Executive control of task switching operations.

Abstract

In many everyday situations people must rapidly switch back and forth between two or more tasks in which they are engaged. Some theorists have proposed that such task switching requires special "central executive" mental operations of the kind reaching highest development in our species. This dissertation reviews all previous research on task switching and reports six behavioral experiments investigating these operations. Subjects were required to switch between two visual-manual tasks while various factors such as the amount of practice, the complexity of the two tasks, the interference between the two tasks, and the length of the response-to-stimulus interval were varied. Data from these experiments support a two-stage model of task switching in which subjects first shift task goals and then activate the relevant response-selection rules before beginning processing for the new task. In addition, evidence is found for possible switching-context effects on task-specific stages of processing including response selection and response verification operations.