Perceived Control and Intrinsic vs. Extrinsic Motivation for Oral Self-Care: A Full Factorial Experimental Test of Theory-Based Persuasive Messages

Abstract

Background: Correlational evidence suggests that perceived control (PC) and intrinsic motivation (IM), key constructs in social cognitive and self-determination theories, may interact to reinforce behavior change. Purpose: This proof-of-principle study examines the independent and synergistic effects of interventions to increase PC and IM upon dental flossing frequency. Methods: University students (n = 185) were randomized in a 2 × 2 full factorial design to receive two computer-based interventions: one to either increase or decrease PC and another to increase either IM or extrinsic motivation. These constructs were measured immediately post-intervention; flossing behavior was measured 1 week later. Results: The interventions to increase PC and PC/IM had main and interaction effects on flossing, respectively. The PC/IM interaction effect was mediated by increases in PC and IM. Conclusions: Combining interventions to increase PC and IM seems to be a promising avenue of research, which has implications for both theory and intervention development.