Minimal age-related deficits in task switching, inhibition, and oculomotor control.

UNLABELLED: BACKGROUND/STUDY CONTEXT: We are often required to carry out complex tasks in changing, context-dependent ways. This task switching requires the rapid realignment of attention to task constraints and may be age sensitive. METHODS: Three experiments, two in which eye movements were recorded, were conducted to assess age-related differences in task switching and inhibitory control. Observers carried out a Same-Different task and Go-No Go task in single and mixed blocks of trials. RESULTS: Other than Experiment 1, although switch costs were observed, they were not larger for older adults compared to younger adults. Furthermore, eye movement and false alarm data demonstrated little evidence of age-related decline in inhibitory and oculomotor control. CONCLUSIONS: A major implication is that, at least when two tasks involve different stimuli and unique responses, older adults are no more likely than younger adults to show task-switching costs or inhibition deficit.

Age differences in the distractor-ratio effect as a function of contrast level.

Latencies (RT) and eye movement measures were used to examine the effects of age and contrast on the distractor-ratio effect (DRE) in visual search. Younger and older adults performed a contrast x orientation conjunction search task where the ratios of white to black distractors and luminance contrast levels were varied. The distractor-ratio manipulation had similar effects for older and younger adults on both RT and the number of fixations required to find the target. Both measures were largely independent of distractor ratio on target-present trials, while both RTs and the fixation number increased with the number of items sharing the target's contrast polarity on target-absent trials. A more detailed analysis of eye movements suggested that younger adults were a bit more adept at attending to the smaller set of distractors, which presumably facilitated both overt and covert search. Generalized slowing can account for the age differences in RT, but the fixation number data speak to another mechanism, perhaps increased cautiousness on the part of the elderly when signal strength is low.