Tests of two explanations of response elimination by noncontingent reinforcement

Abstract

Two experiments are reported on the elimination of autoshaped keypecking in pigeons by introducing added feedings that have the effect of removing the contingency between keylight (CS) and feedings. In Experiment 1, added feedings were signaled, by an already conditioned stimulus, in one group but not in another. Contrary to the Rescorla-Wagner theory, but consistent with scalar expectancy theory, responding in these groups declined at equal rates. In Experiment 2, following acquisition, some groups were exposed to repeated sessions in which they received feedings alone prior to receiving both CS and feedings noncontingently. Although prior exposure to feedings did reduce the total amount of responding in subsequent noncontingent sessions, it did not, contrary to scalar expectancy theory, reduce the initial level of responding to the CS. It is suggested that a differential between reinforcing conditions in the CS as compared with neighboring non-CS periods is more fundamental to conditioning than is acknowledged in the Rescorla-Wagner theory or in scalar expectancy theory.