Does increasing absolute conditioned reinforcement rate improve sensitivity to relative conditioned reinforcement rate?

Previous research has demonstrated several procedural modifications that improve the sensitivity of human behavior to relative rates of conditioned reinforcement or S+ production. Denser rates of reinforcement have proved useful in related human operant research, but the influence of denser rates of S+ production has yet to be evaluated. The purpose of the current study was to evaluate how the absolute S+ production rate influenced sensitivity to relative S+ production rate. Thirty undergraduate students were randomly assigned to three groups for which the absolute rate of S+ production varied but the programmed relative rate of S+ production was held constant across groups. Results similar to those of previous research were obtained with many participants; however, the absolute rate of S+ production exerted no systematic effect on sensitivity or the quality of fits of the generalized matching equation. Exploratory analyses suggest that methods ensuring steady-state responding and improving the predictive value of S+ are important directions for future research.