Attentional priming in visual search: Age-based differences in feature priming

In visual search demanding focal attention to a feature singleton, trial-to-trial repetition of a target-defining feature or target location substantially reduces RT (Maljkovic & Nakayama, 1994, 1996; Hillstrom, 2000). This attentional priming has been taken to indicate the existence of an implicit short-term memory system to facilitate control of attention and eye movements in naturalistic tasks. Here, an experiment examined the effects of aging on such priming. A group of young adults (mean age = 19 years) and a group of older adults (mean age = 67 years) performed a visual search task requiring attentive discrimination of a feature singleton. Displays comprised three Landolt C's, spaced in equal intervals about an imaginary circle. Two C's were of one contrast polarity, and the third was of the opposite. The observers' task was to indicate the orientation of the contrast singleton. Target polarity and location varied randomly from trial to trial. Consistent with previous reports, repetition of either target-defining feature or target location facilitated search. Magnitude and persistence of location priming, further, were similar in younger and older subjects. However, age-based differences emerged in the magnitude of feature-based priming; the RT benefit of a repeated target feature was roughly twice as large in older as in younger observers. In conjunction with earlier evidence of inhibitory deficiencies in older adults, data suggest that attentional switching between target features, but not locations, may demand inhibition of established attentional set. Representations supporting attentional priming in visual search, though, appear to remain intact with age.