RAT TOYS, REINFORCERS, AND RESPONSE STRENGTH - AN EXAMINATION OF THE R-E PARAMETER IN HENNSTEINS EQUATION

The response-strength equation is a mathematical model used to explain responding on variable-interval (VI) schedules. This equation has two fitted parameters, k and R-e. Empirical research suggests that k is a measure of motor performance and R-e is a measure of background sourc es of reinforcement relative to the arranged reinforcer. This experime nt examined the interpretation of the R-e parameter by augmenting the background reinforcement with a qualitatively different source of back ground reinforcement. Rats were food deprived and received sucrose sol ution for lever responding. Each experimental session consisted of a s eries of seven VI schedules, providing reinforcement rates that varied between 20 to 1200 h(-1). Occasionally, cardboard tubes were introduc ed into the experimental chambers in order to provide the rats with an other source of reinforcement distinct from the lever-response specifi c sucrose reinforcer. The k parameter did not change systematically as a result of the experimental manipulations, but R-e was significantly larger when tubes were introduced into the chambers. These results ar e consistent with the interpretation that k and R-e measure two indepe ndent and experimentally distinguishable parameters and that R-e is a measure of reinforcement of background sources to the arranged reinfor cer. (C) 1997 Elsevier Science B.V.