To what extent changes in convergence can contribute to stereoscopic acuity is again considered, using new data. Certain difficulties of obtaining the most desirable measurements of stereoscopic thresholds without and with eye movements are pointed out. Data obtained by the author and by others can be interpreted to show that, physiologically, convergence changes themselves do not contribute to stereoscopic acuity over that due to disparity between the images alone. In the tests where eye movements occur, lower apparent thresholds are found because retinal regions of higher visual acuity and higher stereoacuity come into play.
KENNETH N. OGLE, "Stereoscopic Acuity and the Role of Convergence," J. Opt. Soc. Am. 46, 269-273 (1956)