Massed-trial Overtraining Effects on Extinction and Reversal Performance in Turtles (Geoclemys reevesii)

Two experiments with turtles (Geoclemys reevesii) examined the overtrain ing extinction effect (OEE) and the overtraining reversal effect (ORE), under massed train ing conditions. In Experiment 1, three g roups of turtles received 7, 14, or 21 sessions of training in a runway situation for food reinforcement, followed by 15 se ssions of extinction. Extinction was faster, the greater the number of acquisition sessions. In Experiment 2, the two groups of turtles lear ned a spatial discrim ination for food reinforcement either to a criterion (19 of 20 correct re sponses), or to that criterion plus 100 add itional trials of overtraining. W hen the validity of the positions was reversed, lear ning was faster for the overtrained group than for the group trained to a criterion. This evidence of the OEE and the ORE is the ® r st yet reported for a reptile. The resu lts are discussed in the framework of comparative re search on rewardschedule effects.