The role of suppression in resolving interference: evidence for an age-related deficit.

Difficulty with memory retrieval is a salient feature of cognitive aging and may be related to a reduction in the ability to suppress items that compete for retrieval. To test this hypothesis directly, we presented a series of words for shallow coding that included pairs of orthographically similar words (e.g., ALLERGY and ANALOGY). After a delay, participants solved word fragments (e.g., A _ L _ _ GY) that resembled both words in a pair but could only be completed by one. We measured the consequence of having successfully resolved competition by having participants read a list of words including the rejected competitors as quickly as possible. Response time was compared with control conditions that did not require resolving competition. Older adults showed no evidence of suppression; instead they showed priming for the competitors, in sharp contrast to strong suppression effects previously observed in younger adults. Whereas previous studies have provided clear evidence for suppression deficits by examining the ability to produce targets in high interference situations, here we provide direct evidence for a suppression deficit by examining the accessibility of rejected competitors.