Exploring the Morning Morality Effect in the Context of Moral Utilitarianism

Recent research has shown mixed evidence for the morning morality effect (MME; i.e., the observation that individuals are less immoral in the morning than in the afternoon). In the present research, we target the morning morality effect in the context of moral utilitarianism, for which this effect has never been explored. We first reanalyzed observational data from six studies previously conducted by our lab, which included different tasks capturing moral utilitarianism. A meta-analytic model showed that participants become less utilitarian as the day goes on, but with a small effect size (r = -0.14, 95% CI = [-0.25, -0.02]) and large heterogeneity. Exploration of this heterogeneity showed that this association was statistically significant for classic sacrificial dilemmas only. We next conducted an experimental study of the morning morality effect, which aimed to experimentally support the results previously observed in the meta-analysis, as well as to explore, in addition, a possible moderating effect of chronotype. These experimental results showed no reliable overall effect of time of day on moral utilitarianism (SMD = 0.04, 95% CI = [-0.21, 0.28]). A potential moderating effect of chronotype was detected in secondary analyses, but that needs to be replicated. The implications and limitations are discussed.