Inter- and intra-individual differences in semantic priming among young and older adults.

The influences of inter- and intra-individual differences on context effects for young and older adults were examined. Results of a semantic priming task revealed two subsets of older adults who were markedly different in terms of response latency, consistency of responding, and magnitude of priming. Examination of individual response distributions indicated that (a) age differences in priming were localized to trials representing subjects' slowest responses and were eliminated for their fastest responses and (b) inconsistently responding older individuals contributed disproportionately to age differences in priming. The results are interpreted in terms of an interactive-compensatory model in which the ability to sustain attention is related to both priming and word recognition. It is concluded that the failure to examine individual differences may be contributing to the discrepant results in the literature.