Sensitivity to Changing Environmental Conditions across Individuals with Subtype 2 Automatically Reinforced and Socially Reinforced Self-injury

Applying the evolutionary theory of behavior dynamics to model the subtypes of automatically reinforced self-injurious behavior

The delineation of the subtypes of automatically reinforced self-injurious behavior improved the utility of functional analysis results in predicting treatment efficacy. However, the mechanisms underlying subtype differences remain unclear and difficult to study in clinical populations. Morris and McDowell (2021) attempted to elucidate subtype differences by developing and evaluating models of the subtypes within the evolutionary theory of behavior dynamics. In the current study, we applied techniques from precision medicine to further evaluate the models developed by Morris and McDowell. This evaluation highlighted shortcomings of the existing models and suggested ways they could be improved. Thus, we conducted more extended modeling within the framework of precision medicine to identify models that were more quantitatively similar to available clinical data. Improved models that more closely approximate clinical data were identified. The implications of these models for research, practice, and further applications of the evolutionary theory of behavior dynamics are discussed.

The matching law provides a quantitative description of social time allocation in children with autism

Recent research has developed and evaluated assessments of sociability in which time allocation near or away from an adult who initiates social interactions is used to characterize the participant as social, indifferent, or avoidant of social interaction. Though these qualitative outcomes have been useful, no studies have evaluated methods of obtaining more quantitative measures of sociability. The matching law has been demonstrated to describe a wide range of human behavior and may also be useful in describing social time allocation. We adapted the matching law and assessment of sociability procedures with the aim of providing a more precise, quantitative measure of sociability. We fitted the matching equation to the social time allocation data of 8 children with autism spectrum disorder. The equation was effective in quantifying sociability, accounted for a large proportion of variance in participants' behavior, did so equally well for participants who were social and avoidant, and provided a more sensitive measure relative to those used in previous research. The implications of this methodology, its potential utility, and directions for future research are discussed.

Analysis of unexpected disruptive effects of contingent food reinforcement on automatically maintained self-injury

Research has identified treatment-responsive and treatment-resistant subtypes of automatically maintained self-injurious behavior (ASIB) based on patterns of responding in the functional analysis (FA) reflecting its sensitivity to disruption by alternative reinforcement, and the presence of self-restraint. Rooker et al. (2019) unexpectedly observed reductions in treatment-resistant self-injury while participants performed an operant task. The current study further examined this in nine participants with treatment-resistant ASIB in an example of discovery-based research. An operant task engendering high rates of responding (switch-pressing) to produce food, reduced self-injury across all participants, and eliminated self-injury for some participants under certain schedules. Although this finding must be replicated and evaluated over longer time periods, it provides some evidence that alternative reinforcement can disrupt self-injury in these treatment-resistant subtypes under some conditions. Reinforcer and response competition are discussed as possible mechanisms underlying these disruptive effects, as are the potential implications of these findings regarding treatment.