ABSTRACTThe effects of using the criterion of minimum border and brightness equality in making matches between white and monochromatic half-disks have been studied. As long as the subject fixates a point at the center of the bipartite pattern and the effects of blur and overlap or separation are reduced to a minimum the two criteria yield essentially the same results.Differences in matching can be found when bipartite fields of different size are used. These appear to be attributable to macular pigment and the distribution of photoreceptors.