THEORY-050: Psychological inflexibility, in which verbal relations give private events aversive functions and make experiential avoidance a general strategy, is a transdiagnostic process in psychopathology

Source

• Hayes, Luoma, Bond, Masuda and Lillis (2006), LIT-555, read in full in NOTE-431 from an early manuscript whose numbers differ from the published article.
• Kashdan and Rottenberg (2010), LIT-553, read in full in NOTE-436.
• Barnes-Holmes, Barnes-Holmes, McHugh and Hayes (2004), LIT-541, read in full in NOTE-430.

Hayes et al. 1996 (LIT-551), which defined experiential avoidance as a functional dimension, the RFT book (LIT-549), and Macri and Rogge’s 2024 meta-analysis (LIT-543) are filed unread. They are named here and carry nothing.

The claim in three parts

1. Mechanism. In humans, stimulus relations are learned in both directions and can be derived without being taught. Once a word or thought stands in such a relation to an event, it can take on that event’s psychological functions (NOTE-430, C1–C3). A report of a shock can become aversive, and a child told that dentists are like doctors can fear a dentist she has never met. So private events (thoughts, feelings, memories) can be as aversive as the events they relate to.
2. Process. Avoiding those private events then becomes a general strategy. ACT calls this experiential avoidance, “the attempt to alter the form, frequency, or situational sensitivity of private events even when doing so causes behavioral harm”. Cognitive fusion, “excessive or improper regulation of behavior by verbal processes”, supports it, and contexts of literality, reason-giving and emotional control foster fusion. Avoidance makes the avoided events more salient, and behaviour narrows (LIT-555, pp. 6–8).
3. Transdiagnostic. The same process appears across disorders. Kashdan and Rottenberg (LIT-553) find rigidity in depression (rumination, emotion context insensitivity, flattened physiological variability) and avoidance of arousal, strong emotion or exposure across panic, generalised anxiety and social anxiety (NOTE-436, C2).

What was actually shown

• Correlation. The ACT manuscript’s meta-analysis finds moderate to strong correlations between its process measure, the AAQ, and distress. The manuscript has 21 studies, with a misprinted point estimate likely meant to be .30. Kashdan and Rottenberg cite the published version as 32 studies with r = .42. Only one two-wave panel addresses direction: the AAQ predicted later distress and job performance, and not the reverse (NOTE-431, C2–C3).
• Components. Small randomised analogue studies (N = 8 to 60) show that acceptance and defusion instructions change discomfort, the believability of negative self-referential thoughts, pain tolerance and avoidance under CO₂ challenge (C4).
• Mediation. Seven studies, mostly self-report, report the targeted processes as mediators of ACT’s effects. The authors note that the mediators were often measured after outcomes had begun to improve (C5). By the standard of THEORY-053, that is the right kind of evidence with the order not established.
• Mechanism. The RFT mechanism rests on laboratory transformation-of- function studies the record has not read. The 2004 paper labels its clinical reading of ACT’s processes “no more than a heuristic” (p. 369).

Kashdan and Rottenberg add two caveats. Whether inflexibility causes psychopathology “is unknown” (NOTE-436, C4). And the global self-report ACT relies on cannot capture a capacity that “unfold[s] over time” across situations (C6). Both are reasons for Proposed.

How it bears on mental causation and on language

• It is an account in which thoughts are not causes by their content. Functional contextualism, ACT’s philosophy, limits causal analysis to manipulable events. “Thoughts and feelings do not cause other actions, except as regulated by context.” Fusion is the name for the contexts in which they do (LIT-555, p. 5). This is a third position beside the record’s mental-causation holdings. Pernu (LIT-147) asks whether intentions cause behaviour as mental or as neural. Kendler (THEORY-048) keeps psychological functions in the explanation. ACT relocates the cause to the person’s history and context, which decide whether a thought’s content governs action at all. What the record does not hold is any comparison of the three.
• It is a claim about meaning as behaviour. RFT treats derived relating as a learned operant (NOTE-430, C2), so the account is also a theory of how symbols acquire the functions of what they stand for. That is why philosophy-of-language is tagged. ADR-021 records that language-as-behaviour has no word of its own yet.
• Literality is what self-model theory calls transparency. ACT’s “contexts of literality” treat a symbol “as one would their referents”: the thought “life is hopeless” is responded to as a hopeless life. Metzinger (LIT-450, NOTE-372) calls a representation transparent when its being a representation is unavailable, so that it is experienced as the thing itself. He writes that “the phenomenology of transparency is the phenomenology of naïve realism”. Fusion is then a thought that functions transparently, and defusion (“I am having the thought that I am no good”) makes it opaque. Neither source cites the other, and the identification is the record’s. It is developed for the self in THEORY-044.

What this does not say

• Not that inflexibility is the only process, or a latent cause. It is compatible with THEORY-058. Avoidance that makes the avoided event more salient is a self-reinforcing loop, and on Borsboom’s terms it would be a constituent of many symptom connections, not a disease behind them. The two conflict only if inflexibility is read as a cause that sustains symptoms whatever their connections. Neither source reads it that way, so no rivals is declared.
• Not that it is the same construct as Salkovskis’s “psychological flexibility”. LIT-538 uses the phrase for meaning-making flexibility and cites none of the ACT literature. Whether the two are one construct is open (NOTE-428, NOTE-437).
• Not that ACT outperforms other treatments. The ACT review does not claim it (NOTE-431, C7).
• Not that emotion is the problem. The account locates the trouble in how private events, emotions included, are related to and avoided, not in having them. Gross’s process model of regulation (LIT-554) intervenes elsewhere, on how an emotion is generated. This account does not take a side on emotion theory.

Note of 2026-10-30: what holds it back

The record holds none of the three results promote_when names. Stockton et al. (LIT-1844, NOTE-1456) find overall flexibility mediating mental-health outcomes in four of five trials against an active treatment, across several disorders. But only three of their twelve studies checked that the mediator changed first, the measures are mostly self-report and not named in the copy read, and it is not the 2024 meta-analysis (LIT-543) that test (1) names, which stays Unavailable. Morrison et al. (LIT-1870, NOTE-1425) weigh slightly against: an acceptance session lowered discounting while the AAQ-II did not change against a waitlist. The sample was 30 non-clinical students, on the global self-report that promote_when sets aside. CLAIM-349 cites this reading as corroboration, not as a ground.