Testing a bi-factor model to disentangle general and specific factors of motivation in self-determination theory

•Bi-factor analysis is useful for examining specific and general factors of motivation.•Identified and intrinsic regulation were related to physical activity at Time 1.•General motivation predicted physical activity at Time 1.•General motivation predicted Time 2 outcomes above quality of motivation.•Examining specific and general factors of motivation has important implications.

We examined the utility of the bi-factor model for disentangling general motivation and specific motivations (i.e., amotivation, external, introjected, identified, and intrinsic regulations) in relation to goal progress and physical activity (PA). Participants (N = 186 undergraduate students; Mage = 19.26 years) completed assessments of motivation and PA at Time 1. Four weeks later, PA and goal progress were assessed at Time 2. Results indicated that the exploratory bi-factor model specifying motivational regulations as the specific factors and general motivation as the general factor was a good fit to the data. Results of the structural equation model indicated that identified and intrinsic regulations and general motivation predicted concurrent PA at Time 1. A novel finding was that controlling for concurrent PA at Time 1, general motivation emerged as the only predictor of Time 2 goal progress and PA. Results highlight the importance of examining general motivation in addition to quality of motivation in tandem because general motivation emerged as the sole significant longitudinal predictor of PA outcomes.