Perfect interocular transfer of visual pattern discriminations in split-chiasm cats trained with fading.

It has been reported that the interocular transfer of visual pattern discrimination is imperfect in split-chiasm cats. Perhaps the efficiency of callosal transfer is to some extent determined by the training procedure employed. To test that possibility, we trained 3 split-chiasm cats with a Classical Procedure used in interocular transfer studies (CP cats) and 4 split-chiasm cats with Fading (Fading cats). The Fading procedure consisted of the presentation of two stimuli which differed maximally at the beginning of training; through a series of gradual steps their difference was reduced to a minimal value required to control the desired discriminative behavior. Confirming previous studies, CP cats showed a drop in the discriminative performance when the viewing eye was changed from trained to untrained and they needed additional trials to reattain criterion with the untrained eye. Fading cats, however, showed no difference when the viewing eye was changed; criterion was immediately reached with the untrained eye. It is suggested that the perfect interocular transfer shown by the Fading paradigm represents efficient callosal transmission and stabilized, well organized memory traces.