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.

Response-cue interval effects in extended-runs task switching: memory, or monitoring?

This study investigated effects of manipulating the response-cue interval (RCI) in the extended-runs task-switching procedure. In this procedure, a task cue is presented at the start of a run of trials and then withdrawn, such that the task has to be stored in memory to guide performance until the next task cue is presented. The effects of the RCI manipulation were not as predicted by an existing model of memory processes in task switching (Altmann and Gray, Psychol Rev 115:602-639, 2008), suggesting that either the model is incorrect or the RCI manipulation did not have the intended effect. The manipulation did produce a theoretically meaningful pattern, in the form of a main effect on response time that was not accompanied by a similar effect on the error rate. This pattern, which replicated across two experiments, is interpreted here in terms of a process that monitors for the next task cue, with a longer RCI acting as a stronger signal that a cue is about to appear. The results have implications for the human factors of dynamic task environments in which critical events occur unpredictably.

Explaining the Validity of the ASVAB for Job-Relevant Multitasking Performance: The Role of Placekeeping Ability.

Scores on the Armed Services Vocational Aptitude Battery (ASVAB) predict military job (and training) performance better than any single variable so far identified. However, it remains unclear what factors explain this predictive relationship. Here, we investigated the contributions of fluid intelligence (Gf) and two executive functions-placekeeping ability and attention control-to the relationship between the Armed Forces Qualification Test (AFQT) score from the ASVAB and job-relevant multitasking performance. Psychometric network analyses revealed that Gf and placekeeping ability independently contributed to and largely explained the AFQT-multitasking performance relationship. The contribution of attention control to this relationship was negligible. However, attention control did relate positively and significantly to Gf and placekeeping ability, consistent with the hypothesis that it is a cognitive "primitive" underlying the individual differences in higher-level cognition. Finally, hierarchical regression analyses revealed stronger evidence for the incremental validity of Gf and placekeeping ability in the prediction of multitasking performance than for the incremental validity of attention control. The results shed light on factors that may underlie the predictive validity of global measures of cognitive ability and suggest how the ASVAB might be augmented to improve its predictive validity.

When the rules are reversed: action-monitoring consequences of reversing stimulus-response mappings.

How does switching tasks affect our ability to monitor and adapt our behavior? Largely independent lines of research have examined how individuals monitor their actions and adjust to errors, on the one hand, and how they are able to switch between two or more tasks, on the other. Few studies, however, have explored how these two aspects of cognitive-behavioral flexibility interact. That is, how individuals monitor their actions when task rules are switched remains unknown. The present study sought to address this question by examining the action-monitoring consequences of response switching-a form of task switching that involves switching the response that is associated with a particular stimulus. We recorded event-related brain potentials (ERPs) while participants performed a modified letter flanker task in which the stimulus-response (S-R) mappings were reversed between blocks. Specifically, we examined three ERPs-the N2, the error-related negativity (ERN), and the error positivity (Pe)-that have been closely associated with action monitoring. The findings revealed that S-R reversal blocks were associated with dynamic alterations of action-monitoring brain activity: the N2 and ERN were enhanced, whereas the Pe was reduced. Moreover, participants were less likely to adapt their posterror behavior in S-R reversal blocks. Taken together, these data suggest that response switching results in early enhancements of effortful control mechanisms (N2 and ERN) at the expense of reductions in later response evaluation processes (Pe). Thus, when rules change, our attempts at control are accompanied by less attention to our actions.

Task independence of placekeeping as a cognitive control construct: Evidence from individual differences and experimental effects.

Many cognitive tasks have what we refer to as a placekeeping requirement: steps or subtasks must be performed in a linear or other systematic fashion, without repetitions or omissions that would compromise performance. Here we asked whether the cognitive control mechanisms that meet this requirement are specific to individual tasks or general enough to be shared across tasks. Participants (N = 289) performed two tasks (Letterwheel and UNRAVEL) that share a sequential structure but are otherwise distinct. Placekeeping measures correlated significantly across tasks after controlling for construct-irrelevant variance, evidence that individual differences in placekeeping ability correlated across tasks rather than varying independently. Furthermore, an empirical pattern in the form of a crossover interaction in placekeeping error gradients was evident for both tasks, evidence that placekeeping in the two tasks is supported by similar cognitive mechanisms. The results suggest that placekeeping ability is a task-independent cognitive control construct and that placekeeping measures could help predict performance in a range of workplace and everyday tasks.

Slow-wave sleep during a brief nap is related to reduced cognitive deficits during sleep deprivation.

Sleeping for a short period (i.e. napping) may help mitigate impairments in cognitive processing caused by sleep deprivation, but there is limited research on effects of brief naps in particular. Here, we tested the effect of a brief nap opportunity (30- or 60-min) during a period of sleep deprivation on two cognitive processes with broad scope, placekeeping and vigilant attention. In the evening, participants (N = 280) completed a placekeeping task (UNRAVEL) and a vigilant attention task (Psychomotor Vigilance Task [PVT]) and were randomly assigned to either stay awake overnight or sleep at home. Sleep-deprived participants were randomly assigned to receive either no nap opportunity, a 30-min opportunity, or a 60-min opportunity. Participants who napped were set up with polysomnography. The next morning, sleep participants returned, and all participants completed UNRAVEL and the PVT. Sleep deprivation impaired performance on both tasks, but nap opportunity did not reduce the impairment, suggesting that naps longer than those tested may be necessary to cause group differences. However, in participants who napped, more time spent in slow-wave sleep (SWS) was associated with reduced performance deficits on both tasks, effects we interpret in terms of the role of SWS in alleviating sleep pressure and facilitating memory consolidation.

Caffeine selectively mitigates cognitive deficits caused by sleep deprivation.

Sleep deprivation impairs a wide range of cognitive processes, but the precise mechanism underlying these deficits is unclear. One prominent proposal is that sleep deprivation impairs vigilant attention, and that impairments in vigilant attention cause impairments in cognitive tasks that require attention. Here, we test this theory by studying the effects of caffeine on visual vigilant attention and on placekeeping, a cognitive control process that plays a role in procedural performance, problem solving, and other higher order tasks. In the evening, participants (N = 276) completed a placekeeping task (UNRAVEL) and a vigilant attention task (the Psychomotor Vigilance Task [PVT]) and were then randomly assigned to either stay awake overnight in the laboratory or sleep at home. In the morning, participants who slept returned to the lab, and all participants consumed a capsule that contained either 200 mg of caffeine or placebo. After an absorption period, all participants completed UNRAVEL and PVT again. Sleep deprivation impaired performance on both tasks, replicating previous work. Caffeine counteracted this impairment in vigilant attention but did not significantly affect placekeeping for most participants, though it did reduce the number of sleep-deprived participants who failed to maintain criterion accuracy. These results suggest that sleep deprivation impairs placekeeping directly through a causal pathway that does not include visual vigilant attention, a finding that has implications for intervention research and suggests that caffeine has limited potential to reduce procedural error rates in occupational settings. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Effects of total sleep deprivation on procedural placekeeping: More than just lapses of attention.

Total sleep deprivation (TSD) impairs attention as well as higher-order cognitive processes. Because attention is a core component of many tasks, it may fully mediate the effect of sleep deprivation on higher-order processes. We examined this possibility using the Psychomotor Vigilance Task as a measure of attention and the UNRAVEL task as a measure of placekeeping, a higher-order process that involves memory operations and supports performance in a wide range of complex tasks. A large sample of participants (N = 138 contributing data) performed the Psychomotor Vigilance Task and UNRAVEL under rested or sleep-deprived conditions. TSD impaired placekeeping generally and memory maintenance processes specifically, above and beyond the effect of participants' attentional state. The results suggest that TSD may impair a range of higher-order cognitive processes directly, not just fundamental processes such as attention, and that interventions that benefit attention may have limited scope. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Is working memory capacity a causal factor in fluid intelligence?

It is well established that measures of reasoning ability and of working memory capacity (WMC) correlate positively. However, the question of what explains this relationship remains open. The purpose of this study was to investigate the capacity hypothesis, which ascribes causality to WMC. This hypothesis holds that people high in WMC are more successful in capacity-demanding cognitive tasks than people lower in WMC because they can temporarily maintain more information in the form of sub-goals, hypotheses, and partial solutions. Accordingly, this hypothesis predicts that the correlation between WMC and reasoning performance should increase as the capacity demands of the reasoning items increase. We tested this prediction using items from Raven's Progressive Matrices and two measures of WMC, complex span and the k estimate from the Visual Arrays task. Neither WMC measure showed the effect predicted by the capacity hypothesis. Furthermore, the results cannot be attributed to restriction of range in performance on the individual reasoning items. This finding adds to existing evidence calling into question the capacity hypothesis, and, more generally, the view that WMC has a causal influence on fluid intelligence.

Effects of sleep deprivation on procedural errors.

In a large sample (N = 234), we tested effects of 24-hr of sleep deprivation on error rates in a procedural task that requires memory maintenance of task-relevant information. In the evening, participants completed the task under double-blind conditions and then either stayed awake in the lab overnight or slept at home. In the morning, participants completed the task again. Sleep-deprived participants were more likely to suffer a general breakdown in ability (or willingness) to meet a modest accuracy criterion they had met the night before. Among sleep-deprived participants who could still perform the task, error rates were elevated, and errors reflecting memory failures increased with time-on-task. The results suggest that sleep-deprived individuals should not perform procedural tasks associated with interruptions and costly errors-or, if they must, they should perform such tasks only for short periods. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An integrated model of cognitive control in task switching.

A model of cognitive control in task switching is developed in which controlled performance depends on the system maintaining access to a code in episodic memory representing the most recently cued task. The main constraint on access to the current task code is proactive interference from old task codes. This interference and the mechanisms that contend with it reproduce a wide range of behavioral phenomena when simulated, including well-known task-switching effects, such as latency and error switch costs, and effects on which other theories are silent, such as with-run slowing and within-run error increase. The model generalizes across multiple task-switching procedures, suggesting that episodic task codes play an important role in keeping the cognitive system focused under a variety of performance constraints.

No Evidence That Sleep Deprivation Effects and the Vigilance Decrement Are Functionally Equivalent: Comment on Veksler and Gunzelmann (2017).

Veksler and Gunzelmann (2017) make an extraordinary claim, which is that sleep deprivation effects and the vigilance decrement are functionally equivalent. Extraordinary claims require extraordinary evidence, which is missing from Veksler and Gunzelmann's study. Their behavioral data offer only weak theoretical constraint, and to the extent their modeling exercise supports any position, it is that these two performance impairments involve functionally distinct underlying mechanisms.

Cue-independent task-specific representations in task switching: evidence from backward inhibition.

The compound-cue model of cognitive control in task switching explains switch cost in terms of a switch of task cues rather than of a switch of tasks. The present study asked whether the model generalizes to Lag 2 repetition cost (also known as backward inhibition), a related effect in which the switch from B to A in ABA task sequences is costlier than is the same switch in CBA task sequences. The model suggests that Lag 2 repetition cost should be absent from A'BA task sequences, in which A' and A are different cues for the same task. The cost is robust on such sequences, which suggests that cue-independent, task-specific representations are necessary for explaining task-switching performance and that the compound-cue model has limited explanatory power.

Comparing switch costs: alternating runs and explicit cuing.

The task-switching literature routinely conflates different operational definitions of switch cost, its predominant behavioral measure. This article is an attempt to draw attention to differences between the two most common definitions, alternating-runs switch cost (ARS) and explicit-cuing switch cost (ECS). ARS appears to include both the costs of switching tasks and the switch-independent costs specific to the first trial of a run, with the implication that it should generally be larger than ECS, but worse is that the alternating-runs procedure does not allow these costs to be separated. New data are presented to make these issues concrete, existing data are surveyed for evidence that ARS is larger than ECS, and implications of conflating these measures are examined for existing theoretical constructs.

Timecourse of recovery from task interruption: data and a model.

Interruption of a complex cognitive task can entail, for the "interruptee", a sense of having to recover afterward. We examined this recovery process by measuring the timecourse of responses following an interruption, sampling over 13,000 interruptions to obtain stable data. Response times dropped in a smooth curvilinear pattern for the first 10 responses (15 sec or so) of postinterruption performance. We explain this pattern in terms of the cognitive system retrieving a displaced mental context from memory incrementally, with each retrieved element adding to the set of primes facilitating the next retrieval. The model explains a learning effect in our data in which the timecourse of recovery changes over blocks, and is generally consistent with current representational theories of expertise.

Practice increases procedural errors after task interruption.

Positive effects of practice are ubiquitous in human performance, but a finding from memory research suggests that negative effects are possible also. The finding is that memory for items on a list depends on the time interval between item presentations. This finding predicts a negative effect of practice on procedural performance under conditions of task interruption. As steps of a procedure are performed more quickly, memory for past performance should become less accurate, increasing the rate of skipped or repeated steps after an interruption. We found this effect, with practice generally improving speed and accuracy, but impairing accuracy after interruptions. The results show that positive effects of practice can interact with architectural constraints on episodic memory to have negative effects on performance. In practical terms, the results suggest that practice can be a risk factor for procedural errors in task environments with a high incidence of task interruption. (PsycINFO Database Record

Effects of interruption length on procedural errors.

We investigated effects of task interruption on procedural performance, focusing on the effect of interruption length on the rates of different categories of error at the point of task resumption. Interruption length affected errors involving loss of place in the procedure (sequence errors) but not errors involving incorrect execution of a correct step (nonsequence errors), implicating memory for past performance, rather than generalized attentional resources, as the disrupted cognitive process. Within the category of sequence errors, interruption length produced a complex pattern of effects, with repetitions of the preinterruption step showing different effects than errors at other offsets from the correct step. A cognitive model we developed previously accounts for the results in terms of decay and rehearsal of memory for past performance and activation spreading through a procedural representation of task knowledge. The model links different types of errors to different cognitive processes, informs potential interventions, and predicts interruption effects for sequential tasks like problem solving and counting. (PsycINFO Database Record

Task switching is not cue switching.

With the aim of reducing cognitive control in task switching to simpler processes, researchers have proposed in a series of recent studies that there is little more to switching tasks than switching cues. The present study addresses three questions concerning this reduction hypothesis. First, does switching cues account for all relevant variance associated with switching tasks? Second, how well does this hypothesis generalize beyond the experimental procedure from which it was developed? Third, how well does this new procedure preserve relevant measures such as task-switch cost? The answers (no; not very; not very) suggest that task switching does not reduce to cue switching.