Effects of occasional short interfood intervals on temporal control in pigeons.

This study explored pigeon memory for short time intervals. Occasional (one per session) shorter-than-usual interfood intervals (IFIs) were interspersed in series of longer IFIs. In phase 1, the shorter IFIs were of a magnitude that varied from daily session to session. In phase 2, the shorter IFIs were of one magnitude for 20 consecutive daily sessions. Analysis of the results of both experiments showed that pigeons' memory for an IFI was not restricted to the immediately preceding interval but rather decayed exponentially with a half-life of around three intervals. This effect did not take time to develop and did not change over the course of training. These results have implications for the memory component of both clock and non-clock-based theories of animal timing.