Zap one part of the brain with a magnetic pulse and people become more likely to lie. Stimulate the opposite side of the region and truth-telling increases, according to new research.
In the study, 16 participants were asked to view red or blue colored disks on a computer monitor and, at their own discretion, to sometimes lie about the color and identify red as blue, or vice versa.
While the volunteers made these choices, researchers applied repetitive transcranial magnetic stimulation (rTMS) to their brains. The small rTMS device uses magnets to generate weak electrical fields, and researchers place it near the head to administer the non-invasive pulses. This affects communication between brain cells in targeted regions.
Doctors use rTMS as a treatment for depression that fails to respond to drugs or therapy, and it is also being studied for other psychiatric and neurological disorders. Side effects can include some twitching, but the treatment is not generally reported to be painful.
In the new study, researchers administered rTMS to the dorsolateral prefrontal cortex — a region involved in planning, memory and self-control — either in the right or left hemisphere of the brain. When rTMS was used on the right hemisphere, participants were more likely to tell the truth. When the stimulation was applied to the left side of that region, the probability of lying increased. Stimulation applied to other brain regions in the study’s control participants had no effect on their honesty.
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Because the number of participants was so small, it’s hard to draw firm conclusions from the research. Even if the study were replicated in a much larger group, however, it might not translate directly to the real world. Stimulation of the brain could have a different effect when the stakes of lying — say, to avoid being sent to prison — are higher than simply participating in an experiment. The brain’s responses to experience are different depending on the person’s emotional state.
Nonetheless, the potential ability to detect or even control people’s deceitfulness would be of tremendous interest to those working in professions like law or national security—as well as having terrifying civil liberties implications. Study co-author Talis Bachmann of the University of Tartu in Estonia spoke with the U.K.’s Guardian about the potential legal repercussions of using rTMS to get people to tell the truth:
Provided that the method is validated and legal norms are established, it could perhaps be allowed and justified … but this should not become a routinely used technique. Basic human rights include cognitive privacy and this would be a clear infringement. If a subject freely agrees, maybe it would make sense, but I foresee heated debates on whether ‘knocking truth out of the fellow’ can be legalized in principle.
Quite an understatement, I’d say! Let’s hope the ethicists keep close tabs on this technology.
The study was published in Behavioral Brain Research.
[h/t: Mo Costandi of the Guardian’s excellent Neurophilosophy blog]
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Maia Szalavitz is a health writer at TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland’s Facebook page and on Twitter at @TIMEHealthland.