which two concepts can be thought of as opposite processes within the classical conditioning model?

The two concepts that can be thought of as opposite processes within the classical conditioning model are acquisition and extinction. Acquisition refers to the process of learning to associate a neutral stimulus with an unconditioned stimulus so that the neutral stimulus becomes a conditioned stimulus eliciting a conditioned response. Extinction, on the other hand, is the gradual weakening and eventual disappearance of the conditioned response when the conditioned stimulus is repeatedly presented without the unconditioned stimulus. Thus, acquisition builds the conditioned response whereas extinction reduces or eliminates it.