Interocular generalization: a study of mirror-image reversal following monocular discrimination training in the pigeon.

Generalization gradients along a continuum of angular orientation were obtained from four pigeons, following monocular training on a discrimination between a 45 degrees oblique line (S+) and a 135 degrees oblique line (S-). All pigeons were trained on a chain DRO VI 1 schedule of reinforcement. Generalization gradients obtained with the trained and untrained eye were compared. All pigeons responded maximally to the 45 degrees line (S+) when tested with only the trained eye open. During generalization tests of interocular transfer with only the untrained eye open, three pigeons responded maximally to S- (135 degrees ), the mirror-image of the stimulus associated with reinforcement during training (45 degrees ). The other pigeon failed to show interocular transfer of the discrimination. Interocular reversal of left-right mirror-image stimuli has not been reported for any other species.