New psychology research indicates that implicit beliefs about willpower can influence people’s relationships. The study, published in the Journal of Social and Personal Relationships, found that people who believe willpower is a limited resource tend to be less willing to provide support to their romantic partner compared to those who believe willpower is inexhaustible.

The researchers behind the study were interested in examining how people’s willpower theories were related to interpersonal dynamics.

“While working on my PhD, I received a grant to visit Switzerland to work with Dr. Veronika Job for a semester. Both of us had already been studying people’s beliefs about willpower, and nearly all of the research had found that believing that willpower is limited was associated with poorer outcomes (e.g., less goal-pursuit, lower well-being),” said study author Zoe Francis, a PhD Candidate at the University of Toronto.

“I wondered if these same limited-willpower beliefs might have a benefit in interpersonal interactions, since people who get tired easily might be more in-tune with their partner’s fatigue. When we ran the study, though, it didn’t quite turn out that way.”

In the study, 363 individuals living in the eastern United States completed questionnaires that measured their willpower theories, relationship satisfaction, and other factors. The participants, who were all cohabiting with a romantic partner, then completed short online surveys every evening for six days.

The researchers found that participants who held limited-willpower beliefs were more likely to report being fatigued, less happy, and less in control of their life during the evening surveys. These feelings, in turn, were associated with reduced intentions to provide support for their partner.

In other words, those who agreed with statements such as “After a strenuous mental activity, my energy is depleted and I must rest to get it refueled again” were more likely to disagree with statements such as “I am going to do more than my fair share of the household duties” and “I am going to try to ‘be there’ for my partner” during the nightly surveys.

Participants who held limited-willpower beliefs were also more likely to report that their romantic partner was more fatigued and less happy. “Even though limited theorists did notice their partner’s fatigue, that didn’t directly translate to trying to provide more support,” Francis explained.

“A lot of the time, people are trying to balance their own personal needs with the needs of those around them. Your partner might totally get that you are exhausted, but if they feel exhausted themselves, it could be hard for them to properly be there for you. Sometimes all we can do is to be understanding towards each other, and acknowledge that some people feel more tired more readily than others,” Francis told PsyPost.

The researchers controlled for personality traits, self-control, empathy for one’s partner, attachment style, and other factors. But the study — like all research — includes some limitations.

“Our study was correlational, so we do not know whether people’s willpower belief was the reason why they were likely to be more tired, to see their romantic partner as more tired, or to intend to provide less support,” Francis explained.

“Also, because we only collected data from one relationship partner, we don’t know how accurate the participants’ perceptions of their partners were. If we collect data from both partners in the future, we will be able to test their accuracy and also see whether the partners who are receiving support actually feel any more or less supported.”

The study, “You seem tired, but so am I: Willpower theories and intention to provide support in romantic relationships“, was authored by Zoe Francis, Vanda Sieber, and Veronika Job.