Time discrimination in Columba livia and Homo sapiens.

Pigeons' ability to discriminate stimulus duration, focusing on stimuli less than 1 s in duration, was evaluated in 4 experiments. In Experiment 1, the performances of pigeons and humans were compared with a staircase technique, and in Experiment 2, the method of constant stimuli was used. Both experiments produced similar results: The pigeon and human data were well described by the generalized form of Weber's law (Getty, 1975). Experiment 3 demonstrated that the birds did not use perceived brightness to mediate the discrimination of brief visual durations. Experiment 4 used a modified staircase procedure that yielded a continuous measure of discrimination from absolute threshold (0 s) to about 1 s. The difference thresholds were constant over a considerable range, similar to findings reported by Kristofferson (1980) for human timing.