Remembering and knowing: two different expressions of declarative memory.

Amnesic patients and a control group were given a recognition test 10 min after studying words. For each recognized word, participants indicated whether they remembered it (R) or whether simply they knew that the word was presented but had no recollections about it (K). The patients were impaired for both R and K responses, performing like a control group tested after 1 week. Another control group was tested both 10 min and 1 week after study. The proportion of words initially eliciting an R response and later eliciting a K response exceeded the proportion of K responses that shifted to R responses. These data are accounted for if items initially eliciting R responses can also elicit K responses. We conclude that the R-K distinction does not reflect the operation of explicit and implicit memory but reflects instead a distinction within declarative memory. Thus, K responses depend on brain structures damaged in amnesia; R responses depend on these same structures and also on the frontal lobes for contextual information.