A computational theory of executive cognitive processes and multiple-task performance .1. Basic mechanisms

A new theoretical framework, executive-process interactive control (EPIC),is introduced for characterizing human performance of concurrent perceptual-motor and cognitive tasks. On the basis of EPIC, computational models may be formulated to simulate multiple-task performance under a variety of circumstances. These models account well for reaction-time data from representative situations such as the psychological refractory-period procedure. EPIC's goodness of fit supports several key conclusions: (a) At a cognitive level, people can apply distinct sets of production rules simultaneously for executing the procedures of multiple tasks; (b) people's capacity to process information at ''peripheral'' perceptual-motor levels is limited; (c) to cope with such Limits and to satisfy task priorities, flexible scheduling strategies are used; and (d) these strategies are mediated by executive cognitive processes that coordinate concurrent tasks adaptively.