Selective attention in normal aging was investigated using simple and conjoined feature visual search tasks. The effects of varying the location of the target (central vs. peripheral, left vs. right hemifield) and the complement of distractors, together with variability in task performance across subject groups, were also examined. The findings indicated that the feature extraction stage of visual search was preserved in older aged subjects. However, there was a differential age-related impairment in the feature integration stage of visual processing in the two older groups (66-75 years, 76-85 years). This was greater than the magnitude of decline predicted on the basis of generalized cognitive slowing. There was no evidence of a speed-accuracy trade-off in the performance of either search task. The findings of this study contribute towards the delineation of age-dependent and -independent processes subserving visual selective attention. The performance of older individuals may be relatively weel preserved on more automatic, less demanding tasks such as simple feature search. By contrast, there may be differential age-related impairments on visual search tasks such as conjoined feature search, which may require more effortful or controlled attentional processing.
Abstract