Amnesia can facilitate memory performance: evidence from a patient with dissociated retrograde amnesia.

A case is reported of a patient who experienced numerous episodes of transient global amnesia (TGA) during which anterograde amnesia was less prominent than usual, and who developed a permanent selective retrograde amnesia. On formal testing, he performed well on traditional verbal memory tests, but showed marked retrograde amnesia for verbal material, including items on a famous voices recognition test. He was administered a paired-associate learning test where the names of famous personalities for which he was amnesic were associated with incongruous activities (e.g. John Newcombe-singing). Our patient performed better on this task than a group of five matched control subjects. Our observations indicate that in the organization of human memory retrograde amnesia may be fractionated from anterograde amnesia and that in certain situations specific types of amnesia can produce a facilitation effect compared to the performance of control subjects.