STEREOPSIS AND BINOCULARITY IN THE SQUIRREL-MONKEY

The squirrel monkey lacks anatomically demonstrable ocular dominance c olumns, and physiologically it has an ocular dominance distribution in V1 that is very different from that of macaques, with far fewer cells that strongly favor one eye over the other. We tested an alert squirr el monkey for physiological responses to stereoscopic stimuli by measu ring evoked potentials in response to cytclopean patterns generated in dynamic random-dot stereograms. The monkey showed evoked responses bo th to changes in disparity and to shifts between correlation and uncor relation between the two eyes. This result strongly suggests that the squirrel monkey can detect stereoscopic depth, which in turn casts som e doubt on the assumption that ocular dominance columns bear an import ant relation to stereopsis.