Temporal generalization accounts for response resurgence in the peak procedure

The peak interval (PI) procedure is commonly used to evaluate animals’ ability to produce timed intervals. It consists of presenting fixed interval (FI) schedules in which some of the trials are replaced by extended non-reinforced trials. Responding will often resume (resurge) at the end of the non-reinforced trials unless precautions are taken to prevent it. Response resurgence was replicated in rats and pigeons. Variation of the durations of the FI and the non-reinforced probe trials showed it to be dependent on the time when reinforcement is expected. Timing of both the normal time to reinforcement, and the subsequent time to reinforcement during the probe trials followed Weber's law. A quantitative model of resurgence is described, suggesting how animals respond to the signaling properties of reinforcement omission. Model results were simulated using a stochastic binary counter.