Stereopsis and Unequal Luminosities of the Images in the Two Eyes

Abstract

<h3>Introduction</h3> The extent to which a difference in the luminosities of the images in the two eyes can affect binocular vision and, in particular, stereoscopic depth perception has been an intriguing problem to research workers in vision for a long time. The most striking effect, of course, is the Pulfrich stereophenomenon, in which the stimulus object is in motion relative to a fixed background. The bob of a swinging pendulum appears to move in a more or less elliptical path when the image of one eye is darkened by a filter. This phenomenon is usually explained by a decreased reaction time in the physiologic processes of one eye associated with the decreased intensity of its image. The second effect, which may be called "irradiation stereoscopy,"¹was first discovered by Münster²in 1941 and later independently by Cibis and Haber.* In this effect, two separated squares of white cardboard,