In three experiments, human participants pressed the space bar on a computer keyboard to earn points on random-ratio (RR) and random-interval (RI) schedules of reinforcement. Verbalized contingency awareness (CA) for each schedule was measured after the entire task (Experiments 1 and 2), or after each RR-RI trial (Experiment 3). In all three…

Michael (1975) reviewed efforts to classify reinforcing events in terms of whether stimuli are added (positive reinforcement) or removed (negative reinforcement). He concluded that distinctions in these terms are confusing and ambiguous. Of necessity, adding a stimulus requires its previous absence and removing a stimulus its previous presence.…

Reinforcers lose their effectiveness when they are presented repeatedly. Early researchers labeled this loss of effectiveness as "satiation" without conducting an experimental analysis. When such an analysis is conducted, "habituation" provides a more precise and empirically accurate label for the changes in reinforcer effectiveness. This paper…