Roy Baumeister and his collaborators including Matthew Gailliot of Florida State University claim that willpower has a physiological substrate – namely, blood glucose level. In a series of studies published in 2007 they showed that acts of self-control reduce people’s glucose levels and that, in turn, diminished blood glucose is associated with weaker performance on subsequent self-control tasks (PDF). Most importantly for the purpose of being less sinful, they also showed that a high-glucose energy drink can recharge willpower allowing people to be more altruistic. For example, participants who took longer over a psychology exam, and whose energy levels were therefore more depleted, went on to offer less money to charity and less help to a classmate who’d been evicted, unless, that is, they’d had a high-glucose lemonade drink after the exam. By contrast, a low-glucose placebo drink had no such beneficial effect on helping behaviour.
This post is part of the Research Digest's Sin week. Each day for Seven days we'll be posting a confession, a new sin and a way to be good. The festivities coincide with the publication of a feature-length article on the psychology behind the Seven Deadly Sins in this month's Psychologist magazine.