Precision and validity of stereoscopic depth perception from double images.

Abstract

This study reports data on the question as to how precise is stereoscopic depth localization with double images and what is the relationship between that subjective depth and objective depth. Instrumentation was used which permitted a test object to be adjusted relative to a reference object, when both of these were observed in increasing disparity between the images of the two eyes and in increasing peripheral angle. The data show that the precision of the stereoscopic depth seems to decrease exponentially with disparity, becoming very small near the limiting values of disparity for stereopsis. When the test object is adjusted for half the depth of the reference object, and adjusted to be as far in front of the fixation point as the reference is behind, the data show a remarkable validity for a wide range of disparity, until the limiting disparities are approached. Then the stereoscopic depth levels off to a constant value. These results are discussed in relation to the visual processes and spatial localization.