Ulterior Motives

How goals, both seen and unseen, drive behavior

Darkness makes the heart grow more selfish

You are less honest and more selfish in the dark.

Robert CrayThe blues artist Robert Cray once sang, "I know the difference between wrong and right. Don't make no difference in the middle of the night." A prominent feature of the night is that it is dark. Does that have any affect on people's behavior?

A paper in the March, 2010 issue of Psychological Science by Chen-Bo Zhong, Vanessa Bohns, and Francesca Gino suggests that people are much more prone to cheat and to be selfish when it is dark than when it is light.

In one study, participants entered a room as a group and took a test consisting of 20 difficult problems. When they got to the study, they were also given an envelope with an answer key to the test and money for a bonus. Participants were asked to score their own performance on the test and to pay themselves 50 cents for each correct answer. They were to write the number of answers they got correct on the answer key and take the amount of money they were owed for their performance.

Half of the participants in this study did the study in a well-lit room and the other half did the study in a poorly lit room.

The people in the dimly-lit room cheated more than those in the well-lit room. They took more money than they deserved and they over-reported how many items they got correct.  About 60% of the people in the dimly-lit room cheated, but only about 20% of the people in the well-lit room cheated.

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A second study showed that people were also more selfish in the dark. In this study, people were given either dark sunglasses to wear (in a well-lit room) or they were given clear glasses to wear. As a part of this study, people played the "dictator game" in which they were given $6 and were asked to split that money with an anonymous partner. They were told that they could keep as much of the $6 as they want and they could give away as much as they wanted. People gave away over $1 less when they were wearing sunglasses than when they were wearing clear glasses.

Why does this happen?

In these studies, people could still be identified. The dimly lit room was dim, but not totally dark (otherwise, people could not have taken the test). Those wearing sunglasses were sitting in a well-lit room, so the room only looked dark to them.

Street lamp in the darkYet, being in the dark (or at least perceiving darkness) made people feel more anonymous. In the study with the glasses, participants rated how anonymous they felt. Those ratings were higher for those wearing sunglasses than for those wearing clear glasses. In addition, statistical analyses that looked at the relationship between the feeling of anonymity and the offers made in the dictator game showed that people offered less money (and therefore acted more selfishly) the more anonymous they felt. This feeling of anonymity explained the difference between those wearing sunglasses and those wearing clear glasses.

So, darkness not only covers your tracks, but it makes you feel as though you can't be identified. Of interest, this sense of anonymity can make people more likely to act in their own self-interest.

This reminds me of a conversation I had with my father when I was young. We passed by a house that had a large glass window on its front door. The door also had a prominent lock on it. I wanted to know why anyone would put a lock on a big glass door, when you could just break the window and open the door from the inside. He replied that anyone intent on getting into your house would find a way to break in no matter how well it was locked up. The lock was there to keep the honest people honest.

And the light also helps to keep the honest people honest.

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Art Markman, Ph.D., is a cognitive scientist at the University of Texas whose research spans a range of topics in the way people think.

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