Evidence for disparity detecting neurones in the human visual system

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Abstract
1. It is known that adaptation to a grating pattern causes a rise in the contrast threshold for test gratings of similar spatial frequency and orientation.2. We find this after‐effect also to be disparity‐specific. Adaptation to a grating at zero horizontal disparity (at the same distance as the fixation point) causes a greater elevation of threshold for patterns at the same disparity than for those at nearby disparities, closer or more distant than the fixation point.3. Adaptation to a grating at some disparity other than zero causes a disparity‐specific elevation of threshold centred on the adapting disparity.4. This finding also applies if the observer adapts to a grating but single bright bars are used as the test stimuli.5. The disparity‐specific ‘tuning curves’ revealed by these techniques are quite broad, having a half‐width at half‐amplitude of several min of disparity.6. Adaptation to a grating at one disparity causes an apparent change in the distance of test gratings at nearby disparities.7. We compare these psychophysical experiments with the properties of disparity‐selective binocular neurones in the visual cortex of cats and monkeys.