Role of Involuntary Eye Movements in Stereoscopic Acuity

Involuntary eye movements have been suggested as the basis for the resolution of the small differences in visual angles which have been reliably found in stereoscopic acuity determinations. By the use of the stabilized image technique it is possible to compensate optically for the effects of these movements, so that the image remains on the same set of receptors. An optical apparatus was constructed in which the images presented to both eyes were stabilized. Stereoscopic thresholds were obtained for three subjects under both normal and stabilized viewing conditions for exposure times from 0.02 to 1.00 sec. Thresholds obtained under both conditions decrease with an increase in exposure time with no significant difference in the rate of decrease. This conclusion is consistent with static theoretical concepts but conflicts with a dynamic theory of stereoscopic acuity.