Broken-line graphs showing average response to stimuli of nine different orientations in different contexts: sample (closed circles), match (open triangles), and nonmatch (open inverted triangles). A, Responses of a typical neuron showing no contextual modulation of visual response, whose responses to three representative orientations are shown in the rasters and histograms in Figure 3. B, Responses of a typical neuron showing larger responses to match stimuli than to nonmatch stimuli. C, Responses of a typical neuron showing larger responses to test (match and nonmatch) stimuli than to sample stimuli. Dotted lines indicate the spontaneous activity, and error bars indicate SE. FP, Frontoparallel orientation.