In 2 experiments, the Muller-Lyer illusion (F. C. Muller-Lyer, 1889; N = 16
) and the parallel-lines illusion (W. Wundt, 1898; N = 26) clearly affected
maximum preshape aperture in grasping (both ps < .001). The grasping effec
ts were similar but not perfectly equal to the perceptual effects. Control
experiments show that these differences can be attributed to problems in ma
tching the perceptual task and the grasping task. A model is described stat
ing the assumptions that are needed to compare the grasping effects and the
perceptual effects of visual illusions. Further studies on the relationshi
p between perception and grasping are reviewed. These studies provide no cl
ear evidence for a dissociation between perception and grasping and therefo
re do not support the action versus perception hypothesis (A. D. Milner & M
. A. Goodale, 1995).