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

Identification of perceptually degraded words can be enhanced by prior exposure to those words. One theory propose!, that such perceptual priming is due to a hi:is mechanism that induces costs as well as benefits in performance. Inherent in this theory is the critical assumption that bias effects observed in normal cognition reflect thr operation of implicit rather than explicit memory processes, In the present study, we tested this assumption by examining the performance of amnesic patients in two paradigms that have elicited bins effects in normal participants. In Experiment 1, amnesic patients failed to show a normal bias pattern in a forced-choice perceptual identification paradigm, exhibition benefits alone in performance. In Experiment 2, amnesic patients showed normal costs and benefits in a standard perceptual identification paradigm (without a forced-choice procedure), These results suggest that bias effects in normal cognition in the forced-choice perceptual identification paradigm are the product of explicit memory processes that are impaired in amnesia, but that bias effects in the standard paradigm are the product of implicit memory processes that are spared in amnesia. (C) 2000 Academic Press.