Sniffing Out Liars

Can science help us determine if someone is deceiving us?
The very high-tech stuff we rely on includes functional magnetic resonance imaging, magnetic encephalography, and some very, very sophisticated electroencephalography—one of the techniques used to test so-called guilty knowledge. That’s where you expose somebody to something and they have guilty knowledge—they’ve seen it before, let’s say. You can tell by looking at their brain response, up to a point, whether their brain has seen that thing or not. You say, well, do you know X, or have you seen X, and they say no, but their brain says otherwise.