Visual memory lateralization in pigeons

Previous experiments employing simple visual discrimination tasks have revealed a cerebral lateralization in the visual system of pigeons with a dominance of the left hemisphere. Until now, visual memory lateralization in birds has not been investigated. To study possible asymmetries of visual memory functions, a simultaneous instrumental discrimination procedure was used. The animals were trained to discriminate 100 different visual patterns from a further 625 similar stimuli. Retention tests were conducted under binocular and monocular conditions. When the subjects looked monocularly, retention performance was significantly higher with the right eye (left hemisphere) than with the left eye (right hemisphere). The results suggest that the lateralization of the pigeon's visual system depends at least partly on an asymmetry in visual memory capacity.