Temporal control during maintenance and extinction of conditioned keypecking in ring doves

Timing of conditioned keypecking was investigated using a delay autoshaping procedure. In two experiments, the CS-US interval (ISI) was varied and the temporal pattern of responding during unreinforced probe trials extending beyond the reinforced ISI was recorded. Both experiments showed temporal control of keypecking at ISIs of 4, 8, and 16 sec, regardless of whether the probe duration was held constant (Experiment 1) or covaried with the ISI (Experiment 2). Analyses showed that the timing of keypecking was scalar. Increased responding near the end of the probe was due possibly to independent timing of the probe duration. In a third experiment, a group of subjects trained at an ISI of 8 sec were extinguished by presentation of only probe trials. Although the maximal response rate declined progressively, timing of keypecking did not change.