Researchers Find New Technique To Detect Lies By Looking At Someone's Brain Activity

by Aruna on Jul 17 2009 9:32 AM

Researching into the cognitive process involved with honesty researchers say that truthfulness depends more on absence of temptation than active resistance to temptation.

Harvard University psychologists, Assistant Professor Joshua Greene and graduate student Joe Paxton, the duo that led the study, have revealed that they used neuroimaging to look at the brain activity of people given the chance to gain money dishonestly by lying, and found that honest people showed no additional neural activity when telling the truth.

The researchers say that that observation implied that extra cognitive processes were not necessary to choose honesty.

However, the researchers also found that individuals who behaved dishonestly, even when telling the truth, showed additional activity in brain regions that involve control and attention.

"Being honest is not so much a matter of exercising willpower as it is being disposed to behave honestly in a more effortless kind of way. This may not be true for all situations, but it seems to be true for at least this situation," says Greene.

The researchers say that they carried out the study to test two theories about the nature of honesty - the "Will" theory, in which honesty results from the active resistance of temptation, and the "Grace" theory in which honesty is a product of lack of temptation.

Writing about their findings in the journal Proceedings of the National Academy of Sciences, they have suggested that the "Grace" theory is true, because the honest participants did not show any additional neural activity when telling the truth.

To prompt participants to lie, the researchers created a cover story about the focus of their study. The research was presented as a study of paranormal ability to predict the future.

The researchers asked those participating in the study to predict the outcomes of a series of coin tosses.

The subjects were told that the research team believed predicting the future was more likely when given a monetary incentive, and when the prediction was not shared in advance of the outcome. That gave the participants the opportunity to lie and say that they had correctly predicted the coin toss to win the money.

The subjects' honesty was assessed based on whether their number of correct responses was statistically feasible.

According to the researchers, the participants who reported improbably high levels of accuracy were classified as dishonest, and those reporting statistically feasible levels of accuracy were classified as honest.

With the aid of fMRI technique, Greene found that the honest individuals displayed little to no additional brain activity when reporting their prediction of the coin toss. However, the dishonest participants' brains were most active in control-related brain regions when they chose not to lie.

Greene notes that there was an important distinction between the brain activity when the honest participants told the truth, and when the dishonest participants told the truth.

"When the honest people leave money on the table, you don't see anything special or extra going on in their brains at all. Whereas, when the dishonest people leave money on the table, that's when you saw the most robust control network activation," says the researcher.

The researchers hope that their findings may pave the way for a technique to detect lies by looking at someone's brain activity, but they also concede that a lot more work must be done before this becomes possible.