In 35 sessions of 10 trials apiece, each of eight Ss viewed and judged a display which produced simultaneous brightness contrast. All Ss were given an instructional set toward realistic perception. Members of one subgroup were informed as to the magnitude of their judgments; members of another were not. For every S, there occurred highly significant changes in magnitude of simultaneous brightness contrast over time. There were wide individual differences in the nature of the changes, not all of which were decremental. No significant differences were found as between informed and noninformed groups. The results are viewed as giving limited support to the notion of learning in the perception of simultaneous brightness contrast.