On the origin of body-related influences on visual perception.

The human body and the potential to move it affect the way we perceive the world. Here we explored a possible origin of such action-specific effects on perception. Participants were asked to enclose a virtual object by movements of their index finger and thumb and judged either the actual finger-thumb distance or the size of the virtual object subsequently. The visual-haptic discrepancy that comes with such virtual grasping resulted in a mutual impact of visual and body-related signals: the visual judgments of object's size were attracted by the felt finger posture and vice versa, judged finger distance was attracted by the size of the grasped object. This pattern was observed in spite of a clear spatial separation between somatic and visual signals and was conceptually replicated using a virtual reaching paradigm. The results indicate that basic mechanisms of multisensory integration accompany the emergence of action-specific effects on perception. (PsycINFO Database Record