VARYING THE STRENGTH OF THE MUNKER-WHITE EFFECT BY STEREOSCOPIC VIEWING

In the Munker-White effect grey target bars appear lighter when they a re flanked by white bars, and darker when they are flanked by black ba rs. It is shown that the effect is enhanced if the patterns are presen ted stereoscopically so that the grey bars appear either behind the gr ating, in which case they are seen as a rectangle that is occluded by the white bars of the grating, or in front of the grating, so that the y form a transparent rectangle. These results are explained in terms o f object perception: contrast enhances differences between an object a nd its surroundings, whereas assimilation reduces differences within a n object.