Self-injurious behavior in Rett syndrome: interactions between features of Rett syndrome and operant conditioning.

Operant and biological theories of the cause of self-injurious behavior (SIB) in people with a mental handicap are often viewed as mutually exclusive. In this single case study, interactions between features of Rett syndrome and operant conditioning as determinants of SIB are examined. Functional analysis by analog methodology indicated different functions for two forms of SIB shown by the subject: automatic reinforcement by sensory stimulation and escape from social interactions. It is suggested that features of Rett syndrome established conditions under which operant conditioning of self-injurious responding was maximized. The implications of this interaction between features of syndromes and operant conditioning for the conceptualization of the cause of SIB are discussed and it is proposed that the notion of a unitary cause of SIB is inappropriate. It is more productive to consider operant conditioning as the process that maintains responding against a background of predisposing and mediating factors which may be biologically determined.