Zhong, C., Bohns, V. K., & Gino, F. (2010).Good lamps are the best police: Darkness increases dishonesty and self-interested behavior. Psychological Science, 21(3), 311-314. In this article, the experimenters were interested in exploring whether darkness increases dishonesty and self-interested behavior. In particular, they wanted to investigate whether darkness induced a sense of illusory anonymity – a sense of concealment and hidden identity derived solely from the dimness in the environment that is independent of actual anonymity – whether other people were able to see or identify an individual when he is performing a particular action or not; and if so, whether this sense of illusory anonymity in turn led to dishonesty and self-interested behavior. The experimenters conducted three experiments that sought to investigate their hypothesis that darkness increases dishonesty and self-interested behavior via the mediating effects of illusory anonymity. The first experiment involved undergraduates at one university completing a problem-solving task of matching pairs of numbers in matrixes as instructed and self-reporting their own performances to earn actual monetary pay-offs. The task was designed to appear to be completely anonymous, and care was taken to ensure that the time limit given did not allow participants to solve all problems given. Unbeknownst to participants, however, each of their problem sheets contained a unique identification digit that would then be matched up with that on their performance reports to track actual performance, reported performance and any differences between these values. The experimenters manipulated the independent variable of the brightness (dimness) of the experiment rooms: participants were randomly assigned to a room lit with 12 fluorescent bulbs (control/bright room condition) or with four fluorescent bulbs (dim room condition) before being given the problem-solving task and instructions. The major dependent variable measured in this experiment was differences between actual performance and reported performance as evidence of cheating – a form of dishonesty and self-interested behavior.
Consistent with the hypothesis, participants in the dim room condition cheated significantly more than participants in the control room condition. Specifically, both the percentage of participants that cheated (i.e. occurrence of cheating) and the average difference between a participant’s actual performance and reported performance (i.e. magnitude of cheating) were higher in the dim room condition than in the control room condition. This means that although both groups were given the opportunity to cheat (the task appeared completely anonymous to participants) and the incentive to cheat (monetary rewards), participants in the dim room cheated significantly more those in the well-lit room. These findings suggest that the mere dimness of the environment can cause greater dishonesty.
The second experiment involved undergraduate students from another university participating in an exercise where each participant was told to take the initiative to split an amount of $6 between himself and “another participant in the next room” via typing his decision into a computer. Here, too, participants were led to believe their actions were completely anonymous as they were alone when typing in their decisions and no interactions took place between participants. Unbeknownst to the participants, however, their responses in the computer program were being tracked by the experimenters. The independent variable in this experiment was the level of darkness experienced by the participants: they were randomly assigned to either wear sunglasses (dark condition) or clear glasses (control condition) before stepping into the experiment room. The dependent variable measured was the amount of money given to “the other participant”, with lower amounts corresponding to higher tendencies of self-interested behavior.