A test of Rescorla and Wagner's (1972) prediction of nonlinear effects in contingency learning

Abstract

According to most theories, in a simple contingency learning situation, excitatory learning occurs when the probability of the unconditioned stimulus in the presence of the conditioned stimulus (p1) is higher than the probability of the unconditioned stimulus in the absence of the conditioned stimulus (p2). In Rescorla and Wagner's (1972) model, this prediction varies, depending on the parameters used. In the following experiments, we evaluated whether the difference between p1 and p2 that is required to produce excitatory conditioning is the same, independent of the specific value of p1, or whether this difference varies proportionally to p1's value. To do so, an appetitive procedure of Pavlovian conditioning with rats was used. In four experiments, we compared different levels of contingency (low, medium and high) and found that the difference between p1 and p2 that is required to produce excitatory conditioning increases when the value of p1 is higher. The possibility of analyzing contingency learning as a discrimination between p1 and p2 is also discussed. © Psychonomic Society, Inc. 2011.