INTEGRATION OF LOCAL PATTERN ELEMENTS INTO A GLOBAL SHAPE IN HUMAN VISION

The spatial extent of the cortical filters selective for different spa tial frequencies and orientations is limited. We studied psychophysica lly how information from the local filters is integrated into global p attern shapes, i.e., whether performance in the identification of a gl obal pattern consisting of small, locally oriented Gabor elements depe nds on the orientations of those elements, The observer was presented with an E-like stimulus pattern shape comprised of oriented Gabor patc hes on a blank background, and the performance measure was the thresho ld contrast for identifying the orientation of the E pattern (four pos sible rotated orientations), The results showed that contrast threshol ds were significantly lower when the local elements all shared the sam e orientation (e.g., all horizontal) compared with the condition in wh ich the elements had mixed orientations (both horizontal and vertical) . The enhancement effect due to uniform local orientations can be expl ained by two factors: One is local facilitatory interactions between t he orientation selective filters, and the other is second-order inform ation integration across the filters.