THE ROLE OF ASYMMETRICAL CODING OF DURATION SAMPLES IN PRODUCING THE CHOOSE-SHORT EFFECT IN PIGEONS

Pigeons were trained on two independent matching-to-duration-samples tasks; one involved 2- and 10-s durations and color choice stimuli, and the other involved 4.5- and 22.5-s durations and line choice stimuli. Accuracy was above chance on mixed-choice probes in which either of the short-duration samples was followed by the two short-associated stimuli. Following explicit training on mixed-choice trials involving choice between the two short- and the two long-associated stimuli, a choose-short effect was demonstrated with both sets of duration samples. These findings are inconsistent with the possibility that the choose-short effect reflects processes of asymmetrical-sample coding and default responding. (C) 1994 Academic Press, Inc.