Does the Morning Morality Effect Hold True Only for Morning People?

We recently reported four experiments in which we found that people are less likely to lie and cheat in the morning than in the afternoon—a phenomenon we termed the morning morality effect (Kouchaki & Smith, 2014). We demonstrated that the unremarkable events of everyday living can accumulate to weaken people’s ability to self-regulate their behavior. At the close of that article, we encouraged future research to focus on “the nuances of the morning morality effect—and other subtle factors that influence everyday morality” (p. 101), and we applaud the recent work of Gunia, Barnes, and Sah (2014) for doing just that. Gunia et al. sought to further explicate the relationship between time of day and moral decision making by testing whether there is an interaction between time of day and a person’s chronotype (i.e., whether the person is a morning person or an evening person). On the basis of the results of two experiments, Gunia et al. concluded that the morning morality effect is likely to hold for morning people but not for evening people, highlighting the importance of Person × Situation fit—which results in what they call the chronotype morality effect. Overall, we are greatly encouraged by the contribution they have made to understanding the effects of time of day on morality. That said, we have several responses to their characterization of our initial article and the implications of their research for our original findings.

We certainly acknowledge that individual differences (such as chronotype) can affect the relationship between time of day and a person’s ethical behavior. Indeed, we included an individual difference measure ourselves (i.e., propensity to morally disengage) in our original work because we recognize the importance of Person × Situation influences. We therefore accept the assertion of Gunia et al. that “the fit between a person’s chronotype and the time of day offers a more complete predictor of that person’s ethicality than does time of day alone” (p. 2273), and we sincerely appreciate their efforts to increase understanding in this area. However, at this point (pending further evidence), we are hesitant to fully accept their general supposition that the morning morality effect holds true only for morning people and not for evening people.

In their Supplemental Material, Gunia et al. report that they did not find a significant main effect of time of day on ethical behavior, but they did find morning people to be more moral (on average) in the morning and evening people (on average) to be more moral in the evening (Study 2). Why did they find no main effect of time of day in their single experiment, even though we found such an effect consistently in a series of four experiments, with two different populations, using three different dependent measures of unethical behavior? It is possible that our samples simply consisted of a higher proportion of morning people, whose collective dishonesty in the afternoon significantly outweighed the dishonesty of evening people in the morning. However, this seems unlikely, because our samples of university students and Amazon Mechanical Turk users were quite similar to those of Gunia et al. (2014). Alternatively, we suspect that two methodological differences probably combined to lead to the discrepant findings. Gunia et al. briefly mention these differences in a footnote to their online Supplemental Material, but we feel they are significant enough to be discussed in more detail.

First, Gunia et al. included only morning and evening people in their analysis, excluding a third of participants reporting an intermediate chronotype. We would predict that the depletion of self-regulatory resources over the course of a day would indeed affect individuals with an intermediate chronotype. Their exclusion from the sample might have reduced the likelihood of finding a main effect of time of day. Second, the differences in timing between Gunia et al.’s morning and evening sessions were much more extreme than ours. Whereas their morning sessions ran from 7:00 to 8:30 a.m. and their evening sessions from midnight to 1:30 a.m., our sessions were timed to reflect more typical working hours. Our morning sessions were conducted between 8:00 and 11:00 a.m., and our afternoon sessions between 3:00 and 6:00 p.m. We contend that it is still possible that evening people (all other things being equal) are susceptible to the morning morality effect during typical daytime hours (i.e., they behave less ethically as the day wears on because of the depletion of self-regulatory resources), but that later into the night—when energy from circadian processes may be at its peak—the effects of resource depletion are counteracted.

Finally, Gunia et al. do not provide a clear explanation of the processes or mechanisms by which a lack of fit leads to a reduction in ethicality. If the mechanism is similar to that which we proposed for the morning morality effect (i.e., the depletion of self-regulatory resources), we would expect performance on cognitive tasks to be similarly hindered by poor Chronotype × Time-of-Day fit—something Gunia et al. did not observe in their Study 1 (see their Supplemental Material). Perhaps, then, there is an affective or motivational argument for why they found morality but not performance of a cognitive task to be affected by fit. We believe this is an extremely interesting and important area for future research.

In conclusion, we commend Gunia et al. for contributing to this emerging line of research. Their findings help raise important questions that, when answered, will increase understanding of the influence of time of day on ethical decision making. Specifically, future research should address whether chronotype affects morality during the course of typical working hours or only in the early morning and late evening. Do evening people, like morning people, wear down (in terms of morally relevant self-regulation) during the early afternoon? What are the mechanisms that lead to the observed chronotype morality effect, and why do they not lead to a chronotype performance effect? Exploring these and related questions will help refine understanding of the role of time of day in people’s moral and immoral behavior.