Independent effects of pictorial displays on perception and action

Although pictorial illusions have been used to study perception for a long time, the effects of such displays on the visual control of actions has rec ently been the matter of some debate. Evidence from a re-analysis of an ear lier study is presented that suggests pictorial displays can exert opposite effects on perceptual size judgements and grip scaling, perhaps because th e two-dimensional elements surrounding the target for a grasp are treated a s potential obstacles. This interpretation was supported by the results of an experiment in which the relative position and distance of two-dimensiona l elements flanking a target had differential effects on perceptual judgeme nts of size and the scaling of grip aperture. (C) 2000 Elsevier Science Ltd . All rights reserved.