Retention intervals enhance associative competition produced by a preexposed CS

Earlier studies have shown that a latent inhibitor is poor at competing for learning with another conditioned stimulus on a compound conditioning trial. Previous research also has shown that the poor conditioned response produced to a latent inhibitor can be reversed by a retention interval placed after conditioning and prior to testing the conditioned response. In the present conditioned taste aversion experiments, a CS flavor (“A”) was given CS-alone preexposures prior to a pairing of the CS with the US. A serial compound conditioning phase then occurred in which this CS was able to compete with an added novel CS (“B”) when the two CSs were paired with the US. However, prior to the compound conditioning phase, a retention interval occurred lasting either one day or many days (15 days in one experiment and 21 days in another experiment). It was found that the lengthy retention interval enhanced the competitive potential of the pretrained CS. These results show that treatments that enhance the expression of a CS-US association can also enhance the competitive ability of the CS.