Chapter 26 Adult Age Differences in Visual Search: the Role of Non-Attentional Processes

Abstract

Contemporary research on adult age differences in visual search has tended to ascribe obtained deficits to age-related declines in either the spatial focusing of processing resources or the ability to divide attention across multiple inputs. This chapter presents an alternate view; namely, that the age deficits in search performance may reflect changes occurring at relatively early stages of processing. In the elderly, preretinal image degradation and slower encoding result in a featurally-compromised representation of spatially-extended search arrays. The older observer must therefore make a decision as to target identity or location without sufficient information. In these circumstances, older observers will base their decisions on feature information distributed across the search array. Their performance will be determined by the consistency between features of the distractors and the correct response for a given search trial. Such a model is consistent with the reduced functional field of view in the elderly, and more specifically with data comparing younger and older observers in their ability to identify and localize non-foveal targets embedded in response-compatible and response-incompatible distractors.