Interocular transfer of pattern discrimination learning in chicks

A previous study found that chicks pecking a key for heat did not show interocular transfer of a pattern discrimination, indicating that the monocularly acquired discrimination was stored as a unilateral engram which was not available to the untrained eye/hemisphere system. In the present study, chicks were trained monocularly on a pattern discrimination and tested for interocular transfer exactly as in the previous experiment, except that a correct pecking response was reinforced by presentation of food. There was good interocular transfer of the discrimination under these conditions. These results are interpreted as indicating that the biological relevance of a learning situation influences the extent of interocular/interhemispheric communication of information. In addition to the findings with respect to transfer, the present study revealed some unexpected laterality effects. Chicks trained first through the right eye (left hemisphere) learned the pattern discrimination faster and showed more savings during the interocular transfer test than chicks trained first through the left eye (right hemisphere). These findings are discussed in terms of possible hemispheric specialization and asymmetry of interhemispheric communication in the avian brain.