shaping (ABA glossary)

Reinforcing successive approximations of a terminal behavior until the terminal behavior is exhibited.  Differential reinforcement is involved in shaping procedures.  In order to be effective when reinforcing closer approximations, previous versions of the behavior will be put on extinction, i.e.will no longer receive reinforcement.  For example, if you are trying to teach a child to sign, you might first accepting hands clapped together for "more".  As the student becomes more precise with the formation, such as folding their hands you would no longer honor 'sloppier' versions for "more".  Every interaction we have with our environment shapes our behavior.