Cognitive Control In Task Switching Research Articles

The impact of food stimuli and fasting on cognitive control in task switching.

Previous research demonstrated motivation-control interactions in task switching. However, motivational effects on switch costs have been mostly examined using monetary rewards. Here, we investigated whether stimulus material linked to food and fasting affect control processes in task switching. We predicted that switching to the task comprising food stimuli would be facilitated, which should result in lower switch costs for this task, and that these effects would be stronger with higher motivational salience of the food stimuli, i.e. in hungry individuals and/or individuals with restrictive eating. Participants switched between categorising food items as sweet or savoury and digits as odd or even in two task-switching paradigms: an alternating runs and a voluntary task switching. Hunger was induced by 14h fasting in the experimental compared to the control group. Results showed lower switch costs for the motivational-affective food task in both task-switching paradigms and in both groups. Switch costs for the neutral digit task were significantly higher in the fasting group compared to the control group in alternating runs task switching only. Individual differences in restrictive eating were related negatively but not significantly to the size of the switch costs. All in all, the results demonstrate an impact of motivational-affective stimuli on cognitive control in task switching and suggest a potential modulatory role of motivational states, though the findings need to be replicated.

Erasing the Homunculus as an Ongoing Mission: A Reply to the Commentaries.

In our recent article (Schmidt, Liefooghe, & De Houwer, 2020, this volume), we presented an adaptation of the Parallel Episodic Processing (PEP) model for simulating instruction following and task-switching behaviour. In this paper, we respond to five commentaries on our article: Monsell & McLaren (2020), Koch & Lavric (2020), Meiran (2020), Longman (2020), and Pfeuffer (2020). The commentaries discuss potential future modelling goals, deeper reflections on cognitive control, and some potential challenges for our theoretical perspective and associated model. We focus primarily on the latter. In particular, we clarify that we (a) acknowledge the role of cognitive control in task switching, and (b) are arguing that certain task-switching effects do not serve as a good measure of said cognitive control. We also discuss some ambiguities in terminological uses (e.g., the meaning of “task-set reconfiguration”), along with some future experimental and modelling research directions.

Influences of Postural Control on Cognitive Control in Task Switching.

The aim of the current study was to investigate the effects of postural control demands on cognitive control processes in concurrent auditory-manual task switching. To this end, two experiments were conducted using an auditory cued task-switching paradigm with different postural control demands (sitting vs. standing). This design allowed us to explore the effect of postural control on switch costs, mixing costs, and the between-task congruency effect. In addition, we varied the cue-based task preparation in Experiment 1 to examine whether preparation processes are independent of additional postural control demands or if the motor control processes required by the postural control demands interfere with task-specific cognitive preparation processes. The results show that we replicated the standard effects in task switching, such as switch costs, mixing costs, and congruency effects in both experiments as well as a preparation-based reduction of these costs in Experiment 1. Importantly, we demonstrated a selective effect of postural control demands in task switching in terms of an increased congruency effect when standing as compared to sitting. This finding suggests that particularly in situations that require keeping two tasks active in parallel, the postural control demands have an influence on the degree to which cognitive control enforces a more serial (shielded) mode or a somewhat less selective attention mode that allows for more parallel processing of concurrently held active task rules.

Language and cognitive control networks in bilinguals and monolinguals

Neuroimaging studies have reported overlapping neural circuits for cognitive control when engaging in tasks that involve verbal and nonverbal stimuli in young adult bilinguals. However, no study to date has examined the neural basis of verbal and nonverbal task switching in both monolinguals and bilinguals due to the inherent challenge of testing verbal task switching with monolinguals. Therefore, it is not clear whether the finding for overlapping networks is unique to bilingualism or indicative of general cognitive control. To address this question, the current study compared functional neural activation for young adults who were bilingual speakers of English and French or monolingual English speakers who had limited French learning experience (“functional monolinguals”) on verbal and nonverbal task switching. Analyses showed common variance explaining general cognitive control in task switching across verbal and nonverbal domains for both groups, in line with the explanation that task switching involves general cognitive control, as well as unique brain regions recruited by monolinguals and bilinguals. Specifically, beyond the processing common to the tasks, monolinguals also recruited distinct networks for each of verbal and nonverbal switching but bilinguals used a common shared network. Thus, the domain-general aspect of switching is different for monolinguals and bilinguals.

Modality-specific preparatory influences on the flexibility of cognitive control in task switching

ABSTRACTIn the current study, we addressed modality-specificity of the flexibility of cognitive control. We compared performance in single-task and mixed-tasks blocks between blocked auditory and visual stimuli assessing alternation costs (single vs. mixed). Mixed blocks comprised task switches only. The tasks consisted of numerical parity, magnitude, and distance judgments about numbers between one and nine without five. A cue indicated the relevant task. The cue–stimulus interval was varied (short vs. long interval) to examine preparation effects. The results indicated higher response times (RTs) and error rates (ERs) in mixed- vs. single-tasks blocks. The alternation costs in ERs were larger for auditory compared to visual stimulus presentation. Moreover, the reduction of RT alternation costs based on increased preparation time was more pronounced for the auditory modality compared to the visual modality. These results suggest a modality-specific influence on processes involved in maintaining and updating task sets in working memory.

Phasic alertness and residual switch costs in task switching.

Residual switch costs are deficits in task-switching performance that occur despite considerable time to prepare for a task switch. In the present study, the author investigated whether increased phasic alertness modulates residual switch costs. In 2 experiments involving the task-cuing procedure, subjects performed numerical categorization tasks on target digits, with and without an alerting stimulus presented shortly before the target (alert and no-alert trials, respectively). Switch costs were obtained that decreased with a longer cue-target interval, indicating subjects engaged in preparation, but large residual switch costs remained. Alerting effects were obtained in the form of faster overall performance on alert than on no-alert trials, indicating the alerting stimuli increased phasic alertness. Critically, residual switch costs were similar on alert and no-alert trials in both experiments, unaffected by manipulations of alert type, alert availability, and alert-target interval. Implications of the results for understanding the relationship between phasic alertness and cognitive control in task switching are discussed. (PsycINFO Database Record

The Bilingual Cognitive Control Mechanism of Highly Proficient Cantonese-Mandarin Speakers: Evidence from A Dual-task Switching Paradigm

实验采用双任务切换范式，考察熟练粤-普双言被试在简单情境和混合情境下任务切换和语码切换的代价模式。实验1在语音相似条件下，考察了粤-普双言者语码切换代价与任务切换代价；实验2在语音不相似条件下，探讨粤-普双言者语码切换代价与任务切换代价。结果发现，不同语音条件下，熟练粤语-普通话双言者出现对称的语码切换代价，切换过程受到语音相似性的影响，但是语码切换代价却没有受到影响，支持了特定语言选择假设。无论在何种语音条件下，任务切换代价模式和语码切换代价模式都是一致的，出现对称的切换代价，但两种切换代价相关不显著。从定性和定量结果来看，双言认知控制机制与一般认知控制机制有密切关系，但双言认知控制机制不完全附属于一般认知控制机制，双言认知控制机制可能存在一部分加工独立于一般认知控制。

A neural network model of individual differences in task switching abilities

We use a biologically grounded neural network model to investigate the brain mechanisms underlying individual differences specific to the selection and instantiation of representations that exert cognitive control in task switching. Existing computational models of task switching do not focus on individual differences and so cannot explain why task switching abilities are separable from other executive function (EF) abilities (such as response inhibition). We explore hypotheses regarding neural mechanisms underlying the “Shifting-Specific” and “Common EF” components of EF proposed in the Unity/Diversity model (Miyake & Friedman, 2012) and similar components in related theoretical frameworks. We do so by adapting a well-developed neural network model of working memory (Prefrontal cortex, Basal ganglia Working Memory or PBWM; Hazy, Frank, & O’Reilly, 2007) to task switching and the Stroop task, and comparing its behavior on those tasks under a variety of individual difference manipulations. Results are consistent with the hypotheses that variation specific to task switching (i.e., Shifting-Specific) may be related to uncontrolled, automatic persistence of goal representations, whereas variation general to multiple EFs (i.e., Common EF) may be related to the strength of PFC representations and their effect on processing in the remainder of the cognitive system. Moreover, increasing signal to noise ratio in PFC, theoretically tied to levels of tonic dopamine and a genetic polymorphism in the COMT gene, reduced Stroop interference but increased switch costs. This stability–flexibility tradeoff provides an explanation for why these two EF components sometimes show opposing correlations with other variables such as attention problems and self-restraint.

Memory and Cognitive Control in Task Switching

Cognitive control and memory are fundamentally intertwined, but interactions between the two have only recently received sustained research interest. In the study reported here, we used a novel paradigm to investigate how control influences memory encoding and, conversely, how memory measures can provide new insight into flexible cognitive control. Participants switched between classifying objects and words, then were tested for their recognition memory of items presented in this task-switching phase. Task switching impaired memory for task-relevant information but actually improved memory for task-irrelevant information, which indicates that control demands reduced the selectivity of memory encoding rather than causing a general memory decline. Recognition memory strength provided a robust trial-by-trial measure of the effectiveness of cognitive control that “predicted” earlier task-switching performance. It also revealed a substantial influence of bottom-up factors on between-task competition, but only on trials in which participants had to switch from one type of classification to the other. Collectively, our findings illustrate how cognitive control and bottom-up factors interact to simultaneously influence both current performance and future memory.

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.

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.

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.

Between-Task Competition and Cognitive Control in Task Switching

Cognitive control is required to regulate interactions between brain regions to produce effective, purposeful behavior. We used functional magnetic resonance imaging to investigate the nature of these interactions and the role of prefrontal cortex (PFC) in cognitive control as subjects switched between simple face and word categorization tasks. Face and word stimuli were used because previous research has shown them to activate distinguishable cortical regions, allowing us to measure levels of activity in task-selective brain regions during task switching. We found that activity in brain regions selective for the currently irrelevant task predicted the behavioral cost associated with switching tasks. This finding supports the theory that between-task competition is a critical determinant of behavior. Task switching was also associated with increased activity in a network of regions implicated in cognitive control, including lateral PFC and parietal cortex. Within this network of regions, we observed dissociations between task-selective and general purpose mechanisms. These findings provide support for theories that propose a control hierarchy comprising regions responsible for maintaining task-specific information about rules or goals, and regions involved in the coordination of these goals.

Modelling cognitive control in task switching and ageing

Modelling cognitive control in task switching and ageing

Modelling cognitive control in task switching and ageing

In an attempt to better understand the reasons for old-age effects on task switching performance, we fitted a quantitative model (Meiran, 2000a) to results from an experiment comparing young and elderly participants. Modelling results indicate that the most pronounced effect of old age was in what can be broadly defined as the duration of the response selection. In addition, compared to young participants, the elderly tended to rely on learning from the preceding trial, which improved their performance in single-task conditions but impaired it when the tasks switched frequently. Relatively modest effects of old age were found in the ability to selectively attend to the task relevant stimulus dimension and on the duration of processing stages preceding or following response selection.

Modeling cognitive control in task-switching.

This article describes a quantitative model, which suggests what the underlying mechanisms of cognitive control in a particular task-switching paradigm are, with relevance to task-switching performance in general. It is suggested that participants dynamically control response accuracy by selective attention, in the particular paradigm being used, by controlling stimulus representation. They are less efficient in dynamically controlling response representation. The model fits reasonably well the pattern of reaction time results concerning task switching, congruency, cue-target interval and response-repetition in a mixed task condition, as well as the differences between mixed task and pure task conditions.