Multitasking across the lifespan in different task contexts.

We assessed lifespan development of multitasking in a sample of 187 individuals aged 8-82 years. Participants performed a visuo-spatial working memory (VSWM) task together with either postural control or reaction time (RT) tasks. Using criterion-referenced testing we individually adjusted difficulty levels for the VSWM task to control for single-task differences. Age-differences in single-task performances followed U-shaped patterns with young adults outperforming children and older adults. Multitasking manipulations yielded robust performance decrements in VSWM, postural control and RT tasks. Presumably due to our adjustment of VSWM challenges, costs in this task were small and similar across age groups suggesting that age-differential costs found in earlier studies largely reflected differences already present during single-task performance. Age-differences in multitasking costs for concurrent tasks depended on specific combinations. For VSWM and RT task combinations increases in RT were the smallest for children but pronounced in adults highlighting the role of cognitive control processes. Stabilogram diffusion analysis of postural control demonstrated that long-term control mechanisms were affected by concurrent VSWM demands. This interference was pronounced in older adults supporting concepts of compensation or increased cognitive involvement in sensorimotor processes at older age. Our study demonstrates how a lifespan approach can delineate the explanatory scope of models of human multitasking.

Error modulates categorization of subsecond durations in multitasking contexts.

Monitoring errors consumes limited cognitive resources and can disrupt subsequent task performance in multitasking scenarios. However, there is a dearth of empirical evidence concerning this interference with prospective estimation of time. In this study, we sought to investigate this issue through a serial multitasking experiment, employing a temporal bisection task as the primary task. We introduced two task contexts by implementing two different concurrent tasks. In one context, participants were tasked with discriminating the size difference between two visual items, while in the other context, they were required to judge the temporal order of similar visual items. The primary task remained the same for the entire experiment. Psychophysical metrics, including subjective bias (determined by the bisection point) and temporal sensitivity (measured by the Weber ratio), in addition to reaction time, remained unaltered in the primary task regardless of the perceptual context exerted by the concurrent tasks. However, commission of error in the concurrent tasks (i.e., non-specific errors) led to a right-ward shift in the bisection point, indicating underestimation of time after errors. Applying a drift-diffusion framework for temporal decision making, we observed alterations in the starting point and drift rate parameters, supporting the error-induced underestimation of time. The error-induced effects were all diminished with increasing a delay between the primary and concurrent task, indicating an adaptive response to errors at a trial level. Furthermore, the error-induced shift in the bisection point was diminished in the second half of the experiment, probably because of a decline in error significance and subsequent monitoring response. These findings indicate that non-specific errors impact the prospective estimation of time in multitasking scenarios, yet their effects can be alleviated through both local and global reallocation of cognitive resources from error processing to time processing.

Brain function complexity during dual-tasking is associated with cognitive impairment and age.

BACKGROUND AND PURPOSE: Early diagnosis of cognitive impairment is important because symptoms can be delayed through therapies. Synaptic disconnections are the key characteristics of dementia, and through nonlinear complexity analysis of brain function, it is possible to identify long-range synaptic disconnections in the brain. METHODS: We investigated the capability of a novel upper-extremity function (UEF) dual-task paradigm in the functional MRI (fMRI) setting, where the participant flexes and extends their arm while counting, to differentiate between cognitively normal (CN) and those with mild cognitive impairment (MCI). We used multiscale entropy (MSE) complexity analysis of the blood oxygen-level dependent time-series across neural networks and brain regions. Outside of the fMRI, we used the UEF dual-task test, while the elbow kinematics were measured using motion sensors, to record the motor function score. RESULTS: Results showed 34% lower MSE values in MCI compared to CN (p<.04 for all regions and networks except cerebellum when counting down by one; effect size = 1.35±0.15) and a negative correlation between MSE values and age (average r2 of 0.30 for counting down by one and 0.36 for counting backward by three). Results also showed an improvement in the logistic regression model sensitivity by 14-24% in predicting the presence of MCI when brain function measure was added to the motor function score (kinematics data). CONCLUSIONS: Current findings suggest that combining measures of neural network and motor function, in addition to neuropsychological testing, may provide an accurate tool for assessing early-stage cognitive impairment and age-related decline in cognition.

Deep Personal Multitask Prediction of Diabetes Complication with Attentive Interactions Predicting Diabetes Complications by Multitask-Learning.

Objective: Diabetic complications have brought a tremendous burden for diabetic patients, but the problem of predicting diabetic complications is still unresolved. Our aim is to explore the relationship between hemoglobin A1C (HbA1c), insulin (INS), and glucose (GLU) and diabetic complications in combination with individual factors and to effectively predict multiple complications of diabetes. Methods: This was a real-world study. Data were collected from 40,913 participants with an average age of 48 years from the Department of Endocrinology of Ruijin Hospital in Shanghai. We proposed deep personal multitask prediction of diabetes complication with attentive interactions (DPMP-DC) to predict the five complication models of diabetes, including diabetic retinopathy, diabetic nephropathy, diabetic peripheral neuropathy, diabetic foot disease, and diabetic cardiovascular disease. Results: Our model has an accuracy rate of 88.01% for diabetic retinopathy, 89.58% for diabetic nephropathy, 85.77% for diabetic neuropathy, 80.56% for diabetic foot disease, and 82.48% for diabetic cardiovascular disease. The multitasking accuracy of multiple complications is 84.67%, and the missed diagnosis rate is 9.07%. Conclusion: We put forward the method of interactive integration with individual factors of patients for the first time in diabetic complications, which reflect the differences between individuals. Our multitask model using the hard sharing mechanism provides better prediction than prior single prediction models.

Physiological stress in response to multitasking and work interruptions: Study protocol.

BACKGROUND: The biopsychological response patterns to digital stress have been sparsely investigated so far. Important potential stressors in modern working environments due to increased digitalization are multitasking and work interruptions. In this study protocol, we present a protocol for a laboratory experiment, in which we will investigate the biopsychological stress response patterns to multitasking and work interruptions. METHODS: In total, N = 192 healthy, adult participants will be assigned to six experimental conditions in a randomized order (one single-task, three dual-task (two in parallel and one as interruption), one multitasking, and one passive control condition). Salivary alpha-amylase as well as heart rate as markers for Sympathetic Nervous System Activity, heart rate variability as measure for Parasympathetic Nervous System (PNS) activity, and cortisol as measure for activity of the hypothalamic-pituitary adrenal (HPA) axis will be assessed at six time points throughout the experimental session. Furthermore, inflammatory markers (i.e., IL-6, C-reactive protein (CRP), and secretory immunoglobulin-A) will be assessed before and after the task as well as 24 hours after it (IL-6 and CRP only). Main outcomes will be the time course of these physiological stress markers. Reactivity of these measures will be compared between the experimental conditions (dual-tasking, work interruptions, and multitasking) with the control conditions (single-tasking and passive control). DISCUSSION: With this study protocol, we present a comprehensive experiment, which will enable an extensive investigation of physiological stress-responses to multitasking and work interruptions. Our planned study will contribute to a better understanding of physiological response patterns to modern (digital) stressors. Potential risks and limitations are discussed. The findings will have important implications, especially in the context of digital health in modern working and living environments.

The persistence of distraction: The hidden costs of intermittent multitasking.

We examined the hidden costs of intermittent multitasking. Participants performed a pursuit-tracking task (Experiment 1) or drove in a high-fidelity driving simulator (Experiment 2) by itself or while concurrently performing an easy or difficult backwards counting task that periodically started and stopped, creating on-task and off-task multitasking epochs. A novel application of the Detection Response Task (DRT), a standardized protocol for measuring cognitive workload (ISO 17488, 2016), was used to measure performance in the on-task and off-task intervals. We found striking costs that persisted well after the counting task had stopped. In fact, the multitasking costs dissipated as a negatively accelerated function of time with the largest costs observed immediately after multitasking ceased. Performance in the off-task interval remained above baseline levels throughout the 30-s off-task interval. We suggest that loading new procedures into working memory occurs fairly quickly, whereas purging this information from working memory takes considerably longer. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Video game and motor-cognitive dual-task training could be suitable treatments to improve dual-task interference in older adults.

The objective of study was to investigate the effects of video game training in comparison with traditional motor-cognitive dual-task training on dual-task interference in older adults. Sixty older adults were allocated to the video game (intervention group) or the motor-cognitive dual-task training (control group). The outcome measures were dual-task cost (DTC) of linear metrics (Standard deviation (SD) of amplitude and velocity) and DTC of nonlinear metrics (approximate entropy, Lyapunov and correlation dimension) acquired from postural sway time series from both the mediolateral (ML) and anteroposterior (AP) directions. The results revealed in both groups, dual-task cost of SD of amplitude and velocity as well as Lyapunov were significantly decreased in post-training and follow-up compared with pre-training (p < 0.017), while there was no significant difference between the groups. Video game and motor-cognitive dual-task training could be recommended as suitable treatments to improve dual-task interference.

Multitask learning over shared subspaces.

This paper uses constructs from machine learning to define pairs of learning tasks that either shared or did not share a common subspace. Human subjects then learnt these tasks using a feedback-based approach and we hypothesised that learning would be boosted for shared subspaces. Our findings broadly supported this hypothesis with either better performance on the second task if it shared the same subspace as the first, or positive correlations over task performance for shared subspaces. These empirical findings were compared to the behaviour of a Neural Network model trained using sequential Bayesian learning and human performance was found to be consistent with a minimal capacity variant of this model. Networks with an increased representational capacity, and networks without Bayesian learning, did not show these transfer effects. We propose that the concept of shared subspaces provides a useful framework for the experimental study of human multitask and transfer learning.

Paradigmas de ejecución dual: aspectos conceptuales / Dual performance paradigms: their conceptual aspects

Introducción: Los paradigmas de doble tarea (o tareas de ejecución dual) se hallan implicados en múltiples y variadas actividades de nuestra vida cotidiana, ya que se consideran una ventaja evolutiva de la filogenia que posibilita llevar a cabo varias tareas al mismo tiempo con una optimización ‘de los recursos neuronales’ en comparación con las tareas que, por el contrario, se realizarían como una tarea única o simple. Desarrollo: Se revisa la bibliografía relacionada con tres paradigmas de ejecución de doble tarea: a) paradigma cognitivo/motor que hace referencia a modelos, en los que se hallan implicadas una tarea con un componente cognitivo y una tarea con un componente motor; b) paradigma motor/motor que hace referencia a una tarea motora y una tarea simultánea también motora, y c) paradigma cognitivo/cognitivo, en el que se implican una tarea con un componente cognitivo y otra también cognitiva. Conclusiones: Las tareas duales son una eficiente herramienta para detectar el deterioro cognitivo leve, así como un paradigma idóneo para la intervención en rehabilitación, dado el incremento de recursos atencionales y funciones ejecutivas implicados en su ejecución. En cuanto a la neuroimagen, ésta puede aportar: a) localizar los procesos cognitivos, motores y/o perceptivos implicados en los diferentes paradigmas de ejecución dual; b) caracterizar las respuestas y función de determinadas señales cerebrales en cada una de las tareas, y c) relacionar modificaciones en la actividad neural con la eficacia de diferentes programas de intervención.(AU)

Introduction: Dual-task paradigms (or dual performance tasks) are involved in a wide variety of multiple activities in our daily lives, as they are considered an evolutionary advantage of the phylogeny that makes it possible to perform several tasks at the same time with an optimisation of the ‘neural resources’ compared to tasks that would otherwise be carried out as a single task. Development: The literature related to three dual-task performance paradigms is reviewed: a) the cognitive/motor paradigm, referring to models that involve a task with a cognitive component and a task with a motor component; b) the motor/motor paradigm, referring to a motor task and a simultaneous motor task, and c) the cognitive/cognitive paradigm, in which a task with a cognitive component and a cognitive task are involved. Conclusions: Dual tasks are an efficient tool for detecting mild cognitive impairment, as well as an ideal paradigm for rehabilitation intervention, given the increased attentional resources and executive functions involved in performing them. Neuroimaging can be a valuable tool that makes it possible to: a) locate the cognitive, motor and/or perceptual processes involved in the different dual performance paradigms; b) characterise the responses and function of specific brain signals in each of the tasks, and c) relate changes in neural activity to the efficacy of different intervention programmes.(AU)

Long-term maintenance of multitasking abilities following video game training in older adults.

The use of cognitive interventions to remediate deficient cognitive functions, or to enhance or preserve intact cognitive abilities, has been explored for some time, especially in older adults. However, few studies have investigated the long-term persistence of any positive benefits, with none examining whether changes in functional brain activity persist several years later. Here, we assessed whether enhanced cognitive abilities and potential underlying neural changes attained via the use of a custom-made video game (NeuroRacer) played by older adults (60-85 years old) continued to be elevated beyond control participants 6 years later. The NeuroRacer group continued to show reduced multitasking costs beyond control participants, with a neural signature of cognitive control, midline frontal theta power, also continuing to show heightened activity. However, previously evidenced performance benefits that had extended to untrained cognitive control abilities (i.e., enhanced sustained attention and working memory) did not persist, highlighting sustainability limitations. These findings continue to demonstrate the robust plasticity of the prefrontal cognitive control system in the aging brain, a potential neural mechanism underlying enhanced performance over time, and the possible long-term impact that digital therapeutics can have.

Adaptive rescheduling of error monitoring in multitasking.

The concurrent execution of temporally overlapping tasks leads to considerable interference between the subtasks. This also impairs control processes associated with the detection of performance errors. In the present study, we investigated how the human brain adapts to this interference between task representations in such multitasking scenarios. In Experiment 1, participants worked on a dual-tasking paradigm with partially overlapping execution of two tasks (T1 and T2), while we recorded error-related scalp potentials. The error positivity (Pe), a correlate of higher-level error evaluation, was reduced after T1 errors but occurred after a correct T2-response instead. MVPA-based and regression-based single-trial analysis revealed that the immediate Pe and deferred Pe are negatively correlated, suggesting a trial-wise trade-off between immediate and postponed error processing. Experiment 2 confirmed this finding and additionally showed that this result is not due to credit-assignment errors in which a T1 error is falsely attributed to T2. For the first time reporting a Pe that is temporally detached from its eliciting error event by a considerable amount of time, this study illustrates how reliable error detection in dual-tasking is maintained by a mechanism that adaptively schedules error processing, thus demonstrating a remarkable flexibility of the human brain when adapting to multitasking situations.

Does Hydration Status Influence Executive Function? A Systematic Review.

BACKGROUND: Cognitive function, including executive function (EF)-related capacities (eg, working memory, inhibitory and attentional control), has been linked to adherence to healthy lifestyle behaviors. Dehydration is associated with impaired cognitive function, whereas improvements in hydration status may improve inhibitory and attentional performance. No systematic reviews have examined the effects of both dehydration and euhydration on EF. OBJECTIVE: The objectives of this systematic review are to examine studies that have investigated the spectrum of hydration status and EF in adults, and to identify future research needs. DESIGN: The review was conducted according to the 2015 Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines. The database search was initially conducted on May 12, 2019 and then updated on April 26, 2020. Databases searched included PubMed, Medline, Psyc Info, SCOPUS, Proquest, and ISI Web of Science. Data extraction included the following: method used to assess de/hydration status, study design, participant characteristics, EF tasks and domain, and results. Article quality ratings were performed on included studies using the Academy of Nutrition and Dietetics Quality Rating Checklist. PARTICIPANTS/SETTING: Studies done with healthy or diseased adults, aged older than 18 years, in any setting, were included. Studies of individuals with disease states that impact fluid balance or require fluid restrictions as treatments were excluded. MAIN OUTCOME MEASURE: All EF-related outcomes were included, such as working memory, inhibitory control, task switching, and attention. RESULTS: Four thousand eight hundred thirty-three articles were screened using title/abstracts. Seventy-one full-text articles were assessed for eligibility; 33 were included (26 included investigations of dehydration; 27 included investigations of rehydration/euhydration) with 3,636 participants across all studies. Little consistency was found across outcomes. Roughly half of the available studies suggested unclear or neutral EF effects, and half suggested effects on EF domains, particularly working memory, inhibitory control, and attention. Studies including a euhydration condition were slightly more likely to demonstrate improvements to EF capacities. CONCLUSIONS: Overall, there is a strong need for consistent methodological approaches and a greater number of long-term (ie, >3 days) studies of dehydration and euhydration and EF.

Coordination between motor and cognitive tasks in dual task gait.

BACKGROUND: Dual Task (DT) paradigms are frequently used by researchers and clinicians to examine the integrity of motor processes in many movement disorders. However, the mechanism of this interaction is not fully understood. Therefore, the aim of this study was to examine the within-stride interactions between cognitive and motor processes during dual task gait (DT). RESEARCH QUESTION: Do healthy young adults coordinate gait with secondary task processing? If so, is cognitive task processing capability associated with the coordination observed? METHODS: Nineteen healthy young adults walked for two minutes on a motorized treadmill whilst counting backwards in sevens from three-digit numbers. The coordination of calculation verbalizations with gait parameters were assessed across six phases of the gait cycle. Mid verbalization time points (VERMid) were used as points of high cognitive processing of the dual task and compared with the end of the verbalizations (VEREnd) as points of low cognitive processing. RESULTS: VERMid and VEREnd did not systematically occur in any phase of the gait cycle. However, 10/19 and 9/19 participants showed non-random distributions of verbalizations for VERMid and VEREnd time points respectively (p < 0.01), indicating that these walkers coordinated gait with the cognitive task. Analysis of subgroups of Verbalization Coordinators and Non-Coordinators showed slower verbalization response durations (VRD) for VERMid Coordinators compared to VERMid Non-Coordinators, indicating that VERMid Coordinators found the cognitive tasks more demanding. No differences were found in VRD for VEREnd Coordinators and VEREnd Non-Coordinators. SIGNIFICANCE: It was found that cognitive processing is coordinated with gait phases in some but not all healthy young adults during DT gait. When demands on cognitive processes are high, healthy young adults coordinate cognitive processing with phases of gait. Analysis of within-stride coordination may be of use for studying clinical conditions where gait and attentional cognition performance breaks down.

Evaluation of Attention Switching and Duration of Electronic Inbox Work Among Primary Care Physicians.

Importance: Primary care physicians (PCPs) report multitasking during workdays while processing electronic inbox messages, but scant systematic information exists on attention switching and its correlates in the health care setting. Objectives: To describe PCPs' frequency of attention switching associated with electronic inbox work, identify potentially modifiable factors associated with attention switching and inbox work duration, and compare the relative association of attention switching and other factors with inbox work duration. Design, Setting, and Participants: This cross-sectional study of the work of 1275 PCPs in an integrated group serving 4.5 million patients used electronic health record (EHR) access logs from March 1 to 31, 2018, to evaluate PCPs' frequency of attention switching. Statistical analysis was performed from October 15, 2018, to August 28, 2020. Main Outcomes and Measures: Attention switching was defined as switching between the electronic inbox, other EHR work, and non-EHR periods. Inbox work duration included minutes spent on electronic inbox message views and related EHR tasks. Multivariable models controlled for the exposures. Results: The 1275 PCPs studied (721 women [56.5%]; mean [SD] age, 45.9 [8.5] years) had a mean (SD) of 9.0 (7.6) years of experience with the medical group and received a mean (SD) of 332.6 (148.3) (interquartile range, 252-418) new inbox messages weekly. On workdays, PCPs made a mean (SD) of 79.4 (21.8) attention switches associated with inbox work and did a mean (SD) 64.2 (18.7) minutes of inbox work over the course of 24 hours on workdays. In the model for attention switching, each additional patient secure message beyond the reference value was associated with 0.289 (95% CI, 0.217-0.362) additional switches, each additional results message was associated with 0.203 (95% CI, 0.127-0.278) additional switches, each additional request message was associated with 0.190 (95% CI, 0.124-0.257) additional switches, and each additional administrative message was associated with 0.262 (95% CI, 0.166-0.358) additional switches. Having a panel (a list of patients assigned to a primary care team) with more elderly patients (0.144 switches per percentage increase [95% CI, 0.009-0.278]) and higher inbox work duration (0.468 switches per additional minute of inbox work [95% CI, 0.411-0.524]) were also associated with higher attention switching involving the inbox. In the model for inbox work duration, each additional patient secure message beyond the reference value was associated with 0.151 (95% CI, 0.085-0.217) additional minutes, each additional results message was associated with 0.338 (95% CI, 0.272-0.404) additional minutes, each additional request message was associated with 0.101 (95% CI, 0.041-0.161) additional minutes, and each additional administrative message was associated with 0.179 (95% CI, 0.093-0.265) additional minutes. A higher percentage of the panel's patients initiating messages (0.386 minutes per percentage increase [95% CI, 0.026-0.745]) and attention switches (0.373 minutes per switch [95% CI, 0.328-0.419]) were also associated with higher inbox work duration. In addition, working at a medical center where all PCPs had high inbox work duration was independently associated with high or low inbox work duration. Conclusions and Relevance: This study suggests that PCPs make frequent attention switches during workdays while processing electronic inbox messages. Message quantity was associated with both attention switching and inbox work duration. Physician and patient panel characteristics had less association with attention switching and inbox work duration. Assisting PCPs with message quantity might help modulate both attention switching and inbox work duration.

Primary dysmenorrhea and postural control: Is it a problem only during menstruation?

BACKGROUND: The effects of the menstrual cycle and primary dysmenorrhea (PD) on phase-related cognitive and physical functions are controversial. This study was carried out to examine whether women with PD showed a different physical function or dual-tasking response than women without PD at times other than menstruation. METHODS: Women with or without PD were recruited for the study. Individuals assessed on the first day of the menstruation and the day they reported themselves as well being (feeling good day-FGD). Zebris © FDM Type Force Platform was used to evaluate postural stability. Individuals have were asked to perform to a 3-step balance test protocol; the first session: comfortable upright standing; the second session: standing with a motor task; the third session: standing with a cognitive task (counting backward). Correctly calculated numbers were also recorded. RESULTS: The number of correct answers given by individuals during the cognitive dual-task was similar on the first day of menstruation and FGD (p > 0.05). In the control group, no difference was observed between the first days of menstruation and the evaluations on FGD days with dual-task (p > 0.05). In individuals with PD, there was no difference between the measurements at different times (p > 0.05). However, in the assessment with the motor dual-task on the first day of menstruation; postural sway increased (p < 0,05). In FDG measurement; distortion in postural stability was observed with the cognitive task (p < 0,05). In the assessments performed on the first day of menstruation, there was no difference in any parameters between the groups (p > 0.05). In the measurements made on FGD day with the cognitive task; there was a difference between the groups (p < 0,05). Individuals with PD had higher postural sway. SIGNIFICANCE: This study showed that the primary dysmenorrhea is not only a problem for females during menstruation, primary dysmenorrhea causes impaired ability of the individual to perform dual-tasking and continuously affects postural stability.

The relation between task-unrelated media multitasking and task-related motivation.

In two experiments, we explored the relation between participants' (a) levels of motivation to complete a task and (b) task-unrelated media multitasking. In Experiment 1, we examined the extent to which participants' levels of motivation to complete a task influenced their tendency to engage in task-unrelated media multitasking. Participants completed a 1-back task, while having the opportunity to turn on and off an unrelated, optional video. Results showed that participants who were told they would finish the experiment early if they achieved a sufficient level of performance (the motivated group) were significantly less likely to play the optional video during the 1-back task than those who were not given the opportunity to finish early (control condition). In Experiment 2, we examined the extent to which engaging in task-unrelated media multitasking affected task-related motivation. Three groups of participants completed a 1-back task, while (a) no video was presented, (b) a video was continuously played, or (c) participants could turn on and off a video at their leisure (as in Experiment 1). At both the beginning and the end of Experiment 2, participants were asked to indicate their level of motivation to complete the task. Interestingly, results revealed that continuously having the video playing helped sustain task-related motivation. Thus, although greater motivation to perform a task reduces the likelihood of engaging in task-unrelated media multitasking, such media multitasking also appears to increase levels of motivation.

Spatial-Temporal Parameters of Gait Associated With Alzheimer Disease: A Longitudinal Analysis.

Alzheimer's disease (AD) is one of the biggest social and medical concerns in the aging world. A dual task of walking and talking is a particularly practical means to assess AD considering the cognitive and behavioral changes that characterize the disease. The purpose of the study was to assess the effect of the dual task of walking and talking on people with early stage AD under differing cognitive load levels of talking. Participants (9 women and 5 men, mean age (years) = 78.03, standard deviation [SD] = 12.06) with mild or moderate AD (mean Dementia Rating Scale 2 score = 88.14, SD = 7.07) completed 12 monthly walking sessions under no, low, or high cognitive load. They also completed the low and high cognitive load tasks while seated. Linear mixed-effects modeling revealed that values in the Functional Ambulation Profile, stride length, and velocity decreased as tasks became more complex and double support time increased at the same rate. The walking and seated conditions comparison indicated that participants' performance on both low and high cognitive tasks was poor when they were walking rather than seated. The results show that people with early stage AD exhibited gait impairments that increased over time and when completing tasks with greater cognitive load.

Incremental validity of placekeeping as a predictor of multitasking.

Multitasking is ubiquitous in everyday life, which means there is value in developing measures that predict successful multitasking performance. In a large sample (N = 404 contributing data), we examined the predictive and incremental validity of placekeeping, which is the ability to perform a sequence of operations in a certain order without omissions or repetitions. In the context of multitasking, placekeeping should play a role in the performance of procedural subtasks and the interleaving of subtasks that interrupt each other. Regression analyses revealed that placekeeping ability accounted for 11% of the variance in multitasking performance, and had incremental validity relative to each of a diverse set of cognitive abilities (working memory capacity, fluid intelligence, perceptual speed, and crystallized intelligence). The predictive validity of placekeeping for multitasking was stable across samples of performance and robust to placekeeping practice. Broader measures of performance on our placekeeping task accounted for 21% of the variance in multitasking performance and had incremental validity relative to an estimate of psychometric g. The results provide evidence that placekeeping is a distinct cognitive ability with its own specific role to play in multitasking, and raise the possibility that measures of placekeeping ability could have utility in selecting personnel for occupations that require certain kinds of multitasking, such as interleaving of procedures.

Neurophysiological correlates of age differences in driving behavior during concurrent subtask performance.

Driving is a complex cognitive-motor task that requires the continuous integration of multisensory information, cognitive processes, and motor actions. With higher age, driving becomes increasingly challenging as a result of naturally declining neurophysiological resources. Performing additional subtasks, such as conversations with passengers or interactions with in-vehicle devices (e.g., adjusting the radio), may further challenge neurocognitive resources that are required to maintain driving performance. Based on declining brain physiological resources and inferior neurocognitive functioning, older adults (OA) may show higher brain activation and larger performance decrements than younger adults (YA) when engaging in additional subtasks during driving. Age differences, however, may further vary for different neurocognitive task demands, such that driving performance of OA might be particularly affected by certain subtasks. In this study, we hence investigated the brain functional correlates of age differences in driving behavior during concurrent subtask performance in YA and OA. Our final sample consisted of thirty younger (21.80 ± 1.73y, 15 female) and thirty older (69.43 ± 3.30y, 12 female) regular drivers that drove along a typical rural road (25 - 30 min) in a driving simulator and performed three different concurrent subtasks that were presented auditorily or visually: typing a 3-digit number (TYPE), comparing traffic news and gas station prices (working memory, WM), and stating arguments (ARG). We measured variability in lateral car position, velocity, and following distance to a frontal lead car as the standard deviation from 0 to 15 s after subtask onset. Brain activity was continuously recorded using functional near-infrared spectroscopy over the dorsolateral prefrontal cortex. Both YA and OA particularly varied in their lateral position during TYPE with a more pronounced effect in OA. For YA, in contrast, ARG led to higher variability in velocity compared to TYPE and WM, whereas OA showed no task-specific differences. Substantiating our behavioral findings, OA revealed the largest brain functional response to TYPE, while YA demonstrated a very distinct activation during ARG and smaller hemodynamic responses to TYPE and WM. Brain activity in the DLPFC was, overall, not significantly, but small to moderately related to certain behavioral performance parameters (mainly lateral position). We conclude that both OA and YA are vulnerable to distractive subtasks while driving. Age differences, however, seem to largely depend on neurocognitive task demands. OA may be at higher risk for accidents when performing visuo-motor subtasks (e.g., interacting with navigational systems) during driving while YA may be more (cognitively) distracted when talking to passengers.

Front Desk Duty Multitasking Test After Mild Stroke: Preliminary Reliability and Validity.

BACKGROUND.: Performance-based multitasking assessments may be more sensitive than cognitive screens to detect executive dysfunction after a mild stroke. PURPOSE.: This cross-sectional study examined inter-rater reliability and preliminary convergent and discriminant validity of the Front Desk Duty Test (FDDT). METHOD.: Adults with mild stroke (n = 35) and community controls (n = 33) were administered the FDDT and other measures of executive functions. FINDINGS.: Inter-rater reliability of the FDDT subscores were high (ICC 0.971-0.999). There were weak but statistically significant correlations between participants' scores on some of the executive function tests and some FDDT subscores. Participants with mild stroke and community controls had statistically significant different FDDT scores (performance accuracy p = .006; performance time, p = .033), with rank order FDDT score patterns across community controls, participants with mild stroke who passed the executive function screen, and participants with mild stroke who failed the executive function screen. IMPLICATIONS.: Preliminary validation results suggest that the FDDT warrants further study.