scorecardresearch Skip to main content
Ideas | Kelly Kasulis

Exploring truth and mind control


It’s not exactly a truth serum, but scientists might have figured out how to make us more honest. A recent study conducted at the University of Zurich in Switzerland hooked wired electrodes up to university students’ heads and ran a weak electrical current through them. They aimed the technology, called transcranial direct current stimulation — tDCS for short — at the right dorsolateral prefrontal cortex, a region of the brain that is an especially active zone when people are contemplating whether or not they should lie for their own financial gain. To test how they could manipulate that decision-making process, scientists tempted each student with potential earnings equivalent to about $90.

“They have a relatively high incentive [to lie]. . . For students, $90 can go quite a long way,” said Alain Cohn, a lead author on the study and a postdoctoral scholar at the University of Chicago Booth School of Business. He and other researchers asked students hooked up to tDCS machines to roll a die 10 times and record their numbers. For every 1, 3, or 6 rolled, for example, students would get $9.

Because probability dictates that students should only get a $9 number about half of the time, wins reported at rates higher than 50 percent suggested a liar.

The good news? “People are typically very honest, even though there were no consequences to cheating,” Cohn said. Only 37 percent of participants bluffed for more money, and that’s unusually high compared to previous experiments. Meanwhile, applying electrical stimulation to liars’ brains reduced cheating by about 60 percent.


Here’s how that works: The electrical current allows different regions to more rapidly exchange information. When most of us mentally work through the dilemma of whether or not we should lie for money, the right dorsolateral prefrontal cortex shows increased neural activity. Zapping the brain can boost that activity and tip the scale toward honesty.

“It’s an actual manipulation of the brain state,” said Joshua Greene, a professor of psychology at Harvard University. “There are two ways to be honest: You can do it effortlessly or you can restrain yourself. . . Any time you’re resisting an impulse [to cheat], you’re relying on this region of the brain.”

But that’s why tDCS affects people differently. Those who pathologically lie don’t experience as much neural activity — it’s an easy decision for them, as it is for people who consistently tell the truth. The vast majority of people — who contemplate choices to lie or tell the truth — are the most manipulated by tDCS.


Scientists were quick to say that this isn’t necessarily a slippery slope to mind control or unethical interrogations. But it really is a big step towards understanding how the mind works, honest.

Kelly Kasulis is a freelance journalist. Follow her on Twitter: @KasulisK.