Final answer:
The success of contingency contracts is primarily due to positive reinforcement, which is a core principle of operant conditioning, a form of learning where behaviors are influenced by their consequences.
Step-by-step explanation:
The success of contingency contracts is most likely due to positive reinforcement that results from the rewards provided. This concept stems from operant conditioning, a theory proposed by psychologist B.F. Skinner, which suggests that the motivation for a behavior occurs after the behavior is demonstrated, with consequences shaping the likelihood of future behaviors. Positive reinforcement, in this context, means adding something desirable to increase the frequency of a behavior, and it is found to be an effective tool in learning and behavior modification.