Abstract
The visual system has the ability to generalize a variety of shapes as a common category. At the same time, it is able to distinguish small differences among otherwise similar images. We studied how these two mechanisms interact in the visual system. For this, we introduced some degree of irregularity to highly regular patterns. Our first stimulus was a grid pattern in which the pattern was regular at the center of the stimulus. This regularity was disturbed gradually towards the outer edges of the stimulus. As one looks at the center of such stimulus, the irregular part of the grid slowly becomes regular in percept and eventually the entire stimulus is perceived as a regular grid. The effect seems to reflect the brain's preference for regularity, because reversing the center-peripheral organization (i.e., irregular center and regular periphery) did not result in any perceptual effect. A similar perceptual change was observed for distorted circles. In both cases, the irregular ‘glitches’ disappeared and eventually a coherent regular structure was perceived. Interestingly, the afterimage of an irregular pattern was also regular. The fact that this phenomenon of perceptual regularization requires prolonged viewing suggests some involvement of adaptive neural substrates. That is, information of small-scale deviations from a global picture is represented separately, perhaps in early visual areas, and adaptation diminishes this component selectively. When the signals for the deviations are small, signals for a global picture, or a prototype, may overrule, possibly adjust the low-level representations.