Permanent deficit of interocular transfer in binocularly deprived cats.

Fifteen laboratory born cats were used: seven binocularly deprived, four reared under condition of daily alternating monocular exposure and four controls. At the 7th month of age four of the binocularly deprived cats and all the remaining cats were trained monocularly in a two choice apparatus. In the first stage of training the cats learned a test with the right eye and were tested for transfer to the left eye. In the second stage, a new test was learned with the left eye, after which transfer to the right eye was tested. Control and with alternating monocular exposure cats had a normal interocular transfer whereas the binocularly deprived cats showed an impairment. After this training all binocularly deprived cats had the hoods taken off for 8 months and were then trained with new tasks. Their interocular transfer was still impaired. Thus, binocular pattern stimulation in the early period of life - simultaneous or alternate - is necessary for normal interocular transfer.