Don't Even Think About Lying I'm flat on my back in a very loud machine, trying to keep my mind quiet. It's not easy. The inside of an fMRI scanner is narrow and dark, with only a sliver of the world visible in a tilted mirror above my eyes. Despite a set of earplugs, I'm bathed in a dull roar punctuated by a racket like a dryer full of sneakers.
Functional magnetic resonance imaging - fMRI for short - enables researchers to create maps of the brain's networks in action as they process thoughts, sensations, memories, and motor commands. Since its debut in experimental medicine 10 years ago, functional imaging has opened a window onto the cognitive operations behind such complex and subtle behavior as feeling transported by a piece of music or recognizing the face of a loved one in a crowd. As it migrates into clinical practice, fMRI is making it possible for neurologists to detect early signs of Alzheimer's disease and other disorders, evaluate drug treatments, and pinpoint tissue housing critical abilities like speech before venturing into a patient's brain with a scalpel.
Now fMRI is also poised to transform the security industry, the judicial system, and our fundamental notions of privacy. I'm in a lab at Columbia University, where scientists are using the technology to analyze the cognitive differences between truth and lies. By mapping the neural circuits behind deception, researchers are turning fMRI into a new kind of lie detector that's more probing and accurate than the polygraph, the standard lie-detection tool employed by law enforcement and intelligence agencies for nearly a century.
The polygraph is widely considered unreliable in scientific circles, partly because its effectiveness depends heavily on the intimidation skills of the interrogator. What a polygraph actually measures is the stress of telling a lie, as reflected in accelerated heart rate, rapid breathing, rising blood pressure, and increased sweating. Sociopaths who don't feel guilt and people who learn to inhibit their reactions to stress can slip through a polygrapher's net. Gary Ridgway, known as the Green River Killer, and CIA double agent Aldrich Ames passed polygraph tests and resumed their criminal activities. While evidence based on polygraph tests is barred from most US trials, the device is being used more frequently in parole and child-custody hearings and as a counterintelligence tool in the war on terrorism. Researchers believe that fMRI should be tougher to outwit because it detects something much harder to suppress: neurological evidence of the decision to lie.
My host for the morning's experiment is Joy Hirsch, a neuroscientist and founder of Columbia's fMRI Research Center, who has offered me time in the scanner as a preview of the near future. Later this year, two startups will launch commercial fMRI lie-detection services, marketed initially to individuals who believe they've been unjustly charged with a crime. The first phase of today's procedure is a baseline interval that maps the activity of my brain at rest. Then the "truth" phase begins. Prompted by a signal in the mirror, I launch into an internal monologue about the intimate details of my personal life. I don't speak aloud, because even little movements of my head would disrupt the scan. I focus instead on forming the words clearly and calmly in my mind, as if to a telepathic inquisitor.
Then, after another signal, I start to lie: I've never been married. I had a girlfriend named Linda in high school back in Texas. I remember standing at the door of her parents' house the night she broke up with me. In fact, I grew up in New Jersey, didn't have my first relationship until I went to college, and have been happily married since 2003. I plunge deeper and deeper into confabulation, recalling incidents that never happened, while trying to make the events seem utterly plausible.
I'm relieved when the experiment is over and I'm alone again in the privacy of my thoughts. After an hour of data crunching, Hirsch announces, "I've got a brain for you." She lays out two sets of images, one labeled truth and the other deception, and gives me a guided tour of my own neural networks, complete with circles and Post-it arrows.
"This is a very, very clear single-case experiment," she says. In both sets of images, the areas of my cortex devoted to language lit up during my inner monologues. But there is more activity on the deception scans, as if my mind had to work harder to generate the fictitious narrative. Crucially, the areas of my brain associated with emotion, conflict, and cognitive control - the amygdala, rostral cingulate, caudate, and thalamus - were "hot" when I was lying but "cold" when I was telling the truth.
"The caudate is your inner editor, helping you manage the conflict between telling the truth and creating the lie," Hirsch explains. "Look here - when you're telling the truth, this area is asleep. But when you're trying to deceive, the signals are loud and clear."
I not only failed to fool the invisible inquisitor, I managed to incriminate myself without even opening my mouth.
The science behind fMRI lie detection has matured with astonishing speed. The notion of mapping regions of the brain that become active during deception first appeared in obscure radiology journals less than five years ago. The purpose of these studies was not to create a better lie detector but simply to understand how the brain works.
One of the pioneers in the field is Daniel Langleben, a psychiatrist at the University of Pennsylvania. Back in 1999, he was at Stanford, examining the effects of a drug on the brains of boys diagnosed with attention deficit hyperactivity disorder. He had read a paper theorizing that kids with ADHD have difficulty lying. In Langleben's experience, however, they were fully capable of lying. But they would often make socially awkward statements because "they had a problem inhibiting the truth," he says. "They would just blurt things out."
Langleben developed a hypothesis that in order to formulate a lie, the brain first had to stop itself from telling the truth, then generate the deception - a process that could be mapped with a scanner. Functional imaging makes cognitive operations visible by using a powerful magnetic field to track fluctuations in blood flow to groups of neurons as they fire. It reveals the pathways that thoughts have taken through the brain, like footprints in wet sand.
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