Nervously, my heart pounding, I remove my clothing, watch, and wedding ring. No, it’s not an extramarital tryst. The only affair I’m involved in is reporting on a new form of lie detector, one that uses magnetic resonance imaging (MRI). That explains the need to shed my clothes, which might have magnetizable metal parts in them, along with the watch and ring, which could be sucked with dangerous force into the powerful magnet of the apparatus. (Accidents from flying metal have injured and even killed MRI subjects in the past.) I then don hospital garb and climb onto a platform that glides me into the heart of an impressively large if somewhat cramped scanner.
I’m here to investigate No Lie MRI, a San Diego company that is offering US $5000 “truth-verification” sessions. Around my head, a superconducting electromagnet cooled to within a few degrees of absolute zero generates a magnetic field that’s about 50 000 times as strong as Earth’s.
To the accompaniment of various clicks and clacks, a screen above my head flashes a series of questions in front of my eyes. Did I ever claim more than I should have for business expenses? Have I cheated on my wife? Have I pretended to be ill in the last year? I am tested on nine questions in all. The topics are serious enough to provoke strong emotional responses but innocent enough to save No Lie MRI from having to report me to the authorities should I appear to be covering something up. I had settled on the questions with the company beforehand and promised to provide truthful answers to all but one of them, giving No Lie MRI an 11 percent possibility of spotting my fib by chance alone.
While I’m in the machine, the questions arrive at unpredictable intervals and are repeated several times throughout the session. Control questions are shuffled in at random. After 10 minutes, my grilling is over, and the complex business of analyzing the data begins, a process that will take several days. I’ve done my best to deceive my interrogators, and they will do their best to read my mind.
No one is suggesting that such elaborate tests are suitable for petty criminal cases or regular employee screenings—especially at $5000 a pop. And the courts are far from accepting the results of such scans as evidence. But that hasn’t stopped lots of people from putting their money where their brain waves are. No Lie MRI’s clients include a store owner who wanted to prove that he did not commit arson for the insurance payout, a woman trying to convince her husband that she hadn’t been unfaithful, and a father denying allegations of child abuse.
Could this really work? A machine that could reliably separate truth from lies would be a police detective’s dream—and a civil libertarian’s nightmare. Your opinion may depend on which side of the device you’re on, but many people would like nothing better than having a truly foolproof lie detector. All that’s been available in the past has been the polygraph—a cobbled-together battery of sensors that monitor the subject’s pulse, sweating, and breathing rate. Polygraph testing is error prone, and experts struggle even to quantify its level of reliability.
One reason for that struggle is that the interpretation of a polygraph’s measurements is unavoidably subjective. Set the detection threshold low enough and you’ll net almost any liar. But you’ll also falsely identify many truth tellers. Laboratory studies of polygraph testing show that when you set the threshold so that the false positive rate is a troublingly high 30 percent, you’ll still detect lies only between 64 and 100 percent of the time. That’s a wide range, and the low end reflects rather poor performance for a lie detector. Also, experts generally agree that polygraph testing probably works worse in the real world than it does in the lab, though how much worse isn’t clear.
For these reasons, the U.S. National Academy of Sciences was somewhat vague in its overall assessment of polygraphs, saying that these machines could (at best) discriminate lies from the truth at rates “well above chance, though well below perfection” and remain “an unacceptable choice for security screening.” No wonder the U.S. legal system has never fully embraced this technology. In most other parts of the world, the courts, law enforcement, and even the business community just scoff at it.
So now we have a new breed of lie detector, based on MRI, that promises to do away with using unreliable physiological responses to reveal a person’s innermost thoughts. With the help of multimillion-dollar scanners, sophisticated pattern-matching algorithms, and cutting-edge neuroscience, you can now detect the hardwired patterns in the brain that indicate deception—or at least that’s what supporters claim. I was determined to find out for myself whether this was true, even if I had to ’fess up to some personal foibles to do it.