EFFECT OF MERIDIONAL DISPARITY ON DEPTH-PERCEPTION

When a meridional-size lens is used to provide magnification in the horizonal meridan for one eye the resulting stereopsis distortion is readily accounted for in terms of the binocular disparity caused by changed angular relations. When the same size lens is used to magnify the vertical meridian for one eye there is an opposite stereoscopic distortion for which is no ready geometric explanation. A perceptually induced mechanism operating in the vertical meridian has been suggested by Ogle. In the present experiment, apparatus was designed to introduce disparity of binocularly fused targets successively in each of several oblique meridians independent of the stereopsis measuring targets. Unlike the above-mentioned results obtained with size lenses, the induced stereoscopic distortion was in the same direction and of essentially the same magnitude for disparity in every meridian. It would follow that the perceptually induced mechanism is not exclusive to the vertical meridian.