Functional Magnetic Resonance Images and Lie Detection

James W. Evans, Jr., J.D., LL.M. Candidate

The ability to distinguish truth from lie, through the use of new technologies, has been a challenge for scientists for decades.  Political, business and legal organizations are all showing a keen interest in this technology.  Scientists have yet to develop a device that consistently shows deception.  Current events in neuroimaging, however, may have changed traditional notions of lie detection and provided greater understanding of how the brain distinguishes a lie from the truth.

Until now, the polygraph has been the only readily available lie detection devise in use.   Law enforcement and business security officials have used polygraphs for decades to screen employees and to solicit damaging statements from witnesses and potential defendants.  Polygraph results are rarely accepted in the courtroom.  In fact, only New Mexico allows polygraph results to be admissible as evidence in court without prior agreement of both sides.1

The polygraph measures fluctuations in several secondary signs of nervousness, including the rate and depth of breathing, perspiration, blood pressure and pulse, all under the assumption that when people lie, they become nervous.  Judges have excluded polygraph results from the courtroom for that very reason – the accuracy of polygraph results is questionable when the subject is nervous, angry or agitated.  A polygraph machine cannot read minds.  In a recent study conducted by Daniel Langleben, M.D. at the University of Pennsylvania School of Medicine proved that machines could in deed read minds.2

The group used a Function Magnetic Resonance machine (fMRI) to study deception.  An fMRI is a neuroimaging devise, which employs strong magnetic fields to induce molecules within the brain tissue to emit radio signals.  By mapping the signals onto digital images of the brain, the fMRI is able to monitor the movement of blood, determining which areas of the brain are activated by a particular task.3   Dr. Langleben and his colleagues undertook a study to determine whether patterns of increased brain activity could be detected when volunteers lied compared with when they told the truth.

 Volunteers were given a sealed envelope containing a playing card and a twenty-dollar bill.  They were asked to not disclose the card.  The volunteers were then told to deny having the card during a computerized interrogation, and that if they could fool the computer, then they could keep the money.  When people gave truthful answers, the fMRI showed increased activity in parts of the brain related to vision and finger movement.  When they lied, the same areas lit up, but so did additional areas including the anterior cingulated cortex, a section of the brain that has been linked to monitoring of errors and attention.  Dr. Langleben concluded that the study showed “a neurophysiological difference between deception and truth at the brain activation level that can be detected with an fMRI.”  Essentially, it took more mental energy to lie than to tell the truth.

 At the conclusion of the study, Dr. Langleben conceded that the study had a number of limitations and further testing would need to be conducted to corroborate the pattern predictive of truth telling and deception.  Other potential problems with the technology include the following:  fMRI machines are bulky, expensive and highly sensitive to motion, all factors decreasing the likelihood of its real-world application.  But for people who are willing to spend the money, the admission of fMRI results into a courtroom may not be far away.

 Although the field of brain imaging is relatively new, the admission of neuroimages in court for the purposes of making inferences about behavior has been taking place for the past ten twenty years to prove the dangerousness, sanity, and cognitive impairment of litigants, usually criminal defendants, at trial.  For example:

These cases and others have been highly contested by prosecutors who have argued that the inferences made by these psychiatrists were not reliable.  Though it would appear that Daubert would provide the necessary prescreening function to exclude unreliable evidence and “junk science,” neuroimages have proven to be extremely powerful to both judges and juries alike.  Apparently, the images provide a “hard science” validation to traditional “soft science” expert psychiatric opinion.

Nevertheless, in the near future, we may not only discover whether a person is being deceptive, but we could determine whether the deception was an on-the-sport fib or a premeditated lie.   We will also be able to determine peoples deeply held contentions and beliefs.  With advances in neurotechnology occurring at such a rapid pace, our legal system will soon be overwhelmed with new types of evidence that our current system has not been able to effectively handle.  In fact, this new evidence may even alter our system of justice.

1.  State v. Gonzales, 11 P.3d 131 (N.M. 2000)
2.  Langleben, D.D., Schroeder, L, Maldjian, J.A., Gur, R.C., McDonald, S., Ragland, J.D., O’Brien, C.P. and Childress, A.R., 2001.  RAPID COMMUNICATION, Brain Activity during Simulated Deception:  An Event-Related Functional Magnetic Resonance Study, NeuroImage, May 2001.
3.  Functional magnetic resonance imaging (fMRI):  A “window into the brain”, by A. Parry and P.M. Matthews.
4.  U.S. v. Hinckley, 725 F.Supp. 616 (U.S. Dist. Ct., D.C. 1989)
5.  People v. Weinstein, 591 N.Y.S.2d 715 (Sup. Ct. 1992)