The effects of artificial aniseikonic errors on the moving-rod type of depth-perception test were studied in two subjects. Aniseikonia in the horizontal meridian produced a constant error in the setting of the movable rod whose direction and magnitude varied with the direction and magnitude of the aniseikonia. In the Howard-Dolman test the constant errors were only one-third to one-half those predicted from the binocular disparity. In a modified test in which opposing monocular cues were eliminated, the settings showed the expected constant errors of about 65 mm for each one percent difference in the size of the ocular images. The mean variation about the average position of subjective equidistance showed considerable day-to-day variation.
LOUISE L. SLOAN and ADELAIDE ALTMAN, "Aniseikonia and the Howard-Dolman Test," J. Opt. Soc. Am. 43, 473-478 (1953)