The Brain Doesn't Lie

Neuroimaging reveals whether you're bluffing or telling the truth.

Posted Nov 22, 2010

The world of business is littered with broken promises and outright lies – from the promotions that don't materialize, to the agreements that aren't worth the hands they're shaken on, to Madoff-style frauds and scams.

Wouldn't it be handy, then, to have some way to accurately predict who will keep his or her word, and who has no intention of honouring it?

There isn't a foolproof test yet. But a recent study by a team of European economists and psychologists found that, should MRI scanners ever become standard office equipment, the brains of trustworthy people will likely be found to be quite different from the brains of the dishonest.

Thomas Baumgartner, a research economist at the University of Zurich and lead investigator on the team, started with two simple questions. First, what would happen if people were offered the choice of saying whether they would always, sometimes, or never share their profits with future investment partners? Secondly, is there any difference in brain activity between those who say they will always split the profits, and then actually follow through; and those who promise they will, but then renege?

Dr. Baumgartner hypothesized that the misleading promise "should evoke an emotional conflict." This clash between what people say they will do, and what they actually do, should show up on brain scans as increased activity in the neural areas that register feelings of conflict and discomfort in social situations.

And that's exactly what the researchers found.

Nearly every one of the research subjects vowed they would always share future profits with their partners, but their real intentions weren't uniformly virtuous. When tested in an investment game, the subjects divided fairly cleanly into two groups: those who were honest and those who were deceitful. The latter group had publicly declared an intention to share, but then didn't divvy up their earnings.

Although the promise-breakers tried to bluff, brain scans revealed their duplicity. Increased blood flow was clearly visible to three neural areas that register emotional conflict: the anterior cingulate cortex, which monitors our motivations and feelings of guilt and reward in social situations; the insula, which tracks visceral feelings of unfairness and the threat of punishment; and the amygdala, a pair of neuron clusters that process and file away emotional experiences, especially those characterized by fear and stress.

The upshot is that even if we try to pull the wool over the eyes of others, brain imaging lays bare our feelings and intentions.

Of course, expensive MRI scans (and the expertise to interpret them) are unlikely to become features of the average workplace any time soon. But the neural evidence adds a layer of understanding as to how notions of honesty and deceit, guilt and honour, are expressed in our brain.

Without an MRI machine, employers have other ways to try to predict a person's behaviour on the job. Taken together, employment history, personal references and examples of successes or failures show how a person performed in the past. Non-verbal signals, such as facial expressions and body language, can also tell much about a person's true feelings.

And behavioural tests that assess honesty and integrity are increasingly popular in human resources circles. Although many such tests are rather clumsy tools, they're all we have – for now.

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