Frogs presented with two simultaneous andequipotent wormlike stimuli hesitated when the rival objects moved on opposite sides of the midline within the binocular visual field. Competition did not occur between double stimuli when they moved in opposite monocular fields, or both within the lateral view of one eye. Furthermore, the mutual inhibition generated by two nearby prey-objects rotating around the frog disappears after monocular blinding. These data suggest the operation of a crossed-inhibition mechanism between rostral portions of opposite tecta. The ipsilateral visual projections, which traverse the post-optic commissures, appear as likely pathways for this inhibitory process.