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   Illuminating lies with brain scan outshines polygraph test   
      
   fMRI spots more lies in first controlled comparison of the two technologies   
   Date:   
   November 3, 2016   
   Source:   
   University of Pennsylvania School of Medicine   
   Summary:   
   When it comes to lying, our brains are much more likely to give us away than   
   sweaty palms or spikes in heart rate, new evidence suggests. The study found   
   that scanning people's brains with fMRI, or functional magnetic resonance   
   imaging, was significantly    
   more effective at spotting lies than a traditional polygraph test.   
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   Magnetic resonance imaging of the brain (stock image).   
   Credit: © Maxim Pavlov / Fotolia   
   When it comes to lying, our brains are much more likely to give us away than   
   sweaty palms or spikes in heart rate, new evidence from researchers in the   
   Perelman School of Medicine at the University of Pennsylvania suggests. The   
   study, published in the    
   Journal of Clinical Psychiatry, found that scanning people's brains with fMRI,   
   or functional magnetic resonance imaging, was significantly more effective at   
   spotting lies than a traditional polygraph test.   
      
      
   It has been demonstrated that when someone is lying, areas of the brain linked   
   to decision-making are activated, which lights up on an fMRI scan for experts   
   to see. While laboratory studies showed fMRI's ability to detect deception   
   with up to 90 percent    
   accuracy, estimates of polygraphs' accuracy ranged wildly, between chance and   
   100 percent, depending on the study. The Penn study was the first to compare   
   the two modalities in the same individuals in a blinded and prospective   
   fashion. The approach adds    
   scientific data to the long-standing debate about this technology and builds   
   the case for more studies investigating its potential real-life applications,   
   such as evidence in the criminal legal proceedings.   
      
   Researchers from Penn's departments of Psychiatry and Biostatistics and   
   Epidemiology found that neuroscience experts without prior experience in lie   
   detection, using fMRI data, were 24 percent more likely to detect deception   
   than professional polygraph    
   examiners reviewing polygraph recordings. In both fMRI and polygraph,   
   participants took a standardized "concealed information" test.   
      
   Polygraph, the only physiological lie detector in worldwide use since it was   
   introduced in its present form more than 50 years ago, monitors individuals'   
   electrical skin conductivity, heart rate, and respiration during a series of   
   questions. Polygraph is    
   based on the assumption that incidents of lying are marked by upward or   
   downward spikes in these measurements. Despite having been deemed inadmissible   
   as legal evidence in most jurisdictions in the United States or for   
   pre-employment screening in the    
   private sector for almost 30 years, polygraph is widely used for government   
   background checks and security clearances.   
      
   "Polygraph measures reflect complex activity of the peripheral nervous system   
   that is reduced to only a few parameters, while fMRI is looking at thousands   
   of brain clusters with higher resolution in both space and time. While neither   
   type of activity is    
   unique to lying, we expected brain activity to be a more specific marker, and   
   this is what I believe we found," said the study's lead author, Daniel D.   
   Langleben, MD, a professor of Psychiatry.   
      
   To compare the two technologies, 28 participants were given the so-called   
   "Concealed Information Test" (CIT). CIT is designed to determine whether a   
   person has specific knowledge by asking carefully constructed questions, some   
   of which have known answers,   
    and looking for responses that are accompanied by spikes in physiological   
   activity. Sometimes referred to as the Guilty Knowledge Test, CIT has been   
   developed and used by polygraph examiners to demonstrate the effectiveness of   
   their methods to subjects    
   prior to the actual polygraph examination.   
      
   In the Penn study, a polygraph examiner asked participants to secretly write   
   down a number between three and eight. Next, each person was administered the   
   CIT while either hooked to a polygraph or lying inside an MRI scanner. Each of   
   the participants had    
   both tests, in a different order, a few hours apart. During both sessions,   
   they were instructed to answer "no" to questions about all the numbers, making   
   one of the six answers a lie. The results were then evaluated by three   
   polygraph and three    
   neuroimaging experts separately and then compared to determine which   
   technology was better at detecting the fib.   
      
   In one example in the paper, fMRI clearly shows increased brain activity when   
   a participant, who picked the number seven, is asked if that is their number.   
   Experts who studied the polygraph counterpart incorrectly identified the   
   number six as the lie.    
   The polygraph associated with the number six shows high peaks after the   
   participant is asked the same questions several times in a row, suggesting   
   that answer was a lie. The scenario was reversed in another example, as   
   neither fMRI nor polygraph experts    
   were perfect, which is demonstrated in the paper. However, overall, fMRI   
   experts were 24 percent more likely to detect the lie in any given participant.   
      
   Beyond the accuracy comparison, authors made another important observation. In   
   the 17 cases when polygraph and fMRI agreed on what the concealed number was,   
   they were 100 percent correct. Such high precision of positive determinations   
   could be especially    
   important in the United States and British criminal proceedings, where   
   avoiding false convictions takes absolute precedence over catching the guilty,   
   the authors said. They cautioned that while this does suggest that the two   
   modalities may be    
   complementary if used in sequence, their study was not designed to test   
   combined use of both modalities and their unexpected observation needs to be   
   confirmed experimentally before any practical conclusions could be made.   
      
   "While the jury remains out on whether fMRI will ever become a forensic tool,   
   these data certainly justify further investigation of its potential,"   
   Langleben said.   
      
      
   Story Source:   
      
   Materials provided by University of Pennsylvania School of Medicine. Note:   
   Content may be edited for style and length.   
      
   Journal Reference:   
      
   Daniel D. Langleben, Jonathan G. Hakun, David Seelig, An-Li Wang, Kosha   
   Ruparel, Warren B. Bilker, Ruben C. Gur. Polygraphy and Functional Magnetic   
   Resonance Imaging in Lie Detection. The Journal of Clinical Psychiatry, 2016;   
   1372 DOI: 10.4088/JCP.   
   15m09785   
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