Acquisition and Transfer of Zero-Delay Matching

Six birds were trained to match-to-sample with red, green, and blue stimuli on a zero-delay procedure in which the sample stimulus is presented and then removed at the same time the choice stimuli are presented. The acquisition functions for zero-celay matching show it to be a more difficult task for pigeons than simultaneous matching where the choice response can be made with the sample present. After 42 sessions with red, green, and blue stimuli, yellow stimuli were substituted wherever the blue stimuli had appeared to test the transfer of the matching performance. The results from the transfer tests are considered in terms of a “coding hypothesis.”