Intelligence and savant syndrome: Is the whole more than the sum of the fragments?

An adequate theory of intelligence must provide an account for individual variation in specific cognitive abilities but also for the common variance between these that results in a general factor. However, it must also be capable for providing an account of savant syndrome: rare individuals who display high levels of skill beyond the accomplishments of most people, yet who have low IQs. On the basis of recent research, two characteristics of savant performance are identified; the first is soundly functioning long-term memory that is narrowly focused and the second is a specific aptitude; that is, memory and cognitive processes dedicated to a specific ability. It is concluded that savant skills are not intelligent and that Gardner's (1983) theory of multiple intelligences fails by overstating the relevance of savant skills and because it disregards clear psychometric evidence for a general factor. Vernon's (1971) hierarchical model fails because it cannot accommodate high levels of cognitive skill, independent from general intelligence. Evaluation of the Horn-Cattell model (Horn, 1987), Anderson's (1992) process theory, and Detterman's (1982, 1986) system theory finds that each can accommdate some aspects of savant syndrome but cannot provide a full account. An integration of the Anderson and Detterman models is suggested, which overcomes the reliance of the former on a unitary construct to explain a general factor and extends the latter to include specific aptitudes.