Prenatal exposure to sex hormones predicts gratitude intervention use. Examination of digit ratio, motivational beliefs, and online activities

• We examined how sex and second-to-fourth digit ratio predicted gratitude-related beliefs and behaviors.
• In two studies, women and men with more male-type fingers were more motivated and likely to complete a gratitude intervention.
• Motivation towards gratitude interventions is facilitated by female sex and masculinity.

Men are less grateful than women and less likely to intentionally enhance gratitude via interventions. Yet, little is known if sex differences in gratitude result from biological influences such as prenatal testosterone and estrogen levels – hormones that control the development of sex-specific characteristics. In two studies, we examined how sex and second-to-fourth digit ratio (2D:4D) – an indicator of prenatal sex hormones exposure – predicts gratitude intervention use. In the first study, we tested whether lower 2D:4D (i.e., higher masculinization) would suppress gratitude intervention use. Contrary to expectations, after controlling for sex, women and men with more male-type fingers were more motivated and likely to complete the intervention. In the second study, we replicated these findings using a larger sample and different 2D:4D metric. Our research suggests that motivation towards gratitude interventions is facilitated by female sex and masculinity. These findings provide initial evidence for the biological grounding of individual differences in gratitude behavior.