“Our findings show that people typically find truth-telling to be more rewarding than lying in different types of deceptive situations,” said Kang Lee, Ph.D., from the University of Toronto.
The researchers conducted two studies using a new neuroimaging method called near-infrared spectroscopy, monitoring the brain activity of volunteers from China. Near-infrared spectroscopy is similar to functional magnetic resonance imaging (fMRI), but can scan only cortical tissue of the brain, not glucose levels as an fMRI does. Near-infrared spectroscopy, however, is more portable, because it simply measures near-infrared region of the electromagnetic spectrum.
The studies explored two different types of deception. In the first, the recipient does not know the deceiver is lying. In the second, the deceivers are fully aware that the recipient knows their intentions, such as bluffing in poker.
The researchers said they were surprised to find that a liar’s cortical reward system was more active when a reward was gained through truth-telling than lying. This was true in both first- and second-order deception, they report.
They also found that, in both types of deception, telling a lie produced greater brain activations in the frontal lobe than telling the truth. This suggests lying is cognitively more taxing than truth-telling and uses more neural resources, according to the researchers.
The researchers said they hope the study will advance understanding of the neural mechanisms underlying lying, and help to diagnose pathological liars who may have different neural responses when lying or telling the truth.
The studies were published in the neuroscience journals Neuropsychologia and NeuroImage.
Source: University of Toronto