A functional analysis of hair pulling.

We experimentally assessed the functions of hair pulling and hair manipulation of a 19-year-old woman (Kris) with moderate mental retardation and cerebral palsy. In Phase 1 a functional analysis revealed that Kris pulled and manipulated hair for the greatest amount of time in the alone condition, suggesting that the behaviors were maintained by some form of automatic reinforcement (Vaughan & Michael, 1982). In Phase 2 we assessed the nature of the sensory stimulation that maintained hair pulling by providing continuous access to previously pulled or cut hair and, thereafter, by having Kris wear a rubber glove. The results suggested that hair pulling was maintained by digital-tactile stimulation (automatic positive reinforcement). These findings are discussed, and recommendations for further analyses of automatically reinforced habit behaviors are provided.