Assessing the effects of brief stimuli unrelated to reinforcement

Abstract

Reinforcers are environmental events defined by their effects on behavior. However, brief, arbitrary stimuli can also have reinforcement-like effects, despite being unrelated to food reinforcement. The present thesis explored the potential reinforcement-like effects of brief stimuli across five experiments. In Experiments 1 through 4, pigeon subjects responded for food reinforcement and brief stimulus presentations in a two-component multiple schedule. Neither baseline response rates nor resistance to change during disruption tests were systematically greater in a component with versus without brief stimulus presentations. Additionally, increasing the rate and duration of brief stimulus presentations in Experiment 4 failed to reveal reinforcement-like effects when compared directly with food. In Experiment 5, pigeons chose between independent terminal links in a concurrent-chains procedure. Across conditions, varying the location, duration, and rate of brief stimulus presentations in the terminal links had no systematic effects on preference. In contrast, varying rates of food reinforcers resulted in large and reliable shifts in preference. Therefore, the present thesis did not find any evidence that brief stimuli unrelated to food reliably increase response rates, resistance to change, or preference. These data demonstrate the value of systematic replication, and a behavioral momentum approach to assessing potential reinforcement-like effects.