Interocular transfer of learning in horses ( Equus caballus)

Abstract

Summary Interocular transfer (IOT) of pattern discriminationswas studied in two horses (Equus caballus). An Anglo-Arabian mare and a Paint gelding were monocularly occluded and conditioned to choose the positive stimulus in a simultaneous two-choice discrimination task. When a criterion of ≥18/20 correct responses over two consecutive blocks of 20 trials was reached, the trained eye was covered and the stimuli presented to the untrained eye. Testing was continued until criterion was reached with this eye. Four sets of stimuli were presented in this manner. Additionally, two reversal discrimination problems were tested. Stimuli consisted of two-dimensional black patterns on a white background and were presented in a vertical configuration. The horses demonstrated high levels of interocular transfer on the four problems and on the reversal discriminations. The results provide evidence that, contrary to beliefs held by many people, horses are capable of interhemispheric transfer of visual information.