On the stability of phencyclidine discrimination in the pigeon.

Pigeons trained to discriminate phencyclidine from saline under a color tracking procedure using second-order schedules were studied over a period of more than 5 years. During this time, many other drugs were studied and a variety of procedural changes were made, yet when phencyclidine discrimination was studied under the same second-order schedule, the phencyclidine generalization curve could be reproduced reliably. When the birds were not tested or given any injections for two months, the typical phencyclidine generalization curve could be generated during the first session that testing resumed. These data illustrate the long term stability of phencyclidine discrimination in the pigeon.