Behavior therapy was established by Wolpe and Albert Ellis, who believed that people could be untaught or unlearn through reciprocal inhibition or counterconditioning, as systematic desensitization to overcome various mental illnesses such as anxiety and OCD (McCarthy and Archer, 2013). Behavior therapy uses operant learning principles, such as shaping, that reinforce certain desired ultimate behaviors by starting with a similar behavior (McCarthy & Archer, 2013). Shaping can also be seen as step-by-step work to achieve the desired result. For example, an overweight person who wants to lose weight can start by changing a few unhealthy habits, rather than giving up everything at once, and gradually move towards a stricter diet in order to lose weight. Token economies are another principle of operant learning, whereby tokens, called secondary reinforcers, are used as a form of reward and can be used to purchase or exchange (McCarthy & Archer, 2013). For example, an employee who works hard to get a promotion and gets not only the promotion but also a bonus in the form of a check that can be used to purchase a much-needed massage and an expensive handbag. The only thing behavior therapy couldn't explain was what was happening.