Stimulus control of responding in the early trials of differential conditioning

Abstract

In Experiment 1 two groups of rats were given 12 differential conditioning trials, seven to the rewarded alley (S+) and five to the nonrewarded alley (S−), prior to being extinguished in both alleys. Group S−S+ received S+ trials, following S− trials in acquisition, while Group S+S− did not receive S+ trials following S− trials in acquisition. In extinction S+ and S− trials were presented according to a quasi-random sequence for both groups. Running on the last 3 trials of acquisition was found to be faster following S+ than following S− trials. Group S−S+ showed greater resistance to extinction and less discriminative responding in extinction than Group S+S−. These results suggest that responding in differential conditioning is controlled not merely by S+ and S− but by the memories of reward (S R) and of nonreward (S N) as well. When the joint effects of both classes of cues were considered, e.g., S R+S+, responding in the early trials of differential conditioning was shown to be highly orderly. Experiment 2 was highly similar to Experiment 1 except that Groups S−S+ and S+S− were equated along dimensions not equated in Experiment 1. The results obtained in Experiment 2 were highly similar to those obtained in Experiment 1.