Research suggests that, in some cases, mechanical restraints may function as positive reinforcers. In this study, we conducted a functional analysis of severe aggression exhibited by an individual with a history of wearing arm splints. The results of this functional analysis demonstrated that his aggression was maintained by access to the arm splints. Copyright # 2008 John Wiley & Sons, Ltd. Historically, mechanical restraints such as arm splints have been used to prevent severe self-injurious behavior (SIB) as well as to minimize the injury that may result from SIB (Griffin, Williams, Stark, Altmeyer, & Mason, 1984;Sturmey, 1999). In many cases, the use of mechanical restraints can function as punishment or extinction (Mazaleski, Iwata, Rodgers, Vollmer, & Zarcone, 1994), which effectively decreases SIB. However, in some cases, prolonged use of mechanical restraints may lead to the restraint becoming a positive reinforcer. For example, Favell, McGimsey, and Jones (1978) used mechanical restraints as part of a differential reinforcement of other (DRO) treatment for severe SIB with three individuals with mental retardation. They found that providing access to the restraint contingent in the absence of SIB for prespecified periods of time resulted in a reduction in SIB. They subsequently showed that an arbitrary response (placing a marble in a box) could be reinforced by access to mechanical restraints.In light of these findings, it is possible that the loss (or removal) of mechanical restraints may lead to increase in problem behavior. That is, if mechanical restraints are a reinforcer, then the loss of the reinforcer may serve as an establishing operation (i.e., deprivation) resulting in an increase in the reinforcer value of the restraint. This in turn may lead to an increase in the future probability of problem behavior that may be associated with access to mechanical restraints. Therefore, the purpose of this
