Knowledge Factors in Everyday Visual Perception

The ability to use aquired knowledge to support performance in complex memory or perception tasks is an important characteristic of human cognition. Although many aspects of memory and perception show decline with advancing age, older adults frequently exhibit preserved or even expert performance in selected everyday domains. The main purpose of this chapter is to offer an explanation of everyday cognition that emphasizes knowledge factors and the component processes that enable (and constrain) the performance of older adults in familiar or everyday visual cognitive tasks. We argue that the availability of task-relevant knowledge facilitates performance by improving the efficiency of information extraction at the level of objects (or percepts). We suggest that the effortlessness of everyday visual perception, regardless of age, is related to the reduced demands of object-level extraction and to the reduced demands of interference associated with familiar processing domains. To support this claim, we refer to recent studies by Clancy and Hoyer (1988, 1990) showing that older experts differ from same-age nonexperts mainly in terms of the efficiency of domain-specific object-level extraction processes; as discussed in this chapter, nonexperts who had little or no special knowledge of the types of items that make up the selected domain showed a pattern of age-related deficits in item-level detection and extraction processes, and experts showed no age-related declines in the processing of relevant information within the selected domain.