10. You are less moral in the evening.

After all, morality is just another series of decisions.

In The Republic, Plato mentions a magical artifact called the Ring of Gyges,which rendered its wearer invisible. He asked: would an intelligent person still be moral if they could do anything without fear of being caught or punished? (The answer — probably not)

Turns out that it takes a lot less than mythical jewelry:

Are people more moral in the morning than in the afternoon? We propose that the normal, unremarkable experiences associated with everyday living can deplete one's capacity to resist moral temptations. In a series of four experiments, both undergraduate students and a sample of U.S. adults engaged in less unethical behavior (e.g., less lying and cheating) on tasks performed in the morning than on the same tasks performed in the afternoon. This morning morality effect was mediated by decreases in moral awareness and self-control in the afternoon. Furthermore, the effect of time of day on unethical behavior was found to be stronger for people with a lower propensity to morally disengage. These findings highlight a simple yet pervasive factor (i.e., the time of day) that has important implications for moral behavior.

The paper is behind the paywall of a journal (boooo), but the press release has more details:

In two experiments, college-age participants were shown various patterns of dots on a computer. For each pattern, they were asked to identify whether more dots were displayed on the left or right side of the screen. Importantly, participants were not given money for getting correct answers, but were instead given money based on which side of the screen they determined had more dots; they were paid 10 times the amount for selecting the right over the left. Participants therefore had a financial incentive to select the right, even if there were unmistakably more dots on the left, which would be a case of clear cheating.

In line with the hypothesis, participants tested between 8:00 am and 12:00 pm were less likely to cheat than those tested between 12:00 pm and 6:00pm — a phenomenon the researchers call the “morning morality effect.”

They also tested participants’ moral awareness in both the morning and afternoon. After presenting them with word fragments such as “_ _RAL” and “E_ _ _ C_ _” the morning participants were more likely to form the words “moral” and “ethical,” whereas the afternoon participants tended to form the words “coral” and “effects,” lending further support to the morning morality effect.

And — adding to the picture of limited willpower:

“Unfortunately, the most honest people […] may be the most susceptible to the negative consequences associated with the morning morality effect.”

This makes sense; their greater moral awareness is likely to make them more aware of moral decisions — which their honesty forces them to consider, using up yet more scarce decisions.