But a recent experiment suggests that one's ability to tell the truth or lie can be influenced by something as different from human nature as a strategically placed magnet.
Researchers in Estonia showed that when a magnet is applied to the dorsolateral prefrontal cortex, the area just behind one's forehead (see diagram below), it can either increase or decrease one's propensity to lie. Let's just nickname this part of the brain, which has long been thought to control decision-making and complex thought, the DPC.
Inga Karton and Talis Bachmann targeted the DPC with transcranial magnetic stimulation, which is often used by researchers to stimulate some parts of the brain while leaving the rest of it alone. Scientists often use the technique to study elusive qualities of human nature, such as morality and memory. The stimulation temporarily interferes with the functionality of the affected area, probably by slowing or numbing it.
The DPC is divided into left and right halves. In the experiment, 16 volunteers received the magnetic stimulation on one side or the other.
They were then shown colored discs on a computer screen that were either red or blue. The researchers asked them to lie about the color of some of the discs and to be honest about the color of others.
The eight volunteers who received the magnetic stimulation on the left side of the DPC lied less often, while the eight who got the magnetic touch on the right side of the DPC lied more often.
There are two caveats to the results, which were published in Behavioural Brain Research. First, a sample size of 16 subjects is hardly reason for police to toss polygraphs and buy transcranial magnetic stimulation machines. Second, who knows what would happen if the subjects were personally motivated to lie. Would having something at stake overcome any restraining influence from the magnet?
Still, given these results from this small sample size, more research is likely to be done in this area. As Popular Science points out:
Most studies of deceptive behavior have examined brain activity during mock thefts or pretending not to recognize objects, the researchers write. Here, the subjects had no “criminal” reason to lie, yet they did anyway; the researchers were able to study the brain regions responsible for this behavior.
Further studies could influence how truth-seekers such as the police get would-be liars to tell the truth -- and how Hollywood portrays cop shows.
Brain illustration: Was a bee/Wikimedia