No. 66: Nov-Dec 1989
The first two paragraphs of this study by N. O'Connor and B. Hermelin provide some interesting background concerning the idiot savant phenomenon.
"There are two basic questions which arise from the phenomenon of the idiotsavant. One is whether the specific memory of the idiot-savant is categorically organized or not and the second is whether this memory is IQ independent or IQ related. The first problem needing consideration is therefore concerned with the nature of the memory system which is involved. In the idiot-savant this has, until recently, been deemed to be a relatively unorganized rote memory. It is supposed to be mechanical, inflexible and extremely concrete. However, in a number of studies we have demonstrated that the outstanding memories of idiotsavant calculators and musicians are founded on strategies which are rule based, and which draw on a knowledge of the structure of the calendar or of music.
"In addition to evidence concerning the organized nature of the specific memories of idiot-savants for dates and music, we have also accumulated evidence that the eliciting of rules and the development of rule-based strategies tended to be specific in the particular areas of ability of these subjects. For example, although able to calculate past and future dates rapidly, calendrical calculators were often quite poor in the addition and subtraction of numbers unrelated to the calendar. Similarly, in one experiment, musical memory in an idiot-savant was found to be confined to compositions based on familiar tonal structure, and did not extend to atonal music."
In their study O'Connor and Hermelin showed that the verbal memory factor in mnemonists was independent of IQ; also, data of special interest to the subjects were stored in their memories in categorized form.
(O'Connor, N., and Hermelin, B.; "The Memory Structure of Idiot-Savant Mnemonists," British Journal of Psychology, 80:97, 1989.)
Comment. Psychological studies like the one reported above often do not emphasize the fantastic mental capabilities of idiot-savants. It is apparent that at least some human brains have mental capabilities far beyond and/or radically different from what is needed for survival. What is evolution's purpose here?