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Abstract
The difference in magnification of the images in the two eyes when they turn to view an object in asymmetric convergence should geometrically cause such a rotation of the binocular visual field as to also cause aloss of normal egocentric stereoscopic spatial localization. This loss does not occur. To study the problem of the nature of the compensatory phenomenon, afterimages induced with eyes in symmetrical convergence were localized stereoscopically toith the eyes in asymmetric convergence, or vice versa. The results with four subjects consistently showed a very small rotation of the plane of the stereoscopically perceived afterimages away from the position of geometrical expectation, toward the position more normal to the direction of gaze. The apparent compensation was small. The results suggest that the greater part of the apparent compensation to preserve normal stereoscopic spatial localization with eyes in asymmetric convergence would be a psychological change in the frame of reference associated with the eyes turning to asymmetric convergence. Such a change would be consistent also with the induced effect.