Category rule learning was examined in two amnesic
patients using the perceptual categorization task (e.g.,
Ashby & Gott, 1988; Filoteo & Maddox, 1999). Traditional
accuracy-based analyses as well as quantitative model-based
analyses were performed. Unlike accuracy-based analyses,
the model-based approach allowed us to examine both categorization
rule learning and variability in the trial-by-trial application
of the participant's categorization rule. The results
indicated that the amnesic patients were as accurate as
the controls in learning a complex, nonlinear rule over
a large number of trials. The model-based analysis indicated
that, in general, the amnesic patients learned the categorization
rule as well as controls and applied their rule as consistently
as controls. Categorization performance on a second day
of testing revealed that amnesic patients can retain the
categorization rule over a 24-h period. These results suggest
that the brain regions damaged in amnesia are not involved
in category learning or memory for the category structures.
(JINS, 2001, 7, 1–19.)