Investigating the morning morality effect and its mediating and moderating factors

Dishonest behavior is a prevalent phenomenon, and recent studies have suggested that seemingly trivial factors, such as the time of the day, can influence individuals' propensity to act dishonestly. Specifically, research has identified a phenomenon known as the Morning Morality Effect, where participants exhibit greater dishonesty during the afternoon or evening than in the morning. However, recent investigations have questioned the validity of this effect and its theoretical basis, with limited high-powered replications to support its existence. This conceptual replication revisited the morning morality effect and its possible mediating factors, including self-control and subjective sleepiness, and moderating factors, including chronotype, unhealthy sleep, age, caffeine intake, and honesty-humility. We conducted an online study across N = 1006 UK-based participants who were randomly allocated to perform a repeated die roll task during morning or evening hours, while also controlling for their chronotypes. Our study revealed the absence of evidence for a morning morality effect (OR = 1.04 [95 % CI 0.93, 1.17]) when testing it against a practically meaningful effect, which was also supported when meta-analyzing the current and previous studies (d = 0.04 [−0.01, 0.10]). We did not observe significant effects for any of the proposed mediators or moderators. Exploration revealed some evidence that higher levels of self-control in the evening for evening chronotypes were associated with higher die roll reports. Altogether, the current study calls the morning morality effect further into question and appeals for more valid and concrete theorizing on the link among time of the day, self-control, and dishonesty.