Executive Demands Research Articles

Baseline Cognitive Performance Moderates the Effects of Physical Activity on Executive Functions in Children.

Findings regarding the effects of regular physical activity on cognition in children have been inconsistent due to a number of demographic factors and experimental considerations. The present study was designed to examine baseline cognitive performance and executive function demands, as possible factors underlying the lack of consensus in the literature, by investigating the moderating role of those factors on the effects of physical activity on cognition. We reanalyzed data from three randomized controlled trials, in which the effects of regular physical activity intervention on cognition were examined using executive function tasks that included at least two task conditions requiring variable executive function demands, with a cumulative total of 292 participants (9–13 years). The results indicate that cognitive improvements resulting from physical activity intervention were greater in children with lower baseline cognitive performance. The main analysis revealed that beneficial effects of physical activity intervention on cognitive performance were generally observed across executive function conditions. However, secondary analyses indicated that these general effects were moderated by baseline performance, with disproportionately greater effects for task conditions with higher executive function demands. These findings suggest that baseline cognitive performance is an individual difference variable that moderates the beneficial effects of physical activity on executive functions.

Determinants of Gender Differences in Change in Pay among Job-Switching Executives

The authors investigate what determines differences in change in pay between men and women executives who move to new employers. Using proprietary data of 2,034 executive placements from a global search firm, the authors observe narrower pay differences between men and women after job moves. The unconditional gap shrinks from 21.5% in the prior employer to 15% in the new employer. After controlling for typical explanatory factors, the residual gap falls by almost 30%, from 8.5% at the prior employer to 6.1% in the new placement. This change reflects a relative increase in performance-based compensation for women and a lower level of unexplained pay inequality generally in external placements. Controlling for individual fixed effects, observed women have higher pay raises than do men. Finally, the authors find suggestive evidence that pay differences may also be moderated by differences in the supply and demand for women executives.

Memory in autism spectrum disorder: A meta-analysis of experimental studies.

To address inconsistencies in the literature on memory in autism spectrum disorder (ASD), we report the first ever meta-analysis of short-term memory (STM) and episodic long-term memory (LTM) in ASD, evaluating the effects of type of material, type of retrieval and the role of interitem relations. Analysis of 64 studies comparing individuals with ASD and typical development (TD) showed greater difficulties in ASD compared with TD individuals in STM (Hedges' g = -0.53, 95% CI [-0.90, -0.16], p = .005, I² = 96%) compared with LTM (g = -0.30, 95% CI [-0.42, -0.17], p < .00001, I² = 24%), a small difficulty in verbal LTM (g = -0.21, p = .01), contrasting with a medium difficulty for visual LTM (g = -0.41, p = .0002) in ASD compared with TD individuals. We also found a general diminution in free recall compared with cued recall and recognition (LTM, free recall: g = -0.38, p < .00001, cued recall: g = -0.08, p = .58, recognition: g = -0.15, p = .16; STM, free recall: g = -0.59, p = .004, recognition: g = -0.33, p = .07). We discuss these results in terms of their relation to semantic memory. The limited diminution in verbal LTM and preserved overall recognition and cued recall (supported retrieval) may result from a greater overlap of these tasks with semantic long-term representations which are overall preserved in ASD. By contrast, difficulties in STM or free recall may result from less overlap with the semantic system or may involve additional cognitive operations and executive demands. These findings highlight the need to support STM functioning in ASD and acknowledge the potential benefit of using verbal materials at encoding and broader forms of memory support at retrieval to enhance performance. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Impact of an Individualized Cognitive Training Intervention in Preschoolers from Poor Homes.

Over the last few decades, different interventions were shown to be effective in changing cognitive performance in preschoolers from poor homes undertaking tasks with executive demands. However, this evidence also showed that not all children included in the intervention groups equally increased their performance levels, which could be related to individual and contextual variability. The present study aimed to explore the impact of a computerized cognitive training intervention with lab-based tasks in preschoolers from Unsatisfied Basic Needs (UBN) homes under the consideration of their baseline performance. In the context of a randomized controlled trial design, different interventions were administered to children according to their baseline performance in a variety of cognitive tasks (i.e., executive attention, inhibitory control, working memory, and planning demands). The results showed different patterns of impact on performance depending on the experimental group, supporting the importance of considering individual and contextual differences in the design of interventions aimed at optimizing executive functions in poverty-impacted sample populations in early stages of development.

The Witness-Aimed First Account (WAFA): A new technique for interviewing autistic witnesses and victims.

Autistic people experience social communication difficulties alongside specific memory difficulties than impact their ability to recall episodic events. Police interviewing techniques do not take account of these differences, and so are often ineffective. Here we introduce a novel Witness-Aimed First Account interview technique, designed to better support autistic witnesses by diminishing socio-cognitive and executive demands through encouraging participants to generate and direct their own discrete, parameter-bound event topics, before freely recalling information within each parameter-bound topic. Since witnessed events are rarely cohesive stories with a logical chain of events, we also explored witnesses’ recall when the narrative structure of the to-be-remembered event was lost. Thirty-three autistic and 30 typically developing participants were interviewed about their memory for two videos depicting criminal events. Clip segments of one video were ‘scrambled’, disrupting the event’s narrative structure; the other video was watched intact. Although both autistic and typically developing witnesses recalled fewer details with less accuracy from the scrambled video, Witness-Aimed First Account interviews resulted in more detailed and accurate recall from autistic and typically developing witnesses, for both scrambled and unscrambled videos. The Witness-Aimed First Account technique may be a useful tool to improve autistic and typically developing witnesses’ accounts within a legally appropriate, non-leading framework.Lay abstractAutistic people may be more likely to be interviewed by police as a victim/witness, yet they experience social communication difficulties alongside specific memory difficulties that can impact their ability to recall information from memory. Police interviewing techniques do not take account of these differences, and so are often ineffective. We developed a new technique for interviewing autistic witnesses, referred to a Witness-Aimed First Account, which was designed to better support differences in the way that autistic witnesses process information in memory. The Witness-Aimed First Account technique encourages witnesses to first segment the witnessed event into discrete, parameter-bound event topics, which are then displayed on post-it notes while the witness goes onto freely recall as much information as they can from within each parameter-bound topic in turn. Since witnessed events are rarely cohesive stories with a logical chain of events, we also explored autistic and non-autistic witnesses’ recall when the events were witnessed in a random (nonsensical) order. Thirty-three autistic and 30 typically developing participants were interviewed about their memory for two videos depicting criminal events. Clip segments of one video were ‘scrambled’, disrupting the event’s narrative structure; the other video was watched intact. Although both autistic and non-autistic witnesses recalled fewer details with less accuracy from the scrambled video, Witness-Aimed First Account interviews resulted in more detailed and accurate recall from both autistic and non-autistic witnesses, for both scrambled and unscrambled videos. The Witness-Aimed First Account technique may be a useful tool to improve witnesses’ accounts within a legally appropriate, non-leading framework.

Pro- and antisaccade task-switching: response suppression-and not vector inversion-contributes to a task-set inertia.

Alternating between different tasks represents an executive function essential to activities of daily living. In the oculomotor literature, reaction times (RT) for a 'standard' and stimulus-driven (SD) prosaccade (i.e., saccade to target at target onset) are increased when preceded by a 'non-standard' antisaccade (i.e., saccade mirror-symmetrical to target at target onset), whereas the converse switch does not elicit an RT cost. The prosaccade switch-cost has been attributed to lingering neural activity-or task-set inertia-related to the antisaccade executive demands of response suppression and vector inversion. It is, however, unclear whether response suppression and/or vector inversion contribute to the prosaccade switch-cost. Experiment 1 of the present work had participants alternate (i.e., AABB paradigm) between minimally delayed (MD) pro- and antisaccades. MD saccades require a response after target extinction and necessitate response suppression for both pro- and antisaccades-a paradigm providing a framework to determine whether vector inversion contributes to a task-set inertia. In Experiment 2, participants alternated between SD pro- and MD antisaccades-a paradigm designed to determine if a switch-cost is selectively imparted when a SD and standard response is preceded by a non-standard response. Experiment 1 showed that RTs for MD pro- and antisaccades were refractory to the preceding trial-type; that is, vector inversion did not engender a switch-cost. Experiment 2 indicated that RTs for SD prosaccades were increased when preceded by an MD antisaccade. Accordingly, response suppression engenders a task-set inertia but only for a subsequent stimulus-driven and standard response (i.e., SD prosaccade). Such a result is in line with the view that response suppression is a hallmark feature of executive function.

HEARS: A heterogeneous energy-aware real-time scheduler

Developing energy-efficient schedulers for real-time heterogeneous platforms executing periodic tasks is an onerous as well as a computationally challenging problem. As a result, today we are confronting a scarcity of real-time energy-aware scheduling techniques which are applicable to heterogeneous platforms. Hence, this research proposes a heuristic strategy called, HEARS, for DVFS enabled energy-aware scheduling of a set of periodic tasks executing on a heterogeneous multicore system having an arbitrary number of core types. The presented scheme first applies deadline-partitioning to acquire a set of distinct time-intervals called frames. At any frame boundary, the following two-phase hierarchical operation is applied to obtain schedule for the next frame: First, it computes execution requirements for each task on every processing core of the platform. For any task, its execution requirement on a core within a frame depends upon the following criteria: (i) Length of the ensuing frame, (ii) Total execution requirements of the instance of the task on different cores (as a single task may have different execution requirement on different cores) and, (iii) Deadline of the instance of the task. Next, it simultaneously allocates each task on one or more cores and selects operating frequencies for the concerned cores such that the total execution demand of all the allocated tasks are satisfied as well as there is minimum change in energy consumption for the system. Experimental results show that our proposed strategy is not only able to achieve appreciable energy savings with respect to state-of-the-art MaxMin (2% to 37% on average) but also enables significant improvement in resource utilization (as high as 57%).

Antipointing Reaches Do Not Adhere to Width-Based Manipulations of Fitts’ (1954) Equation

Reaches with overlapping stimulus-response spatial relations (propointing) adhere to speed-accuracy relations as defined by Paul Fitts' index of difficulty equation (IDFitts: in bits of information). This movement principle is attributed to response mediation via the "fast" visuomotor networks of the dorsal visual pathway. It is, however, unclear whether the executive demands of dissociating stimulus-response spatial relations by reachingmirror-symmetrical to a target (antipointing) elicits similar adherence to Fitts' equation. Here, pro- and antipointing responses were directed to a constant target amplitude with varying target widths to provide IDFitts values of 3.0, 3.5, 4.3, and 6.3 bits. Propointing movement times linearly increased with IDFitts-a result attributed to visually based trajectory corrections. In contrast, antipointing movement times, deceleration times, and endpoint precision did not adhere to Fitts' equation. These results indicate that antipointing renders a "slow" and offline mode of control mediated by the visuoperceptual networks of the ventral visual pathway.

The ANT Executive Control Index: No Evidence for Temporal Decrement.

This study tested whether indices of executive control, alertness, and orienting measured with Attention Network Test (ANT) are vulnerable to temporal decrement in performance. Developing the resource theory of sustained attention requires identifying neurocognitive processes vulnerable to decrement. Executive control processes may be prone to impairment in fatigue states. Such processes are also highlighted in alternative theories. Determining the role of executive control in vigilance can both advance theory and contribute to practical countermeasures for decrement in human factors contexts. In Study 1, 80 participants performed the standard ANT for an extended duration of about 55 to 60 min. Study 2 (160 participants) introduced manipulations of trial blocking and stimulus degradation intended to increase resource depletion. Reaction time and accuracy measures were analyzed. Subjective stress and workload were assessed in both studies. In both studies, the ANT induced levels of subjective workload and task disengagement consistent with previous sustained attention studies. No systematic decrement in any performance measure was observed. Executive control assessed by the ANT is not highly vulnerable to temporal decrement, even when task demands are elevated. Future work should differentiate executive control processes; proactive control may be more implicated in sustained attention decrement than in reactive control. Designing systems and interfaces to reduce executive control demands may be generally beneficial but will not directly mitigate temporal performance decrement. Enhancing design guidelines and neuroergonomic methods for monitoring operator attention requires further work to identify key neurocognitive processes for decrement.

Conceptual flexibility in school children: Switching between taxonomic and thematic relations

Conceptual flexibility is the skill of categorizing a single object in different ways on separate occasions (e.g. first taxonomically: DOG-COW, and then thematically: DOG-DOGHOUSE). This skill contributes to the efficient organization of information and to adaptive behavior. Although several studies have tested whether children can categorize objects perceptually, thematically and taxonomically, few have explored if they can apply different categorization criteria to the same set of objects. This study, therefore, presents two experimental tasks conducted to assess conceptual flexibility in 6-to 11-year-old-primary school children from Mar del Plata, Argentina. Findings indicate that conceptual flexibility increases at age 10–11 in the task with the greater executive demand (multiple free sorting -MFS-) and both in 8–9 and 10–11 age groups in the task with the lesser executive demand (triple forced choice -TFC-), thanks to the appearance of taxonomic responses. Thematic relations proved to be especially prominent and influential; and during much of childhood, superordinate taxonomic knowledge remains inaccessible in comparison to thematic knowledge.

Explaining age-related decline in theory of mind: Evidence for intact competence but compromised executive function

Previous studies suggest theory of mind (ToM) ability declines with age. However, prior tasks not only required ToM competence but also imposed high executive function (EF) demands, so decline in ToM ability could be caused by deterioration in ToM competence, EF, or both. It was predicted that if the elderly have intact ToM competence but compromised EF, then they should perform similarly to younger adults when using ToM tasks that lower executive demands, such as spontaneous-response tasks. Results showed that on tasks with reduced demands, older adults tracked belief to the same extent as younger adults, despite their declining EF. The findings support a model in which age-related decline in ToM ability is primarily caused by compromised EF, not ToM competence, suggesting that underlying ToM mechanisms are still intact in the elderly. We discuss implications of this work for competence-performance issues in ToM processing and the underlying sources of age-related deterioration of ToM.

Data-driven identification of subtypes of executive function across typical development, attention deficit hyperactivity disorder, and autism spectrum disorders.

Impairment of executive function (EF), the goal-directed regulation of thoughts, actions, and emotions, drives negative outcomes and is common across neurodevelopmental disorders including attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). A primary challenge to its amelioration is heterogeneity in symptom expression within and across disorders. Parsing this heterogeneity is necessary to attain diagnostic precision, a goal of the NIMH Research Domain Criteria Initiative. We aimed to identify transdiagnostic subtypes of EF that span the normal to impaired spectrum and establish their predictive and neurobiological validity. Community detection was applied to clinical parent-report measures in 8-14-year-old children with and without ADHD and ASD from two independent cohorts (discovery N=320; replication N=692) to identify subgroups with distinct behavioral profiles. Support vector machine (SVM) classification was used to predict subgroup membership of unseen cases. Preliminary neurobiological validation was obtained with existing functional magnetic resonance imaging (fMRI) data on a subsample (N=84) by testing hypotheses about sensitivity of EF subgroups versus DSM categories. We observed three transdiagnostic EF subtypes characterized by behavioral profiles that were defined by relative weakness in: (a) flexibility and emotion regulation; (b) inhibition; and (c) working memory, organization, and planning. The same tripartite structure was also present in the typically developing children. SVM trained on the discovery sample and tested on the replication sample classified subgroup membership with 77.0% accuracy. Split-half SVM classification on the combined sample (N=1,012) yielded 88.9% accuracy (this SVM is available for public use). As hypothesized, frontal-parietal engagement was better distinguished by EF subtype than DSM diagnosis and the subgroup characterized with inflexibility failed to modulate right IPL activation in response to increased executive demands. The observed transdiagnostic subtypes refine current diagnostic nosology and augment clinical decision-making for personalizing treatment of executive dysfunction in children.

Dyslexia-related impairments in sequence learning predict linguistic abilities

Dyslexia is often characterized by disordered word recognition and spelling, though dysfunction on various non-linguistic tasks suggests a more pervasive deficit may underlie reading and spelling abilities. The serial-order learning impairment in dyslexia (SOLID) hypothesis proposes that sequence learning impairments fundamentally disrupt cognitive abilities, including linguistic processes, among individuals with dyslexia; yet only some studies report sequence learning deficits in people with dyslexia relative to controls. Evidence may be mixed because traditional sequence learning tasks often require strong motor demands, working memory processes and/or executive functions, wherein people with dyslexia can show impairments. Thus, observed sequence learning deficits in dyslexia may only appear to the extent that comorbid motor-based processes, memory capacity, or executive processes are involved. The present study measured sequence learning in college-aged students with and without dyslexia using a single task that evaluates sequencing and non-sequencing components but without strong motor, executive, or memory demands. During sequencing, each additional link in a sequence of stimuli leading to a reward is trained step-by-step, until a complete sequence is acquired. People with dyslexia made significantly more sequencing errors than controls, despite equivalent performance on non-sequencing components. Mediation analyses further revealed that sequence learning accounted for a large portion of the variance between dyslexia status and linguistic abilities, particularly pseudo-word reading. These findings extend the SOLID hypothesis by showing difficulties in the ability to acquire sequences that may play an underlying role in literacy acquisition.

HEALERS: a heterogeneous energy‐aware low‐overhead real‐time scheduler

Devising energy-efficient scheduling strategies for real-time periodic tasks on heterogeneous platforms is a challenging as well as a computationally demanding problem. This study proposes a low-overhead heuristic strategy called, HEALERS, for dynamic voltage and frequency scaling (DVFS)-cum-dynamic power management (DPM) enabled energy-aware scheduling of a set of periodic tasks executing on a heterogeneous multi-core system. The presented strategy first applies deadline-partitioning to acquire a set of distinct time-slices. At any time-slice boundary, the following three-phase operations are applied to obtain a schedule for the next time-slice: first, it computes the fragments of the execution demands of all tasks onto each of the different processing cores in the platform. Next, it generates a schedule for each task on one or more processing cores such that the total execution demand of all tasks is satisfied. Finally, HEALERS applies DVFS and DPM on all processing cores so that energy consumption within the time-slice may be minimized while not jeopardising execution requirements of the scheduled tasks. Experimental results show that the proposed scheme is not only able to achieve appreciable energy savings with respect to state-of-the-art (5–42% on average) but also enables a significant improvement in resource utilisation (as high as 58%).

Mechanical reasoning, working memory and processing speed

Background: Mechanical reasoning (MR) is the ability to identify the components of a system and understand how they interact in order for the system to work. Different mechanical systems, such as those of wheels and gears, require different types of reasoning. Objective: This study seeks to analyze the relationship that working memory (WM) and processing speed (PS) have with MR. Method: One hundred seventy-three (173) university students were assessed through the DAT test which consisted of 30 MR problems, the symbol search subtest of the WAIS-III battery for assessing the PS, and the BIMET-V and BIMET-VE batteries to evaluate the WM verbal and visuospatial components. Results: Regression analyses showed that the proposed variables do not predict the performance in gear problems, while the visuospatial WM and the PS predict the performance in wheel problems. Discussion: The results suggest that gear problems have a low executive demand as they can be solved in a fractional way, while wheel problems require to hold in memory all the components that are part of the system and, at the same time, require a higher attentional load.

Processing speed, working memory, and executive functions: Independent or inter-related predictors of general intelligence

Both working memory capacity (WMC) and processing speed (PS) have been discussed as important covariates of individual differences in intelligence. Recent results indicated that especially latencies of ERP components associated with higher-order processing (P2, N2, and P3) may share up to 80% of variance with individual differences in intelligence. WMC has a similar predictive power and thus these two processes cannot explain individual differences in intelligence independently. The current study explores in how far individual differences in executive functions (EFs) may bridge the gap between WMC and PS as predictors of intelligence. We recruited 101 participants who completed three EF tasks – one for each of the three executive functions shifting, updating, and inhibition. Additionally, we assessed participants' intelligence, WMC, and PS. Results showed that only variance of behavioral RTs consistent across manipulations in the EF tasks was related to WMC, PS, and intelligence. The variance specific to the manipulations in EF tasks was small and showed no consistent correlations with each other or with any of the three covariates. These results suggest that EF tasks capture mostly manipulation-unspecific cognitive processes. Hence, individual differences in the impairment due to additional executive processing demands cannot explain why WMC and PS are related predictors of individual differences in intelligence.

A General Analysis Framework for Soft Real-Time Tasks

Much recent work has been conducted on supporting soft real-time tasks on multiprocessors due to the multicore revolution. While most earlier works focus on the traditional sporadic task model with deterministic worst-case specification, several recent works investigate the stochastic nature of many workloads seen in practice, specifying task execution times using average-case provisioning instead of the worst case. Unfortunately, all the existing work on supporting soft real-time workloads ignores a simple practical fact that the job inter-arrival time (or task period) is also stochastic for many real-world applications. Adopting a fixed worst-case period to model all the arriving pattern is rather pessimistic and may result in significant capacity loss in practice. Based on these observations, we present a general soft real-time multiprocessor schedulability analysis framework in this paper for practical sporadic task systems specified by stochastic period and execution demand, following probability distributions. Our analysis can be generally applied to global tunable priority-based schedulers, which allow any job's priority to be changed dynamically at runtime within a priority window of constant length. We have extensively evaluated the analysis framework using a MPEG video decoding case study and simulation-based experiments. Experimental results demonstrate significant advantages of our analysis, which yields over 200 and 50 percent improvements compared to existing analysis assuming worst-case task periods in terms of schedulability and magnitude of the derived tardiness bound, respectively.

How Older Adults Cope with Cognitive Complexity and Environmental Constraints during Dual-Task Walking: The Role of Executive Function Involvement.

This cross-sectional study investigated the interactive dual-task (DT) effects of executive function demands and environmental constraints on older adults’ walking and the moderating role of habitual physical activity (PA). Locomotor performance under different environmental constraints (flat versus obstructed walking) and cognitive performance with different executive function involvement (backward counting versus random number generation) were assessed under single-task (ST) and DT conditions in 135 participants (mean age 68.1 ± 8.4). The weekly number of daily steps was measured. Reciprocal DT effects of walking on cognitive performance and of the cognitive task on gait performance were computed and submitted to analyses of covariance with age, PA level, and cognitive functioning as covariates, followed by linear regressions with PA level as predictor. Cognitive task demands and environmental constraints individually and jointly affected gait variability (p = 0.033, ηp2 = 0.08) and executive function performance (p = 0.009, ηp2 = 0.09). Physical activity level predicted a low but significant percentage of variance of DT effects on gait only in flat walking (R2 = 0.04, p = 0.027). Results suggest that older individuals may adopt variable task prioritization in dual tasking depending on the type of executive function involvement and the environmental constraints on walking. Their DT ability was slightly affected by habitual PA.

A Decision-making Model for Corrective Maintenance of Offshore Wind Turbines Considering Uncertainties

Maintenance optimization has received special attention among the wind energy research community over the past two decades. This is mainly because of the high degree of uncertainties involved in the execution of operation and maintenance (O&amp;M) activities throughout the lifecycle of wind farms. The increasing complexity in offshore maintenance execution demands applied research and brings forth a need to develop problem-specific maintenance decision-making models. In this paper, a mathematical model is proposed to assist wind farm stakeholders in making critical resource- related decisions for corrective maintenance at offshore wind farms (OWFs), considering uncertainties in turbine failure information.

Enhanced Recruitment During Executive Control Processing in Cognitively Preserved Patients With Pediatric-Onset MS.

Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to executive dysfunction; however, some patients do not demonstrate functional deficits despite showing abnormalities on structural magnetic resonance imaging (MRI). Cognitively intact adults with MS have shown enhanced activation patterns relative to healthy controls on working memory tasks. We aim to evaluate whether cognitively preserved pediatric-onset MS patients engage compensatory recruitment strategies to facilitate age-normative performance on a task of working memory. Twenty cognitively preserved patients (mean age=18.7±2.7 years; 15 female) and 20 age- and sex-matched controls (mean age=18.5±2.9 years; 15 female) underwent neuropsychological testing and 3.0 Tesla MRI, including structural and functional acquisitions. Patterns of activation during the Alphaspan task, a working memory paradigm with two levels of executive control demand, were examined via whole-brain and region of interest (ROI) analyses. Across all participants, lower accuracy and greater activation of regions implicated in working memory were observed during the high demand condition. MS patients demonstrated 0.21 s longer response time than controls. ROI analyses revealed enhanced activation for pediatric-onset MS patients relative to controls in the right middle frontal, left paracingulate, right supramarginal, and left superior parietal gyri during the low executive demand condition, over and above differences in response time. MS patients also demonstrated heightened activation in the right supramarginal gyrus in the high executive demand condition. Our findings suggest that pediatric-onset MS patients may engage compensatory recruitment strategies during working memory processing. (JINS, 2019, 25, 432-442).