08:30 AM - 09:30 AM - Frances McSweeney: Habituation to Reinforcers: Why You Should Care

The rate of operant responding is not constant across experimental sessions even when the programmed rate of reinforcement is held constant. Instead, operant responding often increases and then decreases across the session. Response rates may also decrease without increasing or increase without decreasing. I will argue that response rate changes because the delivery of each reinforcer changes the effectiveness of the following reinforcers through sensitization and habituation. I will discuss the history and potential importance of this finding. I will mention some of the rejected alternative explanations for within-session changes in responding and will defend sensitization- habituation as the major explanation. In particular, I will confirm that four of the generally-accepted, but counterintuitive, properties of habituation also occur for within-session changes in responding. These properties are dishabituation, stimulus specificity, variety effects, and stimulus intensity. Because these properties are counterintuitive, they have important implications for anyone who delivers reinforcers in practice.