Pigeons′ Memory for Event Duration in Choice and Successive Matching-to-Sample Tasks

Abstract

Pigeons were trained to discriminate between short (2 s) and long (10 s) house-light samples within successive or choice delayed matching-to-sample tasks, and then were given four types of tests. During one type of test, the delay interval between the sample and test period was manipulated within sessions. Consistent with earlier findings, pigeons in the choice task displayed a reliable choose-short tendency at longer delays, whereas those in the successive task failed to show an analogous respond-short tendency. A second type of test entailed multiple sample presentations: the short and long samples were preceded by short or long pre-samples. Pigeons in both the choice and successive tasks showed a temporal-summation effect rather than a sample-consistency effect. In a third type of test, the intertrial interval was manipulated within sessions. Pigeons in both tasks showed a respond-long bias when the intertrial interval preceding the trial was shortened. In a final test, pigeons received no-sample tests, and tests with a 40-s sample. Pigeons in both groups showed a strong tendency to respond short on no-sample tests, and to respond long following a 40-s sample. It appears that timing processes are similar in the two tasks, but that memorial processes differ.