Best lie detector – fMRI scan.

In Brain Circuitry, Brain Science, Brain Technology by Brainy Days Ahead

It turns out that our brains are much more likely to give us away than sweaty palms or spikes in our heart rates. Researchers in the Perelman School of Medicine at the University of Pennsylvania find that scanning people’s brains with fMRI, or functional magnetic resonance imaging, was significantly more effective at spotting lies than a traditional polygraph test.