitatively validated in the neuroimaging literature, due to complex preprocessing interactions. This paper outlines and validates an adaptive resampling framework for evaluating and optimizing preprocessing choices by optimizing data-driven metrics of task prediction and spatial reproducibility. Compared to standard “fixed” preprocessing pipelines, this optimization approach significantly improves independent validation measures of within-subject test-retest, and between-subject activation overlap, and behavioural prediction accuracy. We demonstrate that preprocessing choices function as implicit model regularizers, and that improvements due to pipeline optimization generalize across a range of simple to complex experimental tasks and analysis models. Results are shown for brief scanning sessions (<3 minutes each), demonstrating that with pipeline optimization, it is possible to obtain reliable results and brain-behaviour correlations in relatively small datasets. PMID:26161667

Task switching costs in preschool children and adults.

PubMed

Peng, Anna; Kirkham, Natasha Z; Mareschal, Denis

2018-08-01

Past research investigating cognitive flexibility has shown that preschool children make many perseverative errors in tasks that require switching between different sets of rules. However, this inflexibility might not necessarily hold with easier tasks. The current study investigated the developmental differences in cognitive flexibility using a task-switching procedure that compared reaction times and accuracy in 4- and 6-year-olds with those in adults. The experiment involved simple target detection tasks and was intentionally designed in a way that the stimulus and response conflicts were minimal together with a long preparation window. Global mixing costs (performance costs when multiple tasks are relevant in a context), and local switch costs (performance costs due to switching to an alternative task) are typically thought to engage endogenous control processes. If this is the case, we should observe developmental differences with both of these costs. Our results show, however, that when the accuracy was good, there were no age differences in cognitive flexibility (i.e., the ability to manage multiple tasks and to switch between tasks) between children and adults. Even though preschool children had slower reaction times and were less accurate, the mixing and switch costs associated with task switching were not reliably larger for preschool children. Preschool children did, however, show more commission errors and greater response repetition effects than adults, which may reflect differences in inhibitory control. Copyright © 2018 Elsevier Inc. All rights reserved.

Vigilance on the move: video game-based measurement of sustained attention.

PubMed

Szalma, J L; Schmidt, T N; Teo, G W L; Hancock, P A

2014-01-01

Vigilance represents the capacity to sustain attention to any environmental source of information over prolonged periods on watch. Most stimuli used in vigilance research over the previous six decades have been relatively simple and often purport to represent important aspects of detection and discrimination tasks in real-world settings. Such displays are most frequently composed of single stimulus presentations in discrete trials against a uniform, often uncluttered background. The present experiment establishes a dynamic, first-person perspective vigilance task in motion using a video-game environment. 'Vigilance on the move' is thus a new paradigm for the study of sustained attention. We conclude that the stress of vigilance extends to the new paradigm, but whether the performance decrement emerges depends upon specific task parameters. The development of the task, the issues to be resolved and the pattern of performance, perceived workload and stress associated with performing such dynamic vigilance are reported. The present experiment establishes a dynamic, first-person perspective movement-based vigilance task using a video-game environment. 'Vigilance on the move' is thus a new paradigm for the evaluation of sustained attention in operational environments in which individuals move as they monitor their environment. Issues addressed in task development are described.

Impact of task-related changes in heart rate on estimation of hemodynamic response and model fit.

PubMed

Hillenbrand, Sarah F; Ivry, Richard B; Schlerf, John E

2016-05-15

The blood oxygen level dependent (BOLD) signal, as measured using functional magnetic resonance imaging (fMRI), is widely used as a proxy for changes in neural activity in the brain. Physiological variables such as heart rate (HR) and respiratory variation (RV) affect the BOLD signal in a way that may interfere with the estimation and detection of true task-related neural activity. This interference is of particular concern when these variables themselves show task-related modulations. We first establish that a simple movement task reliably induces a change in HR but not RV. In group data, the effect of HR on the BOLD response was larger and more widespread throughout the brain than were the effects of RV or phase regressors. The inclusion of HR regressors, but not RV or phase regressors, had a small but reliable effect on the estimated hemodynamic response function (HRF) in M1 and the cerebellum. We next asked whether the inclusion of a nested set of physiological regressors combining phase, RV, and HR significantly improved the model fit in individual participants' data sets. There was a significant improvement from HR correction in M1 for the greatest number of participants, followed by RV and phase correction. These improvements were more modest in the cerebellum. These results indicate that accounting for task-related modulation of physiological variables can improve the detection and estimation of true neural effects of interest. Copyright © 2016 Elsevier Inc. All rights reserved.

Real-time portable system for fabric defect detection using an ARM processor

NASA Astrophysics Data System (ADS)

Fernandez-Gallego, J. A.; Yañez-Puentes, J. P.; Ortiz-Jaramillo, B.; Alvarez, J.; Orjuela-Vargas, S. A.; Philips, W.

2012-06-01

Modern textile industry seeks to produce textiles as little defective as possible since the presence of defects can decrease the final price of products from 45% to 65%. Automated visual inspection (AVI) systems, based on image analysis, have become an important alternative for replacing traditional inspections methods that involve human tasks. An AVI system gives the advantage of repeatability when implemented within defined constrains, offering more objective and reliable results for particular tasks than human inspection. Costs of automated inspection systems development can be reduced using modular solutions with embedded systems, in which an important advantage is the low energy consumption. Among the possibilities for developing embedded systems, the ARM processor has been explored for acquisition, monitoring and simple signal processing tasks. In a recent approach we have explored the use of the ARM processor for defects detection by implementing the wavelet transform. However, the computation speed of the preprocessing was not yet sufficient for real time applications. In this approach we significantly improve the preprocessing speed of the algorithm, by optimizing matrix operations, such that it is adequate for a real time application. The system was tested for defect detection using different defect types. The paper is focused in giving a detailed description of the basis of the algorithm implementation, such that other algorithms may use of the ARM operations for fast implementations.

Thrive or overload? The effect of task complexity on novices' simulation-based learning.

PubMed

Haji, Faizal A; Cheung, Jeffrey J H; Woods, Nicole; Regehr, Glenn; de Ribaupierre, Sandrine; Dubrowski, Adam

2016-09-01

Fidelity is widely viewed as an important element of simulation instructional design based on its purported relationship with transfer of learning. However, higher levels of fidelity may increase task complexity to a point at which novices' cognitive resources become overloaded. In this experiment, we investigate the effects of variations in task complexity on novices' cognitive load and learning during simulation-based procedural skills training. Thirty-eight medical students were randomly assigned to simulation training on a simple or complex lumbar puncture (LP) task. Participants completed four practice trials on this task (skill acquisition). After 10 days of rest, all participants completed one additional trial on their assigned task (retention) and one trial on a 'very complex' simulation designed to be similar to the complex task (transfer). We assessed LP performance and cognitive load on each trial using multiple measures. In both groups, LP performance improved significantly during skill acquisition (p ≤ 0.047, f = 0.29-0.96) and was maintained at retention. The simple task group demonstrated superior performance compared with the complex task group throughout these phases (p ≤ 0.002, d = 1.13-2.31). Cognitive load declined significantly in the simple task group (p < 0.009, f = 0.48-0.76), but not in the complex task group during skill acquisition, and remained lower at retention (p ≤ 0.024, d = 0.78-1.39). Between retention and transfer, LP performance declined and cognitive load increased in the simple task group, whereas both remained stable in the complex task group. At transfer, no group differences were observed in LP performance and cognitive load, except that the simple task group made significantly fewer breaches of sterility (p = 0.023, d = 0.80). Reduced task complexity was associated with superior LP performance and lower cognitive load during skill acquisition and retention, but mixed results on transfer to a more complex task. These results indicate that task complexity is an important factor that may mediate (via cognitive overload) the relationship between instructional design elements (e.g. fidelity) and simulation-based learning outcomes. © 2016 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

The Structure of Working Memory Abilities across the Adult Life Span

PubMed Central

Hale, Sandra; Rose, Nathan S.; Myerson, Joel; Strube, Michael J; Sommers, Mitchell; Tye-Murray, Nancy; Spehar, Brent

2010-01-01

The present study addresses three questions regarding age differences in working memory: (1) whether performance on complex span tasks decreases as a function of age at a faster rate than performance on simple span tasks; (2) whether spatial working memory decreases at a faster rate than verbal working memory; and (3) whether the structure of working memory abilities is different for different age groups. Adults, ages 20–89 (n=388), performed three simple and three complex verbal span tasks and three simple and three complex spatial memory tasks. Performance on the spatial tasks decreased at faster rates as a function of age than performance on the verbal tasks, but within each domain, performance on complex and simple span tasks decreased at the same rates. Confirmatory factor analyses revealed that domain-differentiated models yielded better fits than models involving domain-general constructs, providing further evidence of the need to distinguish verbal and spatial working memory abilities. Regardless of which domain-differentiated model was examined, and despite the faster rates of decrease in the spatial domain, age group comparisons revealed that the factor structure of working memory abilities was highly similar in younger and older adults and showed no evidence of age-related dedifferentiation. PMID:21299306

Improving EMG based classification of basic hand movements using EMD.

PubMed

Sapsanis, Christos; Georgoulas, George; Tzes, Anthony; Lymberopoulos, Dimitrios

2013-01-01

This paper presents a pattern recognition approach for the identification of basic hand movements using surface electromyographic (EMG) data. The EMG signal is decomposed using Empirical Mode Decomposition (EMD) into Intrinsic Mode Functions (IMFs) and subsequently a feature extraction stage takes place. Various combinations of feature subsets are tested using a simple linear classifier for the detection task. Our results suggest that the use of EMD can increase the discrimination ability of the conventional feature sets extracted from the raw EMG signal.

Design of a Microprogram Control Unit with Concurrent Error Detection.

DTIC Science & Technology

1984-08-01

I fxoot Office of Naval Research N/A N00039-80-C-0556 ta. ADDRESS (City. St.. and ZIP Cod 10. SOURCE OF FUNOING N0. -PROGRAM PROJECT TASK WORK UNIT...However, the CED concept is mainly applied to various codes data transmission, and simple functional units, such as arithmetic units. Little work has...been done in the control unit area. Previous work is primarily in the use of clanical self-checking circuits, using bit slicin& parity, and m-out-of-n

Grid workflow job execution service 'Pilot'

NASA Astrophysics Data System (ADS)

Shamardin, Lev; Kryukov, Alexander; Demichev, Andrey; Ilyin, Vyacheslav

2011-12-01

'Pilot' is a grid job execution service for workflow jobs. The main goal for the service is to automate computations with multiple stages since they can be expressed as simple workflows. Each job is a directed acyclic graph of tasks and each task is an execution of something on a grid resource (or 'computing element'). Tasks may be submitted to any WS-GRAM (Globus Toolkit 4) service. The target resources for the tasks execution are selected by the Pilot service from the set of available resources which match the specific requirements from the task and/or job definition. Some simple conditional execution logic is also provided. The 'Pilot' service is built on the REST concepts and provides a simple API through authenticated HTTPS. This service is deployed and used in production in a Russian national grid project GridNNN.

Writer's cramp: increased dorsal premotor activity during intended writing.

PubMed

Delnooz, Cathérine C S; Helmich, Rick C; Medendorp, W P; Van de Warrenburg, Bart P C; Toni, Ivan

2013-03-01

Simple writer's cramp (WC) is a task-specific form of dystonia, characterized by abnormal movements and postures of the hand during writing. It is extremely task-specific, since dystonic symptoms can occur when a patient uses a pencil for writing, but not when it is used for sharpening. Maladaptive plasticity, loss of inhibition, and abnormal sensory processing are important pathophysiological elements of WC. However, it remains unclear how those elements can account for its task-specificity. We used fMRI to isolate cerebral alterations associated with the task-specificity of simple WC. Subjects (13 simple WC patients, 20 matched controls) imagined grasping a pencil to either write with it or sharpen it. On each trial, we manipulated the pencil's position and the number of imagined movements, while monitoring variations in motor output with electromyography. We show that simple WC is characterized by abnormally increased activity in the dorsal premotor cortex (PMd) when imagined actions are specifically related to writing. This cerebral effect was independent from the known deficits in dystonia in generating focal motor output and in processing somatosensory feedback. This abnormal activity of the PMd suggests that the task-specific element of simple WC is primarily due to alterations at the planning level, in the computations that transform a desired action outcome into the motor commands leading to that action. These findings open the way for testing the therapeutic value of interventions that take into account the computational substrate of task-specificity in simple WC, e.g. modulations of PMd activity during the planning phase of writing. Copyright © 2011 Wiley Periodicals, Inc.

From simple desires to ordinary beliefs: the early development of everyday psychology.

PubMed

Wellman, H M; Woolley, J D

1990-06-01

We provide evidence for the claim that before young children construe human action in terms of beliefs and desires they understand action only in terms of simple desires. This type of naive psychology--a simple desire psychology--constitutes a coherent understanding of human action, but it differs from the belief--desire psychology of slightly older children and adults. In this paper we characterize what we mean by a simple desire psychology and report two experiments. In Experiment 1 we demonstrate that 2-year-old can predict actions and reactions related to simple desires. In Experiment 2 we demonstrate that many 2-year-old pass desire reasoning tasks while at the same time failing belief reasoning tasks that are passed by slightly older children, and that are as comparable as possible to the desire tasks they pass with ease.

High levels of time contraction in young children in dual tasks are related to their limited attention capacities.

PubMed

Hallez, Quentin; Droit-Volet, Sylvie

2017-09-01

Numerous studies have shown that durations are judged shorter in a dual-task condition than in a simple-task condition. The resource-based theory of time perception suggests that this is due to the processing of temporal information, which is a demanding cognitive task that consumes limited attention resources. Our study investigated whether this time contraction in a dual-task condition is greater in younger children and, if so, whether this is specifically related to their limited attention capacities. Children aged 5-7years were given a temporal reproduction task in a simple-task condition and a dual-task condition. In addition, different neuropsychological tests were used to assess not only their attention capacities but also their capacities in terms of working memory and information processing speed. The results showed a shortening of perceived time in the dual task compared with the simple task, and this increased as age decreased. The extent of this shortening effect was directly linked to younger children's limited attentional capacities; the lower their attentional capacities, the greater the time contraction. This study demonstrated that children's errors in time judgments are linked to their cognitive capacities rather than to capacities that are specific to time. Copyright © 2017 Elsevier Inc. All rights reserved.

Unilateral neglect: further validation of the baking tray task.

PubMed

Appelros, Peter; Karlsson, Gunnel M; Thorwalls, Annika; Tham, Kerstin; Nydevik, Ingegerd

2004-11-01

The Baking Tray Task is a comprehensible, simple-to-perform test for use in assessing unilateral neglect. The aim of this study was to validate further its use with stroke patients. The Baking Tray Task was compared with 2 versions of the Behaviour Inattention Test and a test for personal neglect. A total of 270 patients were subjected to a 3-item version of the Behaviour Inattention Test and 40 patients were subjected to an 8-item version of the Behaviour Inattention Test, besides the Baking Tray Task and the personal neglect test. The Baking Tray Task was more sensitive than the 3-item Behaviour Inattention Test, but the 8-item Behaviour Inattention Test was more sensitive than the Baking Tray Task. The best combination of any 3 tests was Baking Tray Task, Reading an article, and Figure copying; the 2 last-mentioned being a part of the 8-item Behaviour Inattention Test. Multi-item tests detect more cases of neglect than do single tests. However, it is tiresome for the patient to undergo a larger test battery than necessary. It is also time-consuming for the staff. Behavioural tests seem more appropriate when assessing neglect. The Baking Tray Task seems to be one of the most sensitive single tests, but its sensitivity can be further enhanced when it is used in combination with other tests.

Cascaded systems analysis of noise and detectability in dual-energy cone-beam CT

PubMed Central

Gang, Grace J.; Zbijewski, Wojciech; Webster Stayman, J.; Siewerdsen, Jeffrey H.

2012-01-01

Purpose: Dual-energy computed tomography and dual-energy cone-beam computed tomography (DE-CBCT) are promising modalities for applications ranging from vascular to breast, renal, hepatic, and musculoskeletal imaging. Accordingly, the optimization of imaging techniques for such applications would benefit significantly from a general theoretical description of image quality that properly incorporates factors of acquisition, reconstruction, and tissue decomposition in DE tomography. This work reports a cascaded systems analysis model that includes the Poisson statistics of x rays (quantum noise), detector model (flat-panel detectors), anatomical background, image reconstruction (filtered backprojection), DE decomposition (weighted subtraction), and simple observer models to yield a task-based framework for DE technique optimization. Methods: The theoretical framework extends previous modeling of DE projection radiography and CBCT. Signal and noise transfer characteristics are propagated through physical and mathematical stages of image formation and reconstruction. Dual-energy decomposition was modeled according to weighted subtraction of low- and high-energy images to yield the 3D DE noise-power spectrum (NPS) and noise-equivalent quanta (NEQ), which, in combination with observer models and the imaging task, yields the dual-energy detectability index (d′). Model calculations were validated with NPS and NEQ measurements from an experimental imaging bench simulating the geometry of a dedicated musculoskeletal extremities scanner. Imaging techniques, including kVp pair and dose allocation, were optimized using d′ as an objective function for three example imaging tasks: (1) kidney stone discrimination; (2) iodine vs bone in a uniform, soft-tissue background; and (3) soft tissue tumor detection on power-law anatomical background. Results: Theoretical calculations of DE NPS and NEQ demonstrated good agreement with experimental measurements over a broad range of imaging conditions. Optimization results suggest a lower fraction of total dose imparted by the low-energy acquisition, a finding consistent with previous literature. The selection of optimal kVp pair reveals the combined effect of both quantum noise and contrast in the kidney stone discrimination and soft-tissue tumor detection tasks, whereas the K-edge effect of iodine was the dominant factor in determining kVp pairs in the iodine vs bone task. The soft-tissue tumor task illustrated the benefit of dual-energy imaging in eliminating anatomical background noise and improving detectability beyond that achievable by single-energy scans. Conclusions: This work established a task-based theoretical framework that is predictive of DE image quality. The model can be utilized in optimizing a broad range of parameters in image acquisition, reconstruction, and decomposition, providing a useful tool for maximizing DE-CBCT image quality and reducing dose. PMID:22894440

Chasing the silver bullet: measuring driver fatigue using simple and complex tasks.

PubMed

Baulk, S D; Biggs, S N; Reid, K J; van den Heuvel, C J; Dawson, D

2008-01-01

Driver fatigue remains a significant cause of motor-vehicle accidents worldwide. New technologies are increasingly utilised to improve road safety, but there are no effective on-road measures for fatigue. While simulated driving tasks are sensitive, and simple performance tasks have been used in industrial fatigue management systems (FMS) to quantify risk, little is known about the relationship between such measures. Establishing a simple, on-road measure of fatigue, as a fitness-to-drive tool, is an important issue for road safety and accident prevention, particularly as many fatigue related accidents are preventable. This study aimed to measure fatigue-related performance decrements using a simple task (reaction time - RT) and a complex task (driving simulation), and to determine the potential for a link between such measures, thus improving FMS success. Fifteen volunteer participants (7 m, 8 f) aged 22-56 years (mean 33.6 years), underwent 26 h of supervised wakefulness before an 8h recovery sleep opportunity. Participants were tested using a 30-min interactive driving simulation test, bracketed by a 10-min psychomotor vigilance task (PVT) at 4, 8, 18 and 24h of wakefulness, and following recovery sleep. Extended wakefulness caused significant decrements in PVT and driving performance. Although these measures are clearly linked, our analyses suggest that driving simulation cannot be replaced by a simple PVT. Further research is needed to closely examine links between performance measures, and to facilitate accurate management of fitness to drive, which requires more complex assessments of performance than RT alone.

Functional Dissociation of Latency-Variable, Stimulus- and Response-Locked Target P3 Sub-components in Task-Switching.

PubMed

Brydges, Christopher R; Barceló, Francisco

2018-01-01

Cognitive control warrants efficient task performance in dynamic and changing environments through adjustments in executive attention, stimulus and response selection. The well-known P300 component of the human event-related potential (ERP) has long been proposed to index "context-updating"-critical for cognitive control-in simple target detection tasks. However, task switching ERP studies have revealed both target P3 (300-350 ms) and later sustained P3-like potentials (400-1,200 ms) to first targets ensuing transition cues, although it remains unclear whether these target P3-like potentials also reflect context updating operations. To address this question, we applied novel single-trial EEG analyses-residue iteration decomposition (RIDE)-in order to disentangle target P3 sub-components in a sample of 22 young adults while they either repeated or switched (updated) task rules. The rationale was to revise the context updating hypothesis of P300 elicitation in the light of new evidence suggesting that "the context" consists of not only the sensory units of stimulation, but also associated motor units, and intermediate low- and high-order sensorimotor units, all of which may need to be dynamically updated on a trial by trial basis. The results showed functionally distinct target P3-like potentials in stimulus-locked, response-locked, and intermediate RIDE component clusters overlying parietal and frontal regions, implying multiple functionally distinct, though temporarily overlapping context updating operations. These findings support a reformulated version of the context updating hypothesis, and reveal a rich family of distinct target P3-like sub-components during the reactive control of target detection in task-switching, plausibly indexing the complex and dynamic workings of frontoparietal cortical networks subserving cognitive control.

Functional Dissociation of Latency-Variable, Stimulus- and Response-Locked Target P3 Sub-components in Task-Switching

PubMed Central

Brydges, Christopher R.; Barceló, Francisco

2018-01-01

Cognitive control warrants efficient task performance in dynamic and changing environments through adjustments in executive attention, stimulus and response selection. The well-known P300 component of the human event-related potential (ERP) has long been proposed to index “context-updating”—critical for cognitive control—in simple target detection tasks. However, task switching ERP studies have revealed both target P3 (300–350 ms) and later sustained P3-like potentials (400–1,200 ms) to first targets ensuing transition cues, although it remains unclear whether these target P3-like potentials also reflect context updating operations. To address this question, we applied novel single-trial EEG analyses—residue iteration decomposition (RIDE)—in order to disentangle target P3 sub-components in a sample of 22 young adults while they either repeated or switched (updated) task rules. The rationale was to revise the context updating hypothesis of P300 elicitation in the light of new evidence suggesting that “the context” consists of not only the sensory units of stimulation, but also associated motor units, and intermediate low- and high-order sensorimotor units, all of which may need to be dynamically updated on a trial by trial basis. The results showed functionally distinct target P3-like potentials in stimulus-locked, response-locked, and intermediate RIDE component clusters overlying parietal and frontal regions, implying multiple functionally distinct, though temporarily overlapping context updating operations. These findings support a reformulated version of the context updating hypothesis, and reveal a rich family of distinct target P3-like sub-components during the reactive control of target detection in task-switching, plausibly indexing the complex and dynamic workings of frontoparietal cortical networks subserving cognitive control. PMID:29515383

Anxiety and selective attention in obsessive-compulsive disorder.

PubMed

Cohen, Yoav; Lachenmeyer, Juliana Rasic; Springer, Craig

2003-11-01

Recently, there has been increasing evidence for information-processing deficits in individuals with obsessive-compulsive disorder (OCD). While impairments in selective attention have been identified to be central to the symptomatology of OCD, the role that situational anxiety plays in attentional processes has not been fully explored. Previous research findings were limited to tasks containing anxiety-relevant materials, only permitting for the evaluation of the impact of anxiety on simultaneous cognitive processing. Furthermore, it has not yet been determined whether the impact of anxiety is limited to selective attention or is indicative of a more general cognitive impairment. This study was designed to examine the role that situational anxiety plays in selective attention impairments. OCD participants and controls were presented with an anxiety producing statement and a neutral statement, followed by the Stroop Task. Results indicated that situational anxiety plays a significant role in the performance of tasks that require selective attention in OCD. A significant deterioration was detected in performance on selective attention tasks for the OCD participants after confronting anxiety-provoking scenarios, as compared to neutral scenarios. Anxiety did not impair performance on simple reading tasks. Possible explanations are discussed.

Local feature saliency classifier for real-time intrusion monitoring

NASA Astrophysics Data System (ADS)

Buch, Norbert; Velastin, Sergio A.

2014-07-01

We propose a texture saliency classifier to detect people in a video frame by identifying salient texture regions. The image is classified into foreground and background in real time. No temporal image information is used during the classification. The system is used for the task of detecting people entering a sterile zone, which is a common scenario for visual surveillance. Testing is performed on the Imagery Library for Intelligent Detection Systems sterile zone benchmark dataset of the United Kingdom's Home Office. The basic classifier is extended by fusing its output with simple motion information, which significantly outperforms standard motion tracking. A lower detection time can be achieved by combining texture classification with Kalman filtering. The fusion approach running at 10 fps gives the highest result of F1=0.92 for the 24-h test dataset. The paper concludes with a detailed analysis of the computation time required for the different parts of the algorithm.

Electro-optical muzzle flash detection

NASA Astrophysics Data System (ADS)

Krieg, Jürgen; Eisele, Christian; Seiffer, Dirk

2016-10-01

Localizing a shooter in a complex scenario is a difficult task. Acoustic sensors can be used to detect blast waves. Radar technology permits detection of the projectile. A third method is to detect the muzzle flash using electro-optical devices. Detection of muzzle flash events is possible with focal plane arrays, line and single element detectors. In this paper, we will show that the detection of a muzzle flash works well in the shortwave infrared spectral range. Important for the acceptance of an operational warning system in daily use is a very low false alarm rate. Using data from a detector with a high sampling rate the temporal signature of a potential muzzle flash event can be analyzed and the false alarm rate can be reduced. Another important issue is the realization of an omnidirectional view required on an operational level. It will be shown that a combination of single element detectors and simple optics in an appropriate configuration is a capable solution.

Use of Speech Analyses within a Mobile Application for the Assessment of Cognitive Impairment in Elderly People.

PubMed

Konig, Alexandra; Satt, Aharon; Sorin, Alex; Hoory, Ran; Derreumaux, Alexandre; David, Renaud; Robert, Phillippe H

2018-01-01

Various types of dementia and Mild Cognitive Impairment (MCI) are manifested as irregularities in human speech and language, which have proven to be strong predictors for the disease presence and progress ion. Therefore, automatic speech analytics provided by a mobile application may be a useful tool in providing additional indicators for assessment and detection of early stage dementia and MCI. 165 participants (subjects with subjective cognitive impairment (SCI), MCI patients, Alzheimer's disease (AD) and mixed dementia (MD) patients) were recorded with a mobile application while performing several short vocal cognitive tasks during a regular consultation. These tasks included verbal fluency, picture description, counting down and a free speech task. The voice recordings were processed in two steps: in the first step, vocal markers were extracted using speech signal processing techniques; in the second, the vocal markers were tested to assess their 'power' to distinguish between SCI, MCI, AD and MD. The second step included training automatic classifiers for detecting MCI and AD, based on machine learning methods, and testing the detection accuracy. The fluency and free speech tasks obtain the highest accuracy rates of classifying AD vs. MD vs. MCI vs. SCI. Using the data, we demonstrated classification accuracy as follows: SCI vs. AD = 92% accuracy; SCI vs. MD = 92% accuracy; SCI vs. MCI = 86% accuracy and MCI vs. AD = 86%. Our results indicate the potential value of vocal analytics and the use of a mobile application for accurate automatic differentiation between SCI, MCI and AD. This tool can provide the clinician with meaningful information for assessment and monitoring of people with MCI and AD based on a non-invasive, simple and low-cost method. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Gestural cue analysis in automated semantic miscommunication annotation

PubMed Central

Inoue, Masashi; Ogihara, Mitsunori; Hanada, Ryoko; Furuyama, Nobuhiro

2011-01-01

The automated annotation of conversational video by semantic miscommunication labels is a challenging topic. Although miscommunications are often obvious to the speakers as well as the observers, it is difficult for machines to detect them from the low-level features. We investigate the utility of gestural cues in this paper among various non-verbal features. Compared with gesture recognition tasks in human-computer interaction, this process is difficult due to the lack of understanding on which cues contribute to miscommunications and the implicitness of gestures. Nine simple gestural features are taken from gesture data, and both simple and complex classifiers are constructed using machine learning. The experimental results suggest that there is no single gestural feature that can predict or explain the occurrence of semantic miscommunication in our setting. PMID:23585724

TBDQ: A Pragmatic Task-Based Method to Data Quality Assessment and Improvement

PubMed Central

Vaziri, Reza; Mohsenzadeh, Mehran; Habibi, Jafar

2016-01-01

Organizations are increasingly accepting data quality (DQ) as a major key to their success. In order to assess and improve DQ, methods have been devised. Many of these methods attempt to raise DQ by directly manipulating low quality data. Such methods operate reactively and are suitable for organizations with highly developed integrated systems. However, there is a lack of a proactive DQ method for businesses with weak IT infrastructure where data quality is largely affected by tasks that are performed by human agents. This study aims to develop and evaluate a new method for structured data, which is simple and practical so that it can easily be applied to real world situations. The new method detects the potentially risky tasks within a process, and adds new improving tasks to counter them. To achieve continuous improvement, an award system is also developed to help with the better selection of the proposed improving tasks. The task-based DQ method (TBDQ) is most appropriate for small and medium organizations, and simplicity in implementation is one of its most prominent features. TBDQ is case studied in an international trade company. The case study shows that TBDQ is effective in selecting optimal activities for DQ improvement in terms of cost and improvement. PMID:27192547

Color line-scan technology in industrial applications

NASA Astrophysics Data System (ADS)

Lemstrom, Guy F.

1995-10-01

Color machine vision opens new possibilities for industrial on-line quality control applications. With color machine vision it's possible to detect different colors and shades, make color separation, spectroscopic applications and at the same time do measurements in the same way as with gray scale technology. These can be geometrical measurements such as dimensions, shape, texture etc. By combining these technologies in a color line scan camera, it brings the machine vision to new dimensions of realizing new applications and new areas in the machine vision business. Quality and process control requirements in the industry get more demanding every day. Color machine vision can be the solution for many simple tasks that haven't been realized with gray scale technology. The lack of detecting or measuring colors has been one reason why machine vision has not been used in quality control as much as it could have been. Color machine vision has shown a growing enthusiasm in the industrial machine vision applications. Potential areas of the industry include food, wood, mining and minerals, printing, paper, glass, plastic, recycling etc. Tasks are from simple measuring to total process and quality control. The color machine vision is not only for measuring colors. It can also be for contrast enhancement, object detection, background removing, structure detection and measuring. Color or spectral separation can be used in many different ways for working out machine vision application than before. It's only a question of how to use the benefits of having two or more data per measured pixel, instead of having only one as in case with traditional gray scale technology. There are plenty of potential applications already today that can be realized with color vision and it's going to give more performance to many traditional gray scale applications in the near future. But the most important feature is that color machine vision offers a new way of working out applications, where machine vision hasn't been applied before.

Real-Time Performance Feedback for the Manual Control of Spacecraft

NASA Astrophysics Data System (ADS)

Karasinski, John Austin

Real-time performance metrics were developed to quantify workload, situational awareness, and manual task performance for use as visual feedback to pilots of aerospace vehicles. Results from prior lunar lander experiments with variable levels of automation were replicated and extended to provide insights for the development of real-time metrics. Increased levels of automation resulted in increased flight performance, lower workload, and increased situational awareness. Automated Speech Recognition (ASR) was employed to detect verbal callouts as a limited measure of subjects' situational awareness. A one-dimensional manual tracking task and simple instructor-model visual feedback scheme was developed. This feedback was indicated to the operator by changing the color of a guidance element on the primary flight display, similar to how a flight instructor points out elements of a display to a student pilot. Experiments showed that for this low-complexity task, visual feedback did not change subject performance, but did increase the subjects' measured workload. Insights gained from these experiments were applied to a Simplified Aid for EVA Rescue (SAFER) inspection task. The effects of variations of an instructor-model performance-feedback strategy on human performance in a novel SAFER inspection task were investigated. Real-time feedback was found to have a statistically significant effect of improving subject performance and decreasing workload in this complicated four degree of freedom manual control task with two secondary tasks.

A Simple Interactive Software Package for Plotting, Animating, and Calculating

ERIC Educational Resources Information Center

Engelhardt, Larry

2012-01-01

We introduce a new open source (free) software package that provides a simple, highly interactive interface for carrying out certain mathematical tasks that are commonly encountered in physics. These tasks include plotting and animating functions, solving systems of coupled algebraic equations, and basic calculus (differentiating and integrating…

The Structure of Visuospatial Memory in Adulthood

ERIC Educational Resources Information Center

Mammarella, Irene C.; Borella, Erika; Pastore, Massimiliano; Pazzaglia, Francesca

2013-01-01

The present study aimed to investigate the structure of visuospatial memory in adulthood. Adults 40-89 years of age (n = 160) performed simple storage and complex visuospatial span tasks. Simple storage tasks were distinguished into three presentation formats: (i) visual, which involved maintaining shapes and textures; (ii) spatial-sequential,…

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind braille readers.

PubMed

Bhattacharjee, Arindam; Ye, Amanda J; Lisak, Joy A; Vargas, Maria G; Goldreich, Daniel

2010-10-27

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at ∼100 ms intervals, and adjacent raised dots within a character at 50 ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25 ms target tap) and amplitude discrimination (compared with 100 μm reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker, 50 Hz, 50 μm; target-masker delays, ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged but that perceptual processing is accelerated in congenitally blind Braille readers.

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind Braille readers

PubMed Central

Bhattacharjee, Arindam; Ye, Amanda J.; Lisak, Joy A.; Vargas, Maria G.; Goldreich, Daniel

2010-01-01

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at about 100-ms intervals, and adjacent raised dots within a character at 50-ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25-ms target tap) and amplitude discrimination (compared to 100-micron reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker: 50-Hz, 50-micron; target-masker delays ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged, but that perceptual processing is accelerated in congenitally blind Braille readers. PMID:20980584

Task-Driven Orbit Design and Implementation on a Robotic C-Arm System for Cone-Beam CT.

PubMed

Ouadah, S; Jacobson, M; Stayman, J W; Ehtiati, T; Weiss, C; Siewerdsen, J H

2017-03-01

This work applies task-driven optimization to the design of non-circular orbits that maximize imaging performance for a particular imaging task. First implementation of task-driven imaging on a clinical robotic C-arm system is demonstrated, and a framework for orbit calculation is described and evaluated. We implemented a task-driven imaging framework to optimize orbit parameters that maximize detectability index d '. This framework utilizes a specified Fourier domain task function and an analytical model for system spatial resolution and noise. Two experiments were conducted to test the framework. First, a simple task was considered consisting of frequencies lying entirely on the f z -axis (e.g., discrimination of structures oriented parallel to the central axial plane), and a "circle + arc" orbit was incorporated into the framework as a means to improve sampling of these frequencies, and thereby increase task-based detectability. The orbit was implemented on a robotic C-arm (Artis Zeego, Siemens Healthcare). A second task considered visualization of a cochlear implant simulated within a head phantom, with spatial frequency response emphasizing high-frequency content in the ( f y , f z ) plane of the cochlea. An optimal orbit was computed using the task-driven framework, and the resulting image was compared to that for a circular orbit. For the f z -axis task, the circle + arc orbit was shown to increase d ' by a factor of 1.20, with an improvement of 0.71 mm in a 3D edge-spread measurement for edges located far from the central plane and a decrease in streak artifacts compared to a circular orbit. For the cochlear implant task, the resulting orbit favored complementary views of high tilt angles in a 360° orbit, and d ' was increased by a factor of 1.83. This work shows that a prospective definition of imaging task can be used to optimize source-detector orbit and improve imaging performance. The method was implemented for execution of non-circular, task-driven orbits on a clinical robotic C-arm system. The framework is sufficiently general to include both acquisition parameters (e.g., orbit, kV, and mA selection) and reconstruction parameters (e.g., a spatially varying regularizer).

Task-driven orbit design and implementation on a robotic C-arm system for cone-beam CT

NASA Astrophysics Data System (ADS)

Ouadah, S.; Jacobson, M.; Stayman, J. W.; Ehtiati, T.; Weiss, C.; Siewerdsen, J. H.

2017-03-01

Purpose: This work applies task-driven optimization to the design of non-circular orbits that maximize imaging performance for a particular imaging task. First implementation of task-driven imaging on a clinical robotic C-arm system is demonstrated, and a framework for orbit calculation is described and evaluated. Methods: We implemented a task-driven imaging framework to optimize orbit parameters that maximize detectability index d'. This framework utilizes a specified Fourier domain task function and an analytical model for system spatial resolution and noise. Two experiments were conducted to test the framework. First, a simple task was considered consisting of frequencies lying entirely on the fz-axis (e.g., discrimination of structures oriented parallel to the central axial plane), and a "circle + arc" orbit was incorporated into the framework as a means to improve sampling of these frequencies, and thereby increase task-based detectability. The orbit was implemented on a robotic C-arm (Artis Zeego, Siemens Healthcare). A second task considered visualization of a cochlear implant simulated within a head phantom, with spatial frequency response emphasizing high-frequency content in the (fy, fz) plane of the cochlea. An optimal orbit was computed using the task-driven framework, and the resulting image was compared to that for a circular orbit. Results: For the fz-axis task, the circle + arc orbit was shown to increase d' by a factor of 1.20, with an improvement of 0.71 mm in a 3D edge-spread measurement for edges located far from the central plane and a decrease in streak artifacts compared to a circular orbit. For the cochlear implant task, the resulting orbit favored complementary views of high tilt angles in a 360° orbit, and d' was increased by a factor of 1.83. Conclusions: This work shows that a prospective definition of imaging task can be used to optimize source-detector orbit and improve imaging performance. The method was implemented for execution of non-circular, task-driven orbits on a clinical robotic C-arm system. The framework is sufficiently general to include both acquisition parameters (e.g., orbit, kV, and mA selection) and reconstruction parameters (e.g., a spatially varying regularizer).

Neural correlates of the difference between working memory speed and simple sensorimotor speed: an fMRI study.

PubMed

Takeuchi, Hikaru; Sugiura, Motoaki; Sassa, Yuko; Sekiguchi, Atsushi; Yomogida, Yukihito; Taki, Yasuyuki; Kawashima, Ryuta

2012-01-01

The difference between the speed of simple cognitive processes and the speed of complex cognitive processes has various psychological correlates. However, the neural correlates of this difference have not yet been investigated. In this study, we focused on working memory (WM) for typical complex cognitive processes. Functional magnetic resonance imaging data were acquired during the performance of an N-back task, which is a measure of WM for typical complex cognitive processes. In our N-back task, task speed and memory load were varied to identify the neural correlates responsible for the difference between the speed of simple cognitive processes (estimated from the 0-back task) and the speed of WM. Our findings showed that this difference was characterized by the increased activation in the right dorsolateral prefrontal cortex (DLPFC) and the increased functional interaction between the right DLPFC and right superior parietal lobe. Furthermore, the local gray matter volume of the right DLPFC was correlated with participants' accuracy during fast WM tasks, which in turn correlated with a psychometric measure of participants' intelligence. Our findings indicate that the right DLPFC and its related network are responsible for the execution of the fast cognitive processes involved in WM. Identified neural bases may underlie the psychometric differences between the speed with which subjects perform simple cognitive tasks and the speed with which subjects perform more complex cognitive tasks, and explain the previous traditional psychological findings.

The phantom robot - Predictive displays for teleoperation with time delay

NASA Technical Reports Server (NTRS)

Bejczy, Antal K.; Kim, Won S.; Venema, Steven C.

1990-01-01

An enhanced teleoperation technique for time-delayed bilateral teleoperator control is discussed. The control technique selected for time delay is based on the use of a high-fidelity graphics phantom robot that is being controlled in real time (without time delay) against the static task image. Thus, the motion of the phantom robot image on the monitor predicts the motion of the real robot. The real robot's motion will follow the phantom robot's motion on the monitor with the communication time delay implied in the task. Real-time high-fidelity graphics simulation of a PUMA arm is generated and overlaid on the actual camera view of the arm. A simple camera calibration technique is used for calibrated graphics overlay. A preliminary experiment is performed with the predictive display by using a very simple tapping task. The results with this simple task indicate that predictive display enhances the human operator's telemanipulation task performance significantly during free motion when there is a long time delay. It appears, however, that either two-view or stereoscopic predictive displays are necessary for general three-dimensional tasks.

Investigation of Three-Group Classifiers to Fully Automate Detection and Classification of Breast Lesions in an Intelligent CAD Mammography Workstation

DTIC Science & Technology

2007-05-01

evaluation of approximations,” tech. rep., Dep. Sistemes Informàtics i Computació, Univ. Politècnica de València (Spain), 2003. [7] D. C. Edwards, C. E...Maryellen L. Giger, scientific collaborator • Lorenzo Pesce, computer programmer 16 C The Hypervolume under the ROC Hypersurface of “Near-Guessing...the simple model we have just described corresponds in the two-class classification task to ROC analysis performed ‘‘per ARTICLE IN PRESS

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…

Spatial cluster detection using dynamic programming.

PubMed

Sverchkov, Yuriy; Jiang, Xia; Cooper, Gregory F

2012-03-25

The task of spatial cluster detection involves finding spatial regions where some property deviates from the norm or the expected value. In a probabilistic setting this task can be expressed as finding a region where some event is significantly more likely than usual. Spatial cluster detection is of interest in fields such as biosurveillance, mining of astronomical data, military surveillance, and analysis of fMRI images. In almost all such applications we are interested both in the question of whether a cluster exists in the data, and if it exists, we are interested in finding the most accurate characterization of the cluster. We present a general dynamic programming algorithm for grid-based spatial cluster detection. The algorithm can be used for both Bayesian maximum a-posteriori (MAP) estimation of the most likely spatial distribution of clusters and Bayesian model averaging over a large space of spatial cluster distributions to compute the posterior probability of an unusual spatial clustering. The algorithm is explained and evaluated in the context of a biosurveillance application, specifically the detection and identification of Influenza outbreaks based on emergency department visits. A relatively simple underlying model is constructed for the purpose of evaluating the algorithm, and the algorithm is evaluated using the model and semi-synthetic test data. When compared to baseline methods, tests indicate that the new algorithm can improve MAP estimates under certain conditions: the greedy algorithm we compared our method to was found to be more sensitive to smaller outbreaks, while as the size of the outbreaks increases, in terms of area affected and proportion of individuals affected, our method overtakes the greedy algorithm in spatial precision and recall. The new algorithm performs on-par with baseline methods in the task of Bayesian model averaging. We conclude that the dynamic programming algorithm performs on-par with other available methods for spatial cluster detection and point to its low computational cost and extendability as advantages in favor of further research and use of the algorithm.

Spatial cluster detection using dynamic programming

PubMed Central

2012-01-01

Background The task of spatial cluster detection involves finding spatial regions where some property deviates from the norm or the expected value. In a probabilistic setting this task can be expressed as finding a region where some event is significantly more likely than usual. Spatial cluster detection is of interest in fields such as biosurveillance, mining of astronomical data, military surveillance, and analysis of fMRI images. In almost all such applications we are interested both in the question of whether a cluster exists in the data, and if it exists, we are interested in finding the most accurate characterization of the cluster. Methods We present a general dynamic programming algorithm for grid-based spatial cluster detection. The algorithm can be used for both Bayesian maximum a-posteriori (MAP) estimation of the most likely spatial distribution of clusters and Bayesian model averaging over a large space of spatial cluster distributions to compute the posterior probability of an unusual spatial clustering. The algorithm is explained and evaluated in the context of a biosurveillance application, specifically the detection and identification of Influenza outbreaks based on emergency department visits. A relatively simple underlying model is constructed for the purpose of evaluating the algorithm, and the algorithm is evaluated using the model and semi-synthetic test data. Results When compared to baseline methods, tests indicate that the new algorithm can improve MAP estimates under certain conditions: the greedy algorithm we compared our method to was found to be more sensitive to smaller outbreaks, while as the size of the outbreaks increases, in terms of area affected and proportion of individuals affected, our method overtakes the greedy algorithm in spatial precision and recall. The new algorithm performs on-par with baseline methods in the task of Bayesian model averaging. Conclusions We conclude that the dynamic programming algorithm performs on-par with other available methods for spatial cluster detection and point to its low computational cost and extendability as advantages in favor of further research and use of the algorithm. PMID:22443103

[What is hidden behind the Baking Tray Task? Study of sensibility and specificity in right-hemispheric stroke patients].

PubMed

Garcia-Fernandez, Juan; Garcia-Molina, Alberto; Aparicio-Lopez, Celeste; Sanchez-Carrion, Rocío; Ensenat, Antònia; Pena-Casanova, Jordi; Roig-Rovira, Teresa

2015-12-16

Tham and Tegner proposed the Baking Tray Task (BTT) as a fast simple assessment test for detecting spatial negligence. However, very few studies have examined its validity as a diagnostic test. To analyse the diagnostic validity of the BTT by measuring its specificity and sensitivity in a sample of subjects with right hemisphere strokes. Forty-eight patients with right hemisphere vascular lesions were distributed in two groups (negligence group, n = 35; non-negligence group, n = 13) according to the scores obtained in a battery of visuospatial examination tests. The participants' performance on the BTT was compared with that of a healthy control group (n = 12). The results showed a high level of sensitivity of the BTT, but low specificity. The performance on the BTT of eight of the 13 members of the non-negligence group was suggestive of negligence. The BTT has proved to be a sensitive test for the detection of spatial negligence. Yet, based on its low specificity, its use alone as a single diagnostic test is not recommended.

Linear and Non-Linear Visual Feature Learning in Rat and Humans

PubMed Central

Bossens, Christophe; Op de Beeck, Hans P.

2016-01-01

The visual system processes visual input in a hierarchical manner in order to extract relevant features that can be used in tasks such as invariant object recognition. Although typically investigated in primates, recent work has shown that rats can be trained in a variety of visual object and shape recognition tasks. These studies did not pinpoint the complexity of the features used by these animals. Many tasks might be solved by using a combination of relatively simple features which tend to be correlated. Alternatively, rats might extract complex features or feature combinations which are nonlinear with respect to those simple features. In the present study, we address this question by starting from a small stimulus set for which one stimulus-response mapping involves a simple linear feature to solve the task while another mapping needs a well-defined nonlinear combination of simpler features related to shape symmetry. We verified computationally that the nonlinear task cannot be trivially solved by a simple V1-model. We show how rats are able to solve the linear feature task but are unable to acquire the nonlinear feature. In contrast, humans are able to use the nonlinear feature and are even faster in uncovering this solution as compared to the linear feature. The implications for the computational capabilities of the rat visual system are discussed. PMID:28066201

Memory-Based Simple Heuristics as Attribute Substitution: Competitive Tests of Binary Choice Inference Models.

PubMed

Honda, Hidehito; Matsuka, Toshihiko; Ueda, Kazuhiro

2017-05-01

Some researchers on binary choice inference have argued that people make inferences based on simple heuristics, such as recognition, fluency, or familiarity. Others have argued that people make inferences based on available knowledge. To examine the boundary between heuristic and knowledge usage, we examine binary choice inference processes in terms of attribute substitution in heuristic use (Kahneman & Frederick, 2005). In this framework, it is predicted that people will rely on heuristic or knowledge-based inference depending on the subjective difficulty of the inference task. We conducted competitive tests of binary choice inference models representing simple heuristics (fluency and familiarity heuristics) and knowledge-based inference models. We found that a simple heuristic model (especially a familiarity heuristic model) explained inference patterns for subjectively difficult inference tasks, and that a knowledge-based inference model explained subjectively easy inference tasks. These results were consistent with the predictions of the attribute substitution framework. Issues on usage of simple heuristics and psychological processes are discussed. Copyright © 2016 Cognitive Science Society, Inc.

Motivation in vigilance - A test of the goal-setting hypothesis of the effectiveness of knowledge of results.

NASA Technical Reports Server (NTRS)

Warm, J. S.; Riechmann, S. W.; Grasha, A. F.; Seibel, B.

1973-01-01

This study tested the prediction, derived from the goal-setting hypothesis, that the facilitating effects of knowledge of results (KR) in a simple vigilance task should be related directly to the level of the performance standard used to regulate KR. Two groups of Ss received dichotomous KR in terms of whether Ss response times (RTs) to signal detections exceeded a high or low standard of performance. The aperiodic offset of a visual signal was the critical event for detection. The vigil was divided into a training phase followed by testing, during which KR was withdrawn. Knowledge of results enhanced performance in both phases. However, the two standards used to regulate feedback contributed little to these effects.

Working memory deficits in children with reading difficulties: memory span and dual task coordination.

PubMed

Wang, Shinmin; Gathercole, Susan E

2013-05-01

The current study investigated the cause of the reported problems in working memory in children with reading difficulties. Verbal and visuospatial simple and complex span tasks, and digit span and reaction times tasks performed singly and in combination, were administered to 46 children with single word reading difficulties and 45 typically developing children matched for age and nonverbal ability. Children with reading difficulties had pervasive deficits in the simple and complex span tasks and had poorer abilities to coordinate two cognitive demanding tasks. These findings indicate that working memory problems in children with reading difficulties may reflect a core deficit in the central executive. Copyright © 2012 Elsevier Inc. All rights reserved.

A free, easy-to-use, computer-based simple and four-choice reaction time programme: the Deary-Liewald reaction time task.

PubMed

Deary, Ian J; Liewald, David; Nissan, Jack

2011-03-01

Reaction time tasks are used widely in basic and applied psychology. There is a need for an easy-to-use, freely available programme that can run simple and choice reaction time tasks with no special software. We report the development of, and make available, the Deary-Liewald reaction time task. It is initially tested here on 150 participants, aged from 18 to 80, alongside another widely used reaction time device and tests of fluid and crystallised intelligence and processing speed. The new task's parameters perform as expected with respect to age and intelligence differences. The new task's parameters are reliable, and have very high correlations with the existing task. We also provide instructions for downloading and using the new reaction time programme, and we encourage other researchers to use it.

Chapter 6: Essential Orientations and Practices

ERIC Educational Resources Information Center

Roholt, Ross VeLure; Hildreth, R. W.; Baizerman, Michael

2007-01-01

In civic youth work program staff focus on larger outcomes and do not often attend to the importance of seemingly mundane and simple tasks. Young people talk about how these simple tasks have powerful meaning for them and their work even as adult volunteers talked about the challenges of working democratically with young people. To integrate these…

Simple Random Sampling-Based Probe Station Selection for Fault Detection in Wireless Sensor Networks

PubMed Central

Huang, Rimao; Qiu, Xuesong; Rui, Lanlan

2011-01-01

Fault detection for wireless sensor networks (WSNs) has been studied intensively in recent years. Most existing works statically choose the manager nodes as probe stations and probe the network at a fixed frequency. This straightforward solution leads however to several deficiencies. Firstly, by only assigning the fault detection task to the manager node the whole network is out of balance, and this quickly overloads the already heavily burdened manager node, which in turn ultimately shortens the lifetime of the whole network. Secondly, probing with a fixed frequency often generates too much useless network traffic, which results in a waste of the limited network energy. Thirdly, the traditional algorithm for choosing a probing node is too complicated to be used in energy-critical wireless sensor networks. In this paper, we study the distribution characters of the fault nodes in wireless sensor networks, validate the Pareto principle that a small number of clusters contain most of the faults. We then present a Simple Random Sampling-based algorithm to dynamic choose sensor nodes as probe stations. A dynamic adjusting rule for probing frequency is also proposed to reduce the number of useless probing packets. The simulation experiments demonstrate that the algorithm and adjusting rule we present can effectively prolong the lifetime of a wireless sensor network without decreasing the fault detected rate. PMID:22163789

Simple random sampling-based probe station selection for fault detection in wireless sensor networks.

PubMed

Huang, Rimao; Qiu, Xuesong; Rui, Lanlan

2011-01-01

Fault detection for wireless sensor networks (WSNs) has been studied intensively in recent years. Most existing works statically choose the manager nodes as probe stations and probe the network at a fixed frequency. This straightforward solution leads however to several deficiencies. Firstly, by only assigning the fault detection task to the manager node the whole network is out of balance, and this quickly overloads the already heavily burdened manager node, which in turn ultimately shortens the lifetime of the whole network. Secondly, probing with a fixed frequency often generates too much useless network traffic, which results in a waste of the limited network energy. Thirdly, the traditional algorithm for choosing a probing node is too complicated to be used in energy-critical wireless sensor networks. In this paper, we study the distribution characters of the fault nodes in wireless sensor networks, validate the Pareto principle that a small number of clusters contain most of the faults. We then present a Simple Random Sampling-based algorithm to dynamic choose sensor nodes as probe stations. A dynamic adjusting rule for probing frequency is also proposed to reduce the number of useless probing packets. The simulation experiments demonstrate that the algorithm and adjusting rule we present can effectively prolong the lifetime of a wireless sensor network without decreasing the fault detected rate.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality.

PubMed

Grübel, Jascha; Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality

PubMed Central

Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R.

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition. PMID:28915266

TPS In-Flight Health Monitoring Project Progress Report

NASA Technical Reports Server (NTRS)

Kostyk, Chris; Richards, Lance; Hudston, Larry; Prosser, William

2007-01-01

Progress in the development of new thermal protection systems (TPS) is reported. New approaches use embedded lightweight, sensitive, fiber optic strain and temperature sensors within the TPS. Goals of the program are to develop and demonstrate a prototype TPS health monitoring system, develop a thermal-based damage detection algorithm, characterize limits of sensor/system performance, and develop ea methodology transferable to new designs of TPS health monitoring systems. Tasks completed during the project helped establish confidence in understanding of both test setup and the model and validated system/sensor performance in a simple TPS structure. Other progress included complete initial system testing, commencement of the algorithm development effort, generation of a damaged thermal response characteristics database, initial development of a test plan for integration testing of proven FBG sensors in simple TPS structure, and development of partnerships to apply the technology.

A Developmental Learning Approach of Mobile Manipulator via Playing

PubMed Central

Wu, Ruiqi; Zhou, Changle; Chao, Fei; Zhu, Zuyuan; Lin, Chih-Min; Yang, Longzhi

2017-01-01

Inspired by infant development theories, a robotic developmental model combined with game elements is proposed in this paper. This model does not require the definition of specific developmental goals for the robot, but the developmental goals are implied in the goals of a series of game tasks. The games are characterized into a sequence of game modes based on the complexity of the game tasks from simple to complex, and the task complexity is determined by the applications of developmental constraints. Given a current mode, the robot switches to play in a more complicated game mode when it cannot find any new salient stimuli in the current mode. By doing so, the robot gradually achieves it developmental goals by playing different modes of games. In the experiment, the game was instantiated into a mobile robot with the playing task of picking up toys, and the game is designed with a simple game mode and a complex game mode. A developmental algorithm, “Lift-Constraint, Act and Saturate,” is employed to drive the mobile robot move from the simple mode to the complex one. The experimental results show that the mobile manipulator is able to successfully learn the mobile grasping ability after playing simple and complex games, which is promising in developing robotic abilities to solve complex tasks using games. PMID:29046632

Detecting natural occlusion boundaries using local cues

PubMed Central

DiMattina, Christopher; Fox, Sean A.; Lewicki, Michael S.

2012-01-01

Occlusion boundaries and junctions provide important cues for inferring three-dimensional scene organization from two-dimensional images. Although several investigators in machine vision have developed algorithms for detecting occlusions and other edges in natural images, relatively few psychophysics or neurophysiology studies have investigated what features are used by the visual system to detect natural occlusions. In this study, we addressed this question using a psychophysical experiment where subjects discriminated image patches containing occlusions from patches containing surfaces. Image patches were drawn from a novel occlusion database containing labeled occlusion boundaries and textured surfaces in a variety of natural scenes. Consistent with related previous work, we found that relatively large image patches were needed to attain reliable performance, suggesting that human subjects integrate complex information over a large spatial region to detect natural occlusions. By defining machine observers using a set of previously studied features measured from natural occlusions and surfaces, we demonstrate that simple features defined at the spatial scale of the image patch are insufficient to account for human performance in the task. To define machine observers using a more biologically plausible multiscale feature set, we trained standard linear and neural network classifiers on the rectified outputs of a Gabor filter bank applied to the image patches. We found that simple linear classifiers could not match human performance, while a neural network classifier combining filter information across location and spatial scale compared well. These results demonstrate the importance of combining a variety of cues defined at multiple spatial scales for detecting natural occlusions. PMID:23255731

Rule induction performance in amnestic mild cognitive impairment and Alzheimer's dementia: examining the role of simple and biconditional rule learning processes.

PubMed

Oosterman, Joukje M; Heringa, Sophie M; Kessels, Roy P C; Biessels, Geert Jan; Koek, Huiberdina L; Maes, Joseph H R; van den Berg, Esther

2017-04-01

Rule induction tests such as the Wisconsin Card Sorting Test require executive control processes, but also the learning and memorization of simple stimulus-response rules. In this study, we examined the contribution of diminished learning and memorization of simple rules to complex rule induction test performance in patients with amnestic mild cognitive impairment (aMCI) or Alzheimer's dementia (AD). Twenty-six aMCI patients, 39 AD patients, and 32 control participants were included. A task was used in which the memory load and the complexity of the rules were independently manipulated. This task consisted of three conditions: a simple two-rule learning condition (Condition 1), a simple four-rule learning condition (inducing an increase in memory load, Condition 2), and a complex biconditional four-rule learning condition-inducing an increase in complexity and, hence, executive control load (Condition 3). Performance of AD patients declined disproportionately when the number of simple rules that had to be memorized increased (from Condition 1 to 2). An additional increment in complexity (from Condition 2 to 3) did not, however, disproportionately affect performance of the patients. Performance of the aMCI patients did not differ from that of the control participants. In the patient group, correlation analysis showed that memory performance correlated with Condition 1 performance, whereas executive task performance correlated with Condition 2 performance. These results indicate that the reduced learning and memorization of underlying task rules explains a significant part of the diminished complex rule induction performance commonly reported in AD, although results from the correlation analysis suggest involvement of executive control functions as well. Taken together, these findings suggest that care is needed when interpreting rule induction task performance in terms of executive function deficits in these patients.

Investigating the Group-Level Impact of Advanced Dual-Echo fMRI Combinations

PubMed Central

Kettinger, Ádám; Hill, Christopher; Vidnyánszky, Zoltán; Windischberger, Christian; Nagy, Zoltán

2016-01-01

Multi-echo fMRI data acquisition has been widely investigated and suggested to optimize sensitivity for detecting the BOLD signal. Several methods have also been proposed for the combination of data with different echo times. The aim of the present study was to investigate whether these advanced echo combination methods provide advantages over the simple averaging of echoes when state-of-the-art group-level random-effect analyses are performed. Both resting-state and task-based dual-echo fMRI data were collected from 27 healthy adult individuals (14 male, mean age = 25.75 years) using standard echo-planar acquisition methods at 3T. Both resting-state and task-based data were subjected to a standard image pre-processing pipeline. Subsequently the two echoes were combined as a weighted average, using four different strategies for calculating the weights: (1) simple arithmetic averaging, (2) BOLD sensitivity weighting, (3) temporal-signal-to-noise ratio weighting and (4) temporal BOLD sensitivity weighting. Our results clearly show that the simple averaging of data with the different echoes is sufficient. Advanced echo combination methods may provide advantages on a single-subject level but when considering random-effects group level statistics they provide no benefit regarding sensitivity (i.e., group-level t-values) compared to the simple echo-averaging approach. One possible reason for the lack of clear advantages may be that apart from increasing the average BOLD sensitivity at the single-subject level, the advanced weighted averaging methods also inflate the inter-subject variance. As the echo combination methods provide very similar results, the recommendation is to choose between them depending on the availability of time for collecting additional resting-state data or whether subject-level or group-level analyses are planned. PMID:28018165

Exploiting semantics for sensor re-calibration in event detection systems

NASA Astrophysics Data System (ADS)

Vaisenberg, Ronen; Ji, Shengyue; Hore, Bijit; Mehrotra, Sharad; Venkatasubramanian, Nalini

2008-01-01

Event detection from a video stream is becoming an important and challenging task in surveillance and sentient systems. While computer vision has been extensively studied to solve different kinds of detection problems over time, it is still a hard problem and even in a controlled environment only simple events can be detected with a high degree of accuracy. Instead of struggling to improve event detection using image processing only, we bring in semantics to direct traditional image processing. Semantics are the underlying facts that hide beneath video frames, which can not be "seen" directly by image processing. In this work we demonstrate that time sequence semantics can be exploited to guide unsupervised re-calibration of the event detection system. We present an instantiation of our ideas by using an appliance as an example--Coffee Pot level detection based on video data--to show that semantics can guide the re-calibration of the detection model. This work exploits time sequence semantics to detect when re-calibration is required to automatically relearn a new detection model for the newly evolved system state and to resume monitoring with a higher rate of accuracy.

Multilevel Contextual 3-D CNNs for False Positive Reduction in Pulmonary Nodule Detection.

PubMed

Dou, Qi; Chen, Hao; Yu, Lequan; Qin, Jing; Heng, Pheng-Ann

2017-07-01

False positive reduction is one of the most crucial components in an automated pulmonary nodule detection system, which plays an important role in lung cancer diagnosis and early treatment. The objective of this paper is to effectively address the challenges in this task and therefore to accurately discriminate the true nodules from a large number of candidates. We propose a novel method employing three-dimensional (3-D) convolutional neural networks (CNNs) for false positive reduction in automated pulmonary nodule detection from volumetric computed tomography (CT) scans. Compared with its 2-D counterparts, the 3-D CNNs can encode richer spatial information and extract more representative features via their hierarchical architecture trained with 3-D samples. More importantly, we further propose a simple yet effective strategy to encode multilevel contextual information to meet the challenges coming with the large variations and hard mimics of pulmonary nodules. The proposed framework has been extensively validated in the LUNA16 challenge held in conjunction with ISBI 2016, where we achieved the highest competition performance metric (CPM) score in the false positive reduction track. Experimental results demonstrated the importance and effectiveness of integrating multilevel contextual information into 3-D CNN framework for automated pulmonary nodule detection in volumetric CT data. While our method is tailored for pulmonary nodule detection, the proposed framework is general and can be easily extended to many other 3-D object detection tasks from volumetric medical images, where the targeting objects have large variations and are accompanied by a number of hard mimics.

Surgical motion characterization in simulated needle insertion procedures

NASA Astrophysics Data System (ADS)

Holden, Matthew S.; Ungi, Tamas; Sargent, Derek; McGraw, Robert C.; Fichtinger, Gabor

2012-02-01

PURPOSE: Evaluation of surgical performance in image-guided needle insertions is of emerging interest, to both promote patient safety and improve the efficiency and effectiveness of training. The purpose of this study was to determine if a Markov model-based algorithm can more accurately segment a needle-based surgical procedure into its five constituent tasks than a simple threshold-based algorithm. METHODS: Simulated needle trajectories were generated with known ground truth segmentation by a synthetic procedural data generator, with random noise added to each degree of freedom of motion. The respective learning algorithms were trained, and then tested on different procedures to determine task segmentation accuracy. In the threshold-based algorithm, a change in tasks was detected when the needle crossed a position/velocity threshold. In the Markov model-based algorithm, task segmentation was performed by identifying the sequence of Markov models most likely to have produced the series of observations. RESULTS: For amplitudes of translational noise greater than 0.01mm, the Markov model-based algorithm was significantly more accurate in task segmentation than the threshold-based algorithm (82.3% vs. 49.9%, p<0.001 for amplitude 10.0mm). For amplitudes less than 0.01mm, the two algorithms produced insignificantly different results. CONCLUSION: Task segmentation of simulated needle insertion procedures was improved by using a Markov model-based algorithm as opposed to a threshold-based algorithm for procedures involving translational noise.

Assessing residual reasoning ability in overtly non-communicative patients using fMRI☆

PubMed Central

Hampshire, Adam; Parkin, Beth L.; Cusack, Rhodri; Espejo, Davinia Fernández; Allanson, Judith; Kamau, Evelyn; Pickard, John D.; Owen, Adrian M.

2012-01-01

It is now well established that some patients who are diagnosed as being in a vegetative state or a minimally conscious state show reliable signs of volition that may only be detected by measuring neural responses. A pertinent question is whether these patients are also capable of logical thought. Here, we validate an fMRI paradigm that can detect the neural fingerprint of reasoning processes and moreover, can confirm whether a participant derives logical answers. We demonstrate the efficacy of this approach in a physically non-communicative patient who had been shown to engage in mental imagery in response to simple auditory instructions. Our results demonstrate that this individual retains a remarkable capacity for higher cognition, engaging in the reasoning task and deducing logical answers. We suggest that this approach is suitable for detecting residual reasoning ability using neural responses and could readily be adapted to assess other aspects of cognition. PMID:24179769

Learning a locomotor task: with or without errors?

PubMed

Marchal-Crespo, Laura; Schneider, Jasmin; Jaeger, Lukas; Riener, Robert

2014-03-04

Robotic haptic guidance is the most commonly used robotic training strategy to reduce performance errors while training. However, research on motor learning has emphasized that errors are a fundamental neural signal that drive motor adaptation. Thus, researchers have proposed robotic therapy algorithms that amplify movement errors rather than decrease them. However, to date, no study has analyzed with precision which training strategy is the most appropriate to learn an especially simple task. In this study, the impact of robotic training strategies that amplify or reduce errors on muscle activation and motor learning of a simple locomotor task was investigated in twenty two healthy subjects. The experiment was conducted with the MAgnetic Resonance COmpatible Stepper (MARCOS) a special robotic device developed for investigations in the MR scanner. The robot moved the dominant leg passively and the subject was requested to actively synchronize the non-dominant leg to achieve an alternating stepping-like movement. Learning with four different training strategies that reduce or amplify errors was evaluated: (i) Haptic guidance: errors were eliminated by passively moving the limbs, (ii) No guidance: no robot disturbances were presented, (iii) Error amplification: existing errors were amplified with repulsive forces, (iv) Noise disturbance: errors were evoked intentionally with a randomly-varying force disturbance on top of the no guidance strategy. Additionally, the activation of four lower limb muscles was measured by the means of surface electromyography (EMG). Strategies that reduce or do not amplify errors limit muscle activation during training and result in poor learning gains. Adding random disturbing forces during training seems to increase attention, and therefore improve motor learning. Error amplification seems to be the most suitable strategy for initially less skilled subjects, perhaps because subjects could better detect their errors and correct them. Error strategies have a great potential to evoke higher muscle activation and provoke better motor learning of simple tasks. Neuroimaging evaluation of brain regions involved in learning can provide valuable information on observed behavioral outcomes related to learning processes. The impacts of these strategies on neurological patients need further investigations.

Performance in complex motor tasks deteriorates in hyperthermic humans.

PubMed

Piil, Jacob F; Lundbye-Jensen, Jesper; Trangmar, Steven J; Nybo, Lars

2017-01-01

Heat stress, leading to elevations in whole-body temperature, has a marked impact on both physical performance and cognition in ecological settings. Lab experiments confirm this for physically demanding activities, whereas observations are inconsistent for tasks involving cognitive processing of information or decision-making prior to responding. We hypothesized that divergences could relate to task complexity and developed a protocol consisting of 1) simple motor task [TARGET_pinch], 2) complex motor task [Visuo-motor tracking], 3) simple math task [MATH_type], 4) combined motor-math task [MATH_pinch]. Furthermore, visuo-motor tracking performance was assessed both in a separate- and a multipart protocol (complex motor tasks alternating with the three other tasks). Following familiarization, each of the 10 male subjects completed separate and multipart protocols in randomized order in the heat (40°C) or control condition (20°C) with testing at baseline (seated rest) and similar seated position, following exercise-induced hyperthermia (core temperature ∼ 39.5°C in the heat and 38.2°C in control condition). All task scores were unaffected by control exercise or passive heat exposure, but visuo-motor tracking performance was reduced by 10.7 ± 6.5% following exercise-induced hyperthermia when integrated in the multipart protocol and 4.4 ± 5.7% when tested separately (both P < 0.05 ). TARGET_pinch precision declined by 2.6 ± 1.3% ( P < 0.05 ), while no significant changes were observed for the math tasks. These results indicate that heat per se has little impact on simple motor or cognitive test performance, but complex motor performance is impaired by hyperthermia and especially so when multiple tasks are combined.

A simple quality assurance test tool for the visual verification of light and radiation field congruent using electronic portal images device and computed radiography

PubMed Central

2012-01-01

Background The radiation field on most megavoltage radiation therapy units are shown by a light field projected through the collimator by a light source mounted inside the collimator. The light field is traditionally used for patient alignment. Hence it is imperative that the light field is congruent with the radiation field. Method A simple quality assurance tool has been designed for rapid and simple test of the light field and radiation field using electronic portal images device (EPID) or computed radiography (CR). We tested this QA tool using Varian PortalVision and Elekta iViewGT EPID systems and Kodak CR system. Results Both the single and double exposure techniques were evaluated, with double exposure technique providing a better visualization of the light-radiation field markers. The light and radiation congruency could be detected within 1 mm. This will satisfy the American Association of Physicists in Medicine task group report number 142 recommendation of 2 mm tolerance. Conclusion The QA tool can be used with either an EPID or CR to provide a simple and rapid method to verify light and radiation field congruence. PMID:22452821

Make Your Workflows Smarter

NASA Technical Reports Server (NTRS)

Jones, Corey; Kapatos, Dennis; Skradski, Cory

2012-01-01

Do you have workflows with many manual tasks that slow down your business? Or, do you scale back workflows because there are simply too many manual tasks? Basic workflow robots can automate some common tasks, but not everything. This presentation will show how advanced robots called "expression robots" can be set up to perform everything from simple tasks such as: moving, creating folders, renaming, changing or creating an attribute, and revising, to more complex tasks like: creating a pdf, or even launching a session of Creo Parametric and performing a specific modeling task. Expression robots are able to utilize the Java API and Info*Engine to do almost anything you can imagine! Best of all, these tools are supported by PTC and will work with later releases of Windchill. Limited knowledge of Java, Info*Engine, and XML are required. The attendee will learn what task expression robots are capable of performing. The attendee will learn what is involved in setting up an expression robot. The attendee will gain a basic understanding of simple Info*Engine tasks

Subjective Estimation of Task Time and Task Difficulty of Simple Movement Tasks.

PubMed

Chan, Alan H S; Hoffmann, Errol R

2017-01-01

It has been demonstrated in previous work that the same neural structures are used for both imagined and real movements. To provide a strong test of the similarity of imagined and actual movement times, 4 simple movement tasks were used to determine the relationship between estimated task time and actual movement time. The tasks were single-component visually controlled movements, 2-component visually controlled, low index of difficulty (ID) moves and pin-to-hole transfer movements. For each task there was good correspondence between the mean estimated times and actual movement times. In all cases, the same factors determined the actual and estimated movement times: the amplitudes of movement and the IDs of the component movements, however the contribution of each of these variables differed for the imagined and real tasks. Generally, the standard deviations of the estimated times were linearly related to the estimated time values. Overall, the data provide strong evidence for the same neural structures being used for both imagined and actual movements.

Multiloop Manual Control of Dynamic Systems

NASA Technical Reports Server (NTRS)

Hess, R. A.; Mcnally, B. D.

1984-01-01

Human interaction with a simple, multiloop dynamic system in which the human's activity was systematically varied by changing the levels of automation was studied. The control loop structure resulting from the task definition parallels that for any multiloop manual control system, is considered a sterotype. Simple models of the human in the task, and upon extending a technique for describing the manner in which the human subjectively quantifies his opinion of task difficulty were developed. A man in the loop simulation which provides data to support and direct the analytical effort is presented.

Complex Sentence Comprehension and Working Memory in Children With Specific Language Impairment

PubMed Central

Montgomery, James W.; Evans, Julia L.

2015-01-01

Purpose This study investigated the association of 2 mechanisms of working memory (phonological short-term memory [PSTM], attentional resource capacity/allocation) with the sentence comprehension of school-age children with specific language impairment (SLI) and 2 groups of control children. Method Twenty-four children with SLI, 18 age-matched (CA) children, and 16 language- and memory-matched (LMM) children completed a nonword repetition task (PSTM), the competing language processing task (CLPT; resource capacity/allocation), and a sentence comprehension task comprising complex and simple sentences. Results (1) The SLI group performed worse than the CA group on each memory task; (2) all 3 groups showed comparable simple sentence comprehension, but for complex sentences, the SLI and LMM groups performed worse than the CA group; (3) for the SLI group, (a) CLPT correlated with complex sentence comprehension, and (b) nonword repetition correlated with simple sentence comprehension; (4) for CA children, neither memory variable correlated with either sentence type; and (5) for LMM children, only CLPT correlated with complex sentences. Conclusions Comprehension of both complex and simple grammar by school-age children with SLI is a mentally demanding activity, requiring significant working memory resources. PMID:18723601

The Effects of Multimedia Task-Based Language Teaching on EFL Learners' Oral L2 Production

ERIC Educational Resources Information Center

BavaHarji, Madhubala; Gheitanchian, Mehrnaz; Letchumanan, Krishnaveni

2014-01-01

This study examined the effects of tasks, with varying levels of complexity, i.e. simple, + complex and ++ complex tasks on EFL learners' oral production in a multimedia task-based language teaching environment. 57 EFL adult learners carried out a total of 12 tasks, in sets of four tasks within three different themes and different levels of…

Writing kinematics and pen forces in writer's cramp: effects of task and clinical subtype.

PubMed

Schneider, A S; Baur, B; Fürholzer, W; Jasper, I; Marquardt, C; Hermsdörfer, J

2010-11-01

Writer's Cramp (WC) is defined as a task-specific form of focal-hand-dystonia generating hypertonic muscle co-contractions resulting in impaired handwriting. Little is known about kinematic and dynamic characteristics in handwriting in the different subtypes of WC. In this study, kinematic and force analyses were used to compare handwriting capacity of 14 simple, 13 dystonic WC-patients and 14 healthy subjects. The effect of task-complexity was investigated using a simple repetitive writing-task, writing pairs of letters, a sentence and copying a text. In general, patients showed significant deficits in kinematic and force parameters during writing, but no consistent differences between the two subtypes of WC were found. The complexity of writing material modulated writing parameters in all groups, but less complex material did not ameliorate the patients' deficits relative to control subjects. The similarity of deficits in patients with simple and dystonic WC does not support the concept of a unitary progression of deficits causing a switch from simple to dystonic WC. Dystonic WC seems to be characterized by a spread of symptoms independent of severity. Obviously, the deficits concern elementary aspects of writing and are not modulated by more complex aspects. Quantification of writing deficits by simple and short phrases with kinematic and force parameters can substantially improve the characterization of WC. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Information Processing in Memory Tasks.

ERIC Educational Resources Information Center

Johnston, William A.

The intensity of information processing engendered in different phases of standard memory tasks was examined in six experiments. Processing intensity was conceptualized as system capacity consumed, and was measured via a divided-attention procedure in which subjects performed a memory task and a simple reaction-time (RT) task concurrently. The…

The effects of cognitive load on strategic self-handicapping.

PubMed

Silvera, D H

2000-03-01

Past research has demonstrated that observers tend to underestimate the importance of situational determinants (e.g. task difficulty) of the performances of others. This tendency is particularly pronounced when observers are unmotivated, distracted or otherwise 'cognitively busy' while making attributional judgments. The objective of the present research was to determine whether a similar tendency exists when actors are given the opportunity to choose the tasks they will undertake in a self-presentational situation. Sixty-one participants were given a choice between a difficult and a simple task, with cognitive busyness being manipulated while this choice was being made. Cognitively busy participants were significantly more likely to choose the simple task than their non-busy counterparts.

Zooming in on the cause of the perceptual load effect in the go/no-go paradigm.

PubMed

Chen, Zhe; Cave, Kyle R

2016-08-01

Perceptual load theory (Lavie, 2005) claims that attentional capacity that is not used for the current task is allocated to irrelevant distractors. It predicts that if the attentional demands of the current task are high, distractor interference will be low. One particularly powerful demonstration of perceptual load effects on distractor processing relies on a go/no-go cue that is interpreted by either simple feature detection or feature conjunction (Lavie, 1995). However, a possible alternative interpretation of these effects is that the differential degree of distractor processing is caused by how broadly attention is allocated (attentional zoom) rather than to perceptual load. In 4 experiments, we show that when stimuli are arranged to equalize the extent of spatial attention across conditions, distractor interference varies little whether cues are defined by a simple feature or a conjunction, and that the typical perceptual load effect emerges only when attentional zoom can covary with perceptual load. These results suggest that attentional zoom can account for the differential degree of distractor processing traditionally attributed to perceptual load in the go/no-go paradigm. They also provide new insight into how different factors interact to control distractor interference. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Circadian Effects on Simple Components of Complex Task Performance

NASA Technical Reports Server (NTRS)

Clegg, Benjamin A.; Wickens, Christopher D.; Vieane, Alex Z.; Gutzwiller, Robert S.; Sebok, Angelia L.

2015-01-01

The goal of this study was to advance understanding and prediction of the impact of circadian rhythm on aspects of complex task performance during unexpected automation failures, and subsequent fault management. Participants trained on two tasks: a process control simulation, featuring automated support; and a multi-tasking platform. Participants then completed one task in a very early morning (circadian night) session, and the other during a late afternoon (circadian day) session. Small effects of time of day were seen on simple components of task performance, but impacts on more demanding components, such as those that occur following an automation failure, were muted relative to previous studies where circadian rhythm was compounded with sleep deprivation and fatigue. Circadian low participants engaged in compensatory strategies, rather than passively monitoring the automation. The findings and implications are discussed in the context of a model that includes the effects of sleep and fatigue factors.

Modeling Simple Driving Tasks with a One-Boundary Diffusion Model

PubMed Central

Ratcliff, Roger; Strayer, David

2014-01-01

A one-boundary diffusion model was applied to the data from two experiments in which subjects were performing a simple simulated driving task. In the first experiment, the same subjects were tested on two driving tasks using a PC-based driving simulator and the psychomotor vigilance test (PVT). The diffusion model fit the response time (RT) distributions for each task and individual subject well. Model parameters were found to correlate across tasks which suggests common component processes were being tapped in the three tasks. The model was also fit to a distracted driving experiment of Cooper and Strayer (2008). Results showed that distraction altered performance by affecting the rate of evidence accumulation (drift rate) and/or increasing the boundary settings. This provides an interpretation of cognitive distraction whereby conversing on a cell phone diverts attention from the normal accumulation of information in the driving environment. PMID:24297620

Creating Simple Admin Tools Using Info*Engine and Java

NASA Technical Reports Server (NTRS)

Jones, Corey; Kapatos, Dennis; Skradski, Cory; Felkins, J. D.

2012-01-01

PTC has provided a simple way to dynamically interact with Windchill using Info*Engine. This presentation will describe how to create a simple Info*Engine Tasks capable of saving Windchill 10.0 administration of tedious work.

A detailed comparison of optimality and simplicity in perceptual decision-making

PubMed Central

Shen, Shan; Ma, Wei Ji

2017-01-01

Two prominent ideas in the study of decision-making have been that organisms behave near-optimally, and that they use simple heuristic rules. These principles might be operating in different types of tasks, but this possibility cannot be fully investigated without a direct, rigorous comparison within a single task. Such a comparison was lacking in most previous studies, because a) the optimal decision rule was simple; b) no simple suboptimal rules were considered; c) it was unclear what was optimal, or d) a simple rule could closely approximate the optimal rule. Here, we used a perceptual decision-making task in which the optimal decision rule is well-defined and complex, and makes qualitatively distinct predictions from many simple suboptimal rules. We find that all simple rules tested fail to describe human behavior, that the optimal rule accounts well for the data, and that several complex suboptimal rules are indistinguishable from the optimal one. Moreover, we found evidence that the optimal model is close to the true model: first, the better the trial-to-trial predictions of a suboptimal model agree with those of the optimal model, the better that suboptimal model fits; second, our estimate of the Kullback-Leibler divergence between the optimal model and the true model is not significantly different from zero. When observers receive no feedback, the optimal model still describes behavior best, suggesting that sensory uncertainty is implicitly represented and taken into account. Beyond the task and models studied here, our results have implications for best practices of model comparison. PMID:27177259

Automatic Sea Bird Detection from High Resolution Aerial Imagery

NASA Astrophysics Data System (ADS)

Mader, S.; Grenzdörffer, G. J.

2016-06-01

Great efforts are presently taken in the scientific community to develop computerized and (fully) automated image processing methods allowing for an efficient and automatic monitoring of sea birds and marine mammals in ever-growing amounts of aerial imagery. Currently the major part of the processing, however, is still conducted by especially trained professionals, visually examining the images and detecting and classifying the requested subjects. This is a very tedious task, particularly when the rate of void images regularly exceeds the mark of 90%. In the content of this contribution we will present our work aiming to support the processing of aerial images by modern methods from the field of image processing. We will especially focus on the combination of local, region-based feature detection and piecewise global image segmentation for automatic detection of different sea bird species. Large image dimensions resulting from the use of medium and large-format digital cameras in aerial surveys inhibit the applicability of image processing methods based on global operations. In order to efficiently handle those image sizes and to nevertheless take advantage of globally operating segmentation algorithms, we will describe the combined usage of a simple performant feature detector based on local operations on the original image with a complex global segmentation algorithm operating on extracted sub-images. The resulting exact segmentation of possible candidates then serves as a basis for the determination of feature vectors for subsequent elimination of false candidates and for classification tasks.

Contrast discrimination, non-uniform patterns and change blindness.

PubMed Central

Scott-Brown, K C; Orbach, H S

1998-01-01

Change blindness--our inability to detect large changes in natural scenes when saccades, blinks and other transients interrupt visual input--seems to contradict psychophysical evidence for our exquisite sensitivity to contrast changes. Can the type of effects described as 'change blindness' be observed with simple, multi-element stimuli, amenable to psychophysical analysis? Such stimuli, composed of five mixed contrast elements, elicited a striking increase in contrast increment thresholds compared to those for an isolated element. Cue presentation prior to the stimulus substantially reduced thresholds, as for change blindness with natural scenes. On one hand, explanations for change blindness based on abstract and sketchy representations in short-term visual memory seem inappropriate for this low-level image property of contrast where there is ample evidence for exquisite performance on memory tasks. On the other hand, the highly increased thresholds for mixed contrast elements, and the decreased thresholds when a cue is present, argue against any simple early attentional or sensory explanation for change blindness. Thus, psychophysical results for very simple patterns cannot straightforwardly predict results even for the slightly more complicated patterns studied here. PMID:9872004

Obesity-specific neural cost of maintaining gait performance under complex conditions in community-dwelling older adults.

PubMed

Osofundiya, Olufunmilola; Benden, Mark E; Dowdy, Diane; Mehta, Ranjana K

2016-06-01

Recent evidence of obesity-related changes in the prefrontal cortex during cognitive and seated motor activities has surfaced; however, the impact of obesity on neural activity during ambulation remains unclear. The purpose of this study was to determine obesity-specific neural cost of simple and complex ambulation in older adults. Twenty non-obese and obese individuals, 65years and older, performed three tasks varying in the types of complexity of ambulation (simple walking, walking+cognitive dual-task, and precision walking). Maximum oxygenated hemoglobin, a measure of neural activity, was measured bilaterally using a portable functional near infrared spectroscopy system, and gait speed and performance on the complex tasks were also obtained. Complex ambulatory tasks were associated with ~2-3.5 times greater cerebral oxygenation levels and ~30-40% slower gait speeds when compared to the simple walking task. Additionally, obesity was associated with three times greater oxygenation levels, particularly during the precision gait task, despite obese adults demonstrating similar gait speeds and performances on the complex gait tasks as non-obese adults. Compared to existing studies that focus solely on biomechanical outcomes, the present study is one of the first to examine obesity-related differences in neural activity during ambulation in older adults. In order to maintain gait performance, obesity was associated with higher neural costs, and this was augmented during ambulatory tasks requiring greater precision control. These preliminary findings have clinical implications in identifying individuals who are at greater risk of mobility limitations, particularly when performing complex ambulatory tasks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Inverted-U Function Relating Cortical Plasticity and Task Difficulty

PubMed Central

Engineer, Navzer D.; Engineer, Crystal T.; Reed, Amanda C.; Pandya, Pritesh K.; Jakkamsetti, Vikram; Moucha, Raluca; Kilgard, Michael P.

2012-01-01

Many psychological and physiological studies with simple stimuli have suggested that perceptual learning specifically enhances the response of primary sensory cortex to task-relevant stimuli. The aim of this study was to determine whether auditory discrimination training on complex tasks enhances primary auditory cortex responses to a target sequence relative to non-target and novel sequences. We collected responses from more than 2,000 sites in 31 rats trained on one of six discrimination tasks that differed primarily in the similarity of the target and distractor sequences. Unlike training with simple stimuli, long-term training with complex stimuli did not generate target specific enhancement in any of the groups. Instead, cortical receptive field size decreased, latency decreased, and paired pulse depression decreased in rats trained on the tasks of intermediate difficulty while tasks that were too easy or too difficult either did not alter or degraded cortical responses. These results suggest an inverted-U function relating neural plasticity and task difficulty. PMID:22249158

How do we watch images? A case of change detection and quality estimation

NASA Astrophysics Data System (ADS)

Radun, Jenni; Leisti, Tuomas; Virtanen, Toni; Nyman, Göte

2012-01-01

The most common tasks in subjective image estimation are change detection (a detection task) and image quality estimation (a preference task). We examined how the task influences the gaze behavior when comparing detection and preference tasks. The eye movements of 16 naïve observers were recorded with 8 observers in both tasks. The setting was a flicker paradigm, where the observers see a non-manipulated image, a manipulated version of the image and again the non-manipulated image and estimate the difference they perceived in them. The material was photographic material with different image distortions and contents. To examine the spatial distribution of fixations, we defined the regions of interest using a memory task and calculated information entropy to estimate how concentrated the fixations were on the image plane. The quality task was faster and needed fewer fixations and the first eight fixations were more concentrated on certain image areas than the change detection task. The bottom-up influences of the image also caused more variation to the gaze behavior in the quality estimation task than in the change detection task The results show that the quality estimation is faster and the regions of interest are emphasized more on certain images compared with the change detection task that is a scan task where the whole image is always thoroughly examined. In conclusion, in subjective image estimation studies it is important to think about the task.

New Fluorescent Nanoparticles for Ultrasensitive Detection of Nucleic Acids by Optical Methods.

PubMed

Westergaard Mulberg, Mads; Taskova, Maria; Thomsen, Rasmus P; Okholm, Anders H; Kjems, Jørgen; Astakhova, Kira

2017-08-17

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification-free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra-bright macrofluorophores of 9-84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target-specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Signal Detection and Monitoring Based on Longitudinal Healthcare Data

PubMed Central

Suling, Marc; Pigeot, Iris

2012-01-01

Post-marketing detection and surveillance of potential safety hazards are crucial tasks in pharmacovigilance. To uncover such safety risks, a wide set of techniques has been developed for spontaneous reporting data and, more recently, for longitudinal data. This paper gives a broad overview of the signal detection process and introduces some types of data sources typically used. The most commonly applied signal detection algorithms are presented, covering simple frequentistic methods like the proportional reporting rate or the reporting odds ratio, more advanced Bayesian techniques for spontaneous and longitudinal data, e.g., the Bayesian Confidence Propagation Neural Network or the Multi-item Gamma-Poisson Shrinker and methods developed for longitudinal data only, like the IC temporal pattern detection. Additionally, the problem of adjustment for underlying confounding is discussed and the most common strategies to automatically identify false-positive signals are addressed. A drug monitoring technique based on Wald’s sequential probability ratio test is presented. For each method, a real-life application is given, and a wide set of literature for further reading is referenced. PMID:24300373

Classification with an edge: Improving semantic image segmentation with boundary detection

NASA Astrophysics Data System (ADS)

Marmanis, D.; Schindler, K.; Wegner, J. D.; Galliani, S.; Datcu, M.; Stilla, U.

2018-01-01

We present an end-to-end trainable deep convolutional neural network (DCNN) for semantic segmentation with built-in awareness of semantically meaningful boundaries. Semantic segmentation is a fundamental remote sensing task, and most state-of-the-art methods rely on DCNNs as their workhorse. A major reason for their success is that deep networks learn to accumulate contextual information over very large receptive fields. However, this success comes at a cost, since the associated loss of effective spatial resolution washes out high-frequency details and leads to blurry object boundaries. Here, we propose to counter this effect by combining semantic segmentation with semantically informed edge detection, thus making class boundaries explicit in the model. First, we construct a comparatively simple, memory-efficient model by adding boundary detection to the SEGNET encoder-decoder architecture. Second, we also include boundary detection in FCN-type models and set up a high-end classifier ensemble. We show that boundary detection significantly improves semantic segmentation with CNNs in an end-to-end training scheme. Our best model achieves >90% overall accuracy on the ISPRS Vaihingen benchmark.

One-step sonochemical synthesis of 1D β-stannous tungstate nanorods: An efficient and excellent electrocatalyst for the selective electrochemical detection of antipsychotic drug chlorpromazine.

PubMed

Kokulnathan, Thangavelu; Kumar, Jeyaraj Vinoth; Chen, Shen-Ming; Karthik, Raj; Elangovan, Arumugam; Muthuraj, Velluchamy

2018-06-01

In the modern world, the contamination of ecosystem by human and veterinary pharmaceutical drugs through the metabolic excretion, improper disposal/industrial waste has been subjected to a hot issue. Therefore, exploitation of exclusive structured material and reliable technique is a necessary task to the precise detection of drugs. With this regards, we made an effort for the fabrication of novel one-dimensional (1D) stannous tungstate nanorods (β-SnW NRs) via simple sonochemical approach and used as an electrochemical sensor for the detection of antipsychotic drug chlorpromazine (CPZ) for the first time. The crystallographic structure, surface topology, elemental compositions and their distributions and ionic states were enquired by different spectroscopic techniques such as XRD, FTIR, SEM, EDS, elemental mapping and XPS analysis. The developed β-SnW NRs/GCE sensor exhibits a rapid and sensitive electrochemical response towards CPZ sensing with wide linear response range (0.01-457 µM), high sensitivity (2.487 µA µM -1  cm -2 ), low detection limit (0.003 µM) and excellent selectivity. Besides, the as-proposed electrochemical sensor was successfully applied to real sample analysis in commercial CPZ drug and biological fluids and the acquired recovery results are quite satisfactory. The proposed sonochemical method for the preparation of β-SnW NRs is low cost, very simple, fast and efficient for sensor applications. Copyright © 2018 Elsevier B.V. All rights reserved.

An Investigation of the Use of Real-time Image Mosaicing for Facilitating Global Spatial Awareness in Visual Search

NASA Astrophysics Data System (ADS)

Soung Yee, Anthony

Three experiments have been completed to investigate whether and how a software technique called real-time image mosaicing applied to a restricted field of view (FOV) might influence target detection and path integration performance in simulated aerial search scenarios, representing local and global spatial awareness tasks respectively. The mosaiced FOV (mFOV) was compared to single FOV (sFOV) and one with double the single size (dFOV). In addition to advancing our understanding of visual information in mosaicing, the present study examines the advantages and limitations of a number of metrics used to evaluate performance in path integration tasks, with particular attention paid to measuring performance in identifying complex routes. The highlights of the results are summarized as follows, according to Experiments 1 through 3 respectively. 1. A novel response method for evaluating route identification performance was developed. The surmised benefits of the mFOV relative to sFOV and dFOV revealed no significant differences in performance for the relatively simple route shapes tested. Compared to the mFOV and dFOV conditions, target detection performance in the local task was found to be superior in the sFOV condition. 2. In order to appropriately quantify the observed differences in complex route selections made by the participants, a novel analysis method was developed using the Thurstonian Paired Comparisons Method. 3. To investigate the effect of display size and elevation angle (EA) in a complex route environment, a 2x3 experiment was conducted for the two spatial tasks, at a height selected from Experiment 2. Although no significant differences were found in the target detection task, contrasts in the Paired Comparisons Method results revealed that route identification performance were as hypothesised: mFOV > dFOV > sFOV for EA = 90°. Results were similar for EA = 45°, but with mFOV being no different than dFOV. As hypothesised, EA was found to have an effect on route selection performance, with a top down view performing better than an angled view for the mFOV and sFOV conditions.

Are Letter Detection and Proofreading Tasks Equivalent?

ERIC Educational Resources Information Center

Saint-Aubin, Jean; Losier, Marie-Claire; Roy, Macha; Lawrence, Mike

2015-01-01

When readers search for misspellings in a proofreading task or for a letter in a letter detection task, they are more likely to omit function words than content words. However, with misspelled words, previous findings for the letter detection task were mixed. In two experiments, the authors tested the functional equivalence of both tasks. Results…

Classification of change detection and change blindness from near-infrared spectroscopy signals

NASA Astrophysics Data System (ADS)

Tanaka, Hirokazu; Katura, Takusige

2011-08-01

Using a machine-learning classification algorithm applied to near-infrared spectroscopy (NIRS) signals, we classify a success (change detection) or a failure (change blindness) in detecting visual changes for a change-detection task. Five subjects perform a change-detection task, and their brain activities are continuously monitored. A support-vector-machine algorithm is applied to classify the change-detection and change-blindness trials, and correct classification probability of 70-90% is obtained for four subjects. Two types of temporal shapes in classification probabilities are found: one exhibiting a maximum value after the task is completed (postdictive type), and another exhibiting a maximum value during the task (predictive type). As for the postdictive type, the classification probability begins to increase immediately after the task completion and reaches its maximum in about the time scale of neuronal hemodynamic response, reflecting a subjective report of change detection. As for the predictive type, the classification probability shows an increase at the task initiation and is maximal while subjects are performing the task, predicting the task performance in detecting a change. We conclude that decoding change detection and change blindness from NIRS signal is possible and argue some future applications toward brain-machine interfaces.

Hyperoxia and Hypoxic Hypoxia Effects on Simple and Choice Reaction Times.

PubMed

Dart, Todd; Gallo, Megan; Beer, Jeremy; Fischer, Joseph; Morgan, Thomas; Pilmanis, Andrew

2017-12-01

Effects of exposure to hyperoxia (PiO2 > 105 mmHg), normoxia (PiO2 95-105 mmHg) and hypoxia (PiO2 < 95 mmHg) on simple and choice reaction performance tasks were evaluated. Ten subjects performed simple and choice reaction time tests (SRT and CRT, respectively) at ground level for 40 min (20 min normoxic, 20 min hyperoxic, randomly assigned), 3048 m (10,000 ft) for 75 min (15 min hyperoxic, 60 min hypoxic), 4572 m (15,000 ft) for 60 min (15 min hyperoxic, 45 min hypoxic), and 6096 m (20,000 ft) for 35 min (15 min hyperoxic, 20 min hypoxic). SRT and CRT tests were also conducted at ground level 1 h after normoxic rest (recovery) to assess any recovery time effect on these psychomotor tasks. Total response time (TRT) significantly increased by 15 ms to 25 ms at all three altitudes for both the SRT and CRT tasks. At and below 4572 m, the performance changes were gradual over the duration of the exposures, whereas at 6096 m these changes were immediate. After 1 h, no performance decrement was measured. There was no statistical evidence that ground-level performance on these tasks was improved in hyperoxic vs. normoxic conditions. Results suggest mild decrements in reaction time due to hypoxia may occur as low as 3048 m (10,000 ft) while hyperoxia showed no positive effect on accuracy or reaction time at ground level or higher when performing simple and choice psychomotor reaction tasks.Dart T, Gallo M, Beer J, Fischer J, Morgan T, Pilmanis A. Hyperoxia and hypoxic hypoxia effects on simple and choice reaction times. Aerosp Med Hum Perform. 2017; 88(12):1073-1080.

Sensory Gain Outperforms Efficient Readout Mechanisms in Predicting Attention-Related Improvements in Behavior

PubMed Central

Ester, Edward F.; Deering, Sean

2014-01-01

Spatial attention has been postulated to facilitate perceptual processing via several different mechanisms. For instance, attention can amplify neural responses in sensory areas (sensory gain), mediate neural variability (noise modulation), or alter the manner in which sensory signals are selectively read out by postsensory decision mechanisms (efficient readout). Even in the context of simple behavioral tasks, it is unclear how well each of these mechanisms can account for the relationship between attention-modulated changes in behavior and neural activity because few studies have systematically mapped changes between stimulus intensity, attentional focus, neural activity, and behavioral performance. Here, we used a combination of psychophysics, event-related potentials (ERPs), and quantitative modeling to explicitly link attention-related changes in perceptual sensitivity with changes in the ERP amplitudes recorded from human observers. Spatial attention led to a multiplicative increase in the amplitude of an early sensory ERP component (the P1, peaking ∼80–130 ms poststimulus) and in the amplitude of the late positive deflection component (peaking ∼230–330 ms poststimulus). A simple model based on signal detection theory demonstrates that these multiplicative gain changes were sufficient to account for attention-related improvements in perceptual sensitivity, without a need to invoke noise modulation. Moreover, combining the observed multiplicative gain with a postsensory readout mechanism resulted in a significantly poorer description of the observed behavioral data. We conclude that, at least in the context of relatively simple visual discrimination tasks, spatial attention modulates perceptual sensitivity primarily by modulating the gain of neural responses during early sensory processing PMID:25274817

The role of awareness of repetition during the development of automaticity in a dot-counting task

PubMed Central

Shadbolt, Emma

2018-01-01

This study examined whether being aware of the repetition of stimuli in a simple numerosity task could aid the development of automaticity. The numerosity task used in this study was a simple counting task. Thirty-four participants were divided into two groups. One group was instructed that the stimuli would repeat many times throughout the experiment. The results showed no significant differences in the way automatic processing developed between the groups. Similarly, there was no correlation between the point at which automatic processing developed and the point at which participants felt they benefitted from the repetition of stimuli. These results suggest that extra-trial features of a task may have no effect on the development of automaticity, a finding consistent with the instance theory of automatisation. PMID:29404220

Awareness of financial skills in dementia.

PubMed

Van Wielingen, L E; Tuokko, H A; Cramer, K; Mateer, C A; Hultsch, D F

2004-07-01

The present study examined the relations among levels of cognitive functioning, executive dysfunction, and awareness of financial management capabilities among a sample of 42 community-dwelling persons with dementia. Financial tasks on the Measure of Awareness of Financial Skills (MAFS) were dichotomized as simple or complex based on Piaget's operational levels of childhood cognitive development. Severity of global cognitive impairment and executive dysfunction were significantly related to awareness of financial abilities as measured by informant-participant discrepancy scores on the MAFS. For persons with mild and moderate/severe dementia, and persons with and without executive dysfunction, proportions of awareness within simple and complex financial task categories were tabulated. Significantly less awareness of financial abilities occurred on complex compared with simple tasks. Individuals with mild dementia were significantly less aware of abilities on complex items, whereas persons with moderate/severe dementia were less aware of abilities, regardless of task complexity. Similar patterns of awareness were observed for individuals with and without executive dysfunction. These findings support literature suggesting that deficits associated with dementia first occur for complex cognitive tasks involving inductive reasoning or decision-making in novel situations, and identify where loss of function in the financial domain may first be expected. Copyright Taylor & Francis Ltd

Beam walking can detect differences in walking balance proficiency across a range of sensorimotor abilities.

PubMed

Sawers, Andrew; Ting, Lena H

2015-02-01

The ability to quantify differences in walking balance proficiency is critical to curbing the rising health and financial costs of falls. Current laboratory-based approaches typically focus on successful recovery of balance while clinical instruments often pose little difficulty for all but the most impaired patients. Rarely do they test motor behaviors of sufficient difficulty to evoke failures in balance control limiting their ability to quantify balance proficiency. Our objective was to test whether a simple beam-walking task could quantify differences in walking balance proficiency across a range of sensorimotor abilities. Ten experts, ten novices, and five individuals with transtibial limb loss performed six walking trials across three different width beams. Walking balance proficiency was quantified as the ratio of distance walked to total possible distance. Balance proficiency was not significantly different between cohorts on the wide-beam, but clear differences between cohorts on the mid and narrow-beams were identified. Experts walked a greater distance than novices on the mid-beam (average of 3.63±0.04m verus 2.70±0.21m out of 3.66m; p=0.009), and novices walked further than amputees (1.52±0.20m; p=0.03). Amputees were unable to walk on the narrow-beam, while experts walked further (3.07±0.14m) than novices (1.55±0.26m; p=0.0005). A simple beam-walking task and an easily collected measure of distance traveled detected differences in walking balance proficiency across sensorimotor abilities. This approach provides a means to safely study and evaluate successes and failures in walking balance in the clinic or lab. It may prove useful in identifying mechanisms underlying falls versus fall recoveries. Copyright © 2015 Elsevier B.V. All rights reserved.

Neurophysiological Pharmacodynamic Measures of Groups and Individuals Extended from Simple Cognitive Tasks to More “Lifelike” Activities

PubMed Central

Gevins, Alan; Chan, Cynthia S.; Jiang, An; Sam-Vargas, Lita

2012-01-01

Objective Extend a method to track neurophysiological pharmacodynamics during repetitive cognitive testing to a more complex “lifelike” task. Methods Alcohol was used as an exemplar psychoactive substance. An equation, derived in an exploratory analysis to detect alcohol’s EEGs effects during repetitive cognitive testing, was validated in a confirmatory study on a new group whose EEGs after alcohol and placebo were recorded during working memory testing and while operating an automobile driving simulator. Results The equation recognized alcohol by combining five times beta plus theta power. It worked well (p<.0001) when applied to both tasks in the confirmatory group. The maximum EEG effect occurred 2–2.5 hours after drinking (>1hr after peak BAC) and remained at 90% at 3.5–4 hours (BAC <50% of peak). Individuals varied in the magnitude and timing of the EEG effect. Conclusion The equation tracked the EEG response to alcohol in the confirmatory study during both repetitive cognitive testing and a more complex “lifelike” task. The EEG metric was more sensitive to alcohol than several autonomic physiological measures, task performance measures or self-reports. Significance Using EEG as a biomarker to track neurophysiological pharmacodynamics during complex “lifelike” activities may prove useful for assessing how drugs affect integrated brain functioning. PMID:23194853

Impaired motor inhibition in adults who stutter - evidence from speech-free stop-signal reaction time tasks.

PubMed

Markett, Sebastian; Bleek, Benjamin; Reuter, Martin; Prüss, Holger; Richardt, Kirsten; Müller, Thilo; Yaruss, J Scott; Montag, Christian

2016-10-01

Idiopathic stuttering is a fluency disorder characterized by impairments during speech production. Deficits in the motor control circuits of the basal ganglia have been implicated in idiopathic stuttering but it is unclear how these impairments relate to the disorder. Previous work has indicated a possible deficiency in motor inhibition in children who stutter. To extend these findings to adults, we designed two experiments to probe executive motor control in people who stutter using manual reaction time tasks that do not rely on speech production. We used two versions of the stop-signal reaction time task, a measure for inhibitory motor control that has been shown to rely on the basal ganglia circuits. We show increased stop-signal reaction times in two independent samples of adults who stutter compared to age- and sex-matched control groups. Additional measures involved simple reaction time measurements and a task-switching task where no group difference was detected. Results indicate a deficiency in inhibitory motor control in people who stutter in a task that does not rely on overt speech production and cannot be explained by general deficits in executive control or speeded motor execution. This finding establishes the stop-signal reaction time as a possible target for future experimental and neuroimaging studies on fluency disorders and is a further step towards unraveling the contribution of motor control deficits to idiopathic stuttering. Copyright © 2016 Elsevier Ltd. All rights reserved.

An electrophysiological study of the impact of a Forward Collision Warning System in a simulator driving task.

PubMed

Bueno, Mercedes; Fabrigoule, Colette; Deleurence, Philippe; Ndiaye, Daniel; Fort, Alexandra

2012-08-27

Driver distraction has been identified as the most important contributing factor in rear-end collisions. In this context, Forward Collision Warning Systems (FCWS) have been developed specifically to warn drivers of potential rear-end collisions. The main objective of this work is to evaluate the impact of a surrogate FCWS and of its reliability according to the driver's attentional state by recording both behavioral and electrophysiological data. Participants drove following a lead motorcycle in a simplified simulator with or without a warning system which gave forewarning of the preceding vehicle braking. Participants had to perform this driving task either alone (simple task) or simultaneously with a secondary cognitive task (dual task). Behavioral and electrophysiological data contributed to revealing a positive effect of the warning system. Participants were faster in detecting the brake light when the system was perfect or imperfect, and the time and attentional resources allocation required for processing the target at higher cognitive level were reduced when the system was completely reliable. When both tasks were performed simultaneously, warning effectiveness was considerably affected at both performance and neural levels; however, the analysis of the brain activity revealed fewer differences between distracted and undistracted drivers when using the warning system. These results show that electrophysiological data could be a valuable tool to complement behavioral data and to have a better understanding of how these systems impact the driver. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of attention alternation on movement-related cortical potentials in healthy individuals and stroke patients.

PubMed

Aliakbaryhosseinabadi, Susan; Kostic, Vladimir; Pavlovic, Aleksandra; Radovanovic, Sasa; Nlandu Kamavuako, Ernest; Jiang, Ning; Petrini, Laura; Dremstrup, Kim; Farina, Dario; Mrachacz-Kersting, Natalie

2017-01-01

In this study, we analyzed the influence of artificially imposed attention variations using the auditory oddball paradigm on the cortical activity associated to motor preparation/execution. EEG signals from Cz and its surrounding channels were recorded during three sets of ankle dorsiflexion movements. Each set was interspersed with either a complex or a simple auditory oddball task for healthy participants and a complex auditory oddball task for stroke patients. The amplitude of the movement-related cortical potentials (MRCPs) decreased with the complex oddball paradigm, while MRCP variability increased. Both oddball paradigms increased the detection latency significantly (p<0.05) and the complex paradigm decreased the true positive rate (TPR) (p=0.04). In patients, the negativity of the MRCP decreased while pre-phase variability increased, and the detection latency and accuracy deteriorated with attention diversion. Attention diversion has a significant influence on MRCP features and detection parameters, although these changes were counteracted by the application of the laplacian method. Brain-computer interfaces for neuromodulation that use the MRCP as the control signal are robust to changes in attention. However, attention must be monitored since it plays a key role in plasticity induction. Here we demonstrate that this can be achieved using the single channel Cz. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A Developmental and Cognitivist Approach to a Perceptuo-Motor Task.

ERIC Educational Resources Information Center

Zanone, P. G.; Hauert, C. A.

Discussed are data concerning a simple visuomotor tracking task, especially the expectations and cognitive representations involved in performing such a task. The task consisted in tracking the horizontal displacement of a target spot on the screen by appropriate forearm rotations. Each subject participated in two sessions: first, at a .8 Hz…

Variations in Articulatory Movement with Changes in Speech Task.

ERIC Educational Resources Information Center

Tasko, Stephen M.; McClean, Michael D.

2004-01-01

Studies of normal and disordered articulatory movement often rely on the use of short, simple speech tasks. However, the severity of speech disorders can be observed to vary markedly with task. Understanding task-related variations in articulatory kinematic behavior may allow for an improved understanding of normal and disordered speech motor…

Child–Adult Differences in Using Dual-Task Paradigms to Measure Listening Effort

PubMed Central

Charles, Lauren M.; Ricketts, Todd A.

2017-01-01

Purpose The purpose of the project was to investigate the effects modifying the secondary task in a dual-task paradigm to measure objective listening effort. To be specific, the complexity and depth of processing were increased relative to a simple secondary task. Method Three dual-task paradigms were developed for school-age children. The primary task was word recognition. The secondary task was a physical response to a visual probe (simple task), a physical response to a complex probe (increased complexity), or word categorization (increased depth of processing). Sixteen adults (22–32 years, M = 25.4) and 22 children (9–17 years, M = 13.2) were tested using the 3 paradigms in quiet and noise. Results For both groups, manipulations of the secondary task did not affect word recognition performance. For adults, increasing depth of processing increased the calculated effect of noise; however, for children, results with the deep secondary task were the least stable. Conclusions Manipulations of the secondary task differentially affected adults and children. Consistent with previous findings, increased depth of processing enhanced paradigm sensitivity for adults. However, younger participants were more likely to demonstrate the expected effects of noise on listening effort using a secondary task that did not require deep processing. PMID:28346816

Comparison of the Working Memory Load in N-Back and Working Memory Span Tasks by Means of EEG Frequency Band Power and P300 Amplitude

PubMed Central

Scharinger, Christian; Soutschek, Alexander; Schubert, Torsten; Gerjets, Peter

2017-01-01

According to theoretical accounts, both, N-back and complex span tasks mainly require working memory (WM) processing. In contrast, simple span tasks conceptually mainly require WM storage. Thus, conceptually, an N-back task and a complex span task share more commonalities as compared to a simple span task. In the current study, we compared an N-back task, a complex operation span task (Ospan), and a simple digit span task (Dspan) by means of typical WM load-related measures of the Electroencephalogram (EEG) like the parietal alpha and beta frequency band power, the frontal theta frequency band power, and the P300 amplitude, to examine whether these tasks would show commonalities or differences in WM processing-load. We expected that increasing WM-load would generally lead to a decreased alpha and beta frequency band power, an increased theta frequency band power, and a decreased P300 amplitude. Yet, based on the conceptual considerations, we hypothesized that the outcomes of these measures would be more comparable between the N-back and the Ospan as compared to the Dspan. Our hypotheses were partly confirmed. The N-back and the Ospan showed timely more prolonged alpha frequency band power effects as compared to the Dspan. This might indicate higher demands on WM processing in the former two tasks. The theta frequency band power and the P300 amplitude were most pronounced in the N-back task as compared to both span tasks. This might indicate specific demands on cognitive control in the N-back task. Additionally, we observed that behavioral performance measures correlated with changes in EEG alpha power of the N-back and the Ospan, yet not of the Dspan. Taken together, the hypothesized conceptual commonalities between the N-back task and the Ospan (and, for the Dspan, differences) were only partly confirmed by the electrophysiological WM load-related measures, indicating a potential need for reconsidering the theoretical accounts on WM tasks and the value of a closer link to electrophysiological research herein. PMID:28179880

Comparison of the Working Memory Load in N-Back and Working Memory Span Tasks by Means of EEG Frequency Band Power and P300 Amplitude.

PubMed

Scharinger, Christian; Soutschek, Alexander; Schubert, Torsten; Gerjets, Peter

2017-01-01

According to theoretical accounts, both, N -back and complex span tasks mainly require working memory (WM) processing. In contrast, simple span tasks conceptually mainly require WM storage. Thus, conceptually, an N -back task and a complex span task share more commonalities as compared to a simple span task. In the current study, we compared an N -back task, a complex operation span task (Ospan), and a simple digit span task (Dspan) by means of typical WM load-related measures of the Electroencephalogram (EEG) like the parietal alpha and beta frequency band power, the frontal theta frequency band power, and the P300 amplitude, to examine whether these tasks would show commonalities or differences in WM processing-load. We expected that increasing WM-load would generally lead to a decreased alpha and beta frequency band power, an increased theta frequency band power, and a decreased P300 amplitude. Yet, based on the conceptual considerations, we hypothesized that the outcomes of these measures would be more comparable between the N -back and the Ospan as compared to the Dspan. Our hypotheses were partly confirmed. The N -back and the Ospan showed timely more prolonged alpha frequency band power effects as compared to the Dspan. This might indicate higher demands on WM processing in the former two tasks. The theta frequency band power and the P300 amplitude were most pronounced in the N -back task as compared to both span tasks. This might indicate specific demands on cognitive control in the N -back task. Additionally, we observed that behavioral performance measures correlated with changes in EEG alpha power of the N -back and the Ospan, yet not of the Dspan. Taken together, the hypothesized conceptual commonalities between the N -back task and the Ospan (and, for the Dspan, differences) were only partly confirmed by the electrophysiological WM load-related measures, indicating a potential need for reconsidering the theoretical accounts on WM tasks and the value of a closer link to electrophysiological research herein.

A Real-Time Lift Detection Strategy for a Hip Exoskeleton

PubMed Central

Chen, Baojun; Grazi, Lorenzo; Lanotte, Francesco; Vitiello, Nicola; Crea, Simona

2018-01-01

Repetitive lifting of heavy loads increases the risk of back pain and even lumbar vertebral injuries to workers. Active exoskeletons can help workers lift loads by providing power assistance, and therefore reduce the moment and force applied on L5/S1 joint of human body when performing lifting tasks. However, most existing active exoskeletons for lifting assistance are unable to automatically detect user's lift movement, which limits the wide application of active exoskeletons in factories. In this paper, we propose a simple but effective lift detection strategy for exoskeleton control. This strategy uses only exoskeleton integrated sensors, without any extra sensors to capture human motion intentions. This makes the lift detection system more practical for applications in manufacturing environments. Seven healthy subjects participated in this research. Three different sessions were carried out, two for training and one for testing the algorithm. In the two training sessions, subjects were asked to wear a hip exoskeleton, controlled in transparent mode, and perform repetitive lifting and a locomotion circuit; lifting was executed with different techniques. The collected data were used to train the lift detection model. In the testing session, the exoskeleton was controlled in order to deliver torque to assist the lifting action, based on the lift detection made by the trained algorithm. The across-subject average accuracy of lift detection during online test was 97.97 ± 1.39% with subject-dependent model. Offline, the algorithm was trained with data acquired from all subjects to verify its performance for subject-independent detection, and an accuracy of 97.48 ± 1.53% was achieved. In addition, timeliness of the algorithm was quantitatively evaluated and the time delay was <160 ms across different lifting speeds. Surface electromyography was also measured to assess the efficacy of the exoskeleton in assisting subjects in performing load lifting tasks. These results validate the promise of applying the proposed lift detection strategy for exoskeleton control aiming at lift assistance. PMID:29706881

A Real-Time Lift Detection Strategy for a Hip Exoskeleton.

PubMed

Chen, Baojun; Grazi, Lorenzo; Lanotte, Francesco; Vitiello, Nicola; Crea, Simona

2018-01-01

Repetitive lifting of heavy loads increases the risk of back pain and even lumbar vertebral injuries to workers. Active exoskeletons can help workers lift loads by providing power assistance, and therefore reduce the moment and force applied on L5/S1 joint of human body when performing lifting tasks. However, most existing active exoskeletons for lifting assistance are unable to automatically detect user's lift movement, which limits the wide application of active exoskeletons in factories. In this paper, we propose a simple but effective lift detection strategy for exoskeleton control. This strategy uses only exoskeleton integrated sensors, without any extra sensors to capture human motion intentions. This makes the lift detection system more practical for applications in manufacturing environments. Seven healthy subjects participated in this research. Three different sessions were carried out, two for training and one for testing the algorithm. In the two training sessions, subjects were asked to wear a hip exoskeleton, controlled in transparent mode, and perform repetitive lifting and a locomotion circuit; lifting was executed with different techniques. The collected data were used to train the lift detection model. In the testing session, the exoskeleton was controlled in order to deliver torque to assist the lifting action, based on the lift detection made by the trained algorithm. The across-subject average accuracy of lift detection during online test was 97.97 ± 1.39% with subject-dependent model. Offline, the algorithm was trained with data acquired from all subjects to verify its performance for subject-independent detection, and an accuracy of 97.48 ± 1.53% was achieved. In addition, timeliness of the algorithm was quantitatively evaluated and the time delay was <160 ms across different lifting speeds. Surface electromyography was also measured to assess the efficacy of the exoskeleton in assisting subjects in performing load lifting tasks. These results validate the promise of applying the proposed lift detection strategy for exoskeleton control aiming at lift assistance.

Single-trial classification of motor imagery differing in task complexity: a functional near-infrared spectroscopy study

PubMed Central

2011-01-01

Background For brain computer interfaces (BCIs), which may be valuable in neurorehabilitation, brain signals derived from mental activation can be monitored by non-invasive methods, such as functional near-infrared spectroscopy (fNIRS). Single-trial classification is important for this purpose and this was the aim of the presented study. In particular, we aimed to investigate a combined approach: 1) offline single-trial classification of brain signals derived from a novel wireless fNIRS instrument; 2) to use motor imagery (MI) as mental task thereby discriminating between MI signals in response to different tasks complexities, i.e. simple and complex MI tasks. Methods 12 subjects were asked to imagine either a simple finger-tapping task using their right thumb or a complex sequential finger-tapping task using all fingers of their right hand. fNIRS was recorded over secondary motor areas of the contralateral hemisphere. Using Fisher's linear discriminant analysis (FLDA) and cross validation, we selected for each subject a best-performing feature combination consisting of 1) one out of three channel, 2) an analysis time interval ranging from 5-15 s after stimulation onset and 3) up to four Δ[O2Hb] signal features (Δ[O2Hb] mean signal amplitudes, variance, skewness and kurtosis). Results The results of our single-trial classification showed that using the simple combination set of channels, time intervals and up to four Δ[O2Hb] signal features comprising Δ[O2Hb] mean signal amplitudes, variance, skewness and kurtosis, it was possible to discriminate single-trials of MI tasks differing in complexity, i.e. simple versus complex tasks (inter-task paired t-test p ≤ 0.001), over secondary motor areas with an average classification accuracy of 81%. Conclusions Although the classification accuracies look promising they are nevertheless subject of considerable subject-to-subject variability. In the discussion we address each of these aspects, their limitations for future approaches in single-trial classification and their relevance for neurorehabilitation. PMID:21682906

Orientations for the successful categorization of facial expressions and their link with facial features.

PubMed

Duncan, Justin; Gosselin, Frédéric; Cobarro, Charlène; Dugas, Gabrielle; Blais, Caroline; Fiset, Daniel

2017-12-01

Horizontal information was recently suggested to be crucial for face identification. In the present paper, we expand on this finding and investigate the role of orientations for all the basic facial expressions and neutrality. To this end, we developed orientation bubbles to quantify utilization of the orientation spectrum by the visual system in a facial expression categorization task. We first validated the procedure in Experiment 1 with a simple plaid-detection task. In Experiment 2, we used orientation bubbles to reveal the diagnostic-i.e., task relevant-orientations for the basic facial expressions and neutrality. Overall, we found that horizontal information was highly diagnostic for expressions-surprise excepted. We also found that utilization of horizontal information strongly predicted performance level in this task. Despite the recent surge of research on horizontals, the link with local features remains unexplored. We were thus also interested in investigating this link. In Experiment 3, location bubbles were used to reveal the diagnostic features for the basic facial expressions. Crucially, Experiments 2 and 3 were run in parallel on the same participants, in an interleaved fashion. This way, we were able to correlate individual orientation and local diagnostic profiles. Our results indicate that individual differences in horizontal tuning are best predicted by utilization of the eyes.

Human versus automation in responding to failures: an expected-value analysis

NASA Technical Reports Server (NTRS)

Sheridan, T. B.; Parasuraman, R.

2000-01-01

A simple analytical criterion is provided for deciding whether a human or automation is best for a failure detection task. The method is based on expected-value decision theory in much the same way as is signal detection. It requires specification of the probabilities of misses (false negatives) and false alarms (false positives) for both human and automation being considered, as well as factors independent of the choice--namely, costs and benefits of incorrect and correct decisions as well as the prior probability of failure. The method can also serve as a basis for comparing different modes of automation. Some limiting cases of application are discussed, as are some decision criteria other than expected value. Actual or potential applications include the design and evaluation of any system in which either humans or automation are being considered.

Variations on a theme by chopin: relations between perception and production of timing in music.

PubMed

Repp, B H

1998-06-01

A note interonset interval (IOI) increment in mechanically timed music is more difficult to detect where expressive lengthening typically occurs in artistic performance. Experiment 1 showed this in an excerpt from a Chopin etude and extended the task to IOI decrement detection. A simple measure of variation in perceptual bias was derived that correlated highly with the average timing pattern of pianists' performances, more so than with acoustic surface properties of the music. Similar results, but decreasing correlations, were obtained in each of four subsequent experiments in which the music was simplified in stages. Although local psychoacoustic effects on time perception cannot be ruled out completely, the results suggest that musical structure (melodic-rhythmic grouping in particular) has temporal implications that are reflected not only in musicians' motor behavior but also in listeners' time-keeping abilities.

Event detection and localization for small mobile robots using reservoir computing.

PubMed

Antonelo, E A; Schrauwen, B; Stroobandt, D

2008-08-01

Reservoir Computing (RC) techniques use a fixed (usually randomly created) recurrent neural network, or more generally any dynamic system, which operates at the edge of stability, where only a linear static readout output layer is trained by standard linear regression methods. In this work, RC is used for detecting complex events in autonomous robot navigation. This can be extended to robot localization tasks which are solely based on a few low-range, high-noise sensory data. The robot thus builds an implicit map of the environment (after learning) that is used for efficient localization by simply processing the input stream of distance sensors. These techniques are demonstrated in both a simple simulation environment and in the physically realistic Webots simulation of the commercially available e-puck robot, using several complex and even dynamic environments.

Normal aging affects movement execution but not visual motion working memory and decision-making delay during cue-dependent memory-based smooth-pursuit.

PubMed

Fukushima, Kikuro; Barnes, Graham R; Ito, Norie; Olley, Peter M; Warabi, Tateo

2014-07-01

Aging affects virtually all functions including sensory/motor and cognitive activities. While retinal image motion is the primary input for smooth-pursuit, its efficiency/accuracy depends on cognitive processes. Elderly subjects exhibit gain decrease during initial and steady-state pursuit, but reports on latencies are conflicting. Using a cue-dependent memory-based smooth-pursuit task, we identified important extra-retinal mechanisms for initial pursuit in young adults including cue information priming and extra-retinal drive components (Ito et al. in Exp Brain Res 229:23-35, 2013). We examined aging effects on parameters for smooth-pursuit using the same tasks. Elderly subjects were tested during three task conditions as previously described: memory-based pursuit, simple ramp-pursuit just to follow motion of a single spot, and popping-out of the correct spot during memory-based pursuit to enhance retinal image motion. Simple ramp-pursuit was used as a task that did not require visual motion working memory. To clarify aging effects, we then compared the results with the previous young subject data. During memory-based pursuit, elderly subjects exhibited normal working memory of cue information. Most movement-parameters including pursuit latencies differed significantly between memory-based pursuit and simple ramp-pursuit and also between young and elderly subjects. Popping-out of the correct spot motion was ineffective for enhancing initial pursuit in elderly subjects. However, the latency difference between memory-based pursuit and simple ramp-pursuit in individual subjects, which includes decision-making delay in the memory task, was similar between the two groups. Our results suggest that smooth-pursuit latencies depend on task conditions and that, although the extra-retinal mechanisms were functional for initial pursuit in elderly subjects, they were less effective.

Frontal lobe functioning during a simple response conflict task in first-episode psychosis and its relationship to treatment response.

PubMed

Shafritz, Keith M; Ikuta, Toshikazu; Greene, Allison; Robinson, Delbert G; Gallego, Juan; Lencz, Todd; DeRosse, Pamela; Kingsley, Peter B; Szeszko, Philip R

2018-05-09

Prior functional magnetic resonance imaging (fMRI) studies have investigated the neural mechanisms underlying cognitive control in patients with psychosis with findings of both hypo- and hyperfrontality. One factor that may contribute to inconsistent findings is the use of complex and polyfactorial tasks to investigate frontal lobe functioning. In the current study we employed a simple response conflict task during fMRI to examine differences in brain activation between patients experiencing their first-episode of psychosis (n = 33) and age- and sex-matched healthy volunteers (n = 33). We further investigated whether baseline brain activation among patients predicted changes in symptom severity and treatment response following 12 weeks of controlled antipsychotic treatment. During the task subjects were instructed to press a response button on the same side or opposite side of a circle that appeared on either side of a central fixation point. Imaging data revealed that for the contrast of opposite-side vs. same-side, patients showed significantly greater activation compared with healthy volunteers in the anterior cingulate cortex and intraparietal sulcus. Among patients, greater baseline anterior cingulate cortex, temporal-parietal junction, and superior temporal cortex activation predicted greater symptom reduction and therapeutic response following treatment. All findings remained significant after covarying for task performance. Intact performance on this relatively parsimonious task was associated with frontal hyperactivity suggesting the need for patients to utilize greater neural resources to achieve task performance comparable to healthy individuals. Moreover, frontal hyperactivity observed using a simple fMRI task may provide a biomarker for predicting treatment response in first-episode psychosis.

Cognitive Load Differentially Impacts Response Control in Girls and Boys with ADHD

PubMed Central

Mostofsky, Stewart H.; Rosch, Keri S.

2015-01-01

Children with attention-deficit hyperactivity disorder (ADHD) consistently show impaired response control, including deficits in response inhibition and increased intrasubject variability (ISV) compared to typically-developing (TD) children. However, significantly less research has examined factors that may influence response control in individuals with ADHD, such as task or participant characteristics. The current study extends the literature by examining the impact of increasing cognitive demands on response control in a large sample of 81children with ADHD (40 girls) and 100 TD children (47 girls), ages 8–12 years. Participants completed a simple Go/No-Go (GNG) task with minimal cognitive demands, and a complex GNG task with increased cognitive load. Results showed that increasing cognitive load differentially impacted response control (commission error rate and tau, an ex-Gaussian measure of ISV) for girls, but not boys, with ADHD compared to same-sex TD children. Specifically, a sexually dimorphic pattern emerged such that boys with ADHD demonstrated higher commission error rate and tau on both the simple and complex GNG tasks as compared to TD boys, whereas girls with ADHD did not differ from TD girls on the simple GNG task, but showed higher commission error rate and tau on the complex GNG task. These findings suggest that task complexity influences response control in children with ADHD in a sexually dimorphic manner. The findings have substantive implications for the pathophysiology of ADHD in boys versus girls with ADHD. PMID:25624066

A Test of Canine Olfactory Capacity: Comparing Various Dog Breeds and Wolves in a Natural Detection Task

PubMed Central

Polgár, Zita; Kinnunen, Mari; Újváry, Dóra; Miklósi, Ádám; Gácsi, Márta

2016-01-01

Many dog breeds are bred specifically for increased performance in scent-based tasks. Whether dogs bred for this purpose have higher olfactory capacities than other dogs, or even wolves with whom they share a common ancestor, has not yet been studied. Indeed, there is no standard test for assessing canine olfactory ability. This study aimed to create a simple procedure that requires no pre-training and to use it to measure differences in olfactory capacity across four groups of canines: (1) dog breeds that have been selected for their scenting ability; (2) dog breeds that have been bred for other purposes; (3) dog breeds with exaggerated short-nosed features; and (4) hand-reared grey wolves. The procedure involved baiting a container with raw turkey meat and placing it under one of four identical ceramic pots. Subjects were led along the row of pots and were tasked with determining by olfaction alone which of them contained the bait. There were five levels of increasing difficulty determined by the number of holes on the container’s lid. A subsample of both dogs and wolves was retested to assess reliability. The results showed that breeds selected for scent work were better than both short-nosed and non-scent breeds. In the most difficult level, wolves and scenting breeds performed better than chance, while non-scenting and short-nosed breeds did not. In the retested samples wolves improved their success; however, dogs showed no change in their performances indicating that a single test may be reliable enough to assess their capacity. Overall, we revealed measurable differences between dog breeds in their olfactory abilities and suggest that the Natural Detection Task is a good foundation for developing an efficient way of quantifying them. PMID:27152412

A Test of Canine Olfactory Capacity: Comparing Various Dog Breeds and Wolves in a Natural Detection Task.

PubMed

Polgár, Zita; Kinnunen, Mari; Újváry, Dóra; Miklósi, Ádám; Gácsi, Márta

2016-01-01

Many dog breeds are bred specifically for increased performance in scent-based tasks. Whether dogs bred for this purpose have higher olfactory capacities than other dogs, or even wolves with whom they share a common ancestor, has not yet been studied. Indeed, there is no standard test for assessing canine olfactory ability. This study aimed to create a simple procedure that requires no pre-training and to use it to measure differences in olfactory capacity across four groups of canines: (1) dog breeds that have been selected for their scenting ability; (2) dog breeds that have been bred for other purposes; (3) dog breeds with exaggerated short-nosed features; and (4) hand-reared grey wolves. The procedure involved baiting a container with raw turkey meat and placing it under one of four identical ceramic pots. Subjects were led along the row of pots and were tasked with determining by olfaction alone which of them contained the bait. There were five levels of increasing difficulty determined by the number of holes on the container's lid. A subsample of both dogs and wolves was retested to assess reliability. The results showed that breeds selected for scent work were better than both short-nosed and non-scent breeds. In the most difficult level, wolves and scenting breeds performed better than chance, while non-scenting and short-nosed breeds did not. In the retested samples wolves improved their success; however, dogs showed no change in their performances indicating that a single test may be reliable enough to assess their capacity. Overall, we revealed measurable differences between dog breeds in their olfactory abilities and suggest that the Natural Detection Task is a good foundation for developing an efficient way of quantifying them.

Representation of limb kinematics in Purkinje cell simple spike discharge is conserved across multiple tasks

PubMed Central

Hewitt, Angela L.; Popa, Laurentiu S.; Pasalar, Siavash; Hendrix, Claudia M.

2011-01-01

Encoding of movement kinematics in Purkinje cell simple spike discharge has important implications for hypotheses of cerebellar cortical function. Several outstanding questions remain regarding representation of these kinematic signals. It is uncertain whether kinematic encoding occurs in unpredictable, feedback-dependent tasks or kinematic signals are conserved across tasks. Additionally, there is a need to understand the signals encoded in the instantaneous discharge of single cells without averaging across trials or time. To address these questions, this study recorded Purkinje cell firing in monkeys trained to perform a manual random tracking task in addition to circular tracking and center-out reach. Random tracking provides for extensive coverage of kinematic workspaces. Direction and speed errors are significantly greater during random than circular tracking. Cross-correlation analyses comparing hand and target velocity profiles show that hand velocity lags target velocity during random tracking. Correlations between simple spike firing from 120 Purkinje cells and hand position, velocity, and speed were evaluated with linear regression models including a time constant, τ, as a measure of the firing lead/lag relative to the kinematic parameters. Across the population, velocity accounts for the majority of simple spike firing variability (63 ± 30% of Radj2), followed by position (28 ± 24% of Radj2) and speed (11 ± 19% of Radj2). Simple spike firing often leads hand kinematics. Comparison of regression models based on averaged vs. nonaveraged firing and kinematics reveals lower Radj2 values for nonaveraged data; however, regression coefficients and τ values are highly similar. Finally, for most cells, model coefficients generated from random tracking accurately estimate simple spike firing in either circular tracking or center-out reach. These findings imply that the cerebellum controls movement kinematics, consistent with a forward internal model that predicts upcoming limb kinematics. PMID:21795616

Stimulus ambiguity elicits response conflict.

PubMed

Szmalec, Arnaud; Verbruggen, Frederick; Vandierendonck, André; De Baene, Wouter; Verguts, Tom; Notebaert, Wim

2008-04-18

Conflict monitoring theory [M.M. Botvinick, T. Braver, D. Barch, C. Carter, J.D. Cohen, Conflict monitoring and cognitive control, Psychol. Rev. 108 (2001) 625-652] assumes that perceptual ambiguity among choice stimuli elicits response conflict in choice reaction. It hence predicts that response conflict is also involved in elementary variants of choice reaction time (RT) tasks, i.e., those variants that, by contrast with the Stroop task or the Go/No-Go task for instance, are rarely associated with cognitive control. In order to test this prediction, an experiment was designed in which participants performed a simple RT task and a regular between-hand 2-choice RT task under three different levels of stimulus ambiguity. The data show that response conflict, as measured by the N2 component of the event-related brain potential (ERP), was elicited in the 2-choice RT task but not in the simple RT task and that the degree of response conflict in the 2-choice RT task was a function of stimulus ambiguity. These results show that response conflict is also present in a regular choice RT task which is traditionally not considered to be a measure of cognitive conflict.

A new approach to global control of redundant manipulators

NASA Technical Reports Server (NTRS)

Seraji, Homayoun

1989-01-01

A new and simple approach to configuration control of redundant manipulators is presented. In this approach, the redundancy is utilized to control the manipulator configuration directly in task space, where the task will be performed. A number of kinematic functions are defined to reflect the desirable configuration that will be achieved for a given end-effector position. The user-defined kinematic functions and the end-effector Cartesian coordinates are combined to form a set of task-related configuration variables as generalized coordinates for the manipulator. An adaptive scheme is then utilized to globally control the configuration variables so as to achieve tracking of some desired reference trajectories. This accomplishes the basic task of desired end-effector motion, while utilizing the redundancy to achieve any additional task through the desired time variation of the kinematic functions. The control law is simple and computationally very fast, and does not require the complex manipulator dynamic model.

Inter-hemispheric interaction facilitates face processing.

PubMed

Compton, Rebecca J

2002-01-01

Many recent studies have revealed that interaction between the left and right cerebral hemispheres can aid in task performance, but these studies have tended to examine perception of simple stimuli such as letters, digits or simple shapes, which may have limited naturalistic validity. The present study extends these prior findings to a more naturalistic face perception task. Matching tasks required subjects to indicate when a target face matched one of two probe faces. Matches could be either across-field, requiring inter-hemispheric interaction, or within-field, not requiring inter-hemispheric interaction. Subjects indicated when faces matched in emotional expression (Experiment 1; n=32) or in character identity (Experiment 2; n=32). In both experiments, across-field performance was significantly better than within-field performance, supporting the primary hypothesis. Further, this advantage was greater for the more difficult character identity task. Results offer qualified support for the hypothesis that inter-hemispheric interaction is especially advantageous as task demands increase.

The Impact of Communication Mode and Task Complexity on Small Group Performance and Member Satisfaction.

ERIC Educational Resources Information Center

Carey, Jane M.; Kacmar, Charles, J.

1997-01-01

It is often presumed that software technology will increase group productivity, but this may not be the case. Examines the impact of technology on time-to-complete-task, member satisfaction, perceived information load, number of contributing transactions, and task complexity. Three appendices provide examples of complex and simple tasks and the…

Task as a Heuristic for Understanding Student Learning and Motivation.

ERIC Educational Resources Information Center

Blumenfeld, Phyllis C.; And Others

1987-01-01

Describes the cognitive characteristics and procedural "forms" associated with common school learning tasks. Illustrates how variations in these can affect student motivation and learning. Concludes that simple task content and unvaried procedures tend to result in limited thinkers and alienated workers. (JDH)

Reliability of a Shuttle reaction timer

NASA Technical Reports Server (NTRS)

Hays, Russell D.; Mazzocca, Augustus D.; Rashid, Michael; Siconolfi, Steven F.

1992-01-01

Reaction, movement, and task times refer to the times needed to initially respond to a stimulus, make the specific movement, and complete the entire task. This study evaluated the reliability of a simple reaction timer designed to mimic a Space Shuttle task (turning on an overhead switch).

Automation effects in a multiloop manual control system

NASA Technical Reports Server (NTRS)

Hess, R. A.; Mcnally, B. D.

1986-01-01

An experimental and analytical study was undertaken to investigate human interaction with a simple multiloop manual control system in which the human's activity was systematically varied by changing the level of automation. The system simulated was the longitudinal dynamics of a hovering helicopter. The automation-systems-stabilized vehicle responses from attitude to velocity to position and also provided for display automation in the form of a flight director. The control-loop structure resulting from the task definition can be considered a simple stereotype of a hierarchical control system. The experimental study was complemented by an analytical modeling effort which utilized simple crossover models of the human operator. It was shown that such models can be extended to the description of multiloop tasks involving preview and precognitive human operator behavior. The existence of time optimal manual control behavior was established for these tasks and the role which internal models may play in establishing human-machine performance was discussed.

Effects of platooning on signal-detection performance, workload, and stress: A driving simulator study.

PubMed

Heikoop, Daniël D; de Winter, Joost C F; van Arem, Bart; Stanton, Neville A

2017-04-01

Platooning, whereby automated vehicles travel closely together in a group, is attractive in terms of safety and efficiency. However, concerns exist about the psychological state of the platooning driver, who is exempted from direct control, yet remains responsible for monitoring the outside environment to detect potential threats. By means of a driving simulator experiment, we investigated the effects on recorded and self-reported measures of workload and stress for three task-instruction conditions: (1) No Task, in which participants had to monitor the road, (2) Voluntary Task, in which participants could do whatever they wanted, and (3) Detection Task, in which participants had to detect red cars. Twenty-two participants performed three 40-min runs in a constant-speed platoon, one condition per run in counterbalanced order. Contrary to some classic literature suggesting that humans are poor monitors, in the Detection Task condition participants attained a high mean detection rate (94.7%) and a low mean false alarm rate (0.8%). Results of the Dundee Stress State Questionnaire indicated that automated platooning was less distressing in the Voluntary Task than in the Detection Task and No Task conditions. In terms of heart rate variability, the Voluntary Task condition yielded a lower power in the low-frequency range relative to the high-frequency range (LF/HF ratio) than the Detection Task condition. Moreover, a strong time-on-task effect was found, whereby the mean heart rate dropped from the first to the third run. In conclusion, participants are able to remain attentive for a prolonged platooning drive, and the type of monitoring task has effects on the driver's psychological state. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thresholds of Auditory-Motor Coupling Measured with a Simple Task in Musicians and Non-Musicians: Was the Sound Simultaneous to the Key Press?

PubMed Central

van Vugt, Floris T.; Tillmann, Barbara

2014-01-01

The human brain is able to predict the sensory effects of its actions. But how precise are these predictions? The present research proposes a tool to measure thresholds between a simple action (keystroke) and a resulting sound. On each trial, participants were required to press a key. Upon each keystroke, a woodblock sound was presented. In some trials, the sound came immediately with the downward keystroke; at other times, it was delayed by a varying amount of time. Participants were asked to verbally report whether the sound came immediately or was delayed. Participants' delay detection thresholds (in msec) were measured with a staircase-like procedure. We hypothesised that musicians would have a lower threshold than non-musicians. Comparing pianists and brass players, we furthermore hypothesised that, as a result of a sharper attack of the timbre of their instrument, pianists might have lower thresholds than brass players. Our results show that non-musicians exhibited higher thresholds for delay detection (180±104 ms) than the two groups of musicians (102±65 ms), but there were no differences between pianists and brass players. The variance in delay detection thresholds could be explained by variance in sensorimotor synchronisation capacities as well as variance in a purely auditory temporal irregularity detection measure. This suggests that the brain's capacity to generate temporal predictions of sensory consequences can be decomposed into general temporal prediction capacities together with auditory-motor coupling. These findings indicate that the brain has a relatively large window of integration within which an action and its resulting effect are judged as simultaneous. Furthermore, musical expertise may narrow this window down, potentially due to a more refined temporal prediction. This novel paradigm provides a simple test to estimate the temporal precision of auditory-motor action-effect coupling, and the paradigm can readily be incorporated in studies investigating both healthy and patient populations. PMID:24498299

Towards a model of temporal attention for on-line learning in a mobile robot

NASA Astrophysics Data System (ADS)

Marom, Yuval; Hayes, Gillian

2001-06-01

We present a simple attention system, capable of bottom-up signal detection adaptive to subjective internal needs. The system is used by a robotic agent, learning to perform phototaxis and obstacle avoidance by following a teacher agent around a simulated environment, and deciding when to form associations between perceived information and imitated actions. We refer to this kind of decision-making as on-line temporal attention. The main role of the attention system is perception of change; the system is regulated through feedback about cognitive effort. We show how different levels of effort affect both the ability to learn a task, and to execute it.

Contact sensing from force measurements

NASA Technical Reports Server (NTRS)

Bicchi, Antonio; Salisbury, J. K.; Brock, David L.

1993-01-01

This article addresses contact sensing (i.e., the problem of resolving the location of a contact, the force at the interface, and the moment about the contact normals). Called 'intrinsic' contact sensing for the use of internal force and torque measurements, this method allows for practical devices that provide simple, relevant contact information in practical robotic applications. Such sensors have been used in conjunction with robot hands to identify objects, determine surface friction, detect slip, augment grasp stability, measure object mass, probe surfaces, and control collision and for a variety of other useful tasks. This article describes the theoretical basis for their operation and provides a framework for future device design.

Reliability of a novel serious game using dual-task gait profiles to early characterize aMCI

PubMed Central

Tarnanas, Ioannis; Papagiannopoulos, Sotirios; Kazis, Dimitris; Wiederhold, Mark; Widerhold, Brenda; Tsolaki, Magda

2015-01-01

Background: As the population of older adults is growing, the interest in a simple way to detect characterize amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimer’s disease (AD), is becoming increasingly important. Serious game (SG) -based cognitive and motor performance profiles while performing everyday activities and dual-task walking (DTW) “motor signatures” are two very promising markers that can be detected in predementia states. We aim to compare the consistency, or conformity, of measurements made by a custom SG with DTW (NAV), a SG without DTW (DOT), neuropsychological measures and genotyping as markers for early detection of aMCI. Methods: The study population included three groups: early AD (n = 86), aMCI (n = 65), and healthy control subjects (n = 76), who completed the custom SG tasks in three separate sessions over a 3-month period. Outcome measures were neuropsychological data across-domain and within-domain intra-individual variability (IIV) and DOT and NAV latency-based and accuracy-based IIV. IIV reflects a transient, within-person change in behavioral performance, either during different cognitive domains (across-domain) or within the same domain (within-domain). Test–retest reliability of the DOT and NAV markers were assessed using an intraclass correlation (ICC) analysis. Results: Results indicated that performance data, such as the NAV latency-based and accuracy-based IIV, during the task displayed greater reliability across sessions compared to DOT. During the NAV task-engagement, the executive function, planning, and motor performance profiles exhibited moderate to good reliability (ICC = 0.6–0.8), while during DOT, executive function and spatial memory accuracy profiles exhibited fair to moderate reliability (ICC = 0.3–0.6). Additionally, reliability across tasks was more stable when three sessions were used in the ICC calculation relative to two sessions. Discussion: Our findings suggest that “motor signature” data during the NAV tasks were a more reliable marker for early diagnosis of aMCI than DOT. This result accentuates the importance of utilizing motor performance data as a metric for aMCI populations where memory decline is often the behavioral outcome of interest. In conclusion, custom SG with DTW performance data provide an ecological and reliable approach for cognitive assessment across multiple sessions and thus can be used as a useful tool for tracking longitudinal change in observational and interventional studies on aMCI. PMID:25954193

Focused attention in a simple dichotic listening task: an fMRI experiment.

PubMed

Jäncke, Lutz; Specht, Karsten; Shah, Joni Nadim; Hugdahl, Kenneth

2003-04-01

Whole-head functional magnetic resonance imaging (fMRI) was used in nine neurologically intact subjects to measure the hemodynamic responses in the context of dichotic listening (DL). In order to eliminate the influence of verbal information processing, tones of different frequencies were used as stimuli. Three different dichotic listening tasks were used: the subjects were instructed to either concentrate on the stimuli presented in both ears (DIV), or only in the left (FL) or right (FR) ear and to monitor the auditory input for a specific target tone. When the target tone was detected, the subjects were required to indicate this by pressing a response button. Compared to the resting state, all dichotic listening tasks evoked strong hemodynamic responses within a distributed network comprising of temporal, parietal, and frontal brain areas. Thus, it is clear that dichotic listening makes use of various cognitive functions located within the dorsal and ventral stream of auditory information processing (i.e., the 'what' and 'where' streams). Comparing the three different dichotic listening conditions with each other only revealed a significant difference in the pre-SMA and within the left planum temporale area. The pre-SMA was generally more strongly activated during the DIV condition than during the FR and FL conditions. Within the planum temporale, the strongest activation was found during the FR condition and the weakest during the DIV condition. These findings were taken as evidence that even a simple dichotic listening task such as the one used here, makes use of a distributed neural network comprising of the dorsal and ventral stream of auditory information processing. In addition, these results support the previously made assumption that planum temporale activation is modulated by attentional strategies. Finally, the present findings uncovered that the pre-SMA, which is mostly thought to be involved in higher-order motor control processes, is also involved in cognitive processes operative during dichotic listening.

Modeling shared resources with generalized synchronization within a Petri net bottom-up approach.

PubMed

Ferrarini, L; Trioni, M

1996-01-01

This paper proposes a simple and effective way to represent shared resources in manufacturing systems within a Petri net model previously developed. Such a model relies on the bottom-up and modular approach to synthesis and analysis. The designer may define elementary tasks and then connect them with one another with three kinds of connections: self-loops, inhibitor arcs and simple synchronizations. A theoretical framework has been established for the analysis of liveness and reversibility of such models. The generalized synchronization, here formalized, represents an extension of the simple synchronization, allowing the merging of suitable subnets among elementary tasks. It is proved that under suitable, but not restrictive, hypotheses the generalized synchronization may be substituted for a simple one, thus being compatible with all the developed theoretical body.

In-Situ Real-Time Focus Detection during Laser Processing Using Double-Hole Masks and Advanced Image Sensor Software

PubMed Central

Hoang, Phuong Le; Ahn, Sanghoon; Kim, Jeng-o; Kang, Heeshin; Noh, Jiwhan

2017-01-01

In modern high-intensity ultrafast laser processing, detecting the focal position of the working laser beam, at which the intensity is the highest and the beam diameter is the lowest, and immediately locating the target sample at that point are challenging tasks. A system that allows in-situ real-time focus determination and fabrication using a high-power laser has been in high demand among both engineers and scientists. Conventional techniques require the complicated mathematical theory of wave optics, employing interference as well as diffraction phenomena to detect the focal position; however, these methods are ineffective and expensive for industrial application. Moreover, these techniques could not perform detection and fabrication simultaneously. In this paper, we propose an optical design capable of detecting the focal point and fabricating complex patterns on a planar sample surface simultaneously. In-situ real-time focus detection is performed using a bandpass filter, which only allows for the detection of laser transmission. The technique enables rapid, non-destructive, and precise detection of the focal point. Furthermore, it is sufficiently simple for application in both science and industry for mass production, and it is expected to contribute to the next generation of laser equipment, which can be used to fabricate micro-patterns with high complexity. PMID:28671566

Is Rest Really Rest? Resting State Functional Connectivity during Rest and Motor Task Paradigms.

PubMed

Jurkiewicz, Michael T; Crawley, Adrian P; Mikulis, David J

2018-04-18

Numerous studies have identified the default mode network (DMN) within the brain of healthy individuals, which has been attributed to the ongoing mental activity of the brain during the wakeful resting-state. While engaged during specific resting-state fMRI paradigms, it remains unclear as to whether traditional block-design simple movement fMRI experiments significantly influence the default mode network or other areas. Using blood-oxygen level dependent (BOLD) fMRI we characterized the pattern of functional connectivity in healthy subjects during a resting-state paradigm and compared this to the same resting-state analysis performed on motor task data residual time courses after regressing out the task paradigm. Using seed-voxel analysis to define the DMN, the executive control network (ECN), and sensorimotor, auditory and visual networks, the resting-state analysis of the residual time courses demonstrated reduced functional connectivity in the motor network and reduced connectivity between the insula and the ECN compared to the standard resting-state datasets. Overall, performance of simple self-directed motor tasks does little to change the resting-state functional connectivity across the brain, especially in non-motor areas. This would suggest that previously acquired fMRI studies incorporating simple block-design motor tasks could be mined retrospectively for assessment of the resting-state connectivity.

Exploiting Acoustic and Syntactic Features for Automatic Prosody Labeling in a Maximum Entropy Framework

PubMed Central

Sridhar, Vivek Kumar Rangarajan; Bangalore, Srinivas; Narayanan, Shrikanth S.

2009-01-01

In this paper, we describe a maximum entropy-based automatic prosody labeling framework that exploits both language and speech information. We apply the proposed framework to both prominence and phrase structure detection within the Tones and Break Indices (ToBI) annotation scheme. Our framework utilizes novel syntactic features in the form of supertags and a quantized acoustic–prosodic feature representation that is similar to linear parameterizations of the prosodic contour. The proposed model is trained discriminatively and is robust in the selection of appropriate features for the task of prosody detection. The proposed maximum entropy acoustic–syntactic model achieves pitch accent and boundary tone detection accuracies of 86.0% and 93.1% on the Boston University Radio News corpus, and, 79.8% and 90.3% on the Boston Directions corpus. The phrase structure detection through prosodic break index labeling provides accuracies of 84% and 87% on the two corpora, respectively. The reported results are significantly better than previously reported results and demonstrate the strength of maximum entropy model in jointly modeling simple lexical, syntactic, and acoustic features for automatic prosody labeling. PMID:19603083

The Use of Digital Technology in Finding Multiple Paths to Solve and Extend an Equilateral Triangle Task

ERIC Educational Resources Information Center

Santos-Trigo, Manuel; Reyes-Rodriguez, Aaron

2016-01-01

Mathematical tasks are crucial elements for teachers to orient, foster and assess students' processes to comprehend and develop mathematical knowledge. During the process of working and solving a task, searching for or discussing multiple solution paths becomes a powerful strategy for students to engage in mathematical thinking. A simple task that…

Focused Attention Deficits in Patients with Alzheimer's Disease and Mild Cognitive Impairment

ERIC Educational Resources Information Center

Levinoff, E.J.; Saumier, D.; Chertkow, H.

2005-01-01

Reaction time (RT) tasks take various forms, and can assess psychomotor speed, (i.e., simple reaction time task), and focused attention (i.e., choice reaction time (CRT) task). If cues are provided before stimulus presentation (i.e., cued choice reaction time (CCRT) task), then a cueing effect can also be assessed. A limited number of studies have…

Influence of social presence on eye movements in visual search tasks.

PubMed

Liu, Na; Yu, Ruifeng

2017-12-01

This study employed an eye-tracking technique to investigate the influence of social presence on eye movements in visual search tasks. A total of 20 male subjects performed visual search tasks in a 2 (target presence: present vs. absent) × 2 (task complexity: complex vs. simple) × 2 (social presence: alone vs. a human audience) within-subject experiment. Results indicated that the presence of an audience could evoke a social facilitation effect on response time in visual search tasks. Compared with working alone, the participants made fewer and shorter fixations, larger saccades and shorter scan path in simple search tasks and more and longer fixations, smaller saccades and longer scan path in complex search tasks when working with an audience. The saccade velocity and pupil diameter in the audience-present condition were larger than those in the working-alone condition. No significant change in target fixation number was observed between two social presence conditions. Practitioner Summary: This study employed an eye-tracking technique to examine the influence of social presence on eye movements in visual search tasks. Results clarified the variation mechanism and characteristics of oculomotor scanning induced by social presence in visual search.

Sensorimotor Model of Obstacle Avoidance in Echolocating Bats

PubMed Central

Vanderelst, Dieter; Holderied, Marc W.; Peremans, Herbert

2015-01-01

Bat echolocation is an ability consisting of many subtasks such as navigation, prey detection and object recognition. Understanding the echolocation capabilities of bats comes down to isolating the minimal set of acoustic cues needed to complete each task. For some tasks, the minimal cues have already been identified. However, while a number of possible cues have been suggested, little is known about the minimal cues supporting obstacle avoidance in echolocating bats. In this paper, we propose that the Interaural Intensity Difference (IID) and travel time of the first millisecond of the echo train are sufficient cues for obstacle avoidance. We describe a simple control algorithm based on the use of these cues in combination with alternating ear positions modeled after the constant frequency bat Rhinolophus rouxii. Using spatial simulations (2D and 3D), we show that simple phonotaxis can steer a bat clear from obstacles without performing a reconstruction of the 3D layout of the scene. As such, this paper presents the first computationally explicit explanation for obstacle avoidance validated in complex simulated environments. Based on additional simulations modelling the FM bat Phyllostomus discolor, we conjecture that the proposed cues can be exploited by constant frequency (CF) bats and frequency modulated (FM) bats alike. We hypothesize that using a low level yet robust cue for obstacle avoidance allows bats to comply with the hard real-time constraints of this basic behaviour. PMID:26502063

Gait-Related Brain Activity in People with Parkinson Disease with Freezing of Gait

PubMed Central

Peterson, Daniel S.; Pickett, Kristen A.; Duncan, Ryan; Perlmutter, Joel; Earhart, Gammon M.

2014-01-01

Approximately 50% of people with Parkinson disease experience freezing of gait, described as a transient inability to produce effective stepping. Complex gait tasks such as turning typically elicit freezing more commonly than simple gait tasks, such as forward walking. Despite the frequency of this debilitating and dangerous symptom, the brain mechanisms underlying freezing remain unclear. Gait imagery during functional magnetic resonance imaging permits investigation of brain activity associated with locomotion. We used this approach to better understand neural function during gait-like tasks in people with Parkinson disease who experience freezing- “FoG+” and people who do not experience freezing- ”FoG−“. Nine FoG+ and nine FoG− imagined complex gait tasks (turning, backward walking), simple gait tasks (forward walking), and quiet standing during measurements of blood oxygen level dependent (BOLD) signal. Changes in BOLD signal (i.e. beta weights) during imagined walking and imagined standing were analyzed across FoG+ and FoG− groups in locomotor brain regions including supplementary motor area, globus pallidus, putamen, mesencephalic locomotor region, and cerebellar locomotor region. Beta weights in locomotor regions did not differ for complex tasks compared to simple tasks in either group. Across imagined gait tasks, FoG+ demonstrated significantly lower beta weights in the right globus pallidus with respect to FoG−. FoG+ also showed trends toward lower beta weights in other right-hemisphere locomotor regions (supplementary motor area, mesencephalic locomotor region). Finally, during imagined stand, FoG+ exhibited lower beta weights in the cerebellar locomotor region with respect to FoG−. These data support previous results suggesting FoG+ exhibit dysfunction in a number of cortical and subcortical regions, possibly with asymmetric dysfunction towards the right hemisphere. PMID:24595265

Extracting Drug-Drug Interactions with Word and Character-Level Recurrent Neural Networks

PubMed Central

Kavuluru, Ramakanth; Rios, Anthony; Tran, Tung

2017-01-01

Drug-drug interactions (DDIs) are known to be responsible for nearly a third of all adverse drug reactions. Hence several current efforts focus on extracting signal from EMRs to prioritize DDIs that need further exploration. To this end, being able to extract explicit mentions of DDIs in free text narratives is an important task. In this paper, we explore recurrent neural network (RNN) architectures to detect and classify DDIs from unstructured text using the DDIExtraction dataset from the SemEval 2013 (task 9) shared task. Our methods are in line with those used in other recent deep learning efforts for relation extraction including DDI extraction. However, to our knowledge, we are the first to investigate the potential of character-level RNNs (Char-RNNs) for DDI extraction (and relation extraction in general). Furthermore, we explore a simple but effective model bootstrapping method to (a). build model averaging ensembles, (b). derive confidence intervals around mean micro-F scores (MMF), and (c). assess the average behavior of our methods. Without any rule based filtering of negative examples, a popular heuristic used by most earlier efforts, we achieve an MMF of 69.13. By adding simple replicable heuristics to filter negative instances we are able to achieve an MMF of 70.38. Furthermore, our best ensembles produce micro F-scores of 70.81 (without filtering) and 72.13 (with filtering), which are superior to metrics reported in published results. Although Char-RNNs turnout to be inferior to regular word based RNN models in overall comparisons, we find that ensembling models from both architectures results in nontrivial gains over simply using either alone, indicating that they complement each other. PMID:29034375

Investigating the visual span in comparative search: the effects of task difficulty and divided attention.

PubMed

Pomplun, M; Reingold, E M; Shen, J

2001-09-01

In three experiments, participants' visual span was measured in a comparative visual search task in which they had to detect a local match or mismatch between two displays presented side by side. Experiment 1 manipulated the difficulty of the comparative visual search task by contrasting a mismatch detection task with a substantially more difficult match detection task. In Experiment 2, participants were tested in a single-task condition involving only the visual task and a dual-task condition in which they concurrently performed an auditory task. Finally, in Experiment 3, participants performed two dual-task conditions, which differed in the difficulty of the concurrent auditory task. Both the comparative search task difficulty (Experiment 1) and the divided attention manipulation (Experiments 2 and 3) produced strong effects on visual span size.

Syntactic processing as a marker for cognitive impairment in amyotrophic lateral sclerosis

PubMed Central

Tsermentseli, Stella; Leigh, P. Nigel; Taylor, Lorna J.; Radunovic, Aleksandar; Catani, Marco; Goldstein, Laura H.

2016-01-01

Despite recent interest in cognitive changes in patients with amyotrophic lateral sclerosis (ALS), investigations of language function looking at the level of word, sentence and discourse processing are relatively scarce. Data were obtained from 26 patients with sporadic ALS and 26 healthy controls matched for age, education, gender, anxiety, depression and executive function performance. Standardized language tasks included confrontation naming, semantic access, and syntactic comprehension. Quantitative production analysis (QPA) was used to analyse connected speech samples of the Cookie Theft picture description task. Results showed that the ALS patients were impaired on standardized measures of grammatical comprehension and action/verb semantics. At the level of discourse, ALS patients were impaired on measures of syntactic complexity and fluency; however, the latter could be better explained by disease related factors. Discriminant analysis revealed that syntactic measures differentiated ALS patients from controls. In conclusion, patients with ALS exhibit deficits in receptive and expressive language on tasks of comprehension and connected speech production, respectively. Our findings suggest that syntactic processing deficits seem to be the predominant feature of language impairment in ALS and that these deficits can be detected by relatively simple language tests. PMID:26312952

Syntactic processing as a marker for cognitive impairment in amyotrophic lateral sclerosis.

PubMed

Tsermentseli, Stella; Leigh, P Nigel; Taylor, Lorna J; Radunovic, Aleksandar; Catani, Marco; Goldstein, Laura H

2015-01-01

Despite recent interest in cognitive changes in patients with amyotrophic lateral sclerosis (ALS), investigations of language function looking at the level of word, sentence and discourse processing are relatively scarce. Data were obtained from 26 patients with sporadic ALS and 26 healthy controls matched for age, education, gender, anxiety, depression and executive function performance. Standardized language tasks included confrontation naming, semantic access, and syntactic comprehension. Quantitative production analysis (QPA) was used to analyse connected speech samples of the Cookie Theft picture description task. Results showed that the ALS patients were impaired on standardized measures of grammatical comprehension and action/verb semantics. At the level of discourse, ALS patients were impaired on measures of syntactic complexity and fluency; however, the latter could be better explained by disease related factors. Discriminant analysis revealed that syntactic measures differentiated ALS patients from controls. In conclusion, patients with ALS exhibit deficits in receptive and expressive language on tasks of comprehension and connected speech production, respectively. Our findings suggest that syntactic processing deficits seem to be the predominant feature of language impairment in ALS and that these deficits can be detected by relatively simple language tests.

A portable, multi-channel fNIRS system for prefrontal cortex: Preliminary study on neurofeedback and imagery tasks (Conference Presentation)

NASA Astrophysics Data System (ADS)

Paik, Seung-ho; Kim, Beop-Min

2016-03-01

fNIRS is a neuroimaging technique which uses near-infrared light source in the 700-1000 nm range and enables to detect hemodynamic changes (i.e., oxygenated hemoglobin, deoxygenated hemoglobin, blood volume) as a response to various brain processes. In this study, we developed a new, portable, prefrontal fNIRS system which has 12 light sources, 15 detectors and 108 channels with a sampling rate of 2 Hz. The wavelengths of light source are 780nm and 850nm. ATxmega128A1, 8bit of Micro controller unit (MCU) with 200~4095 resolution along with MatLab data acquisition algorithm was utilized. We performed a simple left and right finger movement imagery tasks which produced statistically significant changes of oxyhemoglobin concentrations in the dorsolateral prefrontal cortex (dlPFC) areas. We observed that the accuracy of the imagery tasks can be improved by carrying out neurofeedback training, during which a real-time feedback signal is provided to a participating subject. The effects of the neurofeedback training was later visually verified using the 3D NIRfast imaging. Our portable fNIRS system may be useful in non-constraint environment for various clinical diagnoses.

Is Neural Activity Detected by ERP-Based Brain-Computer Interfaces Task Specific?

PubMed

Wenzel, Markus A; Almeida, Inês; Blankertz, Benjamin

2016-01-01

Brain-computer interfaces (BCIs) that are based on event-related potentials (ERPs) can estimate to which stimulus a user pays particular attention. In typical BCIs, the user silently counts the selected stimulus (which is repeatedly presented among other stimuli) in order to focus the attention. The stimulus of interest is then inferred from the electroencephalogram (EEG). Detecting attention allocation implicitly could be also beneficial for human-computer interaction (HCI), because it would allow software to adapt to the user's interest. However, a counting task would be inappropriate for the envisaged implicit application in HCI. Therefore, the question was addressed if the detectable neural activity is specific for silent counting, or if it can be evoked also by other tasks that direct the attention to certain stimuli. Thirteen people performed a silent counting, an arithmetic and a memory task. The tasks required the subjects to pay particular attention to target stimuli of a random color. The stimulus presentation was the same in all three tasks, which allowed a direct comparison of the experimental conditions. Classifiers that were trained to detect the targets in one task, according to patterns present in the EEG signal, could detect targets in all other tasks (irrespective of some task-related differences in the EEG). The neural activity detected by the classifiers is not strictly task specific but can be generalized over tasks and is presumably a result of the attention allocation or of the augmented workload. The results may hold promise for the transfer of classification algorithms from BCI research to implicit relevance detection in HCI.

Modeling Age-Related Differences in Immediate Memory Using SIMPLE

ERIC Educational Resources Information Center

Surprenant, Aimee M.; Neath, Ian; Brown, Gordon D. A.

2006-01-01

In the SIMPLE model (Scale Invariant Memory and Perceptual Learning), performance on memory tasks is determined by the locations of items in multidimensional space, and better performance is associated with having fewer close neighbors. Unlike most previous simulations with SIMPLE, the ones reported here used measured, rather than assumed,…

The ability of people with Parkinson's disease to modify dual-task performance in response to instructions during simple and complex walking tasks.

PubMed

Kelly, Valerie E; Shumway-Cook, Anne

2014-01-01

Gait impairments are a common and consequential motor symptom in Parkinson's disease (PD). A cognitive strategy that incorporates instructions to concentrate on specific parameters of walking is an effective approach to gait rehabilitation for persons with PD during single-task and simple dual-task walking conditions. This study examined the ability to modify dual-task walking in response to instructions during a complex walking task in people with PD compared to healthy older adults (HOA). Eleven people with PD and twelve HOA performed a cognitive task while walking with either a usual base or a narrow base of support. Dual-task walking and cognitive task performance were characterized under two conditions-when participants were instructed focus on walking and when they were instructed to focus on the cognitive task. During both usual base and narrow base walking, instructions affected cognitive task response latency, with slower performance when instructed to focus on walking compared to the cognitive task. Regardless of task or instructions, cognitive task performance was slower in participants with PD compared to HOA. During usual base walking, instructions influenced gait speed for both people with PD and HOA, with faster gait speed when instructed to focus on walking compared to the cognitive task. In contrast, during the narrow base walking, instructions affected gait speed only for HOA, but not for people with PD. This suggests that among people with PD the ability to modify walking in response to instructions depends on the complexity of the walking task.

Efficient probabilistic inference in generic neural networks trained with non-probabilistic feedback.

PubMed

Orhan, A Emin; Ma, Wei Ji

2017-07-26

Animals perform near-optimal probabilistic inference in a wide range of psychophysical tasks. Probabilistic inference requires trial-to-trial representation of the uncertainties associated with task variables and subsequent use of this representation. Previous work has implemented such computations using neural networks with hand-crafted and task-dependent operations. We show that generic neural networks trained with a simple error-based learning rule perform near-optimal probabilistic inference in nine common psychophysical tasks. In a probabilistic categorization task, error-based learning in a generic network simultaneously explains a monkey's learning curve and the evolution of qualitative aspects of its choice behavior. In all tasks, the number of neurons required for a given level of performance grows sublinearly with the input population size, a substantial improvement on previous implementations of probabilistic inference. The trained networks develop a novel sparsity-based probabilistic population code. Our results suggest that probabilistic inference emerges naturally in generic neural networks trained with error-based learning rules.Behavioural tasks often require probability distributions to be inferred about task specific variables. Here, the authors demonstrate that generic neural networks can be trained using a simple error-based learning rule to perform such probabilistic computations efficiently without any need for task specific operations.

fMRI activation patterns in an analytic reasoning task: consistency with EEG source localization

NASA Astrophysics Data System (ADS)

Li, Bian; Vasanta, Kalyana C.; O'Boyle, Michael; Baker, Mary C.; Nutter, Brian; Mitra, Sunanda

2010-03-01

Functional magnetic resonance imaging (fMRI) is used to model brain activation patterns associated with various perceptual and cognitive processes as reflected by the hemodynamic (BOLD) response. While many sensory and motor tasks are associated with relatively simple activation patterns in localized regions, higher-order cognitive tasks may produce activity in many different brain areas involving complex neural circuitry. We applied a recently proposed probabilistic independent component analysis technique (PICA) to determine the true dimensionality of the fMRI data and used EEG localization to identify the common activated patterns (mapped as Brodmann areas) associated with a complex cognitive task like analytic reasoning. Our preliminary study suggests that a hybrid GLM/PICA analysis may reveal additional regions of activation (beyond simple GLM) that are consistent with electroencephalography (EEG) source localization patterns.

From network heterogeneities to familiarity detection and hippocampal memory management

PubMed Central

Wang, Jane X.; Poe, Gina; Zochowski, Michal

2009-01-01

Hippocampal-neocortical interactions are key to the rapid formation of novel associative memories in the hippocampus and consolidation to long term storage sites in the neocortex. We investigated the role of network correlates during information processing in hippocampal-cortical networks. We found that changes in the intrinsic network dynamics due to the formation of structural network heterogeneities alone act as a dynamical and regulatory mechanism for stimulus novelty and familiarity detection, thereby controlling memory management in the context of memory consolidation. This network dynamic, coupled with an anatomically established feedback between the hippocampus and the neocortex, recovered heretofore unexplained properties of neural activity patterns during memory management tasks which we observed during sleep in multiunit recordings from behaving animals. Our simple dynamical mechanism shows an experimentally matched progressive shift of memory activation from the hippocampus to the neocortex and thus provides the means to achieve an autonomous off-line progression of memory consolidation. PMID:18999453

Testing the tests--an empirical evaluation of screening tests for the detection of cognitive impairment in aviators.

PubMed

Stokes, A F; Banich, M T; Elledge, V C

1991-08-01

The FAA has expressed concern that flight safety could be compromised by undetected cognitive impairment in pilots due to conditions such as substance abuse, mental illness, and neuropsychological problems. Interest has been shown in the possibility of adding a brief "mini-mental exam," or a simple automated test-battery to the standard flight medical to screen for such conditions. The research reported here involved the empirical evaluation of two "mini-mental exams," two paper-and-pencil test batteries, and a prototype version of an automated screening battery. Sensitivity, specificity, and positive predictive value were calculated for each sub-task in a discriminant study of 54 pilots and 62 individuals from a heterogeneous clinical population. Results suggest that the "mini-mental exams" are poor candidates for a screening test. The automated battery showed the best discrimination performance, in part because of the incorporation of dual-task tests of divided attention performance. These tests appear to be particularly sensitive to otherwise difficult-to-detect cognitive impairments of a mild or subtle nature. The use of an automated battery of tests as a screening instrument does appear to be feasible in principle, but the practical success of a screening program is heavily dependent upon the actual prevalence of cognitive impairment in the medical applicant population.

Covert effects of "one drink" of alcohol on brain processes related to car driving: an event-related potential study.

PubMed

Ebe, Kazutoshi; Itoh, Kosuke; Kwee, Ingrid L; Nakada, Tsutomu

2015-04-23

The effects of a low dose of alcohol on car driving remain controversial. To address this issue, event-related potentials were recorded while subjects performed a simple car-following task in a driving simulator before and after consuming either "one drink" of beer (representing one standard alcoholic beverage containing 14 g of alcohol) or mineral water (control condition). Subjects who had consumed the determined amount of alcohol demonstrated no detectable outward behavioral signs of intoxication while performing the driving task, an observation in agreement with previous findings. However, the parietal P3 elicited by the brake lights of the preceding car was significantly reduced in amplitude, approximately 50% that observed under the control condition, likely indicating alteration of the neural processing of visual information critical for safe driving. The finding suggests that alcohol begins to affect neural processes for driving even at quantities too low to modify behavior. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Goal-directed or aimless? EEG differences during the preparation of a reach-and-touch task.

PubMed

Pereira, Joana; Ofner, Patrick; Muller-Putz, Gernot R

2015-08-01

The natural control of neuroprostheses is currently a challenge in both rehabilitation engineering and brain-computer interfaces (BCIs) research. One of the recurrent problems is to know exactly when to activate such devices. For the execution of the most common activities of daily living, these devices only need to be active when in the presence of a goal. Therefore, we believe that the distinction between the planning of goal-directed and aimless movements, using non-invasive recordings, can be useful for the implementation of a simple and effective activation method for these devices. We investigated whether those differences are detectable during a reach-and-touch task, using electroencephalography (EEG). Event-related potentials and oscillatory activity changes were studied. Our results show that there are statistically significant differences between both types of movement. Combining this information with movement decoding would allow a natural control strategy for BCIs, exclusively relying on the cognitive processes behind movement preparation and execution.

Testing sensory evidence against mnemonic templates

PubMed Central

Myers, Nicholas E; Rohenkohl, Gustavo; Wyart, Valentin; Woolrich, Mark W; Nobre, Anna C; Stokes, Mark G

2015-01-01

Most perceptual decisions require comparisons between current input and an internal template. Classic studies propose that templates are encoded in sustained activity of sensory neurons. However, stimulus encoding is itself dynamic, tracing a complex trajectory through activity space. Which part of this trajectory is pre-activated to reflect the template? Here we recorded magneto- and electroencephalography during a visual target-detection task, and used pattern analyses to decode template, stimulus, and decision-variable representation. Our findings ran counter to the dominant model of sustained pre-activation. Instead, template information emerged transiently around stimulus onset and quickly subsided. Cross-generalization between stimulus and template coding, indicating a shared neural representation, occurred only briefly. Our results are compatible with the proposal that template representation relies on a matched filter, transforming input into task-appropriate output. This proposal was consistent with a signed difference response at the perceptual decision stage, which can be explained by a simple neural model. DOI: http://dx.doi.org/10.7554/eLife.09000.001 PMID:26653854

The Influence of Complexity in Monologic versus Dialogic Tasks in Dutch L2

ERIC Educational Resources Information Center

Michel, Marije C.; Kuiken, Folkert; Vedder, Ineke

2007-01-01

This study puts the Cognition Hypothesis (Robinson 2005) to the test with respect to its predictions of the effects of changes in task complexity ([plus or minus] few elements) and task condition ([plus or minus] monologic) on L2 performance. 44 learners of Dutch performed both a simple and a complex oral task in either a monologic or a dialogic…

Evaluation of Ground Vibrations Induced by Military Noise Sources

DTIC Science & Technology

2006-08-01

1 Task 2—Determine the acoustic -to-seismic coupling coefficients C1 and C2 ...................... 1 Task 3—Computational modeling ...Determine the acoustic -to-seismic coupling coefficients C1 and C2 ....................45 Task 3—Computational modeling of acoustically induced ground...ground conditions. Task 3—Computational modeling of acoustically induced ground motion The simple model of blast sound interaction with the

Processing of unattended, simple negative pictures resists perceptual load.

PubMed

Sand, Anders; Wiens, Stefan

2011-05-11

As researchers debate whether emotional pictures can be processed irrespective of spatial attention and perceptual load, negative and neutral pictures of simple figure-ground composition were shown at fixation and were surrounded by one, two, or three letters. When participants performed a picture discrimination task, there was evidence for motivated attention; that is, an early posterior negativity (EPN) and late positive potential (LPP) to negative versus neutral pictures. When participants performed a letter discrimination task, the EPN was unaffected whereas the LPP was reduced. Although performance decreased substantially with the number of letters (one to three), the LPP did not decrease further. Therefore, attention to simple, negative pictures at fixation seems to resist manipulations of perceptual load.

Self-Reported Versus Performance-Based Assessments of a Simple Mobility Task Among Older Adults in the Emergency Department.

PubMed

Roedersheimer, Kyle M; Pereira, Greg F; Jones, Christopher W; Braz, Valerie A; Mangipudi, Sowmya A; Platts-Mills, Timothy F

2016-02-01

Accurate information about the mobility of independently living older adults is essential in determining whether they may be safely discharged home from the emergency department (ED). We assess the accuracy of self-reported ability to complete a simple mobility task among older ED patients. This was a cross-sectional study of cognitively intact patients aged 65 years and older who were neither nursing home residents nor critically ill, conducted in 2 academic EDs. Consenting participants were asked whether they could get out of bed, walk 10 feet, turn around, and get back in bed without assistance, and if not, whether they could perform this task with a cane, walker, or assistance. Each participant was then asked to perform the task and was provided with a mobility device or assistance as needed. Of 272 patients who met eligibility criteria and answered the physical task question, 161 (59%) said they could do the task unassisted, 45 (17%) said they could do it with a cane or walker, 21 (8%) said they could do it with assistance, and 45 (17%) said they would be unable to do it even with assistance. Among those who said they could do the task either with or without assistance and who were subsequently willing to attempt the task (N=172), discrepancies between self-reported ability and actual performance were common. Of those who said they could perform the task without assistance, 12% required some assistance or were unable to complete the task. Of those who said they could perform the task with a cane or walker, 48% required either assistance or were unable to perform the task. Of those who said they could perform the task with assistance, 24% were unable to perform the task even with assistance. In this sample of older adults receiving care in the ED, the accuracy of their self-reported ability to perform a simple mobility task was poor, particularly for those who reported some need for assistance. For older adults being considered for discharge who report a need for assistance with mobility, direct observation of the patient's mobility by a member of the emergency care team should be considered. Copyright © 2015 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

The P/N (Positive-to-Negative Links) Ratio in Complex Networks-A Promising In Silico Biomarker for Detecting Changes Occurring in the Human Microbiome.

PubMed

Ma, Zhanshan Sam

2018-05-01

Relatively little progress in the methodology for differentiating between the healthy and diseased microbiomes, beyond comparing microbial community diversities with traditional species richness or Shannon index, has been made. Network analysis has increasingly been called for the task, but most currently available microbiome datasets only allows for the construction of simple species correlation networks (SCNs). The main results from SCN analysis are a series of network properties such as network degree and modularity, but the metrics for these network properties often produce inconsistent evidence. We propose a simple new network property, the P/N ratio, defined as the ratio of positive links to the number of negative links in the microbial SCN. We postulate that the P/N ratio should reflect the balance between facilitative and inhibitive interactions among microbial species, possibly one of the most important changes occurring in diseased microbiome. We tested our hypothesis with five datasets representing five major human microbiome sites and discovered that the P/N ratio exhibits contrasting differences between healthy and diseased microbiomes and may be harnessed as an in silico biomarker for detecting disease-associated changes in the human microbiome, and may play an important role in personalized diagnosis of the human microbiome-associated diseases.

Direct Identification of On-Bead Peptides Using Surface-Enhanced Raman Spectroscopic Barcoding System for High-Throughput Bioanalysis

PubMed Central

Kang, Homan; Jeong, Sinyoung; Koh, Yul; Geun Cha, Myeong; Yang, Jin-Kyoung; Kyeong, San; Kim, Jaehi; Kwak, Seon-Yeong; Chang, Hye-Jin; Lee, Hyunmi; Jeong, Cheolhwan; Kim, Jong-Ho; Jun, Bong-Hyun; Kim, Yong-Kweon; Hong Jeong, Dae; Lee, Yoon-Sik

2015-01-01

Recently, preparation and screening of compound libraries remain one of the most challenging tasks in drug discovery, biomarker detection, and biomolecular profiling processes. So far, several distinct encoding/decoding methods such as chemical encoding, graphical encoding, and optical encoding have been reported to identify those libraries. In this paper, a simple and efficient surface-enhanced Raman spectroscopic (SERS) barcoding method using highly sensitive SERS nanoparticles (SERS ID) is presented. The 44 kinds of SERS IDs were able to generate simple codes and could possibly generate more than one million kinds of codes by incorporating combinations of different SERS IDs. The barcoding method exhibited high stability and reliability under bioassay conditions. The SERS ID encoding based screening platform can identify the peptide ligand on the bead and also quantify its binding affinity for specific protein. We believe that our SERS barcoding technology is a promising method in the screening of one-bead-one-compound (OBOC) libraries for drug discovery. PMID:26017924

Direct identification of on-bead peptides using surface-enhanced Raman spectroscopic barcoding system for high-throughput bioanalysis.

PubMed

Kang, Homan; Jeong, Sinyoung; Koh, Yul; Geun Cha, Myeong; Yang, Jin-Kyoung; Kyeong, San; Kim, Jaehi; Kwak, Seon-Yeong; Chang, Hye-Jin; Lee, Hyunmi; Jeong, Cheolhwan; Kim, Jong-Ho; Jun, Bong-Hyun; Kim, Yong-Kweon; Hong Jeong, Dae; Lee, Yoon-Sik

2015-05-28

Recently, preparation and screening of compound libraries remain one of the most challenging tasks in drug discovery, biomarker detection, and biomolecular profiling processes. So far, several distinct encoding/decoding methods such as chemical encoding, graphical encoding, and optical encoding have been reported to identify those libraries. In this paper, a simple and efficient surface-enhanced Raman spectroscopic (SERS) barcoding method using highly sensitive SERS nanoparticles (SERS ID) is presented. The 44 kinds of SERS IDs were able to generate simple codes and could possibly generate more than one million kinds of codes by incorporating combinations of different SERS IDs. The barcoding method exhibited high stability and reliability under bioassay conditions. The SERS ID encoding based screening platform can identify the peptide ligand on the bead and also quantify its binding affinity for specific protein. We believe that our SERS barcoding technology is a promising method in the screening of one-bead-one-compound (OBOC) libraries for drug discovery.

Reaction time, impulsivity, and attention in hyperactive children and controls: a video game technique.

PubMed

Mitchell, W G; Chavez, J M; Baker, S A; Guzman, B L; Azen, S P

1990-07-01

Maturation of sustained attention was studied in a group of 52 hyperactive elementary school children and 152 controls using a microcomputer-based test formatted to resemble a video game. In nonhyperactive children, both simple and complex reaction time decreased with age, as did variability of response time. Omission errors were extremely infrequent on simple reaction time and decreased with age on the more complex tasks. Commission errors had an inconsistent relationship with age. Hyperactive children were slower, more variable, and made more errors on all segments of the game than did controls. Both motor speed and calculated mental speed were slower in hyperactive children, with greater discrepancy for responses directed to the nondominant hand, suggesting that a selective right hemisphere deficit may be present in hyperactives. A summary score (number of individual game scores above the 95th percentile) of 4 or more detected 60% of hyperactive subjects with a false positive rate of 5%. Agreement with the Matching Familiar Figures Test was 75% in the hyperactive group.

Visual task performance in the blind with the BrainPort V100 Vision Aid.

PubMed

Stronks, H Christiaan; Mitchell, Ellen B; Nau, Amy C; Barnes, Nick

2016-10-01

The BrainPort® V100 Vision Aid is a non-invasive assistive device for the blind based on sensory substitution. The device translates camera images into electrotactile stimuli delivered to the tongue. The BrainPort has recently received the CE mark and FDA approval and it is currently marketed to augment, rather than replace, the traditional assistive technologies such as the white cane or guide dog. Areas covered: In this work, we will review the functional studies performed to date with the BrainPort and we will highlight the critical factors that determine device performance, including the technology behind the BrainPort, the impediments to assessing device performance, and the impact of device training and rehabilitation. Expert commentary: The BrainPort enables blind people to perceive light, identify simple objects, recognize short words, localize simple objects, and detect motion and orientation of objects. To achieve this, proper rehabilitation and training regimes are crucial.

Can Spectro-Temporal Complexity Explain the Autistic Pattern of Performance on Auditory Tasks?

ERIC Educational Resources Information Center

Samson, Fabienne; Mottron, Laurent; Jemel, Boutheina; Belin, Pascal; Ciocca, Valter

2006-01-01

To test the hypothesis that level of neural complexity explain the relative level of performance and brain activity in autistic individuals, available behavioural, ERP and imaging findings related to the perception of increasingly complex auditory material under various processing tasks in autism were reviewed. Tasks involving simple material…

The Effects of Mode and Task Complexity on Second Language Production

ERIC Educational Resources Information Center

Vasylets, Olena; Gilabert, Roger; Manchón, Rosa M.

2017-01-01

Taking a psycholinguistic orientation within task-based language teaching scholarship, this study investigated the effects of mode (oral vs. written) and task complexity on second language (L2) performance. The participants were 78 Catalan/Spanish learners of English as a foreign language. Half of the participants performed the simple and complex…

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.…

Intra-individual reaction time variability and all-cause mortality over 17 years: a community-based cohort study.

PubMed

Batterham, Philip J; Bunce, David; Mackinnon, Andrew J; Christensen, Helen

2014-01-01

very few studies have examined the association between intra-individual reaction time variability and subsequent mortality. Furthermore, the ability of simple measures of variability to predict mortality has not been compared with more complex measures. a prospective cohort study of 896 community-based Australian adults aged 70+ were interviewed up to four times from 1990 to 2002, with vital status assessed until June 2007. From this cohort, 770-790 participants were included in Cox proportional hazards regression models of survival. Vital status and time in study were used to conduct survival analyses. The mean reaction time and three measures of intra-individual reaction time variability were calculated separately across 20 trials of simple and choice reaction time tasks. Models were adjusted for a range of demographic, physical health and mental health measures. greater intra-individual simple reaction time variability, as assessed by the raw standard deviation (raw SD), coefficient of variation (CV) or the intra-individual standard deviation (ISD), was strongly associated with an increased hazard of all-cause mortality in adjusted Cox regression models. The mean reaction time had no significant association with mortality. intra-individual variability in simple reaction time appears to have a robust association with mortality over 17 years. Health professionals such as neuropsychologists may benefit in their detection of neuropathology by supplementing neuropsychiatric testing with the straightforward process of testing simple reaction time and calculating raw SD or CV.

Robot-assisted surgery: an emerging platform for human neuroscience research

PubMed Central

Jarc, Anthony M.; Nisky, Ilana

2015-01-01

Classic studies in human sensorimotor control use simplified tasks to uncover fundamental control strategies employed by the nervous system. Such simple tasks are critical for isolating specific features of motor, sensory, or cognitive processes, and for inferring causality between these features and observed behavioral changes. However, it remains unclear how these theories translate to complex sensorimotor tasks or to natural behaviors. Part of the difficulty in performing such experiments has been the lack of appropriate tools for measuring complex motor skills in real-world contexts. Robot-assisted surgery (RAS) provides an opportunity to overcome these challenges by enabling unobtrusive measurements of user behavior. In addition, a continuum of tasks with varying complexity—from simple tasks such as those in classic studies to highly complex tasks such as a surgical procedure—can be studied using RAS platforms. Finally, RAS includes a diverse participant population of inexperienced users all the way to expert surgeons. In this perspective, we illustrate how the characteristics of RAS systems make them compelling platforms to extend many theories in human neuroscience, as well as, to develop new theories altogether. PMID:26089785

Transcranial direct current stimulation (tDCS) to the supplementary motor area (SMA) influences performance on motor tasks.

PubMed

Hupfeld, K E; Ketcham, C J; Schneider, H D

2017-03-01

The supplementary motor area (SMA) is believed to be highly involved in the planning and execution of both simple and complex motor tasks. This study aimed to examine the role of the SMA in planning the movements required to complete reaction time, balance, and pegboard tasks using anodal transcranial direct current stimulation (tDCS), which passes a weak electrical current between two electrodes, in order to modulate neuronal activity. Twenty healthy adults were counterbalanced to receive either tDCS (experimental condition) or no tDCS (control condition) for 3 days. During administration of tDCS, participants performed a balance task significantly faster than controls. After tDCS, subjects significantly improved their simple and choice reaction time. These results demonstrate that the SMA is highly involved in planning and executing fine and gross motor skill tasks and that tDCS is an effective modality for increasing SMA-related performance on these tasks. The findings may be generalizable and therefore indicate implications for future interventions using tDCS as a therapeutic tool.

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

Cell-assembly coding in several memory processes.

PubMed

Sakurai, Y

1998-01-01

The present paper discusses why the cell assembly, i.e., an ensemble population of neurons with flexible functional connections, is a tenable view of the basic code for information processes in the brain. The main properties indicating the reality of cell-assembly coding are neurons overlaps among different assemblies and connection dynamics within and among the assemblies. The former can be detected as multiple functions of individual neurons in processing different kinds of information. Individual neurons appear to be involved in multiple information processes. The latter can be detected as changes of functional synaptic connections in processing different kinds of information. Correlations of activity among some of the recorded neurons appear to change in multiple information processes. Recent experiments have compared several different memory processes (tasks) and detected these two main properties, indicating cell-assembly coding of memory in the working brain. The first experiment compared different types of processing of identical stimuli, i.e., working memory and reference memory of auditory stimuli. The second experiment compared identical processes of different types of stimuli, i.e., discriminations of simple auditory, simple visual, and configural auditory-visual stimuli. The third experiment compared identical processes of different types of stimuli with or without temporal processing of stimuli, i.e., discriminations of elemental auditory, configural auditory-visual, and sequential auditory-visual stimuli. Some possible features of the cell-assembly coding, especially "dual coding" by individual neurons and cell assemblies, are discussed for future experimental approaches. Copyright 1998 Academic Press.

Exploring the Cosmic Frontier, Task A - Direct Detection of Dark Matter, Task B - Experimental Particle Astrophysics

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

Matthews, John A.J.; Gold, Michael S.

This report summarizes the work of Task A and B for the period 2013-2016. For Task A the work is for direct detection of dark matter with the single-phase liquid argon experiment Mini-CLEAN. For Task B the work is for the search for new physics in the analysis of fluorescence events with the Auger experiment and for the search for the indirect detection of dark matter with the HAWC experiment.

The Attentional Boost Effect: Transient increases in attention to one task enhance performance in a second task.

PubMed

Swallow, Khena M; Jiang, Yuhong V

2010-04-01

Recent work on event perception suggests that perceptual processing increases when events change. An important question is how such changes influence the way other information is processed, particularly during dual-task performance. In this study, participants monitored a long series of distractor items for an occasional target as they simultaneously encoded unrelated background scenes. The appearance of an occasional target could have two opposite effects on the secondary task: It could draw attention away from the second task, or, as a change in the ongoing event, it could improve secondary task performance. Results were consistent with the second possibility. Memory for scenes presented simultaneously with the targets was better than memory for scenes that preceded or followed the targets. This effect was observed when the primary detection task involved visual feature oddball detection, auditory oddball detection, and visual color-shape conjunction detection. It was eliminated when the detection task was omitted, and when it required an arbitrary response mapping. The appearance of occasional, task-relevant events appears to trigger a temporal orienting response that facilitates processing of concurrently attended information (Attentional Boost Effect). Copyright 2009 Elsevier B.V. All rights reserved.

The Attentional Boost Effect: Transient Increases in Attention to One Task Enhance Performance in a Second Task

PubMed Central

Swallow, Khena M.; Jiang, Yuhong V.

2009-01-01

Recent work on event perception suggests that perceptual processing increases when events change. An important question is how such changes influence the way other information is processed, particularly during dual-task performance. In this study, participants monitored a long series of distractor items for an occasional target as they simultaneously encoded unrelated background scenes. The appearance of an occasional target could have two opposite effects on the secondary task: It could draw attention away from the second task, or, as a change in the ongoing event, it could improve secondary task performance. Results were consistent with the second possibility. Memory for scenes presented simultaneously with the targets was better than memory for scenes that preceded or followed the targets. This effect was observed when the primary detection task involved visual feature oddball detection, auditory oddball detection, and visual color-shape conjunction detection. It was eliminated when the detection task was omitted, and when it required an arbitrary response mapping. The appearance of occasional, task-relevant events appears to trigger a temporal orienting response that facilitates processing of concurrently attended information (Attentional Boost Effect). PMID:20080232

Development of motor speed and associated movements from 5 to 18 years.

PubMed

Gasser, Theo; Rousson, Valentin; Caflisch, Jon; Jenni, Oskar G

2010-03-01

To study the development of motor speed and associated movements in participants aged 5 to 18 years for age, sex, and laterality. Ten motor tasks of the Zurich Neuromotor Assessment (repetitive and alternating movements of hands and feet, repetitive and sequential finger movements, the pegboard, static and dynamic balance, diadochokinesis) were administered to 593 right-handed participants (286 males, 307 females). A strong improvement with age was observed in motor speed from age 5 to 10, followed by a levelling-off between 12 and 18 years. Simple tasks and the pegboard matured early and complex tasks later. Simple tasks showed no associated movements beyond early childhood; in complex tasks associated movements persisted until early adulthood. The two sexes differed only marginally in speed, but markedly in associated movements. A significant laterality (p<0.001) in speed was found for all tasks except for static balance; the pegboard was most lateralized, and sequential finger movements least. Associated movements were lateralized only for a few complex tasks. We also noted a substantial interindividual variability. Motor speed and associated movements improve strongly in childhood, weakly in adolescence, and are both of developmental relevance. Because they correlate weakly, they provide complementary information.

Enhanced and diminished visuo-spatial information processing in autism depends on stimulus complexity.

PubMed

Bertone, Armando; Mottron, Laurent; Jelenic, Patricia; Faubert, Jocelyn

2005-10-01

Visuo-perceptual processing in autism is characterized by intact or enhanced performance on static spatial tasks and inferior performance on dynamic tasks, suggesting a deficit of dorsal visual stream processing in autism. However, previous findings by Bertone et al. indicate that neuro-integrative mechanisms used to detect complex motion, rather than motion perception per se, may be impaired in autism. We present here the first demonstration of concurrent enhanced and decreased performance in autism on the same visuo-spatial static task, wherein the only factor dichotomizing performance was the neural complexity required to discriminate grating orientation. The ability of persons with autism was found to be superior for identifying the orientation of simple, luminance-defined (or first-order) gratings but inferior for complex, texture-defined (or second-order) gratings. Using a flicker contrast sensitivity task, we demonstrated that this finding is probably not due to abnormal information processing at a sub-cortical level (magnocellular and parvocellular functioning). Together, these findings are interpreted as a clear indication of altered low-level perceptual information processing in autism, and confirm that the deficits and assets observed in autistic visual perception are contingent on the complexity of the neural network required to process a given type of visual stimulus. We suggest that atypical neural connectivity, resulting in enhanced lateral inhibition, may account for both enhanced and decreased low-level information processing in autism.

MUSIC-Expected maximization gaussian mixture methodology for clustering and detection of task-related neuronal firing rates.

PubMed

Ortiz-Rosario, Alexis; Adeli, Hojjat; Buford, John A

2017-01-15

Researchers often rely on simple methods to identify involvement of neurons in a particular motor task. The historical approach has been to inspect large groups of neurons and subjectively separate neurons into groups based on the expertise of the investigator. In cases where neuron populations are small it is reasonable to inspect these neuronal recordings and their firing rates carefully to avoid data omissions. In this paper, a new methodology is presented for automatic objective classification of neurons recorded in association with behavioral tasks into groups. By identifying characteristics of neurons in a particular group, the investigator can then identify functional classes of neurons based on their relationship to the task. The methodology is based on integration of a multiple signal classification (MUSIC) algorithm to extract relevant features from the firing rate and an expectation-maximization Gaussian mixture algorithm (EM-GMM) to cluster the extracted features. The methodology is capable of identifying and clustering similar firing rate profiles automatically based on specific signal features. An empirical wavelet transform (EWT) was used to validate the features found in the MUSIC pseudospectrum and the resulting signal features captured by the methodology. Additionally, this methodology was used to inspect behavioral elements of neurons to physiologically validate the model. This methodology was tested using a set of data collected from awake behaving non-human primates. Copyright © 2016 Elsevier B.V. All rights reserved.

Flexibility in Visual Working Memory: Accurate Change Detection in the Face of Irrelevant Variations in Position

PubMed Central

Woodman, Geoffrey F.; Vogel, Edward K.; Luck, Steven J.

2012-01-01

Many recent studies of visual working memory have used change-detection tasks in which subjects view sequential displays and are asked to report whether they are identical or if one object has changed. A key question is whether the memory system used to perform this task is sufficiently flexible to detect changes in object identity independent of spatial transformations, but previous research has yielded contradictory results. To address this issue, the present study compared standard change-detection tasks with tasks in which the objects varied in size or position between successive arrays. Performance was nearly identical across the standard and transformed tasks unless the task implicitly encouraged spatial encoding. These results resolve the discrepancies in prior studies and demonstrate that the visual working memory system can detect changes in object identity across spatial transformations. PMID:22287933

The Hebb repetition effect in simple and complex memory span.

PubMed

Oberauer, Klaus; Jones, Timothy; Lewandowsky, Stephan

2015-08-01

The Hebb repetition effect refers to the finding that immediate serial recall is improved over trials for memory lists that are surreptitiously repeated across trials, relative to new lists. We show in four experiments that the Hebb repetition effect is also observed with a complex-span task, in which encoding or retrieval of list items alternates with an unrelated processing task. The interruption of encoding or retrieval by the processing task did not reduce the size of the Hebb effect, demonstrating that incidental long-term learning forms integrated representations of lists, excluding the interleaved processing events. Contrary to the assumption that complex-span performance relies more on long-term memory than standard immediate serial recall (simple span), the Hebb effect was not larger in complex-span than in simple-span performance. The Hebb effect in complex span was also not modulated by the opportunity for refreshing list items, questioning a role of refreshing for the acquisition of the long-term memory representations underlying the effect.

Differential recall of derived and inflected word forms in working memory: examining the role of morphological information in simple and complex working memory tasks

PubMed Central

Service, Elisabet; Maury, Sini

2015-01-01

Working memory (WM) has been described as an interface between cognition and action, or a system for access to a limited amount of information needed in complex cognition. Access to morphological information is needed for comprehending and producing sentences. The present study probed WM for morphologically complex word forms in Finnish, a morphologically rich language. We studied monomorphemic (boy), inflected (boy+’s), and derived (boy+hood) words in three tasks. Simple span, immediate serial recall of words, in Experiment 1, is assumed to mainly rely on information in the focus of attention. Sentence span, a dual task combining sentence reading with recall of the last word (Experiment 2) or of a word not included in the sentence (Experiment 3) is assumed to involve establishment of a search set in long-term memory for fast activation into the focus of attention. Recall was best for monomorphemic and worst for inflected word forms with performance on derived words in between. However, there was an interaction between word type and experiment, suggesting that complex span is more sensitive to morphological complexity in derivations than simple span. This was explored in a within-subjects Experiment 4 combining all three tasks. An interaction between morphological complexity and task was replicated. Both inflected and derived forms increased load in WM. In simple span, recall of inflectional forms resulted in form errors. Complex span tasks were more sensitive to morphological load in derived words, possibly resulting from interference from morphological neighbors in the mental lexicon. The results are best understood as involving competition among inflectional forms when binding words from input into an output structure, and competition from morphological neighbors in secondary memory during cumulative retrieval-encoding cycles. Models of verbal recall need to be able to represent morphological as well as phonological and semantic information. PMID:25642181

A Feasibility Study for Perioperative Ventricular Tachycardia Prognosis and Detection and Noise Detection Using a Neural Network and Predictive Linear Operators

NASA Technical Reports Server (NTRS)

Moebes, T. A.

1994-01-01

To locate the accessory pathway(s) in preexicitation syndromes, epicardial and endocardial ventricular mapping is performed during anterograde ventricular activation via accessory pathway(s) from data originally received in signal form. As the number of channels increases, it is pertinent that more automated detection of coherent/incoherent signals is achieved as well as the prediction and prognosis of ventricular tachywardia (VT). Today's computers and computer program algorithms are not good in simple perceptual tasks such as recognizing a pattern or identifying a sound. This discrepancy, among other things, has been a major motivating factor in developing brain-based, massively parallel computing architectures. Neural net paradigms have proven to be effective at pattern recognition tasks. In signal processing, the picking of coherent/incoherent signals represents a pattern recognition task for computer systems. The picking of signals representing the onset ot VT also represents such a computer task. We attacked this problem by defining four signal attributes for each potential first maximal arrival peak and one signal attribute over the entire signal as input to a back propagation neural network. One attribute was the predicted amplitude value after the maximum amplitude over a data window. Then, by using a set of known (user selected) coherent/incoherent signals, and signals representing the onset of VT, we trained the back propagation network to recognize coherent/incoherent signals, and signals indicating the onset of VT. Since our output scheme involves a true or false decision, and since the output unit computes values between 0 and 1, we used a Fuzzy Arithmetic approach to classify data as coherent/incoherent signals. Furthermore, a Mean-Square Error Analysis was used to determine system stability. The neural net based picking coherent/incoherent signal system achieved high accuracy on picking coherent/incoherent signals on different patients. The system also achieved a high accuracy of picking signals which represent the onset of VT, that is, VT immediately followed these signals. A special binary representation of the input and output data allowed the neural network to train very rapidly as compared to another standard decimal or normalized representations of the data.

Representation of limb kinematics in Purkinje cell simple spike discharge is conserved across multiple tasks.

PubMed

Hewitt, Angela L; Popa, Laurentiu S; Pasalar, Siavash; Hendrix, Claudia M; Ebner, Timothy J

2011-11-01

Encoding of movement kinematics in Purkinje cell simple spike discharge has important implications for hypotheses of cerebellar cortical function. Several outstanding questions remain regarding representation of these kinematic signals. It is uncertain whether kinematic encoding occurs in unpredictable, feedback-dependent tasks or kinematic signals are conserved across tasks. Additionally, there is a need to understand the signals encoded in the instantaneous discharge of single cells without averaging across trials or time. To address these questions, this study recorded Purkinje cell firing in monkeys trained to perform a manual random tracking task in addition to circular tracking and center-out reach. Random tracking provides for extensive coverage of kinematic workspaces. Direction and speed errors are significantly greater during random than circular tracking. Cross-correlation analyses comparing hand and target velocity profiles show that hand velocity lags target velocity during random tracking. Correlations between simple spike firing from 120 Purkinje cells and hand position, velocity, and speed were evaluated with linear regression models including a time constant, τ, as a measure of the firing lead/lag relative to the kinematic parameters. Across the population, velocity accounts for the majority of simple spike firing variability (63 ± 30% of R(adj)(2)), followed by position (28 ± 24% of R(adj)(2)) and speed (11 ± 19% of R(adj)(2)). Simple spike firing often leads hand kinematics. Comparison of regression models based on averaged vs. nonaveraged firing and kinematics reveals lower R(adj)(2) values for nonaveraged data; however, regression coefficients and τ values are highly similar. Finally, for most cells, model coefficients generated from random tracking accurately estimate simple spike firing in either circular tracking or center-out reach. These findings imply that the cerebellum controls movement kinematics, consistent with a forward internal model that predicts upcoming limb kinematics.

Brain blood flow changes measured by positron emission tomography during an auditory cognitive task in healthy volunteers and in schizophrenic patients.

PubMed

Emri, Miklós; Glaub, Teodóra; Berecz, Roland; Lengyel, Zsolt; Mikecz, Pál; Repa, Imre; Bartók, Eniko; Degrell, István; Trón, Lajos

2006-05-01

Cognitive deficit is an essential feature of schizophrenia. One of the generally used simple cognitive tasks to characterize specific cognitive dysfunctions is the auditory "oddball" paradigm. During this task, two different tones are presented with different repetition frequencies and the subject is asked to pay attention and to respond to the less frequent tone. The aim of the present study was to apply positron emission tomography (PET) to measure the regional brain blood flow changes induced by an auditory oddball task in healthy volunteers and in stable schizophrenic patients in order to detect activation differences between the two groups. Eight healthy volunteers and 11 schizophrenic patients were studied. The subjects carried out a specific auditory oddball task, while cerebral activation measured via the regional distribution of [15O]-butanol activity changes in the PET camera was recorded. Task-related activation differed significantly across the patients and controls. The healthy volunteers displayed significant activation in the anterior cingulate area (Brodman Area - BA32), while in the schizophrenic patients the area was wider, including the mediofrontal regions (BA32 and BA10). The distance between the locations of maximal activation of the two populations were 33 mm and the cluster size was about twice as large in the patient group. The present results demonstrate that the perfusion changes induced in the schizophrenic patients by this cognitive task extends over a larger part of the mediofrontal cortex than in the healthy volunteers. The different pattern of activation observed during the auditory oddball task in the schizophrenic patients suggests that a larger cortical area - and consequently a larger variety of neuronal networks--is involved in the cognitive processes in these patients. The dispersion of stimulus processing during a cognitive task requiring sustained attention and stimulus discrimination may play an important role in the pathomechanism of the disorder.

SOAR: An Architecture for General Intelligence

DTIC Science & Technology

1987-12-01

these tasks, and (3) learn about all aspects of the tasks and its performance on them. Soar has existed since mid 1982 as an experimental software system...intelligence. Soar’s behavior has already been studied over a range of tasks and methods (Figure 1), which sample its intended range, though...in multiple small tasks: Generate and test, AND/OR search, hill climbing ( simple and steepest-ascent), means-ends analysis, operator subgoaling

Lifelong Transfer Learning for Heterogeneous Teams of Agents in Sequential Decision Processes

DTIC Science & Technology

2016-06-01

making (SDM) tasks in dynamic environments with simulated and physical robots . 15. SUBJECT TERMS Sequential decision making, lifelong learning, transfer...sequential decision-making (SDM) tasks in dynamic environments with both simple benchmark tasks and more complex aerial and ground robot tasks. Our work...and ground robots in the presence of disturbances: We applied our methods to the problem of learning controllers for robots with novel disturbances in

Poststimulation time interval-dependent effects of motor cortex anodal tDCS on reaction-time task performance.

PubMed

Molero-Chamizo, Andrés; Alameda Bailén, José R; Garrido Béjar, Tamara; García López, Macarena; Jaén Rodríguez, Inmaculada; Gutiérrez Lérida, Carolina; Pérez Panal, Silvia; González Ángel, Gloria; Lemus Corchero, Laura; Ruiz Vega, María J; Nitsche, Michael A; Rivera-Urbina, Guadalupe N

2018-02-01

Anodal transcranial direct current stimulation (tDCS) induces long-term potentiation-like plasticity, which is associated with long-lasting effects on different cognitive, emotional, and motor performances. Specifically, tDCS applied over the motor cortex is considered to improve reaction time in simple and complex tasks. The timing of tDCS relative to task performance could determine the efficacy of tDCS to modulate performance. The aim of this study was to compare the effects of a single session of anodal tDCS (1.5 mA, for 15 min) applied over the left primary motor cortex (M1) versus sham stimulation on performance of a go/no-go simple reaction-time task carried out at three different time points after tDCS-namely, 0, 30, or 60 min after stimulation. Performance zero min after anodal tDCS was improved during the whole course of the task. Performance 30 min after anodal tDCS was improved only in the last block of the reaction-time task. Performance 60 min after anodal tDCS was not significantly different throughout the entire task. These findings suggest that the motor cortex excitability changes induced by tDCS can improve motor responses, and these effects critically depend on the time interval between stimulation and task performance.

Use of the Hotelling observer to optimize image reconstruction in digital breast tomosynthesis

PubMed Central

Sánchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan

2015-01-01

Abstract. We propose an implementation of the Hotelling observer that can be applied to the optimization of linear image reconstruction algorithms in digital breast tomosynthesis. The method is based on considering information within a specific region of interest, and it is applied to the optimization of algorithms for detectability of microcalcifications. Several linear algorithms are considered: simple back-projection, filtered back-projection, back-projection filtration, and Λ-tomography. The optimized algorithms are then evaluated through the reconstruction of phantom data. The method appears robust across algorithms and parameters and leads to the generation of algorithm implementations which subjectively appear optimized for the task of interest. PMID:26702408

Plasmonic computing of spatial differentiation

NASA Astrophysics Data System (ADS)

Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

2017-05-01

Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

Can Youthful Students be Encouraged to Self-repair Damaged Vision Using Elementary Mathematics and Physics Principles?

NASA Astrophysics Data System (ADS)

Ferreira, Nadja; McLeod, Roger

2006-03-01

Safe and easy self-repair of damaged vision in youth, detected from squinted eyes, motivated by simple applied math and physics, and over-stretched elastics. Parental permission and participation, with math skills of numerical cancellation, bring physics understanding to students. They recognize pupil diameter changes with light intensity. Ideas of focal surfaces and wavelength dependence can be achieved by burning paper with a magnifying glass, and dispersing light with a prism. Safeness of eye and head movements required are like those of the mother in applying makeup, or of a father in shaving. Easily defined, performed and monitored visual tasks can complete the repair(s).

Cultural influences on neural substrates of attentional control.

PubMed

Hedden, Trey; Ketay, Sarah; Aron, Arthur; Markus, Hazel Rose; Gabrieli, John D E

2008-01-01

Behavioral research has shown that people from Western cultural contexts perform better on tasks emphasizing independent (absolute) dimensions than on tasks emphasizing interdependent (relative) dimensions, whereas the reverse is true for people from East Asian contexts. We assessed functional magnetic resonance imaging responses during performance of simple visuospatial tasks in which participants made absolute judgments (ignoring visual context) or relative judgments (taking visual context into account). In each group, activation in frontal and parietal brain regions known to be associated with attentional control was greater during culturally nonpreferred judgments than during culturally preferred judgments. Also, within each group, activation differences in these regions correlated strongly with scores on questionnaires measuring individual differences in culture-typical identity. Thus, the cultural background of an individual and the degree to which the individual endorses cultural values moderate activation in brain networks engaged during even simple visual and attentional tasks.

FRaC: a feature-modeling approach for semi-supervised and unsupervised anomaly detection.

PubMed

Noto, Keith; Brodley, Carla; Slonim, Donna

2012-01-01

Anomaly detection involves identifying rare data instances (anomalies) that come from a different class or distribution than the majority (which are simply called "normal" instances). Given a training set of only normal data, the semi-supervised anomaly detection task is to identify anomalies in the future. Good solutions to this task have applications in fraud and intrusion detection. The unsupervised anomaly detection task is different: Given unlabeled, mostly-normal data, identify the anomalies among them. Many real-world machine learning tasks, including many fraud and intrusion detection tasks, are unsupervised because it is impractical (or impossible) to verify all of the training data. We recently presented FRaC, a new approach for semi-supervised anomaly detection. FRaC is based on using normal instances to build an ensemble of feature models, and then identifying instances that disagree with those models as anomalous. In this paper, we investigate the behavior of FRaC experimentally and explain why FRaC is so successful. We also show that FRaC is a superior approach for the unsupervised as well as the semi-supervised anomaly detection task, compared to well-known state-of-the-art anomaly detection methods, LOF and one-class support vector machines, and to an existing feature-modeling approach.

FRaC: a feature-modeling approach for semi-supervised and unsupervised anomaly detection

PubMed Central

Brodley, Carla; Slonim, Donna

2011-01-01

Anomaly detection involves identifying rare data instances (anomalies) that come from a different class or distribution than the majority (which are simply called “normal” instances). Given a training set of only normal data, the semi-supervised anomaly detection task is to identify anomalies in the future. Good solutions to this task have applications in fraud and intrusion detection. The unsupervised anomaly detection task is different: Given unlabeled, mostly-normal data, identify the anomalies among them. Many real-world machine learning tasks, including many fraud and intrusion detection tasks, are unsupervised because it is impractical (or impossible) to verify all of the training data. We recently presented FRaC, a new approach for semi-supervised anomaly detection. FRaC is based on using normal instances to build an ensemble of feature models, and then identifying instances that disagree with those models as anomalous. In this paper, we investigate the behavior of FRaC experimentally and explain why FRaC is so successful. We also show that FRaC is a superior approach for the unsupervised as well as the semi-supervised anomaly detection task, compared to well-known state-of-the-art anomaly detection methods, LOF and one-class support vector machines, and to an existing feature-modeling approach. PMID:22639542

Mining Tasks from the Web Anchor Text Graph: MSR Notebook Paper for the TREC 2015 Tasks Track

DTIC Science & Technology

2015-11-20

Mining Tasks from the Web Anchor Text Graph: MSR Notebook Paper for the TREC 2015 Tasks Track Paul N. Bennett Microsoft Research Redmond, USA pauben...anchor text graph has proven useful in the general realm of query reformulation [2], we sought to quantify the value of extracting key phrases from...anchor text in the broader setting of the task understanding track. Given a query, our approach considers a simple method for identifying a relevant

Drawing Firmer Conclusions: Autistic Children Show No Evidence of a Local Processing Bias in a Controlled Copying Task

ERIC Educational Resources Information Center

Smith, Alastair D.; Kenny, Lorcan; Rudnicka, Anna; Briscoe, Josie; Pellicano, Elizabeth

2016-01-01

Drawing tasks are frequently used to test competing theories of visuospatial skills in autism. Yet, methodological differences between studies have led to inconsistent findings. To distinguish between accounts based on local bias or global deficit, we present a simple task that has previously revealed dissociable local/global impairments in…

Problem Solving vs. Troubleshooting Tasks: The Case of Sixth-Grade Students Studying Simple Electric Circuits

ERIC Educational Resources Information Center

Safadi, Rafi'; Yerushalmi, Edit

2014-01-01

We compared the materialization of knowledge integration processes in class discussions that followed troubleshooting (TS) and problem-solving (PS) tasks and examined the impact of these tasks on students' conceptual understanding. The study was conducted in two sixth-grade classes taught by the same teacher, in six lessons that constituted a…

Perceived Difficulty of a Motor-Skill Task as a Function of Training.

ERIC Educational Resources Information Center

Bratfisch, Oswald; And Others

A simple device called a "wire labyrinth" was used in an experiment involving learning of a two-hand motor task. The Ss were asked, after completing each of 7 successive trails, to give their estimates of perceived (subjective) difficulty of the task. For this purpose, the psychophysical method of magnitude estimation was used. Time was…

Working Memory Deficits in Children with Reading Difficulties: Memory Span and Dual Task Coordination

ERIC Educational Resources Information Center

Wang, Shinmin; Gathercole, Susan E.

2013-01-01

The current study investigated the cause of the reported problems in working memory in children with reading difficulties. Verbal and visuospatial simple and complex span tasks, and digit span and reaction times tasks performed singly and in combination, were administered to 46 children with single word reading difficulties and 45 typically…

Visuospatial Working Memory in Intuitive Geometry, and in Academic Achievement in Geometry

ERIC Educational Resources Information Center

Giofre, David; Mammarella, Irene C.; Ronconi, Lucia; Cornoldi, Cesare

2013-01-01

A study was conducted on the involvement of visuospatial working memory (VSWM) in intuitive geometry and in school performance in geometry at secondary school. A total of 166 pupils were administered: (1) six VSWM tasks, comprising simple storage and complex span tasks; and (2) the intuitive geometry task devised by Dehaene, Izard, Pica, and…

Heritability of Cognitive Abilities as Measured by Mental Chronometric Tasks: A Meta-Analysis

ERIC Educational Resources Information Center

Beaujean, A.A.

2005-01-01

The purpose of this study is to meta-analyze the published studies that measure the performance differences in mental chronometric tasks using a behavioral genetic research design. Because chronometric tasks are so simple, individual differences in the time it takes to complete them are largely due to underlying biological and physiological…

Part-task vs. whole-task training on a supervisory control task

NASA Technical Reports Server (NTRS)

Battiste, Vernol

1987-01-01

The efficacy of a part-task training for the psychomotor portion of a supervisory control simulation was compared to that of the whole-task training, using six subjects in each group, who were asked to perform a task as quickly as possible. Part-task training was provided with the cursor-control device prior to transition to the whole-task. The analysis of both the training and experimental trials demonstrated a significant performance advantage for the part-task group: the tasks were performed better and at higher speed. Although the subjects finally achieved the same level of performance in terms of score, the part-task method was preferable for economic reasons, since simple pretraining systems are significantly less expensive than the whole-task training systems.

Mental and psychomotor task performance in noise

NASA Technical Reports Server (NTRS)

1984-01-01

The possible adverse effects of noise on mental and psychomotor task performance were a matter of practical concern for centuries and continue to be a matter of scientific controversy. A review indicates that except for the masking or interferences with the hearing of sounds needed to perform a given task, noise does not necessarily interfer with work performance. However, because of difficulties in the experimental control of some of these possible effects, the results of research on work performance in noise were inconsistent and difficult to encompass in any simple theoretical construct. Indeed, reviews of research in this area conclude that simple generalizations about possible effects of noise on work performance cannot be made. Nevertheless, several general theories were put forth.

Simple, efficient allocation of modelling runs on heterogeneous clusters with MPI

USGS Publications Warehouse

Donato, David I.

2017-01-01

In scientific modelling and computation, the choice of an appropriate method for allocating tasks for parallel processing depends on the computational setting and on the nature of the computation. The allocation of independent but similar computational tasks, such as modelling runs or Monte Carlo trials, among the nodes of a heterogeneous computational cluster is a special case that has not been specifically evaluated previously. A simulation study shows that a method of on-demand (that is, worker-initiated) pulling from a bag of tasks in this case leads to reliably short makespans for computational jobs despite heterogeneity both within and between cluster nodes. A simple reference implementation in the C programming language with the Message Passing Interface (MPI) is provided.

Beyond simple charts: Design of visualizations for big health data

PubMed Central

Ola, Oluwakemi; Sedig, Kamran

2016-01-01

Health data is often big data due to its high volume, low veracity, great variety, and high velocity. Big health data has the potential to improve productivity, eliminate waste, and support a broad range of tasks related to disease surveillance, patient care, research, and population health management. Interactive visualizations have the potential to amplify big data’s utilization. Visualizations can be used to support a variety of tasks, such as tracking the geographic distribution of diseases, analyzing the prevalence of disease, triaging medical records, predicting outbreaks, and discovering at-risk populations. Currently, many health visualization tools use simple charts, such as bar charts and scatter plots, that only represent few facets of data. These tools, while beneficial for simple perceptual and cognitive tasks, are ineffective when dealing with more complex sensemaking tasks that involve exploration of various facets and elements of big data simultaneously. There is need for sophisticated and elaborate visualizations that encode many facets of data and support human-data interaction with big data and more complex tasks. When not approached systematically, design of such visualizations is labor-intensive, and the resulting designs may not facilitate big-data-driven tasks. Conceptual frameworks that guide the design of visualizations for big data can make the design process more manageable and result in more effective visualizations. In this paper, we demonstrate how a framework-based approach can help designers create novel, elaborate, non-trivial visualizations for big health data. We present four visualizations that are components of a larger tool for making sense of large-scale public health data. PMID:28210416

Beyond simple charts: Design of visualizations for big health data.

PubMed

Ola, Oluwakemi; Sedig, Kamran

2016-01-01

Health data is often big data due to its high volume, low veracity, great variety, and high velocity. Big health data has the potential to improve productivity, eliminate waste, and support a broad range of tasks related to disease surveillance, patient care, research, and population health management. Interactive visualizations have the potential to amplify big data's utilization. Visualizations can be used to support a variety of tasks, such as tracking the geographic distribution of diseases, analyzing the prevalence of disease, triaging medical records, predicting outbreaks, and discovering at-risk populations. Currently, many health visualization tools use simple charts, such as bar charts and scatter plots, that only represent few facets of data. These tools, while beneficial for simple perceptual and cognitive tasks, are ineffective when dealing with more complex sensemaking tasks that involve exploration of various facets and elements of big data simultaneously. There is need for sophisticated and elaborate visualizations that encode many facets of data and support human-data interaction with big data and more complex tasks. When not approached systematically, design of such visualizations is labor-intensive, and the resulting designs may not facilitate big-data-driven tasks. Conceptual frameworks that guide the design of visualizations for big data can make the design process more manageable and result in more effective visualizations. In this paper, we demonstrate how a framework-based approach can help designers create novel, elaborate, non-trivial visualizations for big health data. We present four visualizations that are components of a larger tool for making sense of large-scale public health data.

Efficiency of the human observer detecting random signals in random backgrounds

PubMed Central

Park, Subok; Clarkson, Eric; Kupinski, Matthew A.; Barrett, Harrison H.

2008-01-01

The efficiencies of the human observer and the channelized-Hotelling observer relative to the ideal observer for signal-detection tasks are discussed. Both signal-known-exactly (SKE) tasks and signal-known-statistically (SKS) tasks are considered. Signal location is uncertain for the SKS tasks, and lumpy backgrounds are used for background uncertainty in both cases. Markov chain Monte Carlo methods are employed to determine ideal-observer performance on the detection tasks. Psychophysical studies are conducted to compute human-observer performance on the same tasks. Efficiency is computed as the squared ratio of the detectabilities of the observer of interest to the ideal observer. Human efficiencies are approximately 2.1% and 24%, respectively, for the SKE and SKS tasks. The results imply that human observers are not affected as much as the ideal observer by signal-location uncertainty even though the ideal observer outperforms the human observer for both tasks. Three different simplified pinhole imaging systems are simulated, and the humans and the model observers rank the systems in the same order for both the SKE and the SKS tasks. PMID:15669610

Dedicated memory structure holding data for detecting available worker thread(s) and informing available worker thread(s) of task(s) to execute

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

Chiu, George L.; Eichenberger, Alexandre E.; O'Brien, John K. P.

The present disclosure relates generally to a dedicated memory structure (that is, hardware device) holding data for detecting available worker thread(s) and informing available worker thread(s) of task(s) to execute.

Detection of deception: Event-related potential markers of attention and cognitive control during intentional false responses.

PubMed

Gibbons, Henning; Schnuerch, Robert; Wittinghofer, Christina; Armbrecht, Anne-Simone; Stahl, Jutta

2018-06-01

Successful deception requires the coordination of multiple mental processes, such as attention, conflict monitoring, and the regulation of emotion. We employed a simple classification task, assessing ERPs to further investigate the attentional and cognitive control components of (instructed) deception. In Experiment 1, 20 participants repeatedly categorized visually presented names of five animals and five plants. Prior to the experiment, however, each participant covertly selected one animal and one plant for deliberate misclassification. For these critical items, we observed significantly increased response times (RTs), error rates, and amplitudes of three ERP components: anterior P3a indicating the processing of task relevance, medial-frontal negativity reflecting conflict monitoring, and posterior P3b indicating sustained visual attention. In a blind identification of the individual critical words based on a priori defined criteria, an algorithm using two behavioral and two ERP measures combined showed a sensitivity of 0.73 and a specificity of 0.95, thus performing far above chance (0.2/0.2). Experiment 2 used five clothing and five furniture names and successfully replicated the findings of Experiment 1 in 25 new participants. For detection of the critical words, the algorithm from Experiment 1 was reused with only slight adjustments of the ERP time windows. This resulted in a very high detection performance (sensitivity 0.88, specificity 0.94) and significantly outperformed an algorithm based on RT alone. Thus, at least under controlled laboratory conditions, a highly accurate detection of instructed lies via the attentional and cognitive control components is feasible, and benefits strongly from combined behavioral and ERP measures. © 2017 Society for Psychophysiological Research.

Brain activity during auditory and visual phonological, spatial and simple discrimination tasks.

PubMed

Salo, Emma; Rinne, Teemu; Salonen, Oili; Alho, Kimmo

2013-02-16

We used functional magnetic resonance imaging to measure human brain activity during tasks demanding selective attention to auditory or visual stimuli delivered in concurrent streams. Auditory stimuli were syllables spoken by different voices and occurring in central or peripheral space. Visual stimuli were centrally or more peripherally presented letters in darker or lighter fonts. The participants performed a phonological, spatial or "simple" (speaker-gender or font-shade) discrimination task in either modality. Within each modality, we expected a clear distinction between brain activations related to nonspatial and spatial processing, as reported in previous studies. However, within each modality, different tasks activated largely overlapping areas in modality-specific (auditory and visual) cortices, as well as in the parietal and frontal brain regions. These overlaps may be due to effects of attention common for all three tasks within each modality or interaction of processing task-relevant features and varying task-irrelevant features in the attended-modality stimuli. Nevertheless, brain activations caused by auditory and visual phonological tasks overlapped in the left mid-lateral prefrontal cortex, while those caused by the auditory and visual spatial tasks overlapped in the inferior parietal cortex. These overlapping activations reveal areas of multimodal phonological and spatial processing. There was also some evidence for intermodal attention-related interaction. Most importantly, activity in the superior temporal sulcus elicited by unattended speech sounds was attenuated during the visual phonological task in comparison with the other visual tasks. This effect might be related to suppression of processing irrelevant speech presumably distracting the phonological task involving the letters. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

Response competition and response inhibition during different choice-discrimination tasks: evidence from ERP measured inside MRI scanner.

PubMed

Gonzalez-Rosa, Javier J; Inuggi, Alberto; Blasi, Valeria; Cursi, Marco; Annovazzi, Pietro; Comi, Giancarlo; Falini, Andrea; Leocani, Letizia

2013-07-01

We investigated the neural correlates underlying response inhibition and conflict detection processes using ERPs and source localization analyses simultaneously acquired during fMRI scanning. ERPs were elicited by a simple reaction time task (SRT), a Go/NoGo task, and a Stroop-like task (CST). The cognitive conflict was thus manipulated in order to probe the degree to which information processing is shared across cognitive systems. We proposed to dissociate inhibition and interference conflict effects on brain activity by using identical Stroop-like congruent/incongruent stimuli in all three task contexts and while varying the response required. NoGo-incongruent trials showed a larger N2 and enhanced activations of rostral anterior cingulate cortex (ACC) and pre-supplementary motor area, whereas Go-congruent trials showed a larger P3 and increased parietal activations. Congruent and incongruent conditions of the CST task also elicited similar N2, P3 and late negativity (LN) ERPs, though CST-incongruent trials revealed a larger LN and enhanced prefrontal and ACC activations. Considering the stimulus probability and experimental manipulation of our study, current findings suggest that NoGo N2 and frontal NoGo P3 appear to be more associated to response inhibition rather than a specific conflict monitoring, whereas occipito-parietal P3 of Go and CST conditions may be more linked to a planned response competition between the prepared and required response. LN, however, appears to be related to higher level conflict monitoring associated with response choice-discrimination but not when the presence of cognitive conflict is associated with response inhibition. Copyright © 2013. Published by Elsevier B.V.

Interval Timing Deficits Assessed by Time Reproduction Dual Tasks as Cognitive Endophenotypes for Attention-Deficit/Hyperactivity Disorder

PubMed Central

Hwang-Gu, Shoou-Lian; Gau, Susan Shur-Fen

2015-01-01

The literature has suggested timing processing as a potential endophenotype for attention deficit/hyperactivity disorder (ADHD); however, whether the subjective internal clock speed presented by verbal estimation and limited attention capacity presented by time reproduction could be endophenotypes for ADHD is still unknown. We assessed 223 youths with DSM-IV ADHD (age range: 10-17 years), 105 unaffected siblings, and 84 typically developing (TD) youths using psychiatric interviews, intelligence tests, verbal estimation and time reproduction tasks (single task and simple and difficult dual tasks) at 5-second, 12-second, and 17-second intervals. We found that youths with ADHD tended to overestimate time in verbal estimation more than their unaffected siblings and TD youths, implying that fast subjective internal clock speed might be a characteristic of ADHD, rather than an endophenotype for ADHD. Youths with ADHD and their unaffected siblings were less precise in time reproduction dual tasks than TD youths. The magnitude of estimated errors in time reproduction was greater in youths with ADHD and their unaffected siblings than in TD youths, with an increased time interval at the 17-second interval and with increased task demands on both simple and difficult dual tasks versus the single task. Increased impaired time reproduction in dual tasks with increased intervals and task demands were shown in youths with ADHD and their unaffected siblings, suggesting that time reproduction deficits explained by limited attention capacity might be a useful endophenotype of ADHD. PMID:25992899

Working Memory Training Improves Dual-Task Performance on Motor Tasks.

PubMed

Kimura, Takehide; Kaneko, Fuminari; Nagahata, Keita; Shibata, Eriko; Aoki, Nobuhiro

2017-01-01

The authors investigated whether working memory training improves motor-motor dual-task performance consisted of upper and lower limb tasks. The upper limb task was a simple reaction task and the lower limb task was an isometric knee extension task. 45 participants (age = 21.8 ± 1.6 years) were classified into a working memory training group (WM-TRG), dual-task training group, or control group. The training duration was 2 weeks (15 min, 4 times/week). Our results indicated that working memory capacity increased significantly only in the WM-TRG. Dual-task performance improved in the WM-TRG and dual-task training group. Our study provides the novel insight that working memory training improves dual-task performance without specific training on the target motor task.

Rendering visual events as sounds: Spatial attention capture by auditory augmented reality.

PubMed

Stone, Scott A; Tata, Matthew S

2017-01-01

Many salient visual events tend to coincide with auditory events, such as seeing and hearing a car pass by. Information from the visual and auditory senses can be used to create a stable percept of the stimulus. Having access to related coincident visual and auditory information can help for spatial tasks such as localization. However not all visual information has analogous auditory percepts, such as viewing a computer monitor. Here, we describe a system capable of detecting and augmenting visual salient events into localizable auditory events. The system uses a neuromorphic camera (DAVIS 240B) to detect logarithmic changes of brightness intensity in the scene, which can be interpreted as salient visual events. Participants were blindfolded and asked to use the device to detect new objects in the scene, as well as determine direction of motion for a moving visual object. Results suggest the system is robust enough to allow for the simple detection of new salient stimuli, as well accurately encoding direction of visual motion. Future successes are probable as neuromorphic devices are likely to become faster and smaller in the future, making this system much more feasible.

Rendering visual events as sounds: Spatial attention capture by auditory augmented reality

PubMed Central

Tata, Matthew S.

2017-01-01

Many salient visual events tend to coincide with auditory events, such as seeing and hearing a car pass by. Information from the visual and auditory senses can be used to create a stable percept of the stimulus. Having access to related coincident visual and auditory information can help for spatial tasks such as localization. However not all visual information has analogous auditory percepts, such as viewing a computer monitor. Here, we describe a system capable of detecting and augmenting visual salient events into localizable auditory events. The system uses a neuromorphic camera (DAVIS 240B) to detect logarithmic changes of brightness intensity in the scene, which can be interpreted as salient visual events. Participants were blindfolded and asked to use the device to detect new objects in the scene, as well as determine direction of motion for a moving visual object. Results suggest the system is robust enough to allow for the simple detection of new salient stimuli, as well accurately encoding direction of visual motion. Future successes are probable as neuromorphic devices are likely to become faster and smaller in the future, making this system much more feasible. PMID:28792518

Unexpected acoustic stimulation during action preparation reveals gradual re-specification of movement direction.

PubMed

Marinovic, Welber; Tresilian, James; Chapple, Jack L; Riek, Stephan; Carroll, Timothy J

2017-04-21

A loud acoustic stimulus (LAS) is often used as a tool to investigate motor preparation in simple reaction time (RT) tasks, where all movement parameters are known in advance. In this report, we used a LAS to examine direction specification in simple and choice RT tasks. This allowed us to investigate how the specification of movement direction unfolds during the preparation period. In two experiments, participants responded to the appearance of an imperative stimulus (IS) with a ballistic wrist force directed toward one of two targets. In probe trials, a LAS (120dBa) was delivered around the time of IS presentation. In Experiment 1, RTs in the simple RT task were faster when the LAS was presented, but the effect on the movement kinematics was negligible. In the Choice RT task, however, movement direction variability increased when the LAS was presented. In Experiment 2, when we primed movements toward one direction, our analyses revealed that the longer participants took to start a movement, the more accurate their responses became. Our results show not only that movement direction reprogramming occurs quickly and continuously, but also that LAS can be a valuable tool to obtain meaningful readouts of the motor system's preparatory state. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

The paradoxical effect of long instructions on negative affect and performance: When, for whom and why do they backfire?

NASA Astrophysics Data System (ADS)

Goemaere, Sophie; Beyers, Wim; De Muynck, Gert-Jan; Vansteenkiste, Maarten

2018-06-01

For reasons of bureaucracy and safety, astronauts on the International Space Station are provided with excruciatingly detailed instructions and a lack of decision-making power, even for simple routine tasks. Besides being time-consuming, many astronauts report feelings of demotivation, irritation, and even defiance when confronted with this working method. Anecdotic evidence suggests that this method leads to situations where astronauts read instructions diagonally or avoid checking in with mission support, thereby ironically increasing the risk of error making. There is a need to consider under which circumstances, for whom, and why the provision of long instructions could be detrimental for well-being and performance. An experimental study with LEGO assembly tasks examined whether length of instructions (i.e. short versus long) and task complexity (simple vs. complex) impact negative affect, motivational experiences and performance of participants (N = 113, Mage = 18.75 ± 2.46 years). Long instructions for simple tasks provoked greater feelings of irritation, diminished the perceived value of instructions, and negatively influenced productivity and accuracy. The negative effect of long instructions on irritation was explained via decreased perceived value. Additionally, the effect of length of instructions on irritation differed for participants high versus those low in need for achievement.

Feature extraction with deep neural networks by a generalized discriminant analysis.

PubMed

Stuhlsatz, André; Lippel, Jens; Zielke, Thomas

2012-04-01

We present an approach to feature extraction that is a generalization of the classical linear discriminant analysis (LDA) on the basis of deep neural networks (DNNs). As for LDA, discriminative features generated from independent Gaussian class conditionals are assumed. This modeling has the advantages that the intrinsic dimensionality of the feature space is bounded by the number of classes and that the optimal discriminant function is linear. Unfortunately, linear transformations are insufficient to extract optimal discriminative features from arbitrarily distributed raw measurements. The generalized discriminant analysis (GerDA) proposed in this paper uses nonlinear transformations that are learnt by DNNs in a semisupervised fashion. We show that the feature extraction based on our approach displays excellent performance on real-world recognition and detection tasks, such as handwritten digit recognition and face detection. In a series of experiments, we evaluate GerDA features with respect to dimensionality reduction, visualization, classification, and detection. Moreover, we show that GerDA DNNs can preprocess truly high-dimensional input data to low-dimensional representations that facilitate accurate predictions even if simple linear predictors or measures of similarity are used.

Smart Sensor for Online Detection of Multiple-Combined Faults in VSD-Fed Induction Motors

PubMed Central

Garcia-Ramirez, Armando G.; Osornio-Rios, Roque A.; Granados-Lieberman, David; Garcia-Perez, Arturo; Romero-Troncoso, Rene J.

2012-01-01

Induction motors fed through variable speed drives (VSD) are widely used in different industrial processes. Nowadays, the industry demands the integration of smart sensors to improve the fault detection in order to reduce cost, maintenance and power consumption. Induction motors can develop one or more faults at the same time that can be produce severe damages. The combined fault identification in induction motors is a demanding task, but it has been rarely considered in spite of being a common situation, because it is difficult to identify two or more faults simultaneously. This work presents a smart sensor for online detection of simple and multiple-combined faults in induction motors fed through a VSD in a wide frequency range covering low frequencies from 3 Hz and high frequencies up to 60 Hz based on a primary sensor being a commercially available current clamp or a hall-effect sensor. The proposed smart sensor implements a methodology based on the fast Fourier transform (FFT), RMS calculation and artificial neural networks (ANN), which are processed online using digital hardware signal processing based on field programmable gate array (FPGA).

Developing automated analytical methods for scientific environments using LabVIEW.

PubMed

Wagner, Christoph; Armenta, Sergio; Lendl, Bernhard

2010-01-15

The development of new analytical techniques often requires the building of specially designed devices, each requiring its own dedicated control software. Especially in the research and development phase, LabVIEW has proven to be one highly useful tool for developing this software. Yet, it is still common practice to develop individual solutions for different instruments. In contrast to this, we present here a single LabVIEW-based program that can be directly applied to various analytical tasks without having to change the program code. Driven by a set of simple script commands, it can control a whole range of instruments, from valves and pumps to full-scale spectrometers. Fluid sample (pre-)treatment and separation procedures can thus be flexibly coupled to a wide range of analytical detection methods. Here, the capabilities of the program have been demonstrated by using it for the control of both a sequential injection analysis - capillary electrophoresis (SIA-CE) system with UV detection, and an analytical setup for studying the inhibition of enzymatic reactions using a SIA system with FTIR detection.

Dependency of human target detection performance on clutter and quality of supporting image analysis algorithms in a video surveillance task

NASA Astrophysics Data System (ADS)

Huber, Samuel; Dunau, Patrick; Wellig, Peter; Stein, Karin

2017-10-01

Background: In target detection, the success rates depend strongly on human observer performances. Two prior studies tested the contributions of target detection algorithms and prior training sessions. The aim of this Swiss-German cooperation study was to evaluate the dependency of human observer performance on the quality of supporting image analysis algorithms. Methods: The participants were presented 15 different video sequences. Their task was to detect all targets in the shortest possible time. Each video sequence showed a heavily cluttered simulated public area from a different viewing angle. In each video sequence, the number of avatars in the area was altered to 100, 150 and 200 subjects. The number of targets appearing was kept at 10%. The number of marked targets varied from 0, 5, 10, 20 up to 40 marked subjects while keeping the positive predictive value of the detection algorithm at 20%. During the task, workload level was assessed by applying an acoustic secondary task. Detection rates and detection times for the targets were analyzed using inferential statistics. Results: The study found Target Detection Time to increase and Target Detection Rates to decrease with increasing numbers of avatars. The same is true for the Secondary Task Reaction Time while there was no effect on Secondary Task Hit Rate. Furthermore, we found a trend for a u-shaped correlation between the numbers of markings and RTST indicating increased workload. Conclusion: The trial results may indicate useful criteria for the design of training and support of observers in observational tasks.

Human area MT+ shows load-dependent activation during working memory maintenance with continuously morphing stimulation.

PubMed

Galashan, Daniela; Fehr, Thorsten; Kreiter, Andreas K; Herrmann, Manfred

2014-07-11

Initially, human area MT+ was considered a visual area solely processing motion information but further research has shown that it is also involved in various different cognitive operations, such as working memory tasks requiring motion-related information to be maintained or cognitive tasks with implied or expected motion.In the present fMRI study in humans, we focused on MT+ modulation during working memory maintenance using a dynamic shape-tracking working memory task with no motion-related working memory content. Working memory load was systematically varied using complex and simple stimulus material and parametrically increasing retention periods. Activation patterns for the difference between retention of complex and simple memorized stimuli were examined in order to preclude that the reported effects are caused by differences in retrieval. Conjunction analysis over all delay durations for the maintenance of complex versus simple stimuli demonstrated a wide-spread activation pattern. Percent signal change (PSC) in area MT+ revealed a pattern with higher values for the maintenance of complex shapes compared to the retention of a simple circle and with higher values for increasing delay durations. The present data extend previous knowledge by demonstrating that visual area MT+ presents a brain activity pattern usually found in brain regions that are actively involved in working memory maintenance.

The Developmental Influence of Primary Memory Capacity on Working Memory and Academic Achievement

PubMed Central

2015-01-01

In this study, we investigate the development of primary memory capacity among children. Children between the ages of 5 and 8 completed 3 novel tasks (split span, interleaved lists, and a modified free-recall task) that measured primary memory by estimating the number of items in the focus of attention that could be spontaneously recalled in serial order. These tasks were calibrated against traditional measures of simple and complex span. Clear age-related changes in these primary memory estimates were observed. There were marked individual differences in primary memory capacity, but each novel measure was predictive of simple span performance. Among older children, each measure shared variance with reading and mathematics performance, whereas for younger children, the interleaved lists task was the strongest single predictor of academic ability. We argue that these novel tasks have considerable potential for the measurement of primary memory capacity and provide new, complementary ways of measuring the transient memory processes that predict academic performance. The interleaved lists task also shared features with interference control tasks, and our findings suggest that young children have a particular difficulty in resisting distraction and that variance in the ability to resist distraction is also shared with measures of educational attainment. PMID:26075630

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.

The developmental influence of primary memory capacity on working memory and academic achievement.

PubMed

Hall, Debbora; Jarrold, Christopher; Towse, John N; Zarandi, Amy L

2015-08-01

In this study, we investigate the development of primary memory capacity among children. Children between the ages of 5 and 8 completed 3 novel tasks (split span, interleaved lists, and a modified free-recall task) that measured primary memory by estimating the number of items in the focus of attention that could be spontaneously recalled in serial order. These tasks were calibrated against traditional measures of simple and complex span. Clear age-related changes in these primary memory estimates were observed. There were marked individual differences in primary memory capacity, but each novel measure was predictive of simple span performance. Among older children, each measure shared variance with reading and mathematics performance, whereas for younger children, the interleaved lists task was the strongest single predictor of academic ability. We argue that these novel tasks have considerable potential for the measurement of primary memory capacity and provide new, complementary ways of measuring the transient memory processes that predict academic performance. The interleaved lists task also shared features with interference control tasks, and our findings suggest that young children have a particular difficulty in resisting distraction and that variance in the ability to resist distraction is also shared with measures of educational attainment. (c) 2015 APA, all rights reserved).

A Long-Term BCI Study With ECoG Recordings in Freely Moving Rats.

PubMed

Costecalde, Thomas; Aksenova, Tetiana; Torres-Martinez, Napoleon; Eliseyev, Andriy; Mestais, Corinne; Moro, Cecile; Benabid, Alim Louis

2018-02-01

Brain Computer Interface (BCI) studies are performed in an increasing number of applications. Questions are raised about electrodes, data processing and effectors. Experiments are needed to solve these issues. To develop a simple BCI set-up to easier studies for improving the mathematical tools to process the ECoG to control an effector. We designed a simple BCI using transcranial electrodes (17 screws, three mechanically linked to create a common reference, 14 used as recording electrodes) to record Electro-Cortico-Graphic (ECoG) neuronal activities in rodents. The data processing is based on an online self-paced non-supervised (asynchronous) BCI paradigm. N-way partial least squares algorithm together with Continuous Wavelet Transformation of ECoG recordings detect signatures related to motor activities. Signature detection in freely moving rats may activate external effectors during a behavioral task, which involved pushing a lever to obtain a reward. After routine training, we showed that peak brain activity preceding a lever push (LP) to obtain food reward was located mostly in the cerebellar cortex with a higher correlation coefficient, suggesting a strong postural component and also in the occipital cerebral cortex. Analysis of brain activities provided a stable signature in the high gamma band (∼180Hz) occurring within 1500 msec before the lever push approximately around -400 msec to -500 msec. Detection of the signature from a single cerebellar cortical electrode triggers the effector with high efficiency (68% Offline and 30% Online) and rare false positives per minute in sessions about 30 minutes and up to one hour (∼2 online and offline). In summary, our results are original as compared to the rest of the literature, which involves rarely rodents, a simple BCI set-up has been developed in rats, the data show for the first time long-term, up to one year, unsupervised online control of an effector. © 2017 International Neuromodulation Society.

Is Sensitivity to Rhyme a Developmental Precursor to Sensitivity to Phoneme?: Evidence from Individuals with Down Syndrome.

ERIC Educational Resources Information Center

Cardoso-Martins, Claudia; Michalick, Mirelle Franca; Pollo, Tatiana Cury

2002-01-01

Investigates sensitivity to rhyme and phoneme among readers and nonreaders with Down Syndrome (DS) and normally developing children. Evaluates a rhyme detection task and initial and middle phoneme detection tasks. Concludes the rhyme detection task was the easiest for nonreaders without DS and most difficult for readers with DS. (PM)

Suicidality assessment with PRISM-S - simple, fast, and visual: a brief nonverbal method to assess suicidality in adolescent and adult patients.

PubMed

Harbauer, Gregor; Ring, Mariann; Schuetz, Christopher; Andreae, Andreas; Haas, Sebastian

2013-01-01

The PRISM-S task was developed at the Crisis Intervention Center (KIZ) Winterthur, Switzerland, to enable an assessment of the degree of suicidality in less than 5 minutes with a simple, visual instrument. Comparison of validity and clinical use of the new PRISM-S task with other instruments known as "gold standards". Quantitative pilot study enlisting 100 inpatients admitted to the KIZ, aged 15-42 years. Patients' suicidality was assessed by the PRISM-S task during the first clinical interview and compared to data obtained by standardized suicidality instruments. The patients completed the PRISM-S task in 2 to 5 minutes without difficulty. Data show significant positive correlations between the suicidality as assessed by PRISM-S and the gold standards, i.e., DSI-SS (r = 0.59, N = 65, p < .0001). There is no strong evidence that PRISM-S is useful for outpatients or in other settings. The experiences gained with outpatients/patients with other disorders are promising but have not been systematically evaluated. The results do not rely on a randomized design. The sample consists of persons coming to the crisis intervention center. PRISM-S offers a brief, easy-to-administer, and valid method to assess patients' suicidality. The simple instruction facilitates its use in other languages and other cultures as well. The acceptance by patients and health professionals was good, with no one refusing to complete the task.

An efficient temporal logic for robotic task planning

NASA Technical Reports Server (NTRS)

Becker, Jeffrey M.

1989-01-01

Computations required for temporal reasoning can be prohibitively expensive if fully general representations are used. Overly simple representations, such as totally ordered sequence of time points, are inadequate for use in a nonlinear task planning system. A middle ground is identified which is general enough to support a capable nonlinear task planner, but specialized enough that the system can support online task planning in real time. A Temporal Logic System (TLS) was developed during the Intelligent Task Automation (ITA) project to support robotic task planning. TLS is also used within the ITA system to support plan execution, monitoring, and exception handling.

Implied functional crossed cerebello-cerebral diaschisis and interhemispheric compensation during hand grasping more than 20 years after unilateral cerebellar injury in early childhood.

PubMed

Nakahachi, Takayuki; Ishii, Ryouhei; Canuet, Leonides; Iwase, Masao

2015-01-01

Crossed cerebello-cerebral diaschisis (CCCD) conventionally refers to decreased resting cerebral activity caused by injury to the contralateral cerebellum. We investigated whether functional activation of a contralesional cerebral cortical region controlling a specific task is reduced during task performance in a patient with a unilateral cerebellar lesion. We also examined functional compensation by the corresponding ipsilesional cerebral cortex. It was hypothesized that dysfunction of the primary sensorimotor cortex (SM1) contralateral to the cerebellar lesion would be detected together with a compensatory increase in neural activity of the ipsilesional SM1. To test these possibilities, we conducted non-invasive functional neuroimaging techniques for bilateral SM1 during hand grasping, a task known to activate predominantly the SM1 contralateral to the grasping hand. Activity in SM1 during hand grasping was measured electrophysiologically by magnetoencephalography and hemodynamically by near-infrared spectroscopy in an adult with mild right hemiataxia associated with a large injury of the right cerebellum due to resection of a tumor in early childhood. During left hand grasping, increased neural activity was detected predominantly in the right SM1, the typical developmental pattern. In contrast, neural activity increased in the bilateral SM1 with slight right-side dominance during right (ataxic) hand grasping. This study reported a case that implied functional CCCD and compensatory neural activity in the SM1 during performance of a simple hand motor task in an adult with unilateral cerebellar injury and mild hemiataxia 24 years prior to the study without rehabilitative interventions. This suggests that unilateral cerebellar injuries in early childhood may result in persistent functional abnormalities in the cerebrum into adulthood. Therapeutic treatments that target functional CCCD and interhemispheric compensation might be effective for treating ataxia due to unilateral cerebellar damage.

Costs of storing colour and complex shape in visual working memory: Insights from pupil size and slow waves.

PubMed

Kursawe, Michael A; Zimmer, Hubert D

2015-06-01

We investigated the impact of perceptual processing demands on visual working memory of coloured complex random polygons during change detection. Processing load was assessed by pupil size (Exp. 1) and additionally slow wave potentials (Exp. 2). Task difficulty was manipulated by presenting different set sizes (1, 2, 4 items) and by making different features (colour, shape, or both) task-relevant. Memory performance in the colour condition was better than in the shape and both condition which did not differ. Pupil dilation and the posterior N1 increased with set size independent of type of feature. In contrast, slow waves and a posterior P2 component showed set size effects but only if shape was task-relevant. In the colour condition slow waves did not vary with set size. We suggest that pupil size and N1 indicates different states of attentional effort corresponding to the number of presented items. In contrast, slow waves reflect processes related to encoding and maintenance strategies. The observation that their potentials vary with the type of feature (simple colour versus complex shape) indicates that perceptual complexity already influences encoding and storage and not only comparison of targets with memory entries at the moment of testing. Copyright © 2015 Elsevier B.V. All rights reserved.

Guiding the study of brain dynamics by using first-person data: Synchrony patterns correlate with ongoing conscious states during a simple visual task

PubMed Central

Lutz, Antoine; Lachaux, Jean-Philippe; Martinerie, Jacques; Varela, Francisco J.

2002-01-01

Even during well-calibrated cognitive tasks, successive brain responses to repeated identical stimulations are highly variable. The source of this variability is believed to reside mainly in fluctuations of the subject's cognitive “context” defined by his/her attentive state, spontaneous thought process, strategy to carry out the task, and so on … As these factors are hard to manipulate precisely, they are usually not controlled, and the variability is discarded by averaging techniques. We combined first-person data and the analysis of neural processes to reduce such noise. We presented the subjects with a three-dimensional illusion and recorded their electrical brain activity and their own report about their cognitive context. Trials were clustered according to these first-person data, and separate dynamical analyses were conducted for each cluster. We found that (i) characteristic patterns of endogenous synchrony appeared in frontal electrodes before stimulation. These patterns depended on the degree of preparation and the immediacy of perception as verbally reported. (ii) These patterns were stable for several recordings. (iii) Preparatory states modulate both the behavioral performance and the evoked and induced synchronous patterns that follow. (iv) These results indicated that first-person data can be used to detect and interpret neural processes. PMID:11805299

Age Differences in Visual-Auditory Self-Motion Perception during a Simulated Driving Task

PubMed Central

Ramkhalawansingh, Robert; Keshavarz, Behrang; Haycock, Bruce; Shahab, Saba; Campos, Jennifer L.

2016-01-01

Recent evidence suggests that visual-auditory cue integration may change as a function of age such that integration is heightened among older adults. Our goal was to determine whether these changes in multisensory integration are also observed in the context of self-motion perception under realistic task constraints. Thus, we developed a simulated driving paradigm in which we provided older and younger adults with visual motion cues (i.e., optic flow) and systematically manipulated the presence or absence of congruent auditory cues to self-motion (i.e., engine, tire, and wind sounds). Results demonstrated that the presence or absence of congruent auditory input had different effects on older and younger adults. Both age groups demonstrated a reduction in speed variability when auditory cues were present compared to when they were absent, but older adults demonstrated a proportionally greater reduction in speed variability under combined sensory conditions. These results are consistent with evidence indicating that multisensory integration is heightened in older adults. Importantly, this study is the first to provide evidence to suggest that age differences in multisensory integration may generalize from simple stimulus detection tasks to the integration of the more complex and dynamic visual and auditory cues that are experienced during self-motion. PMID:27199829

Nonparametric EROC analysis for observer performance evaluation on joint detection and estimation tasks

NASA Astrophysics Data System (ADS)

Wunderlich, Adam; Goossens, Bart

2014-03-01

The majority of the literature on task-based image quality assessment has focused on lesion detection tasks, using the receiver operating characteristic (ROC) curve, or related variants, to measure performance. However, since many clinical image evaluation tasks involve both detection and estimation (e.g., estimation of kidney stone composition, estimation of tumor size), there is a growing interest in performance evaluation for joint detection and estimation tasks. To evaluate observer performance on such tasks, Clarkson introduced the estimation ROC (EROC) curve, and the area under the EROC curve as a summary figure of merit. In the present work, we propose nonparametric estimators for practical EROC analysis from experimental data, including estimators for the area under the EROC curve and its variance. The estimators are illustrated with a practical example comparing MRI images reconstructed from different k-space sampling trajectories.

The performance of ravens on simple discrimination tasks: a preliminary study

PubMed Central

Range, Friederike; Bugnyar, Thomas; Kotrschal, Kurt

2015-01-01

Recent studies suggest the existence of primate-like cognitive abilities in corvids. Although the learning abilities of corvids in comparison to other species have been investigated before, little is known on how corvids perform on simple discrimination tasks if tested in experimental settings comparable to those that have been used for studying complex cognitive abilities. In this study, we tested a captive group of 12 ravens (Corvus corax) on four discrimination problems and their reversals. In contrast to other studies investigating learning abilities, our ravens were not food deprived and participation in experiments was voluntary. This preliminary study showed that all ravens successfully solved feature and position discriminations and several of the ravens could solve new tasks in a few trials, making very few mistakes. PMID:25948877

Signal detection theory applied to three visual search tasks--identification, yes/no detection and localization.

PubMed

Cameron, E Leslie; Tai, Joanna C; Eckstein, Miguel P; Carrasco, Marisa

2004-01-01

Adding distracters to a display impairs performance on visual tasks (i.e. the set-size effect). While keeping the display characteristics constant, we investigated this effect in three tasks: 2 target identification, yes-no detection with 2 targets, and 8-alternative localization. A Signal Detection Theory (SDT) model, tailored for each task, accounts for the set-size effects observed in identification and localization tasks, and slightly under-predicts the set-size effect in a detection task. Given that sensitivity varies as a function of spatial frequency (SF), we measured performance in each of these three tasks in neutral and peripheral precue conditions for each of six spatial frequencies (0.5-12 cpd). For all spatial frequencies tested, performance on the three tasks decreased as set size increased in the neutral precue condition, and the peripheral precue reduced the effect. Larger set-size effects were observed at low SFs in the identification and localization tasks. This effect can be described using the SDT model, but was not predicted by it. For each of these tasks we also established the extent to which covert attention modulates performance across a range of set sizes. A peripheral precue substantially diminished the set-size effect and improved performance, even at set size 1. These results provide support for distracter exclusion, and suggest that signal enhancement may also be a mechanism by which covert attention can impose its effect.

Simplest chronoscope. III. Further comparisons between reaction times obtained by meterstick versus machine.

PubMed

Montare, Alberto

2013-06-01

The three classical Donders' reaction time (RT) tasks (simple, choice, and discriminative RTs) were employed to compare reaction time scores from college students obtained by use of Montare's simplest chronoscope (meterstick) methodology to scores obtained by use of a digital-readout multi-choice reaction timer (machine). Five hypotheses were tested. Simple RT, choice RT, and discriminative RT were faster when obtained by meterstick than by machine. The meterstick method showed higher reliability than the machine method and was less variable. The meterstick method of the simplest chronoscope may help to alleviate the longstanding problems of low reliability and high variability of reaction time performances; while at the same time producing faster performance on Donders' simple, choice and discriminative RT tasks than the machine method.

Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity.

PubMed

Ambrose, Joseph P; Wijeakumar, Sobanawartiny; Buss, Aaron T; Spencer, John P

2016-01-01

Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3-4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work.

Automated design of image operators that detect interest points.

PubMed

Trujillo, Leonardo; Olague, Gustavo

2008-01-01

This work describes how evolutionary computation can be used to synthesize low-level image operators that detect interesting points on digital images. Interest point detection is an essential part of many modern computer vision systems that solve tasks such as object recognition, stereo correspondence, and image indexing, to name but a few. The design of the specialized operators is posed as an optimization/search problem that is solved with genetic programming (GP), a strategy still mostly unexplored by the computer vision community. The proposed approach automatically synthesizes operators that are competitive with state-of-the-art designs, taking into account an operator's geometric stability and the global separability of detected points during fitness evaluation. The GP search space is defined using simple primitive operations that are commonly found in point detectors proposed by the vision community. The experiments described in this paper extend previous results (Trujillo and Olague, 2006a,b) by presenting 15 new operators that were synthesized through the GP-based search. Some of the synthesized operators can be regarded as improved manmade designs because they employ well-known image processing techniques and achieve highly competitive performance. On the other hand, since the GP search also generates what can be considered as unconventional operators for point detection, these results provide a new perspective to feature extraction research.

Psychophysical Models for Signal Detection with Time Varying Uncertainty. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Gai, E.

1975-01-01

Psychophysical models for the behavior of the human operator in detection tasks which include change in detectability, correlation between observations and deferred decisions are developed. Classical Signal Detection Theory (SDT) is discussed and its emphasis on the sensory processes is contrasted to decision strategies. The analysis of decision strategies utilizes detection tasks with time varying signal strength. The classical theory is modified to include such tasks and several optimal decision strategies are explored. Two methods of classifying strategies are suggested. The first method is similar to the analysis of ROC curves, while the second is based on the relation between the criterion level (CL) and the detectability. Experiments to verify the analysis of tasks with changes of signal strength are designed. The results show that subjects are aware of changes in detectability and tend to use strategies that involve changes in the CL's.

A Not-So-Simple View of Adolescent Writing

ERIC Educational Resources Information Center

Poch, Apryl L.; Lembke, Erica S.

2017-01-01

According to the Simple View of Writing, four primary skills are necessary for successful writing (Berninger & Amtmann, 2003; Berninger & Winn, 2006). Transcription skills (e.g., handwriting, spelling) represent lower-order cognitive tasks, whereas text generation skills (e.g., ideation, translation) represent higher-order…

Music and Sound in Time Processing of Children with ADHD

PubMed Central

Carrer, Luiz Rogério Jorgensen

2015-01-01

ADHD involves cognitive and behavioral aspects with impairments in many environments of children and their families’ lives. Music, with its playful, spontaneous, affective, motivational, temporal, and rhythmic dimensions can be of great help for studying the aspects of time processing in ADHD. In this article, we studied time processing with simple sounds and music in children with ADHD with the hypothesis that children with ADHD have a different performance when compared with children with normal development in tasks of time estimation and production. The main objective was to develop sound and musical tasks to evaluate and correlate the performance of children with ADHD, with and without methylphenidate, compared to a control group with typical development. The study involved 36 participants of age 6–14 years, recruited at NANI-UNIFESP/SP, subdivided into three groups with 12 children in each. Data was collected through a musical keyboard using Logic Audio Software 9.0 on the computer that recorded the participant’s performance in the tasks. Tasks were divided into sections: spontaneous time production, time estimation with simple sounds, and time estimation with music. Results: (1) performance of ADHD groups in temporal estimation of simple sounds in short time intervals (30 ms) were statistically lower than that of control group (p < 0.05); (2) in the task comparing musical excerpts of the same duration (7 s), ADHD groups considered the tracks longer when the musical notes had longer durations, while in the control group, the duration was related to the density of musical notes in the track. The positive average performance observed in the three groups in most tasks perhaps indicates the possibility that music can, in some way, positively modulate the symptoms of inattention in ADHD. PMID:26441688

Arthroscopic skills assessment and use of box model for training in arthroscopic surgery using Sawbones – “FAST” workstation

PubMed Central

Goyal, Saumitra; Radi, Mohamed Abdel; Ramadan, Islam Karam-allah; Said, Hatem Galal

2016-01-01

Purpose: Arthroscopic skills training outside the operative room may decrease risks and errors by trainee surgeons. There is a need of simple objective method for evaluating proficiency and skill of arthroscopy trainees using simple bench model of arthroscopic simulator. The aim of this study is to correlate motor task performance to level of prior arthroscopic experience and establish benchmarks for training modules. Methods: Twenty orthopaedic surgeons performed a set of tasks to assess a) arthroscopic triangulation, b) navigation, c) object handling and d) meniscus trimming using SAWBONES “FAST” arthroscopy skills workstation. Time to completion and the errors were computed. The subjects were divided into four levels; “Novice”, “Beginner”, “Intermediate” and “Advanced” based on previous arthroscopy experience, for analyses of performance. Results: The task performance under transparent dome was not related to experience of the surgeon unlike opaque dome, highlighting the importance of hand-eye co-ordination required in arthroscopy. Median time to completion for each task improved as the level of experience increased and this was found to be statistically significant (p < .05) e.g. time for maze navigation (Novice – 166 s, Beginner – 135.5 s, Intermediate – 100 s, Advance – 97.5 s) and the similar results for all tasks. Majority (>85%) of subjects across all the levels reported improvement in performance with sequential tasks. Conclusion: Use of the arthroscope requires visuo-spatial coordination which is a skill that develops with practice. This simple box model can reliably differentiate the arthroscopic skills based on experience and can be used to monitor progression of skills of trainees in institutions. PMID:27801643

Music and Sound in Time Processing of Children with ADHD.

PubMed

Carrer, Luiz Rogério Jorgensen

2015-01-01

ADHD involves cognitive and behavioral aspects with impairments in many environments of children and their families' lives. Music, with its playful, spontaneous, affective, motivational, temporal, and rhythmic dimensions can be of great help for studying the aspects of time processing in ADHD. In this article, we studied time processing with simple sounds and music in children with ADHD with the hypothesis that children with ADHD have a different performance when compared with children with normal development in tasks of time estimation and production. The main objective was to develop sound and musical tasks to evaluate and correlate the performance of children with ADHD, with and without methylphenidate, compared to a control group with typical development. The study involved 36 participants of age 6-14 years, recruited at NANI-UNIFESP/SP, subdivided into three groups with 12 children in each. Data was collected through a musical keyboard using Logic Audio Software 9.0 on the computer that recorded the participant's performance in the tasks. Tasks were divided into sections: spontaneous time production, time estimation with simple sounds, and time estimation with music. (1) performance of ADHD groups in temporal estimation of simple sounds in short time intervals (30 ms) were statistically lower than that of control group (p < 0.05); (2) in the task comparing musical excerpts of the same duration (7 s), ADHD groups considered the tracks longer when the musical notes had longer durations, while in the control group, the duration was related to the density of musical notes in the track. The positive average performance observed in the three groups in most tasks perhaps indicates the possibility that music can, in some way, positively modulate the symptoms of inattention in ADHD.

The Watchdog Task: Concurrent error detection using assertions

NASA Technical Reports Server (NTRS)

Ersoz, A.; Andrews, D. M.; Mccluskey, E. J.

1985-01-01

The Watchdog Task, a software abstraction of the Watchdog-processor, is shown to be a powerful error detection tool with a great deal of flexibility and the advantages of watchdog techniques. A Watchdog Task system in Ada is presented; issues of recovery, latency, efficiency (communication) and preprocessing are discussed. Different applications, one of which is error detection on a single processor, are examined.

CQPSO scheduling algorithm for heterogeneous multi-core DAG task model

NASA Astrophysics Data System (ADS)

Zhai, Wenzheng; Hu, Yue-Li; Ran, Feng

2017-07-01

Efficient task scheduling is critical to achieve high performance in a heterogeneous multi-core computing environment. The paper focuses on the heterogeneous multi-core directed acyclic graph (DAG) task model and proposes a novel task scheduling method based on an improved chaotic quantum-behaved particle swarm optimization (CQPSO) algorithm. A task priority scheduling list was built. A processor with minimum cumulative earliest finish time (EFT) was acted as the object of the first task assignment. The task precedence relationships were satisfied and the total execution time of all tasks was minimized. The experimental results show that the proposed algorithm has the advantage of optimization abilities, simple and feasible, fast convergence, and can be applied to the task scheduling optimization for other heterogeneous and distributed environment.

Reconciling change blindness with long-term memory for objects.

PubMed

Wood, Katherine; Simons, Daniel J

2017-02-01

How can we reconcile remarkably precise long-term memory for thousands of images with failures to detect changes to similar images? We explored whether people can use detailed, long-term memory to improve change detection performance. Subjects studied a set of images of objects and then performed recognition and change detection tasks with those images. Recognition memory performance exceeded change detection performance, even when a single familiar object in the postchange display consistently indicated the change location. In fact, participants were no better when a familiar object predicted the change location than when the displays consisted of unfamiliar objects. When given an explicit strategy to search for a familiar object as a way to improve performance on the change detection task, they performed no better than in a 6-alternative recognition memory task. Subjects only benefited from the presence of familiar objects in the change detection task when they had more time to view the prechange array before it switched. Once the cost to using the change detection information decreased, subjects made use of it in conjunction with memory to boost performance on the familiar-item change detection task. This suggests that even useful information will go unused if it is sufficiently difficult to extract.

Hippocampus duality: Memory and novelty detection are subserved by distinct mechanisms.

PubMed

Barbeau, Emmanuel J; Chauvel, Patrick; Moulin, Christopher J A; Regis, Jean; Liégeois-Chauvel, Catherine

2017-04-01

The hippocampus plays a pivotal role both in novelty detection and in long-term memory. The physiological mechanisms underlying these behaviors have yet to be understood in humans. We recorded intracerebral evoked potentials within the hippocampus of epileptic patients (n = 10) during both memory and novelty detection tasks (targets in oddball tasks). We found that memory and detection tasks elicited late local field potentials in the hippocampus during the same period, but of opposite polarity (negative during novelty detection tasks, positive during memory tasks, ∼260-600 ms poststimulus onset, P < 0.05). Critically, these potentials had maximal amplitude on the same contact in the hippocampus for each patient. This pattern did not depend on the task as different types of memory and novelty detection tasks were used. It did not depend on the novelty of the stimulus or the difficulty of the task either. Two different hypotheses are discussed to account for this result: it is either due to the activation of CA1 pyramidal neurons by two different pathways such as the monosynaptic and trisynaptic entorhinal-hippocampus pathways, or to the activation of different neuronal populations, that is, differing either functionally (e.g., novelty/familiarity neurons) or located in different regions of the hippocampus (e.g., CA1/subiculum). In either case, these activities may integrate the activity of two distinct large-scale networks implementing externally or internally oriented, mutually exclusive, brain states. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Speed of Processing and Reading Disability: A Cross-Linguistic Investigation of Dyslexia and Borderline Intellectual Functioning

ERIC Educational Resources Information Center

Bonifacci, Paola; Snowling, Margaret J.

2008-01-01

English and Italian children with dyslexia were compared with children with reading difficulties associated with low-IQ on tests of simple and choice RT, and in number and symbol scanning tasks. On all four speed-of-processing tasks, children with low-IQ responded more slowly than children with dyslexia and age-controls. In the choice RT task, the…

Bottom-Up Mechanisms Are Involved in the Relation between Accuracy in Timing Tasks and Intelligence--Further Evidence Using Manipulations of State Motivation

ERIC Educational Resources Information Center

Ullen, Fredrik; Soderlund, Therese; Kaaria, Lenita; Madison, Guy

2012-01-01

Intelligence correlates with accuracy in various timing tasks. Such correlations could be due to both bottom-up mechanisms, e.g. neural properties that influence both temporal accuracy and cognitive processing, and differences in top-down control. We have investigated the timing-intelligence relation using a simple temporal motor task, isochronous…

The Effect of Job Performance Aids on Quality Assurance

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

Fosshage, Erik

Job performance aids (JPAs) have been studied for many decades in a variety of disciplines and for many different types of tasks, yet this is the first known research experiment using JPAs in a quality assurance (QA) context. The objective of this thesis was to assess whether a JPA has an effect on the performance of a QA observer performing the concurrent dual verification technique for a basic assembly task. The JPA used in this study was a simple checklist, and the design borrows heavily from prior research on task analysis and other human factors principles. The assembly task andmore » QA construct of concurrent dual verification are consistent with those of a high consequence manufacturing environment. Results showed that the JPA had only a limited effect on QA performance in the context of this experiment. However, there were three important and unexpected findings that may draw interest from a variety of practitioners. First, a novel testing methodology sensitive enough to measure the effects of a JPA on performance was created. Second, the discovery that there are different probabilities of detection for different types of error in a QA context may be the most far-reaching results. Third, these results highlight the limitations of concurrent dual verification as a control against defects. It is hoped that both the methodology and results of this study are an effective baseline from which to launch future research activities.« less

Sustained attention ability in schizophrenia: Investigation of conflict monitoring mechanisms.

PubMed

Hoonakker, Marc; Doignon-Camus, Nadège; Marques-Carneiro, José Eduardo; Bonnefond, Anne

2017-09-01

The main goal of the current study was to assess, with a time-on-task approach, sustained attention ability in schizophrenia, and to investigate conflict monitoring underlying this ability. Behavioral and event-related potentials data (N2 and P3a amplitudes) were recorded in a long-lasting sustained attention Go/NoGo task (sustained attention to response task, SART), over a period of 30min, in 29 patients with schizophrenia and 29 pair-matched healthy subjects. Our results revealed spared sustained attention ability in patients throughout the task. Impairment of conflict detection (N2) in patients was particularly significant at the end of the task. Furthermore, both schizophrenia and healthy subjects exhibited a decline in conflict detection from the beginning to the middle of the task. Whereas controls' conflict detection recovered in the last part of the task, patients' did not, suggesting a deficit in recovery processes reflecting a lack of additional resources sustained attention Go/NoGo task. Conflict resolution (P3a) was preserved throughout the task in both groups. Conflict monitoring processes are increasingly impaired in schizophrenia during a long-lasting sustained attention Go/NoGo task. This impairment at the end of the task may rely on deficit in recovery processes, rather than a deficit in conflict detection per se in schizophrenia. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Perceptual Visual Grouping under Inattention: Electrophysiological Functional Imaging

ERIC Educational Resources Information Center

Razpurker-Apfeld, Irene; Pratt, Hillel

2008-01-01

Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were…

Syntactic Recursion Facilitates and Working Memory Predicts Recursive Theory of Mind

PubMed Central

Arslan, Burcu; Hohenberger, Annette; Verbrugge, Rineke

2017-01-01

In this study, we focus on the possible roles of second-order syntactic recursion and working memory in terms of simple and complex span tasks in the development of second-order false belief reasoning. We tested 89 Turkish children in two age groups, one younger (4;6–6;5 years) and one older (6;7–8;10 years). Although second-order syntactic recursion is significantly correlated with the second-order false belief task, results of ordinal logistic regressions revealed that the main predictor of second-order false belief reasoning is complex working memory span. Unlike simple working memory and second-order syntactic recursion tasks, the complex working memory task required processing information serially with additional reasoning demands that require complex working memory strategies. Based on our results, we propose that children’s second-order theory of mind develops when they have efficient reasoning rules to process embedded beliefs serially, thus overcoming a possible serial processing bottleneck. PMID:28072823

Choosing Actions

PubMed Central

Rosenbaum, David A.; Chapman, Kate M.; Coelho, Chase J.; Gong, Lanyun; Studenka, Breanna E.

2013-01-01

Actions that are chosen have properties that distinguish them from actions that are not. Of the nearly infinite possible actions that can achieve any given task, many of the unchosen actions are irrelevant, incorrect, or inappropriate. Others are relevant, correct, or appropriate but are disfavored for other reasons. Our research focuses on the question of what distinguishes actions that are chosen from actions that are possible but are not. We review studies that use simple preference methods to identify factors that contribute to action choices, especially for object-manipulation tasks. We can determine which factors are especially important through simple behavioral experiments. PMID:23761769

Task-driven imaging in cone-beam computed tomography.

PubMed

Gang, G J; Stayman, J W; Ouadah, S; Ehtiati, T; Siewerdsen, J H

Conventional workflow in interventional imaging often ignores a wealth of prior information of the patient anatomy and the imaging task. This work introduces a task-driven imaging framework that utilizes such information to prospectively design acquisition and reconstruction techniques for cone-beam CT (CBCT) in a manner that maximizes task-based performance in subsequent imaging procedures. The framework is employed in jointly optimizing tube current modulation, orbital tilt, and reconstruction parameters in filtered backprojection reconstruction for interventional imaging. Theoretical predictors of noise and resolution relates acquisition and reconstruction parameters to task-based detectability. Given a patient-specific prior image and specification of the imaging task, an optimization algorithm prospectively identifies the combination of imaging parameters that maximizes task-based detectability. Initial investigations were performed for a variety of imaging tasks in an elliptical phantom and an anthropomorphic head phantom. Optimization of tube current modulation and view-dependent reconstruction kernel was shown to have greatest benefits for a directional task (e.g., identification of device or tissue orientation). The task-driven approach yielded techniques in which the dose and sharp kernels were concentrated in views contributing the most to the signal power associated with the imaging task. For example, detectability of a line pair detection task was improved by at least three fold compared to conventional approaches. For radially symmetric tasks, the task-driven strategy yielded results similar to a minimum variance strategy in the absence of kernel modulation. Optimization of the orbital tilt successfully avoided highly attenuating structures that can confound the imaging task by introducing noise correlations masquerading at spatial frequencies of interest. This work demonstrated the potential of a task-driven imaging framework to improve image quality and reduce dose beyond that achievable with conventional imaging approaches.

Evaluation of selected auditory tests in school-age children suspected of auditory processing disorders.

PubMed

Vanniasegaram, Iyngaram; Cohen, Mazal; Rosen, Stuart

2004-12-01

To compare the auditory function of normal-hearing children attending mainstream schools who were referred for an auditory evaluation because of listening/hearing problems (suspected auditory processing disorders [susAPD]) with that of normal-hearing control children. Sixty-five children with a normal standard audiometric evaluation, ages 6-14 yr (32 of whom were referred for susAPD, with the rest age-matched control children), completed a battery of four auditory tests: a dichotic test of competing sentences; a simple discrimination of short tone pairs differing in fundamental frequency at varying interstimulus intervals (TDT); a discrimination task using consonant cluster minimal pairs of real words (CCMP), and an adaptive threshold task for detecting a brief tone presented either simultaneously with a masker (simultaneous masking) or immediately preceding it (backward masking). Regression analyses, including age as a covariate, were performed to determine the extent to which the performance of the two groups differed on each task. Age-corrected z-scores were calculated to evaluate the effectiveness of the complete battery in discriminating the groups. The performance of the susAPD group was significantly poorer than the control group on all but the masking tasks, which failed to differentiate the two groups. The CCMP discriminated the groups most effectively, as it yielded the lowest number of control children with abnormal scores, and performance in both groups was independent of age. By contrast, the proportion of control children who performed poorly on the competing sentences test was unacceptably high. Together, the CCMP (verbal) and TDT (nonverbal) tasks detected impaired listening skills in 56% of the children who were referred to the clinic, compared with 6% of the control children. Performance on the two tasks was not correlated. Two of the four tests evaluated, the CCMP and TDT, proved effective in differentiating the two groups of children of this study. The application of both tests increased the proportion of susAPD children who performed poorly compared with the application of each test alone, while reducing the proportion of control subjects who performed poorly. The findings highlight the importance of carrying out a complete auditory evaluation in children referred for medical attention, even if their standard audiometric evaluation is unremarkable.

A Brief Period of Postnatal Visual Deprivation Alters the Balance between Auditory and Visual Attention.

PubMed

de Heering, Adélaïde; Dormal, Giulia; Pelland, Maxime; Lewis, Terri; Maurer, Daphne; Collignon, Olivier

2016-11-21

Is a short and transient period of visual deprivation early in life sufficient to induce lifelong changes in how we attend to, and integrate, simple visual and auditory information [1, 2]? This question is of crucial importance given the recent demonstration in both animals and humans that a period of blindness early in life permanently affects the brain networks dedicated to visual, auditory, and multisensory processing [1-16]. To address this issue, we compared a group of adults who had been treated for congenital bilateral cataracts during early infancy with a group of normally sighted controls on a task requiring simple detection of lateralized visual and auditory targets, presented alone or in combination. Redundancy gains obtained from the audiovisual conditions were similar between groups and surpassed the reaction time distribution predicted by Miller's race model. However, in comparison to controls, cataract-reversal patients were faster at processing simple auditory targets and showed differences in how they shifted attention across modalities. Specifically, they were faster at switching attention from visual to auditory inputs than in the reverse situation, while an opposite pattern was observed for controls. Overall, these results reveal that the absence of visual input during the first months of life does not prevent the development of audiovisual integration but enhances the salience of simple auditory inputs, leading to a different crossmodal distribution of attentional resources between auditory and visual stimuli. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification of Swallowing Tasks from a Modified Barium Swallow Study That Optimize the Detection of Physiological Impairment

ERIC Educational Resources Information Center

Hazelwood, R. Jordan; Armeson, Kent E.; Hill, Elizabeth G.; Bonilha, Heather Shaw; Martin-Harris, Bonnie

2017-01-01

Purpose: The purpose of this study was to identify which swallowing task(s) yielded the worst performance during a standardized modified barium swallow study (MBSS) in order to optimize the detection of swallowing impairment. Method: This secondary data analysis of adult MBSSs estimated the probability of each swallowing task yielding the derived…

Enhanced attention amplifies face adaptation.

PubMed

Rhodes, Gillian; Jeffery, Linda; Evangelista, Emma; Ewing, Louise; Peters, Marianne; Taylor, Libby

2011-08-15

Perceptual adaptation not only produces striking perceptual aftereffects, but also enhances coding efficiency and discrimination by calibrating coding mechanisms to prevailing inputs. Attention to simple stimuli increases adaptation, potentially enhancing its functional benefits. Here we show that attention also increases adaptation to faces. In Experiment 1, face identity aftereffects increased when attention to adapting faces was increased using a change detection task. In Experiment 2, figural (distortion) face aftereffects increased when attention was increased using a snap game (detecting immediate repeats) during adaptation. Both were large effects. Contributions of low-level adaptation were reduced using free viewing (both experiments) and a size change between adapt and test faces (Experiment 2). We suggest that attention may enhance adaptation throughout the entire cortical visual pathway, with functional benefits well beyond the immediate advantages of selective processing of potentially important stimuli. These results highlight the potential to facilitate adaptive updating of face-coding mechanisms by strategic deployment of attentional resources. Copyright © 2011 Elsevier Ltd. All rights reserved.

Control and near-field detection of surface plasmon interference patterns.

PubMed

Dvořák, Petr; Neuman, Tomáš; Břínek, Lukáš; Šamořil, Tomáš; Kalousek, Radek; Dub, Petr; Varga, Peter; Šikola, Tomáš

2013-06-12

The tailoring of electromagnetic near-field properties is the central task in the field of nanophotonics. In addition to 2D optics for optical nanocircuits, confined and enhanced electric fields are utilized in detection and sensing, photovoltaics, spatially localized spectroscopy (nanoimaging), as well as in nanolithography and nanomanipulation. For practical purposes, it is necessary to develop easy-to-use methods for controlling the electromagnetic near-field distribution. By imaging optical near-fields using a scanning near-field optical microscope, we demonstrate that surface plasmon polaritons propagating from slits along the metal-dielectric interface form tunable interference patterns. We present a simple way how to control the resulting interference patterns both by variation of the angle between two slits and, for a fixed slit geometry, by a proper combination of laser beam polarization and inhomogeneous far-field illumination of the structure. Thus the modulation period of interference patterns has become adjustable and new variable patterns consisting of stripelike and dotlike motifs have been achieved, respectively.

Nobody Is Perfect: ERP Effects Prior to Performance Errors in Musicians Indicate Fast Monitoring Processes

PubMed Central

Maidhof, Clemens; Rieger, Martina; Prinz, Wolfgang; Koelsch, Stefan

2009-01-01

Background One central question in the context of motor control and action monitoring is at what point in time errors can be detected. Previous electrophysiological studies investigating this issue focused on brain potentials elicited after erroneous responses, mainly in simple speeded response tasks. In the present study, we investigated brain potentials before the commission of errors in a natural and complex situation. Methodology/Principal Findings Expert pianists bimanually played scales and patterns while the electroencephalogram (EEG) was recorded. Event-related potentials (ERPs) were computed for correct and incorrect performances. Results revealed differences already 100 ms prior to the onset of a note (i.e., prior to auditory feedback). We further observed that erroneous keystrokes were delayed in time and pressed more slowly. Conclusions Our data reveal neural mechanisms in musicians that are able to detect errors prior to the execution of erroneous movements. The underlying mechanism probably relies on predictive control processes that compare the predicted outcome of an action with the action goal. PMID:19337379

Searching for patterns in remote sensing image databases using neural networks

NASA Technical Reports Server (NTRS)

Paola, Justin D.; Schowengerdt, Robert A.

1995-01-01

We have investigated a method, based on a successful neural network multispectral image classification system, of searching for single patterns in remote sensing databases. While defining the pattern to search for and the feature to be used for that search (spectral, spatial, temporal, etc.) is challenging, a more difficult task is selecting competing patterns to train against the desired pattern. Schemes for competing pattern selection, including random selection and human interpreted selection, are discussed in the context of an example detection of dense urban areas in Landsat Thematic Mapper imagery. When applying the search to multiple images, a simple normalization method can alleviate the problem of inconsistent image calibration. Another potential problem, that of highly compressed data, was found to have a minimal effect on the ability to detect the desired pattern. The neural network algorithm has been implemented using the PVM (Parallel Virtual Machine) library and nearly-optimal speedups have been obtained that help alleviate the long process of searching through imagery.

Effects of alcohol on a problem solving task.

DOT National Transportation Integrated Search

1972-03-01

Twenty subjects were tested on two separate days on a simple problem-solving task. Half of the subjects received alcohol on the first day of testing and half on the second day of testing. A control group of 11 subjects was also tested on two days and...

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.

Examining the influence of a spatially irrelevant working memory load on attentional allocation.

PubMed

McDonnell, Gerald P; Dodd, Michael D

2013-08-01

The present study examined the influence of holding task-relevant gaze cues in working memory during a target detection task. Gaze cues shift attention in gaze-consistent directions, even when they are irrelevant to a primary detection task. It is unclear, however, whether gaze cues need to be perceived online to elicit these effects, or how these effects may be moderated if the gaze cues are relevant to a secondary task. In Experiment 1, participants encoded a face for a subsequent memory task, after which they performed an unrelated target detection task. Critically, gaze direction was irrelevant to the target detection task, but memory for the perceived face was tested at trial conclusion. Surprisingly, participants exhibited inhibition-of-return (IOR) and not facilitation, with slower response times for the gazed-at location. In Experiments 2, presentation duration and cue-target stimulus-onset asynchrony were manipulated and we continued to observe IOR with no early facilitation. Experiment 3 revealed facilitation but not IOR when the memory task was removed; Experiment 4 also revealed facilitation when the gaze cue memory task was replaced with arrows cues. The present experiments provide an important dissociation between perceiving cues online versus holding them in memory as it relates to attentional allocation. 2013 APA, all rights reserved

Characterization of exploratory activity and learning ability of healthy and "schizophrenia-like" rats in a square corridor system (AMBITUS).

PubMed

Horvath, G; Liszli, P; Kekesi, G; Büki, A; Benedek, G

2017-02-01

The rodent tasks with food rewards are useful methods to evaluate memory functions, including hole-board and corridor tests. The AMBITUS system (a square corridor with several food rewards), as a combination of these tests, was developed for the investigation of a variety of parameters associated with exploration and cognitive performance in rodents. Experiments were performed to characterize these behaviors in healthy rats and a new "schizophrenia-like" rat substrain with impaired learning ability to reveal the reliability in tests related to these functions. A square corridor was constructed with equally spaced sites along each wall (4 inside and 4 outside) resulting in 16 side-boxes for food rewards. Photocells at each box recorded the visits into the side-boxes (as exploratory activity), while the eating parameters were obtained from video records. The animals were exposed to two types of tasks repeatedly in two series: all (16) or only the inside (8) boxes (Task 1 or Task 2, respectively) were baited. Most of the rats acquired Task 1, and their performance improved by repetition, but the new substrain showed decreased exploration and learning capacity. The introduction of Task 2 caused prompt preference of the baited inner side-boxes, and gradually improved working and reference memory during the trials. The manual and automated scoring of the visits into the side-boxes showed significant (r=0.97) correlation. The results proved that healthy animals could perform the simple tasks in the square corridor after a few repetitions. The semi-automated AMBITUS system might be appropriate to detect cognitive flexibility after different manipulations, and it provides immediate, online assessment of exploratory behavior of a large number of animals within a short period of time, and it reduces the possibility of experimenter bias. Copyright © 2016 Elsevier Inc. All rights reserved.

Searching for emotion or race: task-irrelevant facial cues have asymmetrical effects.

PubMed

Lipp, Ottmar V; Craig, Belinda M; Frost, Mareka J; Terry, Deborah J; Smith, Joanne R

2014-01-01

Facial cues of threat such as anger and other race membership are detected preferentially in visual search tasks. However, it remains unclear whether these facial cues interact in visual search. If both cues equally facilitate search, a symmetrical interaction would be predicted; anger cues should facilitate detection of other race faces and cues of other race membership should facilitate detection of anger. Past research investigating this race by emotional expression interaction in categorisation tasks revealed an asymmetrical interaction. This suggests that cues of other race membership may facilitate the detection of angry faces but not vice versa. Utilising the same stimuli and procedures across two search tasks, participants were asked to search for targets defined by either race or emotional expression. Contrary to the results revealed in the categorisation paradigm, cues of anger facilitated detection of other race faces whereas differences in race did not differentially influence detection of emotion targets.

Attending to unrelated targets boosts short-term memory for color arrays.

PubMed

Makovski, Tal; Swallow, Khena M; Jiang, Yuhong V

2011-05-01

Detecting a target typically impairs performance in a second, unrelated task. It has been recently reported however, that detecting a target in a stream of distractors can enhance long-term memory of faces and scenes that were presented concurrently with the target (the attentional boost effect). In this study we ask whether target detection also enhances performance in a visual short-term memory task, where capacity limits are severe. Participants performed two tasks at once: a one shot, color change detection task and a letter-detection task. In Experiment 1, a central letter appeared at the same time as 3 or 5 color patches (memory display). Participants encoded the colors and pressed the spacebar if the letter was a T (target). After a short retention interval, a probe display of color patches appeared. Performance on the change detection task was enhanced when a target, rather than a distractor, appeared with the memory display. This effect was not modulated by memory load or the frequency of trials in which a target appeared. However, there was no enhancement when the target appeared at the same time as the probe display (Experiment 2a) or during the memory retention interval (Experiment 2b). Together these results suggest that detecting a target facilitates the encoding of unrelated information into visual short-term memory. Copyright © 2010 Elsevier Ltd. All rights reserved.

Working Memory Integration Processes in Benign Childhood Epilepsy with Centrotemporal Spikes.

PubMed

Kárpáti, Judit; Donauer, Nándor; Somogyi, Eszter; Kónya, Anikó

2015-12-01

Benign epilepsy of childhood with centrotemporal spikes (BECTS) is the most frequent focal epilepsy in children; however, the pattern of affected memory processes remains controversial. Previous studies in BECTS imply deficits in complex working memory tasks, but not in simple modality-specific tasks. We studied working memory processes in children with BECTS by comparing performance in memory binding tasks of different complexities. We compared 17 children with BECTS (aged 6 to 13 years) to 17 healthy children matched for age, sex, and intelligence quotient. We measured spatial and verbal memory components separately and jointly on three single-binding tasks (binding of what and where; what and when; and where and when) and a combined-binding task (integration of what, where, and when). We also evaluated basic visuospatial memory functions with subtests of the Children's Memory Scale, and intellectual abilities with verbal tasks of the Wechsler Intelligence Scale for Children-Fourth Edition and the Raven Progressive Matrices. We found no difference between the BECTS and control groups in single-binding tasks; however, the children with BECTS performed significantly worse on the combined task, which included integration of spatial, verbal, and temporal information. We found no deficits in their intellectual abilities or basic visuospatial memory functions. Children with BECTS may have intact simple maintenance processes of working memory, but difficulty with high-level functions requiring attentional and executive resources. Our findings imply no specific memory dysfunction in BECTS, but suggest difficulties in integrating information within working memory, and possible frontal lobe disturbances.

Learning and inference using complex generative models in a spatial localization task.

PubMed

Bejjanki, Vikranth R; Knill, David C; Aslin, Richard N

2016-01-01

A large body of research has established that, under relatively simple task conditions, human observers integrate uncertain sensory information with learned prior knowledge in an approximately Bayes-optimal manner. However, in many natural tasks, observers must perform this sensory-plus-prior integration when the underlying generative model of the environment consists of multiple causes. Here we ask if the Bayes-optimal integration seen with simple tasks also applies to such natural tasks when the generative model is more complex, or whether observers rely instead on a less efficient set of heuristics that approximate ideal performance. Participants localized a "hidden" target whose position on a touch screen was sampled from a location-contingent bimodal generative model with different variances around each mode. Over repeated exposure to this task, participants learned the a priori locations of the target (i.e., the bimodal generative model), and integrated this learned knowledge with uncertain sensory information on a trial-by-trial basis in a manner consistent with the predictions of Bayes-optimal behavior. In particular, participants rapidly learned the locations of the two modes of the generative model, but the relative variances of the modes were learned much more slowly. Taken together, our results suggest that human performance in a more complex localization task, which requires the integration of sensory information with learned knowledge of a bimodal generative model, is consistent with the predictions of Bayes-optimal behavior, but involves a much longer time-course than in simpler tasks.

PCANet: A Simple Deep Learning Baseline for Image Classification?

PubMed

Chan, Tsung-Han; Jia, Kui; Gao, Shenghua; Lu, Jiwen; Zeng, Zinan; Ma, Yi

2015-12-01

In this paper, we propose a very simple deep learning network for image classification that is based on very basic data processing components: 1) cascaded principal component analysis (PCA); 2) binary hashing; and 3) blockwise histograms. In the proposed architecture, the PCA is employed to learn multistage filter banks. This is followed by simple binary hashing and block histograms for indexing and pooling. This architecture is thus called the PCA network (PCANet) and can be extremely easily and efficiently designed and learned. For comparison and to provide a better understanding, we also introduce and study two simple variations of PCANet: 1) RandNet and 2) LDANet. They share the same topology as PCANet, but their cascaded filters are either randomly selected or learned from linear discriminant analysis. We have extensively tested these basic networks on many benchmark visual data sets for different tasks, including Labeled Faces in the Wild (LFW) for face verification; the MultiPIE, Extended Yale B, AR, Facial Recognition Technology (FERET) data sets for face recognition; and MNIST for hand-written digit recognition. Surprisingly, for all tasks, such a seemingly naive PCANet model is on par with the state-of-the-art features either prefixed, highly hand-crafted, or carefully learned [by deep neural networks (DNNs)]. Even more surprisingly, the model sets new records for many classification tasks on the Extended Yale B, AR, and FERET data sets and on MNIST variations. Additional experiments on other public data sets also demonstrate the potential of PCANet to serve as a simple but highly competitive baseline for texture classification and object recognition.

A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance.

PubMed

von Trapp, Gardiner; Buran, Bradley N; Sen, Kamal; Semple, Malcolm N; Sanes, Dan H

2016-10-26

The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability of the neural response becomes smaller during task performance, thereby improving neural detection thresholds. Copyright © 2016 the authors 0270-6474/16/3611097-10$15.00/0.

A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance

PubMed Central

Buran, Bradley N.; Sen, Kamal; Semple, Malcolm N.; Sanes, Dan H.

2016-01-01

The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. SIGNIFICANCE STATEMENT The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability of the neural response becomes smaller during task performance, thereby improving neural detection thresholds. PMID:27798189

Observer efficiency in free-localization tasks with correlated noise.

PubMed

Abbey, Craig K; Eckstein, Miguel P

2014-01-01

The efficiency of visual tasks involving localization has traditionally been evaluated using forced choice experiments that capitalize on independence across locations to simplify the performance of the ideal observer. However, developments in ideal observer analysis have shown how an ideal observer can be defined for free-localization tasks, where a target can appear anywhere in a defined search region and subjects respond by localizing the target. Since these tasks are representative of many real-world search tasks, it is of interest to evaluate the efficiency of observer performance in them. The central question of this work is whether humans are able to effectively use the information in a free-localization task relative to a similar task where target location is fixed. We use a yes-no detection task at a cued location as the reference for this comparison. Each of the tasks is evaluated using a Gaussian target profile embedded in four different Gaussian noise backgrounds having power-law noise power spectra with exponents ranging from 0 to 3. The free localization task had a square 6.7° search region. We report on two follow-up studies investigating efficiency in a detect-and-localize task, and the effect of processing the white-noise backgrounds. In the fixed-location detection task, we find average observer efficiency ranges from 35 to 59% for the different noise backgrounds. Observer efficiency improves dramatically in the tasks involving localization, ranging from 63 to 82% in the forced localization tasks and from 78 to 92% in the detect-and- localize tasks. Performance in white noise, the lowest efficiency condition, was improved by filtering to give them a power-law exponent of 2. Classification images, used to examine spatial frequency weights for the tasks, show better tuning to ideal weights in the free-localization tasks. The high absolute levels of efficiency suggest that observers are well-adapted to free-localization tasks.

Observer efficiency in free-localization tasks with correlated noise

PubMed Central

Abbey, Craig K.; Eckstein, Miguel P.

2014-01-01

The efficiency of visual tasks involving localization has traditionally been evaluated using forced choice experiments that capitalize on independence across locations to simplify the performance of the ideal observer. However, developments in ideal observer analysis have shown how an ideal observer can be defined for free-localization tasks, where a target can appear anywhere in a defined search region and subjects respond by localizing the target. Since these tasks are representative of many real-world search tasks, it is of interest to evaluate the efficiency of observer performance in them. The central question of this work is whether humans are able to effectively use the information in a free-localization task relative to a similar task where target location is fixed. We use a yes-no detection task at a cued location as the reference for this comparison. Each of the tasks is evaluated using a Gaussian target profile embedded in four different Gaussian noise backgrounds having power-law noise power spectra with exponents ranging from 0 to 3. The free localization task had a square 6.7° search region. We report on two follow-up studies investigating efficiency in a detect-and-localize task, and the effect of processing the white-noise backgrounds. In the fixed-location detection task, we find average observer efficiency ranges from 35 to 59% for the different noise backgrounds. Observer efficiency improves dramatically in the tasks involving localization, ranging from 63 to 82% in the forced localization tasks and from 78 to 92% in the detect-and- localize tasks. Performance in white noise, the lowest efficiency condition, was improved by filtering to give them a power-law exponent of 2. Classification images, used to examine spatial frequency weights for the tasks, show better tuning to ideal weights in the free-localization tasks. The high absolute levels of efficiency suggest that observers are well-adapted to free-localization tasks. PMID:24817854

Switching between simple cognitive tasks: the interaction of top-down and bottom-up factors

NASA Technical Reports Server (NTRS)

Ruthruff, E.; Remington, R. W.; Johnston, J. C.

2001-01-01

How do top-down factors (e.g., task expectancy) and bottom-up factors (e.g., task recency) interact to produce an overall level of task readiness? This question was addressed by factorially manipulating task expectancy and task repetition in a task-switching paradigm. The effects of expectancy and repetition on response time tended to interact underadditively, but only because the traditional binary task-repetition variable lumps together all switch trials, ignoring variation in task lag. When the task-recency variable was scaled continuously, all 4 experiments instead showed additivity between expectancy and recency. The results indicated that expectancy and recency influence different stages of mental processing. One specific possibility (the configuration-execution model) is that task expectancy affects the time required to configure upcoming central operations, whereas task recency affects the time required to actually execute those central operations.

Parallel perceptual enhancement and hierarchic relevance evaluation in an audio-visual conjunction task.

PubMed

Potts, Geoffrey F; Wood, Susan M; Kothmann, Delia; Martin, Laura E

2008-10-21

Attention directs limited-capacity information processing resources to a subset of available perceptual representations. The mechanisms by which attention selects task-relevant representations for preferential processing are not fully known. Triesman and Gelade's [Triesman, A., Gelade, G., 1980. A feature integration theory of attention. Cognit. Psychol. 12, 97-136.] influential attention model posits that simple features are processed preattentively, in parallel, but that attention is required to serially conjoin multiple features into an object representation. Event-related potentials have provided evidence for this model showing parallel processing of perceptual features in the posterior Selection Negativity (SN) and serial, hierarchic processing of feature conjunctions in the Frontal Selection Positivity (FSP). Most prior studies have been done on conjunctions within one sensory modality while many real-world objects have multimodal features. It is not known if the same neural systems of posterior parallel processing of simple features and frontal serial processing of feature conjunctions seen within a sensory modality also operate on conjunctions between modalities. The current study used ERPs and simultaneously presented auditory and visual stimuli in three task conditions: Attend Auditory (auditory feature determines the target, visual features are irrelevant), Attend Visual (visual features relevant, auditory irrelevant), and Attend Conjunction (target defined by the co-occurrence of an auditory and a visual feature). In the Attend Conjunction condition when the auditory but not the visual feature was a target there was an SN over auditory cortex, when the visual but not auditory stimulus was a target there was an SN over visual cortex, and when both auditory and visual stimuli were targets (i.e. conjunction target) there were SNs over both auditory and visual cortex, indicating parallel processing of the simple features within each modality. In contrast, an FSP was present when either the visual only or both auditory and visual features were targets, but not when only the auditory stimulus was a target, indicating that the conjunction target determination was evaluated serially and hierarchically with visual information taking precedence. This indicates that the detection of a target defined by audio-visual conjunction is achieved via the same mechanism as within a single perceptual modality, through separate, parallel processing of the auditory and visual features and serial processing of the feature conjunction elements, rather than by evaluation of a fused multimodal percept.

Active listening: task-dependent plasticity of spectrotemporal receptive fields in primary auditory cortex.

PubMed

Fritz, Jonathan; Elhilali, Mounya; Shamma, Shihab

2005-08-01

Listening is an active process in which attentive focus on salient acoustic features in auditory tasks can influence receptive field properties of cortical neurons. Recent studies showing rapid task-related changes in neuronal spectrotemporal receptive fields (STRFs) in primary auditory cortex of the behaving ferret are reviewed in the context of current research on cortical plasticity. Ferrets were trained on spectral tasks, including tone detection and two-tone discrimination, and on temporal tasks, including gap detection and click-rate discrimination. STRF changes could be measured on-line during task performance and occurred within minutes of task onset. During spectral tasks, there were specific spectral changes (enhanced response to tonal target frequency in tone detection and discrimination, suppressed response to tonal reference frequency in tone discrimination). However, only in the temporal tasks, the STRF was changed along the temporal dimension by sharpening temporal dynamics. In ferrets trained on multiple tasks, distinctive and task-specific STRF changes could be observed in the same cortical neurons in successive behavioral sessions. These results suggest that rapid task-related plasticity is an ongoing process that occurs at a network and single unit level as the animal switches between different tasks and dynamically adapts cortical STRFs in response to changing acoustic demands.

Sequential Dependencies in Driving

ERIC Educational Resources Information Center

Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

2012-01-01

The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

Rethinking the Connection between Working Memory and Language Impairment

ERIC Educational Resources Information Center

Archibald, Lisa M. D.; Harder Griebeling, Katherine

2016-01-01

Background: 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. Aims: To examine the processing function of working memory in children with low language (LL) by employing tasks imposing…

Individual differences in the components of children's and adults' information processing for simple symbolic and non-symbolic numeric decisions.

PubMed

Thompson, Clarissa A; Ratcliff, Roger; McKoon, Gail

2016-10-01

How do speed and accuracy trade off, and what components of information processing develop as children and adults make simple numeric comparisons? Data from symbolic and non-symbolic number tasks were collected from 19 first graders (Mage=7.12 years), 26 second/third graders (Mage=8.20 years), 27 fourth/fifth graders (Mage=10.46 years), and 19 seventh/eighth graders (Mage=13.22 years). The non-symbolic task asked children to decide whether an array of asterisks had a larger or smaller number than 50, and the symbolic task asked whether a two-digit number was greater than or less than 50. We used a diffusion model analysis to estimate components of processing in tasks from accuracy, correct and error response times, and response time (RT) distributions. Participants who were accurate on one task were accurate on the other task, and participants who made fast decisions on one task made fast decisions on the other task. Older participants extracted a higher quality of information from the stimulus arrays, were more willing to make a decision, and were faster at encoding, transforming the stimulus representation, and executing their responses. Individual participants' accuracy and RTs were uncorrelated. Drift rate and boundary settings were significantly related across tasks, but they were unrelated to each other. Accuracy was mainly determined by drift rate, and RT was mainly determined by boundary separation. We concluded that RT and accuracy operate largely independently. Copyright © 2016 Elsevier Inc. All rights reserved.

Differences in arithmetic performance between Chinese and German adults are accompanied by differences in processing of non-symbolic numerical magnitude

PubMed Central

Lonnemann, Jan; Li, Su; Zhao, Pei; Li, Peng; Linkersdörfer, Janosch; Lindberg, Sven; Hasselhorn, Marcus; Yan, Song

2017-01-01

Human beings are assumed to possess an approximate number system (ANS) dedicated to extracting and representing approximate numerical magnitude information. The ANS is assumed to be fundamental to arithmetic learning and has been shown to be associated with arithmetic performance. It is, however, still a matter of debate whether better arithmetic skills are reflected in the ANS. To address this issue, Chinese and German adults were compared regarding their performance in simple arithmetic tasks and in a non-symbolic numerical magnitude comparison task. Chinese participants showed a better performance in solving simple arithmetic tasks and faster reaction times in the non-symbolic numerical magnitude comparison task without making more errors than their German peers. These differences in performance could not be ascribed to differences in general cognitive abilities. Better arithmetic skills were thus found to be accompanied by a higher speed of retrieving non-symbolic numerical magnitude knowledge but not by a higher precision of non-symbolic numerical magnitude representations. The group difference in the speed of retrieving non-symbolic numerical magnitude knowledge was fully mediated by the performance in arithmetic tasks, suggesting that arithmetic skills shape non-symbolic numerical magnitude processing skills. PMID:28384191

Sustained attention in language production: an individual differences investigation.

PubMed

Jongman, Suzanne R; Roelofs, Ardi; Meyer, Antje S

2015-01-01

Whereas it has long been assumed that most linguistic processes underlying language production happen automatically, accumulating evidence suggests that these processes do require some form of attention. Here we investigated the contribution of sustained attention: the ability to maintain alertness over time. In Experiment 1, participants' sustained attention ability was measured using auditory and visual continuous performance tasks. Subsequently, employing a dual-task procedure, participants described pictures using simple noun phrases and performed an arrow-discrimination task while their vocal and manual response times (RTs) and the durations of their gazes to the pictures were measured. Earlier research has demonstrated that gaze duration reflects language planning processes up to and including phonological encoding. The speakers' sustained attention ability correlated with the magnitude of the tail of the vocal RT distribution, reflecting the proportion of very slow responses, but not with individual differences in gaze duration. This suggests that sustained attention was most important after phonological encoding. Experiment 2 showed that the involvement of sustained attention was significantly stronger in a dual-task situation (picture naming and arrow discrimination) than in simple naming. Thus, individual differences in maintaining attention on the production processes become especially apparent when a simultaneous second task also requires attentional resources.

Efficient mental workload estimation using task-independent EEG features.

PubMed

Roy, R N; Charbonnier, S; Campagne, A; Bonnet, S

2016-04-01

Mental workload is frequently estimated by EEG-based mental state monitoring systems. Usually, these systems use spectral markers and event-related potentials (ERPs). To our knowledge, no study has directly compared their performance for mental workload assessment, nor evaluated the stability in time of these markers and of the performance of the associated mental workload estimators.  This study proposes a comparison of two processing chains, one based on the power in five frequency bands, and one based on ERPs, both including a spatial filtering step (respectively CSP and CCA), an FLDA classification and a 10-fold cross-validation. To get closer to a real life implementation, spectral markers were extracted from a short window (i.e. towards reactive systems) that did not include any motor activity and the analyzed ERPs were elicited by a task-independent probe that required a reflex-like answer (i.e. close to the ones required by dead man's vigilance devices). The data were acquired from 20 participants who performed a Sternberg memory task for 90 min (i.e. 2/6 digits to memorize) inside which a simple detection task was inserted. The results were compared both when the testing was performed at the beginning and end of the session. Both chains performed significantly better than random; however the one based on the spectral markers had a low performance (60%) and was not stable in time. Conversely, the ERP-based chain gave very high results (91%) and was stable in time. This study demonstrates that an efficient and stable in time workload estimation can be achieved using task-independent spatially filtered ERPs elicited in a minimally intrusive manner.

Efficient mental workload estimation using task-independent EEG features

NASA Astrophysics Data System (ADS)

Roy, R. N.; Charbonnier, S.; Campagne, A.; Bonnet, S.

2016-04-01

Objective. Mental workload is frequently estimated by EEG-based mental state monitoring systems. Usually, these systems use spectral markers and event-related potentials (ERPs). To our knowledge, no study has directly compared their performance for mental workload assessment, nor evaluated the stability in time of these markers and of the performance of the associated mental workload estimators. This study proposes a comparison of two processing chains, one based on the power in five frequency bands, and one based on ERPs, both including a spatial filtering step (respectively CSP and CCA), an FLDA classification and a 10-fold cross-validation. Approach. To get closer to a real life implementation, spectral markers were extracted from a short window (i.e. towards reactive systems) that did not include any motor activity and the analyzed ERPs were elicited by a task-independent probe that required a reflex-like answer (i.e. close to the ones required by dead man’s vigilance devices). The data were acquired from 20 participants who performed a Sternberg memory task for 90 min (i.e. 2/6 digits to memorize) inside which a simple detection task was inserted. The results were compared both when the testing was performed at the beginning and end of the session. Main results. Both chains performed significantly better than random; however the one based on the spectral markers had a low performance (60%) and was not stable in time. Conversely, the ERP-based chain gave very high results (91%) and was stable in time. Significance. This study demonstrates that an efficient and stable in time workload estimation can be achieved using task-independent spatially filtered ERPs elicited in a minimally intrusive manner.

Playing checkers: detection and eye hand coordination in simulated prosthetic vision

NASA Astrophysics Data System (ADS)

Dagnelie, Gislin; Walter, Matthias; Yang, Liancheng

2006-09-01

In order to assess the potential for visual inspection and eye hand coordination without tactile feedback under conditions that may be available to future retinal prosthesis wearers, we studied the ability of sighted individuals to act upon pixelized visual information at very low resolution, equivalent to 20/2400 visual acuity. Live images from a head-mounted camera were low-pass filtered and presented in a raster of 6 × 10 circular Gaussian dots. Subjects could either freely move their gaze across the raster (free-viewing condition) or the raster position was locked to the subject's gaze by means of video-based pupil tracking (gaze-locked condition). Four normally sighted and one severely visually impaired subject with moderate nystagmus participated in a series of four experiments. Subjects' task was to count 1 to 16 white fields randomly distributed across an otherwise black checkerboard (counting task) or to place a black checker on each of the white fields (placing task). We found that all subjects were capable of learning both tasks after varying amounts of practice, both in the free-viewing and in the gaze-locked conditions. Normally sighted subjects all reached very similar performance levels independent of the condition. The practiced performance level of the visually impaired subject in the free-viewing condition was indistinguishable from that of the normally sighted subjects, but required approximately twice the amount of time to place checkers in the gaze-locked condition; this difference is most likely attributable to this subject's nystagmus. Thus, if early retinal prosthesis wearers can achieve crude form vision, then on the basis of these results they too should be able to perform simple eye hand coordination tasks without tactile feedback.

Detection of P300 waves in single trials by the wavelet transform (WT).

PubMed

Demiralp, T; Ademoglu, A; Schürmann, M; Başar-Eroglu, C; Başar, E

1999-01-01

The P300 response is conventionally obtained by averaging the responses to the task-relevant (target) stimuli of the oddball paradigm. However, it is well known that cognitive ERP components show a high variability due to changes of cognitive state during an experimental session. With simple tasks such changes may not be demonstrable by the conventional method of averaging the sweeps chosen according to task-relevance. Therefore, the present work employed a response-based classification procedure to choose the trials containing the P300 component from the whole set of sweeps of an auditory oddball paradigm. For this purpose, the most significant response property reflecting the P300 wave was identified by using the wavelet transform (WT). The application of a 5 octave quadratic B-spline-WT on single sweeps yielded discrete coefficients in each octave with an appropriate time resolution for each frequency range. The main feature indicating a P300 response was the positivity of the 4th delta (0.5-4 Hz) coefficient (310-430 ms) after stimulus onset. The average of selected single sweeps from the whole set of data according to this criterion yielded more enhanced P300 waves compared with the average of the target responses, and the average of the remaining sweeps showed a significantly smaller positivity in the P300 latency range compared with the average of the non-target responses. The combination of sweeps classified according to the task-based and response-based criteria differed significantly. This suggests an influence of changes in cognitive state on the presence of the P300 wave which cannot be assessed by task performance alone. Copyright 1999 Academic Press.

Explicit Scaffolding Increases Simple Helping in Younger Infants

ERIC Educational Resources Information Center

Dahl, Audun; Satlof-Bedrick, Emma S.; Hammond, Stuart I.; Drummond, Jesse K.; Waugh, Whitney E.; Brownell, Celia A.

2017-01-01

Infants become increasingly helpful during the second year. We investigated experimentally whether adults' explicit scaffolding influences this development. Infants (N = 69, 13-18 months old) participated in a series of simple helping tasks. Half of infants received explicit scaffolding (encouragement and praise), whereas the other half did not.…

A Simple Estimation Method for Aggregate Government Outsourcing

ERIC Educational Resources Information Center

Minicucci, Stephen; Donahue, John D.

2004-01-01

The scholarly and popular debate on the delegation to the private sector of governmental tasks rests on an inadequate empirical foundation, as no systematic data are collected on direct versus indirect service delivery. We offer a simple method for approximating levels of service outsourcing, based on relatively straightforward combinations of and…

Reaction Time is a Marker of Early Cognitive and Behavioral Alterations in Pure Cerebral Small Vessel Disease.

PubMed

Jouvent, Eric; Reyes, Sonia; De Guio, François; Chabriat, Hugues

2015-01-01

The assessment of early and subtle cognitive and behavioral effects of cerebral small vessel disease (SVD) requires specific and long-lasting evaluations performed by experienced neuropsychologists. Simpler tools would be helpful for daily clinical practice. To determine whether a simple reaction time task that lasts 5 minutes and can be performed without external supervision on any tablet or laptop can be used as a proxy of early cognitive and behavioral alterations in CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), a monogenic form of pure SVD related to NOTCH3 mutations. Twenty-two genetically confirmed patients with CADASIL having preserved global cognitive abilities and without disability (MMSE >24 and modified Rankin's scale ≤1) were compared to 29 age-and-gender matched controls to determine group differences according to: 1) conventional neuropsychological and behavioral testing; 2) a computerized battery evaluating reaction time, processing speed, and executive functions. In a second step, correlations between reaction time and cognitive and behavioral alterations detected using both conventional and computerized testing were tested in patients. Reaction time was significantly higher in patients than in controls (mean in patients: 283 ms - in controls: 254 ms, p = 0.03). In patients, reaction time was significantly associated with conventional and chronometric tests of executive functions, working memory, and apathy. Reaction time obtained using a very simple task may serve as a proxy of early cognitive and behavioral alterations in SVD and could be easily used in daily clinical practice.

Changes in spinal reflex excitability associated with motor sequence learning.

PubMed

Lungu, Ovidiu; Frigon, Alain; Piché, Mathieu; Rainville, Pierre; Rossignol, Serge; Doyon, Julien

2010-05-01

There is ample evidence that motor sequence learning is mediated by changes in brain activity. Yet the question of whether this form of learning elicits changes detectable at the spinal cord level has not been addressed. To date, studies in humans have revealed that spinal reflex activity may be altered during the acquisition of various motor skills, but a link between motor sequence learning and changes in spinal excitability has not been demonstrated. To address this issue, we studied the modulation of H-reflex amplitude evoked in the flexor carpi radialis muscle of 14 healthy individuals between blocks of movements that involved the implicit acquisition of a sequence versus other movements that did not require learning. Each participant performed the task in three conditions: "sequence"-externally triggered, repeating and sequential movements, "random"-similar movements, but performed in an arbitrary order, and "simple"- involving alternating movements in a left-right or up-down direction only. When controlling for background muscular activity, H-reflex amplitude was significantly more reduced in the sequence (43.8 +/- 1.47%. mean +/- SE) compared with the random (38.2 +/- 1.60%) and simple (31.5 +/- 1.82%) conditions, while the M-response was not different across conditions. Furthermore, H-reflex changes were observed from the beginning of the learning process up to when subjects reached asymptotic performance on the motor task. Changes also persisted for >60 s after motor activity ceased. Such findings suggest that the excitability in some spinal reflex circuits is altered during the implicit learning process of a new motor sequence.

A Mechanism for Error Detection in Speeded Response Time Tasks

ERIC Educational Resources Information Center

Holroyd, Clay B.; Yeung, Nick; Coles, Michael G. H.; Cohen, Jonathan D.

2005-01-01

The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors…

Motor heuristics and embodied choices: how to choose and act.

PubMed

Raab, Markus

2017-08-01

Human performance requires choosing what to do and how to do it. The goal of this theoretical contribution is to advance understanding of how the motor and cognitive components of choices are intertwined. From a holistic perspective I extend simple heuristics that have been tested in cognitive tasks to motor tasks, coining the term motor heuristics. Similarly I extend the concept of embodied cognition, that has been tested in simple sensorimotor processes changing decisions, to complex sport behavior coining the term embodied choices. Thus both motor heuristics and embodied choices explain complex behavior such as studied in sport and exercise psychology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Verifying the Modal Logic Cube Is an Easy Task (For Higher-Order Automated Reasoners)

NASA Astrophysics Data System (ADS)

Benzmüller, Christoph

Prominent logics, including quantified multimodal logics, can be elegantly embedded in simple type theory (classical higher-order logic). Furthermore, off-the-shelf reasoning systems for simple type type theory exist that can be uniformly employed for reasoning within and about embedded logics. In this paper we focus on reasoning about modal logics and exploit our framework for the automated verification of inclusion and equivalence relations between them. Related work has applied first-order automated theorem provers for the task. Our solution achieves significant improvements, most notably, with respect to elegance and simplicity of the problem encodings as well as with respect to automation performance.

The time course of corticospinal excitability during a simple reaction time task.

PubMed

Kennefick, Michael; Maslovat, Dana; Carlsen, Anthony N

2014-01-01

The production of movement in a simple reaction time task can be separated into two time periods: the foreperiod, which is thought to include preparatory processes, and the reaction time interval, which includes initiation processes. To better understand these processes, transcranial magnetic stimulation has been used to probe corticospinal excitability at various time points during response preparation and initiation. Previous research has shown that excitability decreases prior to the "go" stimulus and increases following the "go"; however these two time frames have been examined independently. The purpose of this study was to measure changes in CE during both the foreperiod and reaction time interval in a single experiment, relative to a resting baseline level. Participants performed a button press movement in a simple reaction time task and excitability was measured during rest, the foreperiod, and the reaction time interval. Results indicated that during the foreperiod, excitability levels quickly increased from baseline with the presentation of the warning signal, followed by a period of stable excitability leading up to the "go" signal, and finally a rapid increase in excitability during the reaction time interval. This excitability time course is consistent with neural activation models that describe movement preparation and response initiation.

Theory of mind in schizophrenia: exploring neural mechanisms of belief attribution.

PubMed

Lee, Junghee; Quintana, Javier; Nori, Poorang; Green, Michael F

2011-01-01

Although previous behavioral studies have shown that schizophrenia patients have impaired theory of mind (ToM), the neural mechanisms associated with this impairment are poorly understood. This study aimed to identify the neural mechanisms of ToM in schizophrenia, using functional magnetic resonance imaging (fMRI) with a belief attribution task. In the scanner, 12 schizophrenia patients and 13 healthy control subjects performed the belief attribution task with three conditions: a false belief condition, a false photograph condition, and a simple reading condition. For the false belief versus simple reading conditions, schizophrenia patients showed reduced neural activation in areas including the temporoparietal junction (TPJ) and medial prefrontal cortex (MPFC) compared with controls. Further, during the false belief versus false photograph conditions, we observed increased activations in the TPJ and the MPFC in healthy controls, but not in schizophrenia patients. For the false photograph versus simple reading condition, both groups showed comparable neural activations. Schizophrenia patients showed reduced task-related activation in the TPJ and the MPFC during the false belief condition compared with controls, but not for the false photograph condition. This pattern suggests that reduced activation in these regions is associated with, and specific to, impaired ToM in schizophrenia.

No psychological effect of color context in a low level vision task

PubMed Central

Pedley, Adam; Wade, Alex R

2013-01-01

Background: A remarkable series of recent papers have shown that colour can influence performance in cognitive tasks. In particular, they suggest that viewing a participant number printed in red ink or other red ancillary stimulus elements improves performance in tasks requiring local processing and impedes performance in tasks requiring global processing whilst the reverse is true for the colour blue. The tasks in these experiments require high level cognitive processing such as analogy solving or remote association tests and the chromatic effect on local vs. global processing is presumed to involve widespread activation of the autonomic nervous system. If this is the case, we might expect to see similar effects on all local vs. global task comparisons. To test this hypothesis, we asked whether chromatic cues also influence performance in tasks involving low level visual feature integration. Methods: Subjects performed either local (contrast detection) or global (form detection) tasks on achromatic dynamic Glass pattern stimuli. Coloured instructions, target frames and fixation points were used to attempt to bias performance to different task types. Based on previous literature, we hypothesised that red cues would improve performance in the (local) contrast detection task but would impede performance in the (global) form detection task.  Results: A two-way, repeated measures, analysis of covariance (2×2 ANCOVA) with gender as a covariate, revealed no influence of colour on either task, F(1,29) = 0.289, p = 0.595, partial η 2 = 0.002. Additional analysis revealed no significant differences in only the first attempts of the tasks or in the improvement in performance between trials. Discussion: We conclude that motivational processes elicited by colour perception do not influence neuronal signal processing in the early visual system, in stark contrast to their putative effects on processing in higher areas. PMID:25075280

No psychological effect of color context in a low level vision task.

PubMed

Pedley, Adam; Wade, Alex R

2013-01-01

A remarkable series of recent papers have shown that colour can influence performance in cognitive tasks. In particular, they suggest that viewing a participant number printed in red ink or other red ancillary stimulus elements improves performance in tasks requiring local processing and impedes performance in tasks requiring global processing whilst the reverse is true for the colour blue. The tasks in these experiments require high level cognitive processing such as analogy solving or remote association tests and the chromatic effect on local vs. global processing is presumed to involve widespread activation of the autonomic nervous system. If this is the case, we might expect to see similar effects on all local vs. global task comparisons. To test this hypothesis, we asked whether chromatic cues also influence performance in tasks involving low level visual feature integration. Subjects performed either local (contrast detection) or global (form detection) tasks on achromatic dynamic Glass pattern stimuli. Coloured instructions, target frames and fixation points were used to attempt to bias performance to different task types. Based on previous literature, we hypothesised that red cues would improve performance in the (local) contrast detection task but would impede performance in the (global) form detection task.  A two-way, repeated measures, analysis of covariance (2×2 ANCOVA) with gender as a covariate, revealed no influence of colour on either task, F(1,29) = 0.289, p = 0.595, partial η (2) = 0.002. Additional analysis revealed no significant differences in only the first attempts of the tasks or in the improvement in performance between trials. We conclude that motivational processes elicited by colour perception do not influence neuronal signal processing in the early visual system, in stark contrast to their putative effects on processing in higher areas.

An Approach to Operational Analysis: Doctrinal Task Decomposition

DTIC Science & Technology

2016-08-04

Once the unit is selected , CATS will output all of the doctrinal collective tasks associated with the unit. Currently, CATS outputs this information...Army unit are controlled data items, but for explanation purposes consider this simple example using a restaurant as the unit of interest. Table 1...shows an example Task Model for a restaurant using language and format similar to what CATS provides. Only 3 levels are shown in the example, but

Rules and more rules: the effects of multiple tasks, extensive training, and aging on task-switching performance.

PubMed

Buchler, Norbou G; Hoyer, William J; Cerella, John

2008-06-01

Task-switching performance was assessed in young and older adults as a function of the number of task sets to be actively maintained in memory (varied from 1 to 4) over the course of extended training (5 days). Each of the four tasks required the execution of a simple computational algorithm, which was instantaneously cued by the color of the two-digit stimulus. Tasks were presented in pure (task set size 1) and mixed blocks (task set sizes 2, 3, 4), and the task sequence was unpredictable. By considering task switching beyond two tasks, we found evidence for a cognitive control system that is not overwhelmed by task set size load manipulations. Extended training eliminated age effects in task-switching performance, even when the participants had to manage the execution of up to four tasks. The results are discussed in terms of current theories of cognitive control, including task set inertia and production system postulates.

Impaired visual recognition of biological motion in schizophrenia.

PubMed

Kim, Jejoong; Doop, Mikisha L; Blake, Randolph; Park, Sohee

2005-09-15

Motion perception deficits have been suggested to be an important feature of schizophrenia but the behavioral consequences of such deficits are unknown. Biological motion refers to the movements generated by living beings. The human visual system rapidly and effortlessly detects and extracts socially relevant information from biological motion. A deficit in biological motion perception may have significant consequences for detecting and interpreting social information. Schizophrenia patients and matched healthy controls were tested on two visual tasks: recognition of human activity portrayed in point-light animations (biological motion task) and a perceptual control task involving detection of a grouped figure against the background noise (global-form task). Both tasks required detection of a global form against background noise but only the biological motion task required the extraction of motion-related information. Schizophrenia patients performed as well as the controls in the global-form task, but were significantly impaired on the biological motion task. In addition, deficits in biological motion perception correlated with impaired social functioning as measured by the Zigler social competence scale [Zigler, E., Levine, J. (1981). Premorbid competence in schizophrenia: what is being measured? Journal of Consulting and Clinical Psychology, 49, 96-105.]. The deficit in biological motion processing, which may be related to the previously documented deficit in global motion processing, could contribute to abnormal social functioning in schizophrenia.

Constrained sampling experiments reveal principles of detection in natural scenes.

PubMed

Sebastian, Stephen; Abrams, Jared; Geisler, Wilson S

2017-07-11

A fundamental everyday visual task is to detect target objects within a background scene. Using relatively simple stimuli, vision science has identified several major factors that affect detection thresholds, including the luminance of the background, the contrast of the background, the spatial similarity of the background to the target, and uncertainty due to random variations in the properties of the background and in the amplitude of the target. Here we use an experimental approach based on constrained sampling from multidimensional histograms of natural stimuli, together with a theoretical analysis based on signal detection theory, to discover how these factors affect detection in natural scenes. We sorted a large collection of natural image backgrounds into multidimensional histograms, where each bin corresponds to a particular luminance, contrast, and similarity. Detection thresholds were measured for a subset of bins spanning the space, where a natural background was randomly sampled from a bin on each trial. In low-uncertainty conditions, both the background bin and the amplitude of the target were fixed, and, in high-uncertainty conditions, they varied randomly on each trial. We found that thresholds increase approximately linearly along all three dimensions and that detection accuracy is unaffected by background bin and target amplitude uncertainty. The results are predicted from first principles by a normalized matched-template detector, where the dynamic normalizing gain factor follows directly from the statistical properties of the natural backgrounds. The results provide an explanation for classic laws of psychophysics and their underlying neural mechanisms.

Limits of Spatial Attention in Three-Dimensional Space and Dual-task Driving Performance

PubMed Central

Andersen, George J.; Ni, Rui; Bian, Zheng; Kang, Julie

2010-01-01

The present study examined the limits of spatial attention while performing two driving relevant tasks that varied in depth. The first task was to maintain a fixed headway distance behind a lead vehicle that varied speed. The second task was to detect a light-change target in an array of lights located above the roadway. In Experiment 1 the light detection task required drivers to encode color and location. The results indicated that reaction time to detect a light-change target increased and accuracy decreased as a function of the horizontal location of the light-change target and as a function of the distance from the driver. In a second experiment the light change task was changed to a singleton search (detect the onset of a yellow light) and the workload of the car following task was systematically varied. The results of Experiment 2 indicated that RT increased as a function of task workload, the 2D position of the light-change target and the distance of the light-change target. A multiple regression analysis indicated that the effect of distance on light detection performance was not due to changes in the projected size of the light target. In Experiment 3 we found that the distance effect in detecting a light change could not be explained by the location of eye fixations. The results demonstrate that when drivers attend to a roadway scene attention is limited in three-dimensional space. These results have important implications for developing tests for assessing crash risk among drivers as well as the design of in vehicle technologies such as head-up displays. PMID:21094336

Improving surface EMG burst detection in infrahyoid muscles during swallowing using digital filters and discrete wavelet analysis.

PubMed

Restrepo-Agudelo, Sebastian; Roldan-Vasco, Sebastian; Ramirez-Arbelaez, Lina; Cadavid-Arboleda, Santiago; Perez-Giraldo, Estefania; Orozco-Duque, Andres

2017-08-01

The visual inspection is a widely used method for evaluating the surface electromyographic signal (sEMG) during deglutition, a process highly dependent of the examiners expertise. It is desirable to have a less subjective and automated technique to improve the onset detection in swallowing related muscles, which have a low signal-to-noise ratio. In this work, we acquired sEMG measured in infrahyoid muscles with high baseline noise of ten healthy adults during water swallowing tasks. Two methods were applied to find the combination of cutoff frequencies that achieve the most accurate onset detection: discrete wavelet decomposition based method and fixed steps variations of low and high cutoff frequencies of a digital bandpass filter. Teager-Kaiser Energy operator, root mean square and simple threshold method were applied for both techniques. Results show a narrowing of the effective bandwidth vs. the literature recommended parameters for sEMG acquisition. Both level 3 decomposition with mother wavelet db4 and bandpass filter with cutoff frequencies between 130 and 180Hz were optimal for onset detection in infrahyoid muscles. The proposed methodologies recognized the onset time with predictive power above 0.95, that is similar to previous findings but in larger and more superficial muscles in limbs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Support Vector Feature Selection for Early Detection of Anastomosis Leakage From Bag-of-Words in Electronic Health Records.

PubMed

Soguero-Ruiz, Cristina; Hindberg, Kristian; Rojo-Alvarez, Jose Luis; Skrovseth, Stein Olav; Godtliebsen, Fred; Mortensen, Kim; Revhaug, Arthur; Lindsetmo, Rolv-Ole; Augestad, Knut Magne; Jenssen, Robert

2016-09-01

The free text in electronic health records (EHRs) conveys a huge amount of clinical information about health state and patient history. Despite a rapidly growing literature on the use of machine learning techniques for extracting this information, little effort has been invested toward feature selection and the features' corresponding medical interpretation. In this study, we focus on the task of early detection of anastomosis leakage (AL), a severe complication after elective surgery for colorectal cancer (CRC) surgery, using free text extracted from EHRs. We use a bag-of-words model to investigate the potential for feature selection strategies. The purpose is earlier detection of AL and prediction of AL with data generated in the EHR before the actual complication occur. Due to the high dimensionality of the data, we derive feature selection strategies using the robust support vector machine linear maximum margin classifier, by investigating: 1) a simple statistical criterion (leave-one-out-based test); 2) an intensive-computation statistical criterion (Bootstrap resampling); and 3) an advanced statistical criterion (kernel entropy). Results reveal a discriminatory power for early detection of complications after CRC (sensitivity 100%; specificity 72%). These results can be used to develop prediction models, based on EHR data, that can support surgeons and patients in the preoperative decision making phase.

Robust online tracking via adaptive samples selection with saliency detection

NASA Astrophysics Data System (ADS)

Yan, Jia; Chen, Xi; Zhu, QiuPing

2013-12-01

Online tracking has shown to be successful in tracking of previously unknown objects. However, there are two important factors which lead to drift problem of online tracking, the one is how to select the exact labeled samples even when the target locations are inaccurate, and the other is how to handle the confusors which have similar features with the target. In this article, we propose a robust online tracking algorithm with adaptive samples selection based on saliency detection to overcome the drift problem. To deal with the problem of degrading the classifiers using mis-aligned samples, we introduce the saliency detection method to our tracking problem. Saliency maps and the strong classifiers are combined to extract the most correct positive samples. Our approach employs a simple yet saliency detection algorithm based on image spectral residual analysis. Furthermore, instead of using the random patches as the negative samples, we propose a reasonable selection criterion, in which both the saliency confidence and similarity are considered with the benefits that confusors in the surrounding background are incorporated into the classifiers update process before the drift occurs. The tracking task is formulated as a binary classification via online boosting framework. Experiment results in several challenging video sequences demonstrate the accuracy and stability of our tracker.

Eye movements show similar adaptations in temporal coordination to movement planning conditions in both people with and without cerebral palsy.

PubMed

Payne, Alexander R; Plimmer, Beryl; McDaid, Andrew; Davies, T Claire

2017-05-01

The effects of cerebral palsy on movement planning for simple reaching tasks are not well understood. Movement planning is complex and entails many processes which could be affected. This study specifically sought to evaluate integrating task information, decoupling movements, and adjusting to altered mapping. For a reaching task, the asynchrony between the eye onset and the hand onset was measured across different movement planning conditions for participants with and without cerebral palsy. Previous research shows people without cerebral palsy vary this temporal coordination for different planning conditions. Our measurements show similar adaptations in temporal coordination for groups with and without cerebral palsy, to three of the four variations in planning condition tested. However, movement durations were still longer for the participants with cerebral palsy. Hence for simple goal-directed reaching, movement execution problems appear to limit activity more than movement planning deficits.

From homeostasis to behavior: Balanced activity in an exploration of embodied dynamic environmental-neural interaction.

PubMed

Hellyer, Peter John; Clopath, Claudia; Kehagia, Angie A; Turkheimer, Federico E; Leech, Robert

2017-08-01

In recent years, there have been many computational simulations of spontaneous neural dynamics. Here, we describe a simple model of spontaneous neural dynamics that controls an agent moving in a simple virtual environment. These dynamics generate interesting brain-environment feedback interactions that rapidly destabilize neural and behavioral dynamics demonstrating the need for homeostatic mechanisms. We investigate roles for homeostatic plasticity both locally (local inhibition adjusting to balance excitatory input) as well as more globally (regional "task negative" activity that compensates for "task positive", sensory input in another region) balancing neural activity and leading to more stable behavior (trajectories through the environment). Our results suggest complementary functional roles for both local and macroscale mechanisms in maintaining neural and behavioral dynamics and a novel functional role for macroscopic "task-negative" patterns of activity (e.g., the default mode network).

Modeling and predicting historical volatility in exchange rate markets

NASA Astrophysics Data System (ADS)

Lahmiri, Salim

2017-04-01

Volatility modeling and forecasting of currency exchange rate is an important task in several business risk management tasks; including treasury risk management, derivatives pricing, and portfolio risk evaluation. The purpose of this study is to present a simple and effective approach for predicting historical volatility of currency exchange rate. The approach is based on a limited set of technical indicators as inputs to the artificial neural networks (ANN). To show the effectiveness of the proposed approach, it was applied to forecast US/Canada and US/Euro exchange rates volatilities. The forecasting results show that our simple approach outperformed the conventional GARCH and EGARCH with different distribution assumptions, and also the hybrid GARCH and EGARCH with ANN in terms of mean absolute error, mean of squared errors, and Theil's inequality coefficient. Because of the simplicity and effectiveness of the approach, it is promising for US currency volatility prediction tasks.

Supporting dynamic change detection: using the right tool for the task.

PubMed

Vallières, Benoît R; Hodgetts, Helen M; Vachon, François; Tremblay, Sébastien

2016-01-01

Detecting task-relevant changes in a visual scene is necessary for successfully monitoring and managing dynamic command and control situations. Change blindness-the failure to notice visual changes-is an important source of human error. Change History EXplicit (CHEX) is a tool developed to aid change detection and maintain situation awareness; and in the current study we test the generality of its ability to facilitate the detection of changes when this subtask is embedded within a broader dynamic decision-making task. A multitasking air-warfare simulation required participants to perform radar-based subtasks, for which change detection was a necessary aspect of the higher-order goal of protecting one's own ship. In this task, however, CHEX rendered the operator even more vulnerable to attentional failures in change detection and increased perceived workload. Such support was only effective when participants performed a change detection task without concurrent subtasks. Results are interpreted in terms of the NSEEV model of attention behavior (Steelman, McCarley, & Wickens, Hum. Factors 53:142-153, 2011; J. Exp. Psychol. Appl. 19:403-419, 2013), and suggest that decision aids for use in multitasking contexts must be designed to fit within the available workload capacity of the user so that they may truly augment cognition.

Driver Vigilance in Automated Vehicles: Hazard Detection Failures Are a Matter of Time.

PubMed

Greenlee, Eric T; DeLucia, Patricia R; Newton, David C

2018-06-01

The primary aim of the current study was to determine whether monitoring the roadway for hazards during automated driving results in a vigilance decrement. Although automated vehicles are relatively novel, the nature of human-automation interaction within them has the classic hallmarks of a vigilance task. Drivers must maintain attention for prolonged periods of time to detect and respond to rare and unpredictable events, for example, roadway hazards that automation may be ill equipped to detect. Given the similarity with traditional vigilance tasks, we predicted that drivers of a simulated automated vehicle would demonstrate a vigilance decrement in hazard detection performance. Participants "drove" a simulated automated vehicle for 40 minutes. During that time, their task was to monitor the roadway for roadway hazards. As predicted, hazard detection rate declined precipitously, and reaction times slowed as the drive progressed. Further, subjective ratings of workload and task-related stress indicated that sustained monitoring is demanding and distressing and it is a challenge to maintain task engagement. Monitoring the roadway for potential hazards during automated driving results in workload, stress, and performance decrements similar to those observed in traditional vigilance tasks. To the degree that vigilance is required of automated vehicle drivers, performance errors and associated safety risks are likely to occur as a function of time on task. Vigilance should be a focal safety concern in the development of vehicle automation.

Improved Targeting Through Collaborative Decision-Making and Brain Computer Interfaces

NASA Technical Reports Server (NTRS)

Stoica, Adrian; Barrero, David F.; McDonald-Maier, Klaus

2013-01-01

This paper reports a first step toward a brain-computer interface (BCI) for collaborative targeting. Specifically, we explore, from a broad perspective, how the collaboration of a group of people can increase the performance on a simple target identification task. To this end, we requested a group of people to identify the location and color of a sequence of targets appearing on the screen and measured the time and accuracy of the response. The individual results are compared to a collective identification result determined by simple majority voting, with random choice in case of drawn. The results are promising, as the identification becomes significantly more reliable even with this simple voting and a small number of people (either odd or even number) involved in the decision. In addition, the paper briefly analyzes the role of brain-computer interfaces in collaborative targeting, extending the targeting task by using a BCI instead of a mechanical response.

The acquisition of simple associations as observed in color-word contingency learning.

PubMed

Lin, Olivia Y-H; MacLeod, Colin M

2018-01-01

Three experiments investigated the learning of simple associations in a color-word contingency task. Participants responded manually to the print colors of 3 words, with each word associated strongly to 1 of the 3 colors and weakly to the other 2 colors. Despite the words being irrelevant, response times to high-contingency stimuli and to low-contingency stimuli quickly diverged. This high-low difference remained quite constant over successive blocks of trials, evidence of stable contingency learning. Inclusion of a baseline condition-an item having no color-word contingency-permitted separation of the contingency learning effect into 2 components: a cost due to low contingency and a benefit due to high contingency. Both cost and benefit were quick to acquire, quick to extinguish, and quick to reacquire. The color-word contingency task provides a simple way to directly study the learning of associations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Pre-trained D-CNN models for detecting complex events in unconstrained videos

NASA Astrophysics Data System (ADS)

Robinson, Joseph P.; Fu, Yun

2016-05-01

Rapid event detection faces an emergent need to process large videos collections; whether surveillance videos or unconstrained web videos, the ability to automatically recognize high-level, complex events is a challenging task. Motivated by pre-existing methods being complex, computationally demanding, and often non-replicable, we designed a simple system that is quick, effective and carries minimal overhead in terms of memory and storage. Our system is clearly described, modular in nature, replicable on any Desktop, and demonstrated with extensive experiments, backed by insightful analysis on different Convolutional Neural Networks (CNNs), as stand-alone and fused with others. With a large corpus of unconstrained, real-world video data, we examine the usefulness of different CNN models as features extractors for modeling high-level events, i.e., pre-trained CNNs that differ in architectures, training data, and number of outputs. For each CNN, we use 1-fps from all training exemplar to train one-vs-rest SVMs for each event. To represent videos, frame-level features were fused using a variety of techniques. The best being to max-pool between predetermined shot boundaries, then average-pool to form the final video-level descriptor. Through extensive analysis, several insights were found on using pre-trained CNNs as off-the-shelf feature extractors for the task of event detection. Fusing SVMs of different CNNs revealed some interesting facts, finding some combinations to be complimentary. It was concluded that no single CNN works best for all events, as some events are more object-driven while others are more scene-based. Our top performance resulted from learning event-dependent weights for different CNNs.

Using alcohol intoxication goggles (Fatal Vision® goggles) to detect alcohol related impairment in simulated driving.

PubMed

McCartney, Danielle; Desbrow, Ben; Irwin, Christopher

2017-01-02

Fatal vision goggles (FVGs) are image-distorting equipment used within driver education programs to simulate alcohol-related impairment. However, there is no empirical evidence comparing the behavioral effects associated with wearing FVGs to alcohol intoxication. The purpose of this study was to determine the validity of FVGs in producing alcohol-related impairment in simulated driving. Twenty-two healthy males (age: 23 ± 3 years, mean ± SD) participated in a placebo-controlled crossover design study involving 4 experimental trials. In each trial, participants completed a baseline level simulated driving task followed by an experimental driving task, involving one of 4 treatments: (1) a dose of alcohol designed to elicit 0.080% breath alcohol concentration (BrAC; AB), (2) an alcohol placebo beverage (PB), (3) FVG (estimated % blood alcohol concentration [BAC] 0.070-0.100+), and (4) placebo goggles (PGs). The driving tasks included 3 separate scenarios lasting ∼5 min each; these were a simple driving scenario, a complex driving scenario, and a hazard perception driving scenario. Selected lateral control parameters (standard deviation of lane position [SDLP]; total number of lane crossings [LCs]) and longitudinal control parameters (average speed; standard deviation of speed [SDSP]; distance headway; minimum distance headway) were monitored during the simple and complex driving scenarios. Latency to 2 different stimuli (choice reaction time [CRT]) was tested in the hazard perception driving scenario. Subjective ratings of mood and attitudes toward driving were also provided during each of the trials. Neither placebo treatment influenced simulated driving performance. Mean BrAC was 0.060 ± 0.010% at the time of driving on the AB trial. Lateral control: In the simple driving scenario, SDLP and LC were not affected under any of the experimental treatments. However, in the complex driving scenario, significantly greater SDLP was observed on both the FVG and AB trials compared to their respective baseline drives. LC increased significantly from baseline on the AB trial only. Longitudinal control: Speed was not affected by any of the experimental treatments; however, SDSP increased significantly from baseline on the FVG trial. A significant reduction in distance headway and minimum distance headway was detected on the FVG trial compared to baseline. Hazard perception: Neither AB nor FVG trials were influential on CRT. Subjective mood ratings were significantly altered on the AB and FVG trials compared to baseline and placebo conditions. Participants reported reduced willingness and ability to drive under the active treatments (AB and FVG) than the placebo treatments (PB and PG). FVGs may have some utility in replicating alcohol-related impairment on specific driving performance measurements. Hence, the equipment may offer an alternative approach to researching the impact of alcohol intoxication on simulated driving performance among populations where the provision of alcohol would otherwise be unethical (e.g., prelicensed drivers).

Functional Neuroanatomy Involved in Automatic order Mental Arithmetic and Recitation of the Multiplication Table

NASA Astrophysics Data System (ADS)

Wang, Li-Qun; Saito, Masao

We used 1.5T functional magnetic resonance imaging (fMRI) to explore that which brain areas contribute uniquely to numeric computation. The BOLD effect activation pattern of metal arithmetic task (successive subtraction: actual calculation task) was compared with multiplication tables repetition task (rote verbal arithmetic memory task) response. The activation found in right parietal lobule during metal arithmetic task suggested that quantitative cognition or numeric computation may need the assistance of sensuous convert, such as spatial imagination and spatial sensuous convert. In addition, this mechanism may be an ’analog algorithm’ in the simple mental arithmetic processing.

Individual differences in event-based prospective memory: Evidence for multiple processes supporting cue detection.

PubMed

Brewer, Gene A; Knight, Justin B; Marsh, Richard L; Unsworth, Nash

2010-04-01

The multiprocess view proposes that different processes can be used to detect event-based prospective memory cues, depending in part on the specificity of the cue. According to this theory, attentional processes are not necessary to detect focal cues, whereas detection of nonfocal cues requires some form of controlled attention. This notion was tested using a design in which we compared performance on a focal and on a nonfocal prospective memory task by participants with high or low working memory capacity. An interaction was found, such that participants with high and low working memory performed equally well on the focal task, whereas the participants with high working memory performed significantly better on the nonfocal task than did their counterparts with low working memory. Thus, controlled attention was only necessary for detecting event-based prospective memory cues in the nonfocal task. These results have implications for theories of prospective memory, the processes necessary for cue detection, and the successful fulfillment of intentions.

Narrative Abilities, Memory and Attention in Children with a Specific Language Impairment

ERIC Educational Resources Information Center

Duinmeijer, Iris; de Jong, Jan; Scheper, Annette

2012-01-01

Background: While narrative tasks have proven to be valid measures for detecting language disorders, measuring communicative skills and predicting future academic performance, research into the comparability of different narrative tasks has shown that outcomes are dependent on the type of task used. Although many of the studies detecting task…

Formalized Conflicts Detection Based on the Analysis of Multiple Emails: An Approach Combining Statistics and Ontologies

NASA Astrophysics Data System (ADS)

Zakaria, Chahnez; Curé, Olivier; Salzano, Gabriella; Smaïli, Kamel

In Computer Supported Cooperative Work (CSCW), it is crucial for project leaders to detect conflicting situations as early as possible. Generally, this task is performed manually by studying a set of documents exchanged between team members. In this paper, we propose a full-fledged automatic solution that identifies documents, subjects and actors involved in relational conflicts. Our approach detects conflicts in emails, probably the most popular type of documents in CSCW, but the methods used can handle other text-based documents. These methods rely on the combination of statistical and ontological operations. The proposed solution is decomposed in several steps: (i) we enrich a simple negative emotion ontology with terms occuring in the corpus of emails, (ii) we categorize each conflicting email according to the concepts of this ontology and (iii) we identify emails, subjects and team members involved in conflicting emails using possibilistic description logic and a set of proposed measures. Each of these steps are evaluated and validated on concrete examples. Moreover, this approach's framework is generic and can be easily adapted to domains other than conflicts, e.g. security issues, and extended with operations making use of our proposed set of measures.

Model-Based Fault Tolerant Control

NASA Technical Reports Server (NTRS)

Kumar, Aditya; Viassolo, Daniel

2008-01-01

The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

Leveraging a Sorting Task as a Measure of Knowledge Structure in Bilingual Settings

ERIC Educational Resources Information Center

Tang, Hengtao; Clariana, Roy

2017-01-01

This descriptive exploratory study considers whether a simple sorting task can elicit readers' knowledge structure in learners' first and second language. In this investigation, knowledge structure is considered from a symbolic connectionist viewpoint as the fundamental pre-meaningful aspect of knowledge, where structure is the precursor of…

Differential Distraction Effects in Short-Term and Long-Term Retention of Pictures and Words

ERIC Educational Resources Information Center

Pellegrino, James W.; And Others

1976-01-01

Comparisons between recall levels following simple acoustic or visual tasks and the simultaneous visual-plus-acoustic task are not based upon equivalent amounts of interference within each modality. This research attempts to test more precisely the relationship between visual and acoustic interference by using a sequential rather than a…

It Takes Two: Contrasting Tasks and Contrasting Structures.

ERIC Educational Resources Information Center

Eisenstein, Miriam; And Others

1982-01-01

Examines and compares two measures of adult second language learner performance: cued production and elicited imitation. Discusses the utility of each in terms of the contrasting results of the tasks on a carefully delineated area of grammar, namely the related structure of third person simple present and present progressive in WH-questions. (EKN)

The Value of Emoticons in Investigating Student Emotions Related to Mathematics Task Negotiation

ERIC Educational Resources Information Center

D'Agostin, Fabio

2014-01-01

"Emoticons" are simple face icons expressing common feelings such as happiness, interest and boredom and are popularly used in electronic communication. Emoticons were utilised in this study as experience sampling devices. Year 10 students selected emoticons to indicate their emotional states at set intervals during classroom tasks.…

Children's Verbal Working Memory: Role of Processing Complexity in Predicting Spoken Sentence Comprehension

ERIC Educational Resources Information Center

Magimairaj, Beula M.; Montgomery, James W.

2012-01-01

Purpose: This study investigated the role of processing complexity of verbal working memory tasks in predicting spoken sentence comprehension in typically developing children. Of interest was whether simple and more complex working memory tasks have similar or different power in predicting sentence comprehension. Method: Sixty-five children (6- to…

Neurophysiology and Neuroanatomy of Reflexive and Voluntary Saccades in Non-Human Primates

ERIC Educational Resources Information Center

Johnston, Kevin; Everling, Stefan

2008-01-01

A multitude of cognitive functions can easily be tested by a number of relatively simple saccadic eye movement tasks. This approach has been employed extensively with patient populations to investigate the functional deficits associated with psychiatric disorders. Neurophysiological studies in non-human primates performing the same tasks have…

Laterality and Directional Preferences in Preschool Children.

ERIC Educational Resources Information Center

Tan, Lesley E.

1982-01-01

Directional preference for horizontal hand movements was investigated in 49 right- and 49 left-handed four-year-olds using three drawing tests. Directionality for more complex perceptual-motor tasks has a different basis than directionality for simple tasks; such directionality is established at a later age but only for the right hand. (Author/CM)

Increasing and Decreasing Intrinsic Interest with Contingent Rewards: A Test of Cognitive Evaluation Theory.

ERIC Educational Resources Information Center

Enzle, Michael E.; Ross, June M.

1978-01-01

University students worked puzzles and were given a high or low value cash award, contingent on simple task completion or on attainment of a performance level, or noncontingent and unexpected. Interest in the task after reward was analyzed. Results provided substantial support for Deci's cognitive evaluation theory. (Author/SJL)

Behavioral Measurement of Remembering Phenomenologies: So Simple a Child Can Do It

ERIC Educational Resources Information Center

Brainerd, C. J.; Holliday, R. E.; Reyna, V. F.

2004-01-01

Two remembering phenomenologies, vivid recollection and vague familiarity, have been extensively studied in adults using introspective self-report tasks, such as rememberknow. Because such tasks are beyond the capabilities of young children, there is no database on how these phenomenologies first develop and what factors affect them. In…

The Role of Training, Individual Differences and Knowledge Representation in Cognitive-Oriented Task Performance.

ERIC Educational Resources Information Center

Koubek, Richard J.

The roles of training, problem representation, and individual differences on performance of both automated (simple) and controlled (complex) process tasks were studied. The following hypotheses were tested: (1) training and cognitive style affect the representation developed; (2) training and cognitive style affect the development and performance…

Temporal-contextual processing in working memory: evidence from delayed cued recall and delayed free recall tests.

PubMed

Loaiza, Vanessa M; McCabe, David P

2012-02-01

Three experiments are reported that addressed the nature of processing in working memory by investigating patterns of delayed cued recall and free recall of items initially studied during complex and simple span tasks. In Experiment 1, items initially studied during a complex span task (i.e., operation span) were more likely to be recalled after a delay in response to temporal-contextual cues, relative to items from subspan and supraspan list lengths in a simple span task (i.e., word span). In Experiment 2, items initially studied during operation span were more likely to be recalled from neighboring serial positions during delayed free recall than were items studied during word span trials. Experiment 3 demonstrated that the number of attentional refreshing opportunities strongly predicts episodic memory performance, regardless of whether the information is presented in a spaced or massed format in a modified operation span task. The results indicate that the content-context bindings created during complex span trials reflect attentional refreshing opportunities that are used to maintain items in working memory.

The influence of professional expertise and task complexity upon the potency of the contextual interference effect.

PubMed

Ollis, Stewart; Button, Chris; Fairweather, Malcolm

2005-03-01

The contextual interference (CI) effect has been investigated through practice schedule manipulations within both basic and applied studies. Despite extensive research activity there is little conclusive evidence regarding the optimal practice structure of real world manipulative tasks in professional training settings. The present study therefore assessed the efficacy of practising simple and complex knot-tying skills in professional fire-fighters training. Forty-eight participants were quasi-randomly assigned to various practice schedules along the CI continuum. Twenty-four participants were students selected for their novice knot-tying capabilities and 24 were experienced fire-fighters who were more 'experienced knot-tiers'. They were assessed for skill acquisition, retention and transfer effects having practiced tying knots classified as simple or complex. Surprisingly, high levels of CI scheduling enhance learning for novices even when practising a complex task. The findings also revealed that CI benefits are most apparent as learners engage in tasks high in transfer distality. In conclusion, complexity and experience are mediating factors influencing the potency of the CI training effect in real-world settings.

Stimulus novelty, task relevance and the visual evoked potential in man

NASA Technical Reports Server (NTRS)

Courchesne, E.; Hillyard, S. A.; Galambos, R.

1975-01-01

The effect of task relevance on P3 (waveform of human evoked potential) waves and the methodologies used to deal with them are outlined. Visual evoked potentials (VEPs) were recorded from normal adult subjects performing in a visual discrimination task. Subjects counted the number of presentations of the numeral 4 which was interposed rarely and randomly within a sequence of tachistoscopically flashed background stimuli. Intrusive, task-irrelevant (not counted) stimuli were also interspersed rarely and randomly in the sequence of 2s; these stimuli were of two types: simples, which were easily recognizable, and novels, which were completely unrecognizable. It was found that the simples and the counted 4s evoked posteriorly distributed P3 waves while the irrelevant novels evoked large, frontally distributed P3 waves. These large, frontal P3 waves to novels were also found to be preceded by large N2 waves. These findings indicate that the P3 wave is not a unitary phenomenon but should be considered in terms of a family of waves, differing in their brain generators and in their psychological correlates.

Keep it simple - A case study of model development in the context of the Dynamic Stocks and Flows (DSF) task

NASA Astrophysics Data System (ADS)

Halbrügge, Marc

2010-12-01

This paper describes the creation of a cognitive model submitted to the ‘Dynamic Stocks and Flows’ (DSF) modeling challenge. This challenge aims at comparing computational cognitive models for human behavior during an open ended control task. Participants in the modeling competition were provided with a simulation environment and training data for benchmarking their models while the actual specification of the competition task was withheld. To meet this challenge, the cognitive model described here was designed and optimized for generalizability. Only two simple assumptions about human problem solving were used to explain the empirical findings of the training data. In-depth analysis of the data set prior to the development of the model led to the dismissal of correlations or other parametric statistics as goodness-of-fit indicators. A new statistical measurement based on rank orders and sequence matching techniques is being proposed instead. This measurement, when being applied to the human sample, also identifies clusters of subjects that use different strategies for the task. The acceptability of the fits achieved by the model is verified using permutation tests.

Test of a potential link between analytic and nonanalytic category learning and automatic, effortful processing.

PubMed

Tracy, J I; Pinsk, M; Helverson, J; Urban, G; Dietz, T; Smith, D J

2001-08-01

The link between automatic and effortful processing and nonanalytic and analytic category learning was evaluated in a sample of 29 college undergraduates using declarative memory, semantic category search, and pseudoword categorization tasks. Automatic and effortful processing measures were hypothesized to be associated with nonanalytic and analytic categorization, respectively. Results suggested that contrary to prediction strong criterion-attribute (analytic) responding on the pseudoword categorization task was associated with strong automatic, implicit memory encoding of frequency-of-occurrence information. Data are discussed in terms of the possibility that criterion-attribute category knowledge, once established, may be expressed with few attentional resources. The data indicate that attention resource requirements, even for the same stimuli and task, vary depending on the category rule system utilized. Also, the automaticity emerging from familiarity with analytic category exemplars is very different from the automaticity arising from extensive practice on a semantic category search task. The data do not support any simple mapping of analytic and nonanalytic forms of category learning onto the automatic and effortful processing dichotomy and challenge simple models of brain asymmetries for such procedures. Copyright 2001 Academic Press.

Modelling the dependence of contrast sensitivity on grating area and spatial frequency.

PubMed

Rovamo, J; Luntinen, O; Näsänen, R

1993-12-01

We modelled the human foveal visual system in a detection task as a simple image processor comprising (i) low-pass filtering due to the optical transfer function of the eye, (ii) high-pass filtering of neural origin, (iii) addition of internal neural noise, and (iv) detection by a local matched filter. Its detection efficiency for gratings was constant up to a critical area but then decreased with increasing area. To test the model we measured Michelson contrast sensitivity as a function of grating area at spatial frequencies of 0.125-32 c/deg for simple vertical and circular cosine gratings. In circular gratings luminance was sinusoidally modulated as a function of the radius of the grating field. In agreement with the model, contrast sensitivity at all spatial frequencies increased in proportion to the square-root of grating area at small areas. When grating area exceeded critical area, the increase saturated and contrast sensitivity became independent of area at large grating areas. Spatial integration thus obeyed Piper's law at small grating areas. The critical area of spatial integration, marking the cessation of Piper's law, was constant in solid degrees at low spatial frequencies but inversely proportional to spatial frequency squared at medium and high spatial frequencies. At low spatial frequencies the maximum contrast sensitivity obtainable by spatial integration increased in proportion to spatial frequency but at high spatial frequencies it decreased in proportion to the cube of the increasing spatial frequency. The increase was due to high-pass filtering of neural origin (lateral inhibition) and the decrease was mainly due to the optical transfer function of the eye. Our model explained 95% of the total variance of the contrast sensitivity data.

An interactive driving simulation for driver control and decision-making research

NASA Technical Reports Server (NTRS)

Allen, R. W.; Hogge, J. R.; Schwartz, S. H.

1975-01-01

Display techniques and equations of motion for a relatively simple fixed base car simulation are described. The vehicle dynamics include simplified lateral (steering) and longitudinal (speed) degrees of freedom. Several simulator tasks are described which require a combination of operator control and decision making, including response to wind gust inputs, curved roads, traffic signal lights, and obstacles. Logic circuits are used to detect speeding, running red lights, and crashes. A variety of visual and auditory cues are used to give the driver appropriate performance feedback. The simulated equations of motion are reviewed and the technique for generating the line drawing CRT roadway display is discussed. On-line measurement capabilities and experimenter control features are presented, along with previous and current research results demonstrating simulation capabilities and applications.

Comparing Motor Skills in Autism Spectrum Individuals With and Without Speech Delay

PubMed Central

Barbeau, Elise B.; Meilleur, Andrée‐Anne S.; Zeffiro, Thomas A.

2015-01-01

Movement atypicalities in speed, coordination, posture, and gait have been observed across the autism spectrum (AS) and atypicalities in coordination are more commonly observed in AS individuals without delayed speech (DSM‐IV Asperger) than in those with atypical or delayed speech onset. However, few studies have provided quantitative data to support these mostly clinical observations. Here, we compared perceptual and motor performance between 30 typically developing and AS individuals (21 with speech delay and 18 without speech delay) to examine the associations between limb movement control and atypical speech development. Groups were matched for age, intelligence, and sex. The experimental design included: an inspection time task, which measures visual processing speed; the Purdue Pegboard, which measures finger dexterity, bimanual performance, and hand‐eye coordination; the Annett Peg Moving Task, which measures unimanual goal‐directed arm movement; and a simple reaction time task. We used analysis of covariance to investigate group differences in task performance and linear regression models to explore potential associations between intelligence, language skills, simple reaction time, and visually guided movement performance. AS participants without speech delay performed slower than typical participants in the Purdue Pegboard subtests. AS participants without speech delay showed poorer bimanual coordination than those with speech delay. Visual processing speed was slightly faster in both AS groups than in the typical group. Altogether, these results suggest that AS individuals with and without speech delay differ in visually guided and visually triggered behavior and show that early language skills are associated with slower movement in simple and complex motor tasks. Autism Res 2015, 8: 682–693. © 2015 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research PMID:25820662

The role of optimality in characterizing CO2 seepage from geological carbon sequestration sites

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

Cortis, Andrea; Oldenburg, Curtis M.; Benson, Sally M.

Storage of large amounts of carbon dioxide (CO{sub 2}) in deep geological formations for greenhouse gas mitigation is gaining momentum and moving from its conceptual and testing stages towards widespread application. In this work we explore various optimization strategies for characterizing surface leakage (seepage) using near-surface measurement approaches such as accumulation chambers and eddy covariance towers. Seepage characterization objectives and limitations need to be defined carefully from the outset especially in light of large natural background variations that can mask seepage. The cost and sensitivity of seepage detection are related to four critical length scales pertaining to the size ofmore » the: (1) region that needs to be monitored; (2) footprint of the measurement approach, and (3) main seepage zone; and (4) region in which concentrations or fluxes are influenced by seepage. Seepage characterization objectives may include one or all of the tasks of detecting, locating, and quantifying seepage. Each of these tasks has its own optimal strategy. Detecting and locating seepage in a region in which there is no expected or preferred location for seepage nor existing evidence for seepage requires monitoring on a fixed grid, e.g., using eddy covariance towers. The fixed-grid approaches needed to detect seepage are expected to require large numbers of eddy covariance towers for large-scale geologic CO{sub 2} storage. Once seepage has been detected and roughly located, seepage zones and features can be optimally pinpointed through a dynamic search strategy, e.g., employing accumulation chambers and/or soil-gas sampling. Quantification of seepage rates can be done through measurements on a localized fixed grid once the seepage is pinpointed. Background measurements are essential for seepage detection in natural ecosystems. Artificial neural networks are considered as regression models useful for distinguishing natural system behavior from anomalous behavior suggestive of CO{sub 2} seepage without need for detailed understanding of natural system processes. Because of the local extrema in CO{sub 2} fluxes and concentrations in natural systems, simple steepest-descent algorithms are not effective and evolutionary computation algorithms are proposed as a paradigm for dynamic monitoring networks to pinpoint CO{sub 2} seepage areas.« less

Automated high-grade prostate cancer detection and ranking on whole slide images

NASA Astrophysics Data System (ADS)

Huang, Chao-Hui; Racoceanu, Daniel

2017-03-01

Recently, digital pathology (DP) has been largely improved due to the development of computer vision and machine learning. Automated detection of high-grade prostate carcinoma (HG-PCa) is an impactful medical use-case showing the paradigm of collaboration between DP and computer science: given a field of view (FOV) from a whole slide image (WSI), the computer-aided system is able to determine the grade by classifying the FOV. Various approaches have been reported based on this approach. However, there are two reasons supporting us to conduct this work: first, there is still room for improvement in terms of detection accuracy of HG-PCa; second, a clinical practice is more complex than the operation of simple image classification. FOV ranking is also an essential step. E.g., in clinical practice, a pathologist usually evaluates a case based on a few FOVs from the given WSI. Then, makes decision based on the most severe FOV. This important ranking scenario is not yet being well discussed. In this work, we introduce an automated detection and ranking system for PCa based on Gleason pattern discrimination. Our experiments suggested that the proposed system is able to perform high-accuracy detection ( 95:57% +/- 2:1%) and excellent performance of ranking. Hence, the proposed system has a great potential to support the daily tasks in the medical routine of clinical pathology.

Flexibility in data interpretation: effects of representational format.

PubMed

Braithwaite, David W; Goldstone, Robert L

2013-01-01

Graphs and tables differentially support performance on specific tasks. For tasks requiring reading off single data points, tables are as good as or better than graphs, while for tasks involving relationships among data points, graphs often yield better performance. However, the degree to which graphs and tables support flexibility across a range of tasks is not well-understood. In two experiments, participants detected main and interaction effects in line graphs and tables of bivariate data. Graphs led to more efficient performance, but also lower flexibility, as indicated by a larger discrepancy in performance across tasks. In particular, detection of main effects of variables represented in the graph legend was facilitated relative to detection of main effects of variables represented in the x-axis. Graphs may be a preferable representational format when the desired task or analytical perspective is known in advance, but may also induce greater interpretive bias than tables, necessitating greater care in their use and design.

BEHAVIORAL PHARMACOLOGY OF THE ODOR SPAN TASK: EFFECTS OF FLUNITRAZEPAM, KETAMINE, METHAMPHETAMINE AND METHYLPHENIDATE

PubMed Central

Galizio, Mark; April, Brooke; Deal, Melissa; Hawkey, Andrew; Panoz-Brown, Danielle; Prichard, Ashley; Bruce, Katherine

2018-01-01

The Odor Span Task is an incrementing non-matching-to-sample procedure that permits the study of behavior under the control of multiple stimuli. Rats are exposed to a series of odor stimuli and selection of new stimuli is reinforced. Successful performance thus requires remembering which stimuli have previously been presented during a given session. This procedure has been frequently used in neurobiological studies as a rodent model of working memory; however, only a few studies have examined the effects of drugs on performance in this task. The present experiments explored the behavioral pharmacology of a modified version of the Odor Span Task by determining the effects of stimulant drugs methylphenidate and methamphetamine, NMDA antagonist ketamine, and positive GABAA modulator flunitrazepam. All four drugs produced dose-dependent impairment of performances on the Odor Span Task, but for methylphenidate and methamphetamine, these occurred only at doses that had similar effects on performance of a simple odor discrimination. Generally, these disruptions were based on omission of responding at the effective doses. The effects of ketamine and flunitrazepam were more selective in some rats. That is, some rats tested under flunitrazepam and ketamine showed decreases in accuracy on the Odor Span Task at doses that did not affect simple discrimination performance. These selective effects indicate disruption of within-session stimulus control. Overall, these findings support the potential of the Odor Span Task as a baseline for the behavioral pharmacological analysis of remembering. PMID:27747877

Relations between Short-term Memory Deficits, Semantic Processing, and Executive Function

PubMed Central

Allen, Corinne M.; Martin, Randi C.; Martin, Nadine

2012-01-01

Background Previous research has suggested separable short-term memory (STM) buffers for the maintenance of phonological and lexical-semantic information, as some patients with aphasia show better ability to retain semantic than phonological information and others show the reverse. Recently, researchers have proposed that deficits to the maintenance of semantic information in STM are related to executive control abilities. Aims The present study investigated the relationship of executive function abilities with semantic and phonological short-term memory (STM) and semantic processing in such patients, as some previous research has suggested that semantic STM deficits and semantic processing abilities are critically related to specific or general executive function deficits. Method and Procedures 20 patients with aphasia and STM deficits were tested on measures of short-term retention, semantic processing, and both complex and simple executive function tasks. Outcome and Results In correlational analyses, we found no relation between semantic STM and performance on simple or complex executive function tasks. In contrast, phonological STM was related to executive function performance in tasks that had a verbal component, suggesting that performance in some executive function tasks depends on maintaining or rehearsing phonological codes. Although semantic STM was not related to executive function ability, performance on semantic processing tasks was related to executive function, perhaps due to similar executive task requirements in both semantic processing and executive function tasks. Conclusions Implications for treatment and interpretations of executive deficits are discussed. PMID:22736889

Nonlinear analysis of saccade speed fluctuations during combined action and perception tasks

PubMed Central

Stan, C.; Astefanoaei, C.; Pretegiani, E.; Optican, L.; Creanga, D.; Rufa, A.; Cristescu, C.P.

2014-01-01

Background: Saccades are rapid eye movements used to gather information about a scene which requires both action and perception. These are usually studied separately, so that how perception influences action is not well understood. In a dual task, where the subject looks at a target and reports a decision, subtle changes in the saccades might be caused by action-perception interactions. Studying saccades might provide insight into how brain pathways for action and for perception interact. New method: We applied two complementary methods, multifractal detrended fluctuation analysis and Lempel-Ziv complexity index to eye peak speed recorded in two experiments, a pure action task and a combined action-perception task. Results: Multifractality strength is significantly different in the two experiments, showing smaller values for dual decision task saccades compared to simple-task saccades. The normalized Lempel-Ziv complexity index behaves similarly i.e. is significantly smaller in the decision saccade task than in the simple task. Comparison with existing methods: Compared to the usual statistical and linear approaches, these analyses emphasize the character of the dynamics involved in the fluctuations and offer a sensitive tool for quantitative evaluation of the multifractal features and of the complexity measure in the saccades peak speeds when different brain circuits are involved. Conclusion: Our results prove that the peak speed fluctuations have multifractal characteristics with lower magnitude for the multifractality strength and for the complexity index when two neural pathways are simultaneously activated, demonstrating the nonlinear interaction in the brain pathways for action and perception. PMID:24854830

Motor demands impact speed of information processing in Autism Spectrum Disorders

PubMed Central

Kenworthy, Lauren; Yerys, Benjamin E.; Weinblatt, Rachel; Abrams, Danielle N.; Wallace, Gregory L.

2015-01-01

Objective The apparent contradiction between preserved or even enhanced perceptual processing speed on inspection time tasks in autism spectrum disorders (ASD) and impaired performance on complex processing speed tasks that require motor output (e.g. Wechsler Processing Speed Index) has not yet been systematically investigated. This study investigates whether adding motor output demands to an inspection time task impairs ASD performance compared to that of typically developing control (TDC) children. Method The performance of children with ASD (n=28; mean FSIQ=115) and TDC (n=25; mean FSIQ=122) children was compared on processing speed tasks with increasing motor demand. Correlations were run between ASD task performance and Autism Diagnostic Observation Schedule (ADOS) Communication scores. Results Performance by the ASD and TDC groups on a simple perceptual processing speed task with minimal motor demand was equivalent, though it diverged (ASD worse than TDC) on two tasks with the same stimuli, but increased motor output demands. ASD performance on the moderate but not the high speeded motor output demand task was negatively correlated with ADOS communication symptoms. Conclusions These data address the apparent contradiction between preserved inspection time in the context of slowed “processing speed” in ASD. They show that processing speed is preserved when motor demands are minimized, but that increased motor output demands interfere with the ability to act on perceptual processing of simple stimuli. Reducing motor demands (e.g. through the use of computers) may increase the capacity of people with ASD to demonstrate good perceptual processing in a variety of educational, vocational and social settings. PMID:23937483

Lesions of the rat nucleus basalis magnocellularis disrupt appetitive-to-aversive transfer learning.

PubMed

Butt, A E; Schultz, J A; Arnold, L L; Garman, E E; George, C L; Garraghty, P E

2003-01-01

Rats with selective lesions of the nucleus basalis magnocellularis (NBM) and sham-lesion control animals were tested in an operant appetitive-to-aversive transfer task. We hypothesized that NBM lesions would not affect performance in the appetitive phase, but that performance would be impaired during subsequent transfer to the aversive phase of the task. Additional groups of NBM lesion and control rats were tested in the avoidance condition only, where we hypothesized that NBM lesions would not disrupt performance. These hypotheses were based on the argument that the NBM is not necessary for simple association learning that does not tax attention. Both the appetitive phase of the transfer task and the avoidance only task depend only on simple associative learning and are argued not to tax attention. Consequently, performance in these tasks was predicted to be spared following NBM lesions. Complex, attention-demanding associative learning, however, is argued to depend on the NBM. Performance in the aversive phase of the transfer task is both attentionally demanding and associatively more complex than in either the appetitive or aversive tasks alone; thus, avoidance performance in the NBM lesion group was predicted to be impaired following transfer from prior appetitive conditioning. Results supported our hypotheses, with the NBM lesion group acquiring the appetitive response normally, but showing impaired performance following transfer to the aversive conditioning phase of the transfer task. Impairments were not attributable to disrupted avoidance learning per se, as avoidance behavior was normal in the NBM lesion group tested in the avoidance condition only.

Breakdown of Spatial Parallel Coding in Children's Drawing

ERIC Educational Resources Information Center

De Bruyn, Bart; Davis, Alyson

2005-01-01

When drawing real scenes or copying simple geometric figures young children are highly sensitive to parallel cues and use them effectively. However, this sensitivity can break down in surprisingly simple tasks such as copying a single line where robust directional errors occur despite the presence of parallel cues. Before we can conclude that this…

Social Network Analysis: A Simple but Powerful Tool for Identifying Teacher Leaders

ERIC Educational Resources Information Center

Smith, P. Sean; Trygstad, Peggy J.; Hayes, Meredith L.

2018-01-01

Instructional teacher leadership is central to a vision of distributed leadership. However, identifying instructional teacher leaders can be a daunting task, particularly for administrators who find themselves either newly appointed or faced with high staff turnover. This article describes the use of social network analysis (SNA), a simple but…

Incremental Sentence Processing in Japanese: A Maze Investigation into Scrambled and Control Sentences

ERIC Educational Resources Information Center

Witzel, Jeffrey; Witzel, Naoko

2016-01-01

This study investigates preverbal structural and semantic processing in Japanese, a head-final language, using the maze task. Two sentence types were tested--simple scrambled sentences (Experiment 1) and control sentences (Experiment 2). Experiment 1 showed that even for simple, mono-clausal Japanese sentences, (1) there are online processing…

Distinguishing bias from sensitivity effects in multialternative detection tasks.

PubMed

Sridharan, Devarajan; Steinmetz, Nicholas A; Moore, Tirin; Knudsen, Eric I

2014-08-21

Studies investigating the neural bases of cognitive phenomena increasingly employ multialternative detection tasks that seek to measure the ability to detect a target stimulus or changes in some target feature (e.g., orientation or direction of motion) that could occur at one of many locations. In such tasks, it is essential to distinguish the behavioral and neural correlates of enhanced perceptual sensitivity from those of increased bias for a particular location or choice (choice bias). However, making such a distinction is not possible with established approaches. We present a new signal detection model that decouples the behavioral effects of choice bias from those of perceptual sensitivity in multialternative (change) detection tasks. By formulating the perceptual decision in a multidimensional decision space, our model quantifies the respective contributions of bias and sensitivity to multialternative behavioral choices. With a combination of analytical and numerical approaches, we demonstrate an optimal, one-to-one mapping between model parameters and choice probabilities even for tasks involving arbitrarily large numbers of alternatives. We validated the model with published data from two ternary choice experiments: a target-detection experiment and a length-discrimination experiment. The results of this validation provided novel insights into perceptual processes (sensory noise and competitive interactions) that can accurately and parsimoniously account for observers' behavior in each task. The model will find important application in identifying and interpreting the effects of behavioral manipulations (e.g., cueing attention) or neural perturbations (e.g., stimulation or inactivation) in a variety of multialternative tasks of perception, attention, and decision-making. © 2014 ARVO.

Distinguishing bias from sensitivity effects in multialternative detection tasks

PubMed Central

Sridharan, Devarajan; Steinmetz, Nicholas A.; Moore, Tirin; Knudsen, Eric I.

2014-01-01

Studies investigating the neural bases of cognitive phenomena increasingly employ multialternative detection tasks that seek to measure the ability to detect a target stimulus or changes in some target feature (e.g., orientation or direction of motion) that could occur at one of many locations. In such tasks, it is essential to distinguish the behavioral and neural correlates of enhanced perceptual sensitivity from those of increased bias for a particular location or choice (choice bias). However, making such a distinction is not possible with established approaches. We present a new signal detection model that decouples the behavioral effects of choice bias from those of perceptual sensitivity in multialternative (change) detection tasks. By formulating the perceptual decision in a multidimensional decision space, our model quantifies the respective contributions of bias and sensitivity to multialternative behavioral choices. With a combination of analytical and numerical approaches, we demonstrate an optimal, one-to-one mapping between model parameters and choice probabilities even for tasks involving arbitrarily large numbers of alternatives. We validated the model with published data from two ternary choice experiments: a target-detection experiment and a length-discrimination experiment. The results of this validation provided novel insights into perceptual processes (sensory noise and competitive interactions) that can accurately and parsimoniously account for observers' behavior in each task. The model will find important application in identifying and interpreting the effects of behavioral manipulations (e.g., cueing attention) or neural perturbations (e.g., stimulation or inactivation) in a variety of multialternative tasks of perception, attention, and decision-making. PMID:25146574

Time course based artifact identification for independent components of resting-state FMRI.

PubMed

Rummel, Christian; Verma, Rajeev Kumar; Schöpf, Veronika; Abela, Eugenio; Hauf, Martinus; Berruecos, José Fernando Zapata; Wiest, Roland

2013-01-01

In functional magnetic resonance imaging (fMRI) coherent oscillations of the blood oxygen level-dependent (BOLD) signal can be detected. These arise when brain regions respond to external stimuli or are activated by tasks. The same networks have been characterized during wakeful rest when functional connectivity of the human brain is organized in generic resting-state networks (RSN). Alterations of RSN emerge as neurobiological markers of pathological conditions such as altered mental state. In single-subject fMRI data the coherent components can be identified by blind source separation of the pre-processed BOLD data using spatial independent component analysis (ICA) and related approaches. The resulting maps may represent physiological RSNs or may be due to various artifacts. In this methodological study, we propose a conceptually simple and fully automatic time course based filtering procedure to detect obvious artifacts in the ICA output for resting-state fMRI. The filter is trained on six and tested on 29 healthy subjects, yielding mean filter accuracy, sensitivity and specificity of 0.80, 0.82, and 0.75 in out-of-sample tests. To estimate the impact of clearly artifactual single-subject components on group resting-state studies we analyze unfiltered and filtered output with a second level ICA procedure. Although the automated filter does not reach performance values of visual analysis by human raters, we propose that resting-state compatible analysis of ICA time courses could be very useful to complement the existing map or task/event oriented artifact classification algorithms.

A Flexible Question-and-Answer Task for Measuring Speech Understanding.

PubMed

Best, Virginia; Streeter, Timothy; Roverud, Elin; Mason, Christine R; Kidd, Gerald

2016-11-24

This report introduces a new speech task based on simple questions and answers. The task differs from a traditional sentence recall task in that it involves an element of comprehension and can be implemented in an ongoing fashion. It also contains two target items (the question and the answer) that may be associated with different voices and locations to create dynamic listening scenarios. A set of 227 questions was created, covering six broad categories (days of the week, months of the year, numbers, colors, opposites, and sizes). All questions and their one-word answers were spoken by 11 female and 11 male talkers. In this study, listeners were presented with question-answer pairs and asked to indicate whether the answer was true or false. Responses were given as simple button or key presses, which are quick to make and easy to score. Two preliminary experiments are presented that illustrate different ways of implementing the basic task. In the first experiment, question-answer pairs were presented in speech-shaped noise, and performance was compared across subjects, question categories, and time, to examine the different sources of variability. In the second experiment, sequences of question-answer pairs were presented amidst competing conversations in an ongoing, spatially dynamic listening scenario. Overall, the question-and-answer task appears to be feasible and could be implemented flexibly in a number of different ways. © The Author(s) 2016.

A Flexible Question-and-Answer Task for Measuring Speech Understanding

PubMed Central

Streeter, Timothy; Roverud, Elin; Mason, Christine R.; Kidd, Gerald

2016-01-01

This report introduces a new speech task based on simple questions and answers. The task differs from a traditional sentence recall task in that it involves an element of comprehension and can be implemented in an ongoing fashion. It also contains two target items (the question and the answer) that may be associated with different voices and locations to create dynamic listening scenarios. A set of 227 questions was created, covering six broad categories (days of the week, months of the year, numbers, colors, opposites, and sizes). All questions and their one-word answers were spoken by 11 female and 11 male talkers. In this study, listeners were presented with question-answer pairs and asked to indicate whether the answer was true or false. Responses were given as simple button or key presses, which are quick to make and easy to score. Two preliminary experiments are presented that illustrate different ways of implementing the basic task. In the first experiment, question-answer pairs were presented in speech-shaped noise, and performance was compared across subjects, question categories, and time, to examine the different sources of variability. In the second experiment, sequences of question-answer pairs were presented amidst competing conversations in an ongoing, spatially dynamic listening scenario. Overall, the question-and-answer task appears to be feasible and could be implemented flexibly in a number of different ways. PMID:27888257

Protein detection by Simple Western™ analysis.

PubMed

Harris, Valerie M

2015-01-01

Protein Simple© has taken a well-known protein detection method, the western blot, and revolutionized it. The Simple Western™ system uses capillary electrophoresis to identify and quantitate a protein of interest. Protein Simple© provides multiple detection apparatuses (Wes, Sally Sue, or Peggy Sue) that are suggested to save scientists valuable time by allowing the researcher to prepare the protein sample, load it along with necessary antibodies and substrates, and walk away. Within 3-5 h the protein will be separated by size, or charge, immuno-detection of target protein will be accurately quantitated, and results will be immediately made available. Using the Peggy Sue instrument, one study recently examined changes in MAPK signaling proteins in the sex-determining stage of gonadal development. Here the methodology is described.

Behavioral semantics of learning and crossmodal processing in auditory cortex: the semantic processor concept.

PubMed

Scheich, Henning; Brechmann, André; Brosch, Michael; Budinger, Eike; Ohl, Frank W; Selezneva, Elena; Stark, Holger; Tischmeyer, Wolfgang; Wetzel, Wolfram

2011-01-01

Two phenomena of auditory cortex activity have recently attracted attention, namely that the primary field can show different types of learning-related changes of sound representation and that during learning even this early auditory cortex is under strong multimodal influence. Based on neuronal recordings in animal auditory cortex during instrumental tasks, in this review we put forward the hypothesis that these two phenomena serve to derive the task-specific meaning of sounds by associative learning. To understand the implications of this tenet, it is helpful to realize how a behavioral meaning is usually derived for novel environmental sounds. For this purpose, associations with other sensory, e.g. visual, information are mandatory to develop a connection between a sound and its behaviorally relevant cause and/or the context of sound occurrence. This makes it plausible that in instrumental tasks various non-auditory sensory and procedural contingencies of sound generation become co-represented by neuronal firing in auditory cortex. Information related to reward or to avoidance of discomfort during task learning, that is essentially non-auditory, is also co-represented. The reinforcement influence points to the dopaminergic internal reward system, the local role of which for memory consolidation in auditory cortex is well-established. Thus, during a trial of task performance, the neuronal responses to the sounds are embedded in a sequence of representations of such non-auditory information. The embedded auditory responses show task-related modulations of auditory responses falling into types that correspond to three basic logical classifications that may be performed with a perceptual item, i.e. from simple detection to discrimination, and categorization. This hierarchy of classifications determine the semantic "same-different" relationships among sounds. Different cognitive classifications appear to be a consequence of learning task and lead to a recruitment of different excitatory and inhibitory mechanisms and to distinct spatiotemporal metrics of map activation to represent a sound. The described non-auditory firing and modulations of auditory responses suggest that auditory cortex, by collecting all necessary information, functions as a "semantic processor" deducing the task-specific meaning of sounds by learning. © 2010. Published by Elsevier B.V.

Quantifying Human Performance of a Dynamic Military Target Detection Task: An Application of the Theory of Signal Detection.

DTIC Science & Technology

1995-06-01

applied to analyze numerous experimental tasks (Macmillan and Creelman , 1991). One of these tasks, target detection, is the subject research. In...between each associated pair of false alarm rate and hit rate z-scores is d’ for the bias level associated with the pairing (Macmillan and Creelman , 1991...unequal variance in normal distributions (Macmillan and Creelman , 1991). 61 1966). It is described in detail for the interested reader by Green and

Getting a Grip on Social Gaze: Control over Others' Gaze Helps Gaze Detection in High-Functioning Autism

ERIC Educational Resources Information Center

Dratsch, Thomas; Schwartz, Caroline; Yanev, Kliment; Schilbach, Leonhard; Vogeley, Kai; Bente, Gary

2013-01-01

We investigated the influence of control over a social stimulus on the ability to detect direct gaze in high-functioning autism (HFA). In a pilot study, 19 participants with and 19 without HFA were compared on a gaze detection and a gaze setting task. Participants with HFA were less accurate in detecting direct gaze in the detection task, but did…

Impact of Automation Support on the Conflict Resolution Task in a Human-in-the-Loop Air Traffic Control Simulation

NASA Technical Reports Server (NTRS)

Mercer, Joey; Gomez, Ashley; Gabets, Cynthia; Bienert, Nancy; Edwards, Tamsyn; Martin, Lynne; Gujral, Vimmy; Homola, Jeffrey

2016-01-01

To determine the capabilities and limitations of human operators and automation in separation assurance roles, the second of three Human-in-the-Loop (HITL) part-task studies investigated air traffic controllers ability to detect and resolve conflicts under varying task sets, traffic densities, and run lengths. Operations remained within a single sector, staffed by a single controller, and explored, among other things, the controllers responsibility for conflict resolution with or without their involvement in the conflict detection task. Furthermore, these conditions were examined across two different traffic densities; 1x (current-day traffic) and a 20 increase above current-day traffic levels (1.2x). Analyses herein offer an examination of the conflict resolution strategies employed by controllers. In particular, data in the form of elapsed time between conflict detection and conflict resolution are used to assess if, and how, the controllers involvement in the conflict detection task affected the way in which they resolved traffic conflicts.

Image patch-based method for automated classification and detection of focal liver lesions on CT

NASA Astrophysics Data System (ADS)

Safdari, Mustafa; Pasari, Raghav; Rubin, Daniel; Greenspan, Hayit

2013-03-01

We developed a method for automated classification and detection of liver lesions in CT images based on image patch representation and bag-of-visual-words (BoVW). BoVW analysis has been extensively used in the computer vision domain to analyze scenery images. In the current work we discuss how it can be used for liver lesion classification and detection. The methodology includes building a dictionary for a training set using local descriptors and representing a region in the image using a visual word histogram. Two tasks are described: a classification task, for lesion characterization, and a detection task in which a scan window moves across the image and is determined to be normal liver tissue or a lesion. Data: In the classification task 73 CT images of liver lesions were used, 25 images having cysts, 24 having metastasis and 24 having hemangiomas. A radiologist circumscribed the lesions, creating a region of interest (ROI), in each of the images. He then provided the diagnosis, which was established either by biopsy or clinical follow-up. Thus our data set comprises 73 images and 73 ROIs. In the detection task, a radiologist drew ROIs around each liver lesion and two regions of normal liver, for a total of 159 liver lesion ROIs and 146 normal liver ROIs. The radiologist also demarcated the liver boundary. Results: Classification results of more than 95% were obtained. In the detection task, F1 results obtained is 0.76. Recall is 84%, with precision of 73%. Results show the ability to detect lesions, regardless of shape.

Blur Detection is Unaffected by Cognitive Load.

PubMed

Loschky, Lester C; Ringer, Ryan V; Johnson, Aaron P; Larson, Adam M; Neider, Mark; Kramer, Arthur F

2014-03-01

Blur detection is affected by retinal eccentricity, but is it also affected by attentional resources? Research showing effects of selective attention on acuity and contrast sensitivity suggests that allocating attention should increase blur detection. However, research showing that blur affects selection of saccade targets suggests that blur detection may be pre-attentive. To investigate this question, we carried out experiments in which viewers detected blur in real-world scenes under varying levels of cognitive load manipulated by the N -back task. We used adaptive threshold estimation to measure blur detection thresholds at 0°, 3°, 6°, and 9° eccentricity. Participants carried out blur detection as a single task, a single task with to-be-ignored letters, or an N-back task with four levels of cognitive load (0, 1, 2, or 3-back). In Experiment 1, blur was presented gaze-contingently for occasional single eye fixations while participants viewed scenes in preparation for an easy picture recognition memory task, and the N -back stimuli were presented auditorily. The results for three participants showed a large effect of retinal eccentricity on blur thresholds, significant effects of N -back level on N -back performance, scene recognition memory, and gaze dispersion, but no effect of N -back level on blur thresholds. In Experiment 2, we replicated Experiment 1 but presented the images tachistoscopically for 200 ms (half with, half without blur), to determine whether gaze-contingent blur presentation in Experiment 1 had produced attentional capture by blur onset during a fixation, thus eliminating any effect of cognitive load on blur detection. The results with three new participants replicated those of Experiment 1, indicating that the use of gaze-contingent blur presentation could not explain the lack of effect of cognitive load on blur detection. Thus, apparently blur detection in real-world scene images is unaffected by attentional resources, as manipulated by the cognitive load produced by the N -back task.

Goal-Directed Decision Making with Spiking Neurons.

PubMed

Friedrich, Johannes; Lengyel, Máté

2016-02-03

Behavioral and neuroscientific data on reward-based decision making point to a fundamental distinction between habitual and goal-directed action selection. The formation of habits, which requires simple updating of cached values, has been studied in great detail, and the reward prediction error theory of dopamine function has enjoyed prominent success in accounting for its neural bases. In contrast, the neural circuit mechanisms of goal-directed decision making, requiring extended iterative computations to estimate values online, are still unknown. Here we present a spiking neural network that provably solves the difficult online value estimation problem underlying goal-directed decision making in a near-optimal way and reproduces behavioral as well as neurophysiological experimental data on tasks ranging from simple binary choice to sequential decision making. Our model uses local plasticity rules to learn the synaptic weights of a simple neural network to achieve optimal performance and solves one-step decision-making tasks, commonly considered in neuroeconomics, as well as more challenging sequential decision-making tasks within 1 s. These decision times, and their parametric dependence on task parameters, as well as the final choice probabilities match behavioral data, whereas the evolution of neural activities in the network closely mimics neural responses recorded in frontal cortices during the execution of such tasks. Our theory provides a principled framework to understand the neural underpinning of goal-directed decision making and makes novel predictions for sequential decision-making tasks with multiple rewards. Goal-directed actions requiring prospective planning pervade decision making, but their circuit-level mechanisms remain elusive. We show how a model circuit of biologically realistic spiking neurons can solve this computationally challenging problem in a novel way. The synaptic weights of our network can be learned using local plasticity rules such that its dynamics devise a near-optimal plan of action. By systematically comparing our model results to experimental data, we show that it reproduces behavioral decision times and choice probabilities as well as neural responses in a rich set of tasks. Our results thus offer the first biologically realistic account for complex goal-directed decision making at a computational, algorithmic, and implementational level. Copyright © 2016 the authors 0270-6474/16/361529-18$15.00/0.

Goal-Directed Decision Making with Spiking Neurons

PubMed Central

Lengyel, Máté

2016-01-01

Behavioral and neuroscientific data on reward-based decision making point to a fundamental distinction between habitual and goal-directed action selection. The formation of habits, which requires simple updating of cached values, has been studied in great detail, and the reward prediction error theory of dopamine function has enjoyed prominent success in accounting for its neural bases. In contrast, the neural circuit mechanisms of goal-directed decision making, requiring extended iterative computations to estimate values online, are still unknown. Here we present a spiking neural network that provably solves the difficult online value estimation problem underlying goal-directed decision making in a near-optimal way and reproduces behavioral as well as neurophysiological experimental data on tasks ranging from simple binary choice to sequential decision making. Our model uses local plasticity rules to learn the synaptic weights of a simple neural network to achieve optimal performance and solves one-step decision-making tasks, commonly considered in neuroeconomics, as well as more challenging sequential decision-making tasks within 1 s. These decision times, and their parametric dependence on task parameters, as well as the final choice probabilities match behavioral data, whereas the evolution of neural activities in the network closely mimics neural responses recorded in frontal cortices during the execution of such tasks. Our theory provides a principled framework to understand the neural underpinning of goal-directed decision making and makes novel predictions for sequential decision-making tasks with multiple rewards. SIGNIFICANCE STATEMENT Goal-directed actions requiring prospective planning pervade decision making, but their circuit-level mechanisms remain elusive. We show how a model circuit of biologically realistic spiking neurons can solve this computationally challenging problem in a novel way. The synaptic weights of our network can be learned using local plasticity rules such that its dynamics devise a near-optimal plan of action. By systematically comparing our model results to experimental data, we show that it reproduces behavioral decision times and choice probabilities as well as neural responses in a rich set of tasks. Our results thus offer the first biologically realistic account for complex goal-directed decision making at a computational, algorithmic, and implementational level. PMID:26843636

Simple control-theoretic models of human steering activity in visually guided vehicle control

NASA Technical Reports Server (NTRS)

Hess, Ronald A.

1991-01-01

A simple control theoretic model of human steering or control activity in the lateral-directional control of vehicles such as automobiles and rotorcraft is discussed. The term 'control theoretic' is used to emphasize the fact that the model is derived from a consideration of well-known control system design principles as opposed to psychological theories regarding egomotion, etc. The model is employed to emphasize the 'closed-loop' nature of tasks involving the visually guided control of vehicles upon, or in close proximity to, the earth and to hypothesize how changes in vehicle dynamics can significantly alter the nature of the visual cues which a human might use in such tasks.

Inversion Of Jacobian Matrix For Robot Manipulators

NASA Technical Reports Server (NTRS)

Fijany, Amir; Bejczy, Antal K.

1989-01-01

Report discusses inversion of Jacobian matrix for class of six-degree-of-freedom arms with spherical wrist, i.e., with last three joints intersecting. Shows by taking advantage of simple geometry of such arms, closed-form solution of Q=J-1X, which represents linear transformation from task space to joint space, obtained efficiently. Presents solutions for PUMA arm, JPL/Stanford arm, and six-revolute-joint coplanar arm along with all singular points. Main contribution of paper shows simple geometry of this type of arms exploited in performing inverse transformation without any need to compute Jacobian or its inverse explicitly. Implication of this computational efficiency advanced task-space control schemes for spherical-wrist arms implemented more efficiently.

The Impact of Different Environmental Conditions on Cognitive Function: A Focused Review

PubMed Central

Taylor, Lee; Watkins, Samuel L.; Marshall, Hannah; Dascombe, Ben J.; Foster, Josh

2016-01-01

Cognitive function defines performance in objective tasks that require conscious mental effort. Extreme environments, namely heat, hypoxia, and cold can all alter human cognitive function due to a variety of psychological and/or biological processes. The aims of this Focused Review were to discuss; (1) the current state of knowledge on the effects of heat, hypoxic and cold stress on cognitive function, (2) the potential mechanisms underpinning these alterations, and (3) plausible interventions that may maintain cognitive function upon exposure to each of these environmental stressors. The available evidence suggests that the effects of heat, hypoxia, and cold stress on cognitive function are both task and severity dependent. Complex tasks are particularly vulnerable to extreme heat stress, whereas both simple and complex task performance appear to be vulnerable at even at moderate altitudes. Cold stress also appears to negatively impact both simple and complex task performance, however, the research in this area is sparse in comparison to heat and hypoxia. In summary, this focused review provides updated knowledge regarding the effects of extreme environmental stressors on cognitive function and their biological underpinnings. Tyrosine supplementation may help individuals maintain cognitive function in very hot, hypoxic, and/or cold conditions. However, more research is needed to clarify these and other postulated interventions. PMID:26779029

Laterality of Grooming and Tool Use in a Group of Captive Bonobos (Pan paniscus).

PubMed

Brand, Colin M; Marchant, Linda F; Boose, Klaree J; White, Frances J; Rood, Tabatha M; Meinelt, Audra

2017-01-01

Humans exhibit population level handedness for the right hand; however, the evolution of this behavioral phenotype is poorly understood. Here, we compared the laterality of a simple task (grooming) and a complex task (tool use) to investigate whether increasing task difficulty elicited individual hand preference among a group of captive bonobos (Pan paniscus). Subjects were 17 bonobos housed at the Columbus Zoo and Aquarium. Laterality of grooming was recorded using group scans; tool use was recorded using all-occurrence sampling. Grooming was characterized as unimanual or bimanual, and both tasks were scored as right-handed or left-handed. Most individuals did not exhibit significant hand preference for unimanual or bimanual (asymmetrical hand use) grooming, although 1 individual was lateralized for each. For the 8 subjects who engaged in termite fishing enough for statistical testing, 7 individuals exhibited significant laterality and strong individual hand preference. Four subjects preferred their left hand, 3 preferred their right, and 1 had no preference. Grooming, a simple behavior, was not lateralized in this group, yet a more complex behavior revealed a strong individual hand preference, and these results are congruent with other recent findings that demonstrate complex tasks elicit hand preference in bonobos. © 2017 S. Karger AG, Basel.

Variability and reduced performance of preschool- and early school-aged children on psychoacoustic tasks: What are the relevant factors?

NASA Astrophysics Data System (ADS)

Allen, Prudence

2003-04-01

Young children typically perform more poorly on psychoacoustic tasks than do adults, with large individual differences. When performance is averaged across children within age groups, the data suggest a gradual change in performance with increasing age. However, an examination of individual data suggests that the performance matures more rapidly, although at different times for different children. The mechanisms of development responsible for these changes are likely very complex, involving both sensory and cognitive processes. This paper will discuss some previously suggested mechanisms including attention and cue weighting, as well as possibilities suggested from more recent studies in which learning effects were examined. In one task, a simple frequency discrimination was required, while in another the listener was required to extract regularities in complex sequences of sounds that varied from trial to trial. Results suggested that the ability to select and consistently employ an effective listening strategy was especially important in the performance of the more complex task, while simple stimulus exposure and motivation contributed to the simpler task. These factors are important for understanding the perceptual development and for the subsequent application of psychoacoustic findings to clinical populations. [Work supported by the NSERC and the Canadian Language and Literacy Research Network.

Assuring reliability program effectiveness.

NASA Technical Reports Server (NTRS)

Ball, L. W.

1973-01-01

An attempt is made to provide simple identification and description of techniques that have proved to be most useful either in developing a new product or in improving reliability of an established product. The first reliability task is obtaining and organizing parts failure rate data. Other tasks are parts screening, tabulation of general failure rates, preventive maintenance, prediction of new product reliability, and statistical demonstration of achieved reliability. Five principal tasks for improving reliability involve the physics of failure research, derating of internal stresses, control of external stresses, functional redundancy, and failure effects control. A final task is the training and motivation of reliability specialist engineers.

Video-tracker trajectory analysis: who meets whom, when and where

NASA Astrophysics Data System (ADS)

Jäger, U.; Willersinn, D.

2010-04-01

Unveiling unusual or hostile events by observing manifold moving persons in a crowd is a challenging task for human operators, especially when sitting in front of monitor walls for hours. Typically, hostile events are rare. Thus, due to tiredness and negligence the operator may miss important events. In such situations, an automatic alarming system is able to support the human operator. The system incorporates a processing chain consisting of (1) people tracking, (2) event detection, (3) data retrieval, and (4) display of relevant video sequence overlaid by highlighted regions of interest. In this paper we focus on the event detection stage of the processing chain mentioned above. In our case, the selected event of interest is the encounter of people. Although being based on a rather simple trajectory analysis, this kind of event embodies great practical importance because it paves the way to answer the question "who meets whom, when and where". This, in turn, forms the basis to detect potential situations where e.g. money, weapons, drugs etc. are handed over from one person to another in crowded environments like railway stations, airports or busy streets and places etc.. The input to the trajectory analysis comes from a multi-object video-based tracking system developed at IOSB which is able to track multiple individuals within a crowd in real-time [1]. From this we calculate the inter-distances between all persons on a frame-to-frame basis. We use a sequence of simple rules based on the individuals' kinematics to detect the event mentioned above to output the frame number, the persons' IDs from the tracker and the pixel coordinates of the meeting position. Using this information, a data retrieval system may extract the corresponding part of the recorded video image sequence and finally allows for replaying the selected video clip with a highlighted region of interest to attract the operator's attention for further visual inspection.

A Simple Ultrasonic Experiment Using a Phase Shift Detection Technique.

ERIC Educational Resources Information Center

Yunus, W. Mahmood Mat; Ahmad, Maulana

1996-01-01

Describes a simple ultrasonic experiment that can be used to measure the purity of liquid samples by detecting variations in the velocity of sound. Uses a phase shift detection technique that incorporates the use of logic gates and a piezoelectric transducer. (JRH)

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.

Quantifying Phishing Susceptibility for Detection and Behavior Decisions.

PubMed

Canfield, Casey Inez; Fischhoff, Baruch; Davis, Alex

2016-12-01

We use signal detection theory to measure vulnerability to phishing attacks, including variation in performance across task conditions. Phishing attacks are difficult to prevent with technology alone, as long as technology is operated by people. Those responsible for managing security risks must understand user decision making in order to create and evaluate potential solutions. Using a scenario-based online task, we performed two experiments comparing performance on two tasks: detection, deciding whether an e-mail is phishing, and behavior, deciding what to do with an e-mail. In Experiment 1, we manipulated the order of the tasks and notification of the phishing base rate. In Experiment 2, we varied which task participants performed. In both experiments, despite exhibiting cautious behavior, participants' limited detection ability left them vulnerable to phishing attacks. Greater sensitivity was positively correlated with confidence. Greater willingness to treat e-mails as legitimate was negatively correlated with perceived consequences from their actions and positively correlated with confidence. These patterns were robust across experimental conditions. Phishing-related decisions are sensitive to individuals' detection ability, response bias, confidence, and perception of consequences. Performance differs when people evaluate messages or respond to them but not when their task varies in other ways. Based on these results, potential interventions include providing users with feedback on their abilities and information about the consequences of phishing, perhaps targeting those with the worst performance. Signal detection methods offer system operators quantitative assessments of the impacts of interventions and their residual vulnerability. © 2016, Human Factors and Ergonomics Society.

The Effect of Context Change on Simple Acquisition Disappears with Increased Training

ERIC Educational Resources Information Center

Leon, Samuel P.; Abad, Maria J. F.; Rosas, Juan M.

2010-01-01

The goal of this experiment was to assess the impact that experience with a task has on the context specificity of the learning that occurs. Participants performed an instrumental task within a computer game where different responses were performed in the presence of discriminative stimuli to obtain reinforcers. The number of training trials (3,…

Throwing Accuracy

ERIC Educational Resources Information Center

Cross, Rod

2018-01-01

A simple throwing task is described to illustrate various aspects of projectile motion. The task was to throw a tennis ball in a waste paper bin about 2 m away. Success depends on skill, but it also depends on the physics of the problem. If the ball is thrown underarm, then success depends primarily on the throw speed, which must be controlled to…

Age and Sex Differences in Intra-Individual Variability in a Simple Reaction Time Task

ERIC Educational Resources Information Center

Ghisletta, Paolo; Renaud, Olivier; Fagot, Delphine; Lecerf, Thierry; de Ribaupierre, Anik

2018-01-01

While age effects in reaction time (RT) tasks across the lifespan are well established for level of performance, analogous findings have started appearing also for indicators of intra-individual variability (IIV). Children are not only slower, but also display more variability than younger adults in RT. Yet, little is known about potential…

Reversing the Speed-IQ Correlation: Intra-Individual Variability and Attentional Control in the Inspection Time Paradigm

ERIC Educational Resources Information Center

Fox, Mark C.; Roring, Roy W.; Mitchum, Ainsley L.

2009-01-01

Elementary cognitive tasks (ECTs) are simple tasks involving basic cognitive processes for which speed of performance typically correlates with IQ. Inspection time (IT) has the strongest IQ correlations and is considered critical evidence for neural speed underlying individual differences in intelligence. However, results from Bors et al. [Bors,…

There Are at Least Two Kinds of Probability Matching: Evidence from a Secondary Task

ERIC Educational Resources Information Center

Otto, A. Ross; Taylor, Eric G.; Markman, Arthur B.

2011-01-01

Probability matching is a suboptimal behavior that often plagues human decision-making in simple repeated choice tasks. Despite decades of research, recent studies cannot find agreement on what choice strategies lead to probability matching. We propose a solution, showing that two distinct local choice strategies--which make different demands on…

Transfer of Training from Predictor to Conventional Displays. Interim Report.

ERIC Educational Resources Information Center

Wulfeck, J. W.

Use of a predictor display has been shown to virtually transform the difficulty of a variety of complex, manual control pursuit tracking tasks to the level of those having relatively simple control requirements. With 15-minutes practice, naive operators are able to perform some complex tasks with a predictor display at accuracy levels previously…

Intonational Rises and Dialog Acts in the Australian English Map Task.

ERIC Educational Resources Information Center

Fletcher, Janet; Stirling, Lesley; Mushin, Ilana; Wales, Roger

2002-01-01

Eight map task dialogs representative of general Australian English were coded for speaker turn and for dialog acts using a version of SWBD-DAMSL, a dialog act annotation scheme. High, low, simple, and complex rising tunes, and any corresponding dialog act codes were then compared. The Australian statement high rise (usually realized as a L…