A new study has said that people under scrutiny are more comfortable letting bad things happen rather than actively causing something bad.
This is because they know other people will think worse of them if they do something bad than if they let something bad happen.
The study might explain why you might be ok about not returning a 20-dollar bill back that the cashier gives you by mistake but not about stealing it.
"If a cashier gives you an extra 20-dollar bill at the register, some people think it's okay to keep the money, but many of those people would never just swipe the twenty if the cashier wasn't looking," said moral psychologist Peter DeScioli of Brandeis University.
While keeping the extra cash and not returning it is termed a sin of omission, stealing it is a sin of commission.
However, DeScioli and colleagues John Christner and Robert Kurzban of the University of Pennsylvania thought people were actually making a strategic decision about how to act based on how someone else might judge them.
The experiment involved people recruited through Amazon.com's Mechanical Turk website, which pays people small amounts of money to do tasks.
Each time, a "taker" had the option to take part of a dollar away from an "owner"-or to let a 15-second timer run out, in which case the whole dollar was automatically transferred from the owner to the taker, but with a 15-cent penalty leaving the owner with nothing and the taker with 85 cents.
Sometimes a third person was involved, to judge the taker's actions and take money away from them for acting badly; sometimes they weren't.
When the takers knew that someone was judging them, 51 percent of participants let the timer run out, even though this was worse for everyone than taking 90 cents.
This percentage was significantly greater than the 28 percent who let the timer run out when there was no third person judging them. Rightly so, because the third person judged them more harshly if they outright took the 90 cents than if they let the timer run out and deprived the owner of the whole dollar.
So people were more likely to do a bad thing by omission if they knew they could be punished for it.
The researchers say the study will help experts sort out the relationship between conscience-the moral decisions you make on your own-and condemnation, the negative judgments made by people who see you act.
The study is published in Psychological Science, a journal of the Association for Psychological Science.