Exploring the Morning Morality Effect in the context of moral utilitarianism: a post-hoc analysis

Recent research has shown mixed evidence for the morning morality effect (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, by reanalyzing observational data previously collected by our lab. These data include different tasks capturing moral utilitarianism (i.e., standard sacrificial dilemmas, an ecological utilitarian scale, and/or dilemmas involving the morality of autonomous vehicles). We report a meta-analysis of 6 studies which showed that participants became less utilitarian as the day goes on, but with a small effect size (r = -0.14) and a large heterogeneity. Exploration of this heterogeneity showed that such a conclusion was statistically significant for classic sacrificial dilemmas only. Notably, even when restricting the analysis to the classic sacrificial dilemmas, a moderate inconsistency remained. Post-hoc analysis of an individual study showed that this small effect did not survive the inclusion of potentially confounding variables, such as psychopathy trait and cognitive reflection. Implications and limitations are discussed.