Objective: The Health Action Process Approach (HAPA) proposes principles that can be translated into testable hypotheses. This is one of the first studies to have explicitly tested HAPA's first 2 principles, which are (1) health behavior change process can be subdivided into motivation and volition, and (2) volition can be grouped into intentional and action stages. The 3 stage groups are labeled preintenders, intenders, and actors.
Method: The hypotheses of the HAPA model were investigated in a sample of 1,193 individuals with Type 2 diabetes. Study participants completed a questionnaire assessing the HAPA variables. The hypotheses were evaluated by examining mean differences of test variables and by the use of multigroup structural equation modeling (MSEM).
Results: Findings support the HAPA's 2 principles and 3 distinct stages. The 3 HAPA stages were significantly different in several stage-specific variables, and discontinuity patterns were found in terms of nonlinear trends across means. In terms of predicting goals, action planning, and behavior, differences transpired between the 2 motivational stages (preintenders and intenders), and between the 2 volitional stages (intenders and actors).
Conclusions: Results indicate implications for supporting behavior change processes, depending on in which stage a person is at: All individuals should be helped to increase self-efficacy. Preintenders and intenders require interventions targeting outcome expectancies. Actors benefit from an improvement in action planning to maintain and increase their previous behavior. Overall, the first 2 principles of the HAPA were supported and some evidence for the other principles was found. Future research should experimentally test these conclusions.
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