Truth serums are something of a staple in scifi and fantasy. They even exist in real life. But now, scientists have found a new way to induce spontaneous truth telling: magnetic fields. What's more, these fields can not only increase your propensity to tell the truth — they can also turn you into a liar.
Studies that look at brain activity when a person lies have revealed several regions of the brain correlated with deceit. But correlation and causation are two very different things; as researchers Inga Karton and Talis Bachmann point out in their recently published paper, "the activation of a cortical area during lying as a correlation cue does not prove a causal relationship between it and the occurrence of lying."
But what if you could influence a person's tendency to lie by targeting these cortical areas directly — wouldn't that solidfy the case for their involvement in the lying process? The researchers explain:
[If manipulating] the state or activity of a certain area by transcranial stimulation artiﬁcially [changed] propensity to lying, we would be a step closer to unraveling the mechanisms involved in lying.
In other words, if truthfulness or lying could be induced, by targeting one of these associated brain regions directly, it could provide even deeper insight into that region's role in the process of deceit. And the researchers did precisely that. How they did it, though, is genuinely bizarre.
Volunteer test participants were subjected to something called "transcranial magnetic stimulation," or TMS for short. TMS uses electromagnetic induction to generate a magnetic field capable of polarizing specific neurons, effectively increasing or dampening activity in specific regions of the brain.
TMS was used to suppress activity in the dorsolateral prefrontal cortex (DLPFC), an area of the brain shown to be related to deceptive behavior.
Test subjects were then shown a colored disc on a computer screen. Volunteers were given the option to either lie about the color of the disc, or answer truthfully. The results were nothing short of incredible. According to the researchers:
We show that when subjects can name the colour of presented objects correctly or incorrectly at their free will, the tendency to stick to truthful answers can be manipulated by stimulation targeted at dorsolateral prefrontal cortex. Right hemisphere stimulation decreases lying, left hemisphere stimulation increases lying. Spontaneous choice to lie more or less can be influenced by brain stimulation.
In other words, not only could the researchers decrease the test participants' tendency to lie spontaneously, they could actually increase it as well; suppression of the left DLPFC led to volunteers giving significantly fewer truthful answers, while suppressing the right DLPFC had the opposite effect.
The researchers only tested 16 volunteers, and willingly acknowledge that future studies will need be more rigorous, both in the number of test participants and the method of study (many investigations into deceptive behavior look at brain activity of test participants who have a reason to lie — in a mock crime scenario, for example).
But don't let that keep you from slapping a fridge magnet on the forehead of your next interrogation subject — just make sure you place it over their right hemisphere.
The researchers' findings are published in the latest issue of Behavioural Brain Research