The relationship of luminous intensity and velocity for motion perception and maximum OKN elicitation

The psychophysiological aspects of the luminous intensity stimulus velocity relationship for perceiving a grating pattern and eliciting optokinetic nystagmus (OKN) with maximum slow-phase velocity were studied in two normal human eyes. The results show that (1) both the luminous intensity and target velocity (within the region from 16-56 deg/sec) have a linear relation to the perception of a grating pattern and eliciting of the maximum OKN. (2) The trends of the relation between perception and elicitation are similar, but the slopes of the regression lines are different. (3) No statistically valid directional effect is found on either visual perception or maximum OKN elicitation in humans who have normal binocular vision. (4) For a given stimulus velocity, OKN gain (slow-phase velocity/stimulus velocity) increases to a saturation point as the stimulus intensity increases. The maximum OKN gain decreases as the stimulus velocity increases.