Directional dependence of intraocular transfer of stimulus detection in pigeons (Columba livia).

The eyes of the pigeon (Columba livia) are positioned laterally in the head. Thus, there is only a small area of binocular overlap, which constitutes the frontal visual field and a large area of monocular vision in the lateral visual fields. The conditions were examined under which intraocular transfer occurs in pigeons; that is, the transfer of information between both portions of the visual field of one eye. Different groups of head-fixed birds learned to discriminate the presence of a bright light from its absence in an instrumental conditioning situation with water as reinforcer. After the animals had acquired the task when the stimuli were viewed in either the frontal or lateral visual field, the stimuli were moved into the converse visual field. Transfer was shown to be directionally selective: It occurred when stimulus presentation was changed from the lateral to the frontal visual field but not when this change was in the opposite direction.