Increased conditioning in rats to a blocked CS after the first compound trial

Abstract

Two experiments examined the effects of increased conditioning to a blocked conditioned stimulus (CS) with increased compound training, using the conditioned suppression procedure. Experiment 1 demonstrated that conditioning to the blocked element increased after the first compound trial but that there was no additional conditioning after 10 compound trials. Conditioning to the blocking CS was also tested and showed no reliable differences among groups given different amounts of compound training. A small increase in conditioning to the pretrained element after the first compound trial suggested that asympotote might not have been reached during pretraining. In Experiment 2 the level of conditioning to the blocking CS was tested extensively. Conditioning to the blocking element did not increase after pretraining when it was conditioned either in a compound or by itself. This provides strong evidence that the pretraining procedures of Experiment 1 did result in asymptotic learning. The results were interpreted as showing that even a completely redundant CS can acquire excitatory strength when it is paired with a significant event such as footshock.