Perspective production in a savant autistic draughtsman.

This study examines perspective construction in an autistic patient (E.C.) with quasinormal intelligence who exhibits exceptional ability when performing three-dimensional drawings of inanimate objects. Examination of E.C.'s spontaneous graphic productions showed that although his drawings approximate the 'linear perspective' system, the subject does not use vanishing points in his productions. Nevertheless, a formal computational analysis of E.C.'s accuracy in an experimental task showed that he was able to draw objects rotated in three-dimensional space more accurately than over-trained controls. This accuracy was not modified by suppressing graphic cues that permitted the construction of a vanishing point. E.C. was also able to detect a perspective incongruency between an object and a landscape at a level superior to that of control subjects. Since E.C. does not construct vanishing points in his drawings, it is proposed that his production of a precise realistic perspective is reached without the use of explicit or implicit perspective rules. 'Special abilities' in perspective are examined in relation to existing theoretical models of the cognitive deficit in autism and are compared to other special abilities in autism.