Acquisition of new concepts by two amnesic patients.

Two Korsakoff amnesics (A.G. and G.S.) and two control subjects were taught six new concepts. Each concept was composed of three parts: the name of the concept, the context in which the concept originated and its definition. The learning procedure consisted of two phases: (1) learning the concept names and definitions by means of the vanishing-cues method; (2) practice on examples of the concepts through a classification task: examples were either set in the same context as that given in the original definition or in mixed contexts (same and new contexts). Subjects were then tested after 24 hours, a week and a month on their ability to identify new examples as belonging to one of the conceptual rules studied (transfer tests). Both patients showed substantial learning. Patient A.G. was slow and dependent of the first letter cues in the vanishing-cues learning phase but nevertheless, she acquired a large and flexible conceptual knowledge and this was especially true for concepts that were practised by means of mixed-context examples. Patient G.S. easily learned to associate the definitions with the concept names but her conceptual knowledge remained more limited. These results confirm the existence of a semantic learning ability in amnesic patients. They also suggest that under appropriate learning conditions, amnesics may eventually acquire a new flexible conceptual knowledge.