'Limited amnesia': fair or foul?

"Limited amnesia': Fair or foul?

In December 1984, a 55-year-old man was found in his kitchen looking dazed and claiming that it was 1945, he was 14 years old and he had just been hit in the head by a baseball bat during a game with friends. The bat incident did actually occur in 1945, but the man insists that the intervening four decades never took place. His parents' deaths, the members of his family and numerous technological advances apparently were all unknown to him at first. When psychologist Michael McCloskey of Johns Hopkins University in Baltimore examined the man last summer, there was no evidence of brain damage.

Is the man feigning this strange type of amnesia, limited to a specific time period, or is he really trapped in 1945 and unable to get back to the future?

So far, it appears that it is very difficult--even for those who study memory--to tell when someone is taking amnesia. Daniel L. Schacter of the University of Toronto presented a small group of college students with a video tape or novel excerpt containing a violent episode. Some were told to recount the episode as best they could to an experimenter, while others were instructed to behave as though they had forgotten the whole incident. Experimenters were in fact memory researchers who did not know which subjects were trying to fool them. In short interviews, these "expert judges' were unable to detect the amnesia simulators, says Schacter.

Despite that discouraging news, a specific pattern of amnesia may characterize many genuine instances of multiple personality, says Eric Eich of the University of British Columbia in Vancouver. There are clinical reports of cases of "asymmetric amnesia,' in which each secondary personality is able to remember both its own actions and those of the primary personality, but not those of the individual's other incarnations. Eich had 18 female college students produce word associations while consciously assuming three personalities; the primary identity was shy and retiring Sue, along with fun-loving, hedonistic Linda and angry Alice. The subjects then attempted to remember their associations while again pretending to be one of the personalities. In 13 cases, the secondary personalities had a poor memory for Sue's associations. Thus, the absence of "asymmetric amnesia' may be a strong indicator of feigned multiple personalities, says Eich, whereas the presence of the phenomenon may signal the real thing.

There are, however, no handy guidelines to distinguish real from simulated amnesiacs, notes McCloskey. His scientific approach to the "14-year-old' baseball bat victim will continue to be hit-and-miss.