In plain language
Psychological flexibility — the ability to stay open, aware, and engaged in valued action even when experiences are difficult — reliably predicts well-being at the group level. But do its component processes (acceptance, defusion, awareness, self-as-context, values, and committed action, along with their inflexible counterparts) work the same way for everyone? This study used idionomic methods, which start with the individual before generalizing to the group, to find out.
The researchers analyzed ecological momentary assessment data from 167 college students (76% female, average age 23.8) who answered smartphone surveys three times a day for a week — 2,252 measurements in total — rating flexibility and inflexibility subprocesses and their momentary mood. Each person's data were first modeled individually (i-ARIMAX), then pooled with random-effects meta-analysis to quantify heterogeneity, and multilevel vector autoregression was used to compare subgroups that emerged from the data.
As in past research, psychological flexibility and inflexibility each uniquely predicted hedonic well-being on average — but the individual-level variation was enormous. Most strikingly, a small subgroup dubbed Stoics showed a positive link between committed action and sadness: they kept acting on their values, or acted even more, when feeling down. These patterns were invisible in whole-sample analyses, supporting the advantages of an idionomic approach over purely nomothetic group analyses for revealing individual, idiosyncratic patterns that matter for personalizing treatment.
Key findings
- Across 120 individual-level models, psychological flexibility and inflexibility subprocesses uniquely predicted hedonic well-being, with a small average pooled effect (mean absolute pooled effect = .13).
- Heterogeneity was very high: the mean I² statistic was 87.98 (range 75.17–99.46), indicating that group averages concealed substantial, non-random individual differences.
- A subgroup of 10 individuals (about 6%), labeled Stoics, showed a positive within-person relationship between committed action and sadness — the opposite of the typical pattern — replicating across three independent datasets.
- For Stoics, values showed no within-person link to sadness or joy despite strong between-person associations, whereas non-Stoics showed values strongly connected to affect at both levels.
- Among Stoics, stress was positively connected to acceptance within-person, which in turn linked to committed action — a dynamic completely absent from full-sample analyses.
- Loneliness increased sadness for Stoics but also intensified their committed action when sad, an effect only visible through idiographic analysis.
How to cite
APA
Fraser, M. I., Field, K., Ciarrochi, J., Hernández, C., Krafft, J., Klimczak, K., Levin, M. E., Yap, K., Hayes, S. C., & Sahdra, B. K. (2026). Heterogeneity in the links of psychological (in)flexibility subprocesses and well-being: Idionomic insights from an experience sampling study. Journal of Contextual Behavioral Science, 40, 100984. https://doi.org/10.1016/j.jcbs.2026.100984
BibTeX
@article{fraser2026heterogeneity,
title = {Heterogeneity in the links of psychological (in)flexibility subprocesses and well-being: Idionomic insights from an experience sampling study},
author = {Fraser, Madeleine I. and Field, Kathryn and Ciarrochi, Joseph and Hern{\'a}ndez, Crist{\'o}bal and Krafft, Jennifer and Klimczak, Korena and Levin, Michael E. and Yap, Keong and Hayes, Steven C. and Sahdra, Baljinder K.},
journal = {Journal of Contextual Behavioral Science},
year = {2026},
volume = {40},
pages = {100984},
doi = {10.1016/j.jcbs.2026.100984}
}
Related work
- All publications by Joseph Ciarrochi (searchable, with free PDFs)
- Process-Based Therapy & Idionomic Analysis
Author: Joseph Ciarrochi (ORCID 0000-0003-0471-8100). Free copy hosted with permission for scholarly use. Please cite the published version via the DOI above.