Prediction of exercise in patients across various stages of bariatric surgery: a comparison of the merits of the theory of reasoned action versus the theory of planned behavior.
Perceived Behavioral Control predicts health follow-through better than liking or social approval.
01Research in Context
What this study did
The team asked bariatric-surgery patients to fill out two short surveys. One survey measured Theory of Reasoned Action items. The other measured Theory of Planned Behavior items.
They wanted to know which theory better predicted who would keep exercising after surgery.
What they found
Perceived Behavioral Control won. When people believed "I can keep walking even when I’m tired," they actually walked more.
Attitude and social-norm scores added almost nothing. The Theory of Planned Behavior survey beat the older Theory of Reasoned Action survey.
How this fits with other research
Mount et al. (2011) looked at parents learning ABA skills. Confidence was the only thing that predicted whether parents used the skills at home. Both studies say the same simple rule: belief in personal control drives real-world action.
Slowiak et al. (2022) asked BCBAs why they stay in the field. Self-care and job-crafting—both forms of Perceived Behavioral Control—cut burnout. Again, control beliefs matter more than attitudes.
Schreck et al. (2016) found many BCBAs still pick non-EBPs because they feel easier. This feels like a contradiction: if control beliefs drive action, why choose weaker treatments? The difference is the target paper measured what people do for themselves; Schreck measured what professionals choose for others. When the choice is personal, control wins. When the choice is professional, ease and social buzz can still win.
Why it matters
Stop asking clients "Do you like this goal?" or "Do others support it?" Ask "Can you do it even when barriers hit?" Add one question: "How sure are you that you can carry out this plan on your worst day?" Use the 1–7 scale. If the answer is below 5, build in extra supports or shrink the task until confidence rises.
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02At a glance
03Original abstract
Obesity is a world-wide health concern approaching epidemic proportions. Successful long-term treatment involves a combination of bariatric surgery, diet, and exercise. Social cognitive models, such as the Theory of Reasoned Action (TRA) and the Theory of Planned Behavior (TPB), are among the most commonly tested theories utilized in the prediction of exercise. As exercise is not a completely volitional behavior, it is hypothesized that the TPB is a superior theoretical model for the prediction of exercise intentions and behavior. This study tested validity of the TPB in a sample of bariatric patients and further validated its improvement over the TRA in predicting exercise adherence at different operative stages. Results generally confirmed research hypotheses. Superiority of the TPB model was validated in this sample of bariatric patients, and Perceived Behavioral Control emerged as the single-best predictor of both exercise intentions and self-reported behavior. Finally, results suggested that both subjective norms and attitudes toward exercise played a larger role in the prediction of intention and behavior than previously reported.
Behavior modification, 2009 · doi:10.1177/0145445509348055