Abstract

The pupil responds to a wide range of physical, physiological and psychological stimuli. Changes in retinal illuminance provide the most immediate and perhaps best understood of the inputs to the pupillomotor system, however many elements of a visual stimulus can trigger a pupillary response. Recent studies using dynamic pupillometry have revealed a response to pattern stimulation which varies systematically with spatial frequency^1-4. Several mechanisms underlying the pattern response have been proposed including changes in local luminance^2,3 and accommodation³. Keenleyside⁵ found no evidence that either of these factors played any significant role in the generation of pupillary responses to sine-wave gratings. In 1985 Barbur and Forsyth⁶ suggested a central origin for the pupil grating response (PGR) and presented data from an individual with an accidentally severed left optic radiation in whom responses to both light and pattern were obtained in the subject's normal hemifield - however, within the blind hemifield, no response to pattern could be elicited despite the presence of a near normal light response.

© 1991 Optical Society of America