Function Of Task Demand Research Articles

Interactions between the aging brain and motor task complexity across the lifespan: balancing brain activity resource demand and supply.

The Compensation Related Utilization of Neural Circuits Hypothesis (CRUNCH) proposes a framework for understanding task-related brain activity changes as a function of healthy aging and task complexity. Specifically, it affords the following predictions: (i) all adult age groups display more brain activation with increases in task complexity, (ii) older adults show more brain activation compared with younger adults at low task complexity levels, and (iii) disproportionately increase brain activation with increased task complexity, but (iv) show smaller (or no) increases in brain activation at the highest complexity levels. To test these hypotheses, performance on a bimanual tracking task at 4 complexity levels and associated brain activation were assessed in 3 age groups (20-40, 40-60, and 60-80years, n = 99). All age groups showed decreased tracking accuracy and increased brain activation with increased task complexity, with larger performance decrements and activation increases in the older age groups. Older adults exhibited increased brain activation at a lower complexity level, but not the predicted failure to further increase brain activity at the highest complexity level. We conclude that older adults show more brain activation than younger adults and preserve the capacity to deploy increased neural resources as a function of task demand.

Grounding Adaptive Cognitive Control in the Intrinsic, Functional Brain Organization: An HD-EEG Resting State Investigation.

In a recent study, we used the dynamic temporal prediction (DTP) task to demonstrate that the capability to implicitly adapt motor control as a function of task demand is grounded in at least three dissociable neurofunctional mechanisms: expectancy implementation, expectancy violation and response implementation, which are supported by as many distinct cortical networks. In this study, we further investigated if this ability can be predicted by the individual brain’s functional organization at rest. To this purpose, we recorded resting-state, high-density electroencephalography (HD-EEG) in healthy volunteers before performing the DTP task. This allowed us to obtain source-reconstructed cortical activity and compute whole-brain resting state functional connectivity at the source level. We then extracted phase locking values from the parceled cortex based on the Destrieux atlas to estimate individual functional connectivity at rest in the three task-related networks. Furthermore, we applied a machine-learning approach (i.e., support vector regression) and were able to predict both behavioral (response speed and accuracy adaptation) and neural (ERP modulation) task-dependent outcome. Finally, by exploiting graph theory nodal measures (i.e., degree, strength, local efficiency and clustering coefficient), we characterized the contribution of each node to the task-related neural and behavioral effects. These results show that the brain’s intrinsic functional organization can be potentially used as a predictor of the system capability to adjust motor control in a flexible and implicit way. Additionally, our findings support the theoretical framework in which cognitive control is conceived as an emergent property rooted in bottom-up associative learning processes.

Age-related differences in calf muscle recruitment strategies in the time-frequency domain during walking as a function of task demand.

Activation of the plantar flexors is critical in governing ankle push-off power during walking, which decreases due to age. However, electromyographic (EMG) signal amplitude alone is unable to fully characterize motor unit recruitment during functional activity. Although not yet studied in walking, EMG frequency content may also vary due to age-related differences in muscle morphology and neural signaling. Our purpose was to quantify plantar flexor activation differences in the time-frequency domain between young and older adults during walking across a range of speeds and with and without horizontal aiding and impeding forces. Ten healthy young (24.0 ± 3.4 yr) and older adults (73.7 ± 3.9 yr) walked at three speeds and walked with horizontal aiding and impeding force while muscle activations of soleus (SOL) and gastrocnemius (GAS) were recorded. The EMG signals were decomposed in the time-frequency domain with wavelet transformation. Principal component analyses extracted principal components (PCs) and PC scores. Compared with young adults, we observed that GAS activation in older adults: 1) was lower across all frequency ranges during midstance and in slow to middle frequency ranges during push-off, independent of walking speed and 2) shifted to slower frequencies with earlier timing as walking speed increased. Our results implicate GAS time-frequency content, and its morphological and neural origins, as a potential determinant of hallmark ankle push-off deficits due to aging, particularly at faster walking speeds. Rehabilitation specialists may attempt to restore GAS intensity across all frequency ranges during mid-to-late stance while avoiding disproportionate increases in slower frequencies during early stance.NEW & NOTEWORTHY We use time-frequency analyses of calf muscle activation to quantify age-related differences in motor recruitment in walking. Gastrocnemius activation in older versus young adults was lower across all frequencies during midstance and in slow-to-middle frequencies during push-off, independent of speed, and shifted to slower frequencies with earlier timing as speed increased. Our results implicate gastrocnemius time-frequency content as a potential determinant of hallmark ankle push-off deficits due to aging, particularly at faster speeds.

Energy investment and motivation: The additive impact of task demand and reward value on exerted force in hand grip tasks

According to motivational intensity theory, individuals are motivated to conserve energy when pursuing goals. They should invest only the energy required for success and disengage if success is not important enough to justify the required energy. We tested this hypothesis in five experiments assessing exerted muscle force in isometric hand grip tasks as indicator of energy investment. Our results provided mixed evidence for motivational intensity theory. Corroborating its predictions, energy investment was a function of task demand. However, we did not find evidence for the predicted disengagement, and we observed that participants exerted in most conditions more force than required. Furthermore, the data could be better explained by a model that predicted an additive effect of task demand and success importance than by models drawing on motivational intensity theory’s predictions. These results illustrate the strong link between energy investment and task demand but challenge motivational intensity theory’s primacy of energy conservation.

Investigating the Influences of Task Demand and Reward on Cardiac Pre-Ejection Period Reactivity During a Speech-in-Noise Task.

Objectives:Effort investment during listening varies as a function of task demand and motivation. Several studies have manipulated both these factors to elicit and measure changes in effort associated with listening. The cardiac pre-ejection period (PEP) is a relatively novel measure in the field of cognitive hearing science. This measure, which reflects sympathetic nervous system activity on the heart, has previously been implemented during a tone discrimination task but not during a speech-in-noise task. Therefore, the primary goal of this study was to explore the influences of signal to noise ratio (SNR) and monetary reward level on PEP reactivity during a speech-in-noise task.Design:Thirty-two participants with normal hearing (mean age = 22.22 years, SD = 3.03) were recruited at VU University Medical Center. Participants completed a Dutch speech-in-noise test with a single-interfering-talker masking noise. Six fixed SNRs, selected to span the entire psychometric performance curve, were presented in a block-wise fashion. Participants could earn a low (€0.20) or high (€5.00) reward by obtaining a score of ≥70% of words correct in each block. The authors analyzed PEP reactivity: the change in PEP measured during the task, relative to the baseline during rest. Two separate methods of PEP analysis were used, one including data from the whole task block and the other including data obtained during presentation of the target sentences only. After each block, participants rated their effort investment, performance, tendency to give up, and the perceived difficulty of the task. They also completed the need for recovery questionnaire and the reading span test, which are indices of additional factors (fatigue and working memory capacity, respectively) that are known to influence listening effort.Results:Average sentence perception scores ranged from 2.73 to 91.62%, revealing a significant effect of SNR. In addition, an improvement in performance was elicited by the high, compared to the low reward level. A linear relationship between SNR and PEP reactivity was demonstrated: at the lower SNRs PEP reactivity was the most negative, indicating greater effort investment compared to the higher SNRs. The target stimuli method of PEP analysis was more sensitive to this effect than the block-wise method. Contrary to expectations, no significant impact of reward on PEP reactivity was found in the present dataset. Also, there was no physiological evidence that participants were disengaged, even when performance was poor. A significant correlation between need for recovery scores and average PEP reactivity was demonstrated, indicating that a lower need for recovery was associated with less effort investment.Conclusions:This study successfully implemented the measurement of PEP during a standard speech-in-noise test and included two distinct methods of PEP analysis. The results revealed for the first time that PEP reactivity varies linearly with task demand during a speech-in-noise task, although the effect size was small. No effect of reward on PEP was demonstrated. Finally, participants with a higher need for recovery score invested more effort, as shown by average PEP reactivity, than those with a lower need for recovery score.

Impacts of trait anxiety on visual working memory, as a function of task demand and situational stress

ABSTRACT Higher trait anxiety can impair cognitive functioning via attention, but relatively little is known about the impacts on visual working memory. These were investigated using previously validated visual feature binding tasks. In Study 1, participants' memory for visual features (shapes) and feature bindings (coloured shapes) was assessed. Stimulus presentation was simultaneous or sequential, varying attentional demand, and participants were grouped according to trait cognitive anxiety (low, moderate, high). No reliable effect of trait anxiety, either cognitive or somatic, was found on memory accuracy, but moderate trait cognitive anxiety was associated with faster correct response times (i.e. increased efficiency) when stimuli were sequentially presented. In Study 2, the role of situational stress was explored during a simultaneously presented task. Higher trait cognitive and somatic anxiety were both associated with poorer efficiency during both shape and binding memory tasks. Trait somatic anxiety also predicted poorer binding effectiveness (i.e. accuracy), in those reporting higher state cognitive anxiety. Situational stress predicted binding effectiveness, but never interacted with trait anxiety, and was therefore not necessary to observe these trait anxiety-visual working memory relationships. Trait cognitive and somatic anxiety, and situational stress, therefore each influence visual working memory performance.

The role of reward and task demand in value-based strategic allocation of auditory comprehension effort

ObjectivesListeners who fail to optimize their allocation of effort during auditory comprehension tasks can experience from compromised performance, fatigue and stress, which might result in reduced engagement in social communication activities. Strategically allocating effort based on costs and perceived benefits are commonly observed in the research of effortful physical and visual behaviors. Whether people manage their effort in a similar manner in audition remains unclear. As the listening performance of people with normal hearing often serves as the goal of auditory rehabilitation for people with hearing loss, this study evaluated how strategy-induced effort allocation, challenged by reward and task demand, interactively impacted auditory comprehension in normal hearing adults. DesignA value-based strategic effort allocation paradigm was evaluated in 40 normal-hearing young adults. The paradigm included five levels of reward (motivation) and five levels of task demand (speech rate) that were independently manipulated. Effects of reward and task demand on performance accuracy and pupil dilation (a measure of auditory comprehension effort) were examined. ResultsThere was a significant interaction effect of reward and task demand on both pupil dilation and comprehension accuracy. At the response stage of speech comprehension processing, pupil dilation significantly decreased as the task demand increased at high reward levels. In contrast, pupil dilation did not vary significantly as a function of task demand at low reward levels. Reward significantly improved performance accuracy at fast and extremely fast rate conditions, but not at the slower rates. ConclusionsConsistent with previous studies on effort regulation, reward and task demand appear to be associated with auditory comprehension effort allocation in an interactive manner when strategic effort control was required to achieve a reward goal. The young normal-hearing listeners in this study prioritized their effort to relatively easy task items over difficult ones at high levels of reward, suggesting a cost-effective value-based strategic effort allocation. Reward significantly improved task performance in terms of accuracy at difficult listening conditions. These findings support the incorporation of affective factors (e.g., reward) and the utility of the value-based strategic effort allocation paradigm in the experimental setting to understand how clinically relevant factors (such as hearing loss and age) might change strategic auditory comprehension behavior.

Comparing drivers’ visual attention at Junctions in Real and Simulated Environments

Driving simulation is widely used to answer important applied research questions, however, it is vital for specific driving tasks to undergo appropriate behavioural validation testing. Many previous validation studies have used simple driving tasks and measured relatively low-level vehicle control. The purpose of the current study was to investigate whether drivers’ visual attention at intersections with different levels of demand, are similar in the simulator and on the road. Unlike simpler driving tasks, crossing intersections requires complex interactions with other vehicles governed by sequences of head and eye movements that may not be accurately captured in a simulated environment.In the current study we directly compare performance at simulated junctions with the same participants' behaviour in a real car. We compared drivers’ visual attention in a high-fidelity driving simulator (instrumented car, 360-degree screen) and on-road in both low and medium demand driving situations. The low and medium demand driving situations involved the same motor movements, containing straight on, right turn and left turn manoeuvres. The low demand situations were controlled by the road environment and traffic lights, whereas medium demand situations required the driver to scan the environment and decide when it was safe to pull out into the junction. Natural junctions in Nottingham were used for the on-road phase and the same junctions were recreated in the simulator with traffic levels matched to those that were encountered on the real roads.The frequency and size of drivers' head movements were not significantly different between manoeuvres performed in the simulator and those conducted when driving on real roads. This suggests that drivers' broad search strategies in the simulator are representative of real-world driving. These strategies did change as a function of task demand - compared to low demand situations, behaviour at the medium demand junctions was characterised by longer junction crossing times, more head movements, shorter fixation durations and larger saccadic amplitudes. Although patterns of head movements were equivalent on road and in the simulator, there were differences in more fine-grained measures of eye-movements. Mean fixation durations were longer in the simulator compared to on-road, particularly in low-demand situations. We interpret this as evidence for lower levels of visual engagement with the simulated environment compared to the real world, at least when the task demands are low. These results have important implications for driving research. They suggest that high fidelity driving simulators can be useful tools for investigating drivers’ visual attention at junctions, particularly when the driving task is of at least moderate demand.

Volitional media multitasking: awareness of performance costs and modulation of media multitasking as a function of task demand.

In two experiments, we sought to determine whether (a) people are aware of the frequently observed performance costs associated with engaging in media multitasking (Experiment 1), and (b) if so, whether they modulate the extent to which they engage in multitasking as a function of task demand (Experiment 2). In Experiment 1, participants completed a high-demand task (2-back) both independently and while a video was simultaneously presented. To determine whether people were sensitive to the impact that the concurrent video had on primary-task performance, subjective estimates of performance were collected following both trial types (No-Video vs. Video trials), as were explicit beliefs about the influence of the video on performance. In Experiment 2, we modified our paradigm by allowing participants to turn the video on and off at their discretion, and had them complete either a high-demand task (2-back) or a low-demand task (0-back). Findings from Experiment 1 indicated that people are sensitive to the magnitude of the decrement that media multitasking has on primary-task performance. In addition, findings from Experiment 2 indicated that people modulate the extent to which they engage in media multitasking in accordance with the demands of their primary task. In particular, participants completing the high-demand task were more likely to turn off the optional video stream compared to those completing the low-demand task. The results suggest that people media multitask in a strategic manner by balancing considerations of task performance with other potential concerns.

Eating ghosts: The underlying mechanisms of mood repair via interactive and noninteractive media.

Mood repair is a well-established function of media usage implying distraction from negative mood and the modification of unpleasant arousal states. Recent studies have found interactive media, in particular computer games, to be more effective in repairing mood than noninteractive media. It has been suggested that this is due to the higher task demand of interactive media distracting the players from negative feelings. Yet interactive media have also been found to increase arousal, which can also be seen as a cause for successful mood repair. It remains an open question which mechanism or to which degree both mechanisms-distraction and arousal regulation-account for mood repair via interactive media. The current study was designed to examine this so far unanswered question. We analyzed how effectively negative moods were regulated after a computer game, after a gameplay video, and without media consumption (control group). Mood repair, physiological arousal (positive change in electrodermal activity), and subjective arousal were assessed. Results confirmed that computer games led to a higher degree of mood repair and that this repair was a function of task demand as well as arousal characteristics. Results are discussed in terms of arousal regulation and intervention potential in interactive media.

Eye Glance and Head Turn Correspondence during Secondary Task Performance in Simulator Driving

This paper and its findings serve as a fundamental characterization of the interaction between the head and eye as a function of task demand and duration while driving. These findings have potential use in future vehicle active safety, and the design of driver assistance and/or HMI systems and features. Our findings show that head position and eye-point-of regard for certain task locations have dependence and may be suited to characterize task engagement while driving.

Aberrant neural mediation of verbal fluency in autism spectrum disorders

ObjectiveContrasts of verbal fluency and automatic speech provide an opportunity to evaluate the neural underpinnings of generativity and flexibility in autism spectrum disorders (ASD). MethodWe used functional magnetic resonance imaging (fMRI) to contrast brain activity in high functioning ASD (n=17, mean verbal IQ=117) and neurotypical (NT; n=20, mean verbal IQ=112) adolescent and young adult males (12–23years). Participants responded to three word generation conditions: automatic speech (reciting months), category fluency, and letter fluency. ResultsOur paradigm closely mirrored behavioral fluency tasks by requiring overt, free recall word generation while controlling for differences in verbal output between the groups and systematically increasing the task demand. The ASD group showed reduced neural response compared to the NT participants during fluency tasks in multiple regions of left anterior and posterior cortices, and sub-cortical structures. Six of these regions fell in cortico-striatal circuits previously linked to repetitive behaviors (Langen, Durston, Kas, van Engeland, & Staal, 2011), and activity in two of them (putamen and thalamus) was negatively correlated with autism repetitive behavior symptoms in the ASD group. In addition, response in left inferior frontal gyrus was differentially modulated in the ASD, relative to the NT, group as a function of task demand. ConclusionsThese data indicate a specific, atypical brain response in ASD to demanding generativity tasks that may have relevance to repetitive behavior symptoms in ASD as well as to difficulties generating original verbal responses.

Neural Recruitment after Mild Traumatic Brain Injury Is Task Dependent: A Meta-analysis

Individuals with mild traumatic brain injury (TBI) often have deficits in processing speed and working memory (WM) and there is a growing literature using functional imaging studies to document these deficits. However, divergent results from these studies revealed both hypoactivation and hyperactivation of neural resources after injury. We hypothesized that at least part of this variance can be explained by distinct demands between WM tasks. Notably, in this literature some WM tasks use discrete periods of encoding, maintenance, and retrieval, whereas others place continuous demands on WM. The purpose of this meta-analysis is to examine the differences in neural recruitment after mTBI to determine if divergent findings can be explained as a function of task demand and cognitive load. A comprehensive literature review revealed 14 studies using functional magnetic resonance imaging to examine brain activity of individuals with mTBI during working memory tasks. Three of the fourteen studies included reported hypoactivity, five reported hyperactivity, and the remaining six reported both hypoactivity and hyperactivity. Studies were grouped according to task type and submitted to GingerALE maximum likelihood meta-analyses to determine the most consistent brain activation patterns. The primary findings from this meta-analysis suggest that the discrepancy in activation patterns is at least partially attributable to the classification of WM task, with hyperactivation being observed in continuous tasks and hypoactivation being observed during discrete tasks. We anticipate that differential task load expressed in continuous and discrete WM tasks contributes to these differences. Implications for the interpretation of fMRI signals in clinical samples are discussed.

Task difficulty modulates young–old differences in network expression

The extent of task-related fMRI activation can vary as a function of task difficulty. Also the efficiency or capacity of the brain networks underlying task performance can change with aging. We asked whether the expression of a network underlying task performance would differ as a function of task demand in old and young individuals. 26 younger and 23 older healthy adults performed a delayed item recognition task that used the response signal method to parametrically manipulate the extrinsic difficulty of the task by imposing five different deadlines for recognition response. Both age groups showed a speed–accuracy trade-off, but the younger group achieved greater discriminability at the longer deadlines. We identified a spatial pattern of fMRI activation during the probe phase whose expression increased as the response deadline shortened and the task became more difficult. This pattern was expressed to a greater degree by the old group at the long deadlines, when the task was easiest. By contrast, this pattern was expressed to a greater degree by the younger group at the short deadlines, when the task was hardest. This suggests reduced efficiency and capacity of this network in older subjects. These findings suggest that neuroimaging studies comparing task-related activation across groups with different cognitive abilities must be interpreted in light of the relative difficulty of the task for each group.

Friend/Foe Identification and Shooting Performance: Effects of Prior Task Loading and Time Pressure

The current dismounted soldier and the soldier of the future will be “loaded” with more information processing tasks while they perform shooting tasks. It is conceivable that some increased level of cognitive tasking may be performed simultaneously with required shooting tasks. The current was conducted in a high fidelity mixed reality simulation environment SAST-II. The study was designed to examine the ability of the soldier to perform friend-foe target discrimination and shooting accuracy, with varying target exposure times, friendly target signatures, and varying cognitive load demands. Analysis of variance revealed significant differences for the memory recall task during shooting and non-shooting conditions. Furthermore, results showed that workload increased as a function of task demand, with associated decreases in shooting performance.

Adductor spasmodic dysphonia and muscular tension dysphonia: Acoustic analysis of sustained phonation and reading

Acoustic phonatory events were identified in 10 women diagnosed with adductor spasmodic dysphonia (ADSD) and compared to 5 women and 5 men diagnosed with muscle tension dysphonia (MTD). The three acoustic parameters examined during sustained vowel production and reading included phonatory breaks, aperiodicity, and frequency shifts. Intra- and intermeasurer correlations showed high reliability for the measures. Findings indicated that those with ADSD produced a greater number of aberrant acoustic events than those with MTD. The results suggested that: (1) only those with ADSD show evidence of phonatory breaks during vocalization, albeit a sustained vowel or voicing during reading; (2) those with ADSD demonstrate greater variation in the type of aberrant acoustic events produced as a function of speech task. The latter point suggests that control of the larynx varies as a function of task demand, a finding not evident in the functionally based disorder of MTD. MTD is a disorder that often presents itself in a similar clinical manner to ADSD because of its perceptual commonalties and resembling laryngoscopic characteristics. The acoustic analysis presented in this study could be used as a method to assist in distinguishing between the two disorder types.

Effects of situational demands on the direction of electrodermal activation during smoking

Task demands (normal smoking; sham smoking; smoking or non-smoking during complex cognitive performance; and, smoking or non-smoking during monotonous vigilance performance) were manipulated in three experiments. Smoking increased electrodermal activity (EDA) arousal from pre-smoking baseline. Sham smoking (as a control for motoric aspects) also increased EDA arousal but to a lesser degree. In contrast the demands of complex cognitive performance were associated with lower EDA arousal during smoking than during non-smoking. Finally, during vigilance performance smoking maintained EDA arousal which during non-smoking decreased. Smoking did not improve performance during complex cognitive processing or vigilance above deprivation performance levels. It was concluded that smoking did have bidirectional effects as a function of task demand. However, there was no evidence that these physiological changes were functional and the smoking behavior data gave no indication as to the cause of these changes.

Variations in attention as a function of classroom task demands in learning handicapped and CA-matched nonhandicapped children.

This study was conducted to examine behaviors reflecting attention among learning handicapped and normal youngsters while they worked on tasks that varied in cognitive demand. Children were individually observed while they worked in their classroom. Results indicated that normal youngsters spent about 80% of observed time on-task regardless of task demands. Learning handicapped youngsters varied in their on-task behavior as a function of task demand: They spent least time on-task when cognitive demands were greatest and most time on-task when few cognitive demands were made. Implications of these findings were discussed.