Resurgence without overall worsening of alternative reinforcement

Three experiments were conducted with pigeons to assess discriminated periods of nonreinforcement as precipitators of resurgence. Each experiment occurred in three phases. In the Training phase, key-pecking was reinforced according to variable-interval schedules that alternated between two response keys (Experiment 1) or were concurrently available on two response keys (Experiments 2a & 2b). In the Alternative-Reinforcement phase, responding to one key was extinguished, while that to the other was reinforced according to tandem schedules. These then were replaced by chained schedules with the same programmed reinforcement rate in the Resurgence-Test phase. Resurgence occurred both when the signaled period of nonreinforcement was a darkened keylight in the terminal link of the chain schedule (Experiment 1) and a darkened keylight (Experiment 2a) or keylight color change (Experiment 2b) in the initial link of the chain schedule. Thus, signaled periods of extinction, without accompanying reductions in reinforcement rate, precipitated resurgence, suggesting that resurgence is not the result of worsening of overall reinforcement conditions, but also occurs when local conditions of reinforcement are worsened.