Cracking the Code

Chapter 9 delves into models of classical conditioning. Two models are discussed, the first of which is the Rescorla-Wagner model (RWM) and the second the comparator hypothesis. It explains that the RWM is a mathematical model of classical conditioning that states that the associative strength of a conditioned stimulus (CS) to an unconditioned stimulus (US) is equal to the maximal value to which the CS can be associated with the US minus the CS’s associative strength at any point during conditioning trials. It also explains that as conditioning trials progress, the difference between the maximal value of the associative of the CS with the US and the associative strength of the CS to the US at any point during conditioning diminishes until the US is no longer surprising with the occurrence of the CS, reducing the amount of prediction error of the US to 0. The chapter also shows how the RWM explains blocking and overshadowing. The second part of the chapter discusses the comparator hypothesis, which, contrary to other theories of classical conditioning, focuses on the retrieval process rather than the acquisition process. The chapter explains how the comparator hypothesis states that the stimuli that acquired the greatest conditioning strength during acquisition will be more likely to be retrieved and hence more likely to elicit a conditioned response (CR) during testing. The chapter concludes by explaining how the comparator hypothesis accounts for blocking.