Fig. 1.

Example stimuli for free fusion. Therectangle shows diagrammatically the location of a putative receptive field. In A, corresponding parts of the stimulus overlie the receptive field. In B, the stimulus within the receptive field is identical to A, but noncorresponding parts of the stimulus are within the receptive field. Despite the fact that one of these stimuli is seen in front of the fixation cross and one is seen behind, the stimulus within the putative receptive field is the same. For clarity of exposition, the disparity is applied by translating only the left image in this diagram. During recording, disparity was applied with a symmetrical displacement of both monocular half images.