Abstract: The ability to learn various types of visual or auditory discrimination was studied in macaque monkeys under WGTA or restrained chair.Marked individual difference was found in color discrimination learning in WGTA.One of the outstanding features was that the duration of fluctuation around chance level of correct response varied widely during early stage no matter whether the animals were in WGTA or in restrained chair.The same fluctuation was observed in bright-dark,object or pattern discrimination learning in WGTA.In WGTA,bright-dark,object discriminations were easier than color one,while pattern discrimination was more difficult than the latter.Under restrained condition,even more trials were needed for color discrimination learning than that in WGTA.However,pure tone discrimination in restrained chair was the most difficult task.These results might be useful in selecting proper animal model in psychopharmacological,psychophysiological,and neurophysiological research.