ENHANCED PERCEPTION OF ILLUSORY CONTOURS IN THE LOWER VERSUS UPPER VISUAL HEMIFIELDS

The visual world consciously perceived is very different from the spat ial array of photoreceptor activation present on our retinae; it is co mposed of segregated surfaces, organized into distinct objects. An imp ortant component of this organizational process, the segmentation of a n image into figures and background, is shown to be performed much bet ter in the lower visual field. This finding is demonstrated by the per formance in two tasks that involve the perception of illusory contours . This asymmetry indicates a neural specialization that may be related to the anatomical discontinuity along the representation of the horiz ontal meridian in extrastriate visual cortex.