Local and global perception examined by reversible suppression of temporal cortex with cold.

We placed cryodes over both sides of the dorsal inferotemporal cortex (TEd) in three monkeys in order to suppress its functions during perception of compound visual images. We used three pairs of images in a concurrent visual discrimination: 1. Congruent pair, a large T made of small Ts and a large 7 made of small 7s with response to the large 7 rewarded. 2. Incongruent pair, a T made of small 7s and a 7 made of small Ts with response to the large 7 rewarded. 3. Random pair, a scattering of small Ts in one stimulus and small 7s in the other with response to the small 7 rewarded. If TEd processes the global but not the local elements of a visual figure, animals with TEd suppressed should see only the local figures and they would fail only on the incongruent stimulus. Alternatively, if TEd processed the local, but not the global elements, they should fail only on the scattered small figures where there was no global element as a cue. Finally, if TEd suppression impairs discrimination of forms, they should be impaired on all the figures because they were the same form, but different size. We found that during TEd suppression, the animals failed on the scattered small elements, but not on the global figures formed of the small elements.