Learning about categories in the absence of training: Profound amnesia andthe relationship between perceptual categorization and recognition memory

Previous evidence suggests that amnesics can categorize stimuli as well as normal individuals but are significantly worse at recognizing those stimuli . In an extreme case, a profoundly amnesic individual, E.P., was found to h ave near-normal categorization, yet, unlike most amnesics, was unable to re cognize better than chance. This evidence has been used to argue against th e possibility that a common emory system underlies these cognitive processe s. However, we provide evidence that the experimental procedures typically used to test amnesic individuals may be flawed in that initial exposure to category members may be unnecessary to observe accurate categorization of t est stimuli. We experimentally "induced" profound amnesia in normal individ uals by telling them they had viewed subliminally presented stimuli, which were never actually presented. Using the same experimental paradigm used to test amnesics, we observed that participants' recognition performance was completely at chance, as should be expected, yet categorization performance was quite good.