Ongoing, Explicit, and Direct Functional Assessment is a Necessary Component of ACT as Behavior Analysis: A Response to Tarbox et al. (2020)
Treat private events like any other behavior: assess function first, then apply ACT.
01Research in Context
What this study did
Sandoz et al. (2022) wrote a position paper. They argue that ACT must include an explicit functional assessment to count as ABA.
The authors answer Tarbox et al. (2020). Tarbox had said ACT can be behavior analysis without extra FA steps. Sandoz says that view risks harm.
What they found
The paper does not report new data. It states that verbal targets in ACT must be assessed like any other behavior.
Form alone is not enough. You must test the function of thoughts, feelings, or urges before you treat them.
How this fits with other research
Hoffmann et al. (2016) welcomed ACT into ABA with no FA caveat. Sandoz et al. (2022) closes that gap by demanding explicit assessment.
Call et al. (2024) show FCT can work even when the FBA skips the functional analysis. This seems to clash with Sandoz, but Call looked at tangible problem behavior, not private events. Sandoz targets verbal behavior that only the client can feel.
Contreras et al. (2023) found descriptive assessments match FA only half the time. This supports Sandoz: if you want to be sure, run the full FA.
Dixon et al. (2025) push for full ACT/RFT integration. They build on Sandoz by accepting that new rules for FA must come with the package.
Why it matters
Before you bill ACT as ABA, treat each verbal target like a problem behavior. Run an FA or at least a structured descriptive check. Document the maintaining variables, then pick ACT moves that match that function. This keeps your practice inside the ABA tent and protects clients from vague or mismatched treatment.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Pick one client with worry talk. Do a 10-minute analogue FA on it today.
02At a glance
03Original abstract
Tarbox et al. (2020) offered preliminary functional analyses and practical guidelines for incorporating acceptance and commitment therapy (ACT) within the scope of practice of applied behavior analysis (ABA). Although we agree that this is a needed goal, the approach taken by the authors gives rise to important conceptual, ethical, and practical concerns that warrant further discussion. In particular, we propose that explicit functional assessment of behavior (FA) is necessary in any intervention said to be ABA, and we wonder about the apparent omission of explicit FA throughout the article. We question what we read as the authors’ tacit assertion that the functions of verbal stimuli can be inferred based on behavioral topography, that the function of verbal behavior can likewise be inferred based on form, and that behavior–behavior relations are both causal and predictive of behavior, irrespective of context. Furthermore, we consider whether a number of procedures for functional assessment presented in the article under consideration are consistent with established ABA best practices. Finally, we discuss the extent to which ACT interventions absent explicit FA in ABA interventions introduces the possibility that the interventions may do harm, arguing that further discussion around competence and scope of ethical practice for behavior analysts who wish to incorporate ACT into their work is needed.
Behavior Analysis in Practice, 2022 · doi:10.1007/s40617-021-00607-2