Sheppard, Mitchell and Ropar investigate whether individuals with autism are less likely than control participants to use object-specific drawing schemata which do not depict the model they actually see. Self-taught savant skills are much more frequent in autistic populations, and it is assumed that these may be responsible for a less conceptual approach which allows lower-level perceptual processing to prevail. However, because the empirical results from previous research did not prove to be conclusive, Sheppard, Mitchell and Ropar in several studies used tasks where in one condition a purely geometrical form was presented, while in the other condition features were added to convey the impression of a more meaningful object from everyday life. In children and adults without autism, meaningfulness could lower or enhance the level of drawing, depending on the kind of object, while spatial complexity appeared always to make drawing more difficult. Individuals with autism, however, were better able either to overcome or to ignore conceptual object knowledge, in particular when recreating a line drawing. It is concluded that this result reflects a special ability for literal understanding in autism.

a great deal of research on drawing has focused on the effects of conceptual knowledge on performance. Generally, the bulk of findings suggest that prior knowledge about the subject matter interferes with accurate depiction. It seems that participants are liable to rely upon this instead of the viewpoint-specific information projected onto the retina. In other words, people sometimes draw what they know rather than what they see.