Non-technical Summary
Locus of control and self-control are two personality traits that are both key for understanding people’s behavior. Locus of control describes the belief about the extent to which life events are due to own actions—characterizing people with an internal locus of control—rather than outside forces beyond one’s control—characterizing people with an external locus of control. Self-control is described as the ability to override automatic impulses, and helps people resist temptation and achieve their longer-term goals.
Although locus of control and self-control are distinct concepts, their importance in predicting people’s life success is common to both. In addition, they are also conceptually related. Theoretically, a person’s self-control must depend on the belief that they have some degree of control over what happens to them. Despite this conceptual relationship, large-scale empirical evidence on the link between locus of control and self-control is surprisingly limited within the broader psychology and economics literature.
We provide the first empirical evidence on the direct link between locus of control and self-control, and how they interact in explaining a range of health outcomes. Using data from wave 19 of the Household, Income and Labour Dynamics in Australia (HILDA) Survey, we find that the two traits are indeed distinct constructs. Consistent with theoretical predictions, we also find that a greater internal locus of control is associated with higher self-control. In other words, individuals who believe that life events are mostly due to their own actions tend to also report higher levels of self-control. The association between locus of control and health is reduced once we control for self-control, suggesting that self-control mediates at least part of this relationship. Therefore, part of the explanation for why greater internal locus of control is associated with better health outcomes is because of the relationship of internal locus of control greater self-control. Finally, we demonstrate that having an internal locus of control can amplify the beneficial health impacts of higher self-control, particularly for physical health, physical activity, psychological distress, and health satisfaction.
Our findings have two important implications. First, while conceptually and empirically related, locus of control and self-control are distinct. Thus, analyses using them interchangeably in absence of measures of one or the other should be interpreted with caution. Moreover, our findings clearly indicate the benefits of including both measures in large-scale surveys for a more nuanced understanding of differences in people’s behavior and outcomes. Second, our findings underscore the importance of both internal control beliefs and greater self-control for people’s wellbeing, making both traits excellent targets for intervention: Even though these personality traits are rather stable in adulthood, they have been shown to be malleable especially during childhood and successfully been enhanced by intervention programs in different contexts. Early intervention may thereby yield long-term benefits. Moreover, while self-control appears to be one channel through which locus of control improves health outcomes, the two are also often reinforcing: An internal locus of control can amplify the beneficial health effects of greater self-control. This implies that there could be great efficiency gains by targeting both locus of control and self-control simultaneously.