Abstract
We determined the empirical horizontal horopter. The criterion is the position in depth of a test patch of random-dot at which a binocular image is fused most quickly. It is assumed that a binocular test object is fused most quickly after exposure when the object is on the horopter, and that the method maps corresponding points in the two retina. In our experiment the subject converged on a fixed point at a given distance and made judgements about a test object at each of several directions on either side of fixation point, i.e. peripheral vision. The test object was a flat patch of random-dot consists of a pair of stimuli presented in a stereoscope. The test object was exposed at each of several depths. Depth of the test object was simulated by varying the horizontal disparity between the dichoptic stimuli relative to the fixated object. After each pair of stereograms was exposed, the subject was required to press a switch to indicate fusion. Fusion was described at a state in which the subject could see a clear and single image without fuzziness. The result confirms that the empirically determined horopter deviates from the theoretical ideal.