Discrimination of dynamic change and constancy over time by pigeons.

The detection of change over time is critical to the serial integration of reality. Three pigeons, in a same/different go/no-go discrimination, were rewarded for pecking at changing stimuli that oscillated back and forth in brightness over a specific range and not at constant, unchanging stimuli randomly selected from the same range. Experiment 1 tested their capacity to detect increasingly slower rates of change against a constant control. The results indicated that pigeons retrospectively integrate past experience over approximately 20-30 s. Experiment 2 tested combinations of brightness ranges and rates to examine the possible roles of perception and memory in this discrimination. Overall, the results indicate that pigeons can detect continuous changes in brightness over different temporal durations, and several lines of evidence suggest that a combination of perception and memory mechanisms are involved. Implications for the pigeons'experience of the recent past are considered.