The value of a reinforcer may change based on antecedent events, specifically the behavior of others (Bruzek & Thompson, 2007). In the current study, we examined the effects of manipulating the behavior of the therapist on problem behavior while all dimensions of reinforcement were held constant. Both participants' levels of problem behaviors increased as a function of the altered behavior of the therapist without direct manipulation of states of satiation or deprivation. (Contains 1 figure.)