EFFECTS OF QUALITATIVELY DIFFERENT REINFORCERS ON THE PARAMETERS OF THE RESPONSE-STRENGTH EQUATION

This experiment examined the relationship between two qualitatively di fferent reinforcers and the parameters of a quantitative model of rein forced responding, referred to as the response-strength equation or th e Herrnstein equation. A group of rats was first food deprived and lat er water deprived. An 11.5% sucrose solution served as the reinforcer in the food-deprivation condition, and water was the reinforcer in the water-deprivation condition. Each experimental session consisted of a series of seven variable-interval schedules, providing reinforcement rates that varied between 20 and 1,200 reinforcers per hour. The respo nse rates increased in a negatively accelerating function in a manner consistent with the response-strength equation. This equation has two fitted parameters, R and R,. According to one theory, the k parameter is a measure of motor performance, and R, is indicative of the relativ e reinforcement efficacy of the background uncontrollable sources of r einforcement in relation to the experimentally arranged reinforcer. In this study, k did not change as a result of the different reinforcers , but R, was significantly larger in the sucrose-reinforcement conditi on. These results are consistent with the interpretation that it and R , measure two independent and experimentally distinguishable parameter s and provide further evidence that absolute response rate is a functi on of relative reinforcement rate, as implied by the derivation of the response-strength equation based on the matching law.