After a magnetic pulse to the brain, study subjects cannot tell a lie — or, more accurately, after transcranial magnetic and electric stimulation to the right side of the dorsolateral prefrontal cortex, subjects were less likely to lie, and after stimulation to the left they were more likely to lie:
In this study, volunteers submitted to TMS to stimulate their dorsolateral prefrontal cortex, which is thought to be involved in decision-making, complex thought and deception. Like most of the brain, it has a right and a left side, which are both responsible for different tasks. The volunteers were shown a series of colored discs, and told they could tell the truth or lie about their colors. Half were stimulated on the left, half on the right.
The eight people who had their left DPC stimulated lied more often, the researchers said. The ones with the right DPC stimulated were more likely to tell the truth. The experiment was repeated while a different brain region was stimulated, and that region, the parietal lobe, had no effect.
(Hat tip to our Slovenian Guest.)