Although every lie detector ever built has proved unreliable, scientists continue to search for that magic machine that will reveal dishonesty. Now two Harvard neuroscientists have hit on a "pre-crime" technique that reveals intent to lie before it happens.


While some people already think that brain-imaging lie detectors are a scam, others remain convinced that they're the wave of the future. A recent study by Joshua Greene and Joseph Paxton at Harvard University shows that the skeptics might be right.


Paxton and Greene bet their subjects money based on guessing a coin flip. While those who had to record their responses in advance had average success, those who didn't have to tell their guess until after they knew the result had a high success rate, indicating they were lying. More interestingly, those people who were even interested in lying showed brain activity when just offered the opportunity to cheat, while those who were more honest showed no difference in their brain activity regardless of the opportunity to cheat. Over time, Greene and Paxton were able to predict whether certain volunteers would lie at all. They expect that their machine could be developed not just to determine whether someone was lying or had lied, but if they were interested in doing so or would in the future.

You always knew your brain would eventually betray you. The question is, how useful is this information really? Doesn't everyone want to lie sometimes, including people who are honest?

Truthfulness Requires No Act of Will for Honest People [via Harvard]

[Image via the Arnold School of Public Health]