Grasping the world: object-affordance effect in schizophrenia.

For schizophrenic patients, the world can appear as deprived of practical meaning, which normally emerges from sensory-motor experiences. However, no research has yet studied the integration between perception and action in this population. In this study, we hypothesize that patients, after having controlled the integrity of their visuospatial integration, would nevertheless present deficit in sensory-motor simulation. In this view, we compare patients to control subjects using two stimulus-response compatibility (SRC) tasks. Experiment 1 is performed to ensure that visuo-spatial integration is not impaired (Simon Effect). Experiment 2 replicates a study from Tucker and Ellis (1998) to explore the existence of sensory-motor compatibility between stimulus and response (Object Affordance). In control subjects, the SRC effect appears in both experiments. In schizophrenic patients, it appears only when stimuli and responses share the same spatial localization. This loss of automatic sensory-motor simulation could emerge from a lack of relation between the object and the subject's environment.