In order to study a possible intermittent reinforcement effect in simple discrimination learning, resistance to extinction was compared following discrimination training, regular reinforcement, and intermittent reinforcement using 12 pigeons, 4 in each group. The results support the view that an intermittent reinforcement effect is present in discrimination learning. Further analysis of latency data are presented for the three training conditions. From Psyc Abstracts 36:01:1EJ11J. (PsycINFO Database Record (c) 2006 APA, all rights reserved)