ABSTRACT
Similar to most other behavioral disorders included in psychiatric diagnostic manuals, autism is defined clinically by both negative and positive symptoms that uniquely characterize individuals with the disorder. The negative symptoms refer to impairments in specific areas of functioning as compared with typically developing persons. These include problems in the social, communicative, and imaginative domains. Positive symptoms refer to the presence of behaviors that are not evident, at least to the same degree, among typically developing persons. For persons with autism, these include engagement in rituals and the preoccupation with perceptual features. In the study of most groups, both negative and positive symptoms are viewed within the context of generally impaired functioning or problematic behaviors that directly interfere with adaptive functioning. However, among persons with autism, the positive symptoms also include special abilities in certain areas of functioning. For example, a few savant persons with autism show absolute pitch (Mottron, Peretz, Belleville, & Rouleau, 1999c), the ability to reproduce 3-D displays (Mottron & Belleville, 1993), and the ability to recall long lists of words (Mottron, Belleville, Stip, & Morasse, 1998). Similarly, nonsavant persons with autism typically show relative strengths-levels of task performance that are higher than would be expected based on their overall level of development-in detecting simple patterns (Plaisted, O’Riordan, & Baron-Cohen, 1998a, 1998b; O’Riordan, 1998) as well as in completing geometric figures and in reproducing shapes (Mottron, Belleville, & Ménard, 1999b). These examples of enhanced performance are sufficiently common that they need to be included in the conceptualization of frameworks for understanding autism along with both the obviously maladaptive positive and negative symptoms.
