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Sample records for dual task conditions

  1. Mind wandering in text comprehension under dual-task conditions.

    PubMed

    Dixon, Peter; Li, Henry

    2013-01-01

    In two experiments, subjects responded to on-task probes while reading under dual-task conditions. The secondary task was to monitor the text for occurrences of the letter e. In Experiment 1, reading comprehension was assessed with a multiple-choice recognition test; in Experiment 2, subjects recalled the text. In both experiments, the secondary task replicated the well-known "missing-letter effect" in which detection of e's was less effective for function words and the word "the." Letter detection was also more effective when subjects were on task, but this effect did not interact with the missing-letter effect. Comprehension was assessed in both the dual-task conditions and in control single-task conditions. In the single-task conditions, both recognition (Experiment 1) and recall (Experiment 2) was better when subjects were on task, replicating previous research on mind wandering. Surprisingly, though, comprehension under dual-task conditions only showed an effect of being on task when measured with recall; there was no effect on recognition performance. Our interpretation of this pattern of results is that subjects generate responses to on-task probes on the basis of a retrospective assessment of the contents of working memory. Further, we argue that under dual-task conditions, the contents of working memory is not closely related to the reading processes required for accurate recognition performance. These conclusions have implications for models of text comprehension and for the interpretation of on-task probe responses.

  2. Mind wandering in text comprehension under dual-task conditions

    PubMed Central

    Dixon, Peter; Li, Henry

    2013-01-01

    In two experiments, subjects responded to on-task probes while reading under dual-task conditions. The secondary task was to monitor the text for occurrences of the letter e. In Experiment 1, reading comprehension was assessed with a multiple-choice recognition test; in Experiment 2, subjects recalled the text. In both experiments, the secondary task replicated the well-known “missing-letter effect” in which detection of e's was less effective for function words and the word “the.” Letter detection was also more effective when subjects were on task, but this effect did not interact with the missing-letter effect. Comprehension was assessed in both the dual-task conditions and in control single-task conditions. In the single-task conditions, both recognition (Experiment 1) and recall (Experiment 2) was better when subjects were on task, replicating previous research on mind wandering. Surprisingly, though, comprehension under dual-task conditions only showed an effect of being on task when measured with recall; there was no effect on recognition performance. Our interpretation of this pattern of results is that subjects generate responses to on-task probes on the basis of a retrospective assessment of the contents of working memory. Further, we argue that under dual-task conditions, the contents of working memory is not closely related to the reading processes required for accurate recognition performance. These conclusions have implications for models of text comprehension and for the interpretation of on-task probe responses. PMID:24101909

  3. Healthy older adults balance pattern under dual task conditions: exploring the strategy and trend

    PubMed Central

    Zeynalzadeh Ghoochani, Bahareh; Hosseini, Seyed Ali; Talebian, Saeed; Biglarian, Akbar; Zeinalzadeh, Afsaneh; Nazary-Moghadam, Salman; Derakhshanrad, Seyed Alireza

    2016-01-01

    Background: In line with health promotion plans, early intervention and fall prevention in geriatric population, it is important to study healthy individuals balance mechanisms. The aim of this research was to investigate the effect of adding and removing visual input and dual task on elderly balance. Methods: Twenty healthy elderly recruited from four different senior citizen health club centers and from the University of Social Welfare and Rehabilitation Sciences (USWR) participated in this analytic cross-sectional study. At USWR’s Motor Control Laboratory, the participants’ postural sway were assessed using force plate in 4 distinct double leg standing conditions with and without presence of visual input and Stroop dual task. Postural and Stroop variables were compared. Results: Findings indicated that when the elderly encountered with either dual task or absence of visual input, they can still manage the situation in a way that changes in sway parameter would not become significant. But, when these two conditions occurred simultaneously, the participant’s balance strategy fluctuated. Therefore, the mean velocity showed a significant difference between the “single quiet standing” condition and the condition of standing with eyes closed while the participants were answering Stroop dual task (Mean difference = -0.007, 95% CI = -0.012, -0.002). Conclusion: It appears that velocity parameter is sensitive to small changes, so it is recommended that researchers include this parameter in their future analyses. Balance in elderly can be manipulated by dual task and visual input deprivation. PMID:27766239

  4. Parallel Response Selection Disrupts Sequence Learning under Dual-Task Conditions

    ERIC Educational Resources Information Center

    Schumacher, Eric H.; Schwarb, Hillary

    2009-01-01

    Some studies suggest that dual-task processing impairs sequence learning; others suggest it does not. The reason for this discrepancy remains obscure. It may have to do with the dual-task procedure often used. Many dual-task sequence learning studies pair the serial reaction time (SRT) task with a tone-counting secondary task. The tone-counting…

  5. Influence of age on postural sway during different dual-task conditions

    PubMed Central

    Bergamin, Marco; Gobbo, Stefano; Zanotto, Tobia; Sieverdes, John C.; Alberton, Cristine L.; Zaccaria, Marco; Ermolao, Andrea

    2014-01-01

    Dual-task performance assessments of competing parallel tasks and postural outcomes are growing in importance for geriatricians, as it is associated with predicting fall risk in older adults. This study aims to evaluate the postural stability during different dual-task conditions including visual (SMBT), verbal (CBAT) and cognitive (MAT) tasks in comparison with the standard Romberg's open eyes position (OE). Furthermore, these conditions were investigated in a sample of young adults and a group of older healthy subjects to examine a potential interaction between type of secondary task and age status. To compare these groups across the four conditions, a within-between mixed model ANOVA was applied. Thus, a stabilometric platform has been used to measure center of pressure velocity (CoPV), sway area (SA), antero-posterior (AP) and medio-lateral (ML) oscillations as extents of postural sway. Tests of within-subjects effects indicated that different four conditions influenced the static balance for CoPV (p < 0.001), SA (p < 0.001). Post-hoc analyses indicated that CBAT task induced the worst balance condition on CoPV and resulted in significantly worse scores than OE (−11.4%; p < 0.05), SMBT (−17.8%; p < 0.01) and MAT (−17.8%; p < 0.01) conditions; the largest SA was found in OE, and it was statistically larger than SMBT (−27.0%; p < 0.01) and MAT (−23.1%; p < 0.01). The between-subjects analysis indicated a general lower balance control in the group of elderly subjects (CoPV p < 0.001, SA p < 0.002), while, the mixed model ANOVA did not detect any interaction effect between types of secondary task and groups in any parameters (CoPV p = 0.154, SA p = 0.125). Postural sway during dual-task assessments was also found to decrease with advancing age, however, no interactions between aging and types of secondary tasks were found. Overall, these results indicated that the secondary task which most influenced the length of sway path, as measured by postural

  6. Influence of age on postural sway during different dual-task conditions.

    PubMed

    Bergamin, Marco; Gobbo, Stefano; Zanotto, Tobia; Sieverdes, John C; Alberton, Cristine L; Zaccaria, Marco; Ermolao, Andrea

    2014-01-01

    Dual-task performance assessments of competing parallel tasks and postural outcomes are growing in importance for geriatricians, as it is associated with predicting fall risk in older adults. This study aims to evaluate the postural stability during different dual-task conditions including visual (SMBT), verbal (CBAT) and cognitive (MAT) tasks in comparison with the standard Romberg's open eyes position (OE). Furthermore, these conditions were investigated in a sample of young adults and a group of older healthy subjects to examine a potential interaction between type of secondary task and age status. To compare these groups across the four conditions, a within-between mixed model ANOVA was applied. Thus, a stabilometric platform has been used to measure center of pressure velocity (CoPV), sway area (SA), antero-posterior (AP) and medio-lateral (ML) oscillations as extents of postural sway. Tests of within-subjects effects indicated that different four conditions influenced the static balance for CoPV (p < 0.001), SA (p < 0.001). Post-hoc analyses indicated that CBAT task induced the worst balance condition on CoPV and resulted in significantly worse scores than OE (-11.4%; p < 0.05), SMBT (-17.8%; p < 0.01) and MAT (-17.8%; p < 0.01) conditions; the largest SA was found in OE, and it was statistically larger than SMBT (-27.0%; p < 0.01) and MAT (-23.1%; p < 0.01). The between-subjects analysis indicated a general lower balance control in the group of elderly subjects (CoPV p < 0.001, SA p < 0.002), while, the mixed model ANOVA did not detect any interaction effect between types of secondary task and groups in any parameters (CoPV p = 0.154, SA p = 0.125). Postural sway during dual-task assessments was also found to decrease with advancing age, however, no interactions between aging and types of secondary tasks were found. Overall, these results indicated that the secondary task which most influenced the length of sway path, as measured by postural stability was a

  7. The relation between the Type A behavior pattern, pacing, and subjective workload under single- and dual-task conditions

    NASA Technical Reports Server (NTRS)

    Damos, D.

    1985-01-01

    Twenty Type A and 20 Type B subjects performed two discrete tasks alone and together. Half of the subjects performed paced versions of both tasks; half, unpaced versions. Workload ratings were obtained for all subjects under single- and dual-task conditions using eight bipolar adjective scales. Under single-task conditions there was a significant interaction between behavior pattern and pacing on one of the tasks. This interaction indicated that Type A subjects responded more rapidly under unpaced conditions than did Type B subjects, although there was little difference between the groups under paced conditions. Under dual-task conditions, Type A subjects responded more rapidly than did Type B subjects regardless of pacing. There was one significant interaction between behavior pattern and task on one of the workload scales.

  8. Sonification of in-vehicle interface reduces gaze movements under dual-task condition.

    PubMed

    Tardieu, Julien; Misdariis, Nicolas; Langlois, Sabine; Gaillard, Pascal; Lemercier, Céline

    2015-09-01

    In-car infotainment systems (ICIS) often degrade driving performances since they divert the driver's gaze from the driving scene. Sonification of hierarchical menus (such as those found in most ICIS) is examined in this paper as one possible solution to reduce gaze movements towards the visual display. In a dual-task experiment in the laboratory, 46 participants were requested to prioritize a primary task (a continuous target detection task) and to simultaneously navigate in a realistic mock-up of an ICIS, either sonified or not. Results indicated that sonification significantly increased the time spent looking at the primary task, and significantly decreased the number and the duration of gaze saccades towards the ICIS. In other words, the sonified ICIS could be used nearly exclusively by ear. On the other hand, the reaction times in the primary task were increased in both silent and sonified conditions. This study suggests that sonification of secondary tasks while driving could improve the driver's visual attention of the driving scene. PMID:25959316

  9. Orienting attention in visual working memory requires central capacity: Decreased retro-cue effects under dual-task conditions

    PubMed Central

    Berryhill, Marian E.

    2014-01-01

    The retro-cue effect (RCE) describes superior working memory performance for validly cued stimulus locations long after encoding has ended. Importantly, this happens with delays beyond the range of iconic memory. In general, the RCE is a stable phenomenon that emerges under varied stimulus configurations and timing parameters. We investigated its susceptibility to dual-task interference to determine the attentional requirements at the time point of cue onset and encoding. In Experiment 1, we compared single- with dual-task conditions. In Experiment 2, we borrowed from the psychological refractory period paradigm and compared conditions with high and low (dual-) task overlap. The secondary task was always binary tone discrimination requiring amanual response. Across both experiments, an RCE was found, but it was diminished in magnitude in the critical dual-task conditions. A previous study did not find evidence that sustained attention is required in the interval between cue offset and test. Our results apparently contradict these findings and point to a critical time period around cue onset and briefly thereafter during which attention is required. PMID:24452383

  10. The influence of dual-task conditions on movement in young adults with and without Down syndrome.

    PubMed

    Horvat, M; Croce, R; Tomporowski, P; Barna, M C

    2013-10-01

    This investigation compared spatial and temporal movement parameters of a sample of young adults with Down syndrome (DS) (N=12) and individuals without disabilities (IWD) (N=12) under dual-task conditions. Subjects performed a walking task at a preferred speed in isolation and again while holding a plate and cup, carrying tray and cups, talking on a phone, or buttoning a shirt. Spatial and temporal values were compared using a 2 (group) × 5 (conditions) repeated measures analysis of variance. Analysis of spatial components separately indicated that step length, step width, stride length and stride width revealed significant group and condition interactions (p ≤.01). Temporal components yielded significance in velocity and single-leg support time (p ≤.01). The current results support the notion that along with impairments to qualitative motor skills, individuals with DS are also impaired in higher order executive functioning (EF), as measured by a dual-task paradigm. It was concluded that movements are less efficient and functional in individuals with DS when an additional task is encountered while walking. We theorized that the motor program was sufficient for general locomotion but was not sufficiently developed to allow individuals with DS to modify or alter their movements to changing cognitive conditions that increasingly taxed EF. As gait and balance are trainable in this population, we recommend developing appropriate exercise and motor skill interventions during childhood and adolescents to increase strength, stability, and more "robust" ambulatory motor schema.

  11. Age-associated differences in global and segmental control during dual-task walking under sub-optimal sensory conditions.

    PubMed

    Deshpande, Nandini; Hewston, Patricia; Yoshikawa, Mika

    2015-04-01

    The ability to safely perform cognitive-motor dual-tasks is critical for independence of older adults. We compared age-associated differences in global and segmental control during dual-task walking in sub-optimal sensory conditions. Thirteen young (YA) and 13 healthy older (OA) adults walked a straight pathway with cognitive dual-task of walking-while-talking (WT) or no-WT under four sensory conditions. On randomly selected trials, visual and vestibular inputs were manipulated using blurring goggles (BV) and Galvanic Vestibular Stimulation (GVS), respectively. Gait speed decreased more in YA than OA during WT. Gait speed increased with GVS with normal vision but not BV. Step length considerably decreased with WT. Trunk roll significantly decreased only in OA with GVS in WT. Head roll significantly decreased with GVS regardless of age. Results indicate GVS-induced adaptations were dependent on available visual information. YA reduced their gait speed more than OA to achieve a similar pace to safely perform WT. GVS resulted in both age-groups to reduce head movement. However, with the addition of WT during GVS, OA also stiffened their trunk. Therefore, with increased attentional demands healthy OA employed different compensatory strategies than YA to maintain postural control.

  12. Impact of age and obstacles on navigation precision and reaction time during blind navigation in dual-task conditions.

    PubMed

    Richer, Natalie; Paquet, Nicole; Lajoie, Yves

    2014-03-01

    Navigation without vision is a skill that is often employed in our daily lives, such as walking in the dark at night. Navigating without vision to a remembered target has previously been studied. However, little is known about the impact of age or obstacles on the attentional demands of a blind navigation task. This study examined the impacts of age and obstacles on reaction time (RT) and navigation precision during blind navigation in dual-task conditions. The aims were to determine the effects of age, obstacles, and auditory stimulus location on RT and navigation precision in a blind navigation task. Ten healthy young adults (24.5±2.5 years) and ten healthy older adults (69.5±2.9 years) participated in the study. Participants were asked to walk to a target located 8m ahead. In half the trials, the path was obstructed with hanging obstacles. Participants performed this task in the absence of vision, while executing a discrete RT task. Results demonstrated that older adults presented increased RT, linear distance travelled (LDT), and obstacle contact; that obstacle presence significantly increased RT compared to trials with no obstacles; and that an auditory stimulus emitted early versus late in the path increased LDT. Results suggest that the attentional demands of blind navigation are higher in older than young adults, as well as when obstacles are present. Furthermore, navigation precision is affected by age and when participants are distracted by the secondary task early in navigation, presumably because the secondary task interferes with path estimation.

  13. Fear of falling is associated with prolonged anticipatory postural adjustment during gait initiation under dual-task conditions in older adults.

    PubMed

    Uemura, Kazuki; Yamada, Minoru; Nagai, Koutatsu; Tanaka, Buichi; Mori, Shuhei; Ichihashi, Noriaki

    2012-02-01

    Little is known about dynamic balance control under dual-task conditions in older adults with fear of falling (FoF). The purpose of this study was to examine the effect of FoF on anticipatory postural adjustment (APA) during gait initiation under dual-task conditions in older adults. Fifty-seven elderly volunteers (age, 79.2 [6.8] years) from the community participated in this study. Each participant was categorised into either the Fear (n=24) or No-fear (n=33) group on the basis of the presence or absence of FoF. Under single- and dual-task conditions, centre of pressure (COP) data were collected while the participants performed gait initiation trials from a starting position on a force platform. We also performed a 10-m walking test (WT), a timed up & go test (TUG), and a functional reach test (FR). The reaction and APA phases were measured from the COP data. The results showed that under the dual-task condition, the Fear group had significantly longer APA phases than the No-fear group, although no significant differences were observed between the 2 groups in the reaction and APA phases under the single-task condition and in any clinical measurements (WT, TUG, and FR). Our findings suggest that specific deficits in balance control occur in subjects with FoF during gait initiation while dual tasking, even if their physical functions are comparable to subjects without FoF.

  14. The effect of a cognitive-motor intervention on voluntary step execution under single and dual task conditions in older adults: a randomized controlled pilot study

    PubMed Central

    Pichierri, Giuseppe; Coppe, Amos; Lorenzetti, Silvio; Murer, Kurt; de Bruin, Eling D

    2012-01-01

    Background This randomized controlled pilot study aimed to explore whether a cognitive-motor exercise program that combines traditional physical exercise with dance video gaming can improve the voluntary stepping responses of older adults under attention demanding dual task conditions. Methods Elderly subjects received twice weekly cognitive-motor exercise that included progressive strength and balance training supplemented by dance video gaming for 12 weeks (intervention group). The control group received no specific intervention. Voluntary step execution under single and dual task conditions was recorded at baseline and post intervention (Week 12). Results After intervention between-group comparison revealed significant differences for initiation time of forward steps under dual task conditions (U = 9, P = 0.034, r = 0.55) and backward steps under dual task conditions (U = 10, P = 0.045, r = 0.52) in favor of the intervention group, showing altered stepping levels in the intervention group compared to the control group. Conclusion A cognitive-motor intervention based on strength and balance exercises with additional dance video gaming is able to improve voluntary step execution under both single and dual task conditions in older adults. PMID:22865999

  15. Children Age 7 Complete Complex Gait and Postural Tasks Differently Than Adults Under Dual-Task Conditions.

    PubMed

    Hinton, Dorelle C; Vallis, Lori Ann

    2016-01-01

    Healthy children (7 years old) and adults (20 years old) completed a simultaneous balancing, reaching, and cognitive task while standing and during gait. Cognitive accuracy rate for children and adults was similar for both postures; however, response latency was greater for children than adults. While standing, trunk, upper arm, and forearm segments moved as individual segments in adults; however, articulated control of the upper arm and forearm in children was not evident. Adults and children showed evidence of articulated segmental control during gait. Absolute gait velocity (m/s) was significantly slower for children; however, there was no effect of age on step length. Children 7 years old can perform a simultaneous motor and cognitive task but their performance strategies do not yet match young adults. PMID:26305113

  16. Task Prioritization in Dual-Tasking: Instructions versus Preferences.

    PubMed

    Jansen, Reinier J; van Egmond, René; de Ridder, Huib

    2016-01-01

    The role of task prioritization in performance tradeoffs during multi-tasking has received widespread attention. However, little is known on whether people have preferences regarding tasks, and if so, whether these preferences conflict with priority instructions. Three experiments were conducted with a high-speed driving game and an auditory memory task. In Experiment 1, participants did not receive priority instructions. Participants performed different sequences of single-task and dual-task conditions. Task performance was evaluated according to participants' retrospective accounts on preferences. These preferences were reformulated as priority instructions in Experiments 2 and 3. The results showed that people differ in their preferences regarding task prioritization in an experimental setting, which can be overruled by priority instructions, but only after increased dual-task exposure. Additional measures of mental effort showed that performance tradeoffs had an impact on mental effort. The interpretation of these findings was used to explore an extension of Threaded Cognition Theory with Hockey's Compensatory Control Model. PMID:27391779

  17. Task Prioritization in Dual-Tasking: Instructions versus Preferences

    PubMed Central

    Jansen, Reinier J.; van Egmond, René; de Ridder, Huib

    2016-01-01

    The role of task prioritization in performance tradeoffs during multi-tasking has received widespread attention. However, little is known on whether people have preferences regarding tasks, and if so, whether these preferences conflict with priority instructions. Three experiments were conducted with a high-speed driving game and an auditory memory task. In Experiment 1, participants did not receive priority instructions. Participants performed different sequences of single-task and dual-task conditions. Task performance was evaluated according to participants’ retrospective accounts on preferences. These preferences were reformulated as priority instructions in Experiments 2 and 3. The results showed that people differ in their preferences regarding task prioritization in an experimental setting, which can be overruled by priority instructions, but only after increased dual-task exposure. Additional measures of mental effort showed that performance tradeoffs had an impact on mental effort. The interpretation of these findings was used to explore an extension of Threaded Cognition Theory with Hockey’s Compensatory Control Model. PMID:27391779

  18. Task Prioritization in Dual-Tasking: Instructions versus Preferences.

    PubMed

    Jansen, Reinier J; van Egmond, René; de Ridder, Huib

    2016-01-01

    The role of task prioritization in performance tradeoffs during multi-tasking has received widespread attention. However, little is known on whether people have preferences regarding tasks, and if so, whether these preferences conflict with priority instructions. Three experiments were conducted with a high-speed driving game and an auditory memory task. In Experiment 1, participants did not receive priority instructions. Participants performed different sequences of single-task and dual-task conditions. Task performance was evaluated according to participants' retrospective accounts on preferences. These preferences were reformulated as priority instructions in Experiments 2 and 3. The results showed that people differ in their preferences regarding task prioritization in an experimental setting, which can be overruled by priority instructions, but only after increased dual-task exposure. Additional measures of mental effort showed that performance tradeoffs had an impact on mental effort. The interpretation of these findings was used to explore an extension of Threaded Cognition Theory with Hockey's Compensatory Control Model.

  19. Crossmodal action selection: evidence from dual-task compatibility.

    PubMed

    Huestegge, Lynn; Koch, Iring

    2010-06-01

    Response-related mechanisms of multitasking were studied by analyzing simultaneous processing of responses in different modalities (i.e., crossmodal action). Participants responded to a single auditory stimulus with a saccade, a manual response (single-task conditions), or both (dual-task condition). We used a spatially incompatible stimulus-response mapping for one task, but not for the other. Critically, inverting these mappings varied temporal task overlap in dual-task conditions while keeping spatial incompatibility across responses constant. Unlike previous paradigms, temporal task overlap was manipulated without utilizing sequential stimulus presentation, which might induce strategic serial processing. The results revealed dual-task costs, but these were not affected by an increase of temporal task overlap. This finding is evidence for parallel response selection in multitasking. We propose that crossmodal action is processed by a central mapping-selection mechanism in working memory and that the dual-task costs are mainly caused by mapping-related crosstalk.

  20. The functional neuroanatomy of multitasking: combining dual tasking with a short term memory task.

    PubMed

    Deprez, Sabine; Vandenbulcke, Mathieu; Peeters, Ron; Emsell, Louise; Amant, Frederic; Sunaert, Stefan

    2013-09-01

    Insight into the neural architecture of multitasking is crucial when investigating the pathophysiology of multitasking deficits in clinical populations. Presently, little is known about how the brain combines dual-tasking with a concurrent short-term memory task, despite the relevance of this mental operation in daily life and the frequency of complaints related to this process, in disease. In this study we aimed to examine how the brain responds when a memory task is added to dual-tasking. Thirty-three right-handed healthy volunteers (20 females, mean age 39.9 ± 5.8) were examined with functional brain imaging (fMRI). The paradigm consisted of two cross-modal single tasks (a visual and auditory temporal same-different task with short delay), a dual-task combining both single tasks simultaneously and a multi-task condition, combining the dual-task with an additional short-term memory task (temporal same-different visual task with long delay). Dual-tasking compared to both individual visual and auditory single tasks activated a predominantly right-sided fronto-parietal network and the cerebellum. When adding the additional short-term memory task, a larger and more bilateral frontoparietal network was recruited. We found enhanced activity during multitasking in components of the network that were already involved in dual-tasking, suggesting increased working memory demands, as well as recruitment of multitask-specific components including areas that are likely to be involved in online holding of visual stimuli in short-term memory such as occipito-temporal cortex. These results confirm concurrent neural processing of a visual short-term memory task during dual-tasking and provide evidence for an effective fMRI multitasking paradigm.

  1. Reduction of Dual-task Costs by Noninvasive Modulation of Prefrontal Activity in Healthy Elders

    PubMed Central

    Manor, Brad; Zhou, Junhong; Jor'dan, Azizah; Zhang, Jue; Fang, Jing; Pascual-Leone, Alvaro

    2016-01-01

    Dual tasking (e.g., walking or standing while performing a cognitive task) disrupts performance in one or both tasks, and such dual-task costs increase with aging into senescence. Dual tasking activates a network of brain regions including pFC. We therefore hypothesized that facilitation of prefrontal cortical activity via transcranial direct current stimulation (tDCS) would reduce dual-task costs in older adults. Thirty-seven healthy older adults completed two visits during which dual tasking was assessed before and after 20 min of real or sham tDCS targeting the left pFC. Trials of single-task standing, walking, and verbalized serial subtractions were completed, along with dual-task trials of standing or walking while performing serial subtractions. Dual-task costs were calculated as the percent change in markers of gait and postural control and serial subtraction performance, from single to dual tasking. Significant dual-task costs to standing, walking, and serial subtraction performance were observed before tDCS (p < .01). These dual-task costs were less after real tDCS as compared with sham tDCS as well as compared with either pre-tDCS condition (p < .03). Further analyses indicated that tDCS did not alter single task performance but instead improved performance solely within dual-task conditions (p < .02). These results demonstrate that dual tasking can be improved by modulating prefrontal activity, thus indicating that dual-task decrements are modifiable and may not necessarily reflect an obligatory consequence of aging. Moreover, tDCS may ultimately serve as a novel approach to preserving dual-task capacity into senescence. PMID:26488591

  2. The Effect of Dual Task Demands and Proficiency on Second Language Speech Production

    ERIC Educational Resources Information Center

    Declerck, Mathieu; Kormos, Judit

    2012-01-01

    In this study we examined how the introduction of a parallel finger-tapping task influences second language (L2) speech encoding mechanisms and monitoring processes, and how the level of proficiency impacts the efficiency and accuracy of L2 performance under single and dual task conditions. The results indicate that imposing dual task demands had…

  3. Working Memory and Postural Control: Adult Age Differences in Potential for Improvement, Task Priority, and Dual Tasking

    PubMed Central

    Rapp, Michael A.; Krampe, Ralf Th.

    2009-01-01

    We investigate dynamic posture control and working memory (NBack) retest practice in young and older adults, focusing on older adults' potential for improvement in the component tasks but more importantly in dual-task performance. Participants performed the 2 tasks in 11 sessions under single- and dual-task conditions. Posture improvement was observed with retest practice for both groups. Increase in cognitive load after initial practice led to greater dual-task costs in both tasks in older adults and higher costs in memory in young adults. With continued practice, costs were reduced by both groups; however, the 2 groups focused improvement on different tasks: Older adults focused on posture but young adults on cognition. These results emphasize older adults’ potential for improvement in dual-task performance and their flexibility to utilize the practice gains in posture to optimize cognitive performance. PMID:19255088

  4. Dual-task costs in aging are predicted by formal education.

    PubMed

    Vallesi, Antonino

    2016-10-01

    The capacity to manage different concurrent tasks at the same time decays in older adults. There is however a considerable amount of inter-individual variability in this capacity even in healthy aging. The purpose of this empirical study is to investigate which factors help explaining this variability. A dual-task paradigm was administered to 64 older adults and 31 younger controls. In this paradigm, a primary simple response time task had to be carried out either by itself (single-task condition) or while concurrently performing a secondary subtraction task (dual-task condition). Dual-task costs were operationalized by comparing dual-task and single-task conditions. Older adults showed higher dual-task interference than younger controls. Within the older group, the influence of age, general cognitive abilities, performance on the secondary task, and years of formal education was assessed with a multiple regression analysis. The results showed that years of formal education in older adults were the best predictor that significantly explained a portion of the variance in dual-task performance. These findings extend previous literature by showing that formal education provides an important dose of cognitive reserve, which is useful to successfully implement cognitive dual-task management despite aging.

  5. Biomechanical Analyses of Stair-climbing while Dual-tasking

    PubMed Central

    Vallabhajosula, Srikant; Tan, Chi Wei; Mukherjee, Mukul; Davidson, Austin J.; Stergiou, Nicholas

    2015-01-01

    Stair-climbing while doing a concurrent task like talking or holding an object is a common activity of daily living which poses high risk for falls. While biomechanical analyses of overground walking during dual-tasking have been studied extensively, little is known on the biomechanics of stair-climbing while dual-tasking. We sought to determine the impact of performing a concurrent cognitive or motor task during stair-climbing. We hypothesized that a concurrent cognitive task will have a greater impact on stair climbing performance compared to a concurrent motor task and that this impact will be greater on a higher-level step. Ten healthy young adults performed 10 trials of stair-climbing each under four conditions: stair ascending only, stair ascending and performing subtraction of serial sevens from a three-digit number, stair ascending and carrying an empty opaque box and stair ascending, performing subtraction of serial sevens from a random three-digit number and carrying an empty opaque box. Kinematics (lower extremity joint angles and minimum toe clearance) and kinetics (ground reaction forces and joint moments and powers) data were collected. We found that a concurrent cognitive task impacted kinetics but not kinematics of stair-climbing. The effect of dual-tasking during stair ascent also seemed to vary based on the different phases of stair ascent stance and seem to have greater impact as one climbs higher. Overall, the results of the current study suggest that the association between the executive functioning and motor task (like gait) becomes stronger as the level of complexity of the motor task increases. PMID:25773590

  6. Biomechanical analyses of stair-climbing while dual-tasking.

    PubMed

    Vallabhajosula, Srikant; Tan, Chi Wei; Mukherjee, Mukul; Davidson, Austin J; Stergiou, Nicholas

    2015-04-13

    Stair-climbing while doing a concurrent task like talking or holding an object is a common activity of daily living which poses high risk for falls. While biomechanical analyses of overground walking during dual-tasking have been studied extensively, little is known on the biomechanics of stair-climbing while dual-tasking. We sought to determine the impact of performing a concurrent cognitive or motor task during stair-climbing. We hypothesized that a concurrent cognitive task will have a greater impact on stair climbing performance compared to a concurrent motor task and that this impact will be greater on a higher-level step. Ten healthy young adults performed 10 trials of stair-climbing each under four conditions: stair ascending only, stair ascending and performing subtraction of serial sevens from a three-digit number, stair ascending and carrying an empty opaque box and stair ascending, performing subtraction of serial sevens from a random three-digit number and carrying an empty opaque box. Kinematics (lower extremity joint angles and minimum toe clearance) and kinetics (ground reaction forces and joint moments and powers) data were collected. We found that a concurrent cognitive task impacted kinetics but not kinematics of stair-climbing. The effect of dual-tasking during stair ascent also seemed to vary based on the different phases of stair ascent stance and seem to have greater impact as one climbs higher. Overall, the results of the current study suggest that the association between the executive functioning and motor task (like gait) becomes stronger as the level of complexity of the motor task increases.

  7. The capacity constraint in the prefrontal and parietal regions for coordinating dual arithmetic tasks.

    PubMed

    Kuo, Bo-Cheng; Yeh, Yei-Yu; Chen, Der-Yow; Liang, Keng Chen; Chen, Jyh-Horng

    2008-03-14

    Using a dual-serial-arithmetic paradigm, we examined whether a capacity limitation constrains the neural activation that underlies dual-task performance. Six conditions were run in the experiment (the baseline, single-addition, single-subtraction, dual-addition, dual-subtraction, and the dual-operation condition). In the baseline condition, participants were asked to remember the initial pair of numbers and ignore subsequent stimuli. In the single-addition and single-subtraction conditions, participants had to calculate a running total over a series of stimuli. In the dual-addition and dual-subtraction conditions, they had to do two arithmetic tasks involving the same operand (e.g., + 2 and + 7, - 3 and - 5). Participants performed one addition and one subtraction task (e.g., + 2 and - 7, - 3 and + 5) in the dual-operation condition. The functional magnetic resonance imaging results showed strict left prefrontal and parietal regions in the single-addition condition and bilateral activation in the single-subtraction condition. Greater activation in the prefrontal and parietal regions was observed in both the dual-operation condition and the dual-addition condition in comparison to the single-addition condition. No greater activation was observed in either the dual-operation condition or dual-subtraction condition in comparison to the single-subtraction condition. These results suggest a constraint imposed by a limit in capacity for the neural activity subserving dual-task performance when one of the tasks places high resource demands on the executive network.

  8. Investigating Perfect Timesharing: The Relationship between IM-Compatible Tasks and Dual-Task Performance

    ERIC Educational Resources Information Center

    Halvorson, Kimberly M.; Ebner, Herschel; Hazeltine, Eliot

    2013-01-01

    Why are dual-task costs reduced with ideomotor (IM) compatible tasks (Greenwald & Shulman, 1973; Lien, Proctor & Allen, 2002)? In the present experiments, we first examine three different measures of single-task performance (pure single-task blocks, mixed blocks, and long stimulus onset asynchrony [SOA] trials in dual-task blocks) and two measures…

  9. Instructions and skill level influence reliability of dual-task performance in young adults.

    PubMed

    Plummer, Prudence; Grewal, Gurtej; Najafi, Bijan; Ballard, Amy

    2015-05-01

    The purpose of this study was to assess the trial-to-trial repeatability of dual-task performance and establish the minimal detectable change (MDC95) of gait-related dual-task interference. Thirty-one healthy young adults (22.5, SD 2.1 years) performed texting and walking tasks in isolation (single-task) and in combination (dual-task). The dual-task was repeated with three different instructional sets regarding how attention should be prioritized (no-priority, gait-priority, texting-priority) in two different environments (low-distraction, high-distraction). Participants performed two trials for each condition. Trial-to-trial repeatability of gait speed, texting speed, texting accuracy, and the relative dual-task effects (DTE) on each was examined using intraclass correlation coefficients and standard error of measurement. MDC95 scores were also computed for each performance measure. Among young adults, reliability of gait speed in a challenging dual-task situation is excellent, even in a high-distraction environment. In the absence of specific task prioritization instructions, changes in dual-task gait speed greater than 0.15m/s or 11.9% DTE represent real change. Reliability of the more novel, non-gait task has poor to good reliability. Dual-task effects are more reliable when participants are given specific instructions about how to prioritize their attention. The findings also suggest that reliability of dual-task performance in a novel or challenging task is greater when individuals are more skilled at the task. Implications for clinical assessment of dual-task performance are discussed. PMID:25891529

  10. The effects of dual tasking on handwriting in patients with Parkinson's disease.

    PubMed

    Broeder, S; Nackaerts, E; Nieuwboer, A; Smits-Engelsman, B C M; Swinnen, S P; Heremans, E

    2014-03-28

    Previous studies have shown that patients with Parkinson's disease (PD) experience extensive problems during dual tasking. Up to now, dual-task interference in PD has mainly been investigated in the context of gait research. However, the simultaneous performance of two different tasks is also a prerequisite to efficiently perform many other tasks in daily life, including upper limb tasks. To address this issue, this study investigated the effect of a secondary cognitive task on the performance of handwriting in patients with PD. Eighteen PD patients and 11 age-matched controls performed a writing task involving the production of repetitive loops under single- and dual-task conditions. The secondary task consisted of counting high and low tones during writing. The writing tests were performed with two amplitudes (0.6 and 1.0cm) using a writing tablet. Results showed that dual-task performance was affected in PD patients versus controls. Dual tasking reduced writing amplitude in PD patients, but not in healthy controls (p=0.046). Patients' writing size was mainly reduced during the small-amplitude condition (small amplitude p=0.017; large amplitude p=0.310). This suggests that the control of writing at small amplitudes requires more compensational brain-processing recourses in PD and is as such less automatic than writing at large amplitudes. In addition, there was a larger dual-task effect on the secondary task in PD patients than controls (p=0.025). The writing tests on the writing tablet proved highly correlated to daily life writing as measured by the 'Systematic Screening of Handwriting Difficulties' test (SOS-test) and other manual dexterity tasks, particularly during dual-task conditions. Taken together, these results provide additional insights into the motor control of handwriting and the effects of dual tasking during upper limb movements in patients with PD. PMID:24447597

  11. Walking Stroop carpet: an innovative dual-task concept for detecting cognitive impairment

    PubMed Central

    Perrochon, A; Kemoun, G; Watelain, E; Berthoz, A

    2013-01-01

    Background Several studies have reported the potential value of the dual-task concept during locomotion in clinical evaluation because cognitive decline is strongly associated with gait abnormalities. However, current dual-task tests appear to be insufficient for early diagnosis of cognitive impairment. Methods Forty-nine subjects (young, old, with or without mild cognitive impairment) underwent cognitive evaluation (Mini-Mental State Examination, Frontal Assessment Battery, five-word test, Stroop, clock-drawing) and single-task locomotor evaluation on an electronic walkway. They were then dual-task-tested on the Walking Stroop carpet, which is an adaptation of the Stroop color–word task for locomotion. A cluster analysis, followed by an analysis of variance, was performed to assess gait parameters. Results Cluster analysis of gait parameters on the Walking Stroop carpet revealed an interaction between cognitive and functional abilities because it made it possible to distinguish dysexecutive cognitive fragility or decline with a sensitivity of 89% and a specificity of 94%. Locomotor abilities differed according to the group and dual-task conditions. Healthy subjects performed less well on dual-tasking under reading conditions than when they were asked to distinguish colors, whereas dysexecutive subjects had worse motor performances when they were required to dual task. Conclusion The Walking Stroop carpet is a dual-task test that enables early detection of cognitive fragility that has not been revealed by traditional neuropsychological tests or single-task walking analysis. PMID:23682211

  12. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight.

  13. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest.

    PubMed

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A; De Dios, Yiri E; Gadd, Nichole E; Wood, Scott J; Riascos, Roy; Kofman, Igor S; Bloomberg, Jacob J; Mulavara, Ajitkumar P; Seidler, Rachael D

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  14. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  15. Persistency and flexibility of complex brain networks underlie dual-task interference.

    PubMed

    Alavash, Mohsen; Hilgetag, Claus C; Thiel, Christiane M; Gießing, Carsten

    2015-09-01

    Previous studies on multitasking suggest that performance decline during concurrent task processing arises from interfering brain modules. Here, we used graph-theoretical network analysis to define functional brain modules and relate the modular organization of complex brain networks to behavioral dual-task costs. Based on resting-state and task fMRI we explored two organizational aspects potentially associated with behavioral interference when human subjects performed a visuospatial and speech task simultaneously: the topological overlap between persistent single-task modules, and the flexibility of single-task modules in adaptation to the dual-task condition. Participants showed a significant decline in visuospatial accuracy in the dual-task compared with single visuospatial task. Global analysis of topological similarity between modules revealed that the overlap between single-task modules significantly correlated with the decline in visuospatial accuracy. Subjects with larger overlap between single-task modules showed higher behavioral interference. Furthermore, lower flexible reconfiguration of single-task modules in adaptation to the dual-task condition significantly correlated with larger decline in visuospatial accuracy. Subjects with lower modular flexibility showed higher behavioral interference. At the regional level, higher overlap between single-task modules and less modular flexibility in the somatomotor cortex positively correlated with the decline in visuospatial accuracy. Additionally, higher modular flexibility in cingulate and frontal control areas and lower flexibility in right-lateralized nodes comprising the middle occipital and superior temporal gyri supported dual-tasking. Our results suggest that persistency and flexibility of brain modules are important determinants of dual-task costs. We conclude that efficient dual-tasking benefits from a specific balance between flexibility and rigidity of functional brain modules.

  16. Dual-Task Interference When A Response is Not Required

    NASA Technical Reports Server (NTRS)

    VanSelst, Mark; Johnston, James C.; Shafto, Michael (Technical Monitor)

    2002-01-01

    When subjects are required to respond to two stimuli presented in rapid succession, responses to the second stimulus are delayed. Such dual-task interference has been attributed to a fundamental processing bottleneck preventing simultaneous processing on both tasks. Two experiments show dual-task interference even when the first task does not require a response. The observed interference is caused by a bottleneck in central cognitive processing, rather than in response initiation or execution.

  17. Consistency and cost of dual-task gait balance measure in healthy adolescents and young adults.

    PubMed

    Howell, David R; Osternig, Louis R; Chou, Li-Shan

    2016-09-01

    Matched control data are commonly used to examine recovery from concussion. Limited data exist, however, examining dual-task gait data consistency collected over time in healthy individuals. The study purposes were to: 1) assess the consistency of single-task and dual-task gait balance control measures, 2) determine the minimal detectable change (MDC) of gait balance control measures, and 3) examine the extent to which age and task complexity affect dual-task walking costs in healthy adolescents and young adults. Twenty-four adolescent (mean age=15.5±1.1years) and 21 young adult (mean age=21.2±4.5years) healthy participants completed 5 testing sessions across a two-month period, which involved analyses of gait balance control and temporal-distance variables during single-task and dual-task walking conditions in a motion analysis laboratory. Cronbach's α and MDCs were used to determine the consistency of the gait balance control variables and the smallest amount of change required to distinguish true performance from change due to the performance/measurement variability, respectively. Dual-task costs were evaluated to determine the effect of task complexity and age across time using 3-way ANOVAs. Good to excellent test-retest consistency was found for all single-task and dual-task walking (Cronbach's α range: 0.764-0.970), with a center-of-mass medial-lateral displacement MDC range of 0.835-0.948cm. Greater frontal plane dual-task costs were observed during more complex secondary tasks (p<0.001). The results revealed good-excellent consistency across testing sessions for all variables and indicated dual-task costs are affected by task complexity. Thus, healthy controls can be effective comparators when assessing injured subjects.

  18. Operation Compatibility: A Neglected Contribution to Dual-Task Costs

    ERIC Educational Resources Information Center

    Pannebakker, Merel M.; Band, Guido P. H.; Ridderinkhof, K. Richard

    2009-01-01

    Traditionally, dual-task interference has been attributed to the consequences of task load exceeding capacity limitations. However, the current study demonstrates that in addition to task load, the mutual compatibility of the concurrent processes modulates whether 2 tasks can be performed in parallel. In 2 psychological refractory period…

  19. Investigating perfect timesharing: the relationship between IM-compatible tasks and dual-task performance.

    PubMed

    Halvorson, Kimberly M; Ebner, Herschel; Hazeltine, Eliot

    2013-04-01

    Why are dual-task costs reduced with ideomotor (IM) compatible tasks (Greenwald & Shulman, 1973; Lien, Proctor & Allen, 2002)? In the present experiments, we first examine three different measures of single-task performance (pure single-task blocks, mixed blocks, and long stimulus onset asynchrony [SOA] trials in dual-task blocks) and two measures of dual-task performance (simultaneous stimulus presentation blocks and simultaneous stimulus presentation trials in blocks with mixed SOAs), and show that these different measures produce different estimates of the cost. Next we examine whether the near elimination of costs can be explained by assuming that one or both of the tasks bypasses capacity-limited central operations. The results indicate that both tasks must be IM-compatible to nearly eliminate the dual-task costs, suggesting that the relationship between the tasks plays a critical role in overlapping performance. PMID:22866763

  20. Physiological Synchronization in a Vigilance Dual Task.

    PubMed

    Guastello, Stephen J

    2016-01-01

    The synchronization of autonomic arousal levels and other physio-logical responses between people is a potentially important component of work team performance, client-therapist relationships, and other types of human interaction. This study addressed several problems: What statistical models are viable for identifying synchronization for loosely coupled human systems? How is the level of synchronization related to psychosocial variables such as empathy, subjective ratings of workload, and actual performance? Participants were 70 undergraduates who worked in pairs on a vigilance dual task in which they watched a virtual reality security camera, rang a bell when they saw the target intruder, and completed a jig-saw puzzle. Event rates either increased or decreased during the 90 min work period. The average R2 values for each person were .66, .66, .62, and .53 for the linear autoregressive model, linear autoregressive model with a synchronization component, the nonlinear autoregressive model, and the nonlinear autoregressive model with a synchronization component, respectively. All models were more accurate at a lag of 20 sec compared to 50 sec or customized lag lengths. Although the linear models were more accurate overall, the nonlinear synchronization parameters were more often related to psychological variables and performance. In particular, greater synchronization was observed with the nonlinear model when the target event rate increased, compared to when it decreased, which was expected from the general theory of synchronization. Nonlinear models were also more effective for uncovering inhibitory or dampening relationships between the co-workers as well as mutually excitatory relationships. Future research should explore the comparative model results for tasks that induce higher levels of synchronization and involve different types of internal group coordination.

  1. Dual-tasking postural control in patients with right brain damage.

    PubMed

    Bourlon, Clémence; Lehenaff, Laurent; Batifoulier, Cécile; Bordier, Aurélie; Chatenet, Aurélia; Desailly, Eric; Fouchard, Christian; Marsal, Muriel; Martinez, Marianne; Rastelli, Federica; Thierry, Anaïs; Bartolomeo, Paolo; Duret, Christophe

    2014-01-01

    The control of dual-tasking effects is a daily challenge in stroke neurorehabilitation. It maybe one of the reasons why there is poor functional prognosis after a stroke in the right hemisphere, which plays a dominant role in posture control. The purpose of this study was to explore cognitive motor interference in right brain-lesioned and healthy subjects maintaining a standing position while performing three different tasks: a control task, a simple attentional task and a complex attentional task. We measured the sway area of the subjects on a force platform, including the center of pressure and its displacements. Results showed that stroke patients presented a reduced postural sway compared to healthy subjects, who were able to maintain their posture while performing a concomitant attentional task in the same dual-tasking conditions. Moreover, in both groups, the postural sway decreased with the increase in attentional load from cognitive tasks. We also noticed that the stability of stroke patients in dual-tasking conditions increased together with the weight-bearing rightward deviation, especially when the attentional load of the cognitive tasks and lower limb motor impairments were high. These results suggest that stroke patients and healthy subjects adopt a similar postural regulation pattern aimed at maintaining stability in dual-tasking conditions involving a static standing position and different attention-related cognitive tasks. Our results indicate that attention processes might facilitate static postural control.

  2. The effect of cognitive aging on implicit sequence learning and dual tasking.

    PubMed

    Vandenbossche, Jochen; Coomans, Daphné; Homblé, Koen; Deroost, Natacha

    2014-01-01

    We investigated the influence of attentional demands on sequence-specific learning by means of the serial reaction time task (Nissen and Bullemer, 1987) in young (age 18-25) and aged (age 55-75) adults. Participants had to respond as fast as possible to a stimulus presented in one of four horizontal locations by pressing a key corresponding to the spatial position of the stimulus. During the training phase sequential blocks were accompanied by (1) no secondary task (single), (2) a secondary tone counting task (dual tone), or (3) a secondary shape counting task (dual shape). Both secondary tasks were administered to investigate whether low and high interference tasks interact with implicit learning and age. The testing phase, under baseline single condition, was implemented to assess differences in sequence-specific learning between young and aged adults. Results indicate that (1) aged subjects show less sequence learning compared to young adults, (2) young participants show similar implicit learning effects under both single and dual task conditions when we account for explicit awareness, and (3) aged adults demonstrate reduced learning when the primary task is accompanied with a secondary task, even when explicit awareness is included as a covariate in the analysis. These findings point to implicit learning deficits under dual task conditions that can be related to cognitive aging, demonstrating the need for sufficient cognitive resources while performing a sequence learning task.

  3. An Investigation of Response and Stimulus Modality Transfer Effects after Dual-Task Training in Younger and Older

    PubMed Central

    Lussier, Maxime; Gagnon, Christine; Bherer, Louis

    2012-01-01

    It has been shown that dual-task training leads to significant improvement in dual-task performance in younger and older adults. However, the extent to which training benefits to untrained tasks requires further investigation. The present study assessed (a) whether dual-task training leads to cross-modality transfer in untrained tasks using new stimuli and/or motor responses modalities, (b) whether transfer effects are related to improved ability to prepare and maintain multiple task-set and/or enhanced response coordination, (c) whether there are age-related differences in transfer effects. Twenty-three younger and 23 older adults were randomly assigned to dual-task training or control conditions. All participants were assessed before and after training on three dual-task transfer conditions; (1) stimulus modality transfer (2) response modality transfer (3) stimulus and response modalities transfer task. Training group showed larger improvement than the control group in the three transfer dual-task conditions, which suggests that training leads to more than specific learning of stimuli/response associations. Attentional costs analyses showed that training led to improved dual-task cost, only in conditions that involved new stimuli or response modalities, but not both. Moreover, training did not lead to a reduced task-set cost in the transfer conditions, which suggests some limitations in transfer effects that can be expected. Overall, the present study supports the notion that cognitive plasticity for attentional control is preserved in late adulthood. PMID:22629239

  4. Better dual-task processing in simultaneous interpreters

    PubMed Central

    Strobach, Tilo; Becker, Maxi; Schubert, Torsten; Kühn, Simone

    2015-01-01

    Simultaneous interpreting (SI) is a highly complex activity and requires the performance and coordination of multiple, simultaneous tasks: analysis and understanding of the discourse in a first language, reformulating linguistic material, storing of intermediate processing steps, and language production in a second language among others. It is, however, an open issue whether persons with experience in SI possess superior skills in coordination of multiple tasks and whether they are able to transfer these skills to lab-based dual-task situations. Within the present study, we set out to explore whether interpreting experience is associated with related higher-order executive functioning in the context of dual-task situations of the Psychological Refractory Period (PRP) type. In this PRP situation, we found faster reactions times in participants with experience in simultaneous interpretation in contrast to control participants without such experience. Thus, simultaneous interpreters possess superior skills in coordination of multiple tasks in lab-based dual-task situations. PMID:26528232

  5. Dual Motor-Cognitive Virtual Reality Training Impacts Dual-Task Performance in Freezing of Gait.

    PubMed

    Killane, Isabelle; Fearon, Conor; Newman, Louise; McDonnell, Conor; Waechter, Saskia M; Sons, Kristian; Lynch, Timothy; Reilly, Richard B

    2015-11-01

    Freezing of gait (FOG), an episodic gait disturbance characterized by the inability to generate effective stepping, occurs in more than half of Parkinson's disease patients. It is associated with both executive dysfunction and attention and becomes most evident during dual tasking (performing two tasks simultaneously). This study examined the effect of dual motor-cognitive virtual reality training on dual-task performance in FOG. Twenty community dwelling participants with Parkinson's disease (13 with FOG, 7 without FOG) participated in a pre-assessment, eight 20-minute intervention sessions, and a post-assessment. The intervention consisted of a virtual reality maze (DFKI, Germany) through which participants navigated by stepping-in-place on a balance board (Nintendo, Japan) under time pressure. This was combined with a cognitive task (Stroop test), which repeatedly divided participants' attention. The primary outcome measures were pre- and post-intervention differences in motor (stepping time, symmetry, rhythmicity) and cognitive (accuracy, reaction time) performance during single- and dual-tasks. Both assessments consisted of 1) a single cognitive task 2) a single motor task, and 3) a dual motor-cognitive task. Following the intervention, there was significant improvement in dual-task cognitive and motor parameters (stepping time and rhythmicity), dual-task effect for those with FOG and a noteworthy improvement in FOG episodes. These improvements were less significant for those without FOG. This is the first study to show benefit of a dual motor-cognitive approach on dual-task performance in FOG. Advances in such virtual reality interventions for home use could substantially improve the quality of life for patients who experience FOG. PMID:26394439

  6. TRANSFER EFFECTS IN TASK-SET COST AND DUAL-TASK COST AFTER DUAL-TASK TRAINING IN OLDER AND YOUNGER ADULTS: FURTHER EVIDENCE FOR COGNITIVE PLASTICITY IN ATTENTIONAL CONTROL IN LATE ADULTHOOD

    PubMed Central

    Bherer, Louis; Kramer, Arthur F.; Peterson, Matthew S.; Colcombe, Stanley; Erickson, Kirk; Becic, Ensar

    2010-01-01

    Older adults’ difficulties in performing two tasks concurrently have been well documented (Kramer & Madden, 2008). It has been observed that the age-related differences in dual-task performance are larger when the two tasks require similar motor responses (Hartley, 2001) and that in some conditions older adults also show greater susceptibility than younger adults to input interference (Hein & Schubert, 2004). The authors recently observed that even when the two tasks require motor responses, both older and younger adults can learn to perform a visual discrimination task and an auditory discrimination task faster and more accurately (Bherer et al., 2005). In the present study, the authors extended this finding to a dual-task condition that involves two visual tasks requiring two motor responses. Older and younger adults completed a dual-task training program in which continuous individualized adaptive feedback was provided to enhance performance. The results indicate that, even with similar motor responses and two visual stimuli, both older and younger adults showed substantial gains in performance after training and that the improvement generalized to new task combinations involving new stimuli. These results suggest that dual-task skills can be substantially improved in older adults and that cognitive plasticity in attentional control is still possible in old age. PMID:18568979

  7. Fine and gross motor skills: The effects on skill-focused dual-tasks.

    PubMed

    Raisbeck, Louisa D; Diekfuss, Jed A

    2015-10-01

    Dual-task methodology often directs participants' attention towards a gross motor skill involved in the execution of a skill, but researchers have not investigated the comparative effects of attention on fine motor skill tasks. Furthermore, there is limited information about participants' subjective perception of workload with respect to task performance. To examine this, the current study administered the NASA-Task Load Index following a simulated shooting dual-task. The task required participants to stand 15 feet from a projector screen which depicted virtual targets and fire a modified Glock 17 handgun equipped with an infrared laser. Participants performed the primary shooting task alone (control), or were also instructed to focus their attention on a gross motor skill relevant to task execution (gross skill-focused) and a fine motor skill relevant to task execution (fine skill-focused). Results revealed that workload was significantly greater during the fine skill-focused task for both skill levels, but performance was only affected for the lesser-skilled participants. Shooting performance for the lesser-skilled participants was greater during the gross skill-focused condition compared to the fine skill-focused condition. Correlational analyses also demonstrated a significant negative relationship between shooting performance and workload during the gross skill-focused task for the higher-skilled participants. A discussion of the relationship between skill type, workload, skill level, and performance in dual-task paradigms is presented.

  8. On the importance of Task 1 and error performance measures in PRP dual-task studies

    PubMed Central

    Strobach, Tilo; Schütz, Anja; Schubert, Torsten

    2015-01-01

    The psychological refractory period (PRP) paradigm is a dominant research tool in the literature on dual-task performance. In this paradigm a first and second component task (i.e., Task 1 and Task 2) are presented with variable stimulus onset asynchronies (SOAs) and priority to perform Task 1. The main indicator of dual-task impairment in PRP situations is an increasing Task 2-RT with decreasing SOAs. This impairment is typically explained with some task components being processed strictly sequentially in the context of the prominent central bottleneck theory. This assumption could implicitly suggest that processes of Task 1 are unaffected by Task 2 and bottleneck processing, i.e., decreasing SOAs do not increase reaction times (RTs) and error rates of the first task. The aim of the present review is to assess whether PRP dual-task studies included both RT and error data presentations and statistical analyses and whether studies including both data types (i.e., RTs and error rates) show data consistent with this assumption (i.e., decreasing SOAs and unaffected RTs and/or error rates in Task 1). This review demonstrates that, in contrast to RT presentations and analyses, error data is underrepresented in a substantial number of studies. Furthermore, a substantial number of studies with RT and error data showed a statistically significant impairment of Task 1 performance with decreasing SOA. Thus, these studies produced data that is not primarily consistent with the strong assumption that processes of Task 1 are unaffected by Task 2 and bottleneck processing in the context of PRP dual-task situations; this calls for a more careful report and analysis of Task 1 performance in PRP studies and for a more careful consideration of theories proposing additions to the bottleneck assumption, which are sufficiently general to explain Task 1 and Task 2 effects. PMID:25904890

  9. Dual task interference during walking: The effects of texting on situational awareness and gait stability.

    PubMed

    Lim, Jongil; Amado, Avelino; Sheehan, Leo; Van Emmerik, Richard E A

    2015-10-01

    Dual-task interference caused by mobile phone use while walking increases safety risks by increasing attentional and cognitive demands. Situational awareness, important for control of walking and safety, has been examined previously but measured only by the awareness of visually noteworthy objects in the environment or the number of times the person looked up from the phone. This study systematically investigated the effects of texting on situational awareness to different environments and its consequent impact on gait kinematics. Twenty healthy volunteers walked on a treadmill while texting and attending to visual tasks simultaneously. Gait parameters and situational awareness examined under dual-task conditions (walk and text or walk, text, and visual task) were compared with those of single-task conditions (text, walk or visual task only). The size of the visual field, display duration of the visual cue, and visual acuity demand were varied across the visual task conditions. About half of the visual cues provided during walking and texting were not perceived (48.3%) as compared to the visual task only condition. The magnitude of this loss of situational awareness was dependent upon the nature of visual information provided. While gait parameters were not different among visual task conditions, greater total medial-lateral excursion of the pelvis was observed in the walk and text condition compared to the walk only condition, showing the dual-task effects of texting on gait kinematics. The study provides further evidence of dual-task effects of texting on situational awareness as well as gait kinematics.

  10. Dual task effects for asymmetric stepping on a split-belt treadmill.

    PubMed

    McFadyen, Bradford J; Hegeman, Judith; Duysens, Jacques

    2009-10-01

    Bilaterally asymmetric stepping during walking is common to a number of pathological gaits (e.g., hemiplegia, limping). In the present work, the attention level of asymmetric stepping was studied by having subjects walk on a split-belt treadmill with symmetric (2 km/h) and asymmetric (2 km/h vs 4 km/h and 2 km/h vs 6 km/h) belt speeds both with and without a dual auditory Stroop task. There was no significant change in response reaction times across walking conditions or between walking and standing. The proportion of stance phase was unchanged by the dual task during symmetric walking. Stance phase proportions, however, significantly increased during dual tasking for the limb on the faster belt for both asymmetric conditions, while they decreased for the limb on the slower belt for the most asymmetric condition. There were also small modifications to double support proportions and a main effect of dual tasking to double support proportion variability. Observed dual task changes showed interference by the cognitive task with asymmetric gait performance, suggesting that asymmetric stepping, such as seen in limping gaits, requires more attention than symmetric walking. Such attention may, in part, be due to the dynamic balance required in asymmetric limb loading and unloading. PMID:19595592

  11. The source of dual-task limitations: Serial or parallel processing of multiple response selections?

    PubMed Central

    Marois, René

    2014-01-01

    Although it is generally recognized that the concurrent performance of two tasks incurs costs, the sources of these dual-task costs remain controversial. The serial bottleneck model suggests that serial postponement of task performance in dual-task conditions results from a central stage of response selection that can only process one task at a time. Cognitive-control models, by contrast, propose that multiple response selections can proceed in parallel, but that serial processing of task performance is predominantly adopted because its processing efficiency is higher than that of parallel processing. In the present study, we empirically tested this proposition by examining whether parallel processing would occur when it was more efficient and financially rewarded. The results indicated that even when parallel processing was more efficient and was incentivized by financial reward, participants still failed to process tasks in parallel. We conclude that central information processing is limited by a serial bottleneck. PMID:23864266

  12. Effects of aging and dual tasking on step adjustments to perturbations in visually cued walking.

    PubMed

    Mazaheri, Masood; Hoogkamer, Wouter; Potocanac, Zrinka; Verschueren, Sabine; Roerdink, Melvyn; Beek, Peter J; Peper, C E; Duysens, Jacques

    2015-12-01

    Making step adjustments is an essential component of walking. However, the ability to make step adjustments may be compromised when the walker's attentional capacity is limited. This study compared the effects of aging and dual tasking on step adjustments in response to stepping-target perturbations during visually cued treadmill walking. Fifteen older adults (69.4 ± 5.0 years; mean ± SD) and fifteen young adults (25.4 ± 3.0 years) walked at a speed of 3 km/h on a treadmill. Both groups performed visually cued step adjustments in response to unpredictable shifts of projected stepping targets in forward (FW), backward (BW) or sideward (SW) directions, at different levels of task difficulty [which increased as the available response distance (ARD) decreased], and with and without dual tasking (auditory Stroop task). In both groups, step adjustments were smaller than required. For FW and BW shifts, older adults undershot more under dual-task conditions. For these shifts, ARD affected the age groups differentially. For SW shifts, larger errors were found for older adults, dual tasking and the most difficult ARD. Stroop task performance did not differ between groups in all conditions. Older adults have more difficulty than young adults to make corrective step adjustments while walking, especially under dual-tasking conditions. Furthermore, they seemed to prioritize the cognitive task over the step adjustment task, a strategy that may pose aging populations at a greater fall risk. For comparable task difficulty, the older adults performed considerably worse than the young adults, indicating a decreased ability to adjust steps under time pressure.

  13. Effects of aging and dual tasking on step adjustments to perturbations in visually cued walking.

    PubMed

    Mazaheri, Masood; Hoogkamer, Wouter; Potocanac, Zrinka; Verschueren, Sabine; Roerdink, Melvyn; Beek, Peter J; Peper, C E; Duysens, Jacques

    2015-12-01

    Making step adjustments is an essential component of walking. However, the ability to make step adjustments may be compromised when the walker's attentional capacity is limited. This study compared the effects of aging and dual tasking on step adjustments in response to stepping-target perturbations during visually cued treadmill walking. Fifteen older adults (69.4 ± 5.0 years; mean ± SD) and fifteen young adults (25.4 ± 3.0 years) walked at a speed of 3 km/h on a treadmill. Both groups performed visually cued step adjustments in response to unpredictable shifts of projected stepping targets in forward (FW), backward (BW) or sideward (SW) directions, at different levels of task difficulty [which increased as the available response distance (ARD) decreased], and with and without dual tasking (auditory Stroop task). In both groups, step adjustments were smaller than required. For FW and BW shifts, older adults undershot more under dual-task conditions. For these shifts, ARD affected the age groups differentially. For SW shifts, larger errors were found for older adults, dual tasking and the most difficult ARD. Stroop task performance did not differ between groups in all conditions. Older adults have more difficulty than young adults to make corrective step adjustments while walking, especially under dual-tasking conditions. Furthermore, they seemed to prioritize the cognitive task over the step adjustment task, a strategy that may pose aging populations at a greater fall risk. For comparable task difficulty, the older adults performed considerably worse than the young adults, indicating a decreased ability to adjust steps under time pressure. PMID:26298043

  14. Word Effects in Dual-Task Studies Using Lexical Decision and Naming as Task 2

    NASA Technical Reports Server (NTRS)

    Remington, Roger; McCann, Robert S.; VanSelst, Mark; Shafto, Michael (Technical Monitor)

    1997-01-01

    Word frequency effects in dual-task, lexical decision are variously reported to be additive or under-additive across SOA. We replicate and extend earlier lexical decision studies and find word frequency to be additive across SOA. To more directly capture lexical processing, we examine dual-task naming. Once again we find word frequency to be additive across SOA. Lexical processing appears to be constrained by central processing limitations.

  15. Word Frequency Effects in Dual-Task Studies Using Lexical Decision and Naming as Task 2

    NASA Technical Reports Server (NTRS)

    Remington, Roger W.; McCann, Robert S.; VanSelst, Mark; Shafto, Michael G. (Technical Monitor)

    1997-01-01

    Word frequency effects in dual-task lexical decision are variously reported to be additive or underadditive across SOA. We replicate and extend earlier lexical decision studies and find word frequency to be additive across SOA. To more directly capture lexical processing, we examine dual-task naming. Once again, we find word frequency to be additive across SOA. Lexical processing appears to be constrained by central processing limitations.

  16. Building a framework for a dual task taxonomy.

    PubMed

    McIsaac, Tara L; Lamberg, Eric M; Muratori, Lisa M

    2015-01-01

    The study of dual task interference has gained increasing attention in the literature for the past 35 years, with six MEDLINE citations in 1979 growing to 351 citations indexed in 2014 and a peak of 454 cited papers in 2013. Increasingly, researchers are examining dual task cost in individuals with pathology, including those with neurodegenerative diseases. While the influence of these papers has extended from the laboratory to the clinic, the field has evolved without clear definitions of commonly used terms and with extreme variations in experimental procedures. As a result, it is difficult to examine the interference literature as a single body of work. In this paper we present a new taxonomy for classifying cognitive-motor and motor-motor interference within the study of dual task behaviors that connects traditional concepts of learning and principles of motor control with current issues of multitasking analysis. As a first step in the process we provide an operational definition of dual task, distinguishing it from a complex single task. We present this new taxonomy, inclusive of both cognitive and motor modalities, as a working model; one that we hope will generate discussion and create a framework from which one can view previous studies and develop questions of interest. PMID:25961027

  17. Building a framework for a dual task taxonomy.

    PubMed

    McIsaac, Tara L; Lamberg, Eric M; Muratori, Lisa M

    2015-01-01

    The study of dual task interference has gained increasing attention in the literature for the past 35 years, with six MEDLINE citations in 1979 growing to 351 citations indexed in 2014 and a peak of 454 cited papers in 2013. Increasingly, researchers are examining dual task cost in individuals with pathology, including those with neurodegenerative diseases. While the influence of these papers has extended from the laboratory to the clinic, the field has evolved without clear definitions of commonly used terms and with extreme variations in experimental procedures. As a result, it is difficult to examine the interference literature as a single body of work. In this paper we present a new taxonomy for classifying cognitive-motor and motor-motor interference within the study of dual task behaviors that connects traditional concepts of learning and principles of motor control with current issues of multitasking analysis. As a first step in the process we provide an operational definition of dual task, distinguishing it from a complex single task. We present this new taxonomy, inclusive of both cognitive and motor modalities, as a working model; one that we hope will generate discussion and create a framework from which one can view previous studies and develop questions of interest.

  18. Neural Correlates of Dual-Task Walking: Effects of Cognitive versus Motor Interference in Young Adults

    PubMed Central

    Beurskens, Rainer; Steinberg, Fabian; Antoniewicz, Franziska; Wolff, Wanja; Granacher, Urs

    2016-01-01

    Walking while concurrently performing cognitive and/or motor interference tasks is the norm rather than the exception during everyday life and there is evidence from behavioral studies that it negatively affects human locomotion. However, there is hardly any information available regarding the underlying neural correlates of single- and dual-task walking. We had 12 young adults (23.8 ± 2.8 years) walk while concurrently performing a cognitive interference (CI) or a motor interference (MI) task. Simultaneously, neural activation in frontal, central, and parietal brain areas was registered using a mobile EEG system. Results showed that the MI task but not the CI task affected walking performance in terms of significantly decreased gait velocity and stride length and significantly increased stride time and tempo-spatial variability. Average activity in alpha and beta frequencies was significantly modulated during both CI and MI walking conditions in frontal and central brain regions, indicating an increased cognitive load during dual-task walking. Our results suggest that impaired motor performance during dual-task walking is mirrored in neural activation patterns of the brain. This finding is in line with established cognitive theories arguing that dual-task situations overstrain cognitive capabilities resulting in motor performance decrements. PMID:27200192

  19. Upper-Extremity Dual-Task Function: An Innovative Method to Assess Cognitive Impairment in Older Adults

    PubMed Central

    Toosizadeh, Nima; Najafi, Bijan; Reiman, Eric M.; Mager, Reine M.; Veldhuizen, Jaimeson K.; O’Connor, Kathy; Zamrini, Edward; Mohler, Jane

    2016-01-01

    Background: Difficulties in orchestrating simultaneous tasks (i.e., dual-tasking) have been associated with cognitive impairments in older adults. Gait tests have been commonly used as the motor task component for dual-task assessments; however, many older adults have mobility impairments or there is a lack of space in busy clinical settings. We assessed an upper-extremity function (UEF) test as an alternative motor task to study the dual-task motor performance in older adults. Methods: Older adults (≥65 years) were recruited, and cognitive ability was measured using the Montreal cognitive assessment (MoCA). Participants performed repetitive elbow flexion with their maximum pace, once single-task, and once while counting backward by one (dual-task). Single- and dual-task gait tests were also performed with normal speed. Three-dimensional kinematics was measured both from upper-extremity and lower-extremity using wearable sensors to determine UEF and gait parameters. Parameters were compared between the cognitively impaired and healthy groups using analysis of variance tests, while controlling for age, gender, and body mass index (BMI). Correlations between UEF and gait parameters for dual-task and dual-task cost were assessed using linear regression models. Results: Sixty-seven older adults were recruited (age = 83 ± 10 years). Based on MoCA, 10 (15%) were cognitively impaired. While no significant differences were observed in the single-task condition, within the dual-task condition, the cognitively impaired group showed significantly less arm flexion speed (62%, d = 1.51, p = 0.02) and range of motion (27%, d = 0.93, p = 0.04), and higher speed variability (88%, d = 1.82, p < 0.0001) compared to the cognitively intact group, when adjusted with age, gender, and BMI. Significant correlations were observed between UEF speed parameters and gait stride velocity for dual-task condition (r = 0.55, p < 0.0001) and dual-task cost (r = 0.28, p = 0.03). Conclusion: We

  20. Short-term memory and dual task performance

    NASA Technical Reports Server (NTRS)

    Regan, J. E.

    1982-01-01

    Two hypotheses concerning the way in which short-term memory interacts with another task in a dual task situation are considered. It is noted that when two tasks are combined, the activity of controlling and organizing performance on both tasks simultaneously may compete with either task for a resource; this resource may be space in a central mechanism or general processing capacity or it may be some task-specific resource. If a special relationship exists between short-term memory and control, especially if there is an identity relationship between short-term and a central controlling mechanism, then short-term memory performance should show a decrement in a dual task situation. Even if short-term memory does not have any particular identity with a controlling mechanism, but both tasks draw on some common resource or resources, then a tradeoff between the two tasks in allocating resources is possible and could be reflected in performance. The persistent concurrence cost in memory performance in these experiments suggests that short-term memory may have a unique status in the information processing system.

  1. Mood states determine the degree of task shielding in dual-task performance.

    PubMed

    Zwosta, Katharina; Hommel, Bernhard; Goschke, Thomas; Fischer, Rico

    2013-01-01

    Current models of multitasking assume that dual-task performance and the degree of multitasking are affected by cognitive control strategies. In particular, cognitive control is assumed to regulate the amount of shielding of the prioritised task from crosstalk from the secondary task. We investigated whether and how task shielding is influenced by mood states. Participants were exposed to two short film clips, one inducing high and one inducing low arousal, of either negative or positive content. Negative mood led to stronger shielding of the prioritised task (i.e., less crosstalk) than positive mood, irrespective of arousal. These findings support the assumption that emotional states determine the parameters of cognitive control and play an important role in regulating dual-task performance.

  2. Dual-task interference with equal task emphasis: graded capacity sharing or central postponement?

    NASA Technical Reports Server (NTRS)

    Ruthruff, Eric; Pashler, Harold E.; Hazeltine, Eliot

    2003-01-01

    Most studies using the psychological refractory period (PRP) design suggest that dual-task performance is limited by a central bottleneck. Because subjects are usually told to emphasize Task 1, however, the bottleneck might reflect a strategic choice rather than a structural limitation. To evaluate the possibility that central operations can proceed in parallel, albeit with capacity limitations, we conducted two dual-task experiments with equal task emphasis. In both experiments, subjects tended to either group responses together or respond to one task well before the other. In addition, stimulus-response compatibility effects were roughly constant across stimulus onset asynchronies (SOAs). At the short SOA, compatibility effects also carried over onto response times for the other task. This pattern of results is difficult to reconcile with the possibility that subjects share capacity roughly equally between simultaneous central operations. However, this pattern is consistent with the existence of a structural central bottleneck.

  3. Characterization of cognitive and motor performance during dual-tasking in healthy older adults and patients with Parkinson's disease.

    PubMed

    Wild, Lucia Bartmann; de Lima, Daiane Borba; Balardin, Joana Bisol; Rizzi, Luana; Giacobbo, Bruno Lima; Oliveira, Henrique Bianchi; de Lima Argimon, Irani Iracema; Peyré-Tartaruga, Leonardo Alexandre; Rieder, Carlos R M; Bromberg, Elke

    2013-02-01

    The primary purpose of this study was to investigate the effect of dual-tasking on cognitive performance and gait parameters in patients with idiopathic Parkinson's disease (PD) without dementia. The impact of cognitive task complexity on cognition and walking was also examined. Eighteen patients with PD (ages 53-88, 10 women; Hoehn and Yahr stage I-II) and 18 older adults (ages 61-84; 10 women) completed two neuropsychological measures of executive function/attention (the Stroop Test and Wisconsin Card Sorting Test). Cognitive performance and gait parameters related to functional mobility of stride were measured under single (cognitive task only) and dual-task (cognitive task during walking) conditions with different levels of difficulty and different types of stimuli. In addition, dual-task cognitive costs were calculated. Although cognitive performance showed no significant difference between controls and PD patients during single or dual-tasking conditions, only the patients had a decrease in cognitive performance during walking. Gait parameters of patients differed significantly from controls at single and dual-task conditions, indicating that patients gave priority to gait while cognitive performance suffered. Dual-task cognitive costs of patients increased with task complexity, reaching significantly higher values then controls in the arithmetic task, which was correlated with scores on executive function/attention (Stroop Color-Word Page). Baseline motor functioning and task executive/attentional load affect the performance of cognitive tasks of PD patients while walking. These findings provide insight into the functional strategies used by PD patients in the initial phases of the disease to manage dual-task interference. PMID:23052601

  4. The effects of stimulus modality and task integrality: Predicting dual-task performance and workload from single-task levels

    NASA Technical Reports Server (NTRS)

    Hart, S. G.; Shively, R. J.; Vidulich, M. A.; Miller, R. C.

    1986-01-01

    The influence of stimulus modality and task difficulty on workload and performance was investigated. The goal was to quantify the cost (in terms of response time and experienced workload) incurred when essentially serial task components shared common elements (e.g., the response to one initiated the other) which could be accomplished in parallel. The experimental tasks were based on the Fittsberg paradigm; the solution to a SternBERG-type memory task determines which of two identical FITTS targets are acquired. Previous research suggested that such functionally integrated dual tasks are performed with substantially less workload and faster response times than would be predicted by suming single-task components when both are presented in the same stimulus modality (visual). The physical integration of task elements was varied (although their functional relationship remained the same) to determine whether dual-task facilitation would persist if task components were presented in different sensory modalities. Again, it was found that the cost of performing the two-stage task was considerably less than the sum of component single-task levels when both were presented visually. Less facilitation was found when task elements were presented in different sensory modalities. These results suggest the importance of distinguishing between concurrent tasks that complete for limited resources from those that beneficially share common resources when selecting the stimulus modalities for information displays.

  5. Measuring listening effort: driving simulator vs. simple dual-task paradigm

    PubMed Central

    Wu, Yu-Hsiang; Aksan, Nazan; Rizzo, Matthew; Stangl, Elizabeth; Zhang, Xuyang; Bentler, Ruth

    2014-01-01

    Objectives The dual-task paradigm has been widely used to measure listening effort. The primary objectives of the study were to (1) investigate the effect of hearing aid amplification and a hearing aid directional technology on listening effort measured by a complicated, more real world dual-task paradigm, and (2) compare the results obtained with this paradigm to a simpler laboratory-style dual-task paradigm. Design The listening effort of adults with hearing impairment was measured using two dual-task paradigms, wherein participants performed a speech recognition task simultaneously with either a driving task in a simulator or a visual reaction-time task in a sound-treated booth. The speech materials and road noises for the speech recognition task were recorded in a van traveling on the highway in three hearing aid conditions: unaided, aided with omni directional processing (OMNI), and aided with directional processing (DIR). The change in the driving task or the visual reaction-time task performance across the conditions quantified the change in listening effort. Results Compared to the driving-only condition, driving performance declined significantly with the addition of the speech recognition task. Although the speech recognition score was higher in the OMNI and DIR conditions than in the unaided condition, driving performance was similar across these three conditions, suggesting that listening effort was not affected by amplification and directional processing. Results from the simple dual-task paradigm showed a similar trend: hearing aid technologies improved speech recognition performance, but did not affect performance in the visual reaction-time task (i.e., reduce listening effort). The correlation between listening effort measured using the driving paradigm and the visual reaction-time task paradigm was significant. The finding showing that our older (56 to 85 years old) participants’ better speech recognition performance did not result in reduced

  6. Dual-task performance under acute stress in female adolescents with borderline personality disorder.

    PubMed

    Kaess, Michael; Parzer, Peter; Koenig, Julian; Resch, Franz; Brunner, Romuald

    2016-09-01

    Research to elucidate early alterations of higher cognitive processes in adolescents with BPD is rare. This study investigated differences in dual-task performance in adolescents with BPD during stress and non-stress conditions. The study sample comprised 30 female adolescents with BPD and 34 healthy controls. The impact of stress on dual-task performance was measured using a standardized stressor. Self-reports of distress and measures of heart rate (HR) were obtained to measure stress reactivity. There were no group differences in task performance. Under stress conditions, the performance on the auditory task decreased in both groups but without significant group differences. Healthy controls showed an increase of mean HR after stress induction compared to no change in the BPD group. The finding of attenuated HR response to acute stress in adolescent patients with BPD may contradict current theories that the affective hyperresponsivity in BPD is based on a biologically determined mechanism. PMID:26852226

  7. Gait in Very Preterm School-Aged Children in Dual-Task Paradigms

    PubMed Central

    Hagmann-von Arx, Priska; Manicolo, Olivia; Perkinson-Gloor, Nadine; Weber, Peter; Grob, Alexander; Lemola, Sakari

    2015-01-01

    Objective The control of gait requires executive and attentional functions. As preterm children show executive and attentional deficits compared to full-term children, performing concurrent tasks that impose additional cognitive load may lead to poorer walking performance in preterm compared to full-term children. Knowledge regarding gait in preterm children after early childhood is scarce. We examined straight walking and if it is more affected in very preterm than in full-term children in dual-task paradigms. Study design Twenty preterm children with very low birth-weight (≤ 1500 g), 24 preterm children with birth-weight > 1500 g, and 44 full-term children, born between 2001 and 2006, were investigated. Gait was assessed using an electronic walkway system (GAITRite) while walking without a concurrent task (single-task) and while performing one concurrent (dual-task) or two concurrent (triple-task) tasks. Spatio-temporal gait parameters (gait velocity, cadence, stride length, single support time, double support time), normalized gait parameters (normalized velocity, normalized cadence, normalized stride length) and gait variability parameters (stride velocity variability, stride length variability) were analyzed. Results In dual- and triple-task conditions children showed decreased gait velocity, cadence, stride length, as well as increased single support time, double support time and gait variability compared to single-task walking. Further, results showed systematic decreases in stride velocity variability from preterm children with very low birth weight (≤ 1500 g) to preterm children with birth weight > 1500 g to full-term children. There were no significant interactions between walking conditions and prematurity status. Conclusions Dual and triple tasking affects gait of preterm and full-term children, confirming previous results that walking requires executive and attentional functions. Birth-weight dependent systematic changes in stride velocity

  8. Information access in a dual-task context: testing a model of optimal strategy selection

    NASA Technical Reports Server (NTRS)

    Wickens, C. D.; Seidler, K. S.

    1997-01-01

    Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.

  9. Age-related deficits of dual-task walking: the role of foot vision.

    PubMed

    Bock, Otmar; Beurskens, Rainer

    2011-02-01

    Previous studies found that age-related deficits of dual-task walking emerge with secondary tasks that require substantial visual processing, but are absent with tasks that require little or no visual processing. We evaluated whether this is so because visual tasks typically interfere with foot vision, on which older persons depend more heavily than young ones. Young (25±3 years) and older (69±5 years) subjects walked along a straight path and checked boxes on a handheld panel, separately or concurrently. The panel was either transparent or opaque, thus allowing or blocking vision of the feet, respectively. We quantified subjects' performance by spatial and temporal gait measures, and as the speed of checking. An analysis of variance revealed significant effects of age and of condition (single, dual) for several gait measures, as well as for checking speed. The dual-task costs (ǀdual-singleǀ/single) averaged 0.04±0.14 in younger and 0.33±0.30 in older subjects; this age difference was significant in a t-test (p<0.01). Most importantly, performance measures obtained with the transparent and with the opaque panel were not significantly different. In conclusion, our study confirms previous findings about age-related deficits of walking with a concurrent visual task, documents for the first time that these deficits influence the entire spatio-temporal gait structure, but provides no support for the notion that they reflect an increased dependence on foot vision.

  10. Is dual-task performance necessarily impaired in space?

    PubMed

    Fowler, B; Bock, O; Comfort, D

    2000-01-01

    Recent single-subject experiments in space have reported impaired dual-task performance that could result from either a direct effect of microgravity on the central nervous system or from the multistressor environment. We sought to distinguish between these hypotheses using 6 astronauts in the 16-day NASA Neurolab mission, testing them at intervals with a dual task consisting of primary pursuit tracking without vision of the hand and secondary reaction time (RT). The participants were highly trained, instructed to maintain a fixed attention strategy, and restrained in the apparatus. The results showed that absolute and variable tracking error, as well as correct RT and the standard deviation of RT, were unimpaired. However, RT errors became more variable, an effect attributed to a decrease in strategic control. We conclude that the impairments observed in previous dual-task space experiments can be attributed to stressors rather than to microgravity and that performance deficits are probably not a necessary concomitant of space flight if attention is paid to task design and astronaut training.

  11. Using dual-task methodology to dissociate automatic from nonautomatic processes involved in artificial grammar learning.

    PubMed

    Hendricks, Michelle A; Conway, Christopher M; Kellogg, Ronald T

    2013-09-01

    Previous studies have suggested that both automatic and intentional processes contribute to the learning of grammar and fragment knowledge in artificial grammar learning (AGL) tasks. To explore the relative contribution of automatic and intentional processes to knowledge gained in AGL, we utilized dual-task methodology to dissociate automatic and intentional grammar- and fragment-based knowledge in AGL at both acquisition and at test. Both experiments used a balanced chunk strength grammar to assure an equal proportion of fragment cues (i.e., chunks) in grammatical and nongrammatical test items. In Experiment 1, participants engaged in a working memory dual-task either during acquisition, test, or both acquisition and test. The results showed that participants performing the dual-task during acquisition learned the artificial grammar as well as the single-task group, presumably by relying on automatic learning mechanisms. A working memory dual-task at test resulted in attenuated grammar performance, suggesting a role for intentional processes for the expression of grammatical learning at test. Experiment 2 explored the importance of perceptual cues by changing letters between the acquisition and test phase; unlike Experiment 1, there was no significant learning of grammatical information for participants under dual-task conditions in Experiment 2, suggesting that intentional processing is necessary for successful acquisition and expression of grammar-based knowledge under transfer conditions. In sum, it appears that some aspects of learning in AGL are indeed relatively automatic, although the expression of grammatical information and the learning of grammatical patterns when perceptual similarity is eliminated both appear to require explicit resources.

  12. The association between media multitasking, task-switching, and dual-task performance.

    PubMed

    Alzahabi, Reem; Becker, Mark W

    2013-10-01

    The recent rise in media use has prompted researchers to investigate its influence on users' basic cognitive processes, such as attention and cognitive control. However, most of these investigations have failed to consider that the rise in media use has been accompanied by an even more dramatic rise in media multitasking (engaging with multiple forms of media simultaneously). Here we investigate how one's ability to switch between 2 tasks and to perform 2 tasks simultaneously is associated with media multitasking experience. Participants saw displays comprised of a number-letter pair and classified the number as odd or even and/or the letter as a consonant or vowel. In task-switching blocks, a cue indicated which classification to perform on each trial. In dual-task blocks, participants performed both classifications. Heavy and light media multitaskers showed comparable performance in the dual-task. Across 2 experiments, heavy media multitaskers were better able to switch between tasks in the task-switching paradigm. Thus, while media multitasking was not associated with increased ability to process 2 tasks in parallel, it was associated with an increased ability to shift between discrete tasks.

  13. Using dual tasks to test immediate transfer of training between naturalistic movements: A proof-of-principle study

    PubMed Central

    Schaefer, Sydney Y.; Lang, Catherine E.

    2012-01-01

    Theories of motor learning predict that training a movement reduces the amount of attention needed for its performance (i.e. more automatic). If training one movement transfers, then the amount of attention needed for performing a second movement should also be reduced, as measured under dual task conditions. The purpose of this study was to test whether dual task paradigms are feasible for detecting transfer of training between two naturalistic movements. Immediately following motor training, subjects improved performance of a second untrained movement under both single and dual task conditions. Subjects with no training did not. Improved performance in the untrained movement was likely due to transfer, and suggests that dual tasks may be feasible for detecting transfer between naturalistic actions. PMID:22934682

  14. Motor-Cognitive Dual-Task Training in Neurologic Disorders: A Systematic Review

    PubMed Central

    Fritz, NE; Cheek, FM; Nichols-Larsen, DS

    2015-01-01

    Background and Purpose Deficits in motor-cognitive dual-tasks (e.g., walking while talking) are common in individuals with neurological conditions. This review was conducted to determine the effectiveness of motor-cognitive dual-task training (DTT) compared to usual care on mobility and cognition in individuals with neurologic disorders. Methods Databases searched were Biosis, CINAHL, ERIC, PsychInfo, EBSCO Psychological & Behavioral, PubMed, Scopus, and Web of Knowledge. Eligibility criteria were studies of adults with neurologic disorders that included DTT and outcomes of gait or balance were included. Fourteen studies met inclusion criteria. Participants were individuals with brain injury, Parkinson’s disease (PD) and Alzheimer’s disease (AD). Intervention protocols included cued walking, cognitive tasks paired with gait, balance, and strength training and virtual reality or gaming. Quality of the included trials was evaluated with a standardized rating scale of clinical relevance. Results Results show that DTT improves single-task gait velocity and stride length in PD and AD, dual-task gait velocity and stride length in PD, AD and brain injury, and may improve balance and cognition in PD and AD. The inclusion criteria limited the diagnostic groups included. Discussion and Conclusions The range of training protocols and outcome assessments in available studies limited comparison of the results across studies. Improvement of dual-task ability in individuals with neurologic disorders holds potential for improving gait, balance and cognition. Motor-cognitive dual-task deficits in individuals with neurologic disorders may be amenable to training. Video Abstract available for additional insights from the authors (See Supplemental Digital Content). PMID:26079569

  15. The effects of voice and manual control mode on dual task performance

    NASA Technical Reports Server (NTRS)

    Wickens, C. D.; Zenyuh, J.; Culp, V.; Marshak, W.

    1986-01-01

    Two fundamental principles of human performance, compatibility and resource competition, are combined with two structural dichotomies in the human information processing system, manual versus voice output, and left versus right cerebral hemisphere, in order to predict the optimum combination of voice and manual control with either hand, for time-sharing performance of a dicrete and continuous task. Eight right handed male subjected performed a discrete first-order tracking task, time-shared with an auditorily presented Sternberg Memory Search Task. Each task could be controlled by voice, or by the left or right hand, in all possible combinations except for a dual voice mode. When performance was analyzed in terms of a dual-task decrement from single task control conditions, the following variables influenced time-sharing efficiency in diminishing order of magnitude, (1) the modality of control, (discrete manual control of tracking was superior to discrete voice control of tracking and the converse was true with the memory search task), (2) response competition, (performance was degraded when both tasks were responded manually), (3) hemispheric competition, (performance degraded whenever two tasks were controlled by the left hemisphere) (i.e., voice or right handed control). The results confirm the value of predictive models invoice control implementation.

  16. Expertise, attention, and memory in sensorimotor skill execution: impact of novel task constraints on dual-task performance and episodic memory.

    PubMed

    Beilock, Sian L; Wierenga, Sarah A; Carr, Thomas H

    2002-10-01

    Two experiments explored the attention and memory processes governing sensorimotor skill. Experiment 1 compared novice and experienced golf putting performance in single-task (putting in isolation) and dual-task conditions (putting while performing an auditory word search task). At specific intervals, participants also produced episodic descriptions of specific putts. Experiment 2 assessed novice performance following training on the same putting task. In Experiment 1, experienced golfers did not differ in putting accuracy from single-to dual-task conditions and, compared to novices, had higher recognition memory for words heard while putting but diminished episodic memories of specific putts. However, when using an s-shaped arbitrarily weighted "funny putter" designed to disrupt the mechanics of skill execution, experienced golfers produced extensive episodic memories of specific putts but showed decreased dual-task putting accuracy and recognition memory for secondary task words. Trained novices produced results intermediate between the untrained novices and experienced golfers. As predicted by current theories of practice-based automaticity, expertise leads to proceduralized control that does not require constant attention. Resources are free to devote to secondary task demands, yet episodic memory for primary task performance is impoverished. Novel task constraints (e.g., a funny putter) increase attention to execution, compromising secondary task performance but enhancing memory for skill execution. PMID:12420993

  17. Do small dual-task costs reflect ideomotor compatibility or the absence of crosstalk?

    PubMed

    Halvorson, Kimberly M; Hazeltine, Eliot

    2015-10-01

    Dual-task costs can be greatly reduced or even eliminated when both tasks use highly-compatible S-R associations. According to Greenwald (Journal of Experimental Psychology: Human Perception and Performance, 30, 632-636, 2003), this occurs because the appropriate response can be accessed without engaging performance-limiting response selection processes, a proposal consistent with the embodied cognition framework in that it suggests that stimuli can automatically activate motor codes (e.g., Pezzulo et al., New Ideas in Psychology, 31(3), 270-290, 2013). To test this account, we reversed the stimulus-response mappings for one or both tasks so that some participants had to "do the opposite" of what they perceived. In these reversed conditions, stimuli resembled the environmental outcome of the alternative (incorrect) response. Nonetheless, reversed tasks were performed without costs even when paired with an unreversed task. This finding suggests that the separation of the central codes across tasks (e.g., Wickens, 1984) is more critical than the specific S-R relationships; dual-task costs can be avoided when the tasks engage distinct modality-based systems. PMID:25754530

  18. The Effect of Cognitive-Task Type and Walking Speed on Dual-Task Gait in Healthy Adults.

    PubMed

    Wrightson, James G; Ross, Emma Z; Smeeton, Nicholas J

    2016-01-01

    In a number of studies in which a dual-task gait paradigm was used, researchers reported a relationship between cognitive function and gait. However, it is not clear to what extent these effects are dependent on the type of cognitive and walking tasks used in the dual-task paradigm. This study examined whether stride-time variability (STV) and trunk range of motion (RoM) are affected by the type of cognitive task and walking speed used during dual-task gait. Participants walked at both their preferred walking speed and at 25% of their preferred walking speed and performed a serial subtraction and a working memory task at both speeds. Although both tasks significantly reduced STV at both walking speeds, there was no difference between the two tasks. Trunk RoM was affected by the walking speed and type of cognitive task used during dual-task gait: Mediolateral trunk RoM was increased at the slow walking speed, and anterior-posterior trunk RoM was higher only when performing the serial subtraction task at the slow walking speed. The reduction of STV, regardless of cognitive-task type, suggests that healthy adults may redirect cognitive processes away from gait toward cognitive-task performance during dual-task gait. PMID:25823560

  19. Musical training, bilingualism, and executive function: a closer look at task switching and dual-task performance.

    PubMed

    Moradzadeh, Linda; Blumenthal, Galit; Wiseheart, Melody

    2015-07-01

    This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual-task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non-musician, or monolingual non-musician) were matched on age and socioeconomic status and administered task switching and dual-task paradigms. Results demonstrated reduced global and local switch costs in musicians compared with non-musicians, suggesting that musical training can contribute to increased efficiency in the ability to shift flexibly between mental sets. On dual-task performance, musicians also outperformed non-musicians. There was neither a cognitive advantage for bilinguals relative to monolinguals, nor an interaction between music and language to suggest additive effects of both types of experience. These findings demonstrate that long-term musical training is associated with improvements in task switching and dual-task performance.

  20. The effects on dynamic balance of dual-tasking using smartphone functions.

    PubMed

    Hyong, In Hyouk

    2015-02-01

    [Purpose] This study aimed to compare dynamic balance with respect to completing a single task while not using smartrphone function and completing two task while using different smartphone functions, therby preventing falls or injuries resulting from completion of dual tasks. [Subjects and Methods] The subjects of this study were 36 healthy males and females. The experiment was conducted for five situations: a Star Excursion Balance Test (SEBT) was performed (1) during single-tasking without a smartphone and during dual-tasking with a smartphone, (2) when listening to music using a smartphone, (3) when sending message using a smartphone, (4) when surfing the web using a smartphone, and (5) when playing a game using a smartphone. The condition were the same for all five experimentes. Random selection was done to prevent learing. All experiments were conducted three times, and the averaged values were used for analysis. The SEBT was performed in three directions: anterior, posterolateral, and posterormedial. In consideration the differences in leg length of the subjects, their actual leg length were measured to be used as percentages. Their leg length was measured from the anterior superior iliac spine of the femur to the medial malleolus. [Results] Compared with single task not done using a smartphone, dynamic balance statistically significantly changed for dual tasks done using a smartphone in all three directions. Dynamic balance decreased in all three directions when playing games, sending messages, web surfing, and listening to music. [Conclusion] Completing two tasks using a smartphone reduced cognitive ability, decreasing dynamic balance. Therefore, performing a single task rather than using the diverse functions of a smartphone while walking or working is considered a factor that can prevent falls and injuries. PMID:25729208

  1. Test-retest reliability of stride time variability while dual tasking in healthy and demented adults with frontotemporal degeneration

    PubMed Central

    2011-01-01

    Background Although test-retest reliability of mean values of spatio-temporal gait parameters has been assessed for reliability while walking alone (i.e., single tasking), little is known about the test-retest reliability of stride time variability (STV) while performing an attention demanding-task (i.e., dual tasking). The objective of this study was to examine immediate test-retest reliability of STV while single and dual tasking in cognitively healthy older individuals (CHI) and in demented patients with frontotemporal degeneration (FTD). Methods Based on a cross-sectional design, 69 community-dwelling CHI (mean age 75.5 ± 4.3; 43.5% women) and 14 demented patients with FTD (mean age 65.7 ± 9.8 years; 6.7% women) walked alone (without performing an additional task; i.e., single tasking) and while counting backward (CB) aloud starting from 50 (i.e., dual tasking). Each subject completed two trials for all the testing conditions. The mean value and the coefficient of variation (CoV) of stride time while walking alone and while CB at self-selected walking speed were measured using GAITRite® and SMTEC® footswitch systems. Results ICC of mean value in CHI under both walking conditions were higher than ICC of demented patients with FTD and indicated perfect reliability (ICC > 0.80). Reliability of mean value was better while single tasking than dual tasking in CHI (ICC = 0.96 under single-task and ICC = 0.86 under dual-task), whereas it was the opposite in demented patients (ICC = 0.65 under single-task and ICC = 0.81 under dual-task). ICC of CoV was slight to poor whatever the group of participants and the walking condition (ICC < 0.20), except while dual tasking in demented patients where it was fair (ICC = 0.34). Conclusions The immediate test-retest reliability of the mean value of stride time in single and dual tasking was good in older CHI as well as in demented patients with FTD. In contrast, the variability of stride time was low in both groups of

  2. Dual task-related gait changes in patients with mild cognitive impairment

    PubMed Central

    Nascimbeni, Alberto; Caruso, Shiva; Salatino, Adriana; Carenza, Marinella; Rigano, Marta; Raviolo, Andrea; Ricci, Raffaella

    2015-01-01

    Summary Mild cognitive impairment (MCI) entails a high risk of developing Alzheimer’s dementia. In MCI patients gait impairment, which increases the risk of falls and institutionalization, is an early motor sign. A dual-task (DT) paradigm might improve the observation of this phenomenon. The aim of this study was to investigate motor-cognitive interference in a sample of MCI patients and a group of matched healthy controls submitted to DT conditions. To this end, three different cognitive tasks were used: counting backwards, short story recall and a phonemic fluency task. Overall, the patients, compared with the healthy participants, performed worse on the cognitive tasks and showed some degree of gait impairment. In the DT conditions, both groups showed significant gait disruption independently of the concomitant cognitive task. As regards cognitive performance, counting backwards worsened during dual tasking, while short story recall improved in both groups. Overall, our results suggest that the use of a DT paradigm does not improve the early detection of MCI. Our findings of enhanced story recall during walking might have interesting implications for rehabilitation of memory function. PMID:26214028

  3. Modulation of hyperactive error signals in obsessive-compulsive disorder by dual-task demands.

    PubMed

    Klawohn, Julia; Endrass, Tanja; Preuss, Julia; Riesel, Anja; Kathmann, Norbert

    2016-02-01

    Brain correlates of performance-monitoring have been shown to be hyperactive in patients with obsessive-compulsive disorder (OCD), indexed by enhanced amplitudes of the error-related negativity (ERN) in the event-related potential (ERP). This hyperactivity was found to be temporally stable, independent of symptom remission, and could not be further increased by punishing committed errors. The current study examined whether the ERN in OCD is generally insensitive to modulatory influences or can be decreased by manipulation of task demands. Twenty-two OCD patients and 22 control participants performed a flanker task alone or with a concurrent n-back task to manipulate attentional resource allocation. Response-related ERP data were examined. OCD patients showed enhanced ERN-amplitudes in the standard flanker (ηp2 = .13). In both groups a significant decrease in ERN was found under dual-task conditions (ηp2 = .72) that was larger in the OCD group (ηp2 = .14), resulting in a nonsignificant ERN group difference in dual-task conditions. The current study replicated enhanced performance-monitoring in OCD as indexed by higher ERN-amplitudes. Importantly, it further showed a larger ERN-reduction with dual-task demands in patients compared to healthy participants. These results suggest that overactive performance-monitoring was normalized in patients with OCD by experimental conditions. Changing the attentional focus appears to be an effective strategy in modifying hyperactive error-signals in OCD and might be a target for innovative interventions. PMID:26692121

  4. [Psychological and stabilographic features in healthy persons performing dual tasks with different quality].

    PubMed

    2013-01-01

    The results of performance of 40 healthy volunteers (29.8 ± 2.47 y.o.) in four dual tasks that included postural balance task as a motor sub-task and calculation as a cognitive sub-task were compared to results of individual psychological assessment which measured working and spatial memory capacity, speed of attention switch etc. Performance of participants in dual tasks was not uniform. For each of four tasks four types of performance were observed. Those included decrease of performance in both or one task and increase of performance in both tasks. In one of the four dual tasks 30% of the group of participants performed in both components of dual task better then in separate motor and cognitive tasks. Better performance in this dual task correlated with higher speed of attention switch, higher estimates of spatial and working memory. Analysis of results of psychological and stabilografic investigations showed negative correlation between speed of sway of center of pressure (CoP) and speed of attention switch test, and also between amplitude of CoP sway along frontal axis and capacity of spatial and working memory. These correlations reflect involvement of cognitive resources in voluntary postural control and motor automatism in successful dual task performance. Selected variant of dual task could be used as an instrument of selection of individuals for activities related to high informational loads. PMID:25508959

  5. [Psychological and stabilographic features in healthy persons performing dual tasks with different quality].

    PubMed

    Zharikov, A V; Zhavoronkova, L A; Kuptsova, S B; Kushnir, E M; Kulikov, M A; Mikhalkova, A A

    2013-01-01

    The results of performance of 40 healthy volunteers (29.8 ± 2.47 y.o.) in four dual tasks that included postural balance task as a motor sub-task and calculation as a cognitive sub-task were compared to results of individual psychological assessment which measured working and spatial memory capacity, speed of attention switch etc. Performance of participants in dual tasks was not uniform. For each of four tasks four types of performance were observed. Those included decrease of performance in both or one task and increase of performance in both tasks. In one of the four dual tasks 30% of the group of participants performed in both components of dual task better then in separate motor and cognitive tasks. Better performance in this dual task correlated with higher speed of attention switch, higher estimates of spatial and working memory. Analysis of results of psychological and stabilografic investigations showed negative correlation between speed of sway of center of pressure (CoP) and speed of attention switch test, and also between amplitude of CoP sway along frontal axis and capacity of spatial and working memory. These correlations reflect involvement of cognitive resources in voluntary postural control and motor automatism in successful dual task performance. Selected variant of dual task could be used as an instrument of selection of individuals for activities related to high informational loads. PMID:25486828

  6. Stopping while Going! Response Inhibition Does Not Suffer Dual-Task Interference

    ERIC Educational Resources Information Center

    Yamaguchi, Motonori; Logan, Gordon D.; Bissett, Patrick G.

    2012-01-01

    Although dual-task interference is ubiquitous in a variety of task domains, stop-signal studies suggest that response inhibition is not subject to such interference. Nevertheless, no study has directly examined stop-signal performance in a dual-task setting. In two experiments, stop-signal performance was examined in a psychological refractory…

  7. Transcranial Direct Current Stimulation to Enhance Dual-Task Gait Training in Parkinson’s Disease: A Pilot RCT

    PubMed Central

    Schabrun, Siobhan M.; Lamont, Robyn M.; Brauer, Sandra G.

    2016-01-01

    Objective To investigate the feasibility and safety of a combined anodal transcranial direct current stimulation (tDCS) and dual task gait training intervention in people with Parkinson’s Disease (PD) and to provide data to support a sample size calculation for a fully powered trial should trends of effectiveness be present. Design A pilot, randomized, double-blind, sham-controlled parallel group trial with 12 week follow-up. Setting A university physiotherapy department. Interventions Sixteen participants diagnosed with PD received nine dual task gait training sessions over 3 weeks. Participants were randomized to receive either active or sham tDCS applied for the first 20 minutes of each session. Main Measures The primary outcome was gait speed while undertaking concurrent cognitive tasks (word lists, counting, conversation). Secondary measures included step length, cadence, Timed Up and Go, bradykinesia and motor speed. Results Gait speed, step length and cadence improved in both groups, under all dual task conditions. This effect was maintained at follow-up. There was no difference between the active and sham tDCS groups. Time taken to perform the TUGwords also improved, with no difference between groups. The active tDCS group did however increase their correct cognitive response rate during the TUGwords and TUGcount. Bradykinesia improved after training in both groups. Conclusion Three weeks of dual task gait training resulted in improved gait under dual task conditions, and bradykinesia, immediately following training and at 12 weeks follow-up. The only parameter enhanced by tDCS was the number of correct responses while performing the dual task TUG. tDCS applied to M1 may not be an effective adjunct to dual task gait training in PD. Trial Registration Australia-New Zealand Clinical Trials Registry ACTRN12613001093774 PMID:27359338

  8. Interference effects of vocalization on dual task performance

    NASA Astrophysics Data System (ADS)

    Owens, J. M.; Goodman, L. S.; Pianka, M. J.

    1984-09-01

    Voice command and control systems have been proposed as a potential means of off-loading the typically overburdened visual information processing system. However, prior to introducing novel human-machine interfacing technologies in high workload environments, consideration must be given to the integration of the new technologists within existing task structures to ensure that no new sources of workload or interference are systematically introduced. This study examined the use of voice interactive systems technology in the joint performance of two cognitive information processing tasks requiring continuous memory and choice reaction wherein a basis for intertask interference might be expected. Stimuli for the continuous memory task were presented aurally and either voice or keyboard responding was required in the choice reaction task. Performance was significantly degraded in each task when voice responding was required in the choice reaction time task. Performance degradation was evident in higher error scores for both the choice reaction and continuous memory tasks. Performance decrements observed under conditions of high intertask stimulus similarity were not statistically significant. The results signal the need to consider further the task requirements for verbal short-term memory when applying speech technology in multitask environments.

  9. Influence of dual-task on postexercise facilitation: a transcranial magnetic stimulation study.

    PubMed

    Concerto, Carmen; Amer, Bahaa; Abagyan, Anaida; Cao, Yisheng; Infortuna, Carmenrita; Chusid, Eileen; Coira, Diego; Battaglia, Fortunato

    2016-06-01

    In this study we investigated the effect of a dual task (DT) comprised of a nonfatiguing leg and foot extension coupled with a calculation task on postexercise facilitation (PEF) of motor evoked potentials (MEPs) tested by using transcranial magnetic stimulation (TMS). Twelve right-handed healthy subjects participated in the study. They were required to perform a motor task, a cognitive task and a DT. The motor task consisted of extending the right leg and foot for 30 sec at 20% of the maximal voluntary contraction. The cognitive task consisted of a 30-sec backward calculation. In the DT condition, motor and cognitive tasks were performed concurrently. Resting motor threshold and 10 MEPs were collected before and immediately after each task. TMS was delivered to the motor hot spot of the right vastus lateralis and tibialis anterior (TA) muscles. Results showed that exercise induced a significant PEF in both VL and TA muscles while calculation was not associated with significant PEF. Furthermore, DT was associated with lack of significant PEF in both muscles (VL, 116.1%±9.6%; TA, 115.7%±9%). Our data indicates DT interference on corticospinal excitability after a nonfatiguing exercise. Our experimental paradigm may be used to address postexercise motor cortex plastic adaptations induced by motor and cognitive tasks of different complexity in sport, aging and neuropsychiatric diseases. PMID:27419111

  10. Influence of dual-task on postexercise facilitation: a transcranial magnetic stimulation study.

    PubMed

    Concerto, Carmen; Amer, Bahaa; Abagyan, Anaida; Cao, Yisheng; Infortuna, Carmenrita; Chusid, Eileen; Coira, Diego; Battaglia, Fortunato

    2016-06-01

    In this study we investigated the effect of a dual task (DT) comprised of a nonfatiguing leg and foot extension coupled with a calculation task on postexercise facilitation (PEF) of motor evoked potentials (MEPs) tested by using transcranial magnetic stimulation (TMS). Twelve right-handed healthy subjects participated in the study. They were required to perform a motor task, a cognitive task and a DT. The motor task consisted of extending the right leg and foot for 30 sec at 20% of the maximal voluntary contraction. The cognitive task consisted of a 30-sec backward calculation. In the DT condition, motor and cognitive tasks were performed concurrently. Resting motor threshold and 10 MEPs were collected before and immediately after each task. TMS was delivered to the motor hot spot of the right vastus lateralis and tibialis anterior (TA) muscles. Results showed that exercise induced a significant PEF in both VL and TA muscles while calculation was not associated with significant PEF. Furthermore, DT was associated with lack of significant PEF in both muscles (VL, 116.1%±9.6%; TA, 115.7%±9%). Our data indicates DT interference on corticospinal excitability after a nonfatiguing exercise. Our experimental paradigm may be used to address postexercise motor cortex plastic adaptations induced by motor and cognitive tasks of different complexity in sport, aging and neuropsychiatric diseases.

  11. Influence of dual-task on postexercise facilitation: a transcranial magnetic stimulation study

    PubMed Central

    Concerto, Carmen; Amer, Bahaa; Abagyan, Anaida; Cao, Yisheng; Infortuna, Carmenrita; Chusid, Eileen; Coira, Diego; Battaglia, Fortunato

    2016-01-01

    In this study we investigated the effect of a dual task (DT) comprised of a nonfatiguing leg and foot extension coupled with a calculation task on postexercise facilitation (PEF) of motor evoked potentials (MEPs) tested by using transcranial magnetic stimulation (TMS). Twelve right-handed healthy subjects participated in the study. They were required to perform a motor task, a cognitive task and a DT. The motor task consisted of extending the right leg and foot for 30 sec at 20% of the maximal voluntary contraction. The cognitive task consisted of a 30-sec backward calculation. In the DT condition, motor and cognitive tasks were performed concurrently. Resting motor threshold and 10 MEPs were collected before and immediately after each task. TMS was delivered to the motor hot spot of the right vastus lateralis and tibialis anterior (TA) muscles. Results showed that exercise induced a significant PEF in both VL and TA muscles while calculation was not associated with significant PEF. Furthermore, DT was associated with lack of significant PEF in both muscles (VL, 116.1%±9.6%; TA, 115.7%±9%). Our data indicates DT interference on corticospinal excitability after a nonfatiguing exercise. Our experimental paradigm may be used to address postexercise motor cortex plastic adaptations induced by motor and cognitive tasks of different complexity in sport, aging and neuropsychiatric diseases. PMID:27419111

  12. The Role of Outcome Conflict in Dual-Task Interference. ICS Report 8601.

    ERIC Educational Resources Information Center

    Navon, David; Miller, Jeff

    The traditional explanation for dual-task interference is that tasks compete for scarce processing resources. Another possible explanation is that the outcome of the processing required for one task conflicts with the processing required for the other task. To explore the contribution of outcome conflict to task interference, this paper describes…

  13. Effects of Aging on Arm Swing during Gait: The Role of Gait Speed and Dual Tasking

    PubMed Central

    Mirelman, Anat; Bernad-Elazari, Hagar; Nobel, Tomer; Thaler, Avner; Peruzzi, Agnese; Plotnik, Meir; Giladi, Nir; Hausdorff, Jeffrey M.

    2015-01-01

    Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty healthy adults between the ages of 30–77 were included in this study designed to address this gap. Lightweight body fixed sensors were placed on each wrist and lower back. Participants walked under 3 walking conditions each of 1 minute: 1) comfortable speed, 2) walking while serially subtracting 3’s (Dual Task), 3) walking at fast speed. Aging effects on arm swing amplitude, range, symmetry, jerk and axial rotation amplitude and jerk were compared between decades of age (30–40; 41–50; 51–60; 61–77 years). As expected, older adults walked slower (p = 0.03) and with increased stride variability (p = 0.02). Arm swing amplitude decreased with age under all conditions (p = 0.04). In the oldest group, arm swing decreased during dual task and increased during the fast walking condition (p<0.0001). Similarly, arm swing asymmetry increased during the dual task in the older groups (p<0.004), but not in the younger groups (p = 0.67). Significant differences between groups and within conditions were observed in arm swing jerk (p<0.02), axial rotation amplitude (p<0.02) and axial jerk (p<0.001). Gait speed, arm swing amplitude of the dominant arm, arm swing asymmetry and axial rotation jerk were all independent predictors of age in a multivariate model. These findings suggest that the effects of gait speed and dual tasking on arm swing and axial rotation during walking are altered among healthy older adults. Follow-up work is needed to examine if these effects contribute to reduced stability in aging. PMID:26305896

  14. Effect of short and long exposure duration and dual-tasking on a global-local task.

    PubMed

    Andres, Allison J D; Fernandes, Myra A

    2006-07-01

    Past research has demonstrated a global advantage in responses to visually presented hierarchical stimuli such that, on incongruent trials, the global form interferes with responses to the local level [Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112, 24-38]. In Experiment 1, 32 adults performed alternating blocks of global or local identification of hierarchical letter stimuli in which the global and local letters were congruent, incongruent, or neutral, and were presented at either a short (17 ms) or long (100 ms) exposure duration. A global advantage was demonstrated at both durations. In the local-directed task, interference on incongruent, relative to neutral, trials was observed at both exposure durations, but facilitation on congruent trials, relative to neutral trials, was present only when stimuli were presented at the long exposure duration. In Experiment 2, global or local identification was performed by another group of 24 adults at either a long or short exposure duration, and also under conditions of full attention (FA) or dual-task (DT) conditions with a digit-monitoring task. Under FA, we again found significant interference at both exposure durations, but facilitation only at the long exposure duration. Under DT conditions, the pattern of facilitation and interference at the short duration remained unchanged. At the long duration, however, dual-tasking eliminated interference in the RT but not error data, while facilitation was present in both sets of data. Results are in line with a perceptual account of the global advantage, and suggest that facilitation requires consciously-mediated processes, whereas interference does not.

  15. Age Differences between Children and Young Adults in the Dynamics of Dual-Task Prioritization: Body (Balance) versus Mind (Memory)

    ERIC Educational Resources Information Center

    Schaefer, Sabine; Krampe, Ralf Th.; Lindenberger, Ulman; Baltes, Paul B.

    2008-01-01

    Task prioritization can lead to trade-off patterns in dual-task situations. The authors compared dual-task performances in 9- and 11-year-old children and young adults performing a cognitive task and a motor task concurrently. The motor task required balancing on an ankle-disc board. Two cognitive tasks measured working memory and episodic memory…

  16. Evaluation of an inertial sensor system for analysis of timed-up-and-go under dual-task demands.

    PubMed

    Coulthard, Jason T; Treen, Tanner T; Oates, Alison R; Lanovaz, Joel L

    2015-05-01

    Functional tests, such as the timed-up-and-go (TUG), are routinely used to screen for mobility issues and fall risk. While the TUG is easy to administer and evaluate, its single time-to-completion outcome may not discriminate between different mobility challenges. Wearable sensors provide an opportunity to collect a variety of additional variables during clinical tests. The purpose of this study was to assess a new wearable inertial sensor system (iTUG) by investigating the effects of cognitive tasks in a dual-task paradigm on spatiotemporal and kinematic variables during the TUG. No previous studies have looked at both spatiotemporal variables and kinematics during dual-task TUG tests. 20 healthy young participants (10 males) performed a total 15 TUG trials with two different cognitive tasks and a normal control condition. Total time, along with spatiotemporal gait parameters and kinematics for all TUG subtasks (sit-to-stand, walking, turn, turn-to-sit), were measured using the inertial sensors. Time-to-completion from iTUG was highly correlated with concurrent manual timing. Spatiotemporal variables during walking showed expected differences between control and cognitive dual-tasks while trunk kinematics appeared to show more sensitivity to dual-tasks than reported previously in straight line walking. Non-walking TUG subtasks showed only minor changes during dual-task conditions indicating a possible attentional shift away from the cognitive task. Stride length and some variability measures were significantly different between the two cognitive tasks suggesting an ability to discriminate between tasks. Overall, the use of the iTUG system allows the collection of both traditional and potentially more discriminatory variables with a protocol that is easily used in a clinical setting.

  17. Individual differences in oscillatory brain activity in response to varying attentional demands during a word recall and oculomotor dual task

    PubMed Central

    Kwon, Gusang; Lim, Sanghyun; Kim, Min-Young; Kwon, Hyukchan; Lee, Yong-Ho; Kim, Kiwoong; Lee, Eun-Ju; Suh, Minah

    2015-01-01

    Every day, we face situations that involve multi-tasking. How our brain utilizes cortical resources during multi-tasking is one of many interesting research topics. In this study, we tested whether a dual-task can be differentiated in the neural and behavioral responses of healthy subjects with varying degree of working memory capacity (WMC). We combined word recall and oculomotor tasks because they incorporate common neural networks including the fronto-parietal (FP) network. Three different types of oculomotor tasks (eye fixation, Fix-EM; predictive and random smooth pursuit eye movement, P-SPEM and R-SPEM) were combined with two memory load levels (low-load: five words, high-load: 10 words) for a word recall task. Each of those dual-task combinations was supposed to create varying cognitive loads on the FP network. We hypothesize that each dual-task requires different cognitive strategies for allocating the brain’s limited cortical resources and affects brain oscillation of the FP network. In addition, we hypothesized that groups with different WMC will show differential neural and behavioral responses. We measured oscillatory brain activity with simultaneous MEG and EEG recordings and behavioral performance by word recall. Prominent frontal midline (FM) theta (4–6 Hz) synchronization emerged in the EEG of the high-WMC group experiencing R-SPEM with high-load conditions during the early phase of the word maintenance period. Conversely, significant parietal upper alpha (10–12 Hz) desynchronization was observed in the EEG and MEG of the low-WMC group experiencing P-SPEM under high-load conditions during the same period. Different brain oscillatory patterns seem to depend on each individual’s WMC and varying attentional demands from different dual-task combinations. These findings suggest that specific brain oscillations may reflect different strategies for allocating cortical resources during combined word recall and oculomotor dual-tasks. PMID:26175681

  18. Neurofeedback training improves the dual-task performance ability in stroke patients.

    PubMed

    Lee, Young-Shin; Bae, Sea-Hyun; Lee, Sung-Hee; Kim, Kyung-Yoon

    2015-01-01

    Owing to the reduced capacity for information processing following a stroke, patients commonly present with difficulties in performing activities of daily living that combine two or more tasks. To address this problem, in the present study, we investigated the effects of neurofeedback training on the abilities of stroke patients to perform dual motor tasks. We randomly assigned 20 patients who had sustained a stroke within the preceding 6 months to either a pseudo-neurofeedback (n = 10) or neurofeedback (n = 10) group. Both groups participated in a general exercise intervention for 8 weeks, three times a week for 30 min per session, under the same conditions. An electrode was secured to the scalp over the region of the central lobe (Cz), in compliance with the International 10-20 System. The electrode was inactive for the pseudo-training group. Participants in the neurofeedback training group received the 30-min neurofeedback training per session for reinforcing the sensorimotor rhythm. Electroencephalographic activity of the two groups was compared. In addition, selected parameters of gait (velocity, cadence [step/min], stance phase [%], and foot pressure) were analyzed using a 10-m walk test, attention-demanding task, walk task and quantified by the SmartStep system. The neurofeedback group showed significantly improved the regulation of the sensorimotor rhythm (p < 0.001) and ability to execute dual tasks (p < 0.01). Significant improvements on selected gait parameters (velocity and cadence; p < 0.05) were also observed. We thus propose that the neurofeedback training is effective to improve the dual-task performance in stroke patients.

  19. Do frailty and cognitive impairment affect dual-task cost during walking in the oldest old institutionalized patients?

    PubMed

    Cadore, Eduardo L; Casas-Herrero, Alvaro; Zambom-Ferraresi, Fabricio; Martínez-Ramírez, Alicia; Millor, Nora; Gómez, Marisol; Moneo, Ana B Bays; Izquierdo, Mikel

    2015-12-01

    The objective of this study was to investigate dual-task costs in several elderly populations, including robust oldest old, frail oldest old with MCI, frail oldest old without MCI, and frail elderly with dementia. Sixty-four elderly men and women categorized into frail without MCI (age 93.4 ± 3.2 years, n = 20), frail with MCI (age 92.4 ± 4.2 years, n = 13), robust (age 88.2 ± 4.1 years, n = 10), and patients with dementia (age 88.1 ± 5.1 years, n = 21). Five-meter gait ability and timed-up-and-go (TUG) tests with single and dual-task performance were assessed in the groups. Dual-task cost in both 5-m habitual gait velocity test and TUG test was calculated by the time differences between single and dual-task performance. The robust group exhibited better 5-m gait and TUG test performances in the single and dual-task conditions compared with the other three groups (P < 0.001), and the frail and frail + MCI groups exhibited better performances than the dementia group (P < 0.001). No significant differences were observed between the frail and frail + MCI groups. However, all groups exhibited lower gait velocities in the verbal and arithmetic task conditions, but the dual-task cost of the groups were similar. Robust individuals exhibited superior single and dual-task walking performances than the other three groups, and the frail and frail + MCI individuals exhibited performances that were superior to those of the patients with dementia. However, the dual-task costs, i.e., the changes in gait performance when elderly participants switch from a single to a dual task, were similar among all four of the investigated groups. Therefore, these results demonstrated that the magnitude of the impairment in gait pattern is independent of frailty and cognitive impairment status.

  20. Do frailty and cognitive impairment affect dual-task cost during walking in the oldest old institutionalized patients?

    PubMed

    Cadore, Eduardo L; Casas-Herrero, Alvaro; Zambom-Ferraresi, Fabricio; Martínez-Ramírez, Alicia; Millor, Nora; Gómez, Marisol; Moneo, Ana B Bays; Izquierdo, Mikel

    2015-12-01

    The objective of this study was to investigate dual-task costs in several elderly populations, including robust oldest old, frail oldest old with MCI, frail oldest old without MCI, and frail elderly with dementia. Sixty-four elderly men and women categorized into frail without MCI (age 93.4 ± 3.2 years, n = 20), frail with MCI (age 92.4 ± 4.2 years, n = 13), robust (age 88.2 ± 4.1 years, n = 10), and patients with dementia (age 88.1 ± 5.1 years, n = 21). Five-meter gait ability and timed-up-and-go (TUG) tests with single and dual-task performance were assessed in the groups. Dual-task cost in both 5-m habitual gait velocity test and TUG test was calculated by the time differences between single and dual-task performance. The robust group exhibited better 5-m gait and TUG test performances in the single and dual-task conditions compared with the other three groups (P < 0.001), and the frail and frail + MCI groups exhibited better performances than the dementia group (P < 0.001). No significant differences were observed between the frail and frail + MCI groups. However, all groups exhibited lower gait velocities in the verbal and arithmetic task conditions, but the dual-task cost of the groups were similar. Robust individuals exhibited superior single and dual-task walking performances than the other three groups, and the frail and frail + MCI individuals exhibited performances that were superior to those of the patients with dementia. However, the dual-task costs, i.e., the changes in gait performance when elderly participants switch from a single to a dual task, were similar among all four of the investigated groups. Therefore, these results demonstrated that the magnitude of the impairment in gait pattern is independent of frailty and cognitive impairment status. PMID:26667940

  1. Effect of dual-task training on postural stability in children with infantile hemiparesis

    PubMed Central

    Elhinidi, Elbadawi Ibrahim Mohammad; Ismaeel, Marwa Mostafa Ibrahim; El-Saeed, Tamer Mohamed

    2016-01-01

    [Purpose] The aim of this study was to evaluate the influence of using a selected dual-task training program to improve postural stability in infantile hemiparesis. [Subjects and Methods] Thirty patients participated in this study; patients were classified randomly into two equal groups: study and control groups. Both groups received conventional physical therapy treatment including mobility exercises, balance exercises, gait training exercises, and exercises to improve physical conditioning. In addition, the study group received a selected dual-task training program including balance and cognitive activities. The treatment program was conducted thrice per week for six successive weeks. The patients were assessed with the Biodex Balance System. These measures were recorded two times: before the application of the treatment program (pre) and after the end of the treatment program (post). [Results] There was a significant improvement for both groups; the improvement was significantly higher in the study group compared to the control group. [Conclusion] The selected dual-task training program is effective in improving postural stability in patients with infantile hemiparesis when added to the conventional physical therapy program. PMID:27134376

  2. Eliminating dual-task costs by minimizing crosstalk between tasks: The role of modality and feature pairings.

    PubMed

    Göthe, Katrin; Oberauer, Klaus; Kliegl, Reinhold

    2016-05-01

    We tested the independent influences of two content-based factors on dual-task costs, and on the parallel processing ability: The pairing of S-R modalities and the pairing of relevant features between stimuli and responses of two tasks. The two pairing factors were realized across four dual-task groups. Within each group the two tasks comprised two different stimulus modalities (visual and auditory), two different relevant stimulus features (spatial and verbal) and two response modalities (manual and vocal). Pairings of S-R modalities (standard: visual-manual and auditory-vocal, non-standard: visual-vocal and auditory-manual) and feature pairings (standard: spatial-manual and verbal-vocal, non-standard: spatial-vocal and verbal-manual) varied across groups. All participants practiced their respective dual-task combination in a paradigm with simultaneous stimulus onset before being transferred to a psychological refractory period paradigm varying stimulus-onset asynchrony. A comparison at the end of practice revealed similar dual-task costs and similar pairing effects in both paradigms. Dual-task costs depended on modality and feature pairings. Groups training with non-standard feature pairings (i.e., verbal stimulus features mapped to spatially separated response keys, or spatial stimulus features mapped to verbal responses) and non-standard modality pairings (i.e., auditory stimulus mapped to manual response, or visual stimulus mapped to vocal responses) had higher dual-task costs than respective standard pairings. In contrast, irrespective of modality pairing dual-task costs virtually disappeared with standard feature pairings after practice in both paradigms. The results can be explained by crosstalk between feature-binding processes for the two tasks. Crosstalk was present for non-standard but absent for standard feature pairings. Therefore, standard feature pairings enabled parallel processing at the end of practice.

  3. Attentional Modulation of Word Recognition by Children in a Dual-Task Paradigm

    ERIC Educational Resources Information Center

    Choi, Sangsook; Lotto, Andrew; Lewis, Dawna; Hoover, Brenda; Stelmachowicz, Patricia

    2008-01-01

    Purpose: This study investigated an account of limited short-term memory capacity for children's speech perception in noise using a dual-task paradigm. Method: Sixty-four normal-hearing children (7-14 years of age) participated in this study. Dual tasks were repeating monosyllabic words presented in noise at 8 dB signal-to-noise ratio and…

  4. Capacity Demands of Phoneme Selection in Word Production: New Evidence from Dual-Task Experiments

    ERIC Educational Resources Information Center

    Cook, Amy E.; Meyer, Antje S.

    2008-01-01

    Three dual-task experiments investigated the capacity demands of phoneme selection in picture naming. On each trial, participants named a target picture (Task 1) and carried out a tone discrimination task (Task 2). To vary the time required for phoneme selection, the authors combined the targets with phonologically related or unrelated distractor…

  5. Walking in School-Aged Children in a Dual-Task Paradigm Is Related to Age But Not to Cognition, Motor Behavior, Injuries, or Psychosocial Functioning

    PubMed Central

    Hagmann-von Arx, Priska; Manicolo, Olivia; Lemola, Sakari; Grob, Alexander

    2016-01-01

    Age-dependent gait characteristics and associations with cognition, motor behavior, injuries, and psychosocial functioning were investigated in 138 typically developing children aged 6.7–13.2 years (M = 10.0 years). Gait velocity, normalized velocity, and variability were measured using the walkway system GAITRite without an additional task (single task) and while performing a motor or cognitive task (dual task). Assessment of children’s cognition included tests for intelligence and executive functions; parents reported on their child’s motor behavior, injuries, and psychosocial functioning. Gait variability (an index of gait regularity) decreased with increasing age in both single- and dual-task walking. Dual-task gait decrements were stronger when children walked in the motor compared to the cognitive dual-task condition and decreased with increasing age in both dual-task conditions. Gait alterations from single- to dual-task conditions were not related to children’s cognition, motor behavior, injuries, or psychosocial functioning. PMID:27014158

  6. Effects of Physical Exercise Interventions on Gait-Related Dual-Task Interference in Older Adults: A Systematic Review and Meta-Analysis.

    PubMed

    Plummer, Prudence; Zukowski, Lisa A; Giuliani, Carol; Hall, Amber M; Zurakowski, David

    2015-01-01

    Dual-task interference during walking can substantially limit mobility and increase the risk of falls among community-dwelling older adults. Previous systematic reviews examining intervention effects on dual-task gait and mobility have not assessed relative dual-task costs (DTC) or investigated whether there are differences in treatment-related changes based on the type of dual task or the type of control group. The purpose of this systematic review was to examine the effects of physical exercise interventions on dual-task performance during walking in older adults. A meta-analysis of randomized controlled trials (RCTs) compared treatment effects between physical exercise intervention and control groups on single- and dual-task gait speed and relative DTC on gait speed. A systematic search of the literature was conducted using the electronic databases PubMed, CINAHL, EMBASE, Web of Science, and PsycINFO searched up to September 19, 2014. Randomized, nonrandomized, and uncontrolled studies published in English and involving older adults were selected. Studies had to include a physical exercise intervention protocol and measure gait parameters during continuous, unobstructed walking in single- and dual-task conditions before and after the intervention. Of 614 abstracts, 21 studies met the inclusion criteria and were included in the systematic review. Fourteen RCTs were included in the meta-analysis. The mean difference between the intervention and control groups significantly favored the intervention for single-task gait speed (mean difference: 0.06 m/s, 95% CI: 0.03, 0.10, p < 0.001), dual-task gait speed (mean difference: 0.11 m/s, 95% CI 0.07, 0.15, p < 0.001), and DTC on gait speed (mean difference: 5.23%, 95% CI 1.40, 9.05, p = 0.007). Evidence from subgroup comparisons showed no difference in treatment-related changes between cognitive-motor and motor-motor dual tasks, or when interventions were compared to active or inactive controls. In summary, physical

  7. Decision criteria in dual discrimination tasks estimated using external-noise methods.

    PubMed

    Zak, Ido; Katkov, Mikhail; Gorea, Andrei; Sagi, Dov

    2012-07-01

    According to classical signal detection theory (SDT), in simple detection or discrimination tasks, observers use a decision parameter based on their noisy internal response to set a boundary between "yes" and "no" responses. Experimental paradigms where performance is limited by internal noise cannot be used to provide an unambiguous measure of the decision criterion and its variability. Here, unidimensional external noise is used to estimate a criterion and its variability in stimulus space. Within this paradigm, the criterion is defined as the stimulus value separating the two response alternatives. This paradigm allows the assessment of interactions between criteria assigned to different targets in dual tasks. Previous studies suggested that observers' criteria interacted or even collapsed to one (hence, nonoptimal) criterion. An alternative interpretation of those results is that observers equated their false alarm (FA) rates. The external-noise method enables the confrontation of the two hypotheses. It is shown that the variability of observers' criterion in stimulus space is about 1.6 times their measured sensory threshold, suggesting that the presence of external noise increases decision uncertainty. Observers' stimulus criterion settings are close to SDT predictions in single tasks, but not in dual tasks where the two criteria tend to "attract" each other. Observers maintain distinct FA rates even when SDT predicts equal rates. Observers trained in psychophysics or provided with basic notions of SDT exemplified with the present experimental design manage to better separate their criteria in some conditions. PMID:22351481

  8. Musical Training, Bilingualism, and Executive Function: A Closer Look at Task Switching and Dual-Task Performance

    ERIC Educational Resources Information Center

    Moradzadeh, Linda; Blumenthal, Galit; Wiseheart, Melody

    2015-01-01

    This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual-task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non-musician, or monolingual non-musician)…

  9. The Effect of Two Different Cognitive Tests on Gait Parameters during Dual Tasks in Healthy Postmenopausal Women

    PubMed Central

    Kałużny, Krystian; Hagner, Wojciech; Kałużna, Anna; Kochański, Bartosz; Borkowska, Alina; Budzyński, Jacek

    2016-01-01

    Introduction. The paper aims to evaluate the influence of two different demanding cognitive tasks on gait parameters using BTS SMART system analysis. Patients and Methods. The study comprised 53 postmenopausal women aged 64.5 ± 6.7 years (range: 47–79). For every subject, gait analysis using a BTS SMART system was performed in a dual-task study design under three conditions: (I) while walking only (single task), (II) walking while performing a simultaneous simple cognitive task (SCT) (dual task), and (III) walking while performing a simultaneous complex cognitive task (CCT) (dual task). Time-space parameters of gait pertaining to the length of a single support phase, double support phase, gait speed, step length, step width, and leg swing speed were analyzed. Results. Performance of cognitive tests during gait resulted in a statistically significant prolongation of the left (by 7%) and right (by 7%) foot gait cycle, shortening of the length of steps made with the right extremity (by 4%), reduction of speed of swings made with the left (by 11%) and right (by 8%) extremity, and reduction in gait speed (by 6%). Conclusions. Performance of cognitive tests during gait changes its individual pattern in relation to the level of the difficulty of the task. PMID:27022602

  10. Dual task-related gait changes in patients with mild cognitive impairment.

    PubMed

    Nascimbeni, Alberto; Caruso, Shiva; Salatino, Adriana; Carenza, Marinella; Rigano, Marta; Raviolo, Andrea; Ricci, Raffaella

    2015-01-01

    Mild cognitive impairment (MCI) entails a high risk of developing Alzheimer's dementia. In MCI patients gait impairment, which increases the risk of falls and institutionalization, is an early motor sign. A dualtask (DT) paradigm might improve the observation of this phenomenon. The aim of this study was to investigate motor-cognitive interference in a sample of MCI patients and a group of matched healthy controls submitted to DT conditions. To this end, three different cognitive tasks were used: counting backwards, short story recall and a phonemic fluency task. Overall, the patients, compared with the healthy participants, performed worse on the cognitive tasks and showed some degree of gait impairment. In the DT conditions, both groups showed significant gait disruption independently of the concomitant cognitive task. As regards cognitive performance, counting backwards worsened during dual tasking, while short story recall improved in both groups. Overall, our results suggest that the use of a DT paradigm does not improve the early detection of MCI. Our findings of enhanced story recall during walking might have interesting implications for rehabilitation of memory function. PMID:26214028

  11. Recalibration of Inhibitory Control Systems during Walking-Related Dual-Task Interference: A Mobile Brain-Body Imaging (MOBI) Study

    PubMed Central

    De Sanctis, Pierfilippo; Butler, John S.; Malcolm, Brenda; Foxe, John J.

    2014-01-01

    Walking while simultaneously performing cognitively demanding tasks such as talking or texting are typical complex behaviors in our daily routines. Little is known about neural mechanisms underlying cortical resource allocation during such mobile actions, largely due to portability limitations of conventional neuroimaging technologies. We applied an EEG-based Mobile Brain-Body Imaging (MOBI) system that integrates high-density event-related potential (ERP) recordings with simultaneously acquired foot-force sensor data to monitor gait patterns and brain activity. We compared behavioral and ERP measures associated with performing a Go/NoGo response-inhibition task under conditions where participants (N=18) sat stationary, walked deliberately or walked briskly. This allowed for assessment of effects of increasing dual-task load (i.e. walking speed) on neural indices of inhibitory control. Stride time and variability were also measured during inhibitory task performance and compared to stride parameters without task performance, thereby assessing reciprocal dual-task effects on gait parameters. There were no task performance differences between sitting and either walking condition, indicating that participants could perform both tasks simultaneously without suffering dual-task costs. However, participants took longer strides under dual-task load, likely indicating an adaptive mechanism to reduce inter-task competition for cortical resources. We found robust differences in amplitude, latency and topography of ERP components (N2 and P3) associated with inhibitory control between the sitting and walking conditions. Considering that participants showed no dual-task performance costs, we suggest that observed neural alterations under increasing task-load represent adaptive recalibration of the inhibitory network towards a more controlled and effortful processing mode, thereby optimizing performance under dual-task situations. PMID:24642283

  12. Recalibration of inhibitory control systems during walking-related dual-task interference: a mobile brain-body imaging (MOBI) study.

    PubMed

    De Sanctis, Pierfilippo; Butler, John S; Malcolm, Brenda R; Foxe, John J

    2014-07-01

    Walking while simultaneously performing cognitively demanding tasks such as talking or texting are typical complex behaviors in our daily routines. Little is known about neural mechanisms underlying cortical resource allocation during such mobile actions, largely due to portability limitations of conventional neuroimaging technologies. We applied an EEG-based Mobile Brain-Body Imaging (MOBI) system that integrates high-density event-related potential (ERP) recordings with simultaneously acquired foot-force sensor data to monitor gait patterns and brain activity. We compared behavioral and ERP measures associated with performing a Go/NoGo response-inhibition task under conditions where participants (N=18) sat in a stationary way, walked deliberately or walked briskly. This allowed for assessment of effects of increasing dual-task load (i.e. walking speed) on neural indices of inhibitory control. Stride time and variability were also measured during inhibitory task performance and compared to stride parameters without task performance, thereby assessing reciprocal dual-task effects on gait parameters. There were no task performance differences between sitting and either walking condition, indicating that participants could perform both tasks simultaneously without suffering dual-task costs. However, participants took longer strides under dual-task load, likely indicating an adaptive mechanism to reduce inter-task competition for cortical resources. We found robust differences in amplitude, latency and topography of ERP components (N2 and P3) associated with inhibitory control between the sitting and walking conditions. Considering that participants showed no dual-task performance costs, we suggest that observed neural alterations under increasing task-load represent adaptive recalibration of the inhibitory network towards a more controlled and effortful processing mode, thereby optimizing performance under dual-task situations.

  13. Apolipoprotein E Genotype Linked to Spatial Gait Characteristics: Predictors of Cognitive Dual Task Gait Change

    PubMed Central

    MacAulay, Rebecca K.; Allaire, Ted; Brouillette, Robert; Foil, Heather; Bruce-Keller, Annadora J.; Keller, Jeffrey N.

    2016-01-01

    Background Developing measures to detect preclinical Alzheimer’s Disease is vital, as prodromal stage interventions may prove more efficacious in altering the disease’s trajectory. Gait changes may serve as a useful clinical heuristic that precedes cognitive decline. This study provides the first systematic investigation of gait characteristics relationship with relevant demographic, physical, genetic (Apolipoprotein E genotype), and health risk factors in non-demented older adults during a cognitive-load dual task walking condition. Methods The GAITRite system provided objective measurement of gait characteristics in APOE-e4 “carriers” (n = 75) and “non-carriers” (n = 224). Analyses examined stride length and step time gait characteristics during simple and dual-task (spelling five-letter words backwards) conditions in relation to demographic, physical, genetic, and health risk factors. Results Slower step time and shorter stride length associated with older age, greater health risk, and worse physical performance (ps < .05). Men and women differed in height, gait characteristics, health risk factors and global cognition (ps < .05). APOE-e4 associated with a higher likelihood of hypercholesterolemia and overall illness index scores (ps < .05). No genotype-sex interactions on gait were found. APOE-e4 was linked to shorter stride length and greater dual-task related disturbances in stride length. Conclusions Stride length has been linked to heightened fall risk, attention decrements and structural brain changes in older adults. Our results indicate that stride length is a useful behavioral marker of cognitive change that is associated with genetic risk for AD. Sex disparities in motor decline may be a function of health risk factors. PMID:27486898

  14. The influence of spatial congruency and movement preparation time on saccade curvature in simultaneous and sequential dual-tasks.

    PubMed

    Moehler, Tobias; Fiehler, Katja

    2015-11-01

    Saccade curvature represents a sensitive measure of oculomotor inhibition with saccades curving away from covertly attended locations. Here we investigated whether and how saccade curvature depends on movement preparation time when a perceptual task is performed during or before saccade preparation. Participants performed a dual-task including a visual discrimination task at a cued location and a saccade task to the same location (congruent) or to a different location (incongruent). Additionally, we varied saccade preparation time (time between saccade cue and Go-signal) and the occurrence of the discrimination task (during saccade preparation=simultaneous vs. before saccade preparation=sequential). We found deteriorated perceptual performance in incongruent trials during simultaneous task performance while perceptual performance was unaffected during sequential task performance. Saccade accuracy and precision were deteriorated in incongruent trials during simultaneous and, to a lesser extent, also during sequential task performance. Saccades consistently curved away from covertly attended non-saccade locations. Saccade curvature was unaffected by movement preparation time during simultaneous task performance but decreased and finally vanished with increasing movement preparation time during sequential task performance. Our results indicate that the competing saccade plan to the covertly attended non-saccade location is maintained during simultaneous task performance until the perceptual task is solved while in the sequential condition, in which the discrimination task is solved prior to the saccade task, oculomotor inhibition decays gradually with movement preparation time. PMID:26410291

  15. Raven's matrices and working memory: a dual-task approach.

    PubMed

    Rao, K Venkata; Baddeley, Alan

    2013-01-01

    Raven's Matrices Test was developed as a "pure" measure of Spearman's concept of general intelligence, g. Subsequent research has attempted to specify the processes underpinning performance, some relating it to the concept of working memory and proposing a crucial role for the central executive, with the nature of other components currently unclear. Up to this point, virtually all work has been based on correlational analysis of number of correct solutions, sometimes related to possible strategies. We explore the application to this problem of the concurrent task methodology used widely in developing the concept of multicomponent working memory. Participants attempted to solve problems from the matrices under baseline conditions, or accompanied by backward counting or verbal repetition tasks, assumed to disrupt the central executive and phonological loop components of working memory, respectively. As in other uses of this method, number of items correct showed little effect, while solution time measures gave very clear evidence of an important role for the central executive, but no evidence for phonological loop involvement. We conclude that this and related concurrent task techniques hold considerable promise for the analysis of Raven's matrices and potentially for other established psychometric tests.

  16. Dynamic coupling of complex brain networks and dual-task behavior.

    PubMed

    Alavash, Mohsen; Thiel, Christiane M; Gießing, Carsten

    2016-04-01

    Multi-tasking is a familiar situation where behavioral performance is often challenged. To date, fMRI studies investigating the neural underpinning of dual-task interference have mostly relied on local brain activation maps or static brain connectivity networks. Here, based on task fMRI we explored how fluctuations in behavior during concurrent performance of a visuospatial and a speech task relate to alternations in the topology of dynamic brain connectivity networks. We combined a time-resolved functional connectivity and complex network analysis with a sliding window approach applied to the trial by trial behavioral responses to investigate the coupling between dynamic brain networks and dual-task behavior at close temporal proximity. Participants showed fluctuations in their dual-task behavior over time, with the accuracy in the component tasks being statistically independent from one another. On the global level of brain networks we found that dynamic changes of network topology were differentially coupled with the behavior in each component task during the course of dual-tasking. While momentary decrease in the global efficiency of dynamic brain networks correlated with subsequent increase in visuospatial accuracy, better speech performance was preceded by higher global network efficiency and was followed by an increase in between-module connectivity over time. Additionally, dynamic alternations in the modular organization of brain networks at the posterior cingulate cortex were differentially predictive for the visuospatial as compared to the speech accuracy over time. Our results provide the first evidence that, during the course of dual-tasking, each component task is supported by a distinct topological configuration of brain connectivity networks. This finding suggests that the failure of functional brain connectivity networks to adapt to an optimal topology supporting the performance in both component tasks at the same time contributes to the moment to

  17. Influence of dual-task on sit-to-stand-to-sit postural control in Parkinson's disease.

    PubMed

    Fernandes, Ângela; Sousa, Andreia S P; Couras, Joana; Rocha, Nuno; Tavares, João Manuel R S

    2015-11-01

    Postural control deficits are the most disabling aspects of Parkinson's disease (PD), resulting in decreased mobility and functional independence. The aim of this study was to assess the postural control stability, revealed by variables based on the centre of pressure (CoP), in individuals with PD while performing a sit-to-stand-to-sit sequence under single- and dual-task conditions. An observational, analytical and cross-sectional study was performed. The sample consisted of 9 individuals with PD and 9 healthy controls. A force platform was used to measure the CoP displacement and velocity during the sit-to-stand-to-sit sequence. The results were statistically analysed. Individuals with PD required greater durations for the sit-to-stand-to-sit sequence than the controls (p < 0.05). The anteroposterior and mediolateral CoP displacement were higher in the individuals with PD (p < 0.05). However, only the anteroposterior CoP velocity in the stand-to-sit phase (p = 0.006) was lower in the same individuals. Comparing the single- and dual-task conditions in both groups, the duration, the anteroposterior CoP displacement and velocity were higher in the dual-task condition (p < 0.05). The individuals with PD presented reduced postural control stability during the sit-to-stand-to-sit sequence, especially when under the dual-task condition. These individuals have deficits not only in motor performance, but also in cognitive performance when performing the sit-to-stand-to-sit sequence in their daily life tasks. Moreover, both deficits tend to be intensified when two tasks are performed simultaneously.

  18. Parkinson's Disease and Cognitive-Motor Dual-Task: Is Motor Prioritization Possible in the Early Stages of the Disease?

    PubMed

    Fernandes, Ângela; Sousa, Andreia S P; Rocha, Nuno; Tavares, João Manuel R S

    2016-01-01

    The authors aimed to compare the postural phase of gait initiation under single-task (gait initiation) and dual-task (gait initiation plus Stroop test) conditions in healthy subjects and in subjects with Parkinson's disease (PD) in the early stages (Hoehn and Yahr scale < 3). The postural phase of gait initiation was assessed through the centre of pressure in single and dual task in 10 healthy subjects and 9 with PD. The analysis indicated that in the early stages of PD, an additional cognitive task did not affect the displacement of the gait initiation. No significant effects occurred between the groups and within-subjects (p > .05). Also, no interaction was found between the groups and the conditions (single- and dual-task). Differences were found in the duration of the mediolateral postural phase (p = .003), which was higher in PD subjects than in healthy subjects. The findings suggest that subjects in the early stages of PD prioritize gait initiation, as their motor performance was similar to that of healthy subjects. PMID:27159414

  19. Analysis of dual-task elderly gait in fallers and non-fallers using wearable sensors.

    PubMed

    Howcroft, Jennifer; Kofman, Jonathan; Lemaire, Edward D; McIlroy, William E

    2016-05-01

    Dual-task (DT) gait involves walking while simultaneously performing an attention-demanding task and can be used to identify impaired gait or executive function in older adults. Advancment is needed in techniques that quantify the influence of dual tasking to improve predictive and diagnostic potential. This study investigated the viability of wearable sensor measures to identify DT gait changes in older adults and distinguish between elderly fallers and non-fallers. A convenience sample of 100 older individuals (75.5±6.7 years; 76 non-fallers, 24 fallers based on 6 month retrospective fall occurrence) walked 7.62m under single-task (ST) and DT conditions while wearing pressure-sensing insoles and tri-axial accelerometers at the head, pelvis, and left and right shanks. Differences between ST and DT gait were identified for temporal measures, acceleration descriptive statistics, Fast Fourier Transform (FFT) quartiles, ratio of even to odd harmonics, center of pressure (CoP) stance path coefficient of variation, and deviations to expected CoP stance path. Increased posterior CoP stance path deviations, increased coefficient of variation, decreased FFT quartiles, and decreased ratio of even to odd harmonics suggested increased DT gait variability. Decreased gait velocity and decreased acceleration standard deviations (SD) at the pelvis and shanks could represent compensatory gait strategies that maintain stability. Differences in acceleration between fallers and non-fallers in head posterior SD and pelvis AP ratio of even to odd harmonics during ST, and pelvis vertical maximum Lyapunov exponent during DT gait were identified. Wearable-sensor-based DT gait assessments could be used in point-of-care environments to identify gait deficits.

  20. Working memory capacity and dual-task interference in picture naming.

    PubMed

    Piai, Vitória; Roelofs, Ardi

    2013-03-01

    Researchers have found no agreement on whether dual-task interference in language performance, such as dual-task interference from tone discrimination on picture naming, reflects passive queuing or active scheduling of processes for each task. According to a passive-queuing account, while a central response-selection bottleneck is occupied by the tone discrimination task, picture naming is held in a passive queue until the bottleneck is freed. In contrast, according to an active-scheduling account, participants determine the order in which the tasks proceed, monitor progress on the tasks, suspend picture naming and hold it in working memory, and determine when to resume picture naming. Here, we report a study that assessed the relative merits of the queuing and scheduling accounts by examining whether the magnitude of dual-task interference in picture naming is associated with individual differences in the capacity of monitoring and updating of working memory representations, as assessed by the operation-span task. We observed that the updating/monitoring ability correlated with the speed of picture naming and with the magnitude of the interference from tone discrimination on picture naming. These results lend support to the active-scheduling account of dual-task interference in picture naming.

  1. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk.

    PubMed

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task-an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias. PMID:27605922

  2. Does Working Memory Enhance or Interfere with Speech Fluency in Adults Who Do and Do Not Stutter? Evidence from a Dual-Task Paradigm

    ERIC Educational Resources Information Center

    Eichorn, Naomi; Marton, Klara; Schwartz, Richard G.; Melara, Robert D.; Pirutinsky, Steven

    2016-01-01

    Purpose: The present study examined whether engaging working memory in a secondary task benefits speech fluency. Effects of dual-task conditions on speech fluency, rate, and errors were examined with respect to predictions derived from three related theoretical accounts of disfluencies. Method: Nineteen adults who stutter and twenty adults who do…

  3. An auditory display in a dual-axis tracking task.

    NASA Technical Reports Server (NTRS)

    Mirchandani, P. B.

    1972-01-01

    Results of a study in which subjects were presented concurrently with the primary task of controlling a second-order plant and the secondary task of controlling a first-order plant. The plant errors for the two tasks were shown on separate visual displays. An auditory display, whose output varied in frequency and volume with the error, was used to supplement the secondary task in half of the runs. To study the effects of the auditory display, two performance measures were obtained: (1) the integral of the squared error (ISE) and (2) the describing functions of the human operator. Statistical analysis of the ISE measures indicated that when the secondary task was supplemented with an auditory display, there was a significant improvement in performance on the secondary task. The performance on the primary task improved on the average, but not significantly. The variances of the ISE values decreased for both the tasks, indicating a more consistent behavior with the auditory display. The describing function analysis showed that supplementing the secondary task with the auditory display increased the low frequency gain of the human operator for this task. The describing functions for the primary task did not show any apparent changes.

  4. Dual-Task Interference during Initial Learning of a New Motor Task Results from Competition for the Same Brain Areas

    ERIC Educational Resources Information Center

    Remy, Florence; Wenderoth, Nicole; Lipkens, Karen; Swinnen, Stephan P.

    2010-01-01

    Cerebral patterns of activity elicited by dual-task performance throughout the learning of a complex bimanual coordination pattern were addressed. Subjects (N = 12) were trained on the coordination pattern and scanned using fMRI at early (PRE) and late (POST) learning stages. During scanning, the coordination pattern was performed either as a…

  5. Dual-goal facilitation in Wason's 2-4-6 task: what mediates successful rule discovery?

    PubMed

    Gale, Maggie; Ball, Linden J

    2006-05-01

    The standard 2-4-6 task requires discovery of a single rule and produces success rates of about 20%, whereas the dual-goal (DG) version requests discovery of two complementary rules and elevates success to over 60%. The experiment examined two explanations of DG superiority: Evans' (1989) positivity-bias account, and Wharton, Cheng, and Wickens' (1993) goal-complementarity theory. Two DG conditions were employed that varied the linguistic labelling of rules (either positively labelled Dax vs. Med, or mixed-valence "fits" vs. "does not fit"). Solution-success results supported the goal-complementarity theory since facilitation arose in both DG conditions relative to single-goal tasks, irrespective of the linguistic labelling of hypotheses. DG instructions also altered quantitative and qualitative aspects of hypothesis-testing behaviour, and analyses revealed the novel result that the production of at least a single descending triple mediates between DG instructions and task success. We propose that the identification of an appropriate contrast class that delimits the scope of complementary rules may be facilitated through the generation of a descending instance. Overall, our findings can best be accommodated by Oaksford and Chater's (1994) iterative counterfactual model of hypotheses testing, which can readily subsume key elements of the goal-complementarity theory. PMID:16608752

  6. Free-Throw Shooting during Dual-Task Performance: Implications for Attentional Demand and Performance

    ERIC Educational Resources Information Center

    Price, Jayme; Gill, Diane L.; Etnier, Jennifer; Kornatz, Kurt

    2009-01-01

    In this study, the dual-task paradigm was used to determine peak attentional demand during the free-throw process. Thirty participants completed 40 free-throw trials. The free throw was the primary task, but participants also verbally responded to a tone administered at one of four probe positions (PP). Repeated measures analysis of variance…

  7. Comparison of Psychophysiological and Dual-Task Measures of Listening Effort

    ERIC Educational Resources Information Center

    Seeman, Scott; Sims, Rebecca

    2015-01-01

    Purpose: We wished to make a comparison of psychophysiological measures of listening effort with subjective and dual-task measures of listening effort for a diotic-dichotic-digits and a sentences-in-noise task. Method: Three groups of young adults (18-38 years old) with normal hearing participated in three experiments: two psychophysiological…

  8. Speech responses and dual-task performance - Better time-sharing or asymmetric transfer?

    NASA Technical Reports Server (NTRS)

    Vidulich, Michael A.

    1988-01-01

    The value of speech controls in a dual-task experiment that also evaluated asymmetric transfer effects is considered. There was no evidence of asymmetric transfer in spite of significant effects supporting the advantage of mixing manual and speech responses. The data suggest that speech controls can be used to enhance performance in operational multiple-task environments.

  9. Dual-arm supervisory and shared control space servicing task experiments

    NASA Technical Reports Server (NTRS)

    Backes, Paul G.

    1992-01-01

    A dual-arm task execution primitive has been implemented for cooperative dual-arm telerobotic task execution utilizing multiple sensors concurrently. The primitive has been integrated into a telerobot task execution system and can be called by a task planning system for execution of tasks requiring dual-arm sensor based motion, e.g., force control, teleoperation, and shared control. The primitive has a large input parameter set which is used to specify the desired behavior of the motion. Move-squeeze decomposition is utilized to decompose forces sensed at the wrists of the two manipulators into forces in the move subspace, which cause system motion, and forces in the squeeze subspaces, which cause internal forces. The move and squeeze forces are then separately controlled. Several space servicing tasks utilizing the cooperative dual-arm control capability are described, and experimental results from the tasks are given. The supervisory and shared control tasks include capture of a rotating satellite, orbital replacement unit changeout, fluid coupler seating and locking, and contour following.

  10. Using Dual-Task Methodology to Dissociate Automatic from Nonautomatic Processes Involved in Artificial Grammar Learning

    ERIC Educational Resources Information Center

    Hendricks, Michelle A.; Conway, Christopher M.; Kellogg, Ronald T.

    2013-01-01

    Previous studies have suggested that both automatic and intentional processes contribute to the learning of grammar and fragment knowledge in artificial grammar learning (AGL) tasks. To explore the relative contribution of automatic and intentional processes to knowledge gained in AGL, we utilized dual-task methodology to dissociate automatic and…

  11. The Neurocognitive Basis for Impaired Dual-Task Performance in Senior Fallers

    PubMed Central

    Nagamatsu, Lindsay S.; Hsu, C. Liang; Voss, Michelle W.; Chan, Alison; Bolandzadeh, Niousha; Handy, Todd C.; Graf, Peter; Beattie, B. Lynn; Liu-Ambrose, Teresa

    2016-01-01

    Falls are a major health-care concern, and while dual-task performance is widely recognized as being impaired in those at-risk for falls, the underlying neurocognitive mechanisms remain unknown. A better understanding of the underlying mechanisms could lead to the refinement and development of behavioral, cognitive, or neuropharmacological interventions for falls prevention. Therefore, we conducted a cross-sectional study with community-dwelling older adults aged 70–80 years with a history of falls (i.e., two or more falls in the past 12 months) or no history of falls (i.e., zero falls in the past 12 months); n = 28 per group. We compared functional activation during cognitive-based dual-task performance between fallers and non-fallers using functional magnetic resonance imaging (fMRI). Executive cognitive functioning was assessed via Stroop, Trail Making, and Digit Span. Mobility was assessed via the Timed Up and Go test (TUG). We found that non-fallers exhibited significantly greater functional activation compared with fallers during dual-task performance in key regions responsible for resolving dual-task interference, including precentral, postcentral, and lingual gyri. Further, we report slower reaction times during dual-task performance in fallers and significant correlations between level of functional activation and independent measures of executive cognitive functioning and mobility. Our study is the first neuroimaging study to examine dual-task performance in fallers, and supports the notion that fallers have reduced functional brain activation compared with non-fallers. Given that dual-task performance—and the underlying neural concomitants—appears to be malleable with relevant training, our study serves as a launching point for promising strategies to reduce falls in the future. PMID:26903862

  12. A new quantitative method for evaluating freezing of gait and dual-attention task deficits in Parkinson's disease.

    PubMed

    Chomiak, Taylor; Pereira, Fernando Vieira; Meyer, Nicole; de Bruin, Natalie; Derwent, Lorelei; Luan, Kailie; Cihal, Alexandra; Brown, Lesley A; Hu, Bin

    2015-11-01

    People with Parkinson's disease (PD) can exhibit disabling gait symptoms such as freezing of gait especially when distracted by a secondary task. Quantitative measurement method of this type of cognitive-motor abnormality, however, remains poorly developed. Here we examined whether stepping-in-place (SIP) with a concurrent mental task (e.g., subtraction) can be used as a simple method for evaluating cognitive-motor deficits in PD. We used a 4th generation iPod Touch sensor system to capture hip flexion data and obtain step height (SH) measurements (z axis). The accuracy of the method was compared to and validated by kinematic video analysis software. We found a general trend of reduced SH for PD subjects relative to controls under all conditions. However, the SH of PD freezers was significantly worse than PD non-freezers and controls during concurrent serial 7 subtraction and SIP tasking. During serial 7 subtraction, SH was significantly associated with whether or not a PD patient was a self-reported freezer even when controlling for disease severity. Given that this SIP-based dual-task paradigm is not limited by space requirements and can be quantified using a mobile tracking device that delivers specifically designed auditory task instructions, the method reported here may be used to standardize clinical assessment of cognitive-motor deficits under a variety of dual-task conditions in PD. PMID:26206604

  13. A new quantitative method for evaluating freezing of gait and dual-attention task deficits in Parkinson's disease.

    PubMed

    Chomiak, Taylor; Pereira, Fernando Vieira; Meyer, Nicole; de Bruin, Natalie; Derwent, Lorelei; Luan, Kailie; Cihal, Alexandra; Brown, Lesley A; Hu, Bin

    2015-11-01

    People with Parkinson's disease (PD) can exhibit disabling gait symptoms such as freezing of gait especially when distracted by a secondary task. Quantitative measurement method of this type of cognitive-motor abnormality, however, remains poorly developed. Here we examined whether stepping-in-place (SIP) with a concurrent mental task (e.g., subtraction) can be used as a simple method for evaluating cognitive-motor deficits in PD. We used a 4th generation iPod Touch sensor system to capture hip flexion data and obtain step height (SH) measurements (z axis). The accuracy of the method was compared to and validated by kinematic video analysis software. We found a general trend of reduced SH for PD subjects relative to controls under all conditions. However, the SH of PD freezers was significantly worse than PD non-freezers and controls during concurrent serial 7 subtraction and SIP tasking. During serial 7 subtraction, SH was significantly associated with whether or not a PD patient was a self-reported freezer even when controlling for disease severity. Given that this SIP-based dual-task paradigm is not limited by space requirements and can be quantified using a mobile tracking device that delivers specifically designed auditory task instructions, the method reported here may be used to standardize clinical assessment of cognitive-motor deficits under a variety of dual-task conditions in PD.

  14. Dual-task related gait changes after CSF tapping: a new way to identify idiopathic normal pressure hydrocephalus

    PubMed Central

    2013-01-01

    Background Gait disturbances found in patients with idiopathic normal pressure hydrocephalus (iNPH) are unspecific to the diagnosis and commonly occur in neurodegenerative or vascular conditions (iNPH-like conditions). This current retrospective pre-post intervention study aims to determine whether changes in quantitative gait parameters during dual task condition differed between iNPH and iNPH-like conditions before and after cerebrospinal fluid (CSF) tapping. Methods 49 patients assessed before and after CSF tapping were included in this study (27 with iNPH and 22 with iNPH-like conditions). Gait analysis during single and dual task conditions (walking and backward counting) was performed before and after a CSF spinal tap of 40 ml. Gait parameters were compared between iNPH and iNPH-like conditions patients. Logistic regressions were used to examine the association between iNPH and gait parameters. Results Improvements of step width (−9.03 (20.75)% for iNPH group; +0.28 (21.76)% for iNPH-like conditions group), stride length (+7.82 (20.71)% for iNPH group; -0.62 (19.22)% for iNPH-like conditions group), walking speed (+12.20 (29.79)% for iNPH group; +2.38 (32.50)% for iNPH-like conditions group) and stance duration (−1.23 (4.03)% for iNPH group; +0.49 (5.12)% for iNPH-like conditions group) during dual task, after CSF spinal tapping, were significant in patients with iNPH compared to patients with iNPH-like conditions. No between group difference was observed for the single walking task evaluation. The multiple logistic regression revealed that among these four gait parameters, only the improvement in step width was associated with the diagnosis of iNPH. Conclusion Dual-task related changes in spatio-temporal gait parameters before and after CSF tapping might be a novel and discriminative method of identifying iNPH patients from other similar conditions. PMID:24359487

  15. A Task that Elicits Reasoning: A Dual Analysis

    ERIC Educational Resources Information Center

    Yankelewitz, Dina; Mueller, Mary; Maher, Carolyn A.

    2010-01-01

    This paper reports on the forms of reasoning elicited as fourth grade students in a suburban district and sixth grade students in an urban district worked on similar tasks involving reasoning with the use of Cuisenaire rods. Analysis of the two data sets shows similarities in the reasoning used by both groups of students on specific tasks, and the…

  16. Dual Tasking for the Differentiation between Depression and Mild Cognitive Impairment

    PubMed Central

    Metzger, Florian G.; Hobert, Markus A.; Ehlis, Ann-Christine; Hasmann, Sandra E.; Hahn, Tim; Eschweiler, Gerhard W.; Berg, Daniela; Fallgatter, Andreas J.; Maetzler, Walter

    2016-01-01

    Differentiation of mild cognitive impairment from depression in elderly adults is a clinically relevant issue which is not sufficiently solved. Gait and dual task (DT) parameters may have the potential to complement current diagnostic work-up, as both dementia and depression are associated with changes of gait and DT parameters. Methods: Seven hundred and four participants of the TREND study (Tübinger evaluation of Risk factors for Early detection of NeuroDegeneration) aged 50–80 years were assessed using the Consortium to Establish a Registry for Alzheimer's Disease Plus test battery for testing cognition and Beck's Depression Inventory for evaluation of depression. Based on these results, four groups were defined: acute depressed (N = 53), cognitively mildly impaired (N = 97), acute depressed, and cognitively mildly impaired (N = 15), and controls (N = 536). Participants underwent a 20 m walk and checking boxes task under single (ST) and DT conditions. ST and DT performance and dual task costs (DTC) were calculated. Due to the typical age of increasing incidence of depressive and also cognitive symptoms, the 7th decade was calculated separately. Results: ST speeds of gait and checking boxes, DT walking speed, and walking DTC were significantly different between groups. Healthy controls were the fastest in all paradigms and cognitively mildly impaired had higher DTC than depressed individuals. Additionally, we constructed a multivariate predictive model differentiating the groups on a single-subject level. Conclusion: DT parameters are simply and comfortably measureable, and DTC can easily be determined. The combination of these parameters allows a differentiation of depressed and cognitively mildly impaired elderly adults. PMID:27790136

  17. Postural Control in Dual-Task Situations: Does Whole-Body Fatigue Matter?

    PubMed Central

    Beurskens, Rainer; Haeger, Matthias; Kliegl, Reinhold; Roecker, Kai; Granacher, Urs

    2016-01-01

    Postural control is important to cope with demands of everyday life. It has been shown that both attentional demand (i.e., cognitive processing) and fatigue affect postural control in young adults. However, their combined effect is still unresolved. Therefore, we investigated the effects of fatigue on single- (ST) and dual-task (DT) postural control. Twenty young subjects (age: 23.7 ± 2.7) performed an all-out incremental treadmill protocol. After each completed stage, one-legged-stance performance on a force platform under ST (i.e., one-legged-stance only) and DT conditions (i.e., one-legged-stance while subtracting serial 3s) was registered. On a second test day, subjects conducted the same balance tasks for the control condition (i.e., non-fatigued). Results showed that heart rate, lactate, and ventilation increased following fatigue (all p < 0.001; d = 4.2–21). Postural sway and sway velocity increased during DT compared to ST (all p < 0.001; d = 1.9–2.0) and fatigued compared to non-fatigued condition (all p < 0.001; d = 3.3–4.2). In addition, postural control deteriorated with each completed stage during the treadmill protocol (all p < 0.01; d = 1.9–3.3). The addition of an attention-demanding interference task did not further impede one-legged-stance performance. Although both additional attentional demand and physical fatigue affected postural control in healthy young adults, there was no evidence for an overadditive effect (i.e., fatigue-related performance decrements in postural control were similar under ST and DT conditions). Thus, attentional resources were sufficient to cope with the DT situations in the fatigue condition of this experiment. PMID:26796320

  18. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk

    PubMed Central

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S.

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task—an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias.

  19. Inhibitory processes relate differently to balance/reaction time dual tasks in young and older adults

    PubMed Central

    Mendelson, David N.; Redfern, Mark S.; Nebes, Robert D.; Jennings, J. Richard

    2016-01-01

    Inhibitory processes have been suggested to be involved in maintaining balance in older adults, specifically in the integration of sensory information. This study investigated the association between inhibition and the ability to shift attention between auditory and visual modalities during a balance challenge. Young (21–35 yrs; n=24) and older (70–85 yrs; n=22) healthy subjects completed tasks assessing perceptual inhibition and motor inhibition. Subjects then performed dual-task paradigms pairing auditory and visual choice reaction time tasks with different postural conditions. Sensory channel switch cost was quantified as the difference between visual and auditory reaction times. Results showed that better perceptual and motor inhibition capabilities were associated with less sensory switch cost in the old (perceptual inhibition: r=0.51; motor inhibition: r=0.48). In the young, neither perceptual nor motor inhibition was associated with sensory switch cost. Inhibitory skills appear particularly important in the elderly for processing events from multiple sensory channels while maintaining balance. PMID:19526388

  20. High-Frequency Binaural Beats Increase Cognitive Flexibility: Evidence from Dual-Task Crosstalk

    PubMed Central

    Hommel, Bernhard; Sellaro, Roberta; Fischer, Rico; Borg, Saskia; Colzato, Lorenza S.

    2016-01-01

    Increasing evidence suggests that cognitive-control processes can be configured to optimize either persistence of information processing (by amplifying competition between decision-making alternatives and top-down biasing of this competition) or flexibility (by dampening competition and biasing). We investigated whether high-frequency binaural beats, an auditory illusion suspected to act as a cognitive enhancer, have an impact on cognitive-control configuration. We hypothesized that binaural beats in the gamma range bias the cognitive-control style toward flexibility, which in turn should increase the crosstalk between tasks in a dual-task paradigm. We replicated earlier findings that the reaction time in the first-performed task is sensitive to the compatibility between the responses in the first and the second task—an indication of crosstalk. As predicted, exposing participants to binaural beats in the gamma range increased this effect as compared to a control condition in which participants were exposed to a continuous tone of 340 Hz. These findings provide converging evidence that the cognitive-control style can be systematically biased by inducing particular internal states; that high-frequency binaural beats bias the control style toward more flexibility; and that different styles are implemented by changing the strength of local competition and top-down bias. PMID:27605922

  1. Gait Adaptability Training Improves Both Postural Stability and Dual-Tasking Ability

    NASA Technical Reports Server (NTRS)

    Brady, Rachel A.; Batson, Crystal D.; Peters, Brian T.; Ploutz-Snyder, Robert J.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.

    2010-01-01

    After spaceflight, the process of readapting to Earth's gravity commonly presents crewmembers with a variety of locomotor challenges. Our recent work has shown that the ability to adapt to a novel discordant sensorimotor environment can be increased through preflight training, so one focus of our laboratory has been the development of a gait training countermeasure to expedite the return of normal locomotor function after spaceflight. We used a training system comprising a treadmill mounted on a motion base facing a virtual visual scene that provided a variety of sensory challenges. As part of their participation in a larger retention study, 10 healthy adults completed 3 training sessions during which they walked on a treadmill at 1.1 m/s while receiving discordant support-surface and visual manipulations. After a single training session, subjects stride frequencies improved, and after 2 training sessions their auditory reaction times improved, where improvement was indicated by a return toward baseline values. Interestingly, improvements in reaction time came after stride frequency improvements plateaued. This finding suggests that postural stability was given a higher priority than a competing cognitive task. Further, it demonstrates that improvement in both postural stability and dual-tasking can be achieved with multiple training exposures. We conclude that, with training, individuals become more proficient at walking in discordant sensorimotor conditions and are able to devote more attention to competing tasks.

  2. Corticospinal activity during dual tasking: a systematic review and meta-analysis of TMS literature from 1995 to 2013.

    PubMed

    Corp, Daniel T; Lum, Jarrad A G; Tooley, Gregory A; Pearce, Alan J

    2014-06-01

    This systematic review and meta-analysis was conducted across studies using transcranial magnetic stimulation to investigate corticospinal excitability and inhibition in response to a dual task (DT). Quantitative analysis was performed on eleven controlled studies that had included healthy participants over the age of 18 years. Results showed a small effect size for increased corticospinal excitability for DT conditions (SMD=0.207; p=.217, and a small effect size (SMD=-0.253) demonstrating a significant decrease in corticospinal inhibition for DT conditions (p=.019). Meta-regression demonstrated that neither age, task type, or task prioritisation accounted for the high variability in effect sizes between studies. A number of possible sources of within study bias are identified, which reduced the level of evidence for study findings. The results show overall changes in corticospinal responses between ST and DT conditions; however further research is necessary to investigate variables that could account for differences in corticospinal responses between studies. PMID:24705270

  3. Simultaneous dual-task performance reveals parallel response selection after practice

    NASA Technical Reports Server (NTRS)

    Hazeltine, Eliot; Teague, Donald; Ivry, Richard B.

    2002-01-01

    E. H. Schumacher, T. L. Seymour, J. M. Glass, D. E. Kieras, and D. E. Meyer (2001) reported that dual-task costs are minimal when participants are practiced and give the 2 tasks equal emphasis. The present research examined whether such findings are compatible with the operation of an efficient response selection bottleneck. Participants trained until they were able to perform both tasks simultaneously without interference. Novel stimulus pairs produced no reaction time costs, arguing against the development of compound stimulus-response associations (Experiment 1). Manipulating the relative onsets (Experiments 2 and 4) and durations (Experiments 3 and 4) of response selection processes did not lead to dual-task costs. The results indicate that the 2 tasks did not share a bottleneck after practice.

  4. Driven to distraction: dual-Task studies of simulated driving and conversing on a cellular telephone.

    PubMed

    Strayer, D L; Johnston, W A

    2001-11-01

    Dual-task studies assessed the effects of cellular-phone conversations on performance of a simulated driving task. Performance was not disrupted by listening to radio broadcasts or listening to a book on tape. Nor was it disrupted by a continuous shadowing task using a handheld phone, ruling out, in this case, dual-task interpretations associated with holding the phone, listening, or speaking, However significant interference was observed in a word-generation variant of the shadowing task, and this deficit increased with the difficulty of driving. Moreover unconstrained conversations using either a handheld or a hands-free cell phone resulted in a twofold increase in the failure to detect simulated traffic signals and slower reactions to those signals that were detected. We suggest that cellular-phone use disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving. PMID:11760132

  5. E-learning, dual-task, and cognitive load: The anatomy of a failed experiment.

    PubMed

    Van Nuland, Sonya E; Rogers, Kem A

    2016-01-01

    The rising popularity of commercial anatomy e-learning tools has been sustained, in part, due to increased annual enrollment and a reduction in laboratory hours across educational institutions. While e-learning tools continue to gain popularity, the research methodologies used to investigate their impact on learning remain imprecise. As new user interfaces are introduced, it is critical to understand how functionality can influence the load placed on a student's memory resources, also known as cognitive load. To study cognitive load, a dual-task paradigm wherein a learner performs two tasks simultaneously is often used, however, its application within educational research remains uncommon. Using previous paradigms as a guide, a dual-task methodology was developed to assess the cognitive load imposed by two commercial anatomical e-learning tools. Results indicate that the standard dual-task paradigm, as described in the literature, is insensitive to the cognitive load disparities across e-learning tool interfaces. Confounding variables included automation of responses, task performance tradeoff, and poor understanding of primary task cognitive load requirements, leading to unreliable quantitative results. By modifying the secondary task from a basic visual response to a more cognitively demanding task, such as a modified Stroop test, the automation of secondary task responses can be reduced. Furthermore, by recording baseline measures for the primary task as well as the secondary task, it is possible for task performance tradeoff to be detected. Lastly, it is imperative that the cognitive load of the primary task be designed such that it does not overwhelm the individual's ability to learn new material.

  6. Decision and Response in Dual-Task Interference

    PubMed

    Van Selst M; Jolicoeur

    1997-08-01

    Experiments with two stimuli (S1 and S2) and two responses suggest the existence of a stage of processing that cannot be shared between two concurrent tasks. Widespread support has been found for the hypothesis that response selection for Task2 is postponed when the S1 to S2 stimulus onset asynchrony (SOA) is short (Pashler, 1994a). At short SOAs, manipulations which impact Task2 processing prior to response selection (e.g., degradation of stimulus quality) have little effect on Task2 response times (RTs). On the other hand, manipulations which are thought to impact response selection or execution (e.g., Stroop interference) always impact Task2 RTs. There is, however, one particularly compelling demonstration that appears to be inconsistent with the response selection bottleneck hypothesis: Karlin and Kestenbaum (1968) report that the RT difference between detection (i.e., 1-choice) and 2-choice discrimination dramatically decreases with decreasing SOA. Given that the primary difference between detection and discrimination is believed to be at response selection, their result may indicate a processing bottleneck at response execution (Keele, 1973). We fail to replicate the Karlin and Kestenbaum result in two substantive replications of Karlin and Kestenbaum's tasks and procedures. In the single experiment in which Karlin and Kestenbaum's result is replicated, a simple response execution bottleneck account is ruled out by the stability of the difference between 2-choice and 3-choice discrimination times across SOA. Two additional experiments demonstrate that response preparation and task strategy do not substantially contribute to the attenuation of response selection-level effects with decreasing SOA.

  7. Dual-Task Processing in Younger and Older Adults: Similarities and Differences Revealed by fMRI

    ERIC Educational Resources Information Center

    Hartley, Alan A.; Jonides, John; Sylvester, Ching-Yune C.

    2011-01-01

    fMRI was used to explore age differences in the neural substrate of dual-task processing. Brain activations when there was a 100 ms SOA between tasks, and task overlap was high, were contrasted with activations when there was a 1000 ms SOA, and first task processing was largely complete before the second task began. Younger adults (M = 21 yrs)…

  8. Central as well as Peripheral Attentional Bottlenecks in Dual-Task Performance Activate Lateral Prefrontal Cortices

    PubMed Central

    Szameitat, André J.; Vanloo, Azonya; Müller, Hermann J.

    2016-01-01

    Human information processing suffers from severe limitations in parallel processing. In particular, when required to respond to two stimuli in rapid succession, processing bottlenecks may appear at central and peripheral stages of task processing. Importantly, it has been suggested that executive functions are needed to resolve the interference arising at such bottlenecks. The aims of the present study were to test whether central attentional limitations (i.e., bottleneck at the decisional response selection stage) as well as peripheral limitations (i.e., bottleneck at response initiation) both demand executive functions located in the lateral prefrontal cortex. For this, we re-analyzed two previous studies, in which a total of 33 participants performed a dual-task according to the paradigm of the psychological refractory period (PRP) during functional magnetic resonance imaging (fMRI). In one study (N = 17), the PRP task consisted of two two-choice response tasks known to suffer from a central bottleneck (CB group). In the other study (N = 16), the PRP task consisted of two simple-response tasks known to suffer from a peripheral bottleneck (PB group). Both groups showed considerable dual-task costs in form of slowing of the second response in the dual-task (PRP effect). Imaging results are based on the subtraction of both single-tasks from the dual-task within each group. In the CB group, the bilateral middle frontal gyri and inferior frontal gyri were activated. Higher activation in these areas was associated with lower dual-task costs. In the PB group, the right middle frontal and inferior frontal gyrus (IFG) were activated. Here, higher activation was associated with higher dual-task costs. In conclusion we suggest that central and peripheral bottlenecks both demand executive functions located in lateral prefrontal cortices (LPFC). Differences between the CB and PB groups with respect to the exact prefrontal areas activated and the correlational patterns

  9. Central as well as Peripheral Attentional Bottlenecks in Dual-Task Performance Activate Lateral Prefrontal Cortices.

    PubMed

    Szameitat, André J; Vanloo, Azonya; Müller, Hermann J

    2016-01-01

    Human information processing suffers from severe limitations in parallel processing. In particular, when required to respond to two stimuli in rapid succession, processing bottlenecks may appear at central and peripheral stages of task processing. Importantly, it has been suggested that executive functions are needed to resolve the interference arising at such bottlenecks. The aims of the present study were to test whether central attentional limitations (i.e., bottleneck at the decisional response selection stage) as well as peripheral limitations (i.e., bottleneck at response initiation) both demand executive functions located in the lateral prefrontal cortex. For this, we re-analyzed two previous studies, in which a total of 33 participants performed a dual-task according to the paradigm of the psychological refractory period (PRP) during functional magnetic resonance imaging (fMRI). In one study (N = 17), the PRP task consisted of two two-choice response tasks known to suffer from a central bottleneck (CB group). In the other study (N = 16), the PRP task consisted of two simple-response tasks known to suffer from a peripheral bottleneck (PB group). Both groups showed considerable dual-task costs in form of slowing of the second response in the dual-task (PRP effect). Imaging results are based on the subtraction of both single-tasks from the dual-task within each group. In the CB group, the bilateral middle frontal gyri and inferior frontal gyri were activated. Higher activation in these areas was associated with lower dual-task costs. In the PB group, the right middle frontal and inferior frontal gyrus (IFG) were activated. Here, higher activation was associated with higher dual-task costs. In conclusion we suggest that central and peripheral bottlenecks both demand executive functions located in lateral prefrontal cortices (LPFC). Differences between the CB and PB groups with respect to the exact prefrontal areas activated and the correlational patterns

  10. The Effect of Various Dual Task Training Methods with Gait on the Balance and Gait of Patients with Chronic Stroke

    PubMed Central

    An, Ho-Jung; Kim, Jae-Ic; Kim, Yang-Rae; Lee, Kyoung-Bo; Kim, Dai-Joong; Yoo, Kyung-Tae; Choi, Jung-Hyun

    2014-01-01

    [Purpose] This study examined the effects of various dual task gait training methods (motor dual task gait training, cognitive dual task gait training, and motor and cognitive dual task gait training) on the balance and gait abilities of chronic stroke patients. [Subjects and Methods] Thirty-three outpatients performed dual task gait training for 30 minutes per day, three times a week, for eight weeks from June to August, 2012. Balance ability was measured pre-and posttest using the stability test index, the weight distribution index, the functional reach test, the timed up and go test, and the four square step test. Gait ability was measured by the 10 m walk test and a 6 min walk test before and after the training. The paired t-test was used to compare measurements before and after training within each group, and ANOVA was used to compare measurements before and after training among the groups. [Results] Comparisons within each group indicated significant differences in all variables between before and after the training in all three groups. Comparison between the groups showed that the greatest improvements were seen in all tests, except for the timed up and go test, following motor and cognitive dual task gait training. [Conclusion] In a real walking environment, the motor and cognitive dual task gait training was more effective at improving the balance and gait abilities of chronic stroke patients than either the motor dual task gait training or the cognitive dual task gait training alone. PMID:25202199

  11. Effect of methylphenidate on enhancement of spatial learning by novel alternated dual task.

    PubMed

    Veetil, Praveen Kottath; Mukkadan, Joseph Kurian

    2011-01-01

    The novel alternated dual task (ADT) arranged rats to learn T-maze spontaneous alternation task and radial arm maze (RAM) task alternatively, and by doing ADT, rats could acquire the tasks more easily than non alternated dual task (NADT) group. Also retention capacity of ADT group was significantly more and ADT help to learn a complex task faster than learning it in isolation from other tasks. In the present study effect of methylphenidate (MPD), a mood elevator, known to enhance learning and memory, on ADT procedure is assessed. Also effect of ADT procedure and MPD on spatial learning and memory are compared. Different groups were assigned by administering MPD (intraperitoneal injection at a dose of 3 mg/kg body weight) during different phases of behavioural experiments, and control groups received saline injection. MPD administration increased both acquisition and retention capacities. The amelioration attained for retention of complex task by ADT procedure, could be achieved by NADT rats only by administration of MPD. The influence of ADT procedure on acquisition and retention of TM and RAM tasks were similar to the effects of MPD, especially for the RAM task. MPD at low dose is found to enhance the learning and memory capacity in rats, than deteriorating it, supporting the use of MPD as a drug to treat attention deficit hyperactive disorder. The recent reports suggesting the effect of MPD only on retention and not on acquisition could not be confirmed, as enhancement for both acquisition and retention was found in this study. PMID:22319900

  12. Dual design resistor for high voltage conditioning and transmission lines

    DOEpatents

    Siggins, Timothy Lynn; Murray, Charles W.; Walker, Richard L.

    2007-01-23

    A dual resistor for eliminating the requirement for two different value resistors. The dual resistor includes a conditioning resistor at a high resistance value and a run resistor at a low resistance value. The run resistor can travel inside the conditioning resistor. The run resistor is capable of being advanced by a drive assembly until an electrical path is completed through the run resistor thereby shorting out the conditioning resistor and allowing the lower resistance run resistor to take over as the current carrier.

  13. Evidence for a response preparation bottleneck during dual-task performance: effect of a startling acoustic stimulus on the psychological refractory period.

    PubMed

    Maslovat, Dana; Chua, Romeo; Spencer, Hunter C; Forgaard, Christopher J; Carlsen, Anthony N; Franks, Ian M

    2013-11-01

    The present study was designed to investigate the mechanism associated with dual-task interference in a psychological refractory period (PRP) paradigm. We used a simple reaction time paradigm consisting of a vocal response (R1) and key-lift task (R2) with a stimulus onset asynchrony (SOA) between 100ms and 1500ms. On selected trials we implemented a startling acoustic stimulus concurrent with the second stimulus to determine if we could involuntarily trigger the second response. Our results indicated that the PRP delay in the second response was present for both control and startle trials at short SOAs, suggesting the second response was not prepared in advance. These results support a response preparation bottleneck and can be explained via a neural activation model of preparation. In addition, we found that the reflexive startle activation was reduced in the dual-task condition for all SOAs, a result we attribute to prepulse inhibition associated with dual-task processing.

  14. Walking & Talking: Dual-Task Effects on Street Crossing Behavior in Older Adults

    PubMed Central

    Neider, Mark B.; Gaspar, John G.; McCarley, Jason S.; Crowell, James A.; Kaczmarski, Henry; Kramer, Arthur F.

    2013-01-01

    The ability to perform multiple tasks simultaneously has become increasingly important as technologies such as cell phones and portable music players have become more common. In the current study, we examined dual-task costs in older and younger adults using a simulated street crossing task constructed in an immersive virtual environment with an integrated treadmill so that participants could walk as they would in the real world. Participants were asked to cross simulated streets of varying difficulty while either undistracted, listening to music, or conversing on a cell phone. Older adults were more vulnerable to dual-task impairments than younger adults when the crossing task was difficult; dual-task costs were largely absent in the younger adult group. Performance costs in older adults were primarily reflected in timeout rates. When conversing on a cell phone older adults were less likely to complete their crossing compared to when listening to music or undistracted. Analysis of time spent next to the street prior to each crossing, where participants were presumably analyzing traffic patterns and making decisions regarding when to cross, revealed that older adults took longer than younger adults to initiate their crossing, and that this difference was exacerbated during cell phone conversation, suggesting impairments in cognitive planning processes. Our data suggest that multi-tasking costs may be particularly dangerous for older adults even during everyday activities such as crossing the street. PMID:21401262

  15. A Novel Eye-Tracking Method to Assess Attention Allocation in Individuals with and without Aphasia Using a Dual-Task Paradigm

    PubMed Central

    Heuer, Sabine; Hallowell, Brooke

    2015-01-01

    Numerous authors report that people with aphasia have greater difficulty allocating attention than people without neurological disorders. Studying how attention deficits contribute to language deficits is important. However, existing methods for indexing attention allocation in people with aphasia pose serious methodological challenges. Eye-tracking methods have great potential to address such challenges. We developed and assessed the validity of a new dual-task method incorporating eye tracking to assess attention allocation. Twenty-six adults with aphasia and 33 control participants completed auditory sentence comprehension and visual search tasks. To test whether the new method validly indexes well-documented patterns in attention allocation, demands were manipulated by varying task complexity in single- and dual-task conditions. Differences in attention allocation were indexed via eye-tracking measures. For all participants significant increases in attention allocation demands were observed from single- to dual-task conditions and from simple to complex stimuli. Individuals with aphasia had greater difficulty allocating attention with greater task demands. Relationships between eye-tracking indices of comprehension during single and dual tasks and standardized testing were examined. Results support the validity of the novel eye-tracking method for assessing attention allocation in people with and without aphasia. Clinical and research implications are discussed. PMID:25913549

  16. Association between educational status and dual-task performance in young adults.

    PubMed

    Voos, Mariana Callil; Pimentel Piemonte, Maria Elisa; Castelli, Lilian Zanchetta; Andrade Machado, Mariane Silva; Dos Santos Teixeira, Patrícia Pereira; Caromano, Fátima Aparecida; Ribeiro Do Valle, Luiz Eduardo

    2015-04-01

    The influence of educational status on perceptual-motor performance has not been investigated. The single- and dual-task performances of 15 Low educated adults (9 men, 6 women; M age=24.1 yr.; 6-9 yr. of education) and 15 Higher educated adults (8 men, 7 women; M age=24.7 yr.; 10-13 yr. of education) were compared. The perceptual task consisted of verbally classifying two figures (equal or different). The motor task consisted of alternating steps from the floor to a stool. Tasks were assessed individually and simultaneously. Two analyses of variance (2 groups×4 blocks) compared the errors and steps. The Low education group committed more errors and had less improvement on the perceptual task than the High education group. During and after the perceptual-motor task performance, errors increased only in the Low education group. Education correlated to perceptual and motor performance. The Low education group showed more errors and less step alternations on the perceptual-motor task compared to the High education group. This difference on the number of errors was also observed after the dual-task, when the perceptual task was performed alone.

  17. Strategic Adaptation to Task Characteristics, Incentives, and Individual Differences in Dual-Tasking

    PubMed Central

    Janssen, Christian P.; Brumby, Duncan P.

    2015-01-01

    We investigate how good people are at multitasking by comparing behavior to a prediction of the optimal strategy for dividing attention between two concurrent tasks. In our experiment, 24 participants had to interleave entering digits on a keyboard with controlling a randomly moving cursor with a joystick. The difficulty of the tracking task was systematically varied as a within-subjects factor. Participants were also exposed to different explicit reward functions that varied the relative importance of the tracking task relative to the typing task (between-subjects). Results demonstrate that these changes in task characteristics and monetary incentives, together with individual differences in typing ability, influenced how participants choose to interleave tasks. This change in strategy then affected their performance on each task. A computational cognitive model was used to predict performance for a wide set of alternative strategies for how participants might have possibly interleaved tasks. This allowed for predictions of optimal performance to be derived, given the constraints placed on performance by the task and cognition. A comparison of human behavior with the predicted optimal strategy shows that participants behaved near optimally. Our findings have implications for the design and evaluation of technology for multitasking situations, as consideration should be given to the characteristics of the task, but also to how different users might use technology depending on their individual characteristics and their priorities. PMID:26161851

  18. Heating, Ventilation, and Air Conditioning Series. Duty Task List.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This task list is intended for use in planning and/or evaluating a competency-based course in heating, ventilation, and air conditioning. The guide outlines the tasks entailed in eight different duties typically required of employees in the following occupations: residential installer, domestic refrigeration technician, air conditioning and…

  19. Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression

    PubMed Central

    Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel

    2014-01-01

    Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well

  20. Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression.

    PubMed

    Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel

    2013-01-01

    Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well

  1. Short Term Auditory Pacing Changes Dual Motor Task Coordination in Children with and without Dyslexia

    ERIC Educational Resources Information Center

    Getchell, Nancy; Mackenzie, Samuel J.; Marmon, Adam R.

    2010-01-01

    This study examined the effect of short-term auditory pacing practice on dual motor task performance in children with and without dyslexia. Groups included dyslexic with Movement Assessment Battery for Children (MABC) scores greater than 15th percentile (D_HIGH, n = 18; mean age 9.89 [plus or minus] 2.0 years), dyslexic with MABC [less than or…

  2. The Source of Execution-Related Dual-Task Interference: Motor Bottleneck or Response Monitoring?

    ERIC Educational Resources Information Center

    Bratzke, Daniel; Rolke, Bettina; Ulrich, Rolf

    2009-01-01

    The present study assessed the underlying mechanism of execution-related dual-task interference in the psychological refractory period (PRP) paradigm. The motor bottleneck hypothesis attributes this interference to a processing limitation at the motor level. By contrast, the response monitoring hypothesis attributes it to a bottleneck process that…

  3. Locus of Semantic Interference in Picture Naming: Evidence from Dual-Task Performance

    ERIC Educational Resources Information Center

    Piai, Vitória; Roelofs, Ardi; Schriefers, Herbert

    2014-01-01

    Disagreement exists regarding the functional locus of semantic interference of distractor words in picture naming. This effect is a cornerstone of modern psycholinguistic models of word production, which assume that it arises in lexical response-selection. However, recent evidence from studies of dual-task performance suggests a locus in…

  4. Dual-Tasking Alleviated Sleep Deprivation Disruption in Visuomotor Tracking: An fMRI Study

    ERIC Educational Resources Information Center

    Gazes, Yunglin; Rakitin, Brian C.; Steffener, Jason; Habeck, Christian; Butterfield, Brady; Basner, Robert C.; Ghez, Claude; Stern, Yaakov

    2012-01-01

    Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a…

  5. Deep Thinking Increases Task-Set Shielding and Reduces Shifting Flexibility in Dual-Task Performance

    ERIC Educational Resources Information Center

    Fischer, Rico; Hommel, Bernhard

    2012-01-01

    Performing two tasks concurrently is difficult, which has been taken to imply the existence of a structural processing bottleneck. Here we sought to assess whether and to what degree one's multitasking abilities depend on the cognitive-control style one engages in. Participants were primed with creativity tasks that either called for divergent…

  6. The Role of Input and Output Modality Pairings in Dual-Task Performance: Evidence for Content-Dependent Central Interference

    ERIC Educational Resources Information Center

    Hazeltine, Eliot; Ruthruff, Eric; Remington, Roger W.

    2006-01-01

    Recent debate regarding dual-task performance has focused on whether costs result from limitations in central capacity, and whether central operations can be performed in parallel. While these questions are controversial, the dominant models of dual-task performance share the assumption that central operations are generic--that is, their…

  7. Age-Related Changes in Brain Activation Underlying Single- and Dual-Task Performance: Visuomanual Drawing and Mental Arithmetic

    ERIC Educational Resources Information Center

    Van Impe, A.; Coxon, J. P.; Goble, D. J.; Wenderoth, N.; Swinnen, S. P.

    2011-01-01

    Depending on task combination, dual-tasking can either be performed successfully or can lead to performance decrements in one or both tasks. Interference is believed to be caused by limitations in central processing, i.e. structural interference between the neural activation patterns associated with each task. In the present study, single- and…

  8. A Roving Dual-Presentation Simultaneity-Judgment Task to Estimate the Point of Subjective Simultaneity

    PubMed Central

    Yarrow, Kielan; Martin, Sian E.; Di Costa, Steven; Solomon, Joshua A.; Arnold, Derek H.

    2016-01-01

    The most popular tasks with which to investigate the perception of subjective synchrony are the temporal order judgment (TOJ) and the simultaneity judgment (SJ). Here, we discuss a complementary approach—a dual-presentation (2x) SJ task—and focus on appropriate analysis methods for a theoretically desirable “roving” design. Two stimulus pairs are presented on each trial and the observer must select the most synchronous. To demonstrate this approach, in Experiment 1 we tested the 2xSJ task alongside TOJ, SJ, and simple reaction-time (RT) tasks using audiovisual stimuli. We interpret responses from each task using detection-theoretic models, which assume variable arrival times for sensory signals at critical brain structures for timing perception. All tasks provide similar estimates of the point of subjective simultaneity (PSS) on average, and PSS estimates from some tasks were correlated on an individual basis. The 2xSJ task produced lower and more stable estimates of model-based (and thus comparable) sensory/decision noise than the TOJ. In Experiment 2 we obtained similar results using RT, TOJ, ternary, and 2xSJ tasks for all combinations of auditory, visual, and tactile stimuli. In Experiment 3 we investigated attentional prior entry, using both TOJs and 2xSJs. We found that estimates of prior-entry magnitude correlated across these tasks. Overall, our study establishes the practicality of the roving dual-presentation SJ task, but also illustrates the additional complexity of the procedure. We consider ways in which this task might complement more traditional procedures, particularly when it is important to estimate both PSS and sensory/decisional noise. PMID:27047434

  9. Dual-Task Processing When Task 1 Is Hard and Task 2 Is Easy: Reversed Central Processing Order?

    ERIC Educational Resources Information Center

    Leonhard, Tanja; Fernandez, Susana Ruiz; Ulrich, Rolf; Miller, Jeff

    2011-01-01

    Five psychological refractory period (PRP) experiments were conducted with an especially time-consuming first task (Experiments 1, 3, and 5: mental rotation; Experiments 2 and 4: memory scanning) and with equal emphasis on the first task and on the second (left-right tone judgment). The standard design with varying stimulus onset asynchronies…

  10. OTVE turbopump condition monitoring, task E.5

    NASA Technical Reports Server (NTRS)

    Coleman, Paul T.; Collins, J. J.

    1989-01-01

    Recent work has been carried out on development of isotope wear analysis and optical and eddy current technologies to provide bearing wear measurements and real time monitoring of shaft speed, shaft axial displacement and shaft orbit of the Orbit Transfer Vehicle hydrostatic bearing tester. Results show shaft axial displacement can be optically measured (at the same time as shaft orbital motion and speed) to within 0.3 mils by two fiberoptic deflectometers. Evaluation of eddy current probes showed that, in addition to measuring shaft orbital motion, they can be used to measure shaft speed without having to machine grooves on the shaft surface as is the usual practice for turbomachinery. The interim results of this condition monitoring effort are presented.

  11. Delays without Mistakes: Response Time and Error Distributions in Dual-Task

    PubMed Central

    Kamienkowski, Juan Esteban; Sigman, Mariano

    2008-01-01

    Background When two tasks are presented within a short interval, a delay in the execution of the second task has been systematically observed. Psychological theorizing has argued that while sensory and motor operations can proceed in parallel, the coordination between these modules establishes a processing bottleneck. This model predicts that the timing but not the characteristics (duration, precision, variability…) of each processing stage are affected by interference. Thus, a critical test to this hypothesis is to explore whether the qualitiy of the decision is unaffected by a concurrent task. Methodology/Principal Findings In number comparison–as in most decision comparison tasks with a scalar measure of the evidence–the extent to which two stimuli can be discriminated is determined by their ratio, referred as the Weber fraction. We investigated performance in a rapid succession of two non-symbolic comparison tasks (number comparison and tone discrimination) in which error rates in both tasks could be manipulated parametrically from chance to almost perfect. We observed that dual-task interference has a massive effect on RT but does not affect the error rates, or the distribution of errors as a function of the evidence. Conclusions/Significance Our results imply that while the decision process itself is delayed during multiple task execution, its workings are unaffected by task interference, providing strong evidence in favor of a sequential model of task execution. PMID:18787706

  12. The Effect of Writing Task and Task Conditions on Colombian EFL Learners' Language Use

    ERIC Educational Resources Information Center

    McDonough, Kim; Fuentes, César García

    2015-01-01

    This classroom study examines whether English L2 writers' language use differs depending on the writing task (operationalized as paragraph type), and task conditions (operationalized as individual or collaborative writing). The texts written by English L2 university students in Colombia (N = 26) in response to problem/solution and cause/effect…

  13. Effect of dual task type on gait and dynamic stability during stair negotiation at different inclinations.

    PubMed

    Madehkhaksar, Forough; Egges, Arjan

    2016-01-01

    Stair gait is a common daily activity with great potential risk for falls. Stairs have varying inclinations and people may perform other tasks concurrently with stair gait. This study investigated dual-task interference in the context of complex gait tasks, such as stair gait at different inclinations, a topic about which little is understood. We examined how secondary cognitive and manual tasks interfere with stair gait when a person concurrently performed tasks at different levels of complexity. Gait kinematic data and secondary task performance measures were obtained from fifteen healthy young males while ascending and descending a four-step staircase at three inclinations (17.7°, 29.4°, and 41.5°) as well as level walking. They performed a cognitive task, 'backward digit recall', a manual task, 'carrying a cup of water' and a combination of the two tasks. Gait performance and dynamic stability were assessed by gait speed and whole body center of mass (COM) range of motion in the medial-lateral direction, respectively. No significant effect of the gait task on the cognitive task performance was observed. In contrast, stair walking adversely affected the performance of the manual task compared to level walking. Overall, more difficult postural and secondary tasks resulted in a decrease in gait speed and variation in COM displacement within normal range. Results suggest that COM displacement and gait alterations might be adopted to enhance the stability, and optimize the secondary task performance while walking under challenging circumstances. Our findings are useful for balance and gait evaluation, and for future falls prediction.

  14. The effect of processing code, response modality and task difficulty on dual task performance and subjective workload in a manual system

    NASA Technical Reports Server (NTRS)

    Liu, Yili; Wickens, Christopher D.

    1987-01-01

    This paper reports on the first experiment of a series studying the effect of task structure and difficulty demand on time-sharing performance and workload in both automated and corresponding manual systems. The experimental task involves manual control time-shared with spatial and verbal decisions tasks of two levels of difficulty and two modes of response (voice or manual). The results provide strong evidence that tasks and processes competing for common processing resources are time shared less effecively and have higher workload than tasks competing for separate resources. Subjective measures and the structure of multiple resources are used in conjunction to predict dual task performance. The evidence comes from both single-task and from dual-task performance.

  15. Vestibular disorders and dual task performance: Impairment when walking a straight path

    PubMed Central

    Roberts, Jess C.; Cohen, Helen S.; Sangi-Haghpeykar, Haleh

    2013-01-01

    Locomotion is impaired in some people with vestibular disorders. Performance on cognitive tasks is also impaired in many people with vestibular disorders. The goal of this study was to determine if patients with vestibular disorders have decreased ability to complete a dual task performance involving a cognitive task, an additional motor task or both tasks, combined along a linear path. Subjects were normal, had benign paroxysmal positional vertigo, or had various vestibular disorders that caused unilateral weakness. They were asked to walk 7.62 m in a straight line with eyes open or closed, without extra tasks, and while nodding the head, naming things, and both nodding and naming. The patients walked significantly slower than controls, especially when performing the cognitive task. Patients had greater ataxia and began veering sooner than normals. The subjects’ veering increased significantly with the addition of cognitive tasks. The patient groups did not differ significantly from each other. The changes in velocity did not affect the veering. These data suggest that patients with vestibular disorders are impaired in their ability to complete a linear path when cognitive tasks are added. PMID:21558642

  16. Effect of Peripheral Communication Pace on Attention Allocation in a Dual-Task Situation

    NASA Astrophysics Data System (ADS)

    Gueddana, Sofiane; Roussel, Nicolas

    Peripheral displays allow continuous awareness of information while performing other activities. Monitoring such a display while performing a central task has a cognitive cost that depends on its perceptual salience and the distraction it causes, i.e. the amount of attention it attracts away from the user’s primary action. This paper considers the particular case of peripheral displays for interpersonal communication. It reports on an experiment that studied the effect of peripheral communication pace on subjects’ allocation of attention in a dual-task situation: a snapshot-based peripheral monitoring task where participants need to assess the presence of a remote person, and a central text-correcting task against the clock. Our results show that the addition of the peripheral task caused a drop in the success rate of the central task. As the pace of snapshots increased, success rate decreased on the peripheral task while on the central one, success rate remained the same but failures to reply in time occurred more frequently. These results suggest that the increase in pace of snapshots caused participants to change their strategy for the central task and allocate more attention to the peripheral one, not enough to maintain peripheral performance but also not to the point where it would affect central performance. Overall, our work suggests that peripheral communication pace subtly influences attention allocation in dual-task situations. We conclude by discussing how control over information pace could help users of communication systems to adjust their local distraction as well as the attention they draw from remote users.

  17. Influence of dual task and frailty on gait parameters of older community-dwelling individuals

    PubMed Central

    Guedes, Rita C.; Dias, Rosângela C.; Pereira, Leani S. M.; Silva, Sílvia L. A.; Lustosa, Lygia P.; Dias, João M. D.

    2014-01-01

    Background: Gait parameters such as gait speed (GS) are important indicators of functional capacity. Frailty Syndrome is closely related to GS and is also capable of predicting adverse outcomes. The cognitive demand of gait control is usually explored with dual-task (DT) methodology. Objective: To investigate the effect of DT and frailty on the spatio-temporal parameters of gait in older people and identify which variables relate to GS. Method: The presence of frailty was verified by Fried's Frailty Criteria. Cognitive function was evaluated with the Mini-Mental State Exam (MMSE) and gait parameters were analyzed through the GAITRite(r) system in the single-task and DT conditions. The Kolmogorov-Smirnov, ANOVA, and Pearson's Correlation tests were administered. Results: The participants were assigned to the groups frail (FG), pre-frail (PFG), and non-frail (NFG). During the DT, the three groups showed a decrease in GS, cadence, and stride length and an increase in stride time (p<0.001). The reduction in the GS of the FG during the DT showed a positive correlation with the MMSE scores (r=730; p=0.001) and with grip strength (r=681; p=0.001). Conclusions: Gait parameters are more affected by the DT, especially in the frail older subjects. The reduction in GS in the FG is associated with lower grip strength and lower scores in the MMSE. The GS was able to discriminate the older adults in the three levels of frailty, being an important measure of the functional capacity in this population. PMID:25372007

  18. Associations between prefrontal cortex activation and H-reflex modulation during dual task gait

    PubMed Central

    Meester, Daan; Al-Yahya, Emad; Dawes, Helen; Martin-Fagg, Penny; Piñon, Carmen

    2014-01-01

    Walking, although a largely automatic process, is controlled by the cortex and the spinal cord with corrective reflexes modulated through integration of neural signals from central and peripheral inputs at supraspinal level throughout the gait cycle. In this study we used an additional cognitive task to interfere with the automatic processing during walking in order to explore the neural mechanisms involved in healthy young adults. Participants were asked to walk on a treadmill at two speeds, both with and without additional cognitive load. We evaluated the impact of speed and cognitive load by analyzing activity of the prefrontal cortex (PFC) using functional Near-Infrared Spectroscopy (fNIRS) alongside spinal cord reflex activity measured by soleus H-reflex amplitude and gait changes obtained by using an inertial measuring unit. Repeated measures ANOVA revealed that fNIRS Oxy-Hb concentrations significantly increased in the PFC with dual task (walking while performing a cognitive task) compared to a single task (walking only; p < 0.05). PFC activity was unaffected by increases of walking speed. H-reflex amplitude and gait variables did not change in response to either dual task or increases in walking speed. When walking under additional cognitive load participants adapted by using greater activity in the PFC, but this adaptation did not detrimentally affect H-reflex amplitude or gait variables. Our findings suggest that in a healthy young population central mechanisms (PFC) are activated in response to cognitive loads but that H-reflex activity and gait performance can successfully be maintained. This study provides insights into the mechanisms behind healthy individuals safely performing dual task walking. PMID:24600375

  19. Differential facilitative effects of glucose administration on Stroop task conditions.

    PubMed

    Brandt, Karen R; Gibson, E Leigh; Rackie, James M

    2013-12-01

    Previous research has demonstrated that glucose administration improves memory performance. These glucose facilitation effects have been most reliably demonstrated in medial temporal lobe tasks with the greatest effects found for cognitively demanding tasks. The aim of the proposed research was to first explore whether such effects might be demonstrated in a frontal lobe task. A second aim was to investigate whether any beneficial effects of glucose may arise more prominently under tasks of increasing cognitive demand. To achieve these aims, the Stroop Task was administered to participants and effects of a drink of glucose (25 g) were compared with an aspartame-sweetened control drink on performance in young adults. Results demonstrated that glucose ingestion significantly reduced RTs in the congruent and incongruent conditions. No effect on error rates was observed. Of most importance was the finding that this glucose facilitative effect was significantly greatest in the most cognitively demanding task, that is, the incongruent condition. The present results support the contention that the glucose facilitation effect is most robust under conditions of enhanced task difficulty and demonstrate that such benefits extend to frontal lobe function.

  20. Contrasting single and multi-component working-memory systems in dual tasking.

    PubMed

    Nijboer, Menno; Borst, Jelmer; van Rijn, Hedderik; Taatgen, Niels

    2016-05-01

    Working memory can be a major source of interference in dual tasking. However, there is no consensus on whether this interference is the result of a single working memory bottleneck, or of interactions between different working memory components that together form a complete working-memory system. We report a behavioral and an fMRI dataset in which working memory requirements are manipulated during multitasking. We show that a computational cognitive model that assumes a distributed version of working memory accounts for both behavioral and neuroimaging data better than a model that takes a more centralized approach. The model's working memory consists of an attentional focus, declarative memory, and a subvocalized rehearsal mechanism. Thus, the data and model favor an account where working memory interference in dual tasking is the result of interactions between different resources that together form a working-memory system.

  1. Contrasting single and multi-component working-memory systems in dual tasking.

    PubMed

    Nijboer, Menno; Borst, Jelmer; van Rijn, Hedderik; Taatgen, Niels

    2016-05-01

    Working memory can be a major source of interference in dual tasking. However, there is no consensus on whether this interference is the result of a single working memory bottleneck, or of interactions between different working memory components that together form a complete working-memory system. We report a behavioral and an fMRI dataset in which working memory requirements are manipulated during multitasking. We show that a computational cognitive model that assumes a distributed version of working memory accounts for both behavioral and neuroimaging data better than a model that takes a more centralized approach. The model's working memory consists of an attentional focus, declarative memory, and a subvocalized rehearsal mechanism. Thus, the data and model favor an account where working memory interference in dual tasking is the result of interactions between different resources that together form a working-memory system. PMID:26859518

  2. Effect of aquatic dual-task training on balance and gait in stroke patients

    PubMed Central

    Kim, Kyoung; Lee, Dong-Kyu; Kim, Eun-Kyung

    2016-01-01

    [Purpose] The purpose of this study was to determine the effect of aquatic dual-task training on balance and gait in stroke patients. [Subjects and Methods] Twenty stroke patients were divided into the experimental (n=10) and control (n=10) groups. Both groups underwent neurodevelopmental treatment. The experimental group additionally underwent aquatic dual-task training for 30 minutes a day, 5 days a week, for 6 weeks. Balance was measured using the Berg balance scale, Five Times Sit-to Stand Test, and Functional Reach Test. Gait was measured using the 10-Meter Walk Test, Timed Up and Go Test, and Functional Gait Assessment. [Results] For intragroup comparison, the experimental group showed a significant change after the experiment in all balance and gait assessment tests. For intergroup comparison, the experimental group showed relatively more significant change after the experiment in all balance and gait assessment tests. [Conclusion] Our results showed that aquatic dual-task training has a positive effect on balance and gait in stroke patients. PMID:27512261

  3. Effect of aquatic dual-task training on balance and gait in stroke patients.

    PubMed

    Kim, Kyoung; Lee, Dong-Kyu; Kim, Eun-Kyung

    2016-07-01

    [Purpose] The purpose of this study was to determine the effect of aquatic dual-task training on balance and gait in stroke patients. [Subjects and Methods] Twenty stroke patients were divided into the experimental (n=10) and control (n=10) groups. Both groups underwent neurodevelopmental treatment. The experimental group additionally underwent aquatic dual-task training for 30 minutes a day, 5 days a week, for 6 weeks. Balance was measured using the Berg balance scale, Five Times Sit-to Stand Test, and Functional Reach Test. Gait was measured using the 10-Meter Walk Test, Timed Up and Go Test, and Functional Gait Assessment. [Results] For intragroup comparison, the experimental group showed a significant change after the experiment in all balance and gait assessment tests. For intergroup comparison, the experimental group showed relatively more significant change after the experiment in all balance and gait assessment tests. [Conclusion] Our results showed that aquatic dual-task training has a positive effect on balance and gait in stroke patients. PMID:27512261

  4. Protocol for a randomized comparison of integrated versus consecutive dual task practice in Parkinson’s disease: the DUALITY trial

    PubMed Central

    2014-01-01

    Background Multiple tasking is an integral part of daily mobility. Patients with Parkinson’s disease have dual tasking difficulties due to their combined motor and cognitive deficits. Two contrasting physiotherapy interventions have been proposed to alleviate dual tasking difficulties: either to discourage simultaneous execution of dual tasks (consecutive training); or to practice their concurrent use (integrated training). It is currently unclear which of these training methods should be adopted to achieve safe and consolidated dual task performance in daily life. Therefore, the proposed randomized controlled trial will compare the effects of integrated versus consecutive training of dual tasking (tested by combining walking with cognitive exercises). Methods and design Hundred and twenty patients with Parkinson’s disease will be recruited to participate in this multi-centered, single blind, randomized controlled trial. Patients in Hoehn & Yahr stage II-III, with or without freezing of gait, and who report dual task difficulties will be included. All patients will undergo a six-week control period without intervention after which they will be randomized to integrated or consecutive task practice. Training will consist of standardized walking and cognitive exercises delivered at home four times a week during six weeks. Treatment is guided by a physiotherapist twice a week and consists of two sessions of self-practice using an MP3 player. Blinded testers will assess patients before and after the control period, after the intervention period and after a 12-week follow-up period. The primary outcome measure is dual task gait velocity, i.e. walking combined with a novel untrained cognitive task to evaluate the consolidation of learning. Secondary outcomes include several single and dual task gait and cognitive measures, functional outcomes and a quality of life scale. Falling will be recorded as a possible adverse event using a weekly phone call for the entire

  5. Maintaining Gait Performance by Cortical Activation during Dual-Task Interference: A Functional Near-Infrared Spectroscopy Study.

    PubMed

    Lu, Chia-Feng; Liu, Yan-Ci; Yang, Yea-Ru; Wu, Yu-Te; Wang, Ray-Yau

    2015-01-01

    In daily life, mobility requires walking while performing a cognitive or upper-extremity motor task. Although previous studies have evaluated the effects of dual tasks on gait performance, few studies have evaluated cortical activation and its association with gait disturbance during dual tasks. In this study, we simultaneously assessed gait performance and cerebral oxygenation in the bilateral prefrontal cortices (PFC), premotor cortices (PMC), and supplemental motor areas (SMA), using functional near-infrared spectroscopy, in 17 young adults performing dual tasks. Each participant was evaluated while performing normal-pace walking (NW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT). Our results indicated that the left PFC exhibited the strongest and most sustained activation during WCT, and that NW and WMT were associated with minor increases in oxygenation levels during their initial phases. We observed increased activation in channels in the SMA and PMC during WCT and WMT. Gait data indicated that WCT and WMT both caused reductions in walking speed, but these reductions resulted from differing alterations in gait properties. WCT was associated with significant changes in cadence, stride time, and stride length, whereas WMT was associated with reductions in stride length only. During dual-task activities, increased activation of the PMC and SMA correlated with declines in gait performance, indicating a control mechanism for maintaining gait performance during dual tasks. Thus, the regulatory effects of cortical activation on gait behavior enable a second task to be performed while walking.

  6. Maintaining Gait Performance by Cortical Activation during Dual-Task Interference: A Functional Near-Infrared Spectroscopy Study

    PubMed Central

    Yang, Yea-Ru; Wu, Yu-Te; Wang, Ray-Yau

    2015-01-01

    In daily life, mobility requires walking while performing a cognitive or upper-extremity motor task. Although previous studies have evaluated the effects of dual tasks on gait performance, few studies have evaluated cortical activation and its association with gait disturbance during dual tasks. In this study, we simultaneously assessed gait performance and cerebral oxygenation in the bilateral prefrontal cortices (PFC), premotor cortices (PMC), and supplemental motor areas (SMA), using functional near-infrared spectroscopy, in 17 young adults performing dual tasks. Each participant was evaluated while performing normal-pace walking (NW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT). Our results indicated that the left PFC exhibited the strongest and most sustained activation during WCT, and that NW and WMT were associated with minor increases in oxygenation levels during their initial phases. We observed increased activation in channels in the SMA and PMC during WCT and WMT. Gait data indicated that WCT and WMT both caused reductions in walking speed, but these reductions resulted from differing alterations in gait properties. WCT was associated with significant changes in cadence, stride time, and stride length, whereas WMT was associated with reductions in stride length only. During dual-task activities, increased activation of the PMC and SMA correlated with declines in gait performance, indicating a control mechanism for maintaining gait performance during dual tasks. Thus, the regulatory effects of cortical activation on gait behavior enable a second task to be performed while walking. PMID:26079605

  7. Role of the Frontal Cortex in Standing Postural Sway Tasks While Dual-Tasking: A Functional Near-Infrared Spectroscopy Study Examining Working Memory Capacity.

    PubMed

    Fujita, Hiroyuki; Kasubuchi, Kenji; Wakata, Satoshi; Hiyamizu, Makoto; Morioka, Shu

    2016-01-01

    Posture control during a dual-task involves changing the distribution of attention resources between the cognitive and motor tasks and involves the frontal cortex working memory (WM). The present study aimed to better understand the impact of frontal lobe activity and WM capacity in postural control during a dual-task. High and low WM-span groups were compared using their reading span test scores. High and low WM capacity were compared based on cognitive and balance performance and hemoglobin oxygenation (oxyHb) levels during standing during single (S-S), standing during dual (S-D), one leg standing during single (O-S), and one leg standing during dual (O-D) tasks. For sway pass length, significant difference in only the O-D task was observed between both groups. oxyHb levels were markedly increased in the right dorsolateral prefrontal cortex and supplementary motor area in the high-span group during a dual-task. Therefore, WM capacity influenced the allocation of attentional resources and motor performance. PMID:27034947

  8. Dual-task information processing in schizotypal personality disorder: evidence of impaired processing capacity.

    PubMed

    Harvey, Philip D; Reichenberg, Abraham; Romero, Michelle; Granholm, Eric; Siever, Larry J

    2006-07-01

    Working memory theories heavily rely on the concept of processing resources and the their efficient deployment. Some recent work with schizophrenia-spectrum patients has suggested that many associated cognitive impairments may be reduced to deficits in working memory, possibly related to reductions in information-processing capacity resources. In this study, 38 patients with schizotypal personality disorder (SPD), 22 patients with other personality disorders, and 14 healthy comparison participants performed a dual-task processing assessment that was designed specifically for use in this type of study. Participants recalled lists of digits at their predetermined maximum digit span and performed box-checking tests, first alone and then in a dual-task format. Instructions included equal prioritization of both tasks. SPD patients had significantly shorter digit spans, and they also showed more deterioration on both tasks. Performance operating characteristics curves indicated that SPD patients' reduced performance was not due to abnormal resource allocation strategies leading to strategic failures. The authors discuss the implications of these processing capacity limitations for understanding both the signature of cognitive impairment within the schizophrenia spectrum and general abnormalities in working memory.

  9. [Electroencephalograpic Parameters of Healthy Persons with Different Successfulness of Dual-Task Performance (Postural Control and Calculation)].

    PubMed

    Zhavoronkova, L A; Kushnir, E M; Zharikova, A V; Kuptsova, S V; Shevtsova, T P; Koulikov, M A; Voronov, V G

    2015-01-01

    Complex electroencephalographic (EEG), stabilographic and psychological study was executed during the number dual tasks performance--postural control and calculation in 25 healthy volunteers (age 25 ± 0.7). Successful performances of dual tasks required a high usage of cognitive resources, such as memory and attention as well as good motor command and low level of anxiety. Two EEG-markers of successful dual tasks performance were revealed. An increase of EEG coherence for long diagonal pairs of leads between frontal and parieto-occipital areas was observed. Additionally a decrease of EEG coherence for short pairs of leads was revealed. The poor performance of dual tasks was accompanied by an increase of EEG coherence between local pairs of leads for different spectral bands. PMID:26860002

  10. Frontoparietal EEG alpha-phase synchrony reflects differential attentional demands during word recall and oculomotor dual-tasks.

    PubMed

    Kwon, Gusang; Kim, Min-Young; Lim, Sanghyun; Kwon, Hyukchan; Lee, Yong-Ho; Kim, Kiwoong; Lee, Eun-Ju; Suh, Minah

    2015-12-16

    To study the relationship between the varying degrees of cognitive load and long-range synchronization among neural networks, we utilized a dual-task paradigm combining concurrent word recall working memory tasks and oculomotor tasks that differentially activate the common frontoparietal (FP) network. We hypothesized that each dual-task combination would generate differential neuronal activation patterns among long-range connection during word retention period. Given that the FP alpha-phase synchronization is involved in attentional top-down processes, one would expect that the long-range synchronization pattern is affected by the degrees of dual-task demand. We measured a single-trial phase locking value in the alpha frequency (8-12 Hz) with electroencephalography in healthy participants. Single-trial phase locking value characterized the synchronization between two brain signals. Our results revealed that different amounts of FP alpha-phase synchronization were produced by different dual-task combinations, particularly during the early phase of the word retention period. These differences were dependent on the individual's working memory capacity and memory load. Our study shows that during dual-task, each oculomotor task, which is subserved by distinct neural network, generates different modulation patterns on long-range neuronal activation and FP alpha-phase synchronization seems to reflect these differential cognitive loads.

  11. Frontoparietal EEG alpha-phase synchrony reflects differential attentional demands during word recall and oculomotor dual-tasks.

    PubMed

    Kwon, Gusang; Kim, Min-Young; Lim, Sanghyun; Kwon, Hyukchan; Lee, Yong-Ho; Kim, Kiwoong; Lee, Eun-Ju; Suh, Minah

    2015-12-16

    To study the relationship between the varying degrees of cognitive load and long-range synchronization among neural networks, we utilized a dual-task paradigm combining concurrent word recall working memory tasks and oculomotor tasks that differentially activate the common frontoparietal (FP) network. We hypothesized that each dual-task combination would generate differential neuronal activation patterns among long-range connection during word retention period. Given that the FP alpha-phase synchronization is involved in attentional top-down processes, one would expect that the long-range synchronization pattern is affected by the degrees of dual-task demand. We measured a single-trial phase locking value in the alpha frequency (8-12 Hz) with electroencephalography in healthy participants. Single-trial phase locking value characterized the synchronization between two brain signals. Our results revealed that different amounts of FP alpha-phase synchronization were produced by different dual-task combinations, particularly during the early phase of the word retention period. These differences were dependent on the individual's working memory capacity and memory load. Our study shows that during dual-task, each oculomotor task, which is subserved by distinct neural network, generates different modulation patterns on long-range neuronal activation and FP alpha-phase synchronization seems to reflect these differential cognitive loads. PMID:26559729

  12. Automaticity in attractive face processing: brain potentials from a dual task.

    PubMed

    Rellecke, Julian; Bakirtas, Arda Melih; Sommer, Werner; Schacht, Annekathrin

    2011-10-01

    Attractive faces have a special status, possibly because of evolutionary reasons. We assessed the automaticity of facial attractiveness processing in a dual-task paradigm manipulating the availability of cognitive resources to face processing by a primary tone task presented at varying stimulus onset asynchrony (SOA). In event-related brain potentials, attractive relative to neutral faces induced an increased posterior negativity from 260 ms onwards indicating enhanced stimulus encoding at the cortical level. Interestingly, effects of attractive faces on event-related brain potentials were most pronounced at high temporal overlap with the primary task (short stimulus onset asynchrony). This indicates that a shortage of cognitive resources may enhance the processing of attractive faces, revealing hard-wired processing biases of the human information processing system for evolutionarily prepared stimuli.

  13. Dual Arm Work Package performance estimates and telerobot task network simulation

    SciTech Connect

    Draper, J.V.; Blair, L.M.

    1997-02-01

    This paper describes the methodology and results of a network simulation study of the Dual Arm Work Package (DAWP), to be employed for dismantling the Argonne National Laboratory CP-5 reactor. The development of the simulation model was based upon the results of a task analysis for the same system. This study was performed by the Oak Ridge National Laboratory (ORNL), in the Robotics and Process Systems Division. Funding was provided the US Department of Energy`s Office of Technology Development, Robotics Technology Development Program (RTDP). The RTDP is developing methods of computer simulation to estimate telerobotic system performance. Data were collected to provide point estimates to be used in a task network simulation model. Three skilled operators performed six repetitions of a pipe cutting task representative of typical teleoperation cutting operations.

  14. Free-throw shooting during dual-task performance: implications for attentional demand and performance.

    PubMed

    Price, Jayme; Gill, Diane L; Etnier, Jennifer; Kornatz, Kurt

    2009-12-01

    In this study, the dual-task paradigm was used to determine peak attentional demand during the free-throw process. Thirty participants completed 40 free-throw trials. The free throw was the primary task, but participants also verbally responded to a tone administered at one of four probe positions (PP). Repeated measures analysis of variance showed no significant difference in free-throw performance across PPs, indicating participants were able to keep the free throw as the primary task. Repeated measures analysis of response time (RT) showed significant differences, with RT at PP1 (preshot routine) and PP2 (first upward motion of the ball) significantly higher than baseline RT These results suggest that PP1 requires the greatest attentional demand, followed by PP2.

  15. New normative standards of conditional reasoning and the dual-source model

    PubMed Central

    Singmann, Henrik; Klauer, Karl Christoph; Over, David

    2014-01-01

    There has been a major shift in research on human reasoning toward Bayesian and probabilistic approaches, which has been called a new paradigm. The new paradigm sees most everyday and scientific reasoning as taking place in a context of uncertainty, and inference is from uncertain beliefs and not from arbitrary assumptions. In this manuscript we present an empirical test of normative standards in the new paradigm using a novel probabilized conditional reasoning task. Our results indicated that for everyday conditional with at least a weak causal connection between antecedent and consequent only the conditional probability of the consequent given antecedent contributes unique variance to predicting the probability of conditional, but not the probability of the conjunction, nor the probability of the material conditional. Regarding normative accounts of reasoning, we found significant evidence that participants' responses were confidence preserving (i.e., p-valid in the sense of Adams, 1998) for MP inferences, but not for MT inferences. Additionally, only for MP inferences and to a lesser degree for DA inferences did the rate of responses inside the coherence intervals defined by mental probability logic (Pfeifer and Kleiter, 2005, 2010) exceed chance levels. In contrast to the normative accounts, the dual-source model (Klauer et al., 2010) is a descriptive model. It posits that participants integrate their background knowledge (i.e., the type of information primary to the normative approaches) and their subjective probability that a conclusion is seen as warranted based on its logical form. Model fits showed that the dual-source model, which employed participants' responses to a deductive task with abstract contents to estimate the form-based component, provided as good an account of the data as a model that solely used data from the probabilized conditional reasoning task. PMID:24860516

  16. The role of control functions in mentalizing: dual-task studies of theory of mind and executive function.

    PubMed

    Bull, Rebecca; Phillips, Louise H; Conway, Claire A

    2008-05-01

    Conflicting evidence has arisen from correlational studies regarding the role of executive control functions in Theory of Mind. The current study used dual-task manipulations of executive functions (inhibition, updating and switching) to investigate the role of these control functions in mental state and non-mental state tasks. The 'Eyes' pictorial test of Theory of Mind showed specific dual-task costs when concurrently performed with an inhibitory secondary task. In contrast, interference effects on a verbal 'Stories' task were general, occurring on both mental state and non-mental state tasks, and across all types of executive function. These findings from healthy functioning adults should help to guide decisions about appropriate methods of assessing ToM in clinical populations, and interpreting deficits in performance in such tasks in the context of more general cognitive dysfunction.

  17. Auditory middle latency responses under different task conditions.

    PubMed

    Nishihira, Y; Araki, H; Ishihara, A; Funase, K; Nagao, T; Kinjo, S

    1994-01-01

    We examined the relationship between the Na and Pa components of human MLRs and the performance of different tasks. We also investigated whether MLRs are reliable indices of activity in the central motor-sensory system. The click stimuli we used consistently evoked the Na and Pa components. At CZ, the Na and Pa components significantly decreased for all tasks other than pegging with right hand while at FZ, these components were significantly decreased for all tasks. The Na and Pa latencies were slightly increased during task performances. These results indicate that the Na and Pa components of human MLRs decreased when various tasks were performed, while subjects were concentrating. A general principle of evoked potentials is that latencies decrease as amplitudes increase in excitation due to neural activation. Thus, it would appear that, under the conditions of this study, the pathways from the reticular formation and the thalamus to the primary auditory cortex were inhibited. Since the thalamus is considered to be the relay region for poly-sensory inputs, it is thought that the attenuation of the MLRs and SEPs occurs at the level of cerebral cortex, including the reticular formation, the thalamus, and the primary auditory cortex. Accordingly, since it is inferred that central factors are responsible for the attenuation of the MLRs, Na and Pa components observed during the performance of tasks carried out in the present experiment, it may be concluded that MLRs are reliable indices of activity in the central-motor system.

  18. Attention, gaze shifting, and dual-task interference from phonological encoding in spoken word planning.

    PubMed

    Roelofs, Ardi

    2008-12-01

    Controversy exists about whether dual-task interference from word planning reflects structural bottleneck or attentional control factors. Here, participants named pictures whose names could or could not be phonologically prepared, and they manually responded to arrows presented away from (Experiment 1), or superimposed onto, the pictures (Experiments 2 and 3); or they responded to tones (Experiment 4). Pictures and arrows/tones were presented at stimulus onset asynchronies of 0, 300, and 1,000 ms. Earlier research showed that vocal responding hampers auditory perception, which predicts earlier shifts of attention to the tones than to the arrows. Word planning yielded dual-task interference. Phonological preparation reduced the latencies of picture naming and gaze shifting. The preparation benefit was propagated into the latencies of the manual responses to the arrows but not to the tones. The malleability of the interference supports the attentional control account. This conclusion was corroborated by computer simulations showing that an extension of WEAVER++ (A. Roelofs, 2003) with assumptions about the attentional control of tasks quantitatively accounts for the latencies of vocal responding, gaze shifting, and manual responding. PMID:19045994

  19. The dual task-cost of standing balance affects quality of life in mildly disabled MS people.

    PubMed

    Castelli, Letizia; De Luca, Francesca; Marchetti, Maria Rita; Sellitto, Giovanni; Fanelli, Fulvia; Prosperini, Luca

    2016-05-01

    The aim of this study was to explore the correlations between the dual-task cost (DTC) of standing balance and quality of life (QoL) in mildly disabled patients with multiple sclerosis (MS). In this cross-sectional study, patients affected by MS with an expanded disability status scale (EDSS) score of 3.0 or less and without an overt balance impairment were tested by means of static posturography under eyes-opened (single-task condition) and while performing the Stroop word-color test (dual-task condition), to estimate the DTC of standing balance. The self-reported 54-item MS quality of life questionnaire (MSQoL-54) was also administered to obtain a MS-specific assessment of health-related QoL. Among the 120 screened patients, 75 (53 women, 22 men) were tested. Although there was no impact of the DTC of standing balance on the physical and mental composite scores of MSQoL-54, patients who had a greater DTC of standing balance scored worse on role limitations due to physical problems (p = 0.007) and social function (p < 0.001), irrespective of demographic and other clinical characteristics including walking performance and cognitive status. However, the EDSS step and fatigue also contributed to reduced scores in these two QoL domains (p-values < 0.01). In conclusion, the phenomenon of cognitive-motor interference, investigated as DTC of standing balance, may affect specific QoL domains even in mildly disabled patients with MS and in the absence of an overt balance dysfunction.

  20. A mixed Rasch model of dual-process conditional reasoning.

    PubMed

    Bonnefon, Jean-François; Eid, Michael; Vautier, Stéphane; Jmel, Saïd

    2008-05-01

    A fine-grained dual-process approach to conditional reasoning is advocated: Responses to conditional syllogisms are reached through the operation of either one of two systems, each of which can rely on two different mechanisms. System1 relies either on pragmatic implicatures or on the retrieval of information from semantic memory; System2 operates first through inhibition of System1, then (but not always) through activation of analytical processes. It follows that reasoners will fall into one of four groups of increasing reasoning ability, each group being uniquely characterized by (a) the modal pattern of individual answers to blocks of affirming the consequent (AC), denying the antecedent (DA), and modus tollens (MT) syllogisms featuring the same conditional; and (b) the average rate of determinate answers to AC, DA, and MT. This account receives indirect support from the extant literature and direct support from a mixed Rasch model of responses given to 18 syllogisms by 486 adult reasoners.

  1. Dual-task performance in older adults during discrete gait perturbation.

    PubMed

    Nnodim, Joseph O; Kim, Hogene; Ashton-Miller, James A

    2016-04-01

    The dual-task (motor and cognitive) performance of eight older adults (72.0 ± 6.4 years; 5 female; 3 male) was evaluated. Vocal choice reaction times (cognitive task) were measured at standstill as well as during unperturbed and perturbed gait (motor task). The perturbation was administered using customized shoes instrumented to lower a small (18.4 mm high) aluminum flap suddenly under the medial or lateral forefoot during a single swing phase of 12 of 30 gait trials. The ankle inverted or everted an average of 10 or 9 degrees, respectively, depending on the flap deployed. Medial and lateral perturbations were randomized between the left and right feet. The results show that vocal choice reaction time was significantly prolonged by gait, both perturbed (614.7 ± 80.2 ms) and unperturbed (529.9 ± 119.3 ms), compared to standstill (332.8 ± 76.5 ms; p = 0.0015). Further, the prolongation associated with gait perturbation was significant, compared to that with unperturbed gait (p = 0.016). The kinematics of the first post-perturbation (recovery) step, with or without concomitant vocal choice reaction task performance, was not significantly different from those of the average step during unperturbed gait. We conclude that in healthy older adults, the requirement to respond to a gait challenge resulted in deterioration in the performance of a concurrent cognitive task as indicated by significant prolongation of response time in the vocal choice reaction task. In contrast, performance of the motor task was not adversely affected.

  2. A dual-loop model of the human controller in single-axis tracking tasks

    NASA Technical Reports Server (NTRS)

    Hess, R. A.

    1977-01-01

    A dual loop model of the human controller in single axis compensatory tracking tasks is introduced. This model possesses an inner-loop closure which involves feeding back that portion of the controlled element output rate which is due to control activity. The sensory inputs to the human controller are assumed to be system error and control force. The former is assumed to be sensed via visual, aural, or tactile displays while the latter is assumed to be sensed in kinesthetic fashion. A nonlinear form of the model is briefly discussed. This model is then linearized and parameterized. A set of general adaptive characteristics for the parameterized model is hypothesized. These characteristics describe the manner in which the parameters in the linearized model will vary with such things as display quality. It is demonstrated that the parameterized model can produce controller describing functions which closely approximate those measured in laboratory tracking tasks for a wide variety of controlled elements.

  3. The Use of Cognitive Cues for Anticipatory Strategies in a Dynamic Postural Control Task - Validation of a Novel Approach to Dual-Task Testing

    PubMed Central

    Grarup, Bo; Bangshaab, Jette

    2016-01-01

    Introduction Dual-task testing is relevant in the assessment of postural control. A combination of a primary (motor) and a secondary (distracting cognitive) tasks is most often used. It remains a challenge however, to standardize and monitor the cognitive task. In this study a new dual-task testing approach with a facilitating, rather than distracting, cognitive component was evaluated. Methods Thirty-one community-dwelling elderly and fifteen young people were tested with respect to their ability to use anticipatory postural control strategies. The motor task consisted of twenty-five repetitive tasks in which the participants needed to exceed their limit of stability in order to touch one out of eight lights. The participants performed three tests. In two of the tests the color cues of the lights allowed the participants to utilize cognitive strategies to plan their next movement and improve their performance time. Results The young performed the baseline motor task test in an average of 29 seconds, while the average time for the elderly was 44 seconds. When comparing the performance time with a leading cue to the time with no cue, the young group improved their performance time significantly better than the elderly did: young: 17% (5), elderly: 5% (8); p<0.001. Similar differences were seen with a more complicated leading cue: young: 12% (5), elderly: 4% (9); p<0.01. The reliability of the test showed moderate to substantial agreement (ICC = 0.74), with a small learning effect between two sessions. Conclusion The dual-task test was sensitive enough to discriminate between elderly and young people. It revealed that the elderly did not utilize cognitive cues for their anticipatory postural control strategies as well as the young were able to. The test procedure was feasible and comprehensible for the participants, and it may be relevant to standardize a similar test for an alternative dual-task approach in the clinical setting. PMID:27487000

  4. Effects of spatial congruency on saccade and visual discrimination performance in a dual-task paradigm.

    PubMed

    Moehler, Tobias; Fiehler, Katja

    2014-12-01

    The present study investigated the coupling of selection-for-perception and selection-for-action during saccadic eye movement planning in three dual-task experiments. We focused on the effects of spatial congruency of saccade target (ST) location and discrimination target (DT) location and the time between ST-cue and Go-signal (SOA) on saccadic eye movement performance. In two experiments, participants performed a visual discrimination task at a cued location while programming a saccadic eye movement to a cued location. In the third experiment, the discrimination task was not cued and appeared at a random location. Spatial congruency of ST-location and DT-location resulted in enhanced perceptual performance irrespective of SOA. Perceptual performance in spatially incongruent trials was above chance, but only when the DT-location was cued. Saccade accuracy and precision were also affected by spatial congruency showing superior performance when the ST- and DT-location coincided. Saccade latency was only affected by spatial congruency when the DT-cue was predictive of the ST-location. Moreover, saccades consistently curved away from the incongruent DT-locations. Importantly, the effects of spatial congruency on saccade parameters only occurred when the DT-location was cued; therefore, results from experiments 1 and 2 are due to the endogenous allocation of attention to the DT-location and not caused by the salience of the probe. The SOA affected saccade latency showing decreasing latencies with increasing SOA. In conclusion, our results demonstrate that visuospatial attention can be voluntarily distributed upon spatially distinct perceptual and motor goals in dual-task situations, resulting in a decline of visual discrimination and saccade performance.

  5. The planetary water drama: Dual task of feeding humanity and curbing climate change

    NASA Astrophysics Data System (ADS)

    Rockström, J.; Falkenmark, M.; Lannerstad, M.; Karlberg, L.

    2012-08-01

    This paper analyses the potential conflict between resilience of the Earth system and global freshwater requirements for the dual task of carbon sequestration to reduce CO2 in the atmosphere, and food production to feed humanity by 2050. It makes an attempt to assess the order of magnitude of the increased consumptive water use involved and analyses the implications as seen from two parallel perspectives; the global perspective of human development within a “safe operating space” with regard to the definition of the Planetary Boundary for freshwater; and the social-ecological implications at the regional river basin scale in terms of sharpening water shortages and threats to aquatic ecosystems. The paper shows that the consumptive water use involved in the dual task would both transgress the proposed planetary boundary range for global consumptive freshwater use and would further exacerbate already severe river depletion, causing societal problems related to water shortage and water allocation. Thus, strategies to rely on sequestration of CO2 as a mitigation strategy must recognize the high freshwater costs involved, implying that the key climate mitigation strategy must be to reduce emissions. The paper finally highlights the need to analyze both water and carbon tradeoffs from anticipated large scale biofuel production climate change mitigation strategy, to reveal gains and impact of this in contrast to carbon sequestration strategies.

  6. Memorizing while walking: increase in dual-task costs from young adulthood to old age.

    PubMed

    Lindenberger, U; Marsiske, M; Baltes, P B

    2000-09-01

    The dual task of memorizing word lists while walking was predicted to become more difficult with age because balance and gait are in greater need of "attentional resources." Forty-seven young (ages 20-30 years), 45 middle-aged (40-50), and 48 old (60-70) adults were trained to criterion in a mnemonic technique and instructed to walk quickly and accurately on 2 narrow tracks of different path complexity. Then. participants encoded the word lists while sitting, standing, or walking on either track; likewise, speed and accuracy of walking performance were assessed with and without concurrent memory encoding. Dual-task costs increased with age in both domains; relative to young adults, the effect size of the overall increase was 0.98 standard deviation units for middle-aged and 1.47 standard deviation units for old adults. It is argued that sensory and motor aspects of behavior are increasingly in need of cognitive control with advancing age.

  7. Effects of regular exercise and dual tasking on spatial and temporal parameters of obstacle negotiation in elderly women.

    PubMed

    Guadagnin, E C; da Rocha, E S; Mota, C B; Carpes, F P

    2015-09-01

    This study investigated the effects of regular exercise and dual tasking on bilateral spatial and temporal parameters of obstacle negotiation in elderly women. Sedentary (n=12) and physically active (n=12) elderly women volunteered to participate in this study. Gait kinematics were recorded during obstacle crossing when performing a dual task and when not performing a dual task. Physically active participants crossed obstacles more safely, in terms of clearance or distance to or over the obstacle, both with and without dual tasking, and usually for both lead and trail legs. Performing the dual task increased toe distance, and decreased heel distance and gait speed in the active participants, and increased toe clearance and heel distance, and decreased gait speed in the sedentary participants. Differences between preferred and non-preferred leg were accentuated for toe clearance in the lead limb. These results suggest that specialized exercises may not be needed for improvement in obstacle avoidance skills in the elderly, and participation in multi-activities, including aerobic exercises, may be sufficient.

  8. Comparison of model and human observer performance for detection and discrimination tasks using dual-energy x-ray images

    SciTech Connect

    Richard, Samuel; Siewerdsen, Jeffrey H.

    2008-11-15

    Model observer performance, computed theoretically using cascaded systems analysis (CSA), was compared to the performance of human observers in detection and discrimination tasks. Dual-energy (DE) imaging provided a wide range of acquisition and decomposition parameters for which observer performance could be predicted and measured. This work combined previously derived observer models (e.g., Fisher-Hotelling and non-prewhitening) with CSA modeling of the DE image noise-equivalent quanta (NEQ) and imaging task (e.g., sphere detection, shape discrimination, and texture discrimination) to yield theoretical predictions of detectability index (d{sup '}) and area under the receiver operating characteristic (A{sub Z}). Theoretical predictions were compared to human observer performance assessed using 9-alternative forced-choice tests to yield measurement of A{sub Z} as a function of DE image acquisition parameters (viz., allocation of dose between the low- and high-energy images) and decomposition technique [viz., three DE image decomposition algorithms: standard log subtraction (SLS), simple-smoothing of the high-energy image (SSH), and anti-correlated noise reduction (ACNR)]. Results showed good agreement between theory and measurements over a broad range of imaging conditions. The incorporation of an eye filter and internal noise in the observer models demonstrated improved correspondence with human observer performance. Optimal acquisition and decomposition parameters were shown to depend on the imaging task; for example, ACNR and SSH yielded the greatest performance in the detection of soft-tissue and bony lesions, respectively. This study provides encouraging evidence that Fourier-based modeling of NEQ computed via CSA and imaging task provides a good approximation to human observer performance for simple imaging tasks, helping to bridge the gap between Fourier metrics of detector performance (e.g., NEQ) and human observer performance.

  9. Does extending the dual-task functional exercises workout improve postural balance in individuals with ID?

    PubMed

    Mikolajczyk, Edyta; Jankowicz-Szymanska, Agnieszka

    2015-03-01

    Maintaining postural balance, overcoming visual and motor coordination disorders and experiencing problems with low general fitness - typical of intellectually disabled individuals - adversely affect the performance quality of their activities of daily living (ADLs). Physical fitness and postural balance can be improved by taking part in special intervention programs. Our study was designed to test whether extending the dual-task intervention program (combining ADLs with balance exercises on unstable surfaces) from 12 to 24 weeks additionally improved postural balance in individuals with intellectual disability (ID). We also attempted to assess whether the effects of the above intervention program were still noticeable after 8 weeks of holidays, in which participants did not take any rehabilitation exercises. A total of 34 adolescents, aged 14-16 years (15.06±0.9), with moderate ID took part in our study. The experimental group (E) consisted of 17 individuals, who continued the intervention program originated 3 months earlier, and the control group (C) comprised the same number of participants. Postural balance was assessed on a stabilometric platform Alfa. Having extended the workout period by another 12 weeks, we noticed that the path length of the center of pressure (COP) covered by participants on tests with their eyes open and closed significantly shortened. After a lapse of 8 weeks from the completion of the program, the experimental group revealed a statistically significant decrease in the velocity along the medio-lateral (M/L) and anterior-posterior (A/P) axes. The remaining variables stayed at the same level and the control group did not demonstrate any statistically significant changes. Dual-task exercises, in which enhancing functional tasks of daily living is combined with a parallel stimulation of balance reactions, may improve static balance in persons with ID.

  10. Examining the time course of attention in a soccer kick using a dual task paradigm.

    PubMed

    Carr, Brendan M; Etnier, Jennifer L; Fisher, Kevin M

    2013-02-01

    A dual-task paradigm was implemented using a repeated measures design to determine the time course of attention demands during performance of a soccer penalty kick. Experienced soccer players (N=15) were asked to perform a 12-yard soccer-style penalty kick. As part of the dual task paradigm, participants were instructed to respond to an audible cue that was administered during one of three probe positions (PP) during the penalty kick. Probe position 1 (PP1) was operationalized as the participant's second to last step (taken with the non-kicking foot), probe position 2 (PP2) was the next to last step (taken with the kicking foot), and probe position 3 (PP3) was the last step (taken with the non-kicking, or "plant foot") just prior to the kicking foot making contact with the ball. Kicks were taken with both the dominant foot (DF) and the non-dominant foot (NDF). It was hypothesized that reaction time to the audible cue (RT) would be slowest at the beginning and end of the performance of the motor skill in both the DF and NDF situations and that RT would be slower when kicking with the NDF, but that the kicking foot would not affect the pattern of attentional demands. Results indicated that RT was slowest at PP1 for both the DF and the NDF and that RT was significantly slower at PP1 for the DF than for the NDF. This suggests that soccer players engage in more complex planning during the preparatory phases when executing a kick with their dominant foot. Future research should be designed to further our understanding of foot dominance with regard to kicking and to explore attentional demands of striking tasks.

  11. Sustained attention in traumatic brain injury (TBI) and healthy controls: enhanced sensitivity with dual-task load.

    PubMed

    Dockree, Paul M; Bellgrove, Mark A; O'Keeffe, Fiadhnait M; Moloney, Pauline; Aimola, Lina; Carton, Simone; Robertson, Ian H

    2006-01-01

    Poor sustained attention or alertness is a common consequence of traumatic brain injury (TBI) and has a considerable impact on the recovery and adjustment of TBI patients. Here, we describe the development of a sensitive laboratory task in healthy subjects (Experiment 1) and its enhanced sensitivity to sustained attention errors in TBI patients (Experiment 2). The task involves withholding a key press to an infrequent no-go target embedded within a predictable sequence of numbers (primary goal) and detecting grey-coloured targets within the sequence (secondary goal). In Experiment 1, we report that neurologically healthy subjects are more likely to experience a lapse of attention and neglect the primary task goal, despite ceiling performance on the secondary task. Further, attentional lapses on the task correlated with everyday attentional failures and variability of response time. In Experiment 2, the task discriminates between TBI patients and controls with a large effect size. The dual-task yields more errors in both groups than a simple task involving only the primary goal that is commonly used to detect sustained attention deficits in neurologically impaired groups. TBI patients' errors also correlated with everyday cognitive failures and variability of response time. This was not the case in the simple version of the task. We conclude that the dual-task demand associated with this task enhances its sensitivity as a measure of sustained attention in TBI patients and neurologically healthy controls that relates to everyday slips of attention.

  12. Reliability and validity of a dual-task test for skill proficiency in roundhouse kicks in elite taekwondo athletes.

    PubMed

    Chen, Chung-Yu; Dai, Jing; Chen, I-Fan; Chou, Kuei-Ming; Chang, Chen-Kang

    2015-01-01

    The dual-task methodology, conducting two tasks simultaneously, may provide better validity than the traditional single-task tests in the environment that is closely related to real sport competitions. The purpose of this study is to determine the reliability and validity of a dual-task test that aims to measure the reaction time and skill proficiency in roundhouse kicks in elite and sub-elite taekwondo athletes. The dual-task results were compared to those in the single-task movements with various levels of complexity. The single-task movements A, B, and C were composed of one, three, and five roundhouse kicks, respectively. The dual-task movement D was composed of movement C and a push of a button in response to a light stimulus as the secondary task. The subjects were 12 elite and 12 sub-elite male taekwondo athletes. The test included four movements with five repeats of each movement in a randomized order. Each subject conducted the same test on two consecutive days. The intraclass correlation coefficient (ICC) showed moderate-to-high correlation in the premotor time (ICC =0.439-0.634 in elite and ICC =0.681-0.824 in sub-elite), motor time (ICC =0.861-0.956 in elite and ICC =0.721-0.931 in sub-elite), and reaction time (ICC =0.692 in elite and ICC =0.676 in sub-elite) in the secondary task in both groups. The elite athletes had significantly faster premotor time than their sub-elite counterparts in all the four movements (all P<0.05). The largest difference lies in the reaction time in the secondary task, in which the elite group (0.248±0.026 seconds) was 33.0% faster than the sub-elite group (0.370±0.081 seconds) (P<0.001). This study shows that the test developed in this study has reasonable reliability and validity in both single- and dual-task methods. In addition, the dual-task method may be a more appropriate way to assess the reaction time and skill proficiency in taekwondo athletes.

  13. Effect of a dual task on postural control in dyslexic children.

    PubMed

    Legrand, Agathe; Bui-Quoc, Emmanuel; Doré-Mazars, Karine; Lemoine, Christelle; Gérard, Christophe-Loïc; Bucci, Maria Pia

    2012-01-01

    Several studies have examined postural control in dyslexic children; however, their results were inconclusive. This study investigated the effect of a dual task on postural stability in dyslexic children. Eighteen dyslexic children (mean age 10.3±1.2 years) were compared with eighteen non-dyslexic children of similar age. Postural stability was recorded with a platform (TechnoConcept®) while the child, in separate sessions, made reflex horizontal and vertical saccades of 10° of amplitude, and read a text silently. We measured the surface and the mean speed of the center of pressure (CoP). Reading performance was assessed by counting the number of words read during postural measures. Both groups of children were more stable while performing saccades than while reading a text. Furthermore, dyslexic children were significantly more unstable than non-dyslexic children, especially during the reading task. Finally, the number of words read by dyslexic children was significantly lower than that of non-dyslexic children and, in contrast to the non-dyslexic children. In line with the U-shaped non-linear interaction model, we suggest that the attention consumed by the reading task could be responsible for the loss of postural control in both groups of children. The postural instability observed in dyslexic children supports the hypothesis that such children have a lack of integration of multiple sensorimotor inputs.

  14. Predicting the language proficiency of Chinese student pilots within American airspace: Single-task versus dual-task English-language assessment

    NASA Astrophysics Data System (ADS)

    Noble, Clifford Elliott, II

    2002-09-01

    The problem. The purpose of this study was to investigate the ability of three single-task instruments---(a) the Test of English as a Foreign Language, (b) the Aviation Test of Spoken English, and (c) the Single Manual-Tracking Test---and three dual-task instruments---(a) the Concurrent Manual-Tracking and Communication Test, (b) the Certified Flight Instructor's Test, and (c) the Simulation-Based English Test---to predict the language performance of 10 Chinese student pilots speaking English as a second language when operating single-engine and multiengine aircraft within American airspace. Method. This research implemented a correlational design to investigate the ability of the six described instruments to predict the mean score of the criterion evaluation, which was the Examiner's Test. This test assessed the oral communication skill of student pilots on the flight portion of the terminal checkride in the Piper Cadet, Piper Seminole, and Beechcraft King Air airplanes. Results. Data from the Single Manual-Tracking Test, as well as the Concurrent Manual-Tracking and Communication Test, were discarded due to performance ceiling effects. Hypothesis 1, which stated that the average correlation between the mean scores of the dual-task evaluations and that of the Examiner's Test would predict the mean score of the criterion evaluation with a greater degree of accuracy than that of single-task evaluations, was not supported. Hypothesis 2, which stated that the correlation between the mean scores of the participants on the Simulation-Based English Test and the Examiner's Test would predict the mean score of the criterion evaluation with a greater degree of accuracy than that of all single- and dual-task evaluations, was also not supported. The findings suggest that single- and dual-task assessments administered after initial flight training are equivalent predictors of language performance when piloting single-engine and multiengine aircraft.

  15. Electrocortical Sources Related to Whole-Body Surface Translations during a Single- and Dual-Task Paradigm

    PubMed Central

    Bogost, Mark D.; Burgos, Pablo I.; Little, C. Elaine; Woollacott, Marjorie H.; Dalton, Brian H.

    2016-01-01

    Appropriate reactive motor responses are essential in maintaining upright balance. However, little is known regarding the potential location of cortical sources that are related to the onset of a perturbation during single- and dual-task paradigms. The purpose of this study was to estimate the location of cortical sources in response to a whole-body surface translation and whether diverted attention decreases the N1 event-related potential (ERP) amplitude related to a postural perturbation. This study utilized high-resolution electroencephalography in conjunction with measure projection analysis from ERPs time-locked to backwards surface translation onsets to determine which cortical sources were related to whole-body postural perturbations. Subjects (n = 15) either reacted to whole-body surface translations with (dual task) or without (single task) performing a visual working memory task. For the single task, four domains were identified that were mainly localized within the frontal and parietal lobes and included sources from the prefrontal, premotor, primary and supplementary motor, somatosensory and anterior cingulate cortex. Five domains were estimated for the dual task and also included sources within the frontal and parietal lobes, but the sources also shifted to other locations that included areas within the temporal and occipital lobes. Additionally, mean absolute N1 ERP amplitudes representing the activity from similar locations in both tasks were greater for the single than dual task. The present localization results highlight the importance of frontal, parietal and anterior cingulate cortical areas in reactive postural control and suggest a re-allocation or shift of cortical sources related to reactive balance control in the presence of a secondary task. Thus, this study provides novel insight into the underlying neurophysiology and contribution of cortical sources in relation to the neural control of reactive balance. PMID:27803658

  16. Conditioning of Model Identification Task in Immune Inspired Optimizer SILO

    NASA Astrophysics Data System (ADS)

    Wojdan, K.; Swirski, K.; Warchol, M.; Maciorowski, M.

    2009-10-01

    Methods which provide good conditioning of model identification task in immune inspired, steady-state controller SILO (Stochastic Immune Layer Optimizer) are presented in this paper. These methods are implemented in a model based optimization algorithm. The first method uses a safe model to assure that gains of the process's model can be estimated. The second method is responsible for elimination of potential linear dependences between columns of observation matrix. Moreover new results from one of SILO implementation in polish power plant are presented. They confirm high efficiency of the presented solution in solving technical problems.

  17. Tracking reading: dual task costs of oral reading for young versus older adults.

    PubMed

    Kemper, Susan; Bontempo, Daniel; Schmalzried, RaLynn; McKedy, Whitney; Tagliaferri, Bruno; Kieweg, Doug

    2014-02-01

    A digital pursuit rotor was used to monitor oral reading costs by time-locking tracking performance to the auditory wave form produced as young and older adults were reading out short paragraphs. Multilevel modeling was used to determine how paragraph-level predictors of length, grammatical complexity, and readability and person-level predictors such as speaker age or working memory capacity predicted reading and tracking performance. In addition, sentence-by-sentence variation in tracking performance was examined during the production of individual sentences and during the pauses before upcoming sentences. The results suggest that dual tasking has a greater impact on older adults' reading comprehension and tracking performance. At the level of individual sentences, young and older adults adopt different strategies to deal with grammatically complex and propositionally dense sentences.

  18. Serial or overlapping processing in multitasking as individual preference: Effects of stimulus preview on task switching and concurrent dual-task performance.

    PubMed

    Reissland, Jessika; Manzey, Dietrich

    2016-07-01

    Understanding the mechanisms and performance consequences of multitasking has long been in focus of scientific interest, but has been investigated by three research lines more or less isolated from each other. Studies in the fields of the psychological refractory period, task switching, and interruptions have scored with a high experimental control, but usually do not give participants many degrees of freedom to self-organize the processing of two concurrent tasks. Individual strategies as well as their impact on efficiency have mainly been neglected. Self-organized multitasking has been investigated in the field of human factors, but primarily with respect to overall performance without detailed investigation of how the tasks are processed. The current work attempts to link aspects of these research lines. All of them, explicitly or implicitly, provide hints about an individually preferred type of task organization, either more cautious trying to work strictly serially on only one task at a time or more daring with a focus on task interleaving and, if possible, also partially overlapping (parallel) processing. In two experiments we investigated different strategies of task organization and their impact on efficiency using a new measure of overall multitasking efficiency. Experiment 1 was based on a classical task switching paradigm with two classification tasks, but provided one group of participants with a stimulus preview of the task to switch to next, enabling at least partial overlapping processing. Indeed, this preview led to a reduction of switch costs and to an increase of dual-task efficiency, but only for a subgroup of participants. They obviously exploited the possibility of overlapping processing, while the others worked mainly serially. While task-sequence was externally guided in the first experiment, Experiment 2 extended the approach by giving the participants full freedom of task organization in concurrent performance of the same tasks. Fine

  19. Serial or overlapping processing in multitasking as individual preference: Effects of stimulus preview on task switching and concurrent dual-task performance.

    PubMed

    Reissland, Jessika; Manzey, Dietrich

    2016-07-01

    Understanding the mechanisms and performance consequences of multitasking has long been in focus of scientific interest, but has been investigated by three research lines more or less isolated from each other. Studies in the fields of the psychological refractory period, task switching, and interruptions have scored with a high experimental control, but usually do not give participants many degrees of freedom to self-organize the processing of two concurrent tasks. Individual strategies as well as their impact on efficiency have mainly been neglected. Self-organized multitasking has been investigated in the field of human factors, but primarily with respect to overall performance without detailed investigation of how the tasks are processed. The current work attempts to link aspects of these research lines. All of them, explicitly or implicitly, provide hints about an individually preferred type of task organization, either more cautious trying to work strictly serially on only one task at a time or more daring with a focus on task interleaving and, if possible, also partially overlapping (parallel) processing. In two experiments we investigated different strategies of task organization and their impact on efficiency using a new measure of overall multitasking efficiency. Experiment 1 was based on a classical task switching paradigm with two classification tasks, but provided one group of participants with a stimulus preview of the task to switch to next, enabling at least partial overlapping processing. Indeed, this preview led to a reduction of switch costs and to an increase of dual-task efficiency, but only for a subgroup of participants. They obviously exploited the possibility of overlapping processing, while the others worked mainly serially. While task-sequence was externally guided in the first experiment, Experiment 2 extended the approach by giving the participants full freedom of task organization in concurrent performance of the same tasks. Fine

  20. Dual-Task Performance with Ideomotor-Compatible Tasks: Is the Central Processing Bottleneck Intact, Bypassed, or Shifted in Locus?

    ERIC Educational Resources Information Center

    Lien, Mei-Ching; McCann, Robert S.; Ruthruff, Eric; Proctor, Robert W.

    2005-01-01

    The present study examined whether the central bottleneck, assumed to be primarily responsible for the psychological refractory period (PRP) effect, is intact, bypassed, or shifted in locus with ideomotor (IM)-compatible tasks. In 4 experiments, factorial combinations of IM- and non-IM-compatible tasks were used for Task 1 and Task 2. All…

  1. What Phonological Facilitation Tells about Semantic Interference: A Dual-Task Study

    PubMed Central

    Ayora, Pauline; Peressotti, Francesca; Alario, F.-Xavier; Mulatti, Claudio; Pluchino, Patrick; Job, Remo; Dell'Acqua, Roberto

    2011-01-01

    Despite increasing interest in the topic, the extent to which linguistic processing demands attentional resources remains poorly understood. We report an empirical re-examination of claims about lexical processing made on the basis of the picture–word interference task when merged in a dual-task psychological refractory period (PRP) paradigm. Two experiments were conducted in which participants were presented with a tone followed, at varying stimulus onset asynchronies (SOAs), by a picture–word stimulus. In Experiment 1, the phonological relatedness between pictures and words was manipulated. Begin- and end-related words decreased picture naming latencies relative to unrelated words. This effect was additive with SOA effects. In Experiment 2, both the semantic and the phonological relatedness between pictures and words were manipulated. Replicating Experiment 1, effects arising from the phonological manipulation were additive with SOA effects on picture naming latencies. In contrast, effects arising from the semantic manipulation were under additive with SOA effects on picture naming latencies, that is, semantic interference decreased as SOA was decreased. Such contrastive pattern suggests that semantic and phonological effects on picture naming latencies are characterized by distinguishable sources, the former prior to the PRP bottleneck and the latter at the PRP bottleneck or after. The present findings are discussed in relation to current models of language production. PMID:21716584

  2. Spatial and temporal EEG dynamics of dual-task driving performance

    PubMed Central

    2011-01-01

    Background Driver distraction is a significant cause of traffic accidents. The aim of this study is to investigate Electroencephalography (EEG) dynamics in relation to distraction during driving. To study human cognition under a specific driving task, simulated real driving using virtual reality (VR)-based simulation and designed dual-task events are built, which include unexpected car deviations and mathematics questions. Methods We designed five cases with different stimulus onset asynchrony (SOA) to investigate the distraction effects between the deviations and equations. The EEG channel signals are first converted into separated brain sources by independent component analysis (ICA). Then, event-related spectral perturbation (ERSP) changes of the EEG power spectrum are used to evaluate brain dynamics in time-frequency domains. Results Power increases in the theta and beta bands are observed in relation with distraction effects in the frontal cortex. In the motor area, alpha and beta power suppressions are also observed. All of the above results are consistently observed across 15 subjects. Additionally, further analysis demonstrates that response time and multiple cortical EEG power both changed significantly with different SOA. Conclusions This study suggests that theta power increases in the frontal area is related to driver distraction and represents the strength of distraction in real-life situations. PMID:21332977

  3. Dual-task performance with ideomotor-compatible tasks: is the central processing bottleneck intact, bypassed, or shifted in locus?

    NASA Technical Reports Server (NTRS)

    Lien, Mei-Ching; McCann, Robert S.; Ruthruff, Eric; Proctor, Robert W.

    2005-01-01

    The present study examined whether the central bottleneck, assumed to be primarily responsible for the psychological refractory period (PRP) effect, is intact, bypassed, or shifted in locus with ideomotor (IM)-compatible tasks. In 4 experiments, factorial combinations of IM- and non-IM-compatible tasks were used for Task 1 and Task 2. All experiments showed substantial PRP effects, with a strong dependency between Task 1 and Task 2 response times. These findings, along with model-based simulations, indicate that the processing bottleneck was not bypassed, even with two IM-compatible tasks. Nevertheless, systematic changes in the PRP and correspondence effects across experiments suggest that IM compatibility shifted the locus of the bottleneck. The findings favor an engage-bottleneck-later hypothesis, whereby parallelism between tasks occurs deeper into the processing stream for IM- than for non-IM-compatible tasks, without the bottleneck being actually eliminated.

  4. Reduced mental capacity and behavior of a rider of a bicycle simulator under alcohol stress or under dual task load

    NASA Technical Reports Server (NTRS)

    Soede, M.

    1977-01-01

    Experiments were carried out on a bicycle simulator with alcohol administration and a binary choice task in separate sessions, intending to reduce the subject's mental capacity. Before and after such sessions a visual evoked response measurement was done. The subject's performance was analyzed with describing function techniques. The results indicate that the alcohol affects the course-following task as well as the balancing task. The binary choice task is more specifically influencing the course-following task. The dual task shows a more pronounced effect on the recovery of the evoked response. The alcohol is delaying the recovery curve of the evoked response. A tentative explanation can be given which agrees with the performance data.

  5. Single and dual task tests of gait speed are equivalent in the prediction of falls in older people: a systematic review and meta-analysis.

    PubMed

    Menant, Jasmine C; Schoene, Daniel; Sarofim, Mina; Lord, Stephen R

    2014-07-01

    Although simple assessments of gait speed have been shown to predict falls as well as hospitalisation, functional decline and mortality in older people, dual task gait speed paradigms have been increasingly evaluated with respect to fall prediction. Some studies have found that dual task walking paradigms can predict falls in older people. A systematic review and meta-analysis was conducted to determine whether dual task walking paradigms involving a secondary cognitive task have greater ability to predict falls than single walking tasks. The meta-analytic findings indicate single and dual task tests of gait speed are equivalent in the prediction of falls in older people and sub-group analyses revealed similar findings for studies that included only cognitively impaired participants, slow walkers or used secondary mental-tracking or verbal fluency tasks.

  6. Gait in amyotrophic lateral sclerosis: Is gait pattern differently affected in spinal and bulbar onset of the disease during dual task walking?

    PubMed

    Radovanović, Sasa; Milićev, Milena; Perić, Stojan; Basta, Ivana; Kostić, Vladimir; Stević, Zorica

    2014-12-01

    Amyotrophic lateral sclerosis (ALS) is characterized by weakness, fatigue, loss of balance and coordination. The purpose of the study was to examine gait in ALS patients. Gait was compared in ALS with spinal and bulbar onset, while performing dual mental and motor tasks. Dual-task walking was performed by 27 ALS patients, 13 with spinal- and 14 with bulbar-onset disease. Twenty-nine healthy subjects were used as a control group. The subjects performed a basic, simple walking task, dual-motor task, dual-mental task, and combined motor and mental tasks. Results showed that dual-task paradigm has an effect on gait in ALS patients. Gait was differently affected in spinal and bulbar onset of ALS by some of the given tasks. Mental tasks had a larger effect than motor tasks in all gait parameters. In conclusion, both ALS forms have impaired gait in dual tasks. Simple walk in patients with spinal onset shows higher variability of certain gait parameters compared to bulbar-onset patients and controls. Differences in gait could also indicate postural instability and possible falls in complex walking situations.

  7. Simulated Firefighting Task Performance and Physiology Under Very Hot Conditions

    PubMed Central

    Larsen, Brianna; Snow, Rod; Williams-Bell, Michael; Aisbett, Brad

    2015-01-01

    Purpose: To assess the impact of very hot (45°C) conditions on the performance of, and physiological responses to, a simulated firefighting manual-handling task compared to the same work in a temperate environment (18°C). Methods: Ten male volunteer firefighters performed a 3-h protocol in both 18°C (CON) and 45°C (VH). Participants intermittently performed 12 × 1-min bouts of raking, 6 × 8-min bouts of low-intensity stepping, and 6 × 20-min rest periods. The area cleared during the raking task determined work performance. Core temperature, skin temperature, and heart rate were measured continuously. Participants also periodically rated their perceived exertion (RPE) and thermal sensation. Firefighters consumed water ad libitum. Urine specific gravity (USG) and changes in body mass determined hydration status. Results: Firefighters raked 19% less debris during the VH condition. Core and skin temperature were 0.99 ± 0.20 and 5.45 ± 0.53°C higher, respectively, during the VH trial, and heart rate was 14–36 beats.min−1 higher in the VH trial. Firefighters consumed 2950 ± 1034 mL of water in the VH condition, compared to 1290 ± 525 in the CON trial. Sweat losses were higher in the VH (1886 ± 474 mL) compared to the CON trial (462 ± 392 mL), though both groups were hydrated upon protocol completion (USG < 1.020). Participants' average RPE was higher in the VH (15.6 ± 0.9) compared to the CON trial (12.6 ± 0.9). Similarly, the firefighers' thermal sensation scores were significantly higher in the VH (6.4 ± 0.5) compared to the CON trial (4.4 ± 0.4). Conclusions: Despite the decreased work output and aggressive fluid replacement observed in the VH trial, firefighters' experienced increases in thermal stress, and exertion. Fire agencies should prioritize the health and safety of fire personnel in very hot temperatures, and consider the impact of reduced productivity on fire suppression efforts. PMID:26617527

  8. Comparable Cerebral Oxygenation Patterns in Younger and Older Adults during Dual-Task Walking with Increasing Load

    PubMed Central

    Fraser, Sarah A.; Dupuy, Olivier; Pouliot, Philippe; Lesage, Frédéric; Bherer, Louis

    2016-01-01

    The neuroimaging literature on dual-task gait clearly demonstrates increased prefrontal cortex (PFC) involvement when performing a cognitive task while walking. However, findings from direct comparisons of the cerebral oxygenation patterns of younger (YA) and older (OA) adults during dual-task walking are mixed and it is unclear how YA and OA respond to increasing cognitive load (difficulty) while walking. This functional near infra-red (fNIRS) study examined cerebral oxygenation of YA and OA during self-paced dual-task treadmill walking at two different levels of cognitive load (auditory n-back). Changes in accuracy (%) as well as oxygenated (HbO) and deoxygenated (HbR) hemoglobin were examined. For the HbO and HbR measures, eight regions of interest (ROIs) were assessed: the anterior and posterior dorsolateral and ventrolateral PFC (aDLPFC, pDLPFC, aVLPFC, pVLPFC) in each hemisphere. Nineteen YA (M = 21.83 years) and 14 OA (M = 66.85 years) walked at a self-selected pace while performing auditory 1-back and 2-back tasks. Walking alone (single motor: SM) and performing the cognitive tasks alone (single cognitive: SC) were compared to dual-task walking (DT = SM + SC). In the behavioural data, participants were more accurate in the lowest level of load (1-back) compared to the highest (2-back; p < 0.001). YA were more accurate than OA overall (p = 0.009), and particularly in the 2-back task (p = 0.048). In the fNIRS data, both younger and older adults had task effects (SM < DT) in specific ROIs for ΔHbO (three YA, one OA) and ΔHbR (seven YA, eight OA). After controlling for walk speed differences, direct comparisons between YA and OA did not reveal significant age differences, but did reveal a difficulty effect in HbO in the left aDLPFC (p = 0.028) and significant task effects (SM < DT) in HbR for six of the eight ROIs. Findings suggest that YA and OA respond similarly to manipulations of cognitive load when walking on a treadmill at a self-selected pace. PMID

  9. The Effect of a Six-Month Dancing Program on Motor-Cognitive Dual-Task Performance in Older Adults.

    PubMed

    Hamacher, Dennis; Hamacher, Daniel; Rehfeld, Kathrin; Hökelmann, Anita; Schega, Lutz

    2015-10-01

    Dancing is a complex sensorimotor activity involving physical and mental elements which have positive effects on cognitive functions and motor control. The present randomized controlled trial aims to analyze the effects of a dancing program on the performance on a motor-cognitive dual task. Data of 35 older adults, who were assigned to a dancing group or a health-related exercise group, are presented in the study. In pretest and posttest, we assessed cognitive performance and variability of minimum foot clearance, stride time, and stride length while walking. Regarding the cognitive performance and the stride-to-stride variability of minimum foot clearance, interaction effects have been found, indicating that dancing lowers gait variability to a higher extent than conventional health-related exercise. The data show that dancing improves minimum foot clearance variability and cognitive performance in a dual-task situation. Multi-task exercises (like dancing) might be a powerful tool to improve motor-cognitive dual-task performance.

  10. Mental subtraction and multiplication recruit both phonological and visuospatial resources: evidence from a symmetric dual-task design.

    PubMed

    Cavdaroglu, Seda; Knops, A

    2016-07-01

    Previous studies pointed out a selective interaction between different working memory subsystems (i.e., phonological and visuospatial) and arithmetic operations (i.e., multiplication and subtraction). This was interpreted to support the idea that multiplication and subtraction predominantly rely on a phonologically or spatially organized number code, respectively. Here, we investigated this idea in two groups (multiplication and subtraction group) using a dual-task paradigm. Going beyond previous studies, we carefully controlled and balanced the difficulty of both working memory and calculation tasks within and across participants. This allowed us to test the reciprocal impact of calculations on working memory. We observed no selective interaction between different working memory subsystems and arithmetic operations. Instead, both types of arithmetic operations were impaired by both types of concurrent working memory tasks. Likewise, both types of working memory tasks were impaired by both types of concurrent arithmetic. Our findings suggest that multiplication and subtraction depend on both phonological and visuospatial codes and highlight the importance of balancing task demands within and between participants in the context of dual-task studies. PMID:25952478

  11. Effects of cues in a binary categorization task on dual-task performance, mental workload, and effort.

    PubMed

    Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

    2016-09-01

    Binary cues help operators perform binary categorization tasks, such as monitoring for system failures. They may also allow them to attend to other tasks they concurrently perform. If the time saved by using cues is allocated to other concurrent tasks, users' overall effort may remain unchanged. In 2 experiments, participants performed a simulated quality control task, together with a tracking task. In half the experimental blocks cues were available, and participants could use them in their decisions about the quality of products (intact or faulty). In Experiment 1, the difficulty of tracking was constant, while in Experiment 2, tracking difficulty differed in the 2 halves of the experiment. In both experiments, participants reported on the NASA Task Load Index that cues improved their performance and reduced their frustration. Consequently, their overall score on mental workload (MWL) was lower with cues. They also reported, however, that cues did not reduce their effort. We conclude that cues and other forms of automation may support task performance and reduce overall MWL, but this will not necessarily mean that users will work less hard. Thus, effort and overall MWL should be evaluated separately, if one wants to obtain a full picture of the effects of automation. (PsycINFO Database Record PMID:27505049

  12. Effects of cues in a binary categorization task on dual-task performance, mental workload, and effort.

    PubMed

    Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

    2016-09-01

    Binary cues help operators perform binary categorization tasks, such as monitoring for system failures. They may also allow them to attend to other tasks they concurrently perform. If the time saved by using cues is allocated to other concurrent tasks, users' overall effort may remain unchanged. In 2 experiments, participants performed a simulated quality control task, together with a tracking task. In half the experimental blocks cues were available, and participants could use them in their decisions about the quality of products (intact or faulty). In Experiment 1, the difficulty of tracking was constant, while in Experiment 2, tracking difficulty differed in the 2 halves of the experiment. In both experiments, participants reported on the NASA Task Load Index that cues improved their performance and reduced their frustration. Consequently, their overall score on mental workload (MWL) was lower with cues. They also reported, however, that cues did not reduce their effort. We conclude that cues and other forms of automation may support task performance and reduce overall MWL, but this will not necessarily mean that users will work less hard. Thus, effort and overall MWL should be evaluated separately, if one wants to obtain a full picture of the effects of automation. (PsycINFO Database Record

  13. Brain activation during dual-task processing is associated with cardiorespiratory fitness and performance in older adults

    PubMed Central

    Wong, Chelsea N.; Chaddock-Heyman, Laura; Voss, Michelle W.; Burzynska, Agnieszka Z.; Basak, Chandramallika; Erickson, Kirk I.; Prakash, Ruchika S.; Szabo-Reed, Amanda N.; Phillips, Siobhan M.; Wojcicki, Thomas; Mailey, Emily L.; McAuley, Edward; Kramer, Arthur F.

    2015-01-01

    Higher cardiorespiratory fitness is associated with better cognitive performance and enhanced brain activation. Yet, the extent to which cardiorespiratory fitness-related brain activation is associated with better cognitive performance is not well understood. In this cross-sectional study, we examined whether the association between cardiorespiratory fitness and executive function was mediated by greater prefrontal cortex activation in healthy older adults. Brain activation was measured during dual-task performance with functional magnetic resonance imaging in a sample of 128 healthy older adults (59–80 years). Higher cardiorespiratory fitness was associated with greater activation during dual-task processing in several brain areas including the anterior cingulate and supplementary motor cortex (ACC/SMA), thalamus and basal ganglia, right motor/somatosensory cortex and middle frontal gyrus, and left somatosensory cortex, controlling for age, sex, education, and gray matter volume. Of these regions, greater ACC/SMA activation mediated the association between cardiorespiratory fitness and dual-task performance. We provide novel evidence that cardiorespiratory fitness may support cognitive performance by facilitating brain activation in a core region critical for executive function. PMID:26321949

  14. Optimization of dual-energy imaging systems using generalized NEQ and imaging task

    SciTech Connect

    Richard, S.; Siewerdsen, J. H.

    2007-01-15

    Dual-energy (DE) imaging is a promising advanced application of flat-panel detectors (FPDs) with a potential host of applications ranging from thoracic and cardiac imaging to interventional procedures. The performance of FPD-based DE imaging systems is investigated in this work by incorporating the noise-power spectrum associated with overlying anatomical structures (''anatomical noise'' modeled according to a 1/f characteristic) into descriptions of noise-equivalent quanta (NEQ) to yield the generalized NEQ (GNEQ). Signal and noise propagation in the DE imaging chain is modeled by cascaded systems analysis. A Fourier-based description of the imaging task is integrated with the GNEQ to yield a detectability index used as an objective function for optimizing DE image reconstruction, allocation of dose between low- and high-energy images, and selection of low- and high-kVp. Optimal reconstruction and acquisition parameters were found to depend on dose; for example, optimal kVp varied from [60/150] kVp at typical radiographic dose levels ({approx}0.5 mGy entrance surface dose, ESD) but increased to [90/150] kVp at high dose (ESD{approx}5.0 mGy). At very low dose (ESD{approx}0.05 mGy), detectability index indicates an optimal low-energy technique of 60 kVp but was largely insensitive to the choice of high-kVp in the range 120-150 kVp. Similarly, optimal dose allocation, defined as the ratio of low-energy ESD and the total ESD, varied from 0.2 to 0.4 over the range ESD=(0.05-5.0) mGy. Furthermore, two applications of the theoretical framework were explored: (i) the increase in detectability for DE imaging compared to conventional radiography; and (ii) the performance of single-shot vs double-shot DE imaging, wherein the latter is found to have a DQE approximately twice that of the former. Experimental and theoretical analysis of GNEQ and task-based detectability index provides a fundamental understanding of the factors governing DE imaging performance and offers a

  15. Dual conception of risk in the Iowa Gambling Task: effects of sleep deprivation and test-retest gap

    PubMed Central

    Singh, Varsha

    2013-01-01

    Risk in the Iowa Gambling Task (IGT) is often understood in terms of intertemporal choices, i.e., preference for immediate outcomes in favor of delayed outcomes is considered risky decision making. According to behavioral economics, healthy decision makers are expected to refrain from choosing the short-sighted immediate gain because, over time (10 trials of the IGT), the immediate gains result in a long term loss (net loss). Instead decision makers are expected to maximize their gains by choosing options that, over time (10 trials), result in delayed or long term gains (net gain). However, task choices are sometimes made on the basis of the frequency of reward and punishment such that frequent rewards/infrequent punishments are favored over infrequent rewards/frequent punishments. The presence of these two attributes (intertemporality and frequency of reward) in IGT decision making may correspond to the emotion-cognition dichotomy and reflect a dual conception of risk. Decision making on the basis of the two attributes was tested under two conditions: delay in retest and sleep deprivation. An interaction between sleep deprivation and time delay was expected to attenuate the difference between the two attributes. Participants were 40 male university students. Analysis of the effects of IGT attribute type (intertemporal vs. frequency of reinforcement), sleep deprivation (sleep deprivation vs. no sleep deprivation), and test-retest gap (short vs. long delay) showed a significant within-subjects effect of IGT attribute type thus confirming the difference between the two attributes. Sleep deprivation had no effect on the attributes, but test-retest gap and the three-way interaction between attribute type, test-retest gap, and sleep deprivation were significantly different. Post-hoc tests revealed that sleep deprivation and short test-retest gap attenuated the difference between the two attributes. Furthermore, the results showed an expected trend of increase in

  16. Dual conception of risk in the Iowa Gambling Task: effects of sleep deprivation and test-retest gap.

    PubMed

    Singh, Varsha

    2013-01-01

    Risk in the Iowa Gambling Task (IGT) is often understood in terms of intertemporal choices, i.e., preference for immediate outcomes in favor of delayed outcomes is considered risky decision making. According to behavioral economics, healthy decision makers are expected to refrain from choosing the short-sighted immediate gain because, over time (10 trials of the IGT), the immediate gains result in a long term loss (net loss). Instead decision makers are expected to maximize their gains by choosing options that, over time (10 trials), result in delayed or long term gains (net gain). However, task choices are sometimes made on the basis of the frequency of reward and punishment such that frequent rewards/infrequent punishments are favored over infrequent rewards/frequent punishments. The presence of these two attributes (intertemporality and frequency of reward) in IGT decision making may correspond to the emotion-cognition dichotomy and reflect a dual conception of risk. Decision making on the basis of the two attributes was tested under two conditions: delay in retest and sleep deprivation. An interaction between sleep deprivation and time delay was expected to attenuate the difference between the two attributes. Participants were 40 male university students. Analysis of the effects of IGT attribute type (intertemporal vs. frequency of reinforcement), sleep deprivation (sleep deprivation vs. no sleep deprivation), and test-retest gap (short vs. long delay) showed a significant within-subjects effect of IGT attribute type thus confirming the difference between the two attributes. Sleep deprivation had no effect on the attributes, but test-retest gap and the three-way interaction between attribute type, test-retest gap, and sleep deprivation were significantly different. Post-hoc tests revealed that sleep deprivation and short test-retest gap attenuated the difference between the two attributes. Furthermore, the results showed an expected trend of increase in

  17. Dual conception of risk in the Iowa Gambling Task: effects of sleep deprivation and test-retest gap.

    PubMed

    Singh, Varsha

    2013-01-01

    Risk in the Iowa Gambling Task (IGT) is often understood in terms of intertemporal choices, i.e., preference for immediate outcomes in favor of delayed outcomes is considered risky decision making. According to behavioral economics, healthy decision makers are expected to refrain from choosing the short-sighted immediate gain because, over time (10 trials of the IGT), the immediate gains result in a long term loss (net loss). Instead decision makers are expected to maximize their gains by choosing options that, over time (10 trials), result in delayed or long term gains (net gain). However, task choices are sometimes made on the basis of the frequency of reward and punishment such that frequent rewards/infrequent punishments are favored over infrequent rewards/frequent punishments. The presence of these two attributes (intertemporality and frequency of reward) in IGT decision making may correspond to the emotion-cognition dichotomy and reflect a dual conception of risk. Decision making on the basis of the two attributes was tested under two conditions: delay in retest and sleep deprivation. An interaction between sleep deprivation and time delay was expected to attenuate the difference between the two attributes. Participants were 40 male university students. Analysis of the effects of IGT attribute type (intertemporal vs. frequency of reinforcement), sleep deprivation (sleep deprivation vs. no sleep deprivation), and test-retest gap (short vs. long delay) showed a significant within-subjects effect of IGT attribute type thus confirming the difference between the two attributes. Sleep deprivation had no effect on the attributes, but test-retest gap and the three-way interaction between attribute type, test-retest gap, and sleep deprivation were significantly different. Post-hoc tests revealed that sleep deprivation and short test-retest gap attenuated the difference between the two attributes. Furthermore, the results showed an expected trend of increase in

  18. Dual-task and electrophysiological markers of executive cognitive processing in older adult gait and fall-risk.

    PubMed

    Walshe, Elizabeth A; Patterson, Matthew R; Commins, Seán; Roche, Richard A P

    2015-01-01

    The role of cognition is becoming increasingly central to our understanding of the complexity of walking gait. In particular, higher-level executive functions are suggested to play a key role in gait and fall-risk, but the specific underlying neurocognitive processes remain unclear. Here, we report two experiments which investigated the cognitive and neural processes underlying older adult gait and falls. Experiment 1 employed a dual-task (DT) paradigm in young and older adults, to assess the relative effects of higher-level executive function tasks (n-Back, Serial Subtraction and visuo-spatial Clock task) in comparison to non-executive distracter tasks (motor response task and alphabet recitation) on gait. All DTs elicited changes in gait for both young and older adults, relative to baseline walking. Significantly greater DT costs were observed for the executive tasks in the older adult group. Experiment 2 compared normal walking gait, seated cognitive performances and concurrent event-related brain potentials (ERPs) in healthy young and older adults, to older adult fallers. No significant differences in cognitive performances were found between fallers and non-fallers. However, an initial late-positivity, considered a potential early P3a, was evident on the Stroop task for older non-fallers, which was notably absent in older fallers. We argue that executive control functions play a prominent role in walking and gait, but the use of neurocognitive processes as a predictor of fall-risk needs further investigation.

  19. Context-Sensitive Adjustment of Cognitive Control in Dual-Task Performance

    ERIC Educational Resources Information Center

    Fischer, Rico; Gottschalk, Caroline; Dreisbach, Gesine

    2014-01-01

    Performing 2 highly similar tasks at the same time requires an adaptive regulation of cognitive control to shield prioritized primary task processing from between-task (cross-talk) interference caused by secondary task processing. In the present study, the authors investigated how implicitly and explicitly delivered information promotes the…

  20. The role of domain-general frontal systems in language comprehension: evidence from dual-task interference and semantic ambiguity.

    PubMed

    Rodd, Jennifer M; Johnsrude, Ingrid S; Davis, Matthew H

    2010-12-01

    Neuroimaging studies have shown that the left inferior frontal gyrus (LIFG) plays a critical role in semantic and syntactic aspects of speech comprehension. It appears to be recruited when listeners are required to select the appropriate meaning or syntactic role for words within a sentence. However, this region is also recruited during tasks not involving sentence materials, suggesting that the systems involved in processing ambiguous words within sentences are also recruited for more domain-general tasks that involve the selection of task-relevant information. We use a novel dual-task methodology to assess whether the cognitive system(s) that are engaged in selecting word meanings are also involved in non-sentential tasks. In Experiment 1, listeners were slower to decide whether a visually presented letter is in upper or lower case when the sentence that they are simultaneously listening to contains words with multiple meanings (homophones), compared to closely matched sentences without homophones. Experiment 2 indicates that this interference effect is not tied to the occurrence of the homophone itself, but rather occurs when listeners must reinterpret a sentence that was initially misparsed. These results suggest some overlap between the cognitive system involved in semantic disambiguation and the domain-general process of response selection required for the case-judgement task. This cognitive overlap may reflect neural overlap in the networks supporting these processes, and is consistent with the proposal that domain-general selection processes in inferior frontal regions are critical for language comprehension.

  1. Is Semantic Processing During Sentence Reading Autonomous or Controlled? Evidence from the N400 Component in a Dual Task Paradigm

    PubMed Central

    Hohlfeld, Annette; Martín-Loeches, Manuel; Sommer, Werner

    2015-01-01

    The present study contributes to the discussion on the automaticity of semantic processing. Whereas most previous research investigated semantic processing at word level, the present study addressed semantic processing during sentence reading. A dual task paradigm was combined with the recording of event-related brain potentials. Previous research at word level processing reported different patterns of interference with the N400 by additional tasks: attenuation of amplitude or delay of latency. In the present study, we presented Spanish sentences that were semantically correct or contained a semantic violation in a critical word. At different intervals preceding the critical word a tone was presented that required a high-priority choice response. At short intervals/high temporal overlap between the tasks mean amplitude of the N400 was reduced relative to long intervals/low temporal overlap, but there were no shifts of peak latency. We propose that processing at sentence level exerts a protective effect against the additional task. This is in accord with the attentional sensitization model (Kiefer & Martens, 2010), which suggests that semantic processing is an automatic process that can be enhanced by the currently activated task set. The present experimental sentences also induced a P600, which is taken as an index of integrative processing. Additional task effects are comparable to those in the N400 time window and are briefly discussed. PMID:26203312

  2. Assessment of upper body accelerations in young adults with intellectual disabilities while walking, running, and dual-task running.

    PubMed

    Iosa, Marco; Morelli, Daniela; Nisi, Enrica; Sorbara, Carlo; Negrini, Stefano; Gentili, Paola; Paolucci, Stefano; Fusco, Augusto

    2014-04-01

    There is an increasing interest about upper body accelerations during locomotion and how they are altered by physical impairments. Recent studies have demonstrated that cognitive impairments affect gait stability in the elderly (i.e., their capacity for smoothing upper body accelerations during walking) but little attention has been paid to young adults with intellectual disabilities. The purpose of this study was to examine upright stability in young adults with intellectual disabilities during walking, running, and dual-task running (playing soccer). To this aim a wearable trunk-mounted device that permits on-field assessment was used to quantify trunk acceleration of 18 male teenagers with intellectual disabilities (IDG) and 7 mental-age-matched healthy children (HCG) who participated in the same soccer program. We did not find any significant difference during walking in terms of speed, whereas speed differences were found during running (p=.001). Upper body accelerations were altered in a pathology-specific manner during the dual task: the performance of subjects with autistic disorders was compromised while running and controlling the ball with the feet. Differences in upright locomotor patterns between IDG and HCG emerged during more demanding motor tasks in terms of a loss in the capacity of smoothing accelerations at the trunk level.

  3. Conditional Reasoning in Context: A Dual-Source Model of Probabilistic Inference

    ERIC Educational Resources Information Center

    Klauer, Karl Christoph; Beller, Sieghard; Hutter, Mandy

    2010-01-01

    A dual-source model of probabilistic conditional inference is proposed. According to the model, inferences are based on 2 sources of evidence: logical form and prior knowledge. Logical form is a decontextualized source of evidence, whereas prior knowledge is activated by the contents of the conditional rule. In Experiments 1 to 3, manipulations of…

  4. Spatial release of cognitive load measured in a dual-task paradigm in normal-hearing and hearing-impaired listeners.

    PubMed

    Xia, Jing; Nooraei, Nazanin; Kalluri, Sridhar; Edwards, Brent

    2015-04-01

    This study investigated whether spatial separation between talkers helps reduce cognitive processing load, and how hearing impairment interacts with the cognitive load of individuals listening in multi-talker environments. A dual-task paradigm was used in which performance on a secondary task (visual tracking) served as a measure of the cognitive load imposed by a speech recognition task. Visual tracking performance was measured under four conditions in which the target and the interferers were distinguished by (1) gender and spatial location, (2) gender only, (3) spatial location only, and (4) neither gender nor spatial location. Results showed that when gender cues were available, a 15° spatial separation between talkers reduced the cognitive load of listening even though it did not provide further improvement in speech recognition (Experiment I). Compared to normal-hearing listeners, large individual variability in spatial release of cognitive load was observed among hearing-impaired listeners. Cognitive load was lower when talkers were spatially separated by 60° than when talkers were of different genders, even though speech recognition was comparable in these two conditions (Experiment II). These results suggest that a measure of cognitive load might provide valuable insight into the benefit of spatial cues in multi-talker environments. PMID:25920841

  5. Do Children with Autism Use Inner Speech and Visuospatial Resources for the Service of Executive Control? Evidence From Suppression in Dual Tasks

    ERIC Educational Resources Information Center

    Holland, Lucy; Low, Jason

    2010-01-01

    Three experiments used dual-task suppression methodology to study the use of inner speech and visuospatial resources for mediating central executive performance by children with autism (CWA) and group-matched typically developing (TD) controls. Expt 1 revealed that CWA did not recruit inner speech to facilitate arithmetic task-switching…

  6. [Effects of motor activity on cognitive performance of patients with traumatic brain injury during dual tasking].

    PubMed

    Useros-Olmo, A I; Perianez, J A; Miangolarra-Page, J C

    2015-09-01

    Introduccion. El empleo de paradigmas de tarea dual ha mostrado interacciones conductuales entre ciertas tareas motoras, como el equilibrio o la marcha, y tareas cognitivas al ser realizadas simultaneamente. Pese a la potencial relevancia de estos hallazgos en la explicacion de ciertos sintomas neurologicos (por ejemplo, caidas) o en el diseño de nuevas intervenciones, son escasos los datos sobre tales efectos en traumatismos craneoencefalicos (TCE). Objetivo. Evaluar la presencia de interacciones cognitivomotoras durante la realizacion de tareas duales en TCE. Sujetos y metodos. Veinte pacientes con TCE y 19 controles sanos realizaron diferentes tareas cognitivas de atencion y memoria operativa (tareas de tiempo de reaccion simple, tiempo de reaccion compleja, 1-back numerica y 1-back espacial) en tarea dual, es decir, al tiempo que una tarea motora (bipedestacion y marcha), y en tarea simple (sin tarea motora). Se registraron los tiempos de reaccion en respuesta a las tareas cognitivas. Resultados. Los pacientes mostraron peor rendimiento que los controles en todas las tareas (p < 0,05). Mientras que ninguno de los grupos mostro cambios en los tiempos de reaccion medidos en las tareas atencionales durante la ejecucion dual en comparacion con la ejecucion simple, los pacientes con TCE si mostraron mejoria en las tareas de memoria operativa (F(2, 74) = 2,9; p < 0,05) durante la tarea dual de marcha (p < 0,02). Conclusiones. Se discuten las posibles causas de interacciones cognitivomotoras positivas durante la ejecucion simultanea de tareas de marcha y memoria operativa en pacientes con TCE, y el potencial valor terapeutico de los paradigmas duales en la rehabilitacion de estos pacientes.

  7. Time-Resolved Decoding of Two Processing Chains during Dual-Task Interference.

    PubMed

    Marti, Sébastien; King, Jean-Rémi; Dehaene, Stanislas

    2015-12-16

    The human brain exhibits fundamental limitations in multitasking. When subjects engage in a primary task, their ability to respond to a second stimulus is degraded. Two competing models of multitasking have been proposed: either cognitive resources are shared between tasks, or they are allocated to each task serially. Using a novel combination of magneto-encephalography and multivariate pattern analyses, we obtained a precise spatio-temporal decomposition of the brain processes at work during multitasking. We discovered that each task relies on a sequence of brain processes. These sequences can operate in parallel for several hundred milliseconds but beyond ∼ 500 ms, they repel each other: processes evoked by the first task are shortened, while processes of the second task are either lengthened or postponed. These results contradict the resource-sharing model and further demonstrate that the serial model is incomplete. We therefore propose a new theoretical framework for the computational architecture underlying multitasking. PMID:26627309

  8. Dual functions of perirhinal cortex in fear conditioning.

    PubMed

    Kent, Brianne A; Brown, Thomas H

    2012-10-01

    The present review examines the role of perirhinal cortex (PRC) in Pavlovian fear conditioning. The focus is on rats, partly because so much is known, behaviorally and neurobiologically, about fear conditioning in these animals. In addition, the neuroanatomy and neurophysiology of rat PRC have been described in considerable detail at the cellular and systems levels. The evidence suggests that PRC can serve at least two types of mnemonic functions in Pavlovian fear conditioning. The first function, termed "stimulus unitization," refers to the ability to treat two or more separate items or stimulus elements as a single entity. Supporting evidence for this perceptual function comes from studies of context conditioning as well as delay conditioning to discontinuous auditory cues. In a delay paradigm, the conditional stimulus (CS) and unconditional stimulus (US) overlap temporally and co-terminate. The second PRC function entails a type of "transient memory." Supporting evidence comes from studies of trace cue conditioning, where there is a temporal gap or trace interval between the CS offset and the US onset. For learning to occur, there must be a transient CS representation during the trace interval. We advance a novel neurophysiological mechanism for this transient representation. These two hypothesized functions of PRC are consistent with inferences based on non-aversive forms of learning.

  9. Cognitive and Neural Determinants of Response Strategy in the Dual-Solution Plus-Maze Task

    ERIC Educational Resources Information Center

    De Leonibus, Elvira; Costantini, Vivian J. A.; Massaro, Antonio; Mandolesi, Georgia; Vanni, Valentina; Luvisetto, Siro; Pavone, Flaminia; Oliverio, Alberto; Mele, Andrea

    2011-01-01

    Response strategy in the dual-solution plus maze is regarded as a form of stimulus-response learning. In this study, by using an outcome devaluation procedure, we show that it can be based on both action-outcome and stimulus-response habit learning, depending on the amount of training that the animals receive. Furthermore, we show that…

  10. Assessing Relational Complexity in Hierarchical Reasoning: A Dual-Task Approach.

    ERIC Educational Resources Information Center

    Foley, Elizabeth J.; Berch, Daniel B.

    This study used the "double easy-to-hard" paradigm to examine the hypothesis that the class inclusion (CI) task should be equivalent in relational complexity to the transitive inference (TI) problem. Participating in the study were 64 girls and 50 boys, with a mean age of 8 years, 6 months. Stimuli for easy versions of the tasks were displayed…

  11. Evaluation of 2 cognitive abilities tests in a dual-task environment

    NASA Technical Reports Server (NTRS)

    Vidulich, M. A.; Tsang, P. S.

    1986-01-01

    Most real world operators are required to perform multiple tasks simultaneously. In some cases, such as flying a high performance aircraft or trouble shooting a failing nuclear power plant, the operator's ability to time share or process in parallel" can be driven to extremes. This has created interest in selection tests of cognitive abilities. Two tests that have been suggested are the Dichotic Listening Task and the Cognitive Failures Questionnaire. Correlations between these test results and time sharing performance were obtained and the validity of these tests were examined. The primary task was a tracking task with dynamically varying bandwidth. This was performed either alone or concurrently with either another tracking task or a spatial transformation task. The results were: (1) An unexpected negative correlation was detected between the two tests; (2) The lack of correlation between either test and task performance made the predictive utility of the tests scores appear questionable; (3) Pilots made more errors on the Dichotic Listening Task than college students.

  12. 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…

  13. Role of Dual Task Design When Measuring Cognitive Load during Multimedia Learning

    ERIC Educational Resources Information Center

    Schoor, Cornelia; Bannert, Maria; Brunken, Roland

    2012-01-01

    This study assessed the role different kinds of secondary tasks play for researching the modality effect of cognitive load theory. Ninety-six university students worked with a computer-based training program for approximately 13 min and had to fulfill an additional secondary task. In a 2 x 2 factorial design, modality of information presentation…

  14. A dual-task investigation of automaticity in visual word processing

    NASA Technical Reports Server (NTRS)

    McCann, R. S.; Remington, R. W.; Van Selst, M.

    2000-01-01

    An analysis of activation models of visual word processing suggests that frequency-sensitive forms of lexical processing should proceed normally while unattended. This hypothesis was tested by having participants perform a speeded pitch discrimination task followed by lexical decisions or word naming. As the stimulus onset asynchrony between the tasks was reduced, lexical-decision and naming latencies increased dramatically. Word-frequency effects were additive with the increase, indicating that frequency-sensitive processing was subject to postponement while attention was devoted to the other task. Either (a) the same neural hardware shares responsibility for lexical processing and central stages of choice reaction time task processing and cannot perform both computations simultaneously, or (b) lexical processing is blocked in order to optimize performance on the pitch discrimination task. Either way, word processing is not as automatic as activation models suggest.

  15. The Association between Different Levels of Alcohol Use and Gait under Single and Dual Task in Community-Dwelling Older Persons Aged 65 to 70 Years

    PubMed Central

    Büla, Christophe; Santos-Eggimann, Brigitte

    2016-01-01

    Objectives. This study aimed to describe the cross-sectional and longitudinal association between alcohol intake and gait parameters in older persons. Methods. Community-dwelling persons aged 65–70 years (N = 807). Information on health, functional status, and alcohol use was self-reported at baseline and at 3-year follow-up, whereas gait speed and stride-to-stride variability were measured while walking only (single task) and under dual tasking (counting backwards). Results. Compared to light-to-moderate drinking, heavy drinking was associated with slower gait speed in single task (adj. coeff.: −.040, 95% CI: −.0.78 to −.002, p = .035). No significant association was observed between heavy drinking and gait speed variability. Nondrinkers walked significantly slower than light-to-moderate drinkers in dual task and had significantly higher gait speed variability in both single and dual task, but these associations disappeared after adjustment for comorbidity. At follow-up, 35.2% and 34.1% of the participants walked significantly slower in single and dual task, respectively. This proportion varied a little across drinking categories. Conclusion. At baseline, heavy alcohol consumption was significantly associated with slower gait speed in single task. Selective survival of the fittest heavy drinkers probably explains why this association faded in longitudinal analyses. The trend of poorer gait performance in nondrinkers disappeared after adjustment for comorbidity, suggesting confounding by a worse health status. PMID:27516773

  16. The Association between Different Levels of Alcohol Use and Gait under Single and Dual Task in Community-Dwelling Older Persons Aged 65 to 70 Years.

    PubMed

    Seematter-Bagnoud, Laurence; Büla, Christophe; Santos-Eggimann, Brigitte

    2016-01-01

    Objectives. This study aimed to describe the cross-sectional and longitudinal association between alcohol intake and gait parameters in older persons. Methods. Community-dwelling persons aged 65-70 years (N = 807). Information on health, functional status, and alcohol use was self-reported at baseline and at 3-year follow-up, whereas gait speed and stride-to-stride variability were measured while walking only (single task) and under dual tasking (counting backwards). Results. Compared to light-to-moderate drinking, heavy drinking was associated with slower gait speed in single task (adj. coeff.: -.040, 95% CI: -.0.78 to -.002, p = .035). No significant association was observed between heavy drinking and gait speed variability. Nondrinkers walked significantly slower than light-to-moderate drinkers in dual task and had significantly higher gait speed variability in both single and dual task, but these associations disappeared after adjustment for comorbidity. At follow-up, 35.2% and 34.1% of the participants walked significantly slower in single and dual task, respectively. This proportion varied a little across drinking categories. Conclusion. At baseline, heavy alcohol consumption was significantly associated with slower gait speed in single task. Selective survival of the fittest heavy drinkers probably explains why this association faded in longitudinal analyses. The trend of poorer gait performance in nondrinkers disappeared after adjustment for comorbidity, suggesting confounding by a worse health status. PMID:27516773

  17. Multi-muscle synergies in a dual postural task: evidence for the principle of superposition

    PubMed Central

    Klous, Miriam; Danna-dos-Santos, Alessander

    2010-01-01

    We used the framework of the uncontrolled manifold hypothesis to quantify multi-muscle synergies stabilizing the moment of force about the frontal axis (MY) and the shear force in the anterior–posterior direction (FX) during voluntary body sway performed by standing subjects. We tested a hypothesis whether the controller could stabilize both MY and FX at the same time when the task and the visual feedback was provided only on one of the variables (MY). Healthy young subjects performed voluntary body sway in the anterior–posterior direction while different loads were attached at the ankle level producing horizontal forces acting forward or backwards. Principal component analysis was used to identify three M-modes within the space of integrated indices of muscle activation. Variance in the M-mode space across sway cycles was partitioned into two components, one that did not affect a selected performance variable (MY or FX) and the other that did. Under all loading conditions and for each performance variable, a higher value for the former variance component was found. We interpret these results as reflections of two multi-M-mode synergies stabilizing both FX and MY. The indices of synergies were modulated within the sway cycle; both performance variables were better stabilized when the body moved forward than when it moved backward. The results show that the controller can use a set of three elemental variables (M-modes) to stabilize two performance variables at the same time. No negative interference was seen between the synergy indices computed for the two performance variables supporting the principle of superposition with respect to multi-muscle postural control. PMID:20047089

  18. Variability of human gait: effect of backward walking and dual-tasking on the presence of long-range autocorrelations.

    PubMed

    Bollens, Benjamin; Crevecoeur, Frédéric; Detrembleur, Christine; Warlop, Thibault; Lejeune, Thierry M

    2014-04-01

    Information from the central and peripheral nervous systems is continuously integrated to produce a stable gait pattern. However, stride duration fluctuates in a complex manner in healthy subjects, exhibiting long-range autocorrelations that can span over hundreds of consecutive strides. The present study was conducted to explore the mechanisms controlling the long-term fluctuation dynamics of gait. In the first part of the study, stride duration variability was evaluated on a treadmill during forward (FW) and backward walking (BW). Despite the modification of the biomechanical constraints imposed on the locomotor system, the characteristics of the long-range autocorrelations remained unchanged in both modes of locomotion (FW: H = 0.79 ± 0.04 and α = 0.58 ± 0.13; BW: H = 0.79 ± 0.11 and α = 0.53 ± 0.25). In the second part of the study, stride duration variability was assessed while the subjects were performing a dual-task paradigm that combined gait and mental calculation. The long-term variability of stride duration was similar during usual walking (H = 0.80 ± 0.06 and α = 0.57 ± 0.13) and in dual-tasking (H = 0.77 ± 0.06 and α = 0.52 ± 0.16), whereas walking altered the performance of the cognitive task. Hence, the biomechanical and cognitive interferences imposed in the present study were not sufficient to induce a modification of the long-range autocorrelations highlighted in walking variability. These observations underline the robustness of the long-range autocorrelations. PMID:24366525

  19. Engine performance analysis and optimization of a dual-mode scramjet with varied inlet conditions

    NASA Astrophysics Data System (ADS)

    Tian, Lu; Chen, Li-Hong; Chen, Qiang; Zhong, Feng-Quan; Chang, Xin-Yu

    2016-02-01

    A dual-mode scramjet can operate in a wide range of flight conditions. Higher thrust can be generated by adopting suitable combustion modes. Based on the net thrust, an analysis and preliminary optimal design of a kerosene-fueled parameterized dual-mode scramjet at a crucial flight Mach number of 6 were investigated by using a modified quasi-one-dimensional method and simulated annealing strategy. Engine structure and heat release distributions, affecting the engine thrust, were chosen as analytical parameters for varied inlet conditions (isolator entrance Mach number: 1.5-3.5). Results show that different optimal heat release distributions and structural conditions can be obtained at five different inlet conditions. The highest net thrust of the parameterized dual-mode engine can be achieved by a subsonic combustion mode at an isolator entrance Mach number of 2.5. Additionally, the effects of heat release and scramjet structure on net thrust have been discussed. The present results and the developed analytical method can provide guidance for the design and optimization of high-performance dual-mode scramjets.

  20. Performance under dichoptic versus binocular viewing conditions - Effects of attention and task requirements

    NASA Technical Reports Server (NTRS)

    Kimchi, Ruth; Gopher, Daniel; Rubin, Yifat; Raij, David

    1993-01-01

    Three experiments investigated subjects' ability to allocate attention and cope with task requirements under dichoptic versus binocular viewing conditions. Experiments 1 and 2 employed a target detection task in compound and noncompound stimuli, and Experiment 3 employed a relative-proximity judgment task. The tasks were performed in a focused attention condition in which subjects had to attend to the stimulus presented to one eye or field (under dichoptic and binocular viewing conditions, respectively) while ignoring the stimulus presented to the other eye or field, and in a divided attention condition in which subjects had to attend to the stimuli presented to both eyes or fields. Subjects' performance was affected by the interaction of attention conditions with task requirements, but it was generally the same under dichoptic and binocular viewing conditions. The more dependent the task was on finer discrimination, the more performance was impaired by divided attention. These results suggest that at least with discrete tasks and relatively short exposure durations, performance when each eye is presented with a separate stimulus is the same as when the entire field of stimulation is viewed by both eyes.

  1. Who is talking in backward crosstalk? Disentangling response- from goal-conflict in dual-task performance.

    PubMed

    Janczyk, Markus; Pfister, Roland; Hommel, Bernhard; Kunde, Wilfried

    2014-07-01

    Responses in the second of two subsequently performed tasks can speed up compatible responses in the temporally preceding first task. Such backward crosstalk effects (BCEs) represent a challenge to the assumption of serial processing in stage models of human information processing, because they indicate that certain features of the second response have to be represented before the first response is emitted. Which of these features are actually relevant for BCEs is an open question, even though identifying these features is important for understanding the nature of parallel and serial response selection processes in dual-task performance. Motivated by effect-based models of action control, we show in three experiments that the BCE to a considerable degree reflects features of intended action effects, although features of the response proper (or response-associated kinesthetic feedback) also seem to play a role. These findings suggest that the codes of action effects (or action goals) can become activated simultaneously rather than serially, thereby creating BCEs.

  2. Using dual-process theory and analogical transfer to explain facilitation on a hypothetico-deductive reasoning task.

    PubMed

    Koenig, Cynthia S; Platt, Richard D; Griggs, Richard A

    2007-07-01

    Using the analogical transfer paradigm, the present study investigated the competing explanations of Girotto and Legrenzi (Psychological Research 51: 129-135, 1993) and Griggs, Platt, Newstead, and Jackson (Thinking and Reasoning 4: 1-14, 1998) for facilitation on the SARS version of the THOG problem, a hypothetico-deductive reasoning task. Girotto and Legrenzi argue that facilitation is based on logical analysis of the task [System 2 reasoning in Evans's (Trends in Cognitive Sciences 7: 454-459, 2003) dual-process account of reasoning] while Griggs et al. maintain that facilitation is due to an attentional heuristic produced by the wording of the problem (System 1 reasoning). If Girotto and Legrenzi are correct, then System 2 reasoning, which is volitional and responsible for deductive reasoning, should be elicited, and participants should comprehend the solution principle of the THOG task and exhibit analogical transfer. However, if Griggs et al. are correct, then System 1 reasoning, which is responsible for heuristic problem solving strategies such as an attentional heuristic, should occur, and participants should not abstract the solution principle and transfer should not occur. Significant facilitation (68 and 82% correct) was only observed for the two SARS source problems, but significant analogical transfer did not occur. This lack of transfer suggests that System 1 reasoning was responsible for the facilitation observed in the SARS problem, supporting Griggs et al.'s attentional heuristic explanation. The present results also underscore the explanatory value of using analogical transfer rather than facilitation as the criterion for problem understanding.

  3. Mapping Introspection's Blind Spot: Reconstruction of Dual-Task Phenomenology Using Quantified Introspection

    ERIC Educational Resources Information Center

    Marti, Sebastien; Sackur, Jerome; Sigman, Mariano; Dehaene, Stanislas

    2010-01-01

    Psychologists often dismiss introspection as an inappropriate measure, yet subjects readily volunteer detailed descriptions of the time and effort that they spent on a task. Are such reports really so inaccurate? We asked subjects to perform a psychological refractory period experiment followed by extensive quantified introspection. On each trial,…

  4. Modeling Parallelization and Flexibility Improvements in Skill Acquisition: From Dual Tasks to Complex Dynamic Skills

    ERIC Educational Resources Information Center

    Taatgen, Niels

    2005-01-01

    Emerging parallel processing and increased flexibility during the acquisition of cognitive skills form a combination that is hard to reconcile with rule-based models that often produce brittle behavior. Rule-based models can exhibit these properties by adhering to 2 principles: that the model gradually learns task-specific rules from instructions…

  5. Perceiving and Remembering Events Cross-Linguistically: Evidence from Dual-Task Paradigms

    ERIC Educational Resources Information Center

    Trueswell, John C.; Papafragou, Anna

    2010-01-01

    What role does language play during attention allocation in perceiving and remembering events? We recorded adults' eye movements as they studied animated motion events for a later recognition task. We compared native speakers of two languages that use different means of expressing motion (Greek and English). In Experiment 1, eye movements revealed…

  6. Working Memory in Nonsymbolic Approximate Arithmetic Processing: A Dual-Task Study with Preschoolers

    ERIC Educational Resources Information Center

    Xenidou-Dervou, Iro; van Lieshout, Ernest C. D. M.; van der Schoot, Menno

    2014-01-01

    Preschool children have been proven to possess nonsymbolic approximate arithmetic skills before learning how to manipulate symbolic math and thus before any formal math instruction. It has been assumed that nonsymbolic approximate math tasks necessitate the allocation of Working Memory (WM) resources. WM has been consistently shown to be an…

  7. Cancel and rethink in the Wason selection task: further evidence for the heuristic-analytic dual process theory.

    PubMed

    Wada, Kazushige; Nittono, Hiroshi

    2004-06-01

    The reasoning process in the Wason selection task was examined by measuring card inspection times in the letter-number and drinking-age problems. 24 students were asked to solve the problems presented on a computer screen. Only the card touched with a mouse pointer was visible, and the total exposure time of each card was measured. Participants were allowed to cancel their previous selections at any time. Although rethinking was encouraged, the cards once selected were rarely cancelled (10% of the total selections). Moreover, most of the cancelled cards were reselected (89% of the total cancellations). Consistent with previous findings, inspection times were longer for selected cards than for nonselected cards. These results suggest that card selections are determined largely by initial heuristic processes and rarely reversed by subsequent analytic processes. The present study gives further support for the heuristic-analytic dual process theory.

  8. What is Still Working in Working Memory in Old Age: Dual Tasking and Resistance to Interference Do Not Explain Age-Related Item Loss After a Focus Switch

    PubMed Central

    2013-01-01

    Objectives. In 2 experiments, we examined the oft-replicated finding of age-related differences in accuracy at retrieving items stored in working memory, but outside the focus of attention. Specifically, we investigated whether such differences could be explained by (a) age-related differences in coping with the dual-task nature of swapping items into and out of the focus of attention and/or (b) age-related differences in resistance to interference. Method. We used a modified version of the N-Back task with stimuli of different levels of difficulty, and experimental manipulations aimed at isolating the dual-task and interference effects. Results. We found both explanations lacking: We obtained a dual-task cost (Experiment 1) and an interference cost (Experiment 2), as well as a large age effect (Cohen’s d = 1.6 in Experiment 1 and 0.7 in Experiment 2) but neither the dual task nor the interference effect was sensitive to age. Discussion. These findings, combined with previous failures to find an explanation for the age effects, suggest that item availability after a focus switch might be an important new and fundamental variable—a cognitive primitive—potentially necessary for a full understanding of age effects in higher order cognition. PMID:23254887

  9. 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

  10. Effects of contextual interference and conditions of movement task on acquisition, retention, and transfer of motor skills by women.

    PubMed

    Jarus, T; Wughalter, E H; Gianutsos, J G

    1997-02-01

    This experiment was designed to investigate varying conditions of contextual interference within two different conditions of movement tasks during acquisition on the acquisition and retention of a computerized task and transfer to a functional skill. Performance of head movements was conducted under open- or closed-task conditions and with random or blocked schedules of practice. Analysis indicated that learning under the open-task condition resulted in better retention and transfer than the closed-task condition. It is suggested that increasing the within-trial variability in the open-task condition produced a contextual interference effect. In this regard, support for Battig's predictions is provided by the current findings in that the high variability present during the open-task condition was more beneficial for retention and transfer than the low variability present during the closed-task condition. Differences between random and blocked schedules of practice on the retention and transfer data were not statistically significant. PMID:9132708

  11. Evaluating the Effort Expended to Understand Speech in Noise Using a Dual-Task Paradigm: The Effects of Providing Visual Speech Cues

    ERIC Educational Resources Information Center

    Fraser, Sarah; Gagne, Jean-Pierre; Alepins, Majolaine; Dubois, Pascale

    2010-01-01

    Purpose: Using a dual-task paradigm, 2 experiments (Experiments 1 and 2) were conducted to assess differences in the amount of listening effort expended to understand speech in noise in audiovisual (AV) and audio-only (A-only) modalities. Experiment 1 had equivalent noise levels in both modalities, and Experiment 2 equated speech recognition…

  12. Deficits in Interval Timing Measured by the Dual-Task Paradigm among Children and Adolescents with Attention-Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Hwang, Shoou-Lian; Gau, Susan Shur-Fen; Hsu, Wen-Yau; Wu, Yu-Yu

    2010-01-01

    Background: The underlying mechanism of time perception deficit in long time intervals in attention-deficit/hyperactivity disorder (ADHD) is still unclear. This study used the time reproduction dual task to explore the role of the attentional resource in time perception deficits among children and adolescents with ADHD. Methods: Participants…

  13. Rethinking of the heuristic-analytic dual process theory: a comment on Wada and Nittono (2004) and the reasoning process in the Wason selection task.

    PubMed

    Cardaci, Maurizio; Misuraca, Raffaella

    2005-08-01

    This paper raises some methodological problems in the dual process explanation provided by Wada and Nittono for their 2004 results using the Wason selection task. We maintain that the Nittono rethinking approach is weak and that it should be refined to grasp better the evidence of analytic processes.

  14. Solar photocatalytic hydrogen production from water using a dual bed photosystem. Task 2 report; Annual report

    SciTech Connect

    Linkous, C.A.; McKaige, G.T.; Slattery, D.K.; Ouellette, A.J.A.; Austin, B.C.N.

    1995-12-01

    This work is an investigation into the use of photocatalytic particles in a dual bed configuration, so as to effect the solar-driven decomposition of water to its constituent elements, particularly hydrogen. The system envisioned would consist of two modules, each consisting of a shallow, flat, sealed container, in which micron-sized photocatalytic particles are immobilized. An aqueous solution containing a redox mediator is pumped between the two chambers. Different photoparticles and catalysts are chosen for their respective modules so as to effect oxidative water-splitting in one vessel to evolve oxygen gas, and reductive water-splitting in the other to evolve hydrogen. This is a direct photoconversion scheme that breaks down the energetic requirement for water decomposition into a 2-photon process, and enables separate production of hydrogen and oxygen. Titanium dioxide, TiO{sub 2}, and indium phosphide, InP, were employed as photoparticles in the O{sub 2}- and H{sub 2}-evolving beds, respectively. Platinum catalysts were evaluated to prompt H{sub 2}-evolution. Calculations on the energy band structure of free and immobilized particles provided guidance as to how the microstructure of the particles should be configured. A series of redox mediators, spanning a range of redox potentials, were tested. While many electron donors facilitated H{sub 2}-evolution, only the most oxidizing ones enabled O{sub 2}-evolution. A single redox couple, capable of charge exchange in both modules, is desirable to avoid system design complexity.

  15. Strength of hand preference and dual task performance by common marmosets.

    PubMed

    Piddington, T; Rogers, L J

    2013-01-01

    Study of avian and piscine species has shown that animals with stronger lateralization of the brain are able to perform two tasks presented simultaneously better than can animals with weaker lateralization. We investigated whether this might apply also to primates by testing common marmosets to see whether there is a relationship between the strength of hand preference, as an indicator of strength of brain lateralization, and the ability to carry out two tasks simultaneously. A model predator was introduced into the testing room while the marmoset was foraging. Marmosets with stronger hand preferences detected the 'predator' after shorter latency than those with weaker hand preferences. Furthermore, the marmosets with stronger hand preferences produced more mobbing (tsik) vocalizations when they reacted to the predators than did those with weaker hand preferences. There was no such association between hand preference and either latency to respond to the predator or mobbing reaction when the marmosets were not foraging at the time the predator was introduced. Hence, strength of lateralization is associated with the ability to perform foraging and predator detection simultaneously. These results are discussed with reference to the evolution of brain lateralization. PMID:23053795

  16. MAINTAINING TASK BEHAVIOR IN A LITERACY PROGRAM UNDER VARIOUS CONDITIONS OF REINFORCEMENT.

    ERIC Educational Resources Information Center

    SMITH, DONALD E.P.; AND OTHERS

    THE WORK OUTPUT OF RETARDED READERS USING A PROGRAMED LITERACY CURRICULUM WAS OBSERVED UNDER VARIOUS CONDITIONS OF REINFORCEMENT IN A CONTROLLED CLASSROOM. TASK BEHAVIOR WAS FOLLOWED BY CONDITIONS OF NO CONSEQUENCE, TEACHER PRAISE, A WORK-BREAK CONSEQUENCE, A MONETARY CONSEQUENCE, AND FEEDBACK ON AMOUNT OF WORK RELATIVE TO PREVIOUS WORK. SIX…

  17. Interaction of Reinforcement Conditions and Developmental Level in a Two-Choice Discrimination Task with Children

    ERIC Educational Resources Information Center

    Tindall, Robert C.; Ratliff, Richard G.

    1974-01-01

    Reports a study of 540 first-, fourth-, and eighth-grade students who participated in a discrimination task under three reinforcement conditions: reward, punishment and a combination of both. Results indicate the superiority of learning under punishment conditions. Interactions involving the sex of subject and experimenter are also discussed.…

  18. Task-related functional connectivity in autism spectrum conditions: an EEG study using wavelet transform coherence

    PubMed Central

    2013-01-01

    Background Autism Spectrum Conditions (ASC) are a set of pervasive neurodevelopmental conditions characterized by a wide range of lifelong signs and symptoms. Recent explanatory models of autism propose abnormal neural connectivity and are supported by studies showing decreased interhemispheric coherence in individuals with ASC. The first aim of this study was to test the hypothesis of reduced interhemispheric coherence in ASC, and secondly to investigate specific effects of task performance on interhemispheric coherence in ASC. Methods We analyzed electroencephalography (EEG) data from 15 participants with ASC and 15 typical controls, using Wavelet Transform Coherence (WTC) to calculate interhemispheric coherence during face and chair matching tasks, for EEG frequencies from 5 to 40 Hz and during the first 400 ms post-stimulus onset. Results Results demonstrate a reduction of interhemispheric coherence in the ASC group, relative to the control group, in both tasks and for all electrode pairs studied. For both tasks, group differences were generally observed after around 150 ms and at frequencies lower than 13 Hz. Regarding within-group task comparisons, while the control group presented differences in interhemispheric coherence between faces and chairs tasks at various electrode pairs (FT7-FT8, TP7-TP8, P7-P8), such differences were only seen for one electrode pair in the ASC group (T7-T8). No significant differences in EEG power spectra were observed between groups. Conclusions Interhemispheric coherence is reduced in people with ASC, in a time and frequency specific manner, during visual perception and categorization of both social and inanimate stimuli and this reduction in coherence is widely dispersed across the brain. Results of within-group task comparisons may reflect an impairment in task differentiation in people with ASC relative to typically developing individuals. Overall, the results of this research support the value of WTC in examining the time

  19. Dual Hypervalent Iodine(III) Reagents and Photoredox Catalysis Enable Decarboxylative Ynonylation under Mild Conditions.

    PubMed

    Huang, Hanchu; Zhang, Guojin; Chen, Yiyun

    2015-06-26

    A combination of hypervalent iodine(III) reagents (HIR) and photoredox catalysis with visible light has enabled chemoselective decarboxylative ynonylation to construct ynones, ynamides, and ynoates. This ynonylation occurs effectively under mild reaction conditions at room temperature and on substrates with various sensitive and reactive functional groups. The reaction represents the first HIR/photoredox dual catalysis to form acyl radicals from α-ketoacids, followed by an unprecedented acyl radical addition to HIR-bound alkynes. Its efficient construction of an mGlu5 receptor inhibitor under neutral aqueous conditions suggests future visible-light-induced biological applications.

  20. Spatial representations in dorsal hippocampal neurons during a tactile-visual conditional discrimination task.

    PubMed

    Griffin, Amy L; Owens, Cullen B; Peters, Gregory J; Adelman, Peter C; Cline, Kathryn M

    2012-02-01

    Trajectory-dependent coding in dorsal CA1 of hippocampus has been evident in various spatial memory tasks aiming to model episodic memory. Hippocampal neurons are considered to be trajectory-dependent if the neuron has a place field located on an overlapping segment of two trajectories and exhibits a reliable difference in firing rate between the two trajectories. It is unclear whether trajectory-dependent coding in hippocampus is a mechanism used by the rat to solve spatial memory tasks. A first step in answering this question is to compare results between studies using tasks that require spatial working memory and those that do not. We recorded single units from dorsal CA1 of hippocampus during performance of a discrete-trial, tactile-visual conditional discrimination (CD) task in a T-maze. In this task, removable floor inserts that differ in texture and appearance cue the rat to visit either the left or right goal arm to receive a food reward. Our goal was to assess whether trajectory coding would be evident in the CD task. Our results show that trajectory coding was rare in the CD task, with only 12 of 71 cells with place fields on the maze stem showing a significant firing rate difference between left and right trials. For comparison, we recorded from dorsal CA1 during the acquisition and performance of a continuous spatial alternation task identical to that used in previous studies and found a proportion of trajectory coding neurons similar to what has been previously reported. Our data suggest that trajectory coding is not a universal mechanism used by the hippocampus to disambiguate similar trajectories, and instead may be more likely to appear in tasks that require the animal to retrieve information about a past trajectory, particularly in tasks that are continuous rather than discrete in nature.

  1. Rotating objects to determine orientation, not identity: evidence from a backward-masking/dual-task procedure.

    PubMed

    De Caro, S A; Reeves, A

    2000-10-01

    The effects of picture-plane rotations on times taken to name familiar objects (RTs) may reflect a process of mental rotation to stored viewpoint-specific representations: the rotate-to-recognize hypothesis. Alternatively, mental rotation might be used after stored object representations are activated by a misoriented stimulus in order to verify a weak or distorted shape percept: the double-checking hypothesis. We tested these two accounts of rotation effects in object recognition by having subjects verify the orientations (to within 90 degrees) and basic-level names of 14-msec, backward-masked depictions of common objects. The stimulus-mask interval (SOA) varied from 14 to 41 msec, permitting interpolation of the SOA required for 75% accuracy (SOAc). Whereas the SOAc to verify orientation increased with rotation up to 180 degrees, the SOAc to verify identity was briefer and asymptoted at approximately 60 degrees. We therefore reject the rotate-to-recognize hypothesis, which implies that SOAc should increase steadily with rotation in both tasks. Instead, we suggest that upright and near-upright stimuli are matched by a fast direct process and that misoriented stimuli are matched at a featural level by a slightly slower view-independent process. We also suggest that rotation effects on RTs reflect a postrecognition stage of orientation verification: the rotate-to-orient hypothesis, a version of double-checking that also explains the well-known reduction in orientation effects on RTs when naming repeated objects. PMID:11143448

  2. A functional near-infrared spectroscopy study of lexical decision task supports the dual route model and the phonological deficit theory of dyslexia.

    PubMed

    Sela, Itamar; Izzetoglu, Meltem; Izzetoglu, Kurtulus; Onaral, Banu

    2014-01-01

    The dual route model (DRM) of reading suggests two routes of reading development: the phonological and the orthographic routes. It was proposed that although the two routes are active in the process of reading; the first is more involved at the initial stages of reading acquisition, whereas the latter needs more reading training to mature. A number of studies have shown that deficient phonological processing is a core deficit in developmental dyslexia. According to the DRM, when the Lexical Decision Task (LDT) is performed, the orthographic route should also be involved when decoding words, whereas it is clear that when decoding pseudowords the phonological route should be activated. Previous functional near-infrared spectroscopy (fNIR) studies have suggested that the upper left frontal lobe is involved in decision making in the LDT. The current study used fNIR to compare left frontal lobe activity during LDT performance among three reading-level groups: 12-year-old children, young adult dyslexic readers, and young adult typical readers. Compared to typical readers, the children demonstrated lower activity under the word condition only, whereas the dyslexic readers showed lower activity under the pseudoword condition only. The results provide evidence for upper left frontal lobe involvement in LDT and support the DRM and the phonological deficit theory of dyslexia.

  3. Dual Effects on Choice of Conditioned Reinforcement Frequency and Conditioned Reinforcement Value

    ERIC Educational Resources Information Center

    McDevitt, Margaret A.; Williams, Ben A.

    2010-01-01

    Pigeons were presented with a concurrent-chains schedule in which the total time to primary reinforcement was equated for the two alternatives (VI 30 s VI 60 s vs. VI 60 s VI 30 s). In one set of conditions, the terminal links were signaled by the same stimulus, and in another set of conditions they were signaled by different stimuli. Choice was…

  4. Condition Monitoring of Cables Task 3 Report: Condition Monitoring Techniques for Electric Cables

    SciTech Connect

    Villaran, M.; Lofaro, R.; na

    2009-11-30

    For more than 20 years the NRC has sponsored research studying electric cable aging degradation, condition monitoring, and environmental qualification testing practices for electric cables used in nuclear power plants. This report summarizes several of the most effective and commonly used condition monitoring techniques available to detect damage and measure the extent of degradation in electric cable insulation. The technical basis for each technique is summarized, along with its application, trendability of test data, ease of performing the technique, advantages and limitations, and the usefulness of the test results to characterize and assess the condition of electric cables.

  5. Simultaneous Training on Two Hippocampus-Dependent Tasks Facilitates Acquisition of Trace Eyeblink Conditioning

    ERIC Educational Resources Information Center

    Lee, Grace; Disterhoft, John F.; Kuo, Amy G.

    2006-01-01

    A common cellular alteration, reduced post-burst afterhyperpolarization (AHP) in CA1 neurons, is associated with acquisition of the hippocampus-dependent tasks trace eyeblink conditioning and the Morris water maze. As a similar increase in excitability is correlated with these two learning paradigms, we sought to determine the interactive…

  6. Probabilistic conditional reasoning: Disentangling form and content with the dual-source model.

    PubMed

    Singmann, Henrik; Klauer, Karl Christoph; Beller, Sieghard

    2016-08-01

    The present research examines descriptive models of probabilistic conditional reasoning, that is of reasoning from uncertain conditionals with contents about which reasoners have rich background knowledge. According to our dual-source model, two types of information shape such reasoning: knowledge-based information elicited by the contents of the material and content-independent information derived from the form of inferences. Two experiments implemented manipulations that selectively influenced the model parameters for the knowledge-based information, the relative weight given to form-based versus knowledge-based information, and the parameters for the form-based information, validating the psychological interpretation of these parameters. We apply the model to classical suppression effects dissecting them into effects on background knowledge and effects on form-based processes (Exp. 3) and we use it to reanalyse previous studies manipulating reasoning instructions. In a model-comparison exercise, based on data of seven studies, the dual-source model outperformed three Bayesian competitor models. Overall, our results support the view that people make use of background knowledge in line with current Bayesian models, but they also suggest that the form of the conditional argument, irrespective of its content, plays a substantive, yet smaller, role. PMID:27416493

  7. Probabilistic conditional reasoning: Disentangling form and content with the dual-source model.

    PubMed

    Singmann, Henrik; Klauer, Karl Christoph; Beller, Sieghard

    2016-08-01

    The present research examines descriptive models of probabilistic conditional reasoning, that is of reasoning from uncertain conditionals with contents about which reasoners have rich background knowledge. According to our dual-source model, two types of information shape such reasoning: knowledge-based information elicited by the contents of the material and content-independent information derived from the form of inferences. Two experiments implemented manipulations that selectively influenced the model parameters for the knowledge-based information, the relative weight given to form-based versus knowledge-based information, and the parameters for the form-based information, validating the psychological interpretation of these parameters. We apply the model to classical suppression effects dissecting them into effects on background knowledge and effects on form-based processes (Exp. 3) and we use it to reanalyse previous studies manipulating reasoning instructions. In a model-comparison exercise, based on data of seven studies, the dual-source model outperformed three Bayesian competitor models. Overall, our results support the view that people make use of background knowledge in line with current Bayesian models, but they also suggest that the form of the conditional argument, irrespective of its content, plays a substantive, yet smaller, role.

  8. Prefrontal Single-Neuron Responses after Changes in Task Contingencies during Trace Eyeblink Conditioning in Rabbits

    PubMed Central

    2016-01-01

    Abstract A number of studies indicate that the medial prefrontal cortex (mPFC) plays a role in mediating the expression of behavioral responses during tasks that require flexible changes in behavior. During trace eyeblink conditioning, evidence suggests that the mPFC provides the cerebellum with a persistent input to bridge the temporal gap between conditioned and unconditioned stimuli. Therefore, the mPFC is in a position to directly mediate the expression of trace conditioned responses. However, it is unknown whether persistent neural responses are associated with the flexible expression of behavior when task contingencies are changed during trace eyeblink conditioning. To investigate this, single-unit activity was recorded in the mPFC of rabbits during extinction and reacquisition of trace eyeblink conditioning, and during training to a different conditional stimulus. Persistent responses remained unchanged after full extinction, and also did not change during reacquisition training. During training to a different tone, however, the generalization of persistent responses to the new stimulus was associated with an animal’s performance—when persistent responses generalized to the new tone, performance was high (>50% response rate). When persistent responses decreased to baseline rates, performance was poor (<50% response rate). The data suggest that persistent mPFC responses do not appear to mediate flexible changes in the expression of the original learning, but do appear to play a role in the generalization of that learning when the task is modified. PMID:27517083

  9. Prefrontal Single-Neuron Responses after Changes in Task Contingencies during Trace Eyeblink Conditioning in Rabbits.

    PubMed

    Siegel, Jennifer J

    2016-01-01

    A number of studies indicate that the medial prefrontal cortex (mPFC) plays a role in mediating the expression of behavioral responses during tasks that require flexible changes in behavior. During trace eyeblink conditioning, evidence suggests that the mPFC provides the cerebellum with a persistent input to bridge the temporal gap between conditioned and unconditioned stimuli. Therefore, the mPFC is in a position to directly mediate the expression of trace conditioned responses. However, it is unknown whether persistent neural responses are associated with the flexible expression of behavior when task contingencies are changed during trace eyeblink conditioning. To investigate this, single-unit activity was recorded in the mPFC of rabbits during extinction and reacquisition of trace eyeblink conditioning, and during training to a different conditional stimulus. Persistent responses remained unchanged after full extinction, and also did not change during reacquisition training. During training to a different tone, however, the generalization of persistent responses to the new stimulus was associated with an animal's performance-when persistent responses generalized to the new tone, performance was high (>50% response rate). When persistent responses decreased to baseline rates, performance was poor (<50% response rate). The data suggest that persistent mPFC responses do not appear to mediate flexible changes in the expression of the original learning, but do appear to play a role in the generalization of that learning when the task is modified. PMID:27517083

  10. Speech Skill Learning of Persons Who Stutter and Fluent Speakers under Single and Dual Task Conditions

    ERIC Educational Resources Information Center

    Smits-Bandstra, Sarah; De Nil, Luc

    2009-01-01

    Two studies compared the accuracy and efficiency of initiating oral reading of nonsense syllables by persons who stutter (PWS) and fluent speakers (PNS) over practise. Findings of Study One, comparing 12 PWS and 12 PNS, replicated previous findings of slow speech sequence initiation over practise by PWS relative to PNS. In Study Two, nine PWS and…

  11. Mental rotation impairs attention shifting and short-term memory encoding: neurophysiological evidence against the response-selection bottleneck model of dual-task performance.

    PubMed

    Pannebakker, Merel M; Jolicœur, Pierre; van Dam, Wessel O; Band, Guido P H; Ridderinkhof, K Richard; Hommel, Bernhard

    2011-09-01

    Dual tasks and their associated delays have often been used to examine the boundaries of processing in the brain. We used the dual-task procedure and recorded event-related potentials (ERPs) to investigate how mental rotation of a first stimulus (S1) influences the shifting of visual-spatial attention to a second stimulus (S2). Visual-spatial attention was monitored by using the N2pc component of the ERP. In addition, we examined the sustained posterior contralateral negativity (SPCN) believed to index the retention of information in visual short-term memory. We found modulations of both the N2pc and the SPCN, suggesting that engaging mechanisms of mental rotation impairs the deployment of visual-spatial attention and delays the passage of a representation of S2 into visual short-term memory. Both results suggest interactions between mental rotation and visual-spatial attention in capacity-limited processing mechanisms indicating that response selection is not pivotal in dual-task delays and all three processes are likely to share a common resource like executive control.

  12. Viewing time effects revisited: prolonged response latencies for sexually attractive targets under restricted task conditions.

    PubMed

    Imhoff, Roland; Schmidt, Alexander F; Nordsiek, Uta; Luzar, Charlotte; Young, Andrew W; Banse, Rainer

    2010-12-01

    Sexually attractive stimuli are watched longer than unattractive stimuli. The processes underlying this robust and reliable viewing time effect are presently not well understood. In the present research comprising four experiments (total N = 250), four classes of potential explanations are proposed and the derived implications were experimentally tested. Contrary to explanations based on either deliberate delay or attentional adhesion to sexually attractive stimuli, prolonged response latencies were also found under restricted task conditions. Sexually preferred targets elicited longer response latencies in a self-paced evaluation task when stimulus pictures were presented for 750 ms (Experiment 1) or for 500 ms and followed by a pattern mask (Experiment 2). Prolonged latencies for sexually preferred targets were also observed when sexual attractiveness was rated in a speeded binary decision task with a response window of 1000 ms (Experiment 3). Eventually, it was shown that the response latency effect in the speeded binary choice task was still preserved when only the heads of target individuals were presented instead of the bodies (Experiment 4). Mate identification and schematic processes are discussed as the remaining plausible mechanisms for prolonged response latencies for sexually attractive targets under restricted conditions. PMID:20198414

  13. The Effects of Varied Extinction Conditions Following Acquisition on a 100 Per Cent Rewarded Task in Alcoholics and Nonalcoholics.

    ERIC Educational Resources Information Center

    Okultich, Peter V.; Marlatt, G. Alan

    The purpose of this study was two-fold: (1) to determine whether alcoholics will show greater persistance in responding under punishment in a simple operant task as compared to nonalcoholics; and (2) with this task, under what conditions alcoholics will suppress their responses to the same extent as nonalcoholics. In the task, all subjects during…

  14. More evidence for a dual-process model of conditional reasoning.

    PubMed

    Markovits, Henry; Forgues, Hugues Lortie; Brunet, Marie-Laurence

    2012-07-01

    Many studies have shown that the deductive inferences that people make have global properties that reflect the statistical information implicit in the premises. This suggests that such reasoning can be explained by a single, underlying probabilistic model. In contrast, the dual process model of conditional reasoning (Verschueren, Schaeken, & d'Ydewalle, 2005b) proposes that people can use either a logical, counterexample-based strategy or a probabilistic one. In two studies, we presented reasoners with sequences of affirmation-of-the-consequent inferences that differed with respect to the statistical properties of the premises, either explicitly or implicitly. As predicted by the dual-process model, an analysis of individual response patterns showed the presence of two distinct strategies, with use of the counterexample strategy being associated with higher levels of abstract-reasoning competence. Use of the counterexample strategy was facilitated by the explicit presentation of counterexample information. In a further study, we then examined explicitly probabilistic inferences. This study showed that although most reasoners made statistically appropriate inferences, the ability to make more-accurate inferences was associated with higher levels of abstract reasoning competence. These results show that deductive inferential reasoning cannot be explained by a single, unitary process and that any analysis of reasoning must consider individual differences in strategy use.

  15. Associations between Tactile Sensory Threshold and Postural Performance and Effects of Healthy Aging and Subthreshold Vibrotactile Stimulation on Postural Outcomes in a Simple Dual Task.

    PubMed

    Dettmer, Marius; Pourmoghaddam, Amir; Lee, Beom-Chan; Layne, Charles S

    2016-01-01

    Specific activities that require concurrent processing of postural and cognitive tasks may increase the risk for falls in older adults. We investigated whether peripheral receptor sensitivity was associated with postural performance in a dual-task and whether an intervention in form of subthreshold vibration could affect performance. Ten younger (age: 20-35 years) and ten older adults (70-85 years) performed repeated auditory-verbal 1-back tasks while standing quietly on a force platform. Foot sole vibration was randomly added during several trials. Several postural control and performance measures were assessed and statistically analyzed (significance set to α-levels of .05). There were moderate correlations between peripheral sensitivity and several postural performance and control measures (r = .45 to .59). Several postural performance measures differed significantly between older and younger adults (p < 0.05); addition of vibration did not affect outcome measures. Aging affects healthy older adults' performance in dual-tasks, and peripheral sensitivity may be a contributor to the observed differences. A vibration intervention may only be useful when there are more severe impairments of the sensorimotor system. Hence, future research regarding the efficacy of sensorimotor interventions in the form of vibrotactile stimulation should focus on older adults whose balance is significantly affected. PMID:27143967

  16. Associations between Tactile Sensory Threshold and Postural Performance and Effects of Healthy Aging and Subthreshold Vibrotactile Stimulation on Postural Outcomes in a Simple Dual Task

    PubMed Central

    Dettmer, Marius; Pourmoghaddam, Amir; Lee, Beom-Chan; Layne, Charles S.

    2016-01-01

    Specific activities that require concurrent processing of postural and cognitive tasks may increase the risk for falls in older adults. We investigated whether peripheral receptor sensitivity was associated with postural performance in a dual-task and whether an intervention in form of subthreshold vibration could affect performance. Ten younger (age: 20–35 years) and ten older adults (70–85 years) performed repeated auditory-verbal 1-back tasks while standing quietly on a force platform. Foot sole vibration was randomly added during several trials. Several postural control and performance measures were assessed and statistically analyzed (significance set to α-levels of .05). There were moderate correlations between peripheral sensitivity and several postural performance and control measures (r = .45 to .59). Several postural performance measures differed significantly between older and younger adults (p < 0.05); addition of vibration did not affect outcome measures. Aging affects healthy older adults' performance in dual-tasks, and peripheral sensitivity may be a contributor to the observed differences. A vibration intervention may only be useful when there are more severe impairments of the sensorimotor system. Hence, future research regarding the efficacy of sensorimotor interventions in the form of vibrotactile stimulation should focus on older adults whose balance is significantly affected. PMID:27143967

  17. Enhanced flue gas conditioning study. Final report for Task 7.20

    SciTech Connect

    Miller, S.J.; Laudal, D.L.

    1991-11-01

    Many electrostatic precipitators (ESPS) do not achieve acceptable particulate removal efficiencies because of high-resistivity ash. One method to improve ESP performance is to employ chemical conditioning agents to reduce fly ash resistivity. Widely used agents include sulfur trioxide (SO{sub 3}) and ammonia, which are sometimes used simultaneously. For some fly ashes, that have a low affinity for SO{sub 3}, conditioning with SO{sub 3} alone is not adequate to reduce resistivity without excessive amounts of SO{sub 3} exiting the stack. In such cases, the use of ammonia in addition to SO{sub 3} may reduce the amount of required SO{sub 3} and prevent the emission of excess SO{sub 3} out of the stack. The general objective of the work was to test enhanced flue gas conditioning methods to improve the performance of ESPS. Specific objectives were to (1) verify the relationship between the required SO{sub 3} injection rates to maintain the desired fly ash resistivity and temperature for four coals, (2) verify that dual conditioning with both ammonia and SO{sub 3} promotes SO{sub 3} utilization and allows for resistivity modification with moderate SO{sub 3} injection rates, and (3) verify the effectiveness and practicality of an enhanced flue gas conditioning (EFGC) method. The EFGC method is a proprietary development of Wahlco, Inc.

  18. The effect of emotion on interpretation and logic in a conditional reasoning task.

    PubMed

    Blanchette, Isabelle

    2006-07-01

    The effect of emotional content on logical reasoning is explored in three experiments. Theparticipants completed a conditional reasoning task (If p, then q) with emotional and neutral contents. In Experiment 1, existing emotional and neutral words were used. The emotional value of initially neutral words was experimentally manipulated in Experiments 1B and 2, using classical conditioning. In all experiments, participants were less likely to provide normatively correct answers when reasoning about emotional stimuli, compared with neutral stimuli. This was true for both negative (Experiments 1B and 2) and positive contents (Experiment 2). The participants' interpretations of the conditional statements were also measured (perceived sufficiency, necessity, causality, and plausibility). The results showed the expected relationship between interpretation and reasoning. However, emotion did not affect interpretation. Emotional and neutral conditional statements were interpreted similarly. The results are discussed in light of current models of emotion and reasoning.

  19. Application of three-class ROC analysis to task-based image quality assessment of simultaneous dual-isotope myocardial perfusion SPECT (MPS).

    PubMed

    He, Xin; Song, Xiyun; Frey, Eric C

    2008-11-01

    The diagnosis of cardiac disease using dual-isotope myocardial perfusion SPECT (MPS) is based on the defect status in both stress and rest images, and can be modeled as a three-class task of classifying patients as having no, reversible, or fixed perfusion defects. Simultaneous acquisition protocols for dual-isotope MPS imaging have gained much interest due to their advantages including perfect registration of the (201)Tl and (99m)Tc images in space and time, increased patient comfort, and higher clinical throughput. As a result of simultaneous acquisition, however, crosstalk contamination, where photons emitted by one isotope contribute to the image of the other isotope, degrades image quality. Minimizing the crosstalk is important in obtaining the best possible image quality. One way to minimize the crosstalk is to optimize the injected activity of the two isotopes by considering the three-class nature of the diagnostic problem. To effectively do so, we have previously developed a three-class receiver operating characteristic (ROC) analysis methodology that extends and unifies the decision theoretic, linear discriminant analysis, and psychophysical foundations of binary ROC analysis in a three-class paradigm. In this work, we applied the proposed three-class ROC methodology to the assessment of the image quality of simultaneous dual-isotope MPS imaging techniques and the determination of the optimal injected activity combination. In addition to this application, the rapid development of diagnostic imaging techniques has produced an increasing number of clinical diagnostic tasks that involve not only disease detection, but also disease characterization and are thus multiclass tasks. This paper provides a practical example of the application of the proposed three-class ROC analysis methodology to medical problems.

  20. Fearless Dominance and reduced feedback-related negativity amplitudes in a time-estimation task – Further neuroscientific evidence for dual-process models of psychopathy☆

    PubMed Central

    Schulreich, Stefan; Pfabigan, Daniela M.; Derntl, Birgit; Sailer, Uta

    2013-01-01

    Dual-process models of psychopathy postulate two etiologically relevant processes. Their involvement in feedback processing and its neural correlates has not been investigated so far. Multi-channel EEG was collected while healthy female volunteers performed a time-estimation task and received negative or positive feedback in form of signs or emotional faces. The affective-interpersonal factor Fearless Dominance, but not Self-Centered Impulsivity, was associated with reduced feedback-related negativity (FRN) amplitudes. This neural dissociation extends previous findings on the impact of psychopathy on feedback processing and further highlights the importance of distinguishing psychopathic traits and extending previous (neuroscientific) models of psychopathy. PMID:23607997

  1. QUALITY OR SACRIFICE? THE INFLUENCE OF DECISION TASK AND PRODUCT CHARACTERISTICS ON THE DUAL ROLE OF PRICE.

    PubMed

    Chang, Shin-Shin; Chang, Chung-Chau; Su, Wei-Gan

    2015-08-01

    People perceive price as a cue of monetary sacrifice, a quality signal, or both. However, this research proposed that the relative salience of these two roles varies with different decision tasks (i.e., selection and rejection). Furthermore, the effect of decision task type on price perception differs by product type (i.e., tangible goods or services). Two experiments show that (1) the price-quality perception under the selection task is higher than that of a rejection task for tangible goods but not for services; and (2) for goods and services, the sacrifice perception is greater in the rejection task than that in a selection task. These findings have important implications for formulating product assortment and marketing communications strategies.

  2. Deep abdominal muscle thickness measured under sitting conditions during different stability tasks

    PubMed Central

    Nagai, Hideyuki; Akasaka, Kiyokazu; Otsudo, Takahiro; Sawada, Yutaka; Okubo, Yu

    2016-01-01

    [Purpose] This study was conducted to investigate ultrasonically determined changes in the thickness of the transversus abdominis and internal oblique muscles during different sitting conditions. [Subjects and Methods] Twenty healthy men volunteered to participate in this study. Four different sitting conditions including (A) sitting, (B) sitting with left hip flexion, (C) sitting with an abdominal hollowing maneuver (AHM), and (D) sitting with an AHM and left hip flexion, were used. Subjective exercise difficulty was evaluated. [Results] Transversus abdominis and internal oblique muscle thicknesses significantly differed between conditions, with significantly greater thickness between positions from (A) to (D). Stability of the surface when sitting had no effect on the muscle thickness of the transversus abdominis. By contrast, sitting on an unstable surface caused an increase in muscle thickness of the internal oblique in each condition. The subjects reported progressively increasing difficulty in performing each exercise in a stable position from (A) to (D), while the difficulty in an unstable position was significantly different between (A) and (B), and between (C) and (D). [Conclusion] Our findings suggest that task (B) on a stable surface should be chosen for maximal activation of transversus abdominis without inducing overactivation of the internal oblique muscle. PMID:27134381

  3. A New Tool for Assessing Context Conditioning Induced by US-Unpredictability in Humans: The Martians Task Restyled

    ERIC Educational Resources Information Center

    Meulders, Ann; Vervliet, Bram; Vansteenwegen, Debora; Hermans, Dirk; Baeyens, Frank

    2011-01-01

    Unpredictability of an unconditioned stimulus (US) typically produces context conditioning in animals and humans. We modified the Martians task--a computer game measuring learning of Pavlovian associations through conditioned suppression--for assessing context conditioning in humans. One between-subjects and one within-subjects study are reported.…

  4. Performance of Cerebral Palsied Children under Conditions of Reduced Auditory Input on Selected Intellectual, Cognitive and Perceptual Tasks.

    ERIC Educational Resources Information Center

    Fassler, Joan

    The study investigated the task performance of cerebral palsied children under conditions of reduced auditory input and under normal auditory conditions. A non-cerebral palsied group was studied in a similar manner. Results indicated that cerebral palsied children showed some positive change in performance, under conditions of reduced auditory…

  5. Task Encoding across the Multiple Demand Cortex Is Consistent with a Frontoparietal and Cingulo-Opercular Dual Networks Distinction

    PubMed Central

    Mitchell, Daniel J.; Duncan, John

    2016-01-01

    Multiple-demand (MD) regions of the human brain show coactivation during many different kinds of task performance. Previous work based on resting-state functional magnetic resonance imaging (fMRI) has shown that MD regions may be divided into two closely coupled subnetworks centered around the lateral frontoparietal (FP) and cingulo-opercular cortex. Here, we used on-task fMRI to test whether this division is apparent during the performance of an executive task. Furthermore, we investigated whether there is a difference in the encoding of task between the two subnetworks. Using connectivity methods, we found that activity across the entire MD cortex is correlated during task performance. Meanwhile, however, there was significantly stronger connectivity within each of the subnetworks than between them. Using multivoxel pattern analysis, we also found that, although we were able to decode task-relevant information from all regions of the MD cortex, classification accuracy scores were significantly higher in the FP subnetwork. These results suggest a nested picture with MD regions as a whole showing coactivation and broad rule representation, but with significant functional distinctions between component subnetworks. SIGNIFICANCE STATEMENT Multiple-demand (MD) regions of frontal and parietal cortex appear essential for the orchestration of goal-directed behavior and problem solving. Understanding the relative specialization of regions within the MD cortex is crucial to understanding how we can coordinate and execute complex action plans. By examining functional connectivity during task performance, we extend previous findings suggesting that the MD cortex can be divided into two subnetworks centered around the frontoparietal (FP) and cingulo-opercular (CO) cortex. Furthermore, using multivoxel pattern analysis, we show that, compared with the CO subnetwork, the FP subnetwork manifests more differentiated coding of specific task events. PMID:27277793

  6. Applying the dual-isotope conceptual model to interpret physiological trends under uncontrolled conditions.

    PubMed

    Barnard, H R; Brooks, J R; Bond, B J

    2012-10-01

    The inter-relationships among δ(13)C and δ(18)O in tree ring cellulose and ring width have the potential to illuminate long-term physiological and environmental information in forest stands that have not been monitored. We examine how within-stand competition and environmental gradients affect ring widths and the stable isotopes of cellulose. We utilize a natural climate gradient across a catchment dominated by Douglas-fir and temporal changes in climate over an 8-year period. We apply a dual-isotope approach to infer physiological response of trees in differing crown dominance classes to temporal and spatial changes in environmental conditions using a qualitative conceptual model of the (13)C-(18)O relationship and by normalizing the data to minimize other variance. The δ(13)C and δ(18)O of cellulose were correlated with year-to-year variation in relative humidity and consistent with current isotope theory. Using a qualitative conceptual model of the (13)C-(18)O relationship and physiological knowledge about the species, we interpreted these changes as stomatal conductance responses to evaporative demand. Spatial variance between plots was not strong and seemed related to leaf nitrogen rather than any other environmental variable. Dominant trees responded to environmental gradients more consistently with current isotope theory as compared with other classes within the same stand. We found a correlation of stable isotopes with environmental variables is useful for assessing the impacts of environmental change over short time series and where growth varies only minimally with climate. PMID:22989739

  7. Hippocampal Homer1 levels influence motivational behavior in an operant conditioning task.

    PubMed

    Wagner, Klaus V; Häusl, Alexander S; Pöhlmann, Max L; Hartmann, Jakob; Labermaier, Christiana; Müller, Marianne B; Schmidt, Mathias V

    2014-01-01

    Loss of motivation and learning impairments are commonly accepted core symptoms of psychiatric disorders such as depression and schizophrenia. Reward-motivated learning is dependent on the hippocampal formation but the molecular mechanisms that lead to functional incentive motivation in this brain region are still largely unknown. Recent evidence implicates neurotransmission via metabotropic glutamate receptors and Homer1, their interaction partner in the postsynaptic density, in drug addiction and motivational learning. As previous reports mainly focused on the prefrontal cortex and the nucleus accumbens, we now investigated the role of hippocampal Homer1 in operant reward learning in the present study. We therefore tested either Homer1 knockout mice or mice that overexpress Homer1 in the hippocampus in an operant conditioning paradigm. Our results show that deletion of Homer1 leads to a diverging phenotype that either displays an inability to perform the task or outstanding hyperactivity in both learning and motivational sessions. Due to the apparent bimodal distribution of this phenotype, the overall effect of Homer1 deletion in this paradigm is not significantly altered. Overexpression of hippocampal Homer1 did not lead to a significantly altered learning performance in any stage of the testing paradigm, yet may subtly contribute to emerging motivational deficits. Our results indicate an involvement of Homer1-mediated signaling in the hippocampus in motivation-based learning tasks and encourage further investigations regarding the specific molecular underpinnings of the phenotypes observed in this study. We also suggest to cautiously interpret the results of this and other studies regarding the phenotype following Homer1 manipulations in animals, since their behavioral phenotype appears to be highly diverse. Future studies would benefit from larger group sizes that would allow splitting the experimental groups in responders and non-responders.

  8. Imaging tasks scheduling for high-altitude airship in emergency condition based on energy-aware strategy.

    PubMed

    Zhimeng, Li; Chuan, He; Dishan, Qiu; Jin, Liu; Manhao, Ma

    2013-01-01

    Aiming to the imaging tasks scheduling problem on high-altitude airship in emergency condition, the programming models are constructed by analyzing the main constraints, which take the maximum task benefit and the minimum energy consumption as two optimization objectives. Firstly, the hierarchy architecture is adopted to convert this scheduling problem into three subproblems, that is, the task ranking, value task detecting, and energy conservation optimization. Then, the algorithms are designed for the sub-problems, and the solving results are corresponding to feasible solution, efficient solution, and optimization solution of original problem, respectively. This paper makes detailed introduction to the energy-aware optimization strategy, which can rationally adjust airship's cruising speed based on the distribution of task's deadline, so as to decrease the total energy consumption caused by cruising activities. Finally, the application results and comparison analysis show that the proposed strategy and algorithm are effective and feasible. PMID:23864822

  9. Imaging Tasks Scheduling for High-Altitude Airship in Emergency Condition Based on Energy-Aware Strategy

    PubMed Central

    Zhimeng, Li; Chuan, He; Dishan, Qiu; Jin, Liu; Manhao, Ma

    2013-01-01

    Aiming to the imaging tasks scheduling problem on high-altitude airship in emergency condition, the programming models are constructed by analyzing the main constraints, which take the maximum task benefit and the minimum energy consumption as two optimization objectives. Firstly, the hierarchy architecture is adopted to convert this scheduling problem into three subproblems, that is, the task ranking, value task detecting, and energy conservation optimization. Then, the algorithms are designed for the sub-problems, and the solving results are corresponding to feasible solution, efficient solution, and optimization solution of original problem, respectively. This paper makes detailed introduction to the energy-aware optimization strategy, which can rationally adjust airship's cruising speed based on the distribution of task's deadline, so as to decrease the total energy consumption caused by cruising activities. Finally, the application results and comparison analysis show that the proposed strategy and algorithm are effective and feasible. PMID:23864822

  10. Deficits of Semantic Control Produce Absent or Reverse Frequency Effects in Comprehension: Evidence from Neuropsychology and Dual Task Methodology

    ERIC Educational Resources Information Center

    Almaghyuli, Azizah; Thompson, Hannah; Lambon Ralph, Matthew A.; Jefferies, Elizabeth

    2012-01-01

    Patients with multimodal semantic impairment following stroke (referred to here as "semantic aphasia" or SA) fail to show the standard effects of frequency in comprehension tasks. Instead, they show absent or even "reverse" frequency effects: i.e., better understanding of less common words. In addition, SA is associated with poor regulatory…

  11. Optimal kVp selection for dual-energy imaging of the chest: Evaluation by task-specific observer preference tests

    SciTech Connect

    Williams, D. B.; Siewerdsen, J. H.; Tward, D. J.; Paul, N. S.; Dhanantwari, A. C.; Shkumat, N. A.; Richard, S.; Yorkston, J.; Van Metter, R.

    2007-10-15

    Human observer performance tests were conducted to identify optimal imaging techniques in dual-energy (DE) imaging of the chest with respect to a variety of visualization tasks for soft and bony tissue. Specifically, the effect of kVp selection in low- and high-energy projection pairs was investigated. DE images of an anthropomorphic chest phantom formed the basis for observer studies, decomposed from low-energy and high-energy projections in the range 60-90 kVp and 120-150 kVp, respectively, with total dose for the DE image equivalent to that of a single chest radiograph. Five expert radiologists participated in observer preference tests to evaluate differences in image quality among the DE images. For visualization of soft-tissue structures in the lung, the [60/130] kVp pair provided optimal image quality, whereas [60/140] kVp proved optimal for delineation of the descending aorta in the retrocardiac region. Such soft-tissue detectability tasks exhibited a strong dependence on the low-kVp selection (with 60 kVp providing maximum soft-tissue conspicuity) and a weaker dependence on the high-kVp selection (typically highest at 130-140 kVp). Qualitative examination of DE bone-only images suggests optimal bony visualization at a similar technique, viz., [60/140] kVp. Observer preference was largely consistent with quantitative analysis of contrast, noise, and contrast-to-noise ratio, with subtle differences likely related to the imaging task and spatial-frequency characteristics of the noise. Observer preference tests offered practical, semiquantitative identification of optimal, task-specific imaging techniques and will provide useful guidance toward clinical implementation of high-performance DE imaging systems.

  12. Reusable task-specific ionic liquids for a clean ε-caprolactam synthesis under mild conditions.

    PubMed

    Turgis, Raphaël; Estager, Julien; Draye, Micheline; Ragaini, Vittorio; Bonrath, Werner; Lévêque, Jean-Marc

    2010-12-17

    Brønsted-acidic ionic liquids that bear a sulfonic acid group, known as Forbes acids, show a good catalytic activity for the Beckmann rearrangement, used to prepare ε-caprolactam, which is a precursor of Nylon 6. The activity essentially stems from the acidity of the sulfonic acid group. Although these task specific ionic liquids suffer from a high viscosity, this drawback can be circumvented at higher temperatures. A combination of the hydrogen sulfate anion and the sulfonic acid group of the cation is needed to obtain the rearrangement product rapidly under mild conditions. When using an excess of ionic liquid, we postulate that the internal pressure of the ionic medium, generated by the high viscosity and the high number of hydrogen-bonds, is strong enough to contribute to a decrease of the thermodynamic barrier. In accordance with the "Principles of Green Chemistry," we have developed a synthesis of ε-caprolactam that requires no additional chemicals except cyclohexanone oxime and the reusable TSIL.

  13. Generalization of Pain-Related Fear Using a Left-Right Hand Judgment Conditioning Task.

    PubMed

    Meulders, Ann; Harvie, Daniel S; Lorimer Moseley, G; Vlaeyen, Johan W S

    2015-09-01

    Recent research suggests that the mere intention to perform a painful movement can elicit pain-related fear. Based on these findings, the present study aimed to determine whether imagining a movement that is associated with pain (CS+) can start to elicit conditioned pain-related fear as well and whether pain-related fear elicited by imagining a painful movement can spread towards novel, similar but distinct imagined movements. We proposed a new experimental paradigm that integrates the left-right hand judgment task (HJT) with a differential fear conditioning procedure. During Acquisition, one hand posture (CS+) was consistently followed by a painful electrocutaneous stimulus (pain-US) and another hand posture (CS-) was not. Participants were instructed to make left-right judgments, which involve mentally rotating their own hand to match the displayed hand postures (i.e., motor imagery). During Generalization, participants were presented with a series of novel hand postures with six grades of perceptual similarity to the CS+ (generalization stimuli; GSs). Finally, during Extinction, the CS+ hand posture was no longer reinforced. The results showed that (1) a painful hand posture triggers fear and increased US-expectancy as compared to a nonpainful hand posture, (2) this pain-related fear spreads to similar but distinct hand postures following a generalization gradient, and subsequently, (3) it can be successfully reduced during extinction. These effects were apparent in the verbal ratings, but not in the startle measures. Because of the lack of effect in the startle measures, we cannot draw firm conclusions about whether the "imagined movements" (i.e., motor imagery of the hand postures) gained associative strength rather than the hand posture pictures itself. From a clinical perspective, basic research into generalization of pain-related fear triggered by covert CSs such as intentions, imagined movements and movement-related cognitions might further our

  14. Transient inactivation of the medial prefrontal cortex impairs performance on a working memory-dependent conditional discrimination task.

    PubMed

    Urban, Kimberly R; Layfield, Dylan M; Griffin, Amy L

    2014-12-01

    The rodent medial prefrontal cortex (mPFC) has been implicated in working memory function; lesions and inactivation of this region have been shown to result in impairments in spatial working memory (WM) tasks. Our laboratory has developed a tactile-visual conditional discrimination (CD) task, which uses floor insert cues to signal the correct goal-arm choice in a T maze. This task can be manipulated by altering the floor insert cues to be present throughout the trial (CDSTANDARD) or to be present only at the beginning of the trial (CDWM), thus making the task either WM-independent or WM-dependent, respectively. This ability to manipulate the working memory demand of the task while holding all other task features constant allows us to rule out the possibility that confounding performance variables contribute to the observed impairment. A previous study from our lab showed that mPFC inactivation did not impair performance on CDSTANDARD, confirming that mPFC inactivation does not induce sensorimotor or motivational deficits that could impact task performance. To examine whether mPFC inactivation impairs CDWM, the current study transiently inactivated the mPFC with bilateral microinfusions of muscimol immediately prior to testing on the CDWM task. As predicted, CDWM task performance was significantly impaired during the muscimol-infusion session compared with the control saline-infusion sessions. Together with our previous demonstration that the mPFC in not required for CDSTANDARD, these results not only confirm that the mPFC is crucial for working memory, but also set the stage for using the task-comparison approach to investigate corticolimbic interactions during working memory. PMID:25314661

  15. Student Achievement on Different Types of Tasks under Cooperative, Competitive, and Individualistic Conditions.

    ERIC Educational Resources Information Center

    Johnson, David W.; And Others

    1979-01-01

    The effects of interpersonal cooperation, competition, and individualistic efforts were compared on math and reading drill-review, story problems, sequencing, triangle identification, and visual sorting according to attributes tasks, using first-grade students. The cooperative group achieved higher scores and found the tasks easier than the…

  16. Depth of processing in the stroop task: evidence from a novel forced-reading condition.

    PubMed

    Eidels, Ami; Ryan, Kathryn; Williams, Paul; Algom, Daniel

    2014-01-01

    The presence of the Stroop effect betrays the fact that the carrier words were read in the face of instructions to ignore them and to respond to the target ink colors. In this study, we probed the nature of this involuntary reading by comparing color performance with that in a new forced-reading Stroop task in which responding is strictly contingent on reading each and every word. We found larger Stroop effects in the forced-reading task than in the classic Stroop task and concluded that words are processed to a shallower level in the Stroop task than they are in routine voluntary reading. The results show that the two modes of word processing differ in systematic ways and are conductive to qualitatively different representations. These results can pose a challenge to the strongly automatic view of word reading in the Stroop task.

  17. Dual-index evaluation of character changes in Panax ginseng C. A. Mey stored in different conditions.

    PubMed

    Li, Chen-yang; Lau, David Tai-wai; Dong, Tina Ting-xia; Zhang, Jian; Choi, Roy Chi-yan; Wu, Hai-qiang; Wang, Li-yan; Hong, Rui-sha; Li, Shi-he; Song, Xun; Yu, Tian; Su, Wei-wei; Tsim, Karl Wah-keung; He, Zhen-dan

    2013-07-01

    Panax ginseng C. A. Mey has been used as a traditional medicine and functional food in Asia for thousands of years for its improvement of human immunity and metabolism and its antitumor and antifatigue activities. This study reports the impact of storage conditions and storage period on the quality of P. ginseng. The contents of four major ginsenosides in P. ginseng and phosphorylation activities of Akt of ginseng extracts were affected by both storage conditions and storage period. In contrast, the ATP generation capacity of ginseng extracts was affected by storage conditions, but not by storage period. The results showed that the quality of P. ginseng could be well maintained at a relative humidity between 70% and 90%, and dry conditions might decrease the quality of P. ginseng. Through dual-index evaluation, the present study extended our knowledge on the changes of ginsenosides and bioactivities in P. ginseng with respect to different storage conditions and storage periods.

  18. Learning an operant conditioning task differentially induces gliogenesis in the medial prefrontal cortex and neurogenesis in the hippocampus.

    PubMed

    Rapanelli, Maximiliano; Frick, Luciana Romina; Zanutto, Bonifacio Silvano

    2011-02-18

    Circuit modification associated with learning and memory involves multiple events, including the addition and remotion of newborn cells trough adulthood. Adult neurogenesis and gliogenesis were mainly described in models of voluntary exercise, enriched environments, spatial learning and memory task; nevertheless, it is unknown whether it is a common mechanism among different learning paradigms, like reward dependent tasks. Therefore, we evaluated cell proliferation, neurogenesis, astrogliogenesis, survival and neuronal maturation in the medial prefrontal cortex (mPFC) and the hippocampus (HIPP) during learning an operant conditioning task. This was performed by using endogenous markers of cell proliferation, and a bromodeoxiuridine (BrdU) injection schedule in two different phases of learning. Learning an operant conditioning is divided in two phases: a first phase when animals were considered incompletely trained (IT, animals that were learning the task) when they performed between 50% and 65% of the responses, and a second phase when animals were considered trained (Tr, animals that completely learned the task) when they reached 100% of the responses with a latency time lower than 5 seconds. We found that learning an operant conditioning task promoted cell proliferation in both phases of learning in the mPFC and HIPP. Additionally, the results presented showed that astrogliogenesis was induced in the medial prefrontal cortex (mPFC) in both phases, however, the first phase promoted survival of these new born astrocytes. On the other hand, an increased number of new born immature neurons was observed in the HIPP only in the first phase of learning, whereas, decreased values were observed in the second phase. Finally, we found that neuronal maturation was induced only during the first phase. This study shows for the first time that learning a reward-dependent task, like the operant conditioning, promotes neurogenesis, astrogliogenesis, survival and neuronal

  19. Measuring the cognitive resources consumed per second for real-time lie-production and recollection: a dual-tasking paradigm.

    PubMed

    Hu, Chao; Huang, Kun; Hu, Xiaoqing; Liu, Yanshuo; Yuan, Fang; Wang, Qiandong; Fu, Genyue

    2015-01-01

    This research report presents a novel method of dual-tasking lie-detection. Novel software "Follow Me" was invented for a concurrent eye-hand coordination task during truth-telling/lying. Undergraduate participants were instructed to tell truths on questions about undergraduate school whereas they were instructed to tell lies on interview questions about graduate school, pretending they were graduate students. Throughout the experiment, they operated the "Follow Me" software: moving the mouse pointer to follow a randomly-moving dot on a computer screen. The distance between the mouse pointer tip and the dot center was measured by the software every 50 ms. Frequency of distance fluctuation was analyzed as the index of cognitive effort consumed per second (i.e., "degree of cognitive effort"). The results revealed that the dominant frequency of distance fluctuation was significantly lower during encoding than during retrieving responses; and lower during lying than truth-telling. Thus, dominant frequency of distance fluctuation may be an effective index of cognitive effort. Moreover, both encoding and retrieving bald-faced lies were more cognitively effortful than truth-telling. This novel definition and measurement of degree of cognitive effort may contribute to the research field of deception as well as to many other fields in social cognition.

  20. Dual learning processes underlying human decision-making in reversal learning tasks: functional significance and evidence from the model fit to human behavior.

    PubMed

    Bai, Yu; Katahira, Kentaro; Ohira, Hideki

    2014-01-01

    Humans are capable of correcting their actions based on actions performed in the past, and this ability enables them to adapt to a changing environment. The computational field of reinforcement learning (RL) has provided a powerful explanation for understanding such processes. Recently, the dual learning system, modeled as a hybrid model that incorporates value update based on reward-prediction error and learning rate modulation based on the surprise signal, has gained attention as a model for explaining various neural signals. However, the functional significance of the hybrid model has not been established. In the present study, we used computer simulation in a reversal learning task to address functional significance in a probabilistic reversal learning task. The hybrid model was found to perform better than the standard RL model in a large parameter setting. These results suggest that the hybrid model is more robust against the mistuning of parameters compared with the standard RL model when decision-makers continue to learn stimulus-reward contingencies, which can create abrupt changes. The parameter fitting results also indicated that the hybrid model fit better than the standard RL model for more than 50% of the participants, which suggests that the hybrid model has more explanatory power for the behavioral data than the standard RL model. PMID:25161635

  1. Measuring the cognitive resources consumed per second for real-time lie-production and recollection: a dual-tasking paradigm.

    PubMed

    Hu, Chao; Huang, Kun; Hu, Xiaoqing; Liu, Yanshuo; Yuan, Fang; Wang, Qiandong; Fu, Genyue

    2015-01-01

    This research report presents a novel method of dual-tasking lie-detection. Novel software "Follow Me" was invented for a concurrent eye-hand coordination task during truth-telling/lying. Undergraduate participants were instructed to tell truths on questions about undergraduate school whereas they were instructed to tell lies on interview questions about graduate school, pretending they were graduate students. Throughout the experiment, they operated the "Follow Me" software: moving the mouse pointer to follow a randomly-moving dot on a computer screen. The distance between the mouse pointer tip and the dot center was measured by the software every 50 ms. Frequency of distance fluctuation was analyzed as the index of cognitive effort consumed per second (i.e., "degree of cognitive effort"). The results revealed that the dominant frequency of distance fluctuation was significantly lower during encoding than during retrieving responses; and lower during lying than truth-telling. Thus, dominant frequency of distance fluctuation may be an effective index of cognitive effort. Moreover, both encoding and retrieving bald-faced lies were more cognitively effortful than truth-telling. This novel definition and measurement of degree of cognitive effort may contribute to the research field of deception as well as to many other fields in social cognition. PMID:25999903

  2. Measuring the cognitive resources consumed per second for real-time lie-production and recollection: a dual-tasking paradigm

    PubMed Central

    Hu, Chao; Huang, Kun; Hu, Xiaoqing; Liu, Yanshuo; Yuan, Fang; Wang, Qiandong; Fu, Genyue

    2015-01-01

    This research report presents a novel method of dual-tasking lie-detection. Novel software “Follow Me” was invented for a concurrent eye-hand coordination task during truth-telling/lying. Undergraduate participants were instructed to tell truths on questions about undergraduate school whereas they were instructed to tell lies on interview questions about graduate school, pretending they were graduate students. Throughout the experiment, they operated the “Follow Me” software: moving the mouse pointer to follow a randomly-moving dot on a computer screen. The distance between the mouse pointer tip and the dot center was measured by the software every 50 ms. Frequency of distance fluctuation was analyzed as the index of cognitive effort consumed per second (i.e., “degree of cognitive effort”). The results revealed that the dominant frequency of distance fluctuation was significantly lower during encoding than during retrieving responses; and lower during lying than truth-telling. Thus, dominant frequency of distance fluctuation may be an effective index of cognitive effort. Moreover, both encoding and retrieving bald-faced lies were more cognitively effortful than truth-telling. This novel definition and measurement of degree of cognitive effort may contribute to the research field of deception as well as to many other fields in social cognition. PMID:25999903

  3. Rate of learning and asymptotic performance in an automatization task and the relation to reading.

    PubMed

    Hecht, Rozalia; Crewther, David; Crewther, Sheila

    2004-12-01

    In the present study, direct evidence was sought linking cognitive automatic processing with reading in the general adult population. Reading speed on single-task performance and dual-task performance were compared. A total of 18 adults without dyslexia participated (7 men and 11 women, age M=25.3 yr., SD=2.7). Participants initially were trained in single-task mode on two types of tasks. The first was a central alphanumeric equation task (true or false), which comprised 3 subtests of increasing difficulty, ranging from an easily automated task to a varied and unpredictable mathematical operation. The second task was a peripheral pattern subitization task for which stimulus exposure time was related to performance. Finally, participants received dual-task training, which required simultaneous processing of both tasks. Slower reading speed was significantly related to rate of learning and speed of performance on predictable alphanumeric operations in dual-task conditions. There was no effect of reading speed on performance in the varied alphanumeric task. Faster readers were no better than slower readers on the pattern-subitization task. These findings suggest that faster readers automatized the predictable alphanumeric task more rapidly than slower readers and hence were better able to cope with the dual-task condition.

  4. Effectiveness of a Forward Collision Warning System in simple and in dual task from an electrophysiological perspective.

    PubMed

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

    2013-04-29

    Forward Collision Warning Systems (FCWS) are expected to assist drivers; however, it is not completely clear whether these systems are of benefit to distracted drivers as much as they are to undistracted drivers. This study aims at investigating further the analysis of the effectiveness of a surrogate FCWS according to the attentional state of participants. In this experiment electrophysiological and behavioural data were recording while participants were required to drive in a simple car simulator and to react to the braking of the lead vehicle which could be announced by a warning system. The effectiveness of this warning system was evaluated when drivers were distracted or not by a secondary cognitive task. In a previous study, the warning signal was not completely effective likely due to the presence of another predictor of the forthcoming braking which competes with the warning. By eliminating this secondary predictor in the present study, the results confirmed the negative effect of the secondary task and revealed the expected effectiveness of the warning system at behavioural and electrophysiological levels.

  5. Influence of pharmacological manipulations of NMDA and cholinergic receptors on working versus reference memory in a dual component odor span task.

    PubMed

    MacQueen, David A; Dalrymple, Savannah R; Drobes, David J; Diamond, David M

    2016-06-01

    Developed as a tool to assess working memory capacity in rodents, the odor span task (OST) has significant potential to advance drug discovery in animal models of psychiatric disorders. Prior investigations indicate OST performance is impaired by systemic administration of N-methyl-d-aspartate receptor (NMDA-r) antagonists and is sensitive to cholinergic manipulations. The present study sought to determine whether an impairment in OST performance can be produced by systemic administration of the competitive NMDA-r antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP; 3, 10, 17 mg/kg i.p.) in a unique dual-component variant of the OST, and whether this impairment is ameliorated by nicotine (0.75 mg/kg i.p.). Male Sprague-Dawley rats were trained to asymptotic level of performance on a 24-trial two-comparison incrementing nonmatching to sample OST. In addition, rats were administered a two-comparison olfactory reference memory (RM) task, which was integrated into the OST. The RM task provided an assessment of the effects of drug administration on global behavioral measures, long-term memory and motivation. Several measures of working memory (span, longest run, and accuracy) were dose dependently impaired by CPP without adversely affecting RM. Analysis of drug effects across trial blocks demonstrated a significant impairment of performance even at low memory loads, suggesting a CPP-induced deficit of olfactory short-term memory that is not load-dependent. Although nicotine did not ameliorate CPP-induced impairments in span or accuracy, it did block the impairment in longest run produced by the 10 mg/kg dose of CPP. Overall, our results indicate that performance in our 24 odor two-comparison OST is capacity dependent and that CPP impaired OST working, but not reference, memory. PMID:27194794

  6. Orbital cortex neuronal responses during an odor-based conditioned associative task in rats.

    PubMed

    Yonemori, M; Nishijo, H; Uwano, T; Tamura, R; Furuta, I; Kawasaki, M; Takashima, Y; Ono, T

    2000-01-01

    Neuronal activity in the rat orbital cortex during discrimination of various odors [five volatile organic compounds (acetophenone, isoamyl acetate, cyclohexanone, p-cymene and 1,8-cineole), and food- and cosmetic-related odorants (black pepper, cheese, rose and perfume)] and other conditioned sensory stimuli (tones, light and air puff) was recorded and compared with behavioral responses to the same odors (black pepper, cheese, rose and perfume). In a neurophysiological study, the rats were trained to lick a spout that protruded close to its mouth to obtain sucrose or intracranial self-stimulation reward after presentation of conditioned stimuli. Of 150 orbital cortex neurons recorded during the task, 65 responded to one or more types of sensory stimuli. Of these, 73.8% (48/65) responded during presentation of an odor. Although the mean breadth of responsiveness (entropy) of the olfactory neurons based on the responses to five volatile organic compounds and air (control) was rather high (0.795), these stimuli were well discriminated in an odor space resulting from multidimensional scaling using Pearson's correlation coefficients between the stimuli. In a behavioral study, a rat was housed in an equilateral octagonal cage, with free access to food and choice among eight levers, four of which elicited only water (no odor, controls), and four of which elicited both water and one of four odors (black pepper, cheese, rose or perfume). Lever presses for each odor and control were counted. Distributions of these five stimuli (four odors and air) in an odor space derived from the multidimensional scaling using Pearson's correlation coefficients based on behavioral responses were very similar to those based on neuronal responses to the same five stimuli. Furthermore, Pearson's correlation coefficients between the same five stimuli based on the neuronal responses and those based on behavioral responses were significantly correlated. The results demonstrated a pivotal role of

  7. Relationships between Spontaneous Note-Taking, Self-Reported Strategies and Comprehension When Reading Multiple Texts in Different Task Conditions

    ERIC Educational Resources Information Center

    Hagen, Åste M.; Braasch, Jason L. G.; Bråten, Ivar

    2014-01-01

    This study investigated note-taking during multiple-text reading across two different task conditions in relation to comprehension performance and self-reports of strategy use. Forty-four undergraduates read multiple texts about climate change to write an argument or a summary. Analysis of students' spontaneous note-taking during reading…

  8. The use of uncertainty forecasts in complex decision tasks and various weather conditions.

    PubMed

    Joslyn, Susan L; Grounds, Margaret A

    2015-12-01

    Recent research on weather-related decision-making suggests that the inclusion of numeric uncertainty estimates in weather forecasts improves decision quality over single value forecasts or specific advice. However, it is unclear if the benefit of uncertainty estimates extends to more complex decision tasks, presumably requiring greater cognitive effort, or to tasks in which the decision is clear-cut, perhaps making the additional uncertainty information unnecessary. In the present research, participants completed a task in which they used single value weather forecasts, either alone, with freeze probabilities, advice, or both, to decide whether to apply salt to roads in winter to prevent icing or to withhold salt and risk a penalty. Participants completed either a simple binary choice version of the task or a complex version with 3 response options and accompanying rules for application. Some participants were shown forecasts near the freezing point, such that the need for salt was ambiguous, whereas other participants were shown forecasts well below the freezing point. Results suggest that participants with uncertainty estimates did better overall, and neither the task complexity nor the coldness of the forecasts reduced that advantage. However, unexpectedly colder forecasts lead to poorer decisions and an advantage for specific advice. PMID:26479974

  9. The use of uncertainty forecasts in complex decision tasks and various weather conditions.

    PubMed

    Joslyn, Susan L; Grounds, Margaret A

    2015-12-01

    Recent research on weather-related decision-making suggests that the inclusion of numeric uncertainty estimates in weather forecasts improves decision quality over single value forecasts or specific advice. However, it is unclear if the benefit of uncertainty estimates extends to more complex decision tasks, presumably requiring greater cognitive effort, or to tasks in which the decision is clear-cut, perhaps making the additional uncertainty information unnecessary. In the present research, participants completed a task in which they used single value weather forecasts, either alone, with freeze probabilities, advice, or both, to decide whether to apply salt to roads in winter to prevent icing or to withhold salt and risk a penalty. Participants completed either a simple binary choice version of the task or a complex version with 3 response options and accompanying rules for application. Some participants were shown forecasts near the freezing point, such that the need for salt was ambiguous, whereas other participants were shown forecasts well below the freezing point. Results suggest that participants with uncertainty estimates did better overall, and neither the task complexity nor the coldness of the forecasts reduced that advantage. However, unexpectedly colder forecasts lead to poorer decisions and an advantage for specific advice.

  10. A new technique for simulating composite material. Task 2: Analytical solutions with Generalized Impedance Boundary Conditions (GIBCs)

    NASA Technical Reports Server (NTRS)

    Ricoy, M. A.; Volakis, J. L.

    1989-01-01

    The diffraction problem associated with a multilayer material slab recessed in a perfectly conducting ground plane is formulated and solved via the Generalized Scattering Matrix Formulation (GSMF) in conjunction with the dual integral equation approach. The multilayer slab is replaced by a surface obeying a generalized impedance boundary condition (GIBC) to facilitate the computation of the pertinent Wiener Hopf split functions and their zeros. Both E(sub z) and H(sub z) polarizations are considered and a number of scattering patterns are presented, some of which are compared to exact results available for a homogeneous recessed slab.

  11. Effects of sleep deprivation on different phases of memory in the rat: dissociation between contextual and tone fear conditioning tasks

    PubMed Central

    Rossi, Vanessa Contatto; Tiba, Paula Ayako; Moreira, Karin Di Monteiro; Ferreira, Tatiana Lima; Oliveira, Maria Gabriela Menezes; Suchecki, Deborah

    2014-01-01

    Numerous studies show that sleep deprivation (SD) impacts negatively on cognitive processes, including learning and memory. Memory formation encompasses distinct phases of which acquisition, consolidation and retrieval are better known. Previous studies with pre-training SD induced by the platform method have shown impairment in fear conditioning tasks. Nonetheless, pre-training manipulations do not allow the distinction between effects on acquisition and/or consolidation, interfering, ultimately, on recall of/performance in the task. In the present study, animals were first trained in contextual and tone fear conditioning (TFC) tasks and then submitted to SD with the purpose to evaluate the effect of this manipulation on different stages of the learning process, e.g., in the uptake of (new) information during learning, its encoding and stabilization, and the recall of stored memories. Besides, we also investigated the effect of SD in the extinction of fear memory and a possible state-dependent learning induced by this manipulation. For each task (contextual or TFC), animals were trained and then distributed into control, not sleep-deprived (CTL) and SD groups, the latter being submitted to the modified multiple platform paradigm for 96 h. Subsets of eight rats in each group/experiment were submitted to the test of the tasks, either immediately or at different time intervals after SD. The results indicated that (a) pre- but not post-training SD impaired recall in the contextual and TFC; (b) this impairment was not state-dependent; and (c) in the contextual fear conditioning (CFC), pre-test SD prevented extinction of the learned task. Overall, these results suggest that SD interferes with acquisition, recall and extinction, but not necessarily with consolidation of emotional memory. PMID:25426040

  12. Embedding an identity-matching task within a prompting hierarchy to facilitate acquisition of conditional discriminations in children with autism.

    PubMed

    Fisher, Wayne W; Kodak, Tiffany; Moore, James W

    2007-01-01

    Least-to-most prompting hierarchies (e.g., progressing from verbal to modeled to physical prompts until the target response occurs) may be ineffective when the prompts do not cue the individual to attend to the relevant stimulus dimensions. In such cases, emission of the target response persistently requires one or more of the higher level prompts, a condition called prompt dependence (Clark & Green, 2004). Reinforcement of differential observing responses (DORs) has sometimes been used to ensure that participants attend to the relevant stimulus dimensions in matching-to-sample (MTS) tasks (e.g., Dube & McIlvane, 1999). For 2 participants with autism, we embedded an identity-matching task within a prompting hierarchy as a DOR to increase the likelihood that the participants attended to and discriminated the relevant features of the comparison stimuli in an MTS task. This procedure was compared with a traditional least-to-most prompting hierarchy and a no-reinforcement control condition in a multielement design. Results for both participants indicated that mastery-level acquisition of spoken-word-to-picture relations occurred only under the identity-matching condition. Findings are discussed relative to the use of DORs to facilitate acquisition of conditional discriminations in persons with autism or other conditions who do not attend to the comparison stimuli. PMID:17970262

  13. Active listening impairs visual perception and selectivity: an ERP study of auditory dual-task costs on visual attention.

    PubMed

    Gherri, Elena; Eimer, Martin

    2011-04-01

    The ability to drive safely is disrupted by cell phone conversations, and this has been attributed to a diversion of attention from the visual environment. We employed behavioral and ERP measures to study whether the attentive processing of spoken messages is, in itself, sufficient to produce visual-attentional deficits. Participants searched for visual targets defined by a unique feature (Experiment 1) or feature conjunction (Experiment 2), and simultaneously listened to narrated text passages that had to be recalled later (encoding condition), or heard backward-played speech sounds that could be ignored (control condition). Responses to targets were slower in the encoding condition, and ERPs revealed that the visual processing of search arrays and the attentional selection of target stimuli were less efficient in the encoding relative to the control condition. Results demonstrate that the attentional processing of visual information is impaired when concurrent spoken messages are encoded and maintained, in line with cross-modal links in selective attention, but inconsistent with the view that attentional resources are modality-specific. The distraction of visual attention by active listening could contribute to the adverse effects of cell phone use on driving performance. PMID:20465407

  14. The Roles of Private Speech and Inner Speech in Planning during Middle Childhood: Evidence from a Dual Task Paradigm

    ERIC Educational Resources Information Center

    Lidstone, Jane S. M.; Meins, Elizabeth; Fernyhough, Charles

    2010-01-01

    Children often talk themselves through their activities, producing private speech that is internalized to form inner speech. This study assessed the effect of articulatory suppression (which suppresses private and inner speech) on Tower of London performance in 7- to 10-year-olds, relative to performance in a control condition with a nonverbal…

  15. The effect of cueing therapy on single and dual-task gait in a drug naïve population of people with Parkinson's disease in northern Tanzania.

    PubMed

    Rochester, Lynn; Rafferty, Danny; Dotchin, Catherine; Msuya, Oliva; Minde, Victor; Walker, R W

    2010-05-15

    The incidence of Parkinson's disease (PD) in sub-Saharan Africa (SSA) is greater than thought however, is largely undiagnosed and untreated. This study aimed to evaluate a nonpharmacological approach using cueing therapy to improve gait in drug-naïve PD and the feasibility of delivering rehabilitation in northern Tanzania. In this study, twenty-one people with PD aged 76.4 years (12.9 SD) with varying disease severity participated. They received 9 x 30 min sessions of cueing therapy for gait problems over 3 weeks from a trained therapist delivered in their home environment. Cueing therapy consisted of walking in time to a metronome beat to correct step amplitude and step frequency during a range of functional activities. Gait was recorded on video before and after therapy, and videos were analyzed in the UK by an assessor not involved in data collection. Disease severity (UPDRS) and balance were also measured. Patients were assessed in their nearest clinic. Data were analyzed in Minitab and a P value of 0.05 was considered significant. Cueing therapy significantly improved single and dual task walking speed, step amplitude, and single task step frequency. There was also a significant improvement in motor impairment (UPDRS III) and activities of daily living (UPDRS II). The results provide promising evidence for the role of cueing therapy in PD for symptom management to reduce or delay medication onset. This study also supports the feasibility of rehabilitation in PD in community environments in SSA, which may be applicable to other developing regions.

  16. Comparing Three Dual-Task Methods and the Relationship to Physical and Cognitive Impairment in People with Multiple Sclerosis and Controls.

    PubMed

    Kirkland, Megan C; Wallack, Elizabeth M; Rancourt, Samantha N; Ploughman, Michelle

    2015-01-01

    Dual-tasking (DT) is a measure to detect impairments in people with multiple sclerosis (MS). We compared three DT methods to determine whether cognitive (Montreal Cognitive Assessment (MoCA)) or physical disability (Expanded Disease Severity Scale; EDSS) was related to DT performance. We recruited MS participants with low disability (<3 EDSS, n = 13) and high disability (≥3 EDSS, n = 9) and matched controls (n = 13). Participants walked at self-selected (SS) speed on an instrumented walkway (Protokinetics, Havertown, USA), followed by DT walks in randomized order: DT ABC (reciting every second letter of the alphabet), DT 7 (serially subtracting 7's from 100), and DT 3 (counting upwards, leaving out multiples and numbers that include 3). DT 7 resulted in the most consistent changes in performance. Both MS and control groups reduced velocity and cadence and shortened step length during DT with no significant differences between groups. Control subjects widened stride width by about 1 cm while MS subjects (collapsed as one group) did not. MS subjects with higher disability significantly increased percentage time in double support during DT compared to SS (F = 12.95, p < 0.001). The change in DS was related to cognitive and not physical disability (r = 0.54,  p < 0.05). PMID:26682069

  17. A dual-task design of corrosion-controlling and osteo-compatible hexamethylenediaminetetrakis- (methylene phosphonic acid) (HDTMPA) coating on magnesium for biodegradable bone implants application.

    PubMed

    Zhao, Sheng; Chen, Yingqi; Liu, Bo; Chen, Meiyun; Mao, Jinlong; He, Hairuo; Zhao, Yuancong; Huang, Nan; Wan, Guojiang

    2015-05-01

    Magnesium as well as its alloys appears increasingly as a revolutionary bio-metal for biodegradable implants application but the biggest challenges exist in its too fast bio-corrosion/degradation. Both corrosion-controllable and bio-compatible Mg-based bio-metal is highly desirable in clinic. In present work, hexamethylenediaminetetrakis (methylenephosphonic acid) [HDTMPA, (H2 O3 P-CH2 )2 -N-(CH2 )6 -N-(CH2 -PO3 H2 )2 ], as a natural and bioactive organic substance, was covalently immobilized and chelating-deposited onto Mg surface by means of chemical conversion process and dip-coating method, to fullfill dual-task performance of corrosion-protective and osteo-compatible functionalities. The chemical grafting of HDTMPA molecules, by participation of functional groups on pretreated Mg surface, ensured a firmly anchored base layer, and then sub-sequential chelating reactions of HDTMPA molecules guaranteed a homogenous and dense HDTMPA coating deposition on Mg substrate. Electrochemical corrosion and immersion degradation results reveal that the HDTMPA coated Mg provides a significantly better controlled bio-corrosion/degradation behavior in phosphate buffer saline solution as compared with untreated Mg from perspective of clinic requirement. Moreover, the HDTMPA coated Mg exhibits osteo-compatible in that it induces not only bioactivity of bone-like apatite precipitation but also promotes osteoblast cells adhesion and proliferation. Our well-controlled biodegradable and biocompatible HDTMPA modified Mg might bode well for next generation bone implant application.

  18. Unidirectional interference in use of nondominant hand during concurrent Grooved Pegboard and random number generation tasks.

    PubMed

    Strenge, Hans; Niederberger, Uwe

    2008-06-01

    The interference effect between Grooved Pegboard task with either hand and the executive task of cued verbal random number generation was investigated. 24 normal right-handed subjects performed each task under separate (single-task) and concurrent (dual-task) conditions. Articulatory suppression was required as an additional secondary task during pegboard performance. Analysis indicated an unambiguous distinction between the two hands. Comparisons of single-task and dual-task conditions showed an asymmetrical pattern of unidirectional interference with no practice effects during pegboard performance. Concurrent performance with nondominant hand but not the dominant hand of random number generation performance became continuously slower. There was no effect of divided attention on pegboard performance. Findings support the idea that the nondominant hand on the pegboard and random number tasks draw from the same processing resources but that for the executive aspect random number generation is more sensitive to changes in allocation of attentional resources. PMID:18712198

  19. Conditioned discrimination of magnetic inclination in a spatial-orientation arena task by homing pigeons (Columba livia).

    PubMed

    Mora, Cordula V; Acerbi, Merissa L; Bingman, Verner P

    2014-12-01

    It has been well established that homing pigeons are able to use the Earth's magnetic field to obtain directional information when returning to their loft and that their magnetic compass is based, at least in part, on the perception of magnetic inclination. Magnetic inclination has also been hypothesized in pigeons and other long-distance navigators, such as sea turtles, to play a role providing positional information as part of a map. Here we developed a behavioral paradigm which allows us to condition homing pigeons to discriminate magnetic inclination cues in a spatial-orientation arena task. Six homing pigeons were required to discriminate in a circular arena between feeders located either in a zone with a close to 0 deg inclination cue or in a zone with a rapidly changing inclination cue (-3 deg to +85 deg when approaching the feeder and +85 deg to -3 deg when moving away from the feeder) to obtain a food reward. The pigeons consistently performed this task above chance level. Control experiments, during which the coils were turned off or the current was running anti-parallel through the double-wound coil system, confirmed that no alternative cues were used by the birds in the discrimination task. The results show that homing pigeons can be conditioned to discriminate differences in magnetic field inclination, enabling investigation into the peripheral and central neural processing of geomagnetic inclination under controlled laboratory conditions. PMID:25278470

  20. Conditioned discrimination of magnetic inclination in a spatial-orientation arena task by homing pigeons (Columba livia).

    PubMed

    Mora, Cordula V; Acerbi, Merissa L; Bingman, Verner P

    2014-12-01

    It has been well established that homing pigeons are able to use the Earth's magnetic field to obtain directional information when returning to their loft and that their magnetic compass is based, at least in part, on the perception of magnetic inclination. Magnetic inclination has also been hypothesized in pigeons and other long-distance navigators, such as sea turtles, to play a role providing positional information as part of a map. Here we developed a behavioral paradigm which allows us to condition homing pigeons to discriminate magnetic inclination cues in a spatial-orientation arena task. Six homing pigeons were required to discriminate in a circular arena between feeders located either in a zone with a close to 0 deg inclination cue or in a zone with a rapidly changing inclination cue (-3 deg to +85 deg when approaching the feeder and +85 deg to -3 deg when moving away from the feeder) to obtain a food reward. The pigeons consistently performed this task above chance level. Control experiments, during which the coils were turned off or the current was running anti-parallel through the double-wound coil system, confirmed that no alternative cues were used by the birds in the discrimination task. The results show that homing pigeons can be conditioned to discriminate differences in magnetic field inclination, enabling investigation into the peripheral and central neural processing of geomagnetic inclination under controlled laboratory conditions.

  1. Effects of performing two visual tasks on single-trial detection of event-related potentials.

    PubMed

    Cecotti, Hubert; Eckstein, Miguel P; Giesbrecht, Barry

    2012-01-01

    The detection of event-related potentials (ERPs) in brain-computer interface (BCI) depends on the ability of the subject to pay attention to specific stimuli presented during the BCI task. For healthy users, a BCI shall be used as a complement to other existing devices, which involve the response to other tasks. Those tasks may impair selective attention, particularly if the stimuli have the same modality e.g. visual. It is therefore critical to analyze how single-trial detection of brain evoked response is impaired by the addition of tasks concerning the same modality. We tested 10 healthy participants using an application that has two visual target detection tasks. The first one corresponds to a rapid serial visual presentation paradigm where target detection is achieved by brain-evoked single-trial detection in the recorded electroencephalogram (EEG) signal. The second task is the detection of a visual event on a tactical map by a behavioral response. These tasks were tested individually (single task) and in parallel (dual-task). Whereas the performance of single-trial detection was not impaired between single and dual-task conditions, the behavioral performance decreased during the dual-task condition. These results quantify the performance drop that can occur in a dual-task system using both brain-evoked responses and behavioral responses. PMID:23366242

  2. Housing conditions and stimulus females: a robust social discrimination task for studying male rodent social recognition.

    PubMed

    Macbeth, Abbe H; Edds, Jennifer Stepp; Young, W Scott

    2009-01-01

    Social recognition (SR) enables rodents to distinguish between familiar and novel conspecifics, largely through individual odor cues. SR tasks utilize the tendency for a male to sniff and interact with a novel individual more than a familiar individual. Many paradigms have been used to study the roles of the neuropeptides oxytocin and vasopressin in SR. However, inconsistencies in results have arisen within similar mouse strains, and across different paradigms and laboratories, making reliable testing of SR difficult. The current protocol details a novel approach that is replicable across investigators and in different strains of mice. We created a protocol that uses gonadally intact, singly housed females presented within corrals to group-housed males. Housing females singly before testing is particularly important for reliable discrimination. This methodology will be useful for studying short-term social memory in rodents, and may also be applicable for longer term studies.

  3. Housing conditions and stimulus females: a robust social discrimination task for studying male rodent social recognition

    PubMed Central

    Macbeth, Abbe H.; Edds, Jennifer Stepp; Young, W. Scott

    2010-01-01

    Social recognition (SR) enables rodents to distinguish between familiar and novel conspecifics, largely through individual odor cues. SR tasks utilize the tendency for a male to sniff and interact with a novel individual more than a familiar individual. Many paradigms have been used to study the roles of the neuropeptides oxytocin and vasopressin in SR. However, inconsistencies in results have arisen within similar mouse strains, and across different paradigms and laboratories, making reliable testing of social recognition difficult. The current protocol details a novel approach that is replicable across investigators and in different strains of mice. We created a protocol that utilizes gonadally intact, singly housed females presented within corrals to group-housed males. Housing females singly prior to testing is particularly important for reliable discrimination. This methodology will be useful for studying short-term social memory in rodents, and may also be applicable for longer-term studies. PMID:19816420

  4. The dual effect of CA1 NMDA receptor modulation on ACPA-induced amnesia in step-down passive avoidance learning task.

    PubMed

    Nasehi, Mohammad; Amin-Yavari, Samaneh; Ebrahimi-Ghiri, Mohaddeseh; Torabi-Nami, Mohammad; Zarrindast, Mohammad-Reza

    2015-04-01

    It is well documented that cannabinoids play an important role in certain hippocampal memory processes in rodents. On the other hand, N-Methyl-d-aspartate receptors (NMDARs) mediate the synaptic plasticity related to learning and memory processes which take place in the hippocampus. Such insights prompted us to investigate the influence of dorsal hippocampal (CA1) NMDA receptor agents on amnesia induced by cannabinoid CB1 receptor agonist, arachidonylcyclopropylamide (ACPA) in male mice. One-trial step-down passive avoidance and hole-board apparatuses were used to examine the memory retrieval and exploratory behaviors, respectively. Based on our findings, pre-training intraperitoneal (i.p.) administration of ACPA (0.01mg/kg) decreased memory acquisition. Moreover, pre-training intra-CA1 infusion of NMDA (0.001, 0.0125, 0.025 and 0.2µg/mouse), d-AP7 (0.5 and 1µg/mouse) or AM251 (50ng/mouse) impaired the memory acquisition. Meanwhile, NMDA-treated animals at the doses of 0.0005, 0.05 and 0.1µg/mouse acquired memory formation. In addition, intra-CA1 microinjection of NMDA (0.0005) plus different doses of ACPA potentiated the ACPA response, while NMDA (0.1) plus the lower or the higher dose of ACPA potentiated or restored the ACPA response, respectively. Further investigation revealed that a subthreshold dose of d-AP7 could potentiate the memory acquisition impairment induced by ACPA. Moreover, the subthreshold dose of AM251 did not alter the ACPA response, while the effective dose of the drug restored the memory acquisition impairment induced by ACPA. According to these results, we concluded that activation of the NMDA receptors in the CA1 mediates a dual effect on ACPA-induced amnesia in step-down passive avoidance learning task.

  5. Brain c-Fos immunocytochemistry and cytochrome oxidase histochemistry after a fear conditioning task.

    PubMed

    Conejo, Nélida M; González Pardo, Héctor; López, Matías; Cantora, Raúl; Arias, Jorge L

    2007-05-01

    The involvement of the basolateral and the medial amygdala in fear conditioning was evaluated using different markers of neuronal activation. The method described here is a combination of cytochrome oxidase (CO) histochemistry and c-Fos immunocytochemistry on fresh frozen brain sections. Freezing behavior was used as an index of auditory and contextual fear conditioning. As expected, freezing scores were significantly higher in rats exposed to tone-shock pairings in a distinctive environment (conditioned; COND), as compared to rats that did not receive any shocks (UNCD). CO labeling was increased in the basolateral and medial amygdala of the COND group. Conversely, c-Fos expression in the basolateral and medial amygdala was lower in the COND group as compared to the UNCD group. Furthermore, c-Fos expression was particularly high in the medial amygdala of the UNCD group. The data provided by both techniques indicate that these amygdalar nuclei could play different roles on auditory and contextual fear conditioning. PMID:17425902

  6. Evaluation of Wall Boundary Conditions for Impedance Eduction Using a Dual-Source Method

    NASA Technical Reports Server (NTRS)

    Watson, W. R.; Jones, M. G.

    2012-01-01

    The accuracy of the Ingard-Myers boundary condition and a recently proposed modified Ingard-Myers boundary condition is evaluated for use in impedance eduction under the assumption of uniform mean flow. The evaluation is performed at three centerline Mach numbers, using data acquired in a grazing flow impedance tube, using both upstream and downstream propagating sound sources, and on a database of test liners for which the expected behavior of the impedance spectra is known. The test liners are a hard-wall insert consisting of 12.6 mm thick aluminum, a linear liner without a facesheet consisting of a number of small diameter but long cylindrical channels embedded in a ceramic material, and two conventional nonlinear liners consisting of a perforated facesheet bonded to a honeycomb core. The study is restricted to a frequency range for which only plane waves are cut on in the hard-wall sections of the flow impedance tube. The metrics used to evaluate each boundary condition are 1) how well it educes the same impedance for upstream and downstream propagating sources, and 2) how well it predicts the expected behavior of the impedance spectra over the Mach number range. The primary conclusions of the study are that the same impedance is educed for upstream and downstream propagating sources except at the highest Mach number, that an effective impedance based on both the upstream and downstream measurements is more accurate than an impedance based on the upstream or downstream data alone, and that the Ingard-Myers boundary condition with an effective impedance produces results similar to that achieved with the modified Ingard-Myers boundary condition.

  7. Conditional Discriminations by Preverbal Children in an Identity Matching-to-Sample Task

    ERIC Educational Resources Information Center

    de Alcantara Gil, Maria Stella C.; de Oliveira, Thais Porlan; McIlvane, William J.

    2011-01-01

    This study sought to develop methodology for assessing whether children ages 16-21 months could learn to match stimuli on the basis of physical identity in conditional discrimination procedures routinely used in stimulus equivalence research with older participants. The study was conducted in a private room at a day-care center for children and…

  8. Sensitivity and Bias under Conditions of Equal and Unequal Academic Task Difficulty

    ERIC Educational Resources Information Center

    Reed, Derek D.; Martens, Brian K.

    2008-01-01

    We conducted an experimental analysis of children's relative problem-completion rates across two workstations under conditions of equal (Experiment 1) and unequal (Experiment 2) problem difficulty. Results were described using the generalized matching equation and were evaluated for degree of schedule versus stimulus control. Experiment 1 involved…

  9. Dual role of dopamine D(2)-like receptors in the mediation of conditioned and unconditioned fear.

    PubMed

    Brandão, Marcus Lira; de Oliveira, Amanda Ribeiro; Muthuraju, Sangu; Colombo, Ana Caroline; Saito, Viviane Mitsuko; Talbot, Teddy

    2015-11-14

    A reduction of dopamine release or D2 receptor blockade in the terminal fields of the mesolimbic system, particularly the amygdala, clearly reduces conditioned fear. Similar D2 receptor antagonism in the neural substrates of fear in the midbrain tectum attenuates the processing of unconditioned aversive information. However, the implications of the interplay between opposing actions of dopamine in the rostral and caudal segments of the dopaminergic system are still unclear. Previous studies from this laboratory have reported the effects of dopaminergic drugs on behavior in rats in the elevated plus maze, auditory-evoked potentials (AEPs) recorded from the midbrain tectum, fear-potentiated startle, and conditioned freezing. These findings led to an interesting framework on the functional roles of dopamine in both anxiety and fear states. Dopamine D2 receptor inhibition in the terminal fields of the mesolimbic dopamine system generally causes anxiolytic-like effects, whereas the activity of midbrain substrates of unconditioned fear are enhanced by D2 receptor antagonists, suggesting that D2 receptor-mediated mechanisms play opposing roles in fear/anxiety processes, depending on the brain region under study. Dopamine appears to mediate conditioned fear by acting at rostral levels of the brain and regulate unconditioned fear at the midbrain level, likely by reducing the sensorimotor gating of aversive events.

  10. Event-related desynchronization/synchronization during discrimination task conditions in patients with Parkinson's disease.

    PubMed

    Dushanova, Juliana; Philipova, Dolja; Nikolova, Gloria

    2009-09-01

    Parkinson's disease is a neurodegenerative disorder with symptoms, which include movement disturbances and changes of cognitive information processing. The aim of the present study was to investigate the functional relationships between oscillatory electroencephalographic (EEG) dominant components with event-related desynchronization/synchronization (ERD/ERS) method for idiopathic non-demented Parkinson's patients (PP) and control subjects (CS) during auditory discrimination tasks within two post-stimulus intervals of 0-250 and 250-600 ms. When comparing the CS and PP during the first post-stimulus period, we found delta- and theta-ERS significantly pronounced in CS for both tone types (low--800, high--1,000 Hz) with the following exceptions: at Fz, PP displayed higher delta-ERS, while at C3' theta-ERD in response to a high tone. Alpha-ERS was found in PP in response to either tone at all electrodes and mainly alpha-ERD in CS. In the second post-stimulus interval, the significant differences between the groups were: (i) delta-ERS in CS and delta-ERD in PP in response to the low tone and (ii) delta-ERS for both groups in answer to the high tone, more prominent in CS at Cz and Pz, except for delta-ERD in PP at C3'. For both groups, we detected predominantly theta-ERD and alpha-ERD following both tone types within this second interval. PP showed more expressed theta-ERD at Fz and parietal theta-ERS. Alpha-ERD was significantly higher in CS, while frontal alpha-ERD was more prominent in the PP in response to both tones. The data obtained showed specific functional differences of event-related oscillatory activity in cognitive and sensory-motor information processing between the PP and CS. PMID:19291392

  11. Postural Control Can Be Well Maintained by Healthy, Young Adults in Difficult Visual Task, Even in Sway-Referenced Dynamic Conditions

    PubMed Central

    Lions, Cynthia; Bucci, Maria Pia; Bonnet, Cédrick

    2016-01-01

    Purpose To challenge the validity of existing cognitive models of postural control, we recorded eye movements and postural sway during two visual tasks (a control free-viewing task and a difficult searching task), and two postural tasks (one static task in which the platform was maintained stable and a dynamic task in which the platform moved in a sway-referenced manner.) We expected these models to be insufficient to predict the results in postural control both in static–as already shown in the literature reports–and in dynamic platform conditions. Methods Twelve healthy, young adults (17.3 to 34.1 years old) participated in this study. Postural performances were evaluated using the Multitest platform (Framiral®) and ocular recording was performed with Mobile T2 (e(ye)BRAIN®). In the free-viewing task, the participants had to look at an image, without any specific instruction. In the searching task, the participants had to look at an image and also to locate the position of an object in the scene. Results Postural sway was only significantly higher in the dynamic free-viewing condition than in the three other conditions with no significant difference between these three other conditions. Visual task performance was slightly higher in dynamic than in static conditions. Discussion As expected, our results did not confirm the main assumption of the current cognitive models of postural control–i.e. that the limited attentional resources of the brain should explain changes in postural control in our conditions. Indeed, 1) the participants did not sway significantly more in the sway-referenced dynamic searching condition than in any other condition; 2) the participants swayed significantly less in both static and dynamic searching conditions than in the dynamic free-viewing condition. We suggest that a new cognitive model illustrating the adaptive, functional role of the brain to control upright stance is necessary for future studies. PMID:27736934

  12. Repairable-conditionally repairable damage model based on dual Poisson processes.

    PubMed

    Lind, B K; Persson, L M; Edgren, M R; Hedlöf, I; Brahme, A

    2003-09-01

    The advent of intensity-modulated radiation therapy makes it increasingly important to model the response accurately when large volumes of normal tissues are irradiated by controlled graded dose distributions aimed at maximizing tumor cure and minimizing normal tissue toxicity. The cell survival model proposed here is very useful and flexible for accurate description of the response of healthy tissues as well as tumors in classical and truly radiobiologically optimized radiation therapy. The repairable-conditionally repairable (RCR) model distinguishes between two different types of damage, namely the potentially repairable, which may also be lethal, i.e. if unrepaired or misrepaired, and the conditionally repairable, which may be repaired or may lead to apoptosis if it has not been repaired correctly. When potentially repairable damage is being repaired, for example by nonhomologous end joining, conditionally repairable damage may require in addition a high-fidelity correction by homologous repair. The induction of both types of damage is assumed to be described by Poisson statistics. The resultant cell survival expression has the unique ability to fit most experimental data well at low doses (the initial hypersensitive range), intermediate doses (on the shoulder of the survival curve), and high doses (on the quasi-exponential region of the survival curve). The complete Poisson expression can be approximated well by a simple bi-exponential cell survival expression, S(D) = e(-aD) + bDe(-cD), where the first term describes the survival of undamaged cells and the last term represents survival after complete repair of sublethal damage. The bi-exponential expression makes it easy to derive D(0), D(q), n and alpha, beta values to facilitate comparison with classical cell survival models.

  13. Dual vulnerability of TDP-43 to calpain and caspase-3 proteolysis after neurotoxic conditions and traumatic brain injury

    PubMed Central

    Yang, Zhihui; Lin, Fan; Robertson, Claudia S; Wang, Kevin K W

    2014-01-01

    Transactivation response DNA-binding protein 43 (TDP-43) proteinopathy has recently been reported in chronic traumatic encephalopathy, a neurodegenerative condition linked to prior history of traumatic brain injury (TBI). While TDP-43 appears to be vulnerable to proteolytic modifications under neurodegenerative conditions, the mechanism underlying the contribution of TDP-43 to the pathogenesis of TBI remains unknown. In this study, we first mapped out the calpain or caspase-3 TDP-43 fragmentation patterns by in vitro protease digestion. Concurrently, in cultured cerebrocortical neurons subjected to cell death challenges, we identified distinct TDP-43 breakdown products (BDPs) of 35, 33, and 12 kDa that were indicative of dual calpain/caspase attack. Cerebrocortical culture incubated with calpain and caspase-fragmented TDP-43 resulted in neuronal injury. Furthermore, increased TDP-43 BDPs as well as redistributed TDP-43 from the nucleus to the cytoplasm were observed in the mouse cortex in two TBI models: controlled cortical impact injury and overpressure blast-wave-induced brain injury. Finally, TDP-43 and its 35 kDa fragment levels were also elevated in the cerebrospinal fluid (CSF) of severe TBI patients. This is the first evidence that TDP-43 might be involved in acute neuroinjury and TBI pathology, and that TDP-43 and its fragments may have biomarker utilities in TBI patients. PMID:24917042

  14. Dual Mechanism Conceptual Model for Cr Isotope Fractionation during Reduction by Zerovalent Iron under Saturated Flow Conditions.

    PubMed

    Jamieson-Hanes, Julia H; Amos, Richard T; Blowes, David W; Ptacek, Carol J

    2015-05-01

    Chromium isotope analysis is rapidly becoming a valuable complementary tool for tracking Cr(VI) treatment in groundwater. Evaluation of various treatment materials has demonstrated that the degree of isotope fractionation is a function of the reaction mechanism, where reduction of Cr(VI) to Cr(III) induces the largest fractionation. However, it has also been observed that uniform flow conditions can contribute complexity to isotope measurements. Here, laboratory batch and column experiments were conducted to assess Cr isotope fractionation during Cr(VI) reduction by zerovalent iron under both static and saturated flow conditions. Isotope measurements were accompanied by traditional aqueous geochemical measurements (pH, Eh, concentrations) and solid-phase analysis by scanning electron microscopy and X-ray absorption spectroscopy. Increasing δ(53)Cr values were associated with decreasing Cr(VI) concentrations, which indicates reduction; solid-phase analysis showed an accumulation of Cr(III) on the iron. Reactive transport modeling implemented a dual mechanism approach to simulate the fractionation observed in the experiments. The faster heterogeneous reaction pathway was associated with minimal fractionation (ε=-0.2‰), while the slower homogeneous pathway exhibited a greater degree of fractionation (ε=-0.9‰ for the batch experiment, and ε=-1.5‰ for the column experiment). PMID:25839086

  15. Role of Muscarinic Acetylcholine Receptors in Serial Feature-Positive Discrimination Task during Eyeblink Conditioning in Mice.

    PubMed

    Rahman, Md Ashrafur; Tanaka, Norifumi; Usui, Koji; Kawahara, Shigenori

    2016-01-01

    We investigated the role of muscarinic acetylcholine receptors (mAChRs) in eyeblink serial feature-positive discrimination learning in mice using the mAChR antagonist. A 2-s light cue was delivered 5 or 6 s before the presentation of a 350-ms tone paired with a 100-ms periorbital electrical shock (cued trial) but not before the tone-alone presentation (non-cued trial). Mice received 30 cued and 30 non-cued trials each day in a random order. We found that saline-injected control mice were successfully discriminating between cued and non-cued trials within a few days of conditioning. The mice responded more frequently to the tone in cued trials than in non-cued trials. Analysis of conditioned response (CR) dynamics revealed that the CR onset latency was shorter in cued trials than in non-cued trials, despite the CR peak amplitude not differing significantly between the two conditions. In contrast, scopolamine-injected mice developed an equal number of CRs with similar temporal patterns irrespective of the presence of the cue during the 7 days of conditioning, indicating in a failure to acquire conditional discrimination. In addition, the scopolamine administration to the control mice after they had successfully acquired discrimination did not impair the conditional discrimination and expression of pre-acquired CR. These results suggest that mAChRs may play a pivotal role in memory formation in the conditional brain state associated with the feature cue; however they are unlikely to be involved in the development of discrimination after conditional memory had formed in the serial feature-positive discrimination task during eyeblink conditioning. PMID:26808980

  16. Role of Muscarinic Acetylcholine Receptors in Serial Feature-Positive Discrimination Task during Eyeblink Conditioning in Mice

    PubMed Central

    Rahman, Md. Ashrafur; Tanaka, Norifumi; Usui, Koji; Kawahara, Shigenori

    2016-01-01

    We investigated the role of muscarinic acetylcholine receptors (mAChRs) in eyeblink serial feature-positive discrimination learning in mice using the mAChR antagonist. A 2-s light cue was delivered 5 or 6 s before the presentation of a 350-ms tone paired with a 100-ms periorbital electrical shock (cued trial) but not before the tone-alone presentation (non-cued trial). Mice received 30 cued and 30 non-cued trials each day in a random order. We found that saline-injected control mice were successfully discriminating between cued and non-cued trials within a few days of conditioning. The mice responded more frequently to the tone in cued trials than in non-cued trials. Analysis of conditioned response (CR) dynamics revealed that the CR onset latency was shorter in cued trials than in non-cued trials, despite the CR peak amplitude not differing significantly between the two conditions. In contrast, scopolamine-injected mice developed an equal number of CRs with similar temporal patterns irrespective of the presence of the cue during the 7 days of conditioning, indicating in a failure to acquire conditional discrimination. In addition, the scopolamine administration to the control mice after they had successfully acquired discrimination did not impair the conditional discrimination and expression of pre-acquired CR. These results suggest that mAChRs may play a pivotal role in memory formation in the conditional brain state associated with the feature cue; however they are unlikely to be involved in the development of discrimination after conditional memory had formed in the serial feature-positive discrimination task during eyeblink conditioning. PMID:26808980

  17. Aged neuronal nitric oxide knockout mice show preserved olfactory learning in both social recognition and odor-conditioning tasks.

    PubMed

    James, Bronwen M; Li, Qin; Luo, Lizhu; Kendrick, Keith M

    2015-01-01

    There is evidence for both neurotoxic and neuroprotective roles of nitric oxide (NO) in the brain and changes in the expression of the neuronal isoform of NO synthase (nNOS) gene occur during aging. The current studies have investigated potential support for either a neurotoxic or neuroprotective role of NO derived from nNOS in the context of aging by comparing olfactory learning and locomotor function in young compared to old nNOS knockout (nNOS(-/-)) and wildtype control mice. Tasks involving social recognition and olfactory conditioning paradigms showed that old nNOS(-/-) animals had improved retention of learning compared to similar aged wildtype controls. Young nNOS(-/-) animals showed superior reversal learning to wildtypes in a conditioned learning task, although their performance was weakened with age. Interestingly, whereas young nNOS(-/-) animals were impaired in long term memory for social odors compared to wildtype controls, in old animals this pattern was reversed, possibly indicating beneficial compensatory changes influencing olfactory memory may occur during aging in nNOS(-/-) animals. Possibly such compensatory changes may have involved increased NO from other NOS isoforms since the memory deficit in young nNOS(-/-) animals could be rescued by the NO-donor, molsidomine. Both nNOS(-/-) and wildtype animals showed an age-associated decline in locomotor activity although young nNOS(-/-) animals were significantly more active than wildtypes, possibly due to an increased interest in novelty. Overall our findings suggest that lack of NO release via nNOS may protect animals to some extent against age-associated cognitive decline in memory tasks typically involving olfactory and hippocampal regions, but not against declines in reversal learning or locomotor activity.

  18. Task switching and response correspondence in the psychological refractory period paradigm

    NASA Technical Reports Server (NTRS)

    Lien, Mei-Ching; Schweickert, Richard; Proctor, Robert W.

    2003-01-01

    Three experiments examined the effects of task switching and response correspondence in a psychological refractory period paradigm. A letter task (vowel-consonant) and a digit task (odd-even) were combined to form 4 possible dual-task pairs in each trial: letter-letter, letter-digit, digit-digit, and digit-letter. Foreknowledge of task transition (repeat or switch) and task identity (letter or digit) was varied across experiments: no foreknowledge in Experiment 1, partial foreknowledge (task transition only) in Experiment 2, and full foreknowledge in Experiment 3. For all experiments, the switch cost for Task 2 was additive with stimulus onset asynchrony, and the response-correspondence effect for Task 2 was numerically smaller in the switch condition than in the repeat condition. These outcomes suggest that reconfiguration for Task 2 takes place after the central processing of Task 1 and that the crosstalk correspondence effect is due to response activation by way of stimulus-response associations.

  19. The dual function of nitrite under stomach conditions is modulated by reducing compounds.

    PubMed

    Volk, J; Gorelik, S; Granit, R; Kohen, R; Kanner, J

    2009-09-01

    Salivary nitrite plays a role in the lipid peroxidation process of muscle tissue in simulated gastric fluid. The objectives of our study were to elucidate the fate of nitrite in the presence of reducing compounds and to evaluate its effect on lipid peroxidation during digestion. Nitrite at pH 3 (possibly NO(2.), not NO.) can oxidize beta-carotene, but the addition of reducing compounds, ascorbic acid or polyphenols, alters its effect. Ascorbic acid alone promoted the formation of NO. from nitrite only up to pH 3, but the addition of iron ions facilitated the formation of NO. up to pH 5.5. NO prevented membranal lipid peroxidation under stomach conditions. Nitrite, only in the presence of reducing compounds, achieved the same goal but at much higher concentrations. Addition of polyphenols to nitrite synergistically improved its antioxidant effect. Therefore, to promote NO. production and to achieve better control of the lipid peroxidation process in the stomach, a nitrite-rich meal should be consumed simultaneously with food rich in polyphenols. PMID:19375499

  20. The dual function of nitrite under stomach conditions is modulated by reducing compounds.

    PubMed

    Volk, J; Gorelik, S; Granit, R; Kohen, R; Kanner, J

    2009-09-01

    Salivary nitrite plays a role in the lipid peroxidation process of muscle tissue in simulated gastric fluid. The objectives of our study were to elucidate the fate of nitrite in the presence of reducing compounds and to evaluate its effect on lipid peroxidation during digestion. Nitrite at pH 3 (possibly NO(2.), not NO.) can oxidize beta-carotene, but the addition of reducing compounds, ascorbic acid or polyphenols, alters its effect. Ascorbic acid alone promoted the formation of NO. from nitrite only up to pH 3, but the addition of iron ions facilitated the formation of NO. up to pH 5.5. NO prevented membranal lipid peroxidation under stomach conditions. Nitrite, only in the presence of reducing compounds, achieved the same goal but at much higher concentrations. Addition of polyphenols to nitrite synergistically improved its antioxidant effect. Therefore, to promote NO. production and to achieve better control of the lipid peroxidation process in the stomach, a nitrite-rich meal should be consumed simultaneously with food rich in polyphenols.

  1. The boundary conditions of priming of visual search: from passive viewing through task-relevant working memory load.

    PubMed

    Kristjánsson, Arni; Saevarsson, Styrmir; Driver, Jon

    2013-06-01

    Priming of visual search has a dominating effect upon attentional shifts and is thought to play a decisive role in visual stability. Despite this importance, the nature of the memory underlying priming remains controversial. To understand more fully the necessary conditions for priming, we contrasted passive versus active viewing of visual search arrays. There was no priming from passive viewing of search arrays, while it was strong for active search of the same displays. Displays requiring no search resulted in no priming, again showing that search is needed for priming to occur. Finally, we introduced working memory load during visual search in an effort to disrupt priming. The memorized items had either the same colors as or different colors from the visual search items. Retaining items in working memory inhibited priming of the working memory task-relevant colors, while little interference was observed for unrelated colors. The picture that emerges of priming is that it requires active attentional processing of the search items in addition to the operation of visual working memory, where the task relevance of the working memory load plays a key role.

  2. The Effects of Physical Context Changes and Multiple Extinction Contexts on Two Forms of Renewal in a Conditioned Suppression Task with Humans

    ERIC Educational Resources Information Center

    Neumann, David L.

    2006-01-01

    Three experiments examined the effects of physical context changes and multiple extinction contexts on the renewal of conditioned suppression in humans. A conditioned suppression task used an undesirable event as the unconditional stimulus (US). One conditional stimulus (CS+) predicted the occurrence of the US and another (CS-) predicted US…

  3. The importance of the context in the hippocampus and brain related areas throughout the performance of a fear conditioning task.

    PubMed

    Arias, Natalia; Méndez, Marta; Arias, Jorge L

    2015-11-01

    The importance context has been broadly studied in the management of phobias and in the drug addiction literature. The way in which changes to a context influence behavior after the simple acquisition of a passive avoidance task remains unclear. The hippocampus has long been implicated in the contextual and spatial processing required for contextual fear, but its role in encoding the aversive component of a contextual fear memory is still inconclusive. Our work tries to elucidate whether a change in context, represented as differences in the load of the stimuli, is critical for learning about the context-shock association and whether this manipulation of the context could be linked to any change in metabolic brain activity requirements. For this purpose, we used an avoidance conditioning task. Animals were divided into three different experimental conditions. In one group, acquisition was performed in an enriched stimuli environment and retention was performed in a typically lit chamber (the PA-ACQ-CONTX group). In another group, acquisition was performed in the typically lit chamber and retention was undertaken in the highly enriched chamber (the PA-RET-CONTX group). Finally, for the control group, PA-CN-CONTX, acquisition, and retention were performed in the enriched stimuli environment. Our results showed that the PA-ACQ-CONTX group had longer escape latencies and poorer retention than the PA-RET-CONTX and PA-CN-CONTX groups after 24 h of acquisition under contextual changes. To study metabolic brain activity, histochemical labelling of cytochrome c-oxidase (CO) was performed. CO results suggested a neural circuit including the hippocampus, amygdala, thalamus, parahippocampal cortices, and mammillary nuclei that is involved in the learning and memory processes that enable context-dependent behavior. These results highlight how dysfunction in this network may be involved in the contextualization of fear associations that underlie several forms of psychopathology

  4. Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

    PubMed Central

    Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

    2014-01-01

    Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

  5. Application of Discrete Event Control to the Insertion Task of Electric Line Using 6-Link Electro-Hydraulic Manipulators with Dual Arm

    NASA Astrophysics Data System (ADS)

    Ahn, Kyoungkwan; Yokota, Shinichi

    Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. The maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system using electro-hydraulic manipulator because hydraulic manipulators have the advantage of electric insulation. Meanwhile it is relatively difficult to realize autonomous assembly tasks particularly in the case of manipulating flexible objects such as electric lines. In this report, a discrete event control system is introduced for automatic assembly task of electric lines into sleeves as one of a typical task of active electric power lines. In the implementation of a discrete event control system, LVQNN (learning vector quantization neural network) is applied to the insertion task of electric lines to sleeves. In order to apply these proposed control system to the unknown environment, virtual learning data for LVQNN was generated by fuzzy inference. By the experimental results of two types of electric lines and sleeves, these proposed discrete event control and neural network learning algorithm are confirmed very effective to the insertion tasks of electric lines to sleeves as a typical task of active electric power maintenance tasks.

  6. A Functional Near-Infrared Spectroscopy Study of Lexical Decision Task Supports the Dual Route Model and the Phonological Deficit Theory of Dyslexia

    ERIC Educational Resources Information Center

    Sela, Itamar; Izzetoglu, Meltem; Izzetoglu, Kurtulus; Onaral, Banu

    2014-01-01

    The dual route model (DRM) of reading suggests two routes of reading development: the phonological and the orthographic routes. It was proposed that although the two routes are active in the process of reading; the first is more involved at the initial stages of reading acquisition, whereas the latter needs more reading training to mature. A…

  7. CS-dependent response probability in an auditory masked-detection task: considerations based on models of Pavlovian conditioning.

    PubMed

    Mason, Christine R; Idrobo, Fabio; Early, Susan J; Abibi, Ayome; Zheng, Ling; Harrison, J Michael; Carney, Laurel H

    2003-05-01

    Experimental studies were performed using a Pavlovian-conditioned eyeblink response to measure detection of a variable-sound-level tone (T) in a fixed-sound-level masking noise (N) in rabbits. Results showed an increase in the asymptotic probability of conditioned responses (CRs) to the reinforced TN trials and a decrease in the asymptotic rate of eyeblink responses to the non-reinforced N presentations as a function of the sound level of the T. These observations are consistent with expected behaviour in an auditory masked detection task, but they are not consistent with predictions from a traditional application of the Rescorla-Wagner or Pearce models of associative learning. To implement these models, one typically considers only the actual stimuli and reinforcement on each trial. We found that by considering perceptual interactions and concepts from signal detection theory, these models could predict the CS dependence on the sound level of the T. In these alternative implementations, the animals response probabilities were used as a guide in making assumptions about the "effective stimuli".

  8. Effects of a secondary task on obstacle avoidance in healthy young adults.

    PubMed

    Siu, Ka-Chun; Catena, Robert D; Chou, Li-Shan; van Donkelaar, Paul; Woollacott, Marjorie H

    2008-01-01

    Research on attention and gait stability has suggested that the process of recovering gait stability requires attentional resources, but the effect of performing a secondary task on stability during obstacle avoidance is poorly understood. Using a dual-task paradigm, the present experiment investigated the extent to which young adults are able to respond to a secondary auditory Stroop task (requiring executive attentional network resources) concurrently with obstacle crossing during gait when compared with performing unobstructed walking or sitting (control task). Our results demonstrated that as the level of difficulty in the postural task increased, there was a significant reduction in verbal response time from congruent to incongruent conditions in the auditory Stroop task, but no differences in gait parameters, indicating that these postural tasks require attention, and that young adults use a strategy of modulating the auditory Stroop task performance while keeping stable gait performance under the dual-task situations. Our findings suggest the existence of a hierarchy of control within both postural task (obstacle avoidance requires the most information processing resources) and dual-task (with gait stability being a priority) conditions. PMID:17717655

  9. Is word perception in a second language more vulnerable than in one's native language? Evidence from brain potentials in a dual task setting.

    PubMed

    Hohlfeld, Annette; Mierke, Karsten; Sommer, Werner

    2004-06-01

    We assessed the effect of additional tasks on language perception in second-language and native speakers. The N400 component of the event-related potential was recorded to spoken nouns that had to be judged for synonymity with a preceding word, while additional choice responses were required to visual stimuli. In both participant groups N400 was delayed as a function of temporal overlap with the additional task. In second-language speakers there was a global delay of N400 independent of additional task load and a decrease of accuracy at highest overlap. These findings are interpreted within a single channel account of language perception.

  10. A dual-temperature-difference approach to estimate daytime sensible and latent heat fluxes under advective conditions during BEAREX08

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Dual-Temperature-Difference (DTD) approach uses continuous radiometric surface temperature measurements in a two-source (soil + vegetation) energy balance model to solve for the daytime evolution of the sensible and latent heat fluxes. By using the surface-air temperature difference at two time...

  11. Menopausal hormone therapy for the primary prevention of chronic conditions. U.S. Preventive Services Task Force recommendation statement.

    PubMed

    Kreatsoulas, Catherine; Anand, Sonia S

    2013-01-01

    Since the early 20th century, scientists have been tantalized with the hypothesis that premenopausal health benefits in women can be preserved in postmenopausal women with the supplementation of exogenous hormone replacement therapy (HRT) of estrogen (alone/with progesterone). This hypothesis was shattered when the results of 2 large randomized controlled trials (RCTs), the Heart Estrogen/Progesterone Replacement Study (HERS) and Women's Health Initiative (WHI), reported an increased risk of adverse clinical outcomes including coronary heart disease, thromboembolic events, stroke, dementia, urinary incontinence, gallbladder disease, and breast cancer. However, since the WHI was published, firestorms of critique, controversy, and multiple subgroup analyses have populated the medical literature, predominantly focused around the analysis of the age of women at entry into the trials (hypothesized as an effect modifier) and suggesting lower-dose preparations including using bioidentical hormones. Recently, the U.S. Preventive Services Task Force (USPSTF) along with other professional groups have issued recommendations against the use of HRT to prevent chronic conditions. In this review, we review the most recent evidence, including the long-term follow-up data from RCTs along a multitude of health outcomes.

  12. The Personality Trait of Intolerance to Uncertainty Affects Behavior in a Novel Computer-Based Conditioned Place Preference Task.

    PubMed

    Radell, Milen L; Myers, Catherine E; Beck, Kevin D; Moustafa, Ahmed A; Allen, Michael Todd

    2016-01-01

    Recent work has found that personality factors that confer vulnerability to addiction can also affect learning and economic decision making. One personality trait which has been implicated in vulnerability to addiction is intolerance to uncertainty (IU), i.e., a preference for familiar over unknown (possibly better) options. In animals, the motivation to obtain drugs is often assessed through conditioned place preference (CPP), which compares preference for contexts where drug reward was previously received. It is an open question whether participants with high IU also show heightened preference for previously rewarded contexts. To address this question, we developed a novel computer-based CPP task for humans in which participants guide an avatar through a paradigm in which one room contains frequent reward (i.e., rich) and one contains less frequent reward (i.e., poor). Following exposure to both contexts, subjects are assessed for preference to enter the previously rich and previously poor room. Individuals with low IU showed little bias to enter the previously rich room first, and instead entered both rooms at about the same rate which may indicate a foraging behavior. By contrast, those with high IU showed a strong bias to enter the previously rich room first. This suggests an increased tendency to chase reward in the intolerant group, consistent with previously observed behavior in opioid-addicted individuals. Thus, the personality factor of high IU may produce a pre-existing cognitive bias that provides a mechanism to promote decision-making processes that increase vulnerability to addiction.

  13. Cognitive Workload and Fatigue in a Vigilance Dual Task: Miss Errors, False Alarms, and the Effect of Wearing Biometric Sensors While Working.

    PubMed

    Guastello, Stephen J; Reiter, Katherine E; Malon, Matthew

    2016-10-01

    The effects of workload, fatigue, and practice on the performance of cognitive tasks are often intertwined. Previous research has shown that these influences can be separated with the two cusp catastrophe models. This study expanded an earlier investigation of the two models for workload and fatigue in a vigilance task to include a wider range of bifurcation variables that could affect the elasticity versus rigidity of the operator in response to workload and added performance variability resulting from fatigue. The study also responded to a concern in the literature that performance on cognitive tasks can be complicated by adaptive responses to artificial task situations and thus distort underlying cognitive events. Therefore, we also explored whether wearing biometric sensors, frequently used in workload studies, can affect performance dynamics. Participants were 279 undergraduates who responded to target stimuli that appeared on a simulated security camera display at three rates of speed while completing a secondary task. Participants worked alone, in pairs, or in pairs wearing GSR sensors. Results supported the efficacy of the two models and isolated the impact of wearing sensors on the fatigue process. The strongest control variables across both the workload and fatigue models were field independence, anxiety, indecisiveness, inflexibility, secondary task completion, working in pairs, and wearing the sensors. The contributing effect of wearing sensors could possibly extend to other types of wearable technologies. PMID:27550706

  14. Cognitive Workload and Fatigue in a Vigilance Dual Task: Miss Errors, False Alarms, and the Effect of Wearing Biometric Sensors While Working.

    PubMed

    Guastello, Stephen J; Reiter, Katherine E; Malon, Matthew

    2016-10-01

    The effects of workload, fatigue, and practice on the performance of cognitive tasks are often intertwined. Previous research has shown that these influences can be separated with the two cusp catastrophe models. This study expanded an earlier investigation of the two models for workload and fatigue in a vigilance task to include a wider range of bifurcation variables that could affect the elasticity versus rigidity of the operator in response to workload and added performance variability resulting from fatigue. The study also responded to a concern in the literature that performance on cognitive tasks can be complicated by adaptive responses to artificial task situations and thus distort underlying cognitive events. Therefore, we also explored whether wearing biometric sensors, frequently used in workload studies, can affect performance dynamics. Participants were 279 undergraduates who responded to target stimuli that appeared on a simulated security camera display at three rates of speed while completing a secondary task. Participants worked alone, in pairs, or in pairs wearing GSR sensors. Results supported the efficacy of the two models and isolated the impact of wearing sensors on the fatigue process. The strongest control variables across both the workload and fatigue models were field independence, anxiety, indecisiveness, inflexibility, secondary task completion, working in pairs, and wearing the sensors. The contributing effect of wearing sensors could possibly extend to other types of wearable technologies.

  15. A functional approach for research on cognitive control: Analysing cognitive control tasks and their effects in terms of operant conditioning.

    PubMed

    Liefooghe, Baptist; De Houwer, Jan

    2016-02-01

    Cognitive control is an important mental ability that is examined using a multitude of cognitive control tasks and effects. The present paper presents the first steps in the elaboration of a functional approach, which aims to uncover the communalities and differences between different cognitive control tasks and their effects. Based on the idea that responses in cognitive control tasks qualify as operant behaviour, we propose to reinterpret cognitive control tasks in terms of operant contingencies and cognitive control effects as instances of moderated stimulus control. We illustrate how our approach can be used to uncover communalities between topographically different cognitive control tasks and can lead to novel questions about the processes underlying cognitive control.

  16. Neural Correlates of Task Cost for Stance Control with an Additional Motor Task: Phase-Locked Electroencephalogram Responses

    PubMed Central

    Hwang, Ing-Shiou; Huang, Cheng-Ya

    2016-01-01

    With appropriate reallocation of central resources, the ability to maintain an erect posture is not necessarily degraded by a concurrent motor task. This study investigated the neural control of a particular postural-suprapostural procedure involving brain mechanisms to solve crosstalk between posture and motor subtasks. Participants completed a single posture task and a dual-task while concurrently conducting force-matching and maintaining a tilted stabilometer stance at a target angle. Stabilometer movements and event-related potentials (ERPs) were recorded. The added force-matching task increased the irregularity of postural response rather than the size of postural response prior to force-matching. In addition, the added force-matching task during stabilometer stance led to marked topographic ERP modulation, with greater P2 positivity in the frontal and sensorimotor-parietal areas of the N1-P2 transitional phase and in the sensorimotor-parietal area of the late P2 phase. The time-frequency distribution of the ERP primary principal component revealed that the dual-task condition manifested more pronounced delta (1–4 Hz) and beta (13–35 Hz) synchronizations but suppressed theta activity (4–8 Hz) before force-matching. The dual-task condition also manifested coherent fronto-parietal delta activity in the P2 period. In addition to a decrease in postural regularity, this study reveals spatio-temporal and temporal-spectral reorganizations of ERPs in the fronto-sensorimotor-parietal network due to the added suprapostural motor task. For a particular set of postural-suprapostural task, the behavior and neural data suggest a facilitatory role of autonomous postural response and central resource expansion with increasing interregional interactions for task-shift and planning the motor-suprapostural task. PMID:27010634

  17. Dual attention to dynamically structured naturalistic events.

    PubMed

    Stoffregen, T A; Becklen, R C

    1989-12-01

    Videotapes of two naturalistic events, a basketball-like game and a vocalizing human face, were presented in a dual-task situation, with subjects responding to target events in individual episodes. The fact that the stimulus episodes consisted of natural motions permitted subjects to base their attention on the partially determinate structure that characterizes such motions. Simultaneous visual presentations were in full transparent overlap. the auditory presentations were overlapped spatially. Performance on the dual task improved significantly in all experimental conditions over two days of practice. Performance approached control-group ceiling levels for events available to different modalities (hearing and sight). When information was available only in a single modality, performance was lower over-all, but practice effects were still significant. The results are discussed in the context of a cognitive skills approach to attention.

  18. The aging brain shows less flexible reallocation of cognitive resources during dual-task walking: A mobile brain/body imaging (MoBI) study.

    PubMed

    Malcolm, Brenda R; Foxe, John J; Butler, John S; De Sanctis, Pierfilippo

    2015-08-15

    Aging is associated with reduced abilities to selectively allocate attention across multiple domains. This may be particularly problematic during everyday multitasking situations when cognitively demanding tasks are performed while walking. Due to previous limitations in neuroimaging technology, much remains unknown about the cortical mechanisms underlying resource allocation during locomotion. Here, we utilized an EEG-based mobile brain/body imaging (MoBI) technique that integrates high-density event-related potential (ERP) recordings with simultaneously acquired foot-force sensor data to monitor gait patterns and brain activity concurrently. To assess effects of motor load on cognition we evaluated young (N=17; mean age=27.2) and older adults (N=16; mean age=63.9) and compared behavioral and ERP measures associated with performing a Go/No-Go response inhibition task as participants sat stationary or walked on a treadmill. Stride time and variability were also measured during task performance and compared to stride parameters obtained without task performance, thereby assessing effects of cognitive load on gait. Results showed that older, but not young adults' accuracy dropped significantly when performing the inhibitory task while walking. Young adults revealed ERP modulations at relatively early (N2 amplitude reduction) and later (earlier P3 latency) stages within the processing stream as motor load increased while walking. In contrast, older adults' ERP modulations were limited to later processing stages (increased P3 amplitude) of the inhibitory network. The relative delay and attenuation of ERP modulations accompanied by behavioral costs in older participants might indicate an age-associated loss in flexible resource allocation across multiple tasks. Better understanding of the neural underpinnings of these age-related changes may lead to improved strategies to reduce fall risk and enhance mobility in aging. PMID:25988225

  19. The aging brain shows less flexible reallocation of cognitive resources during dual-task walking: A mobile brain/body imaging (MoBI) study.

    PubMed

    Malcolm, Brenda R; Foxe, John J; Butler, John S; De Sanctis, Pierfilippo

    2015-08-15

    Aging is associated with reduced abilities to selectively allocate attention across multiple domains. This may be particularly problematic during everyday multitasking situations when cognitively demanding tasks are performed while walking. Due to previous limitations in neuroimaging technology, much remains unknown about the cortical mechanisms underlying resource allocation during locomotion. Here, we utilized an EEG-based mobile brain/body imaging (MoBI) technique that integrates high-density event-related potential (ERP) recordings with simultaneously acquired foot-force sensor data to monitor gait patterns and brain activity concurrently. To assess effects of motor load on cognition we evaluated young (N=17; mean age=27.2) and older adults (N=16; mean age=63.9) and compared behavioral and ERP measures associated with performing a Go/No-Go response inhibition task as participants sat stationary or walked on a treadmill. Stride time and variability were also measured during task performance and compared to stride parameters obtained without task performance, thereby assessing effects of cognitive load on gait. Results showed that older, but not young adults' accuracy dropped significantly when performing the inhibitory task while walking. Young adults revealed ERP modulations at relatively early (N2 amplitude reduction) and later (earlier P3 latency) stages within the processing stream as motor load increased while walking. In contrast, older adults' ERP modulations were limited to later processing stages (increased P3 amplitude) of the inhibitory network. The relative delay and attenuation of ERP modulations accompanied by behavioral costs in older participants might indicate an age-associated loss in flexible resource allocation across multiple tasks. Better understanding of the neural underpinnings of these age-related changes may lead to improved strategies to reduce fall risk and enhance mobility in aging.

  20. The Personality Trait of Intolerance to Uncertainty Affects Behavior in a Novel Computer-Based Conditioned Place Preference Task

    PubMed Central

    Radell, Milen L.; Myers, Catherine E.; Beck, Kevin D.; Moustafa, Ahmed A.; Allen, Michael Todd

    2016-01-01

    Recent work has found that personality factors that confer vulnerability to addiction can also affect learning and economic decision making. One personality trait which has been implicated in vulnerability to addiction is intolerance to uncertainty (IU), i.e., a preference for familiar over unknown (possibly better) options. In animals, the motivation to obtain drugs is often assessed through conditioned place preference (CPP), which compares preference for contexts where drug reward was previously received. It is an open question whether participants with high IU also show heightened preference for previously rewarded contexts. To address this question, we developed a novel computer-based CPP task for humans in which participants guide an avatar through a paradigm in which one room contains frequent reward (i.e., rich) and one contains less frequent reward (i.e., poor). Following exposure to both contexts, subjects are assessed for preference to enter the previously rich and previously poor room. Individuals with low IU showed little bias to enter the previously rich room first, and instead entered both rooms at about the same rate which may indicate a foraging behavior. By contrast, those with high IU showed a strong bias to enter the previously rich room first. This suggests an increased tendency to chase reward in the intolerant group, consistent with previously observed behavior in opioid-addicted individuals. Thus, the personality factor of high IU may produce a pre-existing cognitive bias that provides a mechanism to promote decision-making processes that increase vulnerability to addiction. PMID:27555829

  1. The Personality Trait of Intolerance to Uncertainty Affects Behavior in a Novel Computer-Based Conditioned Place Preference Task.

    PubMed

    Radell, Milen L; Myers, Catherine E; Beck, Kevin D; Moustafa, Ahmed A; Allen, Michael Todd

    2016-01-01

    Recent work has found that personality factors that confer vulnerability to addiction can also affect learning and economic decision making. One personality trait which has been implicated in vulnerability to addiction is intolerance to uncertainty (IU), i.e., a preference for familiar over unknown (possibly better) options. In animals, the motivation to obtain drugs is often assessed through conditioned place preference (CPP), which compares preference for contexts where drug reward was previously received. It is an open question whether participants with high IU also show heightened preference for previously rewarded contexts. To address this question, we developed a novel computer-based CPP task for humans in which participants guide an avatar through a paradigm in which one room contains frequent reward (i.e., rich) and one contains less frequent reward (i.e., poor). Following exposure to both contexts, subjects are assessed for preference to enter the previously rich and previously poor room. Individuals with low IU showed little bias to enter the previously rich room first, and instead entered both rooms at about the same rate which may indicate a foraging behavior. By contrast, those with high IU showed a strong bias to enter the previously rich room first. This suggests an increased tendency to chase reward in the intolerant group, consistent with previously observed behavior in opioid-addicted individuals. Thus, the personality factor of high IU may produce a pre-existing cognitive bias that provides a mechanism to promote decision-making processes that increase vulnerability to addiction. PMID:27555829

  2. Influence of Pharmacological Manipulations of NMDA and Cholinergic Receptors on Working versus Reference Memory in a Dual Component Odor Span Task

    ERIC Educational Resources Information Center

    MacQueen, David A.; Dalrymple, Savannah R.; Drobes, David J.; Diamond, David M.

    2016-01-01

    Developed as a tool to assess working memory capacity in rodents, the odor span task (OST) has significant potential to advance drug discovery in animal models of psychiatric disorders. Prior investigations indicate OST performance is impaired by systemic administration of N-methyl-D-aspartate receptor (NMDA-r) antagonists and is sensitive to…

  3. (-)-Bornyl acetate induces autonomic relaxation and reduces arousal level after visual display terminal work without any influences of task performance in low-dose condition.

    PubMed

    Matsubara, Eri; Fukagawa, Mio; Okamoto, Tsuyoshi; Ohnuki, Koichiro; Shimizu, Kuniyoshi; Kondo, Ryuichiro

    2011-04-01

    (-)-Bornyl acetate is the main volatile constituent in numerous conifer oils and has a camphoraceous, pine-needle-like odor. It is frequently used as the conifer needle composition in soap, bath products, room sprays, and pharmaceutical products. However, the psychophysiological effects of (-)-bornyl acetate remained unclear. We investigated the effects of breathing air mixed with (-)-bornyl acetate at different doses (low-dose and high-dose conditions) on the individuals during and after VDT (visual display terminal) work using a visual discrimination task. The amounts of (-)-bornyl acetate through our odorant delivery system for 40 min were 279.4 µg in the low-dose and 716.3 µg in the high-dose (-)-bornyl acetate condition. (-)-Bornyl acetate induced changes of autonomic nervous system for relaxation and reduced arousal level after VDT work without any influences of task performance in low-dose condition, but not in high-dose condition.

  4. Do Amnesic Patients with Korsakoff's Syndrome Use Feedback when Making Decisions under Risky Conditions? An Experimental Investigation with the Game of Dice Task with and without Feedback

    ERIC Educational Resources Information Center

    Brand, Matthias; Pawlikowski, Mirko; Labudda, Kirsten; Laier, Christian; von Rothkirch, Nadine; Markowitsch, Hans J.

    2009-01-01

    We investigated the role of feedback processing in decision making under risk conditions in 50 patients with amnesia in the course of alcoholic Korsakoff's syndrome (KS). Half of the patients were administered the Game of Dice Task (GDT) and the remaining 25 patients were examined with a modified version of the GDT in which no feedback was…

  5. The "Reading the Mind in Films" Task [Child Version]: Complex Emotion and Mental State Recognition in Children with and without Autism Spectrum Conditions

    ERIC Educational Resources Information Center

    Golan, Ofer; Baron-Cohen, Simon; Golan, Yael

    2008-01-01

    Children with autism spectrum conditions (ASC) have difficulties recognizing others' emotions. Research has mostly focused on "basic" emotion recognition, devoid of context. This study reports the results of a new task, assessing recognition of "complex" emotions and mental states in social contexts. An ASC group (n = 23) was compared to a general…

  6. Housing conditions affect rat responses to two types of ambiguity in a reward–reward discrimination cognitive bias task

    PubMed Central

    Parker, Richard M.A.; Paul, Elizabeth S.; Burman, Oliver H.P.; Browne, William J.; Mendl, Michael

    2014-01-01

    Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward (‘optimism’) or punishment (‘pessimism’). We investigated whether an automated Reward–Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively ‘pessimistic’, whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases. PMID:25106739

  7. Housing conditions affect rat responses to two types of ambiguity in a reward-reward discrimination cognitive bias task.

    PubMed

    Parker, Richard M A; Paul, Elizabeth S; Burman, Oliver H P; Browne, William J; Mendl, Michael

    2014-11-01

    Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward ('optimism') or punishment ('pessimism'). We investigated whether an automated Reward-Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively 'pessimistic', whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases.

  8. Housing conditions affect rat responses to two types of ambiguity in a reward-reward discrimination cognitive bias task.

    PubMed

    Parker, Richard M A; Paul, Elizabeth S; Burman, Oliver H P; Browne, William J; Mendl, Michael

    2014-11-01

    Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward ('optimism') or punishment ('pessimism'). We investigated whether an automated Reward-Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively 'pessimistic', whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases. PMID:25106739

  9. Corticospinal disinhibition during dual action.

    PubMed

    Sohn, Young H; Kang, Suk Y; Hallett, Mark

    2005-03-01

    When attempting to perform two tasks simultaneously, the human motor as well as the cognitive system shows interference. Such interference often causes altered activation of the cortical area representing each task compared to the single task condition. We investigated changes in corticospinal inhibition during dual action by transcranial magnetic stimulation (TMS). Single-pulse TMS was applied to the left motor cortex, triggered by right leg movement (tibialis anterior muscle) while the right abductor digiti minimi (ADM) muscle was moderately activated (10-20% of the maximal voluntary contraction). The background electromyography (EMG) activity of ADM was measured before and during the leg movement. The silent period (SP) and amplitude of motor evoked potential (MEP) following magnetic stimulation in active ADM were compared for the conditions with and without leg movement. The mean area of the rectified EMG activity of ADM did not alter, while the SP was significantly shortened during leg movement compared to that without leg movement. MEP amplitude was comparable between the two conditions. These results suggest that corticospinal inhibition tested by the SP duration is reduced during the movement of another body part, presumably in order to help maintain muscle force by compensating interference-related alteration in motor cortical activation. PMID:15502976

  10. Questioning and Reading Goals: Information-Seeking Questions Asked on Scientific Texts Read under Different Task Conditions

    ERIC Educational Resources Information Center

    Ishiwa, Koto; Sanjose, Vicente; Otero, Jose

    2013-01-01

    Background: A number of studies report that few questions are asked in classrooms and that many of them are shallow questions. Aims: This study investigates the way in which reading goals determine questioning on scientific texts. Reading goals were manipulated through two different tasks: reading for understanding versus reading to solve a…

  11. Adolescent and adult rats differ in the amnesic effects of acute ethanol in two hippocampus-dependent tasks: Trace and contextual fear conditioning.

    PubMed

    Hunt, Pamela S; Barnet, Robert C

    2016-02-01

    Experience-produced deficits in trace conditioning and context conditioning have been useful tools for examining the role of the hippocampus in learning. It has also been suggested that learning in these tasks is especially vulnerable to neurotoxic effects of alcohol during key developmental periods such as adolescence. In five experiments we systematically examined the presence and source of age-dependent vulnerability to the memory-disrupting effects of acute ethanol in trace conditioning and contextual fear conditioning. In Experiment 1a pre-training ethanol disrupted trace conditioning more strongly in adolescent (postnatal day, PD30-35) than adult rats (PD65-75). In Experiment 1b when pre-training ethanol was accompanied by pre-test ethanol no deficit in trace conditioning was observed in adolescents, suggesting that state-dependent retrieval failure mediated ethanol's disruption of trace conditioning at this age. Experiment 2a and b examined the effect of ethanol pretreatment on context conditioning. Here, adult but not adolescent rats were impaired in conditioned freezing to context cues. Experiment 2c explored state-dependency of this effect. Pre-training ethanol continued to disrupt context conditioning in adults even when ethanol was also administered prior to test. Collectively these findings reveal clear age-dependent and task-dependent vulnerabilities in ethanol's disruptive effects on hippocampus-dependent memory. Adolescents were more disrupted by ethanol in trace conditioning than adults, and adults were more disrupted by ethanol in context conditioning than adolescents. We suggest that adolescents may be more susceptible to changes in internal state (state-dependent retrieval failure) than adults and that ethanol disrupted performance in trace and context conditioning through different mechanisms. Relevance of these findings to theories of hippocampus function is discussed.

  12. Dual-band infrared camera

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Schlemmer, H.

    2005-10-01

    Every year, numerous accidents happen on European roads due to bad visibility (fog, night, heavy rain). Similarly, the dramatic aviation accidents of year 2001 in Milan and Zurich have reminded us that aviation safety is equally affected by reduced visibility. A dual-band thermal imager was developed in order to raise human situation awareness under conditions of reduced visibility especially in the automotive and aeronautical context but also for all transportation or surveillance tasks. The chosen wavelength bands are the Short Wave Infrared SWIR and the Long Wave Infrared LWIR band which are less obscured by reduced visibility conditions than the visible band. Furthermore, our field tests clearly show that the two different spectral bands very often contain complementary information. Pyramidal fusion is used to integrate complementary and redundant features of the multi-spectral images into a fused image which can be displayed on a monitor to provide more and better information for the driver or pilot.

  13. Conditions under Which Children Experience Inhibitory Difficulty with a "Button-Press" Go/No-Go Task

    ERIC Educational Resources Information Center

    Simpson, Andrew; Riggs, Kevin J.

    2006-01-01

    Go/no-go tasks seem to provide a simple marker of inhibitory development in young children. Children are told to respond to one stimulus on go trials but to make no response to another stimulus on no-go trials; responding on no-go trials is assumed to reflect a failure to inhibit the go response. However, there is evidence to suggest that a type…

  14. Differential effects of four token conditions on rate and choice of responding in a matching-to-sample task.

    PubMed

    Repp, A C; Klett, S Z; Sosebee, L H; Speir, N C

    1975-07-01

    In a two-phase experiment, four different token conditions were presented each session to retarded students in a TMR class. In Phase 1, students responded by matching-to-sample under the following conditions: (A) correct responses produced exchangeable tokens, (B) correct responses produced exchangeable tokens and incorrect responses lost tokens, (C) correct responses produced nonexchangeable tokens, and (D) no-tokens given. In Phase 2, the students chose the condition in which they worked. Results showed that responses cost decreased errors but did not influence correct responding, that each baseline condition produced less correct responding than the token conditions, and that Condition C produced more responding than D. Phase 2 results showed a preference for Condition A and no difference between Conditions B and C. Results were discussed in terms of baselines, response cost, and type of datum.

  15. Analytical prediction and experimental verification of performance at various operating conditions of a dual-mode traveling wave tube with multistage depressed collectors

    NASA Technical Reports Server (NTRS)

    Dayton, J. A., Jr.; Kosmahl, H. G.; Ramins, P.; Stankiewicz, N.

    1981-01-01

    A comparison of analytical and experimental results is presented for a high performance dual-mode traveling wave tube (TWT) operated over a wide range conditions. The computations are carried out with advanced multidimensional computer programs. These programs model the electron beam as a series of disks or rings of charge and follow their trajectories from the rf input of the TWT through the slow-wave structure refocusing system to their points of impacts in the depressed collector. TWT performance, collector efficiency, and collector current distribution are computed and compared with measurements. Very good agreement was obtained between computed and measured TWT performance and collector efficiencies, and the computer design of a highly efficient collector was demonstrated.

  16. An Analysis of Early vs. Later Responses on a Divergent Production Task across Three Time Press Conditions.

    ERIC Educational Resources Information Center

    Johns, Gregg A.; Morse, Linda W.; Morse, David T.

    2001-01-01

    This study examined the effects of three time-press and three creative-prompt conditions on early vs. later trial originality scores for three divergent production stimuli with 91 undergraduate students. Findings indicated a higher frequency of originality scores for the latter portions of trials for all time-press and prompting conditions.…

  17. Boundary conditions for the influence of unfamiliar non-target primes in unconscious evaluative priming: The moderating role of attentional task sets.

    PubMed

    Kiefer, Markus; Sim, Eun-Jim; Wentura, Dirk

    2015-09-01

    Evaluative priming by masked emotional stimuli that are not consciously perceived has been taken as evidence that affective stimulus evaluation can also occur unconsciously. However, as masked priming effects were small and frequently observed only for familiar primes that there also presented as visible targets in an evaluative decision task, priming was thought to reflect primarily response activation based on acquired S-R associations and not evaluative semantic stimulus analysis. The present study therefore assessed across three experiments boundary conditions for the emergence of masked evaluative priming effects with unfamiliar primes in an evaluative decision task and investigated the role of the frequency of target repetition on priming with pictorial and verbal stimuli. While familiar primes elicited robust priming effects in all conditions, priming effects by unfamiliar primes were reliably obtained for low repetition (pictures) or unrepeated targets (words), but not for targets repeated at a high frequency. This suggests that unfamiliar masked stimuli only elicit evaluative priming effects when the task set associated with the visible target involves evaluative semantic analysis and is not based on S-R triggered responding as for high repetition targets. The present results therefore converge with the growing body of evidence demonstrating attentional control influences on unconscious processing. PMID:25680827

  18. A Study of Some Conditions Relating to the Retarded Adult's Stereotyped Responding in a Binary-Choice Task

    ERIC Educational Resources Information Center

    And Others; Siegel, Paul S.

    1977-01-01

    Examined in a longitudinal study were the effects of conditions on alternation and perseveration of eight moderately and severely mentally retarded institutionalized adults. Available from: Ablex Publishing Corporation, 355 Chestnut Street, Norwood, New Jersey 07648. (CL)

  19. Modelling Individual Differences in the Form of Pavlovian Conditioned Approach Responses: A Dual Learning Systems Approach with Factored Representations

    PubMed Central

    Lesaint, Florian; Sigaud, Olivier; Flagel, Shelly B.; Robinson, Terry E.; Khamassi, Mehdi

    2014-01-01

    Reinforcement Learning has greatly influenced models of conditioning, providing powerful explanations of acquired behaviour and underlying physiological observations. However, in recent autoshaping experiments in rats, variation in the form of Pavlovian conditioned responses (CRs) and associated dopamine activity, have questioned the classical hypothesis that phasic dopamine activity corresponds to a reward prediction error-like signal arising from a classical Model-Free system, necessary for Pavlovian conditioning. Over the course of Pavlovian conditioning using food as the unconditioned stimulus (US), some rats (sign-trackers) come to approach and engage the conditioned stimulus (CS) itself – a lever – more and more avidly, whereas other rats (goal-trackers) learn to approach the location of food delivery upon CS presentation. Importantly, although both sign-trackers and goal-trackers learn the CS-US association equally well, only in sign-trackers does phasic dopamine activity show classical reward prediction error-like bursts. Furthermore, neither the acquisition nor the expression of a goal-tracking CR is dopamine-dependent. Here we present a computational model that can account for such individual variations. We show that a combination of a Model-Based system and a revised Model-Free system can account for the development of distinct CRs in rats. Moreover, we show that revising a classical Model-Free system to individually process stimuli by using factored representations can explain why classical dopaminergic patterns may be observed for some rats and not for others depending on the CR they develop. In addition, the model can account for other behavioural and pharmacological results obtained using the same, or similar, autoshaping procedures. Finally, the model makes it possible to draw a set of experimental predictions that may be verified in a modified experimental protocol. We suggest that further investigation of factored representations in

  20. Modelling individual differences in the form of Pavlovian conditioned approach responses: a dual learning systems approach with factored representations.

    PubMed

    Lesaint, Florian; Sigaud, Olivier; Flagel, Shelly B; Robinson, Terry E; Khamassi, Mehdi

    2014-02-01

    Reinforcement Learning has greatly influenced models of conditioning, providing powerful explanations of acquired behaviour and underlying physiological observations. However, in recent autoshaping experiments in rats, variation in the form of Pavlovian conditioned responses (CRs) and associated dopamine activity, have questioned the classical hypothesis that phasic dopamine activity corresponds to a reward prediction error-like signal arising from a classical Model-Free system, necessary for Pavlovian conditioning. Over the course of Pavlovian conditioning using food as the unconditioned stimulus (US), some rats (sign-trackers) come to approach and engage the conditioned stimulus (CS) itself - a lever - more and more avidly, whereas other rats (goal-trackers) learn to approach the location of food delivery upon CS presentation. Importantly, although both sign-trackers and goal-trackers learn the CS-US association equally well, only in sign-trackers does phasic dopamine activity show classical reward prediction error-like bursts. Furthermore, neither the acquisition nor the expression of a goal-tracking CR is dopamine-dependent. Here we present a computational model that can account for such individual variations. We show that a combination of a Model-Based system and a revised Model-Free system can account for the development of distinct CRs in rats. Moreover, we show that revising a classical Model-Free system to individually process stimuli by using factored representations can explain why classical dopaminergic patterns may be observed for some rats and not for others depending on the CR they develop. In addition, the model can account for other behavioural and pharmacological results obtained using the same, or similar, autoshaping procedures. Finally, the model makes it possible to draw a set of experimental predictions that may be verified in a modified experimental protocol. We suggest that further investigation of factored representations in computational

  1. Modelling individual differences in the form of Pavlovian conditioned approach responses: a dual learning systems approach with factored representations.

    PubMed

    Lesaint, Florian; Sigaud, Olivier; Flagel, Shelly B; Robinson, Terry E; Khamassi, Mehdi

    2014-02-01

    Reinforcement Learning has greatly influenced models of conditioning, providing powerful explanations of acquired behaviour and underlying physiological observations. However, in recent autoshaping experiments in rats, variation in the form of Pavlovian conditioned responses (CRs) and associated dopamine activity, have questioned the classical hypothesis that phasic dopamine activity corresponds to a reward prediction error-like signal arising from a classical Model-Free system, necessary for Pavlovian conditioning. Over the course of Pavlovian conditioning using food as the unconditioned stimulus (US), some rats (sign-trackers) come to approach and engage the conditioned stimulus (CS) itself - a lever - more and more avidly, whereas other rats (goal-trackers) learn to approach the location of food delivery upon CS presentation. Importantly, although both sign-trackers and goal-trackers learn the CS-US association equally well, only in sign-trackers does phasic dopamine activity show classical reward prediction error-like bursts. Furthermore, neither the acquisition nor the expression of a goal-tracking CR is dopamine-dependent. Here we present a computational model that can account for such individual variations. We show that a combination of a Model-Based system and a revised Model-Free system can account for the development of distinct CRs in rats. Moreover, we show that revising a classical Model-Free system to individually process stimuli by using factored representations can explain why classical dopaminergic patterns may be observed for some rats and not for others depending on the CR they develop. In addition, the model can account for other behavioural and pharmacological results obtained using the same, or similar, autoshaping procedures. Finally, the model makes it possible to draw a set of experimental predictions that may be verified in a modified experimental protocol. We suggest that further investigation of factored representations in computational

  2. Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks.

    PubMed

    Yoto, A; Murao, S; Motoki, M; Yokoyama, Y; Horie, N; Takeshima, K; Masuda, K; Kim, M; Yokogoshi, H

    2012-09-01

    γ-Aminobutyric acid (GABA) is a kind of amino acid contained in green tea leaves and other foods. Several reports have shown that GABA might affect brain protein synthesis, improve many brain functions such as memory and study capability, lower the blood pressure of spontaneously hypertensive rats, and may also have a relaxation effect in humans. However, the evidence for its mood-improving function is still not sufficient. In this study, we investigated how the oral intake of GABA influences human adults psychologically and physiologically under a condition of mental stress. Sixty-three adults (28 males, 35 females) participated in a randomized, single blind, placebo-controlled, crossover-designed study over two experiment days. Capsules containing 100 mg of GABA or dextrin as a placebo were used as test samples. The results showed that EEG activities including alpha band and beta band brain waves decreased depending on the mental stress task loads, and the condition of 30 min after GABA intake diminished this decrease compared with the placebo condition. That is to say, GABA might have alleviated the stress induced by the mental tasks. This effect also corresponded with the results of the POMS scores. PMID:22203366

  3. Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks.

    PubMed

    Yoto, A; Murao, S; Motoki, M; Yokoyama, Y; Horie, N; Takeshima, K; Masuda, K; Kim, M; Yokogoshi, H

    2012-09-01

    γ-Aminobutyric acid (GABA) is a kind of amino acid contained in green tea leaves and other foods. Several reports have shown that GABA might affect brain protein synthesis, improve many brain functions such as memory and study capability, lower the blood pressure of spontaneously hypertensive rats, and may also have a relaxation effect in humans. However, the evidence for its mood-improving function is still not sufficient. In this study, we investigated how the oral intake of GABA influences human adults psychologically and physiologically under a condition of mental stress. Sixty-three adults (28 males, 35 females) participated in a randomized, single blind, placebo-controlled, crossover-designed study over two experiment days. Capsules containing 100 mg of GABA or dextrin as a placebo were used as test samples. The results showed that EEG activities including alpha band and beta band brain waves decreased depending on the mental stress task loads, and the condition of 30 min after GABA intake diminished this decrease compared with the placebo condition. That is to say, GABA might have alleviated the stress induced by the mental tasks. This effect also corresponded with the results of the POMS scores.

  4. Different MK-801 administration schedules induce mild to severe learning impairments in an operant conditioning task: role of buspirone and risperidone in ameliorating these cognitive deficits.

    PubMed

    Rapanelli, Maximiliano; Frick, Luciana Romina; Bernardez-Vidal, Micaela; Zanutto, Bonifacio Silvano

    2013-11-15

    Blockade of N-methyl-d-aspartate receptor (NMDA) by the noncompetitive NMDA receptor (NMDAR) antagonist MK-801 produces behavioral abnormalities and alterations in prefrontal cortex (PFC) functioning. Due to the critical role of the PFC in operant conditioning task learning, we evaluated the effects of acute, repeated postnatal injections of MK-801 (0.1mg/kg) on learning performance. We injected Long-Evans rats i.p. with MK-801 (0.1mg/kg) using three different administration schedules: injection 40 min before beginning the task (during) (n=12); injection twice daily for six consecutive days prior to beginning the experimental procedures (prior) (n=12); or twice daily subcutaneous injections from postnatal day 7 to 11 (postnatal) (n=12). Next, we orally administered risperidone (serotonin receptor 2A and dopamine receptor 2 antagonist, 1mg/kg) or buspirone (serotonin receptor 1A partial agonist, 10mg/kg) to animals treated with the MK-801 schedule described above. The postnatal and prior administration schedules produced severe learning deficits, whereas injection of MK-801 just before training sessions had only mild effects on acquisition of an operant conditioning. Risperidone was able to reverse the detrimental effect of MK-801 in the animals that were treated with MK-801 during and prior training sessions. In contrast, buspirone was only effective at mitigating the cognitive deficits induced by MK-801 when administered during the training procedures. The data demonstrates that NMDA antagonism disrupts basic mechanisms of learning in a simple PFC-mediated operant conditioning task, and that buspirone and risperidone failed to attenuate the learning deficits when NMDA neurotransmission was blocked in the early stages of the postnatal period.

  5. Differential biofilm formation and chemical disinfection resistance of sessile cells of Listeria monocytogenes strains under monospecies and dual-species (with Salmonella enterica) conditions.

    PubMed

    Kostaki, Maria; Chorianopoulos, Nikos; Braxou, Elli; Nychas, George-John; Giaouris, Efstathios

    2012-04-01

    This study aimed to investigate the possible influence of bacterial intra- and interspecies interactions on the ability of Listeria monocytogenes and Salmonella enterica to develop mixed-culture biofilms on an abiotic substratum, as well as on the subsequent resistance of sessile cells to chemical disinfection. Initially, three strains from each species were selected and left to attach and form biofilms on stainless steel (SS) coupons incubated at 15°C for 144 h, in periodically renewable tryptone soy broth (TSB), under either monoculture or mixed-culture (mono-/dual-species) conditions. Following biofilm formation, mixed-culture sessile communities were subjected to 6-min disinfection treatments with (i) benzalkonium chloride (50 ppm), (ii) sodium hypochlorite (10 ppm), (iii) peracetic acid (10 ppm), and (iv) a mixture of hydrogen peroxide (5 ppm) and peracetic acid (5 ppm). Results revealed that both species reached similar biofilm counts (ca. 10(5) CFU cm(-2)) and that, in general, interspecies interactions did not have any significant effect either on the biofilm-forming ability (as this was assessed by agar plating enumeration of the mechanically detached biofilm bacteria) or on the antimicrobial resistance of each individual species. Interestingly, pulsed-field gel electrophoresis (PFGE) analysis clearly showed that the three L. monocytogenes strains did not contribute at the same level either to the formation of mixed-culture sessile communities (mono-/dual species) or to their antimicrobial recalcitrance. Additionally, the simultaneous existence inside the biofilm structure of S. enterica cells seemed to influence the occurrence and resistance pattern of L. monocytogenes strains. In sum, this study highlights the impact of microbial interactions taking place inside a mixed-culture sessile community on both its population dynamics and disinfection resistance.

  6. Differential Biofilm Formation and Chemical Disinfection Resistance of Sessile Cells of Listeria monocytogenes Strains under Monospecies and Dual-Species (with Salmonella enterica) Conditions

    PubMed Central

    Kostaki, Maria; Chorianopoulos, Nikos; Braxou, Elli; Nychas, George-John

    2012-01-01

    This study aimed to investigate the possible influence of bacterial intra- and interspecies interactions on the ability of Listeria monocytogenes and Salmonella enterica to develop mixed-culture biofilms on an abiotic substratum, as well as on the subsequent resistance of sessile cells to chemical disinfection. Initially, three strains from each species were selected and left to attach and form biofilms on stainless steel (SS) coupons incubated at 15°C for 144 h, in periodically renewable tryptone soy broth (TSB), under either monoculture or mixed-culture (mono-/dual-species) conditions. Following biofilm formation, mixed-culture sessile communities were subjected to 6-min disinfection treatments with (i) benzalkonium chloride (50 ppm), (ii) sodium hypochlorite (10 ppm), (iii) peracetic acid (10 ppm), and (iv) a mixture of hydrogen peroxide (5 ppm) and peracetic acid (5 ppm). Results revealed that both species reached similar biofilm counts (ca. 105 CFU cm−2) and that, in general, interspecies interactions did not have any significant effect either on the biofilm-forming ability (as this was assessed by agar plating enumeration of the mechanically detached biofilm bacteria) or on the antimicrobial resistance of each individual species. Interestingly, pulsed-field gel electrophoresis (PFGE) analysis clearly showed that the three L. monocytogenes strains did not contribute at the same level either to the formation of mixed-culture sessile communities (mono-/dual species) or to their antimicrobial recalcitrance. Additionally, the simultaneous existence inside the biofilm structure of S. enterica cells seemed to influence the occurrence and resistance pattern of L. monocytogenes strains. In sum, this study highlights the impact of microbial interactions taking place inside a mixed-culture sessile community on both its population dynamics and disinfection resistance. PMID:22307304

  7. Study Task for Determining the Effects of Boost-Phase Environments on Densified Propellants Thermal Conditions for Expendable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Haberbusch, Mark S.; Meyer, Michael L. (Technical Monitor)

    2002-01-01

    A thermodynamic study has been conducted that investigated the effects of the boost-phase environment on densified propellant thermal conditions for expendable launch vehicles. Two thermodynamic models were developed and utilized to bound the expected thermodynamic conditions inside the cryogenic liquid hydrogen and oxygen propellant tanks of an Atlas IIAS/Centaur launch vehicle during the initial phases of flight. The ideal isentropic compression model was developed to predict minimum pressurant gas requirements. The thermal equilibrium model was developed to predict the maximum pressurant gas requirements. The models were modified to simulate the required flight tank pressure profiles through ramp pressurization, liquid expulsion, and tank venting. The transient parameters investigated were: liquid temperature, liquid level, and pressurant gas consumption. Several mission scenarios were analyzed using the thermodynamic models, and the results indicate that flying an Atlas IIAS launch vehicle with densified propellants is feasible and beneficial but may require some minor changes to the vehicle.

  8. Functional disconnection of the substantia nigra pars compacta from the pedunculopontine nucleus impairs learning of a conditioned avoidance task.

    PubMed

    Bortolanza, Mariza; Wietzikoski, Evellyn C; Boschen, Suelen L; Dombrowski, Patricia A; Latimer, Mary; Maclaren, Duncan A A; Winn, Philip; Da Cunha, Claudio

    2010-09-01

    The pedunculopontine tegmental nucleus (PPTg) targets nuclei in the basal ganglia, including the substantia nigra pars compacta (SNc), in which neuronal loss occurs in Parkinson's disease, a condition in which patients show cognitive as well as motor disturbances. Partial loss and functional abnormalities of neurons in the PPTg are also associated with Parkinson's disease. We hypothesized that the interaction of PPTg and SNc might be important for cognitive impairments and so investigated whether disrupting the connections between the PPTg and SNc impaired learning of a conditioned avoidance response (CAR) by male Wistar rats. The following groups were tested: PPTg unilateral; SNc unilateral; PPTg-SNc ipsilateral (ipsilateral lesions in PPTg and SNc); PPTg-SNc contralateral (contralateral lesions in PPTg and SNc); sham lesions (of each type). SNc lesions were made with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine HCl (MPTP, 0.6micromol); PPTg lesions with ibotenate (24nmol). After recovery, all rats underwent 50-trial sessions of 2-way active avoidance conditioning for 3 consecutive days. Rats with unilateral lesions in PPTg or SNc learnt this, however rats with contralateral (but not ipsilateral) combined lesions in both structures presented no sign of learning. This effect was not likely to be due to sensorimotor impairment because lesions did not affect reaction time to the tone or footshock during conditioning. However, an increased number of non-responses were observed in the rats with contralateral lesions. The results support the hypothesis that a functional interaction between PPTg and SNc is needed for CAR learning and performance.

  9. Pre-test metyrapone impairs memory recall in fear conditioning tasks: lack of interaction with β-adrenergic activity

    PubMed Central

    Careaga, Mariella B. L.; Tiba, Paula A.; Ota, Simone M.; Suchecki, Deborah

    2015-01-01

    Cognitive processes, such as learning and memory, are essential for our adaptation to environmental changes and consequently for survival. Numerous studies indicate that hormones secreted during stressful situations, such as glucocorticoids (GCs), adrenaline and noradrenaline, regulate memory functions, modulating aversive memory consolidation and retrieval, in an interactive and complementary way. Thus, the facilitatory effects of GCs on memory consolidation as well as their suppressive effects on retrieval are substantially explained by this interaction. On the other hand, low levels of GCs are also associated with negative effects on memory consolidation and retrieval and the mechanisms involved are not well understood. The present study sought to investigate the consequences of blocking the rise of GCs on fear memory retrieval in multiple tests, assessing the participation of β-adrenergic signaling on this effect. Metyrapone (GCs synthesis inhibitor; 75 mg/kg), administered 90 min before the first test of contextual or tone fear conditioning (TFC), negatively affected animals’ performances, but this effect did not persist on a subsequent test, when the conditioned response was again expressed. This result suggested that the treatment impaired fear memory retrieval during the first evaluation. The administration immediately after the first test did not affect the animals’ performances in contextual fear conditioning (CFC), suggesting that the drug did not interfere with processes triggered by memory reactivation. Moreover, metyrapone effects were independent of β-adrenergic signaling, since concurrent administration with propranolol (2 mg/kg), a β-adrenergic antagonist, did not modify the effects induced by metyrapone alone. These results demonstrate that pre-test metyrapone administration led to negative effects on fear memory retrieval and this action was independent of a β-adrenergic signaling. PMID:25784866

  10. Task reports on developing techniques for scattering by 3D composite structures and to generate new solutions in diffraction theory using higher order boundary conditions

    NASA Technical Reports Server (NTRS)

    Volakis, John L.

    1991-01-01

    There are two tasks described in this report. First, an extension of a two dimensional formulation is presented for a three dimensional body of revolution. A Fourier series expansion of the vector electric and magnetic fields is employed to reduce the dimensionality of the system, and an exact boundary condition is employed to terminate the mesh. The mesh termination boundary is chosen such that it leads to convolutional boundary operators for low O(n) memory demand. Second, rigorous uniform geometrical theory of diffraction (UTD) diffraction coefficients are presented for a coated convex cylinder simulated with generalized impedance boundary conditions. Ray solutions are obtained which remain valid in the transition region and reduce uniformly those in the deep lit and shadow regions. A uniform asymptotic solution is also presented for observations in the close vicinity of the cylinder.

  11. Task reports on developing techniques for scattering by 3D composite structures and to generate new solutions in diffraction theory using higher order boundary conditions

    NASA Technical Reports Server (NTRS)

    Volakis, John L.

    1990-01-01

    There are two tasks described in this report. First, an extension of a two dimensional formulation is presented for a three dimensional body of revolution. With the introduction of a Fourier expansion of the vector electric and magnetic fields, a coupled two dimensional system is generated and solved via the finite element method. An exact boundary condition is employed to terminate the mesh and the fast fourier transformation is used to evaluate the boundary integrals for low O(n) memory demand when an iterative solution algorithm is used. Second, the diffraction by a material discontinuity in a thick dielectric/ferrite layer is considered by modeling the layer as a distributed current sheet obeying generalized sheet transition conditions (GSTC's).

  12. Identifying optimum performance trade-offs using a cognitively bounded rational analysis model of discretionary task interleaving.

    PubMed

    Janssen, Christian P; Brumby, Duncan P; Dowell, John; Chater, Nick; Howes, Andrew

    2011-01-01

    We report the results of a dual-task study in which participants performed a tracking and typing task under various experimental conditions. An objective payoff function was used to provide explicit feedback on how participants should trade off performance between the tasks. Results show that participants' dual-task interleaving strategy was sensitive to changes in the difficulty of the tracking task and resulted in differences in overall task performance. To test the hypothesis that people select strategies that maximize payoff, a Cognitively Bounded Rational Analysis model was developed. This analysis evaluated a variety of dual-task interleaving strategies to identify the optimal strategy for maximizing payoff in each condition. The model predicts that the region of optimum performance is different between experimental conditions. The correspondence between human data and the prediction of the optimal strategy is found to be remarkably high across a number of performance measures. This suggests that participants were honing their behavior to maximize payoff. Limitations are discussed.

  13. The effect of oxygen supply on the dual growth kinetics of Acidithiobacillus thiooxidans under acidic conditions for biogas desulfurization.

    PubMed

    Namgung, Hyeong-Kyu; Song, JiHyeon

    2015-01-27

    In this study, to simulate a biogas desulfurization process, a modified Monod-Gompertz kinetic model incorporating a dissolved oxygen (DO) effect was proposed for a sulfur-oxidizing bacterial (SOB) strain, Acidithiobacillus thiooxidans, under extremely acidic conditions of pH 2. The kinetic model was calibrated and validated using experimental data obtained from a bubble-column bioreactor. The SOB strain was effective for H2S degradation, but the H2S removal efficiency dropped rapidly at DO concentrations less than 2.0 mg/L. A low H2S loading was effectively treated with oxygen supplied in a range of 2%-6%, but a H2S guideline of 10 ppm could not be met, even with an oxygen supply greater than 6%, when the H2S loading was high at a short gas retention time of 1 min and a H2S inlet concentration of 5000 ppm. The oxygen supply should be increased in the aerobic desulfurization to meet the H2S guideline; however, the excess oxygen above the optimum was not effective because of the decline in oxygen efficiency. The model estimation indicated that the maximum H2S removal rate was approximately 400 ppm/%-O2 at the influent oxygen concentration of 4.9% under the given condition. The kinetic model with a low DO threshold for the interacting substrates was a useful tool to simulate the effect of the oxygen supply on the H2S removal and to determine the optimal oxygen concentration.

  14. The Effect of Oxygen Supply on the Dual Growth Kinetics of Acidithiobacillus thiooxidans under Acidic Conditions for Biogas Desulfurization

    PubMed Central

    Namgung, Hyeong-Kyu; Song, JiHyeon

    2015-01-01

    In this study, to simulate a biogas desulfurization process, a modified Monod-Gompertz kinetic model incorporating a dissolved oxygen (DO) effect was proposed for a sulfur-oxidizing bacterial (SOB) strain, Acidithiobacillus thiooxidans, under extremely acidic conditions of pH 2. The kinetic model was calibrated and validated using experimental data obtained from a bubble-column bioreactor. The SOB strain was effective for H2S degradation, but the H2S removal efficiency dropped rapidly at DO concentrations less than 2.0 mg/L. A low H2S loading was effectively treated with oxygen supplied in a range of 2%–6%, but a H2S guideline of 10 ppm could not be met, even with an oxygen supply greater than 6%, when the H2S loading was high at a short gas retention time of 1 min and a H2S inlet concentration of 5000 ppm. The oxygen supply should be increased in the aerobic desulfurization to meet the H2S guideline; however, the excess oxygen above the optimum was not effective because of the decline in oxygen efficiency. The model estimation indicated that the maximum H2S removal rate was approximately 400 ppm/%-O2 at the influent oxygen concentration of 4.9% under the given condition. The kinetic model with a low DO threshold for the interacting substrates was a useful tool to simulate the effect of the oxygen supply on the H2S removal and to determine the optimal oxygen concentration. PMID:25633028

  15. Multicomponent physical exercise with simultaneous cognitive training to enhance dual-task walking of older adults: a secondary analysis of a 6-month randomized controlled trial with 1-year follow-up

    PubMed Central

    Eggenberger, Patrick; Theill, Nathan; Holenstein, Stefan; Schumacher, Vera; de Bruin, Eling D

    2015-01-01

    Background About one-third of people older than 65 years fall at least once a year. Physical exercise has been previously demonstrated to improve gait, enhance physical fitness, and prevent falls. Nonetheless, the addition of cognitive training components may potentially increase these effects, since cognitive impairment is related to gait irregularities and fall risk. We hypothesized that simultaneous cognitive–physical training would lead to greater improvements in dual-task (DT) gait compared to exclusive physical training. Methods Elderly persons older than 70 years and without cognitive impairment were randomly assigned to the following groups: 1) virtual reality video game dancing (DANCE), 2) treadmill walking with simultaneous verbal memory training (MEMORY), or 3) treadmill walking (PHYS). Each program was complemented with strength and balance exercises. Two 1-hour training sessions per week over 6 months were applied. Gait variables, functional fitness (Short Physical Performance Battery, 6-minute walk), and fall frequencies were assessed at baseline, after 3 months and 6 months, and at 1-year follow-up. Multiple regression analyses with planned comparisons were carried out. Results Eighty-nine participants were randomized to three groups initially; 71 completed the training and 47 were available at 1-year follow-up. DANCE/MEMORY showed a significant advantage compared to PHYS in DT costs of step time variability at fast walking (P=0.044). Training-specific gait adaptations were found on comparing DANCE and MEMORY: DANCE reduced step time at fast walking (P=0.007) and MEMORY reduced gait variability in DT and DT costs at preferred walking speed (both trend P=0.062). Global linear time effects showed improved gait (P<0.05), functional fitness (P<0.05), and reduced fall frequency (−77%, P<0.001). Only single-task fast walking, gait variability at preferred walking speed, and Short Physical Performance Battery were reduced at follow-up (all P<0.05 or

  16. Effect of various surface conditioning methods on the adhesion of dual-cure resin cement with MDP functional monomer to zirconia after thermal aging.

    PubMed

    Ozcan, Mutlu; Nijhuis, Henk; Valandro, Luiz Felipe

    2008-01-01

    This study evaluated the effect of chairside and laboratory types of surface conditioning methods on the adhesion of dual-cure resin cement with MDP functional monomer to zirconia ceramic after thermocycling. Disk-shaped (diameter: 10 mm, thickness: 2 mm) Y-TZP ceramics (Lava, 3M ESPE) were used (N=40) and finished with wet 1200-grit silicon carbide abrasive paper. Specimens were randomly divided into four experimental groups according to the following surface conditioning methods (n=10 per group): Group 1--Chairside airborne particle abrasion with 50-microm Al2O2 + Alloy Primer (Kuraray); Group 2--Airborne particle abrasion with 50-microm Al2O3 + Cesead II Opaque Primer (Kuraray); Group 3--Airborne particle abrasion with 50-microm A12O3 + Silano-Pen + silane coupling agent (Bredent); Group 4--Laboratory tribochemical silica coating (110-microm Al2O3 + 110-microm SiOx) (Rocatec) + silane coupling agent (ESPE-Sil). Adhesive cement, Panavia F 2.0 (Kuraray), was bonded incrementally to the ceramic surfaces using polyethylene molds (diameter: 3.6 mm, height: 5 mm). All specimens were thermocycled (5 and 55 degrees C, 6,000 cycles) and subjected to shear bond strength test (1 mm/min). Data were statistically analyzed (one-way ANOVA, alpha=0.05), whereby no significant differences were found among the four groups (8.43+/-1.3, 8.98+/-3.6, 12.02+/-6.7, and 8.23+/-3.8 MPa) (p=0.1357). Therefore, the performance of chairside conditioning methods used for zirconia was on par with the laboratory alternative tested.

  17. Performance in Dual Tasks. Final Report.

    ERIC Educational Resources Information Center

    Hunt, Earl; Lansman, Marcy

    This project was designed to construct a single theoretical framework for the analysis of problem solving and real time "attention and performance" behavior. The model was developed as a computer program. It was designed in a similar manner to that of various problem solving simulations that use the "production system" approach. The program has…

  18. The effect of cognitive task complexity on gait stability in adolescents following concussion.

    PubMed

    Howell, David R; Osternig, Louis R; Koester, Michael C; Chou, Li-Shan

    2014-06-01

    Concussion has been reported to result in disturbances to motor and cognitive functions. One way to examine these disturbances is through a dual-task assessment. Many secondary cognitive tasks have been proposed as appropriate tools during concussion assessment; however, task complexity has not been compared within a dual-task investigation. The purpose of this study was to prospectively examine how gait balance control was affected by three secondary cognitive tasks of varying complexity following concussion. Forty-six adolescents completed a dual-task walking protocol which included walking without any cognitive task (WALK), walking while completing a single auditory Stroop (SAS), multiple auditory Stroop (MAS), and a question and answer task (Q&A). Those who sustained a concussion (n = 23, mean age 15.4 ± 1.3 years) reported to the laboratory within 72 h of injury and in the following time increments: 1 week, 2 weeks, 1 month, and 2 months post-injury. Twenty-three healthy control subjects (mean age 15.4 ± 1.3 years), individually matched to each concussion subject, completed the same protocol in similar time increments. The concussion group demonstrated greater total center of mass (COM) medial/lateral displacement in the MAS and Q&A conditions compared with the control group. The concussion group also displayed the greatest peak COM anterior velocity in the least complex condition (WALK), and a significant decrease was observed as task complexity increased (SAS > MAS > Q&A). These findings indicate that gait balance control may be affected by task complexity following concussion and represent a way to identify motor recovery following concussion. PMID:24531643

  19. Conditional recall and the frequency effect in the serial recall task: an examination of item-to-item associativity.

    PubMed

    Miller, Leonie M; Roodenrys, Steven

    2012-11-01

    The frequency effect in short-term serial recall is influenced by the composition of lists. In pure lists, a robust advantage in the recall of high-frequency (HF) words is observed, yet in alternating mixed lists, HF and low-frequency (LF) words are recalled equally well. It has been argued that the preexisting associations between all list items determine a single, global level of supportive activation that assists item recall. Preexisting associations between items are assumed to be a function of language co-occurrence; HF-HF associations are high, LF-LF associations are low, and mixed associations are intermediate in activation strength. This account, however, is based on results when alternating lists with equal numbers of HF and LF words were used. It is possible that directional association between adjacent list items is responsible for the recall patterns reported. In the present experiment, the recall of three forms of mixed lists-those with equal numbers of HF and LF items and pure lists-was examined to test the extent to which item-to-item associations are present in serial recall. Furthermore, conditional probabilities were used to examine more closely the evidence for a contribution, since correct-in-position scoring may mask recall that is dependent on the recall of prior items. The results suggest that an item-to-item effect is clearly present for early but not late list items, and they implicate an additional factor, perhaps the availability of resources at output, in the recall of late list items.

  20. High versus low fat/sugar food affects the behavioral, but not the cortisol response of marmoset monkeys in a conditioned-place-preference task.

    PubMed

    Duarte, R B M; Patrono, E; Borges, A C; Tomaz, C; Ventura, R; Gasbarri, A; Puglisi-Allegra, S; Barros, M

    2015-02-01

    The effect of a high (chocolate) versus low fat/sugar (chow) food on a conditioned-place-preference (CPP) task was evaluated in marmoset monkeys. Anxiety-related behaviors and cortisol levels before and after the CPP task were also measured. Subjects were habituated to a two-compartment CPP box and then, on alternate days, had access to only one compartment during daily 15-min conditionings, for a total of 14 trials. Marmosets were provisioned with chocolate chips in the CC-paired compartment on odd-numbered trials and standard chow in the CW-paired compartment on even-numbered trials. They were then tested for preferring the CC-paired context after a 24-h interval. During the conditioning, a significantly greater amount (in kcal/trial) of chocolate was consumed than chow, yet the foraging pattern of both food types was similar. On the test trial, the time spent in the CC-paired context increased significantly compared to pre-CPP levels, yet this response was not readily predicted by baseline behavioral or cortisol levels. Also, the chocolate CPP response was positively correlated with foraging time, rather than the amount of calories consumed. The sudden absence of the food increased exploration, while the chocolate CPP effect was associated with vigilance - both anxiety-related behaviors in marmosets. This behavioral profile occurred regardless of any concomitant change or correlation with cortisol. Therefore, the high fat/sugar food was more prone to be overly consumed by the marmosets, to induce a CPP response and to lead to anxiety-related behavior in its absence. PMID:25447426

  1. Physiological Roles of the Dual Phosphate Transporter Systems in Low and High Phosphate Conditions and in Capsule Maintenance of Streptococcus pneumoniae D39.

    PubMed

    Zheng, Jiaqi J; Sinha, Dhriti; Wayne, Kyle J; Winkler, Malcolm E

    2016-01-01

    Unlike most bacteria, Streptococcus pneumoniae (pneumococcus) has two evolutionarily distinct ABC transporters (Pst1 and Pst2) for inorganic phosphate (Pi) uptake. The genes encoding a two-component regulator (PnpRS) are located immediately upstream of the pst1 operon. Both the pst1 and pst2 operons encode putative PhoU-family regulators (PhoU1 and PhoU2) at their ends. This study addresses why S. pneumoniae contains dual Pi uptake systems and the regulation and contribution of the Pst1 and Pst2 systems in conditions of high (mM) Pi amount and low (μM) Pi amount. We show that in unencapsulated mutants, both pst1 and pst2 can be deleted, and Pi is taken up by a third Na(+)/Pi co-transporter, designated as NptA. In contrast, either pst1 or pst2 is unexpectedly required for the growth of capsule producing strains. We used a combination of mutational analysis, transcript level determinations by qRT-PCR and RNA-Seq, assays for cellular PnpR~P amounts by SDS-PAGE, and pulse-Pi uptake experiments to study the regulation of Pi uptake. In high Pi medium, PhoU2 serves as the master negative regulator of Pst2 transporter function and PnpR~P levels (post-transcriptionally). ΔphoU2 mutants have high PnpR~P levels and induction of the pst1 operon, poor growth, and sensitivity to antibiotics, possibly due to high Pi accumulation. In low Pi medium, Pst2 is still active, but PnpR~P amount and pst1 operon levels increase. Together, these results support a model in which pneumococcus maintains high Pi transport in high and low Pi conditions that is required for optimal capsule biosynthesis. PMID:27379215

  2. Physiological Roles of the Dual Phosphate Transporter Systems in Low and High Phosphate Conditions and in Capsule Maintenance of Streptococcus pneumoniae D39

    PubMed Central

    Zheng, Jiaqi J.; Sinha, Dhriti; Wayne, Kyle J.; Winkler, Malcolm E.

    2016-01-01

    Unlike most bacteria, Streptococcus pneumoniae (pneumococcus) has two evolutionarily distinct ABC transporters (Pst1 and Pst2) for inorganic phosphate (Pi) uptake. The genes encoding a two-component regulator (PnpRS) are located immediately upstream of the pst1 operon. Both the pst1 and pst2 operons encode putative PhoU-family regulators (PhoU1 and PhoU2) at their ends. This study addresses why S. pneumoniae contains dual Pi uptake systems and the regulation and contribution of the Pst1 and Pst2 systems in conditions of high (mM) Pi amount and low (μM) Pi amount. We show that in unencapsulated mutants, both pst1 and pst2 can be deleted, and Pi is taken up by a third Na+/Pi co-transporter, designated as NptA. In contrast, either pst1 or pst2 is unexpectedly required for the growth of capsule producing strains. We used a combination of mutational analysis, transcript level determinations by qRT-PCR and RNA-Seq, assays for cellular PnpR~P amounts by SDS-PAGE, and pulse-Pi uptake experiments to study the regulation of Pi uptake. In high Pi medium, PhoU2 serves as the master negative regulator of Pst2 transporter function and PnpR~P levels (post-transcriptionally). ΔphoU2 mutants have high PnpR~P levels and induction of the pst1 operon, poor growth, and sensitivity to antibiotics, possibly due to high Pi accumulation. In low Pi medium, Pst2 is still active, but PnpR~P amount and pst1 operon levels increase. Together, these results support a model in which pneumococcus maintains high Pi transport in high and low Pi conditions that is required for optimal capsule biosynthesis. PMID:27379215

  3. Performance degradation and altered cerebral activation during dual performance: Evidence for a bottom-up attentional system

    PubMed Central

    Gazes, Yunglin; Rakitin, Brian C.; Steffener, Jason; Habeck, Christian; Butterfield, Brady; Ghez, Claude; Stern, Yaakov

    2012-01-01

    Subjects performed a continuous tracking concurrently with an intermittent visual detection task to investigate the existence of competition for a capacity-limited stage (a bottleneck stage). Both perceptual and response-related processes between the two tasks were examined behaviorally and the changes in brain activity during dual-tasking relative to single-task were also assessed. Tracking error and joystick speed were analyzed for changes that were time-locked to visual detection stimuli. The associated brain activations were examined with functional magnetic resonance imaging (fMRI). These were analyzed using mixed block and event-related models to tease apart sustained neural activity and activations associated with individual events. Increased tracking error and decreased joystick speed were observed relative to the target stimuli in the dual-task condition only, which supports the existence of a bottleneck stage in response-related processes. Neuroimaging data show decreased activation to target relative to non-target stimuli in the dual-task condition in the left primary motor and somatosensory cortices controlling right-hand tracking, consistent with the tracking interference observed in behavioral data. Furthermore, the ventral attention system, rather than the dorsal attention system, was found to mediate task coordination between tracking and visual detection. PMID:20188768

  4. Development of a conditioning system for the dual-purpose transport and storage cask for spent nuclear fuel from decommissioned Russian submarines

    SciTech Connect

    Dyer, R.S.; Barnes, E.; Snipes, R.L.; Guskov, V.; Makarchuk, T.

    2007-07-01

    Russia, stores large quantities of spent nuclear fuel (SNF) from submarine and ice-breaker nuclear powered naval vessels. This high-level radioactive material presents a significant threat to the Arctic and marine environments. Much of the SNF from decommissioned Russian nuclear submarines is stored either onboard the submarines or in floating storage vessels in Northwest and Far East Russia. Some of the SNF is damaged, stored in an unstable condition, or of a type that cannot currently be reprocessed. In many cases, the existing Russian transport infrastructure and reprocessing facilities cannot meet the requirements for moving and reprocessing all of this fuel from remote locations. Additional transport and storage options are required. Some of the existing storage facilities being used in Russia do not meet health and safety and physical security requirements. The U.S. has assisted Russia in the development of a new dual-purpose metal-concrete transport and storage cask (TUK-108/1) for their military SNF and assisted them in building several new facilities for off-loading submarine SNF and storing these TUK-108/1 casks. These efforts have reduced the technical, ecological, and security challenges for removal, handling, interim storage, and shipment of this submarine fuel. Currently, Russian licensing limits the storage period of the TUK-108/1 casks to no more than two years before the fuel must be shipped for reprocessing. In order to extend this licensed storage period, a system is required to condition the casks by removing residual water and creating an inert storage environment by backfilling the internal canisters with a noble gas such as argon. The U.S. has assisted Russia in the development of a mobile cask conditioning system for the TUK-108/1 cask. This new conditioning system allows the TUK 108/1 casks to be stored for up to five years after which the license may be considered for renewal for an additional five years or the fuel will be shipped to

  5. Assessment of conditioning-specific movement tasks and physical fitness measures in talent identified under 16-year-old rugby union players.

    PubMed

    Parsonage, Joanna R; Williams, Rhodri S; Rainer, Paul; McKeown, Ian; Williams, Morgan D

    2014-06-01

    Preparedness to train was assessed using a battery of conditioning-specific movement tasks (CSMTs) on a group of talent identified rugby union players (n = 156; age = 15 ± 7 years; stature = 176 ± 7 cm; and mass = 74 ± 14 kg). In addition to explore the link between movement competency and performance, a series of standard fitness tests was conducted. Overall the group's CSMTs competency ratings were low, but task dependent. The proportion of competent players ranged from 14% for a single leg squat to 70% for a double to single leg landing. Players were subsequently grouped based on their CSMTs ratings using cluster analysis. This analysis classified players on features of the CSMT battery that distinguished between groups rather than an arbitrary score. Fitness test scores were then compared between the 3 groups identified. The "general low competency" group jumped 9.1 cm lower (p = 0.0218), sprinted slower across 10, 20 and 40 m (range, p = 0.0126-0.0018) and covered 389 m less (p = 0.0105) Yo-Yo intermittent recovery level 1 distance compared with the "squat competent group." In summary, at this important time before academy selection, most players could not competently perform the CSMTs that underpin rugby conditioning and may not be prepared for the transition into the "training to compete" stage of the suggested long-term athlete development model. For this sample of players, the athlete development process may therefore be unnecessarily inhibited. Moreover, our observations that competency in some CSMTs may explain better running and jumping performances in some players suggest that a focus on monitoring and addressing movement competencies during the training to train stage of player development should be considered.

  6. Single-task fMRI overlap predicts concurrent multitasking interference.

    PubMed

    Nijboer, Menno; Borst, Jelmer; van Rijn, Hedderik; Taatgen, Niels

    2014-10-15

    There is no consensus regarding the origin of behavioral interference that occurs during concurrent multitasking. Some evidence points toward a multitasking locus in the brain, while other results imply that interference is the consequence of task interactions in several brain regions. To investigate this issue, we conducted a functional MRI (fMRI) study consisting of three component tasks, which were performed both separately and in combination. The results indicated that no specific multitasking area exists. Instead, different patterns of activation across conditions could be explained by assuming that the interference is a result of task interactions. Additionally, similarity in single-task activation patterns correlated with a decrease in accuracy during dual-task conditions. Taken together, these results support the view that multitasking interference is not due to a bottleneck in a single "multitasking" brain region, but is a result of interactions between concurrently running processes.

  7. Stroop proactive control and task conflict are modulated by concurrent working memory load.

    PubMed

    Kalanthroff, Eyal; Avnit, Amir; Henik, Avishai; Davelaar, Eddy J; Usher, Marius

    2015-06-01

    Performance on the Stroop task reflects two types of conflict-informational (between the incongruent word and font color) and task (between the contextually relevant color-naming task and the irrelevant, but automatic, word-reading task). According to the dual mechanisms of control theory (DMC; Braver, 2012), variability in Stroop performance can result from variability in the deployment of a proactive task-demand control mechanism. Previous research has shown that when proactive control (PC) is diminished, both increased Stroop interference and a reversed Stroop facilitation (RF) are observed. Although the current DMC model accounts for the former effect, it does not predict the observed RF, which is considered to be behavioral evidence for task conflict in the Stroop task. Here we expanded the DMC model to account for Stroop RF. Assuming that a concurrent working memory (WM) task reduces PC, we predicted both increased interference and an RF. Nineteen participants performed a standard Stroop task combined with a concurrent n-back task, which was aimed at reducing available WM resources, and thus overloading PC. Although the results indicated common Stroop interference and facilitation in the low-load condition (zero-back), in the high-load condition (two-back), both increased Stroop interference and RF were observed, consistent with the model's prediction. These findings indicate that PC is modulated by concurrent WM load and serves as a common control mechanism for both informational and task Stroop conflicts.

  8. Grid Task Execution

    NASA Technical Reports Server (NTRS)

    Hu, Chaumin

    2007-01-01

    IPG Execution Service is a framework that reliably executes complex jobs on a computational grid, and is part of the IPG service architecture designed to support location-independent computing. The new grid service enables users to describe the platform on which they need a job to run, which allows the service to locate the desired platform, configure it for the required application, and execute the job. After a job is submitted, users can monitor it through periodic notifications, or through queries. Each job consists of a set of tasks that performs actions such as executing applications and managing data. Each task is executed based on a starting condition that is an expression of the states of other tasks. This formulation allows tasks to be executed in parallel, and also allows a user to specify tasks to execute when other tasks succeed, fail, or are canceled. The two core components of the Execution Service are the Task Database, which stores tasks that have been submitted for execution, and the Task Manager, which executes tasks in the proper order, based on the user-specified starting conditions, and avoids overloading local and remote resources while executing tasks.

  9. Task-Based Learning: The Interaction between Tasks and Learners.

    ERIC Educational Resources Information Center

    Murphy, Jacky

    2003-01-01

    Investigates the relationship between tasks and learners in task-based learning. Findings suggest that manipulation of task characteristics and conditions may not achieve the intended pedagogic outcomes, and that new ways are needed to focus learners' attention of form without sacrificing the meaning-driven principles of task-based learning.…

  10. People have the power: priority of socially relevant stimuli in a change detection task.

    PubMed

    Bracco, Fabrizio; Chiorri, Carlo

    2009-02-01

    Change detection performance is influenced by a number of factors, among which is the informativeness of targets. It has not been clarified, yet, whether the highly informative regions have a processing priority as a result of resource deployment from other tasks or whether it results from a better resource management. In this paper, we adopted a change detection paradigm in which thirty participants were randomly assigned to two groups: single (change detection task) and dual task [change detection and a simplified version of the Paced Auditory Serial Oppository Task (PASOT, Gow and Deary in J Clin Exp Neuropsychol 26:723-736, 2004), which implies a verbal effort]. Stimulus informativeness was defined as social relevance, that is, changing targets were people (high relevance) versus objects (low relevance), all other aspects (i.e., salience and position in the scene) kept constant. As hypothesized, data analyses showed a significant main effect of social relevance and task condition, i.e., better change detection performance and lower change detection times for people versus objects and for single than for dual task condition. Interestingly, the PASOT accuracy remained stable across the person versus object trials, thus implying that the better performance with socially relevant targets could not be explained by a resources withdrawal from the secondary task.

  11. Qualitative attentional changes with age in doing two tasks at once.

    PubMed

    Maquestiaux, François

    2016-02-01

    Does practice reduce, or even eliminate, aging effects on the attentional limitations responsible for dual-task interference? The studies reviewed in this article show that age differences reliably persist after extensive practice. Strikingly, dual-task interference remains larger among older adults even in training conditions that allow them to achieve single-task performance as fast as younger adults. These findings demonstrate that age deficits in attentional functioning are robust. Advancing age also can be accompanied by improvements in cognitive functioning, such as in the ability to access the lexicon without attention (i.e., automatically), due to lifelong experience with word reading. Future research needs to establish whether age deficits in central attention are due to structural changes that are irreversible or reversible to some extent. PMID:26106060

  12. Re-examination of amphetamine-induced conditioned suppression of tastant intake in rats: the task-dependent drug effects hypothesis.

    PubMed

    Huang, Andrew Chih Wei; Hsiao, Sigmund

    2008-12-01

    This study reexamined Grigson's reward comparison hypothesis (1997), which claimed to have resolved the paradox of addictive, rewarding drugs manifesting an aversive effect in the conditioned taste aversion (CTA) paradigm. Here, the authors compared the conditioned suppression effects of lithium chloride (LiCl) and amphetamine in a series of three experiments. In Experiment 1, the concentrations of saccharin solution (conditioned stimulus [CS]) and the doses of amphetamine or LiCl (unconditioned stimulus [US]) were manipulated. In Experiment 2, the effects of employing backward versus forward pairings of the CS and US were compared. Finally, in Experiment 3, the additivity of amphetamine's reward property and LiCl's aversive property was examined. The results of these experiments, respectively, indicated that: (1) manipulating saccharin solution concentrations does not distinguish the suppression effect caused by rewarding or aversive effects when amphetamine or LiCl served as the US; (2) both backward and forward pairings produced suppression of saccharin solution intake regardless of whether amphetamine or LiCl was used as the US; and (3) combining amphetamine and LiCl did not diminish the suppression effect, as would be expected if they had opposing mechanisms for the effects; instead, an additive effect occurred. Taken together, these results suggest that the drug of abuse amphetamine and the emetic drug LiCl both possess aversive properties in the CTA paradigm. No rewarding effects of amphetamine were detected in our experimental data. In all, our results do not support the Grigson's reward comparison hypothesis (1997) and a new "task-dependent drug effects hypothesis" is proposed.

  13. Concurrent working memory task decreases the Stroop interference effect as indexed by the decreased theta oscillations.

    PubMed

    Zhao, Y; Tang, D; Hu, L; Zhang, L; Hitchman, G; Wang, L; Chen, A

    2014-03-14

    Working memory (WM) tasks may increase or decrease the interference effect of concurrently performed cognitive control tasks. However, the neural oscillatory correlates of this modulation effect of WM on the Stroop task are still largely unknown. In the present study, behavioral and electroencephalographic (EEG) data were recorded from 32 healthy participants during their performance of the single Stroop task and the same task with a concurrent WM task. We observed that the Stroop interference effect represented in both response times (RTs) and theta-band event-related spectral perturbation (ERSP) magnitude reduced under the dual-task condition compared with the single-task condition. The reduction of interference in theta-band ERSP was further positively correlated with interference reduction in RTs, and was mainly explained by the source in the left middle frontal gyrus. In conclusion, the present study suggests that the effect of concurrent WM tasks on the reduction of the Stroop interference effect can be indexed by EEG oscillations in theta-band rhythm in the centro-frontal regions and this modulation was mediated by the reduced cognitive control under the concurrent WM task.

  14. Executive Resources and Item-Context Binding: Exploring the Influence of Concurrent Inhibition, Updating, and Shifting Tasks on Context Memory

    PubMed Central

    Nieznański, Marek; Obidziński, Michał; Zyskowska, Emilia; Niedziałkowska, Daria

    2015-01-01

    Previous research has demonstrated that context memory performance decreases as a result of cognitive load. However, the role of specific executive resources availability has not been specified yet. In a dual-task experiment, participants performed three kinds of concurrent task engaging: inhibition, updating, or shifting operations. In comparison with a no-load single-task condition, a significant decrease in item and context memory was observed, regardless of the kind of executive task. When executive load conditions were compared with non-specific cognitive load conditions, a significant interference effect was observed in the case of the inhibition task. The inhibition process appears to be an aspect of executive control, which relies on the same resource as item-context binding does, especially when binding refers to associations retrieved from long-term memory. PMID:26435761

  15. Flexible connectivity in the aging brain revealed by task modulations.

    PubMed

    Geerligs, Linda; Saliasi, Emi; Renken, Remco J; Maurits, Natasha M; Lorist, Monicque M

    2014-08-01

    Recent studies have shown that aging has a large impact on connectivity within and between functional networks. An open question is whether elderly still have the flexibility to adapt functional network connectivity (FNC) to the demands of the task at hand. To study this, we collected fMRI data in younger and older participants during resting state, a selective attention (SA) task and an n-back working memory task with varying levels of difficulty. Spatial independent component (IC) analysis was used to identify functional networks over all participants and all conditions. Dual regression was used to obtain participant and task specific time-courses per IC. Subsequently, functional connectivity was computed between all ICs in each of the tasks. Based on these functional connectivity matrices, a scaled version of the eigenvector centrality (SEC) was used to measure the total influence of each IC in the complete graph of ICs. The results demonstrated that elderly remain able to adapt FNC to task demands. However, there was an age-related shift in the impetus for FNC change. Older participants showed the maximal change in SEC patterns between resting state and the SA task. Young participants, showed the largest shift in SEC patterns between the less demanding SA task and the more demanding 2-back task. Our results suggest that increased FNC changes from resting state to low demanding tasks in elderly reflect recruitment of additional resources, compared with young adults. The lack of change between the low and high demanding tasks suggests that elderly reach a resource ceiling. PMID:24382835

  16. Flexible connectivity in the aging brain revealed by task modulations.

    PubMed

    Geerligs, Linda; Saliasi, Emi; Renken, Remco J; Maurits, Natasha M; Lorist, Monicque M

    2014-08-01

    Recent studies have shown that aging has a large impact on connectivity within and between functional networks. An open question is whether elderly still have the flexibility to adapt functional network connectivity (FNC) to the demands of the task at hand. To study this, we collected fMRI data in younger and older participants during resting state, a selective attention (SA) task and an n-back working memory task with varying levels of difficulty. Spatial independent component (IC) analysis was used to identify functional networks over all participants and all conditions. Dual regression was used to obtain participant and task specific time-courses per IC. Subsequently, functional connectivity was computed between all ICs in each of the tasks. Based on these functional connectivity matrices, a scaled version of the eigenvector centrality (SEC) was used to measure the total influence of each IC in the complete graph of ICs. The results demonstrated that elderly remain able to adapt FNC to task demands. However, there was an age-related shift in the impetus for FNC change. Older participants showed the maximal change in SEC patterns between resting state and the SA task. Young participants, showed the largest shift in SEC patterns between the less demanding SA task and the more demanding 2-back task. Our results suggest that increased FNC changes from resting state to low demanding tasks in elderly reflect recruitment of additional resources, compared with young adults. The lack of change between the low and high demanding tasks suggests that elderly reach a resource ceiling.

  17. Dissociating proactive and reactive control in the Stroop task.

    PubMed

    Gonthier, Corentin; Braver, Todd S; Bugg, Julie M

    2016-07-01

    The Dual Mechanisms of Control framework posits the existence of two distinct control mechanisms, proactive and reactive, which may operate independently. However, this independence has been difficult to study with most experimental paradigms. The Stroop task may provide a useful way of assessing the independence of control mechanisms because the task elicits two types of proportion congruency effects, list-wide and item-specific, thought to reflect proactive and reactive control respectively. The present research tested whether these two proportion congruency effects can be used to dissociate proactive and reactive control. In 2 separate participant samples, we demonstrate that list-wide and item-specific proportion congruency effects are stable, exist in the same participants, and appear in different task conditions. Moreover, we identify two distinct behavioral signatures, the congruency cost and the transfer cost, which doubly dissociate the two effects. Together, the results are consistent with the view that proactive and reactive control reflect independent mechanisms. PMID:26861210

  18. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record PMID:27295467

  19. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record

  20. Paradoxical mineralocorticoid receptor-mediated effect in fear memory encoding and expression of rats submitted to an olfactory fear conditioning task.

    PubMed

    Souza, Rimenez R; Dal Bó, Silvia; de Kloet, E Ronald; Oitzl, Melly S; Carobrez, Antonio P

    2014-04-01

    There is general agreement that the substantial modification in memory and motivational states exerted by corticosteroids after a traumatic experience is mediated in complementary manner by the mineralocorticoid (MR) and glucocorticoid (GR) receptors. Here we tested the hypothesis that pharmacological manipulation of MR activity would affect behavioral strategy and information storage in an olfactory fear conditioning (OFC) task. Male Wistar rats were submitted to the OFC with different training intensities. We observed that following high intensity OFC acquisition, a set of defensive coping strategies, which includes avoidance and risk assessment behaviors, was elicited when subjects were exposed to the conditioned stimulus (CS) 48 h later. In addition, following either OFC acquisition or retrieval (CS-I test) a profound corticosterone secretion was also detected. Systemic administration of the MR antagonist spironolactone altered the behavioral coping style irrespective the antagonist was administered 60 min prior to the acquisition or before the retrieval session. Surprisingly, the MR agonist fludrocortisone given 60 min prior to acquisition or retrieval of OFC had similar effects as the antagonist. In addition, post-training administration of fludrocortisone, following a weak training procedure, facilitated the consolidation of OFC. Fludrocortisone rather than spironolactone reduced serum corticosterone levels, suggesting that, at least in part, the effects of the MR agonist may derive from additional GR-mediated HPA-axis suppression. In conclusion, the present study suggests the involvement of the MR in the fine-tuning of behavioral adaptation necessary for optimal information storage and expression, as revealed by the marked alterations in the risk assessment behavior.

  1. Dissociable effects of AMPA-induced lesions of the vertical limb diagonal band of Broca on performance of the 5-choice serial reaction time task and on acquisition of a conditional visual discrimination.

    PubMed

    Muir, J L; Bussey, T J; Everitt, B J; Robbins, T W

    1996-12-01

    The aim of the present study was to investigate the role of the cholinergic innervation of the cingulate cortex in visual attentional function and acquisition of a visual conditional discrimination task. Following AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) lesions of the vertical limb diagonal band of Broca (VDB) which provides the main cholinergic projection to cingulate cortex, animals were not significantly impaired on the 5-choice serial reaction time task. This task, which provides a continuous performance test of visual attention, has previously been shown to be sensitive to AMPA lesions of the nucleus basalis magnocellularis (nbM). In contrast to the results obtained for visual attentional function, lesions of the VDB did significantly affect the acquisition of a visual conditional discrimination. While showing a significant facilitation in the early learning stage of acquiring this task animals with lesions of the VDB were significantly impaired during the late stages of learning this task. This late learning deficit was not the result of the animals being unable to learn the task due to the presence of the lesion throughout task acquisition as the results of a second experiment revealed that when animals were pre-trained to 70% accuracy on the task and then lesioned, the impairment in late learning was still apparent. In light of the results presented in the accompanying paper (Bussey et al., Behav. Brain Res., 1996), these results suggest that the early learning effects may be due to cholinergic denervation of the anterior cingulate cortex while the late learning effects may be due to denervation of the posterior cingulate cortex. Taken together with previous work indicating a role for the nbM cholinergic system in visual attentional function, these results suggest a role for the cholinergic innervation of the cingulate cortex in conditional learning but not for continuous attentional performance.

  2. Brief report: manipulation of task difficulty in inhibitory control tasks.

    PubMed

    Lindqvist, Sofia; Thorell, Lisa B

    2009-01-01

    The present study investigated how task difficulty can be manipulated in inhibitory control tasks. Tasks from three widely used task paradigms - a Go/No-Go task, a Stop-Signal task,and a Flanker task - were manipulated on two parameters each (Go/No-Go task: interstimulus interval, prepotency. Stop-signal task: stop-signal-delay, prepotency. Flanker task:number of distractors, size of target stimulus). Participants were 86 children (age 4-6) from a population-based sample. The results showed no significant effects on the Go/No-Go task but both main and interaction effects on the Stop-Signal task and the Flanker task. Together, these findings indicate that task difficulty can be successfully manipulated in inhibitory control tasks. However, the interactive rather than additive effects on performance suggest that the level of one parameter only has the desired effect under certain conditions. This new information about how to manipulate task difficulty is important when adapting tasks for use with children of different ages, as well as when designing training programs for improving inhibitory control among children with ADHD. PMID:18608218

  3. Task breakdown

    NASA Technical Reports Server (NTRS)

    Pavlich, Jane

    1990-01-01

    The topics concerning the Center for Space Construction (CSC) space construction breakdown structure are presented in viewgraph form. It is concluded that four components describe a task -- effecting, information gathering, analysis, and regulation; uncertainties effect the relative amount of information gathering and analysis that occurs; and that task timing requirements drive the 'location in time' of cognition.

  4. Methodological issues in product evaluation: the influence of testing environment and task scenario.

    PubMed

    Sauer, Juergen; Sonderegger, Andreas

    2011-03-01

    This article examines the utility of two commonly used approaches in the evaluation of interactive consumer products: lab-based testing and single task scenarios. These are compared to two more complex and resource-demanding approaches (field-based testing and dual task scenarios) with regard to the test results they produce. An experiment with N = 80 users was carried out, employing a 2 (laboratory vs. field) by 2 (single task vs. dual task scenario) by 2 (on-product information: present vs. absent) between-subjects design. On-product information (advising users to save water and electricity during kettle usage) represented the intervention, of which the effects on user behaviour were compared under the different experimental conditions. The main finding was that the impact of on-product information on user behaviour was strongest in the lab-based testing environment using a single task scenario (i.e., most economical testing condition), compared to the three other experimental conditions. The work found similar effects for self-report measures. The findings of the study point to the risk that the effects of system redesign on user behaviour may be overestimated if low-fidelity testing approaches are employed. The relevance of these findings for other application areas is also discussed (e.g., design of warnings).

  5. Defining conditions where long-term glucocorticoid treatment has an acceptably low level of harm to facilitate implementation of existing recommendations: viewpoints from an EULAR task force.

    PubMed

    Strehl, Cindy; Bijlsma, Johannes W J; de Wit, Maarten; Boers, Maarten; Caeyers, Nele; Cutolo, Maurizio; Dasgupta, Bhaskar; Dixon, William G; Geenen, Rinie; Huizinga, Tom W J; Kent, Alison; de Thurah, Annette Ladefoged; Listing, Joachim; Mariette, Xavier; Ray, David W; Scherer, Hans U; Seror, Raphaèle; Spies, Cornelia M; Tarp, Simon; Wiek, Dieter; Winthrop, Kevin L; Buttgereit, Frank

    2016-06-01

    There is convincing evidence for the known and unambiguously accepted beneficial effects of glucocorticoids at low dosages. However, the implementation of existing recommendations and guidelines on the management of glucocorticoid therapy in rheumatic diseases is lagging behind. As a first step to improve implementation, we aimed at defining conditions under which long-term glucocorticoid therapy may have an acceptably low level of harm. A multidisciplinary European League Against Rheumatism task force group of experts including patients with rheumatic diseases was assembled. After a systematic literature search, breakout groups critically reviewed the evidence on the four most worrisome adverse effects of glucocorticoid therapy (osteoporosis, hyperglycaemia/diabetes mellitus, cardiovascular diseases and infections) and presented their results to the other group members following a structured questionnaire for final discussion and consensus finding. Robust evidence on the risk of harm of long-term glucocorticoid therapy was often lacking since relevant study results were often either missing, contradictory or carried a high risk of bias. The group agreed that the risk of harm is low for the majority of patients at long-term dosages of ≤5 mg prednisone equivalent per day, whereas at dosages of >10 mg/day the risk of harm is elevated. At dosages between >5 and ≤10 mg/day, patient-specific characteristics (protective and risk factors) determine the risk of harm. The level of harm of glucocorticoids depends on both dose and patient-specific parameters. General and glucocorticoid-associated risk factors and protective factors such as a healthy lifestyle should be taken into account when evaluating the actual and future risk. PMID:26933146

  6. Tracking performance under time sharing conditions with a digit processing task: A feedback control theory analysis. [attention sharing effect on operator performance

    NASA Technical Reports Server (NTRS)

    Gopher, D.; Wickens, C. D.

    1975-01-01

    A one dimensional compensatory tracking task and a digit processing reaction time task were combined in a three phase experiment designed to investigate tracking performance in time sharing. Adaptive techniques, elaborate feedback devices, and on line standardization procedures were used to adjust task difficulty to the ability of each individual subject and manipulate time sharing demands. Feedback control analysis techniques were employed in the description of tracking performance. The experimental results show that when the dynamics of a system are constrained, in such a manner that man machine system stability is no longer a major concern of the operator, he tends to adopt a first order control describing function, even with tracking systems of higher order. Attention diversion to a concurrent task leads to an increase in remnant level, or nonlinear power. This decrease in linearity is reflected both in the output magnitude spectra of the subjects, and in the linear fit of the amplitude ratio functions.

  7. Effects of transient global ischaemia on freezing behaviour and activity in a context-dependent fear conditioning task--implications for memory investigations.

    PubMed

    Henrich-Noack, Petra; Krautwald, Karla; Reymann, Klaus G; Wetzel, Wolfram

    2011-07-15

    , measuring duration of freezing and the activity score seems to be not applicable for quantitative comparisons of memory deficits after 2VO in gerbils in a context-dependent fear conditioning task. Our results indicate, however, that initiation of freezing (number of freezing bouts) may be a more suitable parameter comparing gerbils with and without CA1 damage. PMID:21515344

  8. Effects of transient global ischaemia on freezing behaviour and activity in a context-dependent fear conditioning task--implications for memory investigations.

    PubMed

    Henrich-Noack, Petra; Krautwald, Karla; Reymann, Klaus G; Wetzel, Wolfram

    2011-07-15

    , measuring duration of freezing and the activity score seems to be not applicable for quantitative comparisons of memory deficits after 2VO in gerbils in a context-dependent fear conditioning task. Our results indicate, however, that initiation of freezing (number of freezing bouts) may be a more suitable parameter comparing gerbils with and without CA1 damage.

  9. Conflict monitoring and adjustment in the task-switching paradigm under different memory load conditions: an ERP/sLORETA analysis.

    PubMed

    Deng, Yuqin; Wang, Yan; Ding, Xiaoqian; Tang, Yi-Yuan

    2015-02-11

    The aim of the present study was to examine electrophysiological and behavioral changes caused by different memory loads in a task-switching paradigm. A total of 31 healthy individuals were subjected to a task, in which the stimulus-response reversal paradigm was combined with the task-switching paradigm. The event-related potentials were recorded and the N2 component, an index of conflict processing, was measured. In addition, the neural sources of N2 were further analyzed by standardized low-resolution brain electromagnetic tomography. The event-related potential results showed that high memory load triggered a higher N2 mean amplitude. Moreover, the standardized low-resolution brain electromagnetic tomography data showed that high memory load caused an increase in current densities at the anterior cingulate cortex and the prefrontal cortex in the task-switching paradigm. In summary, our findings provide electrophysiological evidence to interpret possible influences of memory loads on conflict monitoring and modulation during the task switching. These results imply that the working memory load overrules the influence of task-switching performance on the intensification of cognitive control.

  10. Conflict monitoring and adjustment in the task-switching paradigm under different memory load conditions: an ERP/sLORETA analysis.

    PubMed

    Deng, Yuqin; Wang, Yan; Ding, Xiaoqian; Tang, Yi-Yuan

    2015-02-11

    The aim of the present study was to examine electrophysiological and behavioral changes caused by different memory loads in a task-switching paradigm. A total of 31 healthy individuals were subjected to a task, in which the stimulus-response reversal paradigm was combined with the task-switching paradigm. The event-related potentials were recorded and the N2 component, an index of conflict processing, was measured. In addition, the neural sources of N2 were further analyzed by standardized low-resolution brain electromagnetic tomography. The event-related potential results showed that high memory load triggered a higher N2 mean amplitude. Moreover, the standardized low-resolution brain electromagnetic tomography data showed that high memory load caused an increase in current densities at the anterior cingulate cortex and the prefrontal cortex in the task-switching paradigm. In summary, our findings provide electrophysiological evidence to interpret possible influences of memory loads on conflict monitoring and modulation during the task switching. These results imply that the working memory load overrules the influence of task-switching performance on the intensification of cognitive control. PMID:25569792

  11. Word Fluency: A Task Analysis.

    ERIC Educational Resources Information Center

    Laine, Matti

    It is suggested that models of human problem solving are useful in the analysis of word fluency (WF) test performance. In problem-solving terms, WF tasks would require the subject to define and clarify the conditions of the task (task acquisition), select and employ appropriate strategies, and monitor one's performance. In modern neuropsychology,…

  12. Prefrontal cortex activity during motor tasks with additional mental load requiring attentional demand: a near-infrared spectroscopy study.

    PubMed

    Mandrick, Kevin; Derosiere, Gérard; Dray, Gérard; Coulon, Denis; Micallef, Jean-Paul; Perrey, Stéphane

    2013-07-01

    Functional near-infrared spectroscopy (fNIRS) is suitable for investigating cerebral oxygenation changes during motor and/or mental tasks. In the present study, we investigated how an additional mental load during a motor task at two submaximal loadings affects the fNIRS-measured brain activation over the right prefrontal cortex (PFC). Fifteen healthy males performed isometric grasping contractions at 15% and 30% of the maximal voluntary contraction (MVC) with or without an additional mental (i.e., arithmetic) task. Mental performance, force variability, fNIRS and subjective perception responses were measured in each condition. The performance of the mental task decreased significantly while the force variability increased significantly at 30% MVC as compared to 15% MVC, suggesting that performance of dual-task required more attentional resources. PFC activity increased significantly as the effort increased from 15% to 30% MVC (p<.001). Although a larger change in the deoxyhemoglobin was observed in dual-task conditions (p=.051), PFC activity did not change significantly as compared to the motor tasks alone. In summary, participants were unable to invest more attention and effort in performing the more difficult levels in order to maintain adequate mental performance.

  13. Prefrontal cortex activity during motor tasks with additional mental load requiring attentional demand: a near-infrared spectroscopy study.

    PubMed

    Mandrick, Kevin; Derosiere, Gérard; Dray, Gérard; Coulon, Denis; Micallef, Jean-Paul; Perrey, Stéphane

    2013-07-01

    Functional near-infrared spectroscopy (fNIRS) is suitable for investigating cerebral oxygenation changes during motor and/or mental tasks. In the present study, we investigated how an additional mental load during a motor task at two submaximal loadings affects the fNIRS-measured brain activation over the right prefrontal cortex (PFC). Fifteen healthy males performed isometric grasping contractions at 15% and 30% of the maximal voluntary contraction (MVC) with or without an additional mental (i.e., arithmetic) task. Mental performance, force variability, fNIRS and subjective perception responses were measured in each condition. The performance of the mental task decreased significantly while the force variability increased significantly at 30% MVC as compared to 15% MVC, suggesting that performance of dual-task required more attentional resources. PFC activity increased significantly as the effort increased from 15% to 30% MVC (p<.001). Although a larger change in the deoxyhemoglobin was observed in dual-task conditions (p=.051), PFC activity did not change significantly as compared to the motor tasks alone. In summary, participants were unable to invest more attention and effort in performing the more difficult levels in order to maintain adequate mental performance. PMID:23665138

  14. FNAS/summer faculty fellowship research continuation program. Task 6: Integrated model development for liquid fueled rocket propulsion systems. Task 9: Aspects of model-based rocket engine condition monitoring and control

    NASA Technical Reports Server (NTRS)

    Santi, L. Michael; Helmicki, Arthur J.

    1993-01-01

    The objective of Phase I of this research effort was to develop an advanced mathematical-empirical model of SSME steady-state performance. Task 6 of Phase I is to develop component specific modification strategy for baseline case influence coefficient matrices. This report describes the background of SSME performance characteristics and provides a description of the control variable basis of three different gains models. The procedure used to establish influence coefficients for each of these three models is also described. Gains model analysis results are compared to Rocketdyne's power balance model (PBM).

  15. Walking while Performing Working Memory Tasks Changes the Prefrontal Cortex Hemodynamic Activations and Gait Kinematics

    PubMed Central

    Lin, Ming-I B.; Lin, Kuan-Hung

    2016-01-01

    Background: Increasing evidence suggests that walking while performing a concurrent task negatively influences gait performance. However, it remains unclear how higher-level cognitive processes and coordination of limb movements are altered in challenging walking environments. This study investigated the influence of cognitive task complexity and walking road condition on the neutral correlates of executive function and postural control in dual-task walking. Methods: Twenty-four healthy young adults completed a series of overground walks with three walking road conditions (wide, narrow, with obstacles) with and without the concurrent n-back working memory tasks of two complexity levels (1-back and 3-back). Prefrontal brain activation was assessed by functional near-infrared spectroscopy. A three-dimensional motion analysis system was used simultaneously to measure gait performance and lower-extremity kinematics. Repeated measures analysis of variance were performed to examine the differences between the conditions. Results: In comparison with standing still, participants showed lower n-back task accuracy while walking, with the worst performance from the road with obstacles. Spatiotemporal gait parameters, lower-extremity joint movements, and the relative changes in oxygenated hemoglobin (HbO) concentration levels were all significantly different across the task complexity and walking path conditions. While dual-tasking participants were found to flex their hips and knees less, leading to a slower gait speed, longer stride time, shorter step length, and greater gait variability than during normal walking. For narrow-road walking, smaller ankle dorsiflexion and larger hip flexion were observed, along with a reduced gait speed. Obstacle negotiation was mainly characterized by increased gait variability than other conditions. HbO levels appeared to be lower during dual-task walking than normal walking. Compared to wide and obstacle conditions, walking on the narrow

  16. Questioning implicit motor learning as instantiated by the pursuit-tracking task.

    PubMed

    Lang, Alexandre; Gapenne, Olivier; Rovira, Katia

    2011-10-01

    The effect of concurrent visual feedback on the implicit learning of repeated segments in a task of pursuit tracking has been tested. Although this feedback makes it possible to regulate the positional error during the movement, it could also induce negative guidance effects. To test this hypothesis, a first set of participants (N=42) were assigned to two groups, which performed either the standard pursuit-tracking task based on the experimental paradigm of Pew ( 1974 ; group F-ST), or a task called "movement reproduction" in which the feedback was suppressed (group noF-ST). A second set of participants (N=26) performed in the same feedback condition groups but in a dual-task situation (F-DT and noF-DT; Experiment 2). The results appear to confirm our predictions since the participants in groups without feedback, contrary to those in groups with feedback, succeeded with practice in differentiating their performances as a function of the nature of the segments (repeated or nonrepeated) both in simple (Experiment 1) and in dual-task (Experiment 2) situations. These experiments indicate that the feedback in the pursuit-tracking task induces a guidance function potentially resulting in an easiness tracking that prevents the participants from learning the repetition.

  17. On the manipulability of dual cooperative robots

    NASA Technical Reports Server (NTRS)

    Chiacchio, P.; Chiaverini, S.; Sciavicco, L.; Siciliano, B.

    1989-01-01

    The definition of manipulability ellipsoids for dual robot systems is given. A suitable kineto-static formulation for dual cooperative robots is adopted which allows for a global task space description of external and internal forces, and relative velocities. The well known concepts of force and velocity manipulability ellipsoids for a single robot are formally extended and the contributions of the two single robots to the cooperative system ellipsoids are illustrated. Duality properties are discussed. A practical case study is developed.

  18. Response Activation in Overlapping Tasks and the Response-Selection Bottleneck

    ERIC Educational Resources Information Center

    Schubert, Torsten; Fischer, Rico; Stelzel, Christine

    2008-01-01

    The authors investigated the impact of response activation on dual-task performance by presenting a subliminal prime before the stimulus in Task 2 (S2) of a psychological refractory period (PRP) task. Congruence between prime and S2 modulated the reaction times in Task 2 at short stimulus onset asynchrony despite a PRP effect. This Task 2…

  19. The effects of participatory mode and task workload on the detection of dynamic system failures

    NASA Technical Reports Server (NTRS)

    Wickens, C. D.; Kessel, C.

    1977-01-01

    The ability of operators to detect step changes in the dynamics of control systems is investigated as a joint function of, (1) participatory mode: whether subjects are actively controlling those dynamics or are monitoring an autopilot controlling them, and (2) concurrent task workload. A theoretical analysis of detection in the two modes identifies factors that will favor detection in either mode. Three subjects detected system failures in either an autopilot or manual controlling mode, under single-task conditions and concurrently with a subcritical tracking task. Latency and accuracy of detection were assessed and related through a speed accuracy tradeoff representation. It was concluded that failure detection performance was better during manual control than during autopilot control, and that the extent of this superiority was enhanced as dual-task load increased. Ensemble averaging and multiple regression techniques were then employed to investigate the cues utilized by the subjects in making their detection decisions.

  20. Task Attention Facilitates Learning of Task-Irrelevant Stimuli

    PubMed Central

    Huang, Tsung-Ren; Watanabe, Takeo

    2012-01-01

    Attention plays a fundamental role in visual learning and memory. One highly established principle of visual attention is that the harder a central task is, the more attentional resources are used to perform the task and the smaller amount of attention is allocated to peripheral processing because of limited attention capacity. Here we show that this principle holds true in a dual-task setting but not in a paradigm of task-irrelevant perceptual learning. In Experiment 1, eight participants were asked to identify either bright or dim number targets at the screen center and to remember concurrently presented scene backgrounds. Their recognition performances for scenes paired with dim/hard targets were worse than those for scenes paired with bright/easy targets. In Experiment 2, eight participants were asked to identify either bright or dim letter targets at the screen center while a task-irrelevant coherent motion was concurrently presented in the background. After five days of training on letter identification, participants improved their motion sensitivity to the direction paired with hard/dim targets improved but not to the direction paired with easy/bright targets. Taken together, these results suggest that task-irrelevant stimuli are not subject to the attentional control mechanisms that task-relevant stimuli abide. PMID:22563424

  1. Generic cognitive adaptations to task interference in task switching.

    PubMed

    Poljac, Edita; Bekkering, Harold

    2009-11-01

    The present study investigated how the activation of previous tasks interferes with the execution of future tasks as a result of temporal manipulations. Color and shape matching tasks were organized in runs of two trials each. The tasks were specified by a cue presented before a task run, cueing only the first trials of each run. Response times (RTs) and error rates were measured for task switching and task repetition conditions. Task interference was varied as a function of response-cue interval (RCI of 300 and 900ms), that is, the interval between the task runs. Keeping the response-stimulus interval within the task runs constant at 300ms allowed the disentangling of the direct effects of RCI manipulation on performance (first trials) from the general effects on performance (both trials in the run). The data showed similar performance improvement due to RCI increase on both trials in the task run. Furthermore, increasing RCI improved both switch and repetition performance to a similar extent. Together, our findings provide further evidence for accounts stressing generic effects of proactive task interference in task switching.

  2. Suppression of the Arboviruses Dengue and Chikungunya Using a Dual-Acting Group-I Intron Coupled with Conditional Expression of the Bax C-Terminal Domain

    PubMed Central

    Carter, James R.; Taylor, Samantha; Fraser, Tresa S.; Kucharski, Cheryl A.; Dawson, James L.; Fraser, Malcolm J.

    2015-01-01

    In portions of South Asia, vectors and patients co-infected with dengue (DENV) and chikungunya (CHIKV) are on the rise, with the potential for this occurrence in other regions of the world, for example the United States. Therefore, we engineered an antiviral approach that suppresses the replication of both arboviruses in mosquito cells using a single antiviral group I intron. We devised unique configurations of internal, external, and guide sequences that permit homologous recognition and splicing with conserved target sequences in the genomes of both viruses using a single trans-splicing Group I intron, and examined their effectiveness to suppress infections of DENV and CHIKV in mosquito cells when coupled with a proapoptotic 3' exon, ΔN Bax. RT-PCR demonstrated the utility of these introns in trans-splicing the ΔN Bax sequence downstream of either the DENV or CHIKV target site in transformed Aedes albopictus C6/36 cells, independent of the order in which the virus specific targeting sequences were inserted into the construct. This trans-splicing reaction forms DENV or CHIKV ΔN Bax RNA fusions that led to apoptotic cell death as evidenced by annexin V staining, caspase, and DNA fragmentation assays. TCID50-IFA analyses demonstrate effective suppression of DENV and CHIKV infections by our anti-arbovirus group I intron approach. This represents the first report of a dual-acting Group I intron, and demonstrates that we can target DENV and CHIKV RNAs in a sequence specific manner with a single, uniquely configured CHIKV/DENV dual targeting group I intron, leading to replication suppression of both arboviruses, and thus providing a promising single antiviral for the transgenic suppression of multiple arboviruses. PMID:26580561

  3. Associative and Temporal Processes: A Dual Process Approach

    PubMed Central

    Delamater, Andrew R.; Desouza, Alex; Rivkin, Yosef; Derman, Rifka

    2013-01-01

    Approaches to the study of associative learning and interval timing have traditionally diverged on methodological and theoretical levels of analysis. However, more recent attempts have been made to explain one class of phenomena in terms of the other using various single-process approaches. In this paper we suggest that an interactive dual-process approach might more accurately reflect underlying behavioral and neural processes. We will argue that timing in Pavlovian conditioning is best understood in terms of an abstract temporal code that is not a feature of the predictive stimulus (i.e., the Conditioned Stimulus, CS), per se. Rather, we assume that the time between the CS and the unconditioned stimulus (US) is encoded in the form of an abstract representation of this temporal interval produced as an output of a central multiple-oscillator interval timing system. As such, associations can then develop between the CS and this abstract temporal code in much the same way that the CS develops associations with different features of the US. To support the dual-process approach, we first show that exposure to a Pavlovian zero contingency procedure results in a failure to acquire new associations, not a failure to express learning due to some temporally defined performance mask. We also consider evidence that supports the abstract temporal coding idea in a US preexposure task, and, finally, present some evidence to encourage the dissociation between basic associative and temporal learning processes by exploring reward devaluation effects in a peak timing task. PMID:24076309

  4. Effects of the metabotropic glutamate receptor 5 positive allosteric modulator CDPPB on rats tested with the paired associates learning task in touchscreen-equipped operant conditioning chambers.

    PubMed

    Lins, Brittney R; Howland, John G

    2016-03-15

    Effective treatments for the cognitive symptoms of schizophrenia are critically needed. Positive allosteric modulation (PAM) of metabotropic glutamate receptor subtype 5 (mGluR5) is one strategy currently under investigation to improve these symptoms. Examining cognition using touchscreen-equipped operant chambers may increase translation between preclinical and clinical research through analogous behavioral testing paradigms in rodents and humans. We used acute CDPPB (1-30mg/kg) treatment to examine the effects of mGluR5 PAM in the touchscreen paired associates learning (PAL) task using well-trained rats with and without co-administration of acute MK-801 (0.15mg/kg). CDPPB had no consistent effects on task performance when administered alone and failed to reverse the MK-801 induced impairments at any of the examined doses. Overall, the disruptive effects of MK-801 on PAL were consistent with previous research but increasing mGluR5 signaling is not beneficial in the PAL task. Future research should test whether administration of CDPPB during PAL acquisition increases performance.

  5. No transfer between conditions in balance training regimes relying on tasks with different postural demands: Specificity effects of two different serious games.

    PubMed

    Naumann, Tim; Kindermann, Stefan; Joch, Michael; Munzert, Jörn; Reiser, Mathias

    2015-03-01

    Despite the increasing use of video games involving whole body movements to enhance postural control in health prevention and rehabilitation, there is no consistent proof that training effects actually transfer to other balance tasks. The present study aimed to determine whether training effects on two different video-game-based training devices were task-specific or could be transferred to either postural control in quiet stance or to performance on the other device. 37 young healthy adults were split into three groups: two intervention groups that trained for 30min on either the Nintendo(®) Wii Fit Balance Board or the MFT Challenge Disc(®) three times per week for 4 weeks and a control group that received no training. All games require participants to control virtual avatars by shifting the center of mass in different directions. Both devices differ in their physical properties. The Balance Board provides a stable surface, whereas the Challenge Disc can be tilted in all directions. Dependent variables were the game scores on both devices and the center of pressure (COP) displacements measured via force plate. At posttest, both intervention groups showed significant increases in performance on the trained games compared to controls. However, there were no relevant transfer effects to performance on the untrained device and no changes in COP path length in quiet stance. These results suggest that training effects on both devices are highly specific and do not transfer to tasks with different postural demands.

  6. No transfer between conditions in balance training regimes relying on tasks with different postural demands: Specificity effects of two different serious games.

    PubMed

    Naumann, Tim; Kindermann, Stefan; Joch, Michael; Munzert, Jörn; Reiser, Mathias

    2015-03-01

    Despite the increasing use of video games involving whole body movements to enhance postural control in health prevention and rehabilitation, there is no consistent proof that training effects actually transfer to other balance tasks. The present study aimed to determine whether training effects on two different video-game-based training devices were task-specific or could be transferred to either postural control in quiet stance or to performance on the other device. 37 young healthy adults were split into three groups: two intervention groups that trained for 30min on either the Nintendo(®) Wii Fit Balance Board or the MFT Challenge Disc(®) three times per week for 4 weeks and a control group that received no training. All games require participants to control virtual avatars by shifting the center of mass in different directions. Both devices differ in their physical properties. The Balance Board provides a stable surface, whereas the Challenge Disc can be tilted in all directions. Dependent variables were the game scores on both devices and the center of pressure (COP) displacements measured via force plate. At posttest, both intervention groups showed significant increases in performance on the trained games compared to controls. However, there were no relevant transfer effects to performance on the untrained device and no changes in COP path length in quiet stance. These results suggest that training effects on both devices are highly specific and do not transfer to tasks with different postural demands. PMID:25791870

  7. Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

    PubMed

    Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

    2015-12-01

    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p < 0.001; SRME 7.75 vs. 2.80, p < 0.001). Similarly, secondary task performance deteriorated from baseline to dual-task among novices (RRT 0.63 vs. 1.76 s, p < 0.006 and SDR 1.00 vs. 0.27, p < 0.001), but not experts (RRT 0.63 vs. 0.73 s, p = 0.124 and SDR 1.00 vs. 0.97, p = 0.178). In phase 2, novices practiced surgical knot-tying on the bench top simulator during consecutive dual-task trials. A significant increase in SDR (F(9,63) = 6.63, p < 0.001, f = 0.97) and decrease in SRME (F(9,63) = 9.39, p < 0.001, f = 1.04) was observed during simulation training, while RRT did not change significantly (F(9,63) = 1.18, p < 0.32, f = 0.41). The results suggest subjective ratings and dual-task performance can be used to track changes in CL among novices, particularly in early phases of simulation-based skills training. The implications for measuring CL in simulation instructional design research are discussed.

  8. Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

    PubMed

    Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

    2015-12-01

    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p < 0.001; SRME 7.75 vs. 2.80, p < 0.001). Similarly, secondary task performance deteriorated from baseline to dual-task among novices (RRT 0.63 vs. 1.76 s, p < 0.006 and SDR 1.00 vs. 0.27, p < 0.001), but not experts (RRT 0.63 vs. 0.73 s, p = 0.124 and SDR 1.00 vs. 0.97, p = 0.178). In phase 2, novices practiced surgical knot-tying on the bench top simulator during consecutive dual-task trials. A significant increase in SDR (F(9,63) = 6.63, p < 0.001, f = 0.97) and decrease in SRME (F(9,63) = 9.39, p < 0.001, f = 1.04) was observed during simulation training, while RRT did not change significantly (F(9,63) = 1.18, p < 0.32, f = 0.41). The results suggest subjective ratings and dual-task performance can be used to track changes in CL among novices, particularly in early phases of simulation-based skills training. The implications for measuring CL in simulation instructional design research are discussed. PMID:25761454

  9. Task variation versus task repetition for people with profound developmental disabilities: an assessment of preferences.

    PubMed

    Lancioni, G E; O'Reilly, M F; Campodonico, F; Mantini, M

    1998-01-01

    An assessment of preferences between task variation and task repetition with four adults with profound developmental disabilities was implemented. After participants were exposed to both task variation and task repetition conditions, they were allowed to choose between them. Results showed that all participants had strong preferences; three preferred task variation and one task repetition. Aspects of the assessment and use of assessment data for planning daily work conditions were discussed.

  10. Dual Enrollment: An Analysis of Persistence, Ethnicity and Gender

    ERIC Educational Resources Information Center

    Habersham, Sherida L.

    2013-01-01

    There is a need to quantitatively relate student demographics along with dual enrollment program participation and analyze those associations on postsecondary academic persistence. This task is made more difficult in that there is limited foundation research in these areas. Further, dual enrollment programmatic guidelines differ between states.…

  11. Dual condensate and QCD phase transition

    SciTech Connect

    Zhang Bo; Bruckmann, Falk; Fodor, Zoltan; Szabo, Kalman K.; Gattringer, Christof

    2011-05-23

    The dual condensate is a new QCD phase transition order parameter, which connnects confinement and chiral symmetry breaking as different mass limits. We discuss the relation between the fermion spectrum at general boundary conditions and the dual condensate and show numerical results for the latter from unquenched SU(3) lattice configurations.

  12. Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions (Task 1) and experimental observation of dense spray and mixing of impinging jets (Task 2)

    NASA Technical Reports Server (NTRS)

    Kuo, K. K.; Hsieh, W. H.; Cheung, F. B.; Yang, A. S.; Brown, J. J.; Woodward, R. D.; Kline, M. C.; Burch, R. L.

    1992-01-01

    The objective was to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under broad range of pressure covering subcritical, critical, and supercritical conditions. The scope of the experimental work falls into the following areas: (1) design of the overall experimental setup; (2) modification of an existing windowed high pressure chamber; (3) design of the LOX feeding system; (4) provision of the safety features in the test rig design; (5) LOX cleanliness requirements; (6) cold shock testing; (7) implementation of data acquisition systems; (8) preliminary tests for system checkout; (9) modification of LOX feeding system; and (10) evaporation tests. Progress in each area is discussed.

  13. The effect of dividing attention between walking and auxiliary tasks in people with Parkinson's disease.

    PubMed

    Fok, Pamela; Farrell, Michael; McMeeken, Joan

    2012-02-01

    This controlled study examined the effects of dividing attention between walking and the performance of a secondary cognitive task in people with mild to moderate Parkinson's disease (Hoehn and Yahr stages 2-3.5). Participants in the training group (n=6) received 30 min divided attention training in taking big steps while simultaneously performing serial three subtractions. Participants in the control group (n=6) received no training. Stride length, gait velocity and accurate enumeration rate were measured at baseline, immediate after training and 30 min after training under single-task (walk only or subtract only) and dual-task (walk and subtract) conditions. Data were also collected at training in the training group. Immediate improvement in stride length and gait velocity was found when instruction was given to participants to pay equal attention to gait and subtractions (p=0.001, p=0.05) compared to baseline. Short-term improvement in the gait variables was also found after training when compared to the controls (p=0.001, p=0.001). Nevertheless, there was no significant difference in the accurate enumeration rate. Based on the findings, we conclude that divided attention can be used as a strategy to improve slow and short-stepped gait under dual-task conditions. Divided attention can also be used in gait training for short term stride length and gait velocity improvement.

  14. Task-specific Dystonias

    PubMed Central

    Torres-Russotto, Diego; Perlmutter, Joel S.

    2009-01-01

    Task-specific dystonias are primary focal dystonias characterized by excessive muscle contractions producing abnormal postures during selective motor activities that often involve highly skilled, repetitive movements. Historically these peculiar postures were considered psychogenic but have now been classified as forms of dystonia. Writer’s cramp is the most commonly identified task-specific dystonia and has features typical of this group of disorders. Symptoms may begin with lack of dexterity during performance of a specific motor task with increasingly abnormal posturing of the involved body part as motor activity continues. Initially, the dystonia may manifest only during the performance of the inciting task, but as the condition progresses it may also occur during other activities or even at rest. Neurological exam is usually unremarkable except for the dystonia-related abnormalities. Although the precise pathophysiology remains unclear, increasing evidence suggests reduced inhibition at different levels of the sensorimotor system. Symptomatic treatment options include oral medications, botulinum toxin injections, neurosurgical procedures, and adaptive strategies. Prognosis may vary depending upon body part involved and specific type of task affected. Further research may reveal new insights into the etiology, pathophysiology, natural history, and improved treatment of these conditions. PMID:18990127

  15. Effects of Practice on Task Architecture: Combined Evidence from Interference Experiments and Random-Walk Models of Decision Making

    ERIC Educational Resources Information Center

    Kamienkowski, Juan E.; Pashler, Harold; Dehaene, Stanislas; Sigman, Mariano

    2011-01-01

    Does extensive practice reduce or eliminate central interference in dual-task processing? We explored the reorganization of task architecture with practice by combining interference analysis (delays in dual-task experiment) and random-walk models of decision making (measuring the decision and non-decision contributions to RT). The main delay…

  16. Dual Diagnosis

    MedlinePlus

    ... problem. These conditions occur together frequently. In particular, alcohol and drug problems tend to occur with Depression Anxiety disorders Schizophrenia Personality disorders Sometimes the mental ...

  17. Analytical display design for flight tasks conducted under instrument meteorological conditions. [human factors engineering of pilot performance for display device design in instrument landing systems

    NASA Technical Reports Server (NTRS)

    Hess, R. A.

    1976-01-01

    Paramount to proper utilization of electronic displays is a method for determining pilot-centered display requirements. Display design should be viewed fundamentally as a guidance and control problem which has interactions with the designer's knowledge of human psychomotor activity. From this standpoint, reliable analytical models of human pilots as information processors and controllers can provide valuable insight into the display design process. A relatively straightforward, nearly algorithmic procedure for deriving model-based, pilot-centered display requirements was developed and is presented. The optimal or control theoretic pilot model serves as the backbone of the design methodology, which is specifically directed toward the synthesis of head-down, electronic, cockpit display formats. Some novel applications of the optimal pilot model are discussed. An analytical design example is offered which defines a format for the electronic display to be used in a UH-1H helicopter in a landing approach task involving longitudinal and lateral degrees of freedom.

  18. Functional mobility in a divided attention task in older adults with cognitive impairment.

    PubMed

    Borges, Sheila de Melo; Radanovic, Márcia; Forlenza, Orestes Vicente

    2015-01-01

    Motor disorders may occur in mild cognitive impairment (MCI) and at early stages of Alzheimer's disease (AD), particularly under divided attention conditions. We examined functional mobility in 104 older adults (42 with MCI, 26 with mild AD, and 36 cognitively healthy) using the Timed Up and Go test (TUG) under 4 experimental conditions: TUG single task, TUG plus a cognitive task, TUG plus a manual task, and TUG plus a cognitive and a manual task. Statistically significant differences in mean time of execution were found in all four experimental conditions when comparing MCI and controls (p < .001), and when comparing MCI and AD patients (p < .05). Receiver-operating characteristic curve analyses showed that all four testing conditions could differentiate the three groups (area under the curve > .8, p < .001 for MCI vs. controls; area under the curve > .7, p < .001 for MCI vs. AD). The authors conclude that functional motor deficits occurring in MCI can be assessed by the TUG test, in single or dual task modality. PMID:25610990

  19. Learning the way to blood: first evidence of dual olfactory conditioning in a blood-sucking insect, Rhodnius prolixus. I. Appetitive learning.

    PubMed

    Vinauger, Clément; Buratti, Laura; Lazzari, Claudio R

    2011-09-15

    It has been largely assumed that the individual experience of insects that are disease vectors might not only contribute to animal fitness, but also have an important influence on parasite transmission. Nevertheless, despite the invested efforts in testing the capacity to learn and remember information in blood-sucking insects, only little conclusive information has been obtained to date. Adapting a classical conditioning approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate L-lactic-acid, an odour perceived by these bugs but behaviourally neutral when presented alone, with food (i.e. positive reinforcement). Naive bugs--those exposed either to a conditioned stimulus (CS, L-lactic acid), unconditioned stimulus (US, heat) and reward (blood) alone or CS, US and reward in the absence of contingency--remained indifferent to the presence of an air stream loaded with L-lactic acid when tested in an olfactometer (random orientation), whereas the groups previously exposed to the contingency CS-US-reward (blood) were significantly attracted by L-lactic-acid. In a companion paper, the opposite, i.e. repellence, was induced in bugs exposed to the contingency of the same odour with a negative reinforcement. This constitutes the first evidence of olfactory conditioning in triatomine bugs, vectors of Chagas disease, and one of the few substantiations available to date of olfactory conditioning in haematophagous insects.

  20. A Comparison of the Visual Attention Patterns of People with Aphasia and Adults without Neurological Conditions for Camera-Engaged and Task-Engaged Visual Scenes

    ERIC Educational Resources Information Center

    Thiessen, Amber; Beukelman, David; Hux, Karen; Longenecker, Maria

    2016-01-01

    Purpose: The purpose of the study was to compare the visual attention patterns of adults with aphasia and adults without neurological conditions when viewing visual scenes with 2 types of engagement. Method: Eye-tracking technology was used to measure the visual attention patterns of 10 adults with aphasia and 10 adults without neurological…

  1. Learning the way to blood: first evidence of dual olfactory conditioning in a blood-sucking insect, Rhodnius prolixus. II. Aversive learning.

    PubMed

    Vinauger, Clément; Buratti, Laura; Lazzari, Claudio R

    2011-09-15

    After having demonstrated that blood-sucking bugs are able to associate a behaviourally neutral odour (L-lactic acid) with positive reinforcement (i.e. appetitive conditioning) in the first part of this study, we tested whether these insects were also able to associate the same odour with a negative reinforcement (i.e. aversive conditioning). Learned aversion to host odours has been repeatedly suggested as a determinant for the distribution of disease vectors among host populations. Nevertheless, no experimental evidence has been obtained so far. Adapting a classical conditioning approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate L-lactic acid, an odour perceived