2008 年 26 巻 2 号 p. 140-148
In this study age-related changes in attentional control were examined by using a visual search task. Eight young adults and eight older adults were asked to detect a target while ignoring any task-irrelevant distractors that could capture their attention (onset distractors). The reaction times (RTs), sensitivity for target detection (d') and the response bias (β) of each participant were measured. The parameter d' indicated the allocation of attention to the target area, and β indicated judgment criteria that were independent of attention. The results revealed that: (1) in the onset distractor condition, the RTs of the older adults were slower than the young adults; (2) the parameter d' was reduced in the older adults as the number of onset distractors decreased; and (3) the response bias did not affect the age-related changes of the RTs even though the parameter (β) was high for young adults and low for older adults. These findings suggested that the deterioration of attentional control of the older adults was related to multiple factors, such as the number of stimuli and the presence of onset distractors.