Beschreibung:
<jats:p>Recent developments reveal that animals can rapidly learn about intervals of time. We studied the nature of this fast‐acting process in two experiments. In Experiment 1 pigeons were exposed to a modified fixed‐time schedule, in which the time between food rewards (interfood interval) changed at an unpredictable point in each session, either decreasing from 15 to 5 s (step‐down) or increasing from 15 to 45 s (step‐up). The birds were able to track under both conditions by producing postreinforcement wait times proportional to the preceding interfood‐interval duration. However, the time course of responding differed: Tracking was apparently more gradual in the step‐up condition. Experiment 2 studied the effect of having both kinds of transitions within the same session by exposing pigeons to a repeating (cyclic) sequence of the interfood‐interval values used in Experiment 1. Pigeons detected changes in the input sequence of interfood intervals, but only for a few sessions—discrimination worsened with further training. The dynamic effects we observed do not support a linear waiting process of time discrimination, but instead point to a timing mechanism based on the frequency and recency of prior interfood intervals and not the preceding interfood interval alone.</jats:p>