Abstract

With the invention of the stereoscope, loci of retinal stimulation became the focus of investigation for understanding single and double vision. From the first stereoscope experiment Wheatstone (1838) concluded that (a) slightly different pictures can lead to single vision, and (b) “similar pictures falling on corresponding points of the two retinas may appear double and in different places.” Wheatstone’s first claim was immediately accepted. The mechanism responsible for single vision, however, remained unclear; there has been disagreement as to whether suppression or fusion is involved. Our first set of experiments showed that single vision is achieved by suppression in some conditions and by fusion in others. Wheatstone’s second claim, on the other hand, was challenged. Our second set of experiments with a stereogram in which markers were embedded in the crossed or uncrossed areas of the two halffields supports Wheatstone's second claim. The results from our two sets of experiments can be understood in terms of loci of retinal stimulation interacting with other variables, such as extent of disparity and compatibility with other information, rather than being the sole determinant of visual direction.

© 1986 Optical Society of America