身体制御と錯視 : 手は騙されないか (特集 : 「心の科学」)

Abstract

This paper discusses how visual illusions have been studied to gain insight into human vision for perception and action. Visual illusions have long been studied by psychologists, contributing to our understanding of visual perception and the underlying mechanisms. In the last decade, physiological and neuropsychological evidence has indicated that we have two distinct visual pathways in our brain for conscious perception and direct action. Again, visual illusion has been playing an important role in psychological studies after the controversial report that visual illusion does not affect action such as manual grasping. But the idea that the hand is not deceived by perceptual illusion is an oversimplification, because there are cases in which real-time manual reaching yielded larger illusion than perceptual judgement did. The frame of reference seems to be the crucial factor, which is innately selected in accordance with the goals of perception and action. Visual illusions therefore differently affect perception and action depending on information processing required, such as relative coding of objects in a three dimensional space or real-time prediction of the target trajectory for action toward it. The findings on visual illusion, when put together, support the idea of distinct visual processing for perception and action in the two brain pathways. This conclusion is further discussed in light of recent ideas and findings in anatomy, physiology, and neuropsychology.