Cognitive processing of drawing abilities

This critical review examines constructional apraxia from a cognitive neuro psychological perspective. To our knowledge, van Sommers (1989) is the only re searcher to present a global cognitive model of drawing abilities. I-Ic organizes it into two hierarchical systems: Marr's model of visual percept ion and a graphic production system. The latter comprises four hierarchical ly organized components: depiction decisions, production strategy, continge nt planning. and articulatory and economic constraints. Van Sommers' model will be discussed in light of other models and on the basis of empirical ne uropsychological studies (Farah, 1984; Kosslyn & Koenig, 1992; Roncato, Sar tori, Masterson, & Rumiati, 1987; van Sommers, 1989). We find that: (1)the Kosslyn and Koenig visual perception model describes more accurately the pe rceptual components underlying copying than the visual perception system of van Sommers' drawing model, (2) Van Sommers' arguments in favor of a depic tion processing as opposed to visual imagery are not convincing, (3) Van So mmers' assumption that a production strategy is a component is unclear, and (4) articulatory and economic constraints are not cognitive components, bu t constraints imposed during action programming. This literature review lea ds to a discussion of future research topics and the specificity of constru ctional apraxia. (C) 1999 Academic Press.