Activation of multiple-demand regions during diverse difficult tasks has led to the recognition of domain-general demands that arise during any difficult task. Our tasks, however, are temporally structured episodes made of multiple components that are controlled as a single unit toward an overarching goal. Their numerous component control processes are organized through a goal-directed program instated at the episode's onset. Difficult task episodes that require complex control processes also require a complex program to organize and coordinate them over time. Across four different fMRI experiments with different task designs and contents, we found that instituting these programs at the beginning of extended episodes involves a categorically different domain-general demand from that needed during their subsequent execution. This demand deactivated widespread regions, including the very same multiple-demand regions that activate during the execution of difficult tasks. The distinction between the demands related to program instatement versus those related to control during execution extended to psychophysiological signatures. In a fifth experiment, pupil diameter-typically increasing with control processes-decreased when more demanding programs were being instated. Instating overarching programs at the beginning of extended tasks thus constitutes a unique cognitive demand, distinct from the control processes engaged during task performance.
Gezici et al. (Wed,) studied this question.