The effect of autonomous and controlled motivation on self‐control performance and the acute cortisol response

Autonomously regulated self‐control typically does not reduce over time as much, compared with self‐control underpinned by controlled motivation. The proposed study tested whether an acute stress response is implicated in this process. Utilizing a framework grounded in self‐determination theory, this study examined whether participants' motivational regulation would influence repeated self‐control performance and acute stress levels, measured by the stress hormone cortisol. A single‐blind randomized experimental design incorporating two motivational conditions (autonomous regulation and controlled regulation) tested these hypotheses. Participants (female = 28; male = 11; M (age) = 22.33) performed three sequential self‐control tasks; a modified Stroop task followed by two “wall sit” postural persistence tasks. Salivary cortisol was measured at baseline and after each of the wall sits. A repeated measures ANCOVA unexpectedly revealed that participants in the controlled regulation condition recorded greater wall sit performance in the first and second wall sits, compared with the autonomous condition. A repeated measures ANCOVA also revealed a significant quadratic interaction for cortisol. Controlled regulation was associated with an increase, and autonomous regulation condition a decrease, in cortisol that subsided at timepoint two. Results imply autonomous motivation facilitates an adaptive stress response. Performance on the self‐control tasks was contrary to expectations, but may reflect short‐term performance benefits of controlled motivation.