The Site of Size Constancy

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Abstract
Under appropriate conditions, with good depth cues, the perception of the bar width or spatial frequency of a pattern of black and white stripes (a grating) shows excellent size constancy. Two gratings at different distances look similar in spatial frequency when the actual width, not the angular width, of their stripes is the same. Adaptation to a high-contrast grating causes a rise in the threshold contrast for detecting gratings of similar orientation and spatial frequency. This aftereffect transfers from one eye to the other, so it probably depends on binocular orientation-selective neurones in the visual cortex. With the adapting grating at three times the distance of the test grating the maximum elevation of threshold occurs for exactly the same angular spatial frequency as that of the adapting pattern. Therefore the neural mechanism for size-constancy scaling probably occurs after the visual cortex, perhaps in the inferotemporal cortex.