Positive Behavioral Contrast Effect and Wheel Running as an Operant Behavior on a Multiple Schedule of Reinforcement

Abstract

Positive contrast was assessed when rats were required to lever press in one component and wheel run in the other component on a mult FR 15 FR 15 schedule of reinforcement. To assess positive contrast in wheel running, lever-pressing behavior was put under extinction and vice versa. Increases in lever-pressing and wheel-running rates under the contrast condition were consistent with previously observed positive contrast effects. Results showed a significantly larger increase with contrast and decrease with extinction for lever pressing effect, relative to wheel running. Similarly, post einforcement pause (PRP) duration increased substantively with extinction and decreased markedly with contrast for lever pressing. In comparison, for wheel running, PRP duration decreased with extinction and did not change with contrast. These differences can be attributed to the automatic reinforcement that wheel-running manifests, but lever pressing does not. These findings were also the first to show a positive contrast effect using wheel running as an operant behavior.