Control Procedures for Classical Conditioning

To ensure that a conditioning procedure is responsible for certain changes in behavior, those changes must be compared to the effects of a control procedure. To conclude that an association between the CS and the US has been established, the investigator must make sure that any change in behavior could not have been produced by prior separate presentations of the CS or the US. Investigators have debated at great length about the proper control procedure for classical conditioning. Ideally, the proper control procedure should involve the same number of presentations as the experimental procedure but with the CSs and USs arranged so that they would not become associated. One possibility involves presenting the conditioned and the unconditioned stimuli in a random order with respect to each other (Rescorla, 1967). This is called a random control procedure. Unfortunately, evidence from a variety of sources indicates that the random control procedure can produce associative learning (Papini & Bitterman, 1990).

A more successful control procedure involves presenting the conditioned and unconditioned stimuli on separate trials. Such a procedure is called the explicitly unpaired control. In the explicitly unpaired control, the CS and the US are presented far enough apart to prevent their association.