Evaluating the relationship between the rate and temporal distribution of self-injurious behavior.

Self-injurious behavior (SIB) presents unique challenges as researchers have identified that some SIB may be resistant to treatment. The unit of analysis in this research is often the frequency of behavior with relatively little attention devoted to the analysis of inter-response time relations. We assessed whether changes in the rate of SIB were also associated with changes in the temporal distribution of this behavior in the presence and absence of systematically manipulated environmental variables. This study included three participants diagnosed with profound intellectual disabilities who engaged in SIB maintained by both negative and automatic reinforcement. For two of the participants, we used a multiple baseline design across participants to assess the effects of noncontingent access to preferred activities on both the rate and temporal distribution of SIB. For the third participant, we used a reversal design to assess the effects of a change in daily schedule (i.e., attending or not attending work) on the rate and temporal distribution of SIB. For all three participants, antecedent manipulations decreased the rate of SIB; however, operant contingency values (a measure of temporal distribution) did not change in a corresponding fashion. These data suggest that although antecedent manipulations may decrease the overall rate of the behavior, once SIB is emitted, additional instances are likely to occur close together in time.