Differential contributions of set-shifting and monitoring to dual-task interference.

It is commonly argued that complex behaviour is regulated by a number of "executive functions", which work to coordinate the operation of disparate cognitive systems in the service of an overall goal. However, the identity, roles, and interactions of specific putative executive functions remain contentious, even within widely accepted tests of executive function. The authors present two experiments that use dual-task interference to provide further support for multiple distinct executive functions and to establish the differential contributions of those functions in two relatively complex executive tasks-random generation and the Wisconsin Card Sorting Test. Results are interpreted in terms of process models of the complex executive tasks.