When the Affordances Disappear: Dynamical and Computational Explanations of Optic Ataxia

Two options fuel the debate on the cognitive processes underlying the perception of affordances. On the one hand, the ecological theory of affordance fits with the methodological assumptions of the dynamical systems theory of cognition. On the other hand, it is nowadays common to conceive the perception of affordances within a computational framework. This article defends the explanatory power of a computational approach and aims to extend the concept of affordance beyond the boundaries of the dynamical systems theory of cognition. For that purpose, I consider the case of patients suffering from optic ataxia, a condition in which some aspects of visual guidance over reaching with the hand are lost following a lesion in the left parietal cortex. Etiological considerations, indeed, reveal that a computational approach to the perception of affordances allows for an explanation of ataxic behavior that is not available to the dynamical systems theory.