Blocking in Pavlovian Conditioning: Effect of Prior Excitatory Conditioning to a Stimulus Extraneous to Compound Conditioning

Abstract

The effect of prior excitatory conditioning to a stimulus not included in the compound conditioning phase of the typical blocking experiment was assessed in three CER studies. The first experiment, in which rat subjects received A +, C +, or a combination of A + /C + trials prior to AB + conditioning, showed that A + /C + or C + training produced as robust blocking as A + training relative to a control group with no prior conditioning. A second experiment which was designed to assess the role of background cues in mediating the blocking effect indicated that background cues were not responsible for the A + or C + effects, while a third experiment showed these same effects were not mediated by stimulus generalization. The findings of these experiments are interpreted in the context of pseudoconditioning-induced rehearsal of a US representation in short-term memory.