Remembering and knowing in a patient with preserved recognition and impaired recall

Abstract ROB is a patient who has a severe deficit in recalling recently presented verbal material following rupture and repair of an anterior communicating artery aneurysm [Hanley JR, Davies ADM, Downes J, Mayes A. Cognitive Neuropsychology 1994;11:543–78; Hanley JR, Davies ADM. In: Parkin A, editor. Case Studies in the Neuropsychology of Memory. Hillsdale, NJ: Lawrence Erlbaum, 1997. p. 111–26]. Despite this, her performance on tests of recognition memory is comfortably within the normal range. In the present series of experiments, we investigated whether or not ROB's performance on tests of recognition memory might be associated with a disproportionately large number of correct decisions made on the basis of familiarity rather than contextual retrieval [e.g. Mandler G. Psychological Review 1980;87:252–71]. Contrary to this hypothesis, the results showed that ROB made a high proportion of remember decisions relative to know decisions in recognition [cf. Gardiner JM. Memory & Cognition 1988;16:309–13] and produced a high recollection score when conscious recollection and familiarity were placed in opposition to one another [cf. Jacoby LL, Woloshyn V, Kelley C. Journal of Experimental Psychology: General 1989;118:115–25.]. ROB's recognition memory performance therefore appears to be qualitatively as well as quantitatively similar to that found in the normal population. As ROB has suffered damage to both the fornix and the anterior thalamus, the results of the present study are consistent with the claim that damage to the extended hippocampal system has a much more severe effect on recall than on recognition [Aggleton JP, Shaw C. Neuropsychologia 1996;34:51–62; Aggleton JP, Saunders RC. Memory 1997;5:49–71]. The present results provide no support, however, for the additional suggestion [Aggleton JP, Brown MW. Behavioral and Brain Sciences 1999;22:425–56.] that the extended hippocampal system is necessary for recognition memory decisions that are based on contextual retrieval.