Interocular transfer of cardiac conditioning in the pigeon

Pigeons received 30 pairings of a light stimulus (CS) and a brief electric foot shock (US) or random presentations of 30 CSs and 30 USs monocularly. The birds that received the paired presentations showed a clear increase of heart rate during CS presentation periods and maintained the conditioned cardiac response when tested with the naive eye; whereas, those which received the random presentations indicated no increase of heart rate and did not show any systematic change of cardiac response when tested with the naive eye. These results demonstrate interocular transfer of the cardiac conditioning in the pigeon.