[Pupillary responses evoked by spatial patterns].

Abstract

Human pupillary responses evoked by visual spatial patterns were investigated. Experimental data revealed that: (1) pupillary constriction can be induced not only by increment of luminance but also by change of gratings or checkerboards without change of space-averaged luminance; (2) constriction amplitude increases with increasing difference of spatial frequency; (3) pupillary response can be evoked by changing from uniform brightness to checkerboard patterns or from checkerboard to darkness, without any increment of the local luminance. These results indicate that the human pupillary response system is not merely controlled by luminous flux but also receives and processes visual pattern information.