We are all more likely to commit immoral acts in the afternoon than in the morning. That is the conclusion of a new study from Harvard University, where researchers have determined that personal ethics and moral behavior tend to diminish later in the day. After lunch, more people fail to resist the temptation of cheating, stealing, and lying.

The study, which is published in the journal Psychological Science, sought to investigate a curious pattern that the authors had noticed in previous research efforts. Reviewing several studies designed to emulate moral dilemmas, the researchers discovered that the average test subject was more likely to break away from norms during experiments conducted in the afternoon than those conducted in the morning. According to lead author Maryam Kouchaki, the strange link appeared to persist as more experiments were taken into account.

"As ethics researchers, we had been running experiments examining various unethical behaviors, such as lying, stealing, and cheating," she said in a press release. "We noticed that experiments conducted in the morning seemed to systematically result in lower instances of unethical behavior."

To investigate this phenomenon, the researchers enrolled a number of college-age volunteers in an experiments designed to assess morality and adherence to ethical rules. In the first experiment, participants were shown various patterns of dots on a computer screen and asked to determine whether more dots were displayed on the right or left side. Rather than compensating correct answers, the researchers gave the participants money for each submitted answer. However, the researchers always awarded a significantly higher amount for answers indicating the right side of the screen, giving participants financial incentive to choose that side even when more dots appeared on the left.

Intriguingly, the team found that participants tested between 8:00 a.m. and noon were significantly less likely to cheat and take the higher award compared to participants tested between noon and 6:00 p.m. Although the Kouchaki and her team have yet to figure out the psychology underpinning this “morning morality effect,” they are confident that an awareness of the strange phenomenon will be of use to many large employers. After all, compliance strategies would necessarily be improved if company policy writers knew when immoral acts usually take place.

"For instance, organizations may need to be more vigilant about combating the unethical behavior of customers or employees in the afternoon than in the morning," the researchers explained. "Whether you are personally trying to manage your own temptations, or you are a parent, teacher, or leader worried about the unethical behavior of others, our research suggests that it can be important to take something as seemingly mundane as the time of day into account."

Source: Kouchaki M, Smith IH. The Morning Morality Effect: The Influence of Time of Day on Unethical Behavior. Psychological Science. 2013.