In our first experiments, we took students and measured how creative they were using multiple methods. No matter the measure, we found that the more creative people cheated more on a math test.
Second, we tried to temporarily increase creativity in some people but not in others. There are all kinds of evidence that this works. [For tips on boosting creativity, see “Your Creative Brain at Work,” by Evangelia G. Chrysikou; Scientific American Mind, July/August 2012.] Those in whom we increased creativity cheated a bit more. That's more causal, supporting the idea that creativity is the mechanism.
Then we went to a big advertising company and asked its employees questions that tested their moral flexibility in personal relationships, taxes, relationships with companies, and so on. If you were on a business trip, would you report a dinner you purchased after you got home on your expense report? We also asked the CEO which jobs have more or less creativity. The results showed that the more creativity in a person's job, the more moral flexibility the person reported in our survey.
Creativity is very helpful for lots of things, so we don't want to stamp it out. But if you take creative people and put them in a situation where they have a conflict of interest and where the rules are flexible, this is going to be a bad recipe. Wherever rationalization is easy, I would worry a lot about the rules, regulations and code of conduct—and then I would try to eradicate conflict of interest. In finance, you can make lots of money if you see reality in one way or another. In medicine, if a physician gets paid for prescribing a test or procedure, creativity can also play a big dangerous role. And there are cases where creativity exercises might not be beneficial. I would also worry about increasing creativity just before doing taxes or playing golf.
Not all dishonesty is bad. We all know about white lies and social politeness. Telling the truth all the time is a difficult thing to live with, which is why we often encourage some level of dishonesty.