Ever hear the joke about the lying economist?

No? Well, neither have I. But we might need to come up with one.

Such is the takeaway from a working paper released in January, which I stumbled on while browsing Professor Andres Marroquin's top studies of 2012. Written by a pair of researchers from universities in Montreal and Madrid, it examined whether the study of economics made students more apt to lie for financial gain. The answer: a resounding yes.

Several past experiments have tried to test how people's personal beliefs and background influence their willingness to lie, and one, published in 2009, yielded results suggesting that economics students were more likely to fib than those in other disciplines. Raul Lopez-Perez and Eli Spiegelman -- both economists themselves -- wanted to find out if those findings would hold up in another lab setting ... and if they did, exactly why that might be the case. Were econ students over-internalizing the lessons of the dismal science, which teaches that human beings are supposed to act in their rational self interest? Or were dishonest young folks just more likely to sign up for econ classes in the first place?

To find out, Lopez-Perez and Spiegelman designed an experiment that gave its subjects every conceivable incentive to lie, and none to tell the truth -- unless, of course, they simply felt that was the moral thing to do. The test involved two participants, one we'll just call the "decision maker" and one we'll call "the other guy." Each decision maker sat in front of a computer screen that would flash either a blue or a green circle. They then had to send a message to the other guy informing them what color had appeared. If the decision maker reported that the circle was blue, he or she received 14 euros. If they reported that it was green, they received 15 euros. In other words, whenever a blue circle popped up, they were forced to choose between being honest or making an extra euro by claiming it was green. The researchers, however, did the best to make that choice simple. No matter what the decision maker reported, the other guy always received 10 euros and never got to learn what color actually showed up on screen. All of these rules were clearly laid out for both people in the experiment.