Is there an age deficit in the selection of mental sets?

Efficient selection of actions is dependent on higher-level constraints (mental sets) on lower-level selection. This paper explores the hypothesis that ageing leads to specific impairments associated with higher-level selection between mental sets. Indirect evidence for such a deficit comes from occasional findings of age differences in situations with high executive-control demands (e.g., Mayr & Kliegl, 1993) that are not easily explained in terms of other factors, such as general slowing or working memory parameters. More direct evidence comes from recent results with the so-called task-switching paradigm. Specifically, age-sensitive set-selection processes are indicated by age differences in “global selection costs” (i.e., the response-time difference between task-switching blocks and single-task blocks) which seem to be particularly large when demands in terms of “keeping competing mental sets apart” are high. Finally, data from a new variant of the task-switching paradigm (the “fade-out paradigm”) are reported which show that age differences in global costs persist substantially beyond a phase in which set-selection is actually necessary. Generally, evidence is consistent with the view that in older age, a costly set-selection mode of processing dominates over the more efficient within-set-selection mode of processing, possibly because of a problem with maintaining distinct representations of what ought to be done in the face of competing representations of what could be done in principle.