Generic cognitive adaptations to task interference in task switching

Task intentions and their implementation into actions: cognitive control from adolescence to middle adulthood

Cognitive control processes involved in human multitasking arise, mature, and decline across age. This study investigated how age modulates cognitive control at two different levels: the level of task intentions and the level of the implementation of intentions into the corresponding actions. We were particularly interested in specifying maturation of voluntary task choice (intentions) and task-switching execution (their implementations) between adolescence and middle adulthood. Seventy-four participants were assigned to one of the four age groups (adolescents, 12-17 years; emerging adults, 18-22 years; young adults, 23-27 years; middle-aged adults, 28-56 years). Participants chose between two simple cognitive tasks at the beginning of each trial before pressing a spacebar to indicate that the task choice was made. Next, a stimulus was presented in one of the three adjacent boxes, with participants identifying either the location or the shape of the stimulus, depending on their task choice. This voluntary task-switching paradigm allowed us to investigate the intentional component (task choice) separately from its implementation (task execution). Although all participants showed a tendency to repeat tasks more often than switching between them, this repetition bias was significantly stronger in adolescents than in any adult group. Furthermore, participants generally responded slower after task switches than after task repetitions. This switch cost was similar across tasks in the two younger groups but larger for the shape than the location task in the two older groups. Together, our results demonstrate that both task intentions and their implementation into actions differ across age in quite specific ways.

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 In this procedure, a task cue is presented at the start of a run of trials and then withdrawn, such that the task has to be stored in memory to guide performance until the next task cue is presented.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.

Corresponding influences of top-down control on task switching and long-term memory

Three experiments investigated the impact of cognitive control on current performance and later memory in task switching. Participants first switched between object and word classification tasks, performed on picture-word stimuli that each appeared only once, then were tested for their recognition memory of these items. Each experiment replicated the recent finding that task switching results in reduced selectivity in later memory for task-relevant over task-irrelevant items. Top-down control was manipulated through varying the time available for advance task preparation (Experiment 1), the freedom of choice over which task to perform (Experiment 2), and the availability of reward incentives (Experiment 3). For each manipulation, more effective top-down control during task switching was associated with increased selectivity in memory for task-relevant information. These findings shed new light on the role of cognitive control in long-term memory encoding, in particular supporting an interactive model in which long-term memory reflects the enduring traces of perceptual and cognitive processes that operate under the selective influence of top-down control.