Bias effects in perceptual identification: A neuropsychological investigation of the role of explicit memory

Identification of perceptually degraded words can be enhanced by prior expo sure to those words. One theory propose!, that such perceptual priming is d ue to a hi:is mechanism that induces costs as well as benefits in performan ce. Inherent in this theory is the critical assumption that bias effects ob served in normal cognition reflect thr operation of implicit rather than ex plicit memory processes, In the present study, we tested this assumption by examining the performance of amnesic patients in two paradigms that have e licited bins effects in normal participants. In Experiment 1, amnesic patie nts failed to show a normal bias pattern in a forced-choice perceptual iden tification paradigm, exhibition benefits alone in performance. In Experimen t 2, amnesic patients showed normal costs and benefits in a standard percep tual identification paradigm (without a forced-choice procedure), These res ults suggest that bias effects in normal cognition in the forced-choice per ceptual identification paradigm are the product of explicit memory processe s that are impaired in amnesia, but that bias effects in the standard parad igm are the product of implicit memory processes that are spared in amnesia . (C) 2000 Academic Press.