Responses of a typical CIP neuron showing consistent selectivity to a 3D surface orientation regardless of the context of presentation (sample, match, or nonmatch). The bar beneath each histogram indicates when the stimulus was on. Two markers in each raster line indicate stimulus onset and offset. Responses to three different orientations (135 and 315° tilt plus frontoparallel orientation) are displayed, although unit activity was recorded with a set of nine different orientations. Insets indicate the stimuli presented; solid lines represent the orthographic projection of the simulated plate onto the frontoparallel plane; dashed lines schematically represent the orientation of the surface in depth caused by binocular disparity; and the arrow represents the surface normal.