Sensory preconditioning

Sensory preconditioning is a phenomenon of classical conditioning that demonstrates learning of an association between two stimuli during an initial phase where the two stimuli (S1 and S2) are presented together but never followed by reinforcement. During the first stage of the experiment, presentations of S1 are followed promptly by S2. In the second stage of the experiment, S2 is repeatedly paired with an unconditioned stimulus so that it becomes a conditioned stimulus. Finally, in the third stage of the experiment, S1 is presented by itself. The phenomenon is demonstrated if S1 elicits a conditioned response during stage 3.