PERCEPTUAL SPACE OF BRIGHTNESS IN MONKEYS (MACAQUE RHESUS)

Brightness discrimination of black-wite stimuli (1-37 Cd/m; CIE-31 chr omatic coordinates: X = 0.340, Y = 0.304) were studied using choice co nditioning paradigm in two monkeys (Macaque Rhesus). Confusion matrice s were composed of probabilities of instrumental responses to conditio ned and differential stimuli in ten series in which one of the ten int ensities was employed as a conditioned one. Confusion matrices were tr ansformed into the correlation matrices between the vectors correspond ing to the stimuli. Factor analysis of correlation matrices revealed t wo-dimensional circular structure of monkey's brightness perceptual sp ace. This space was principally similar with that in humans, fishes, a nd rabbits. Two eigenvectors which constituted two-dimensional Euclide an space of brightness can be interpreted as bright and dark neuronal channels.