Age-related differences in switching between cognitive tasks: does internal control ability decline with age?

The present study tested the hypothesis that older adults establish a weaker task set than younger adults and therefore rely more on stimulus-triggered activation of task sets. This hypothesis predicts that older adults should have difficulty with task switches, especially when the stimuli-responses are associated with multiple, competing tasks. Weak task preparation, however, could actually benefit older adults when performing an unexpected task. The authors tested this prediction in Experiment 1 using a repeating AABB task sequence, with univalent and bivalent stimuli intermixed. On some univalent trials, participants received an unexpected task. Contrary to the authors' predictions, expectancy costs were not smaller for older adults. Similar findings were obtained in Experiments 2 and 3, in which the authors used a task-cueing paradigm to more strongly promote deliberate task preparation. The authors found no disproportionate age effects on switch costs but did find age effects on bivalence costs and mixing costs. The authors conclude that older adults do experience extra difficulty dealing with stimuli associated with 2 active tasks but found no evidence that the problem specifically stems from an increased reliance on bottom-up task activation rather than top-down task preparation.