PUPIL RESPONSES TO STIMULUS COLOR, STRUCTURE AND LIGHT-FLUX INCREMENTS IN THE RHESUS-MONKEY

Visual stimuli that isolate pupil color and pupil grating responses in human vision have been used to investigate the properties of stimulus -specific pupil responses in the rhesus monkey. We measured and compar ed pupil responses to light Aux increments, isoluminant chromatic stim uli, and gratings of equal and lower space-averaged luminance. The par ameters investigated were luminance contrast and chromatic saturation. The results demonstrate clearly the existence of pupil color, pupil g rating and pupil light reflex responses in the rhesus monkey. Comparis on of pupil color and pupil grating responses of equivalent amplitude reveals similar onset response latencies. However, both are approximat ely 40 ms longer than the corresponding pupil light reflex latency. In general these pupil responses are qualitatively similar to those obse rved in humans. However, when compared to equivalent human data, pupil onset response latencies are some 80-100 ms shorter and the pupil sho ws more rapid recovery from constriction. (C) 1998 Elsevier Science Lt d. All rights reserved.