Self-control Decreases as Day Wears On

Self-control is easier to muster in the morning than the afternoon, a new study published in Psychological Science found.

After noticing that experiments carried out in the morning routinely produced lower instances of unethical behavior, Maryam Kouchaki of Harvard University and Isaac Smith of the University of Utah decided to examine whether or not the time of day plays a role in a person's level of self-control.

They ran an experiment in which college-age participants were shown a variety of patterns of dots on a computer and asked to identify the side containing more dots. Rather than giving participants money based on choosing the correct side, however, the researchers paid the participants 10 times more whenever they selected the right side over the left. Sure enough, participants tested between 8:00 a.m. and 12:00 p.m. accurately reported the side with the most dots more often than those who tested between 12:01 p.m. and 6:00 p.m.

In a second experiment, researchers tested the participants' moral awareness by presenting them with the words "moral" and "ethical," but with missing letters. The participants were then asked to fill in the blanks to form the word. The results showed that individuals were more likely to form the words "moral" and "ethical" in the morning, while the afternoon participants tended to form "coral" and "effects."

Looking beyond the college campus, the scientists examined a sample of online participants from across the United States who, like the students, exhibited less self-control as the day wore on. This was seen in their tendency to send more dishonest messages to a virtual partner or more frequently report having solved an unsolvable number-matching problem in the afternoon compared to the morning.

The individuals most susceptible to this pattern were those with a lower propensity to morally disengage, or to behave unethically without feeling guilt or stressed, the researchers found. This is because those with a high tendency to morally disengage were similarly unethical in the morning and afternoon.

"Unfortunately, the most honest people, such as those less likely to morally disengage, may be the most susceptible to the negative consequences associated with the morning morality effect," the researchers write. "Our findings suggest that mere time of day can lead to a systematic failure of good people to act morally."