Stimulus generalization in monkeys following discrimination training with gray stimuli

Eight rhesus monkeys were trained on a successive discrimination problem with light gray and dark gray stimuli. Following training, generalization tests were given with variable stimuli ranging from white to black. Responses and response latencies were recorded. Responses were faster to the training stimulus values than to middle grays or to the extreme values on the lightness continuum. The theoretical implications of this as compared to other possible findings are developed.