 Rewarding stimuli can drive learning in both the form of classical conditioning (Pavlovian conditioning) and operant conditioning (instrumental conditioning).In classical conditioning, a reward can act as an unconditioned stimulus that, when associated with the conditioned stimulus, causes the conditioned stimulus to elicit both musculoskeletal (in the form of simple approach and avoidance behaviors) and vegetative responses.In operant conditioning, a reward may act as a reinforcer in that it increases or supports actions that lead to itself.