ABSTRACT
Conditioning has usually been described in associative terms. A stimulus is paired with an important event and over time an association is said to form between these two events. Although this pairing of a conditional stimulus (CS) and an unconditional stimulus (US) does not occur in a vacuum but in the presence of other "contextual" stimuli, there has been little effort to place contextual stimuli in a consistent theoretical setting with the CS and the US. A conditioned inhibitor is a CS that takes on motivational properties opposite to those of a conditioned excitor. In the case of conditioned emotional response (CER) conditioning a conditioned inhibitor would inhibit or reduce suppression. Wagner and Rescorla solved this problem by describing a general process by which stimuli become conditioned inhibitors. The only associative manipulation that modified the US preexposure effect in the CER was altering the predictability of the US during exposure, which altered both contextual conditioning and the interference.
