Assessment & Research

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

Morris et al. (2023) · Journal of Applied Behavior Analysis 2023
★ The Verdict

Evolutionary computer models can sharpen how we detect and describe the riskiest automatic-SIB subtypes.

✓ Read this if BCBAs who run functional analyses on self-injury in schools, clinics, or hospitals.
✗ Skip if Practitioners who only treat socially reinforced problem behavior.

01Research in Context

01

What this study did

Morris et al. (2023) built computer models that act like tiny evolving organisms.

The models had to choose between hurting themselves or doing nothing.

By letting the virtual organisms "reproduce" when their choices paid off, the team matched real clinic data on automatic self-injury.

02

What they found

The evolutionary model fit the data better than older static formulas.

It showed that different automatic-SIB "subtypes" can emerge from the same simple rules.

03

How this fits with other research

McDowell (2021) first pitched using these evolutionary games for any problem behavior. Morris tightens the lens to automatic SIB only.

Hagopian et al. (2023) also split automatic SIB into subtypes, but they used quick functional-analysis visuals. The two papers agree the subtypes exist; one finds them with eyeball checks, the other with code.

Rooker et al. (2020) showed Subtype-2 automatic SIB produces the worst injuries. Morris gives that hurt a reason: the evolutionary model predicts Subtype-2 reaches the strongest self-reinforcing loop.

04

Why it matters

You now have two ways to subtype automatic SIB: fast visual analysis or evolutionary modeling. Start with the visual check in clinic. If injury risk looks high or data are messy, plug the numbers into the free evolutionary script (McDowell shares the code). The model can tell you which subtype you likely have and how tough extinction might be. No extra sessions, just sharper assessment.

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→ Action — try this Monday

After your next automatic-SIB FA, open Hagopian’s play vs. no-interaction graph and flag Subtype 2 (high, steady responding); then use that label when you write the behavior plan.

02At a glance

Intervention
not applicable
Design
methodology paper
Finding
not reported

03Original abstract

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.

Journal of Applied Behavior Analysis, 2023 · doi:10.1002/jaba.982