Are motor effects of visual illusions caused by different mechanisms than the perceptual illusions?
” Perception 31 ECVP Abstract Supplement Are motor effects of visual illusions caused by different mechanisms than the perceptual illusions? V H Franz, M Fahle, H H Bülthoff In previous studies, we found effects of the Ebbinghaus (or Titchener) illusion on grasping. This contradicts the notion that the motor system uses visual transformations which are (a) different from the perceptual transformations and (b) unaffected by visual illusions [Milner and Goodale, 1995 The Visual Brain in Action (Oxford: Oxford University Press)]. Here, we tested whether the grasp effects are generated independently from the perceptual illusions. This could be the case if the motor system treated the illusion-inducing context elements as obstacles and tried to avoid them. To test this hypothesis, we varied the distance between context elements and target. Aluminum discs (31, 34, or 37 mm in diameter) were surrounded by small or large context circles (10 or 58 mm in diameter) at one of two distances (24 or
