ND COBRE: INHIBITION AND AGE RELATED CHANGES IN VISUAL SEARCH

North Dakota State University, Fargo ND

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Abstract

The goal of this project is to determine the cognitive mechanisms that contribute to adult age differences in visual search. Visual search, the ability to find designated target objects in a cluttered visual field (e.g., a car in a parking lot), is particularly susceptible to age (Plude, Enns, & Brodeur, 1994). Unless target objects are easily distinguishable from other objects (e.g., based on a distinct physical feature), older adults take longer to identify goal-relevant objects in a visual scene and are more distracted by irrelevant objects. Compromised search ability has important implications for older adults' performance on a variety of everyday tasks including driving, shopping, leisure activities, medication management, and navigating new environments. One particular cognitive process implicated in age-related change in spatial selection is inhibitory control (Kramer et al., 1994; Zacks & Hasher, 1997). One way in which inhibition influences spatial orienting is by slowing the return of visual focus to locations that have already been searched, thus promoting novelty in search (Klein, 2000). If this inhibitory process, called inhibition of return, is compromised, an individual's attention is more likely to return to locations that have already been searched, thus reducing search efficiency. The proposed project will examine the interaction of age and inhibition in the success of visual search using reaction time, eye tracking, and electrophysiological approaches. Moving beyond the traditional paradigms, performance will be examined under conditions that begin to approximate natural search (when multiple items are searched, when an individual has endogenous control over search, and when eye movements are required for search). The basic objective is to shed light on the role of inhibitory processes in visual/saccadic as well as attentional components of visual search. The specific aims are as follows: 1) Examine age differences in the interrelationships of eye movements and attentional shifting during visual search. 2) Characterize age differences in the inhibition of exploratory eye movements during search of detailed scenes. 3) Examine the neural basis of age differences in inhibitory processes of visual search using electrophysiological measures. The goal is to move toward an understanding of the cognitive and neural mechanisms of visual search as it functions in real world contexts. Ultimately, this knowledge will contribute to designing more effective visual environments for older adults and to developing cognitive interventions that enhance detection of critical visual information.