fMRI and Counterterrorism
March 20, 2008
Bioethicists have for years been debating the conscientiousness of using neuroimaging techniques outside of a clinical setting, such as in courtroom situations or interrogations. These discussions are inevitable, as an fMRI visualization of brain activity seems—at least potentially—to be a much more precise indicator of hidden thoughts and emotions than the standard polygraph. Jonathan Marks, an associate professor of bioethics at Penn State recently drew attention to this debate by asserting that fMRI is being used by the United States government in the interrogation of terrorist suspects.
fMRI is a neuroimaging technique that was developed in the 1990s and has since become the preferred method of imaging brain activity. It involves placing the head of the subject in a donut-shaped magnetic device, which can detect subtle changes in electromagnetic fields. When an area of the brain is in use, blood flow is directed to that region. Hemoglobin, an oxygen-transporting protein in red blood cells, exhibits different magnetic properties when oxygenated as compared to when it is deoxygenated. This is how the fMRI detects the flow of oxygenated blood and, based on the resultant magnetic field, produces an image of which areas of the brain are being used. fMRI has been used to help us gain a better understanding of which brain regions are active during a number of different states, such as happiness, sadness, fear, and anger.
Marks, however, points out that fMRI technology is not reliable enough to be used as a lie detector, and warns our government using it could lead to further abuse of prisoners and human rights violations. He claims that the U.S. is using fMRI not only as a lie detector, but also to single out terror suspects for aggressive interrogation if it indicates they recognize certain names or stimuli (e.g. the name of a terrorist sect leader). Marks bases this allegation on previously unpublished statements made by a U.S. interrogator.
While fMRI may have the potential to one day be an accurate lie detector, most experts in the imaging field would agree that right now it isn’t reliable enough to be used outside of a clinical or laboratory setting. There are a number of reasons for this. One is that, although fMRI images currently have the best resolution neuroimaging can offer, those images don’t provide a complete view of the intricacies of brain activity. They are made up of pieces known as “volume picture elements”, or voxels. The smallest voxels an fMRI can make out are about the size of a grain of rice, and would include the activity of tens of thousands of neurons. While this is helpful in determining the stimulation of brain regions, it is not precise enough to break that activity down into the interaction of very small groups of neurons. Thus, it is far from providing a complete image of neuronal activity—at least far enough to make it an ethically questionable method to use to condemn or exculpate those whose brains are scanned by it.
More important, especially in the use of fMRI with terror suspects, is the fact that fMRI data is drawn from averages of groups of people in laboratory settings. Individual differences in brain activity could be significant, and could be even more drastic across cultures. Additionally, a subject’s baseline fMRI measurements could change over time or by setting. Marks suggests it could take up to weeks of testing to determine what any one person’s baseline neural activity is. Also, a subject who is undergoing the stress of being held by a hostile party may exhibit brain activity that is already much different than that obtained from a participant in a laboratory experiment.
This is not to say fMRI might not be able to one day be used as a lie detector. A group of researchers from the University of Pennsylvania conducted an fMRI study in 2002 to determine which areas of the brain were active while participants gave deceptive responses to questions. The results indicated that the anterior cingulate cortex and superior frontal gyrus were specifically associated with lying, causing the researchers to conclude there are specific neural correlates to deception that are recognizable by fMRI. Even the lead author of that study, however, cautions that fMRI technology is not at the point where it could be used to identify a liar with certainty. He points out that the slightest changes in the wording of a question could produce different neural responses.
Marks’ fear is that fMRI will be used to screen suspected terrorists, resulting in their subjection to aggressive interrogation techniques. These types of techniques can cause a suspect to admit to crimes he/she had no part in, just to end the torture. Thus, Marks’ asserts, the fMRI won’t aid in finding out the truth, it will just allow interrogators to feel more justified in using whatever tactic they feel necessary to extract the information they are looking for. He cites President Bush’s veto of legislation this month that would have banned aggressive interrogation by the CIA an indication this misuse of fMRI could go on unchecked.
fMRI is an amazing technology, and its value will probably continue to be reinforced over the next several decades (or until it is displaced by an even more precise method). But its current limitations in determining whether someone is lying or not are clear. It’s depressing to think that, while neuroimaging has led to better medical care and a significantly improved understanding of the brain, it may also have led to the torture of individuals, some who may have been erroneously singled out due to a misunderstanding (or disregard) of the limits of the technology.