Do you reject the idea of free will and believe that your actions are determined? If so, it turns out that you are more likely to cheat. Conversely, the more you believe in free will, the more you are likely to exercise responsibility and make choices you can feel good about.
Kathleen D. Vohs (University of Minnesota) and Jonathan W. Schooler (University of British Columbia) recently published a report in Psychological Science (19/1, Dec 26, 2007, 49-54) describing two studies that suggest this conclusion.
The studies were centered around priming experiments. Participants were subtly primed–either with a belief that free will does not exist, or with a neutral prime. They were then asked to perform an action that allowed for the possibility of cheating without consequence. Participants who received the “no free will” prime were significantly more likely to cheat.
For more information, read the New York Times article.