Relearning and subsequent forgetting of semantic category exemplars in a case of semantic dementia.

Over 15 months of longitudinal assessment, a patient with semantic dementia, D.M., improved on tests of naming and category fluency for a specific set of items (Experiment 1). The authors attribute this to his home drill with the names of these concepts plus pictures and descriptions of them. In Experiment 2, D.M. produced significantly more exemplars on category fluency for semantic categories that he had been practicing at home than for nonpracticed categories, an effect that cannot be attributed to an inherent difference between the 2 sets because the fluency performance of control participants revealed no significant difference between the 2 sets. In Experiment 3, D.M. rehearsed some of his previously nonpracticed categories daily for a period of 2 weeks: His fluency scores on the experimental categories improved substantially, but they declined once he ceased the daily drill. The results are discussed with respect to current views of long-term memory, particularly new word learning and forgetting, and to current techniques for facilitating word finding in aphasia.