- Published: November 30, 1999
In recent years, scientists, start-up companies, and the mass media alike have become increasingly interested in applying fMRIs to lie detection. The technology is based on the fact that lying and telling the truth employ different neural circuitries, which fMRIs, in taking real-time readings of blood flow in the brain, can differentiate between. Start-up companies such as Cephos and No Lie MRI have touted the fMRI as this generation’s polygraph.
While ethical, practical, and judicial concerns about fMRI lie detection abound, so do questions about just how fool-proof the system is, and what limits fMRI technology faces. Can the machine, for instance, distinguish between an unintentional misstatement of fact and a deliberate lie? A study published in October of 2008 in the Journal of Brain and Cognition investigated this question by using a word recognition paradigm. Subjects memorized lists of words, and later had to identify words flashed on the screen as previously memorized or not. In one situation, the subjects completed the latter part to their best efforts. In the second, the subjects were instructed to deliberately lie about what words they had or had not seen before. Interestingly, the researchers found that intentional lying involved significant prefrontal cortex activation, where as unintentional mistakes did not. Thus, the researchers concluded that the fMRI can indeed distinguish between errors of memory and intentional faked responses.
This is a promising progress in validating the use of fMRIs as lie detectors, other concerns remain. I wonder, for instance, if an fMRI could distinguish between a factual statement versus a statement which the subject believes to be true, but which is actually false. For instance, let’s say an eye witness is convinced she saw an Asian man, when in reality the man was white. While the eye witnesses’ statement is in reality factually inaccurate, she nonetheless believes her story is true. fMRI technology would likely support her as telling the truth, although her information is factually incorrect. So what do we do?