Task-set inhibition in chunked task sequences.

Exploring the hierarchical control relationship between different levels of representation and processing is important for understanding how the mind controls itself. In the present study, the relationship between chunking (a sequence-level process) and task-set inhibition (a task-level process) in the performance of task sequences was investigated to evaluate the hypothesis that within-chunk facilitation reduces the n-2 repetition cost (slower performance for n-2 task repetitions than for n-2 task switches) attributed to task-set inhibition. An experiment is reported in which subjects were induced to chunk sequences such that n-2 repetitions occurred within or between chunks. Direct evidence of chunking was obtained, and n-2 repetition cost was smaller when n-2 repetitions occurred within chunks than between chunks. These findings are consistent with an elaborated hypothesis that attributes the reduction in n-2 repetition cost to priming of task goals rather than direct modulation of task-set inhibition.