Adult Aging and the Speed of Word Recognition Processes

Laver, Gary

Abstract

Cognitive aging research often indicates a sparing of semantic memory processes and a decline of episodic ones as adults age. This proposal describes four studies of adult age-related differences in the rate of automatic spreading activation involved in semantically and episodically primed word recognition. Semantically and episodically primed targets will be presented in word-naming and Stroop color-naming tasks. In all four studies a response signal procedure will be used to avoid potential age-related response strategies commonly found when participants are given standard response instructions. This procedure equates the processing time for responses across age groups permitting more direct, meaningful comparisons of the rate of response processes across age groups than possible with previous methodologies. Because response times are equated across age groups, the primary measure of interest becomes the rate of improved response accuracy with greater processing times as measured by percent correct and the speed-accuracy function parameters of intercept, slope, and asymptote. The crossing of priming type and response task should provide converging evidence of the rate of automatic spreading activation. The greater the rate of spreading activation from priming to target node, whether semantic or episodic priming, the better the expected word-naming performance. Because this spreading activation may interfere with retrieval of target color information, the greater the rate of spreading activation the worse color-naming performance should be. If aging slows the rate of automatic spreading activation, older adults should show reduced performance relative to young adults in the word-naming task (particularly with weaker episodic priming), but older adults should show better performance than young in the color-naming task. While making no predictions about word naming, inhibitory deficit theory predicts a reduced capacity for older adults to inhibit irrelevant word information in a color-naming task, and therefore diminished performance for them relative to young adults.