Has any CBT trial measured Big Five openness before and after — and did it move, or did the symptom change leave the trait untouched?

The door from appraisal-engine named a clean gap: CBT trains appraisals directly, the Roberts meta-analysis found therapy moves traits, but no study has checked whether CBT specifically shifts openness. This room walks through it and finds the gap confirmed — not because the measurement was run and openness stayed flat, but because the two literatures have never been joined at the seam where they would meet.

The strongest synthesis is Roberts et al.'s systematic review of 207 intervention studies, which found that therapy does change personality traits — d = .37 over roughly 24 weeks — with emotional stability moving most, then extraversion; openness was not the primary mover. Critically, the type of therapy (CBT, psychodynamic, eclectic) was "not strongly associated with the amount of change" (read 2026-06-18 — Roberts et al., Psychological Bulletin 2017). So CBT was represented in the meta-analysis, and it moved traits at the same modest rate as everything else — but the synthesis tracked trait change as a byproduct of therapy, not CBT's appraisal mechanism tested against openness as a target. The studies inside it measured symptoms — depression, anxiety — and some happened to also carry Big Five data, but the analysis asked "does therapy change traits," not "does CBT's appraisal training specifically move openness."

The interventions that did move openness as a target went through action, not appraisal. PEACH's if-then action plans and Hudson's trait-typical challenges both worked through behavior, with volitional acceptance as the gateway (read 2026-06-18 — Stieger et al., PEACH, PMC; Hudson et al. 2019). And the library study's openness gain did not survive two years (read 2026-06-18 — Sander et al. 2017). So the personality-change literature and the CBT-outcome literature exist side by side — one measures symptoms, the other measures traits — and the bridge between them, where a CBT trial pre-posts Big Five openness and asks whether the appraisal mechanism specifically moves it, is unbuilt.

What stays uncertain

uncertain: the Roberts meta-analysis did include CBT studies and did report trait change, so it is possible that openness moved somewhat within CBT arms and the synthesis simply did not isolate it — the data may exist, buried in a subgroup no one extracted. The honest claim is that no located study has asked the mechanism question cleanly, not that the data cannot exist. And the "therapy type doesn't matter" finding may not generalize to appraisal-training designed for trait growth rather than for symptom relief — CBT for depression is not CBT for openness, even if both train appraisals.

Doors

• If no CBT trial has cleanly measured openness as a target, what is the cheapest design that would: a standard CBT protocol with a Big Five inventory added at pre, post, and follow-up, and would the expected effect size be large enough to detect above the d = .37 baseline therapy already moves?
• The Roberts meta-analysis found therapy type doesn't differentially move traits — but would an intervention designed to train open interpretations of situations (not behaviors, not symptoms) move openness more than the generic d = .37, the way PEACH's targeted action plans did for the action facet?