"And they would argue that (with) fMRI, since it's scanning the brain, we're getting closer to the central nervous system, not dealing with the peripheral nervous system. We're dealing with what some say is 'the organ of deceit' where the lies are happening."
But according to Littlefield, the old and the new deception-detection tools basically rely on the same three assumptions.
"The first one is that lies are somehow measurable that you can see them in the body through increased breathing, heart rate or by looking at the brain." In the latter case, she said, "colloquially, people say 'your brain lights up' in the fMRI scanner."
The second common assumption, she said, is that "when you look at the body and get some kind of information whether it's pulse rate or blood oxygenation level dependent (BOLD) signals, or whatever it is that each is measuring that somehow you're able to see the body in action without needing any interpretation."
The presumption, she said, is that those viewing results of both manners of truth-seeking "somehow see the body in action without needing any interpretation like looking through a window, as opposed to looking at some kind of artistic picture that needs interpretation."
Finally, she said, "they share this assumption that truth and deception are somehow connected. In deception studies, if you're looking at the polygraph or you're looking at the fMRI, the assumption is that truth is the baseline the factual, the basic, the natural. And to lie is to add a story on top of the truth."
The "good news" in all of this, she said, is that investigators can't actually track people's intentions or behavior by scanning their brains.
"You can't put someone in an fMRI scanner and read their mind or incriminate them, at least in part, because the person would have to lie so still," Littlefield said. "Protoco
|Contact: Melissa Mitchell|
University of Illinois at Urbana-Champaign