An Integrated Model of Cognitive Control in Task Switching

  • Altmann E
  • Gray W
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Abstract

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. Questions about how people set, focus on, and switch among the short-term goals that govern everyday behavior are key issues in the domain of cognitive control. 1 A number of experimental paradigms touch on this kind of control—including, at different levels, puzzle solving and the psychological refractory period— but the one most closely associated with the behavior of interest here is task switching. In a procedure of particular interest here, which we term the randomized-runs procedure, the experimental participant performs a large number of trials in sequence. Each trial involves presentation of a simple stimulus—a randomly selected digit, in the most common materials—to which the participant responds by judging whether the digit is even or odd (one task) or higher or lower than five (the other task), depending on which task is currently correct. Figure 1 shows the timeline of events in this procedure. Every few trials, a task cue is presented briefly and then withdrawn, after which the participant performs that task for the subsequent run of trials, until the next cue is presented. The cues themselves are randomly selected, such that on " switch " runs, the task is switched from what it was on the previous run, whereas on " repeat " runs, the task is the same as it was on the previous run. With the task changing frequently, accurate performance depends on maintaining some kind of mental represen-tation of the task to perform now. The idea with this procedure is to distill some of the essence of the " what did I want now that I'm here? " problem associated with simple errands, for example; one sets out to fetch something, having fetched many similar things before, and the old things interfere— or one's mind simply wanders. How the system

Author-supplied keywords

  • cognitive control
  • cognitive simulation
  • episodic memory
  • executive function
  • task switching

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Authors

  • Erik M Altmann

  • Wayne D Gray

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