To evaluate the widely held view that slope of generalization gradient and resolution capacity are inversely related, four rhesus macaques were trained to emit a simple operant to a monochromatic hue in the 450-630 m[mu] range. Generalization was then measured under extinction across this range. This gradient was, in all cases, almost horizontal. Operants discriminated with respect to wave length (Sd - S[LAMBDA] about 60 mu apart) were then developed in these Ss and 2 additional Ss. Generalization was measured as before but in nominal 10-m[mu] steps. Each S was trained to discriminate and generalize three successive pairs of stimuli. Some of the gradients revealed differences in slope which were in accordance with the predicted inverse relationship. Analysis of the deviations in gradient slope suggested a relation not to deviations from the average jnd size but to deviations from average cumulated jnd''s. A measure of deviations from such jnd''s was derived and a high negative correlation to the gradient deviations was shown to exist. It was concluded that some infrahuman generalization gradients do reflect the Sd-SG distance in cumulated jnd''s. Some factors that may have masked this relationship in previous research were discussed.