Exemplar-based models assume that object categorization and visual memory for objects rely on the same memory representations (e.g., Hintzman, 1986; Nosofsky 1988, 1991; see also Palmeri & Tarr, 2008). These single system theories contrast with multiple memory-systems theories in which object categorization and memory are assumed to be functionally independent systems mediated by different brain areas (e.g., Squire & Zola, 1996). One source of evidence for independent systems comes from dissociations observed when comparing intact and brain-damaged individuals. For example, amnesics classify as well as normals, but recognize significantly worse (Knowlton & Squire, 1993). A review of the evidence for single memory system models versus multiple memory systems models was reviewed in Palmeri and Flanery (2002).

We showed that the tasks that have been used to assess categorization by amnesics may be flawed in that long-term memory for previously viewed category members seems to be unnecessary to discriminate category members from nonmembers at test. By contrast, without prior exposure to old items in a recognition memory task, accurate discrimination of old and new items is simply impossible. For a number of critical experiments supporting multiple memory systems (Knowlton & Squire, 1994; Reed et al., 1999; Squire & Knowlton, 1995), we showed that a great deal of category structure exists in the sequence of test stimuli, providing information about which items are members of the same category without requiring memory for previously studied category members.

Mack, M.L., & Palmeri, T.J. (in press). Discrimination, recognition, and classification. To appear in M.J. Kahana & A. Wagner (Eds.), Handbook on Human Memory, Oxford University Press.

Nosofsky, R.M., & Palmeri, T.J. (2015). Exemplar-based random walk model. In J.R. Busemeyer, J. Townsend, Z.J. Wang, & A. Eidels (Eds.), Mathematical and Computational Models of Cognition, Oxford University Press.

Palmeri, T.J., & Flanery, M.A. (2002). Memory systems and perceptual categorization. In B.H. Ross (Ed.), The Psychology of Learning and Motivation (Volume 41), Academic Press.

Flanery, M.A., Palmeri, T.J., & Schaper, B.L. (2001). Investigating dissociations between perceptual categorization and explicit memory. Proceedings of the Twenty-Third Annual Meeting of the Cognitive Science Society (peer-reviewed proceedings paper), Boston, MA.

Palmeri, T.J., & Flanery, M.A. (1999). Learning about categories in the absence of training: Profound amnesia and the relationship between perceptual categorization and recognition memory. Psychological Science, 10, 526-530.

Palmeri, T.J., & Flanery, M.A. (1999). Investigating the relationship between perceptual categorization and recognition memory through induced profound amnesia. Proceedings of the Twenty-First Annual Meeting of the Cognitive Science Society (peer-reviewed proceedings paper), Edinburgh, Scotland.