AGING AND VISUAL-SEARCH - GENERALIZED COGNITIVE SLOWING OR SELECTIVE DEFICIT IN ATTENTION

Selective attention in normal aging was investigated using simple and conjoined feature visual search tasks. The effects of varying the loca tion of the target (central vs. peripheral, left vs. right hemifield) and the complement of distracters, together with variability in task p erformance across subject groups, were also examined. The findings ind icated that the feature extraction stage of visual search was preserve d in older aged subjects. However, there was a differential age-relate d 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 cognit ive slowing. There was no evidence of a speed-accuracy trade-off in th e performance of either search task. The findings of this study contri bute towards the delineation of age-dependent and -independent process es subserving visual selective attention. The performance of older ind ividuals may be relatively well preserved on more automatic, less dema nding tasks such as simple feature search. By contrast, there may be d ifferential age-related impairments on visual search tasks such as con joined feature search, which may require more effortful or controlled attentional processing.