Early studies of binocular and stereoscopic vision

The revolution in binocular vision (in the 1830s) was occasioned by Wheatstone's invention and application of the stereoscope to demonstrate depth from retinal disparity. The stereoscope, perhaps more than any other instrument, ushered in the era of experimentation to vision. It fulfilled the scientific desire to examine binocular vision by observation and experiment. The stereoscope is a simple optical device that presents slightly different figures to each eye. If these figures have appropriate horizontal displacements or disparities then depth is seen. Wheatstone achieved for space perception what Newton had for color vision: the phenomena could be removed from their object base. Newton's decomposition of white light into its spectral components removed the perception of color from the colored objects that naturally conveyed it. Wheatstone's decomposition of stereoscopic depth into its disparate projections to each eye removed the perception of depth from the solid objects that naturally conveyed it. Color and depth could be examined in the laboratory, and the methods of the natural sciences could be applied to their investigation.