Psychophysical evidence for contour integration in striate cortex

Purpose. The spatial interactions between local visual filters that are thought to be the basis of contour integration are known to be strengthened by visual learning (Polat & Sagi, 1994). We took advantage of this fact to study the extent to which contour integration is based on the connectivity of striate cortex. Methods. Three naive observers were trained to discriminate the shape of contours composed of collmear Gabor elements and embedded in a dense background of randomly oriented Gabor elements. Contour shape resembled a rotated C, with the opening pointing either left or right, or else either top or bottom. The observer reported which side of the contour was open (2AFQ. The threshold spatial separation of contour elements increased with training, and transfer of training between different Results. The training transferred neither between different retinal positions nor between different eyes, but did transfer between different globaJ shapes. Conclusions. Contour integration is mediated almost exclusively by the eye-specific connectivity of striate cortex.