FMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process (FMRIB Center).
This is how it works: oxygen is delivered to neurons by haemoglobin in capillary red blood cells. When neuronal activity increases there is an increased demand for oxygen and the local response is an increase in blood flow to regions of increased neural activity.
Haemoglobin is diamagnetic when oxygenated but paramagnetic when deoxygenated. This difference in magnetic properties leads to small differences in the MR signal of blood depending on the degree of oxygenation.
Since blood oxygenation varies according to the levels of neural activity these differences can be used to detect brain activity. This form of MRI is known as blood oxygenation level dependent (BOLD) imaging (id).
It is claimed that through this process, FMRI can be used as a lie detector test. The question now arises that should the FMRI be used as a lie detector test, will the results be admissible in evidence in our courts of law in light of the Daubert ruling? This paper will try to answer this question by testing FMRI against the four questions set up by the Supreme Court in the said decision.
Is FMRI a Testable Technique?
The Supreme Court, in discussing how evidence should pass this test, the judge must ascertain whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue.
A key question to be answered in determining whether a theory or technique is scientific knowledge that will assist the trier of fact will be whether it can be(and has been) tested (92-102). The main concern of the Supreme Court here is the reliability of the technique and reduction of falsifiability.
FMRI is one of the most recently developed forms of neuroimaging but the idea underpinning the technique - inferring brain activity by measuring changes in blood flow - is not new (FMRIB Center). The technique, however, is relatively new.
FMRI still has not gained acceptance as a reliable method of lie detection to replace the polygraph. Recent studies only indicate that FMRI may be more reliable than the polygraph but FMRI is yet to attain its full potential.
Dr. Faro, in studying FMRI admits that because the polygraph test, while improved over the last 10 to 15 years, is not as accurate as it needs to be, a better method for detecting deception clearly needs to be developed (Orenstein 30).
He add that he is convinced that FMRI used with or without polygraph will someday be the new gold standard (id). The scientists remain hopeful the FMRI will someday be the standard. But as of today, its acceptability as a lie detection test is still on a thin balance. In short, FMRI has not yet been fully tested so as to be acceptable as a lie detection method.
Despite this, it is noteworthy that FMRI lie detection centers have already been set up in the United States. They are No Lie MRI, Incorporated and Cephos Corporation. This shows that FMRI is gaining ground as a stand alone test for lie detection and not just merely as a supplement to the polygraph.
Has FMRI Been Peer Reviewed?
The concern of the Supreme Court in including this test is to make sure that the theory or technique has been subjected to scrutiny by the science community because it is only then that the substantive flaws of the methodology can be revealed.
Without effort, FMRI will pass this test. FMRI has been subjected to tests and retests by a lot of scientists to verify its efficiency and effectiveness. In fact the University of Oxford established its own FMRIB Center to study it as a field of discipline.
As mentioned earlier, Dr. Faro already tested whether it can replace the polygraph or not. And lastly, there are also plenty of studies on FMRI being conducted as of this moment because it has inspired general interest in the science community. The abstracts of these studies can be viewed in the internet.
Does FMRI have a Known Error Rate or Standard Controlling it Operation?
The error rate of FMRI has not yet been established because as mentioned earlier, it is a recent development in nueroimaging and still has not been tested thoroughly. However, Dr. Faro says that subjects would have to lie perfectly for them to beat the FMRI (Orenstein, id).
He says that FMRI would be much harder to beat than polygraph because it measures a primary cognitive response that begins within the deep structures of the brain. Lying involves coordinating complex activations in many different parts of the brain that relate to awareness, understanding, inhibition, and emotion.
One way of arguing the admissibility of the FMRI according to this test is to argue how polygraphs are admissible in courts. According to the American Polygraph Association, polygraph results are admissible in some federal circuits and states (Orenstein, id).
And this is so even though the polygraph is only 85% to 90% accurate when the subjects are being deceptive and only 70% to 75% accurate when subjects are being truthful. If polygraphs are admissible in court, then FMRI should also be admissible considering that the latter is more accurate than the former.
However, there is a great cloud over the admissibility of the FMRI when the procedure of conducting it is considered. Subjects participating in a fMRI experiment are asked to lie still and are usually restrained with soft pads to prevent small motions from disturbing measurements.
It is possible to correct for some amount of head movement with post-processing of the data, but large transient motion can render these attempts futile. Generally motion in excess of 3 millimeters will result in unusable data.
Thus, a very accurate data is hard to obtain from FMRI. A movement of only 3 millimeters will already render the data useless. Considering that the shortest time needed to conduct an FMRI is 15 minutes, it is easy to conclude that an FMRI is hardly accurate.
Of course, this can be addressed by utilizing mechanisms to reduce movements. And the FMRI centers should have already addressed this problem. But standing as it is, this fact casts doubt on the admissibility of FMRI because of the possible large inaccurcies of the data gathered during testing.
There is also a concern on the reliability of the FMRI with regard to complex lies. Complex lies are half truths and sometimes rhetorical answers to the standard questions asked during an FMRI session. They are answers which have shades of truth or just an answer with a misperception about a question. This area of FMRI still has not been studied thoroughly making it less reliable as a method of lie detection.
Is the Underlying Science Generally Accepted?
Yes, the underlying science behind FMRI is generally accepted. As mentioned earlier, the idea underpinning the technique (FMRI) - inferring brain activity by measuring changes in blood flow - is not new. The study of FMRI draws from physics, psychology, neuroanatomy, statistics and electrophysiology, all of which are generally accepted fields of discipline. Thus, under this test, FMRI is admissible in evidence.
In conclusion, FMRI is not admissible in evidence when tested against the Daubert standards. First of all, it still has not been thoroughly tested as a science. The method of conducting has not yet been perfected by the testing centers. These two factors accounts for somewhat doubtful results and may seem not convincing before the eyes of the courts.
In fact, criticisms as to the accuracy of the data gathered during FMRI have always been the the biggest factors in sustaining its non-acceptability. Issues raised such as there are non-neural influences in the change of magnetic fields in the blood vessels have been raised and these have not been specifically addressed by the current studies on FMRI.
It has also been raised that FMRI only measures the secondary physiological correlates of neural activity, it is not a direct measure. This means it is not a truly quantitative measure of mental activity - when comparing the FMRI response between individuals it is impossible to say whether the differences are neural or physiological in origin (FMRIB Center).
These are the scientific arguments against the FMRI. Of course, there are also ethical arguments against its use but they will not be discussed in this paper for being irrelevant.
One argument which, to the mind of this reader, will really cause the courts to strike down FMRI evidence as inadmissible is the constitutional argument that it violates the right to privacy. During an FMRI session, collateral information about the subject may be obtained but which he would have wanted to keep secret. This is a violation of the right to privacy.
Of course, it is already established that such a mechanical method of subjecting one's self to physical examination is not violative of the right against self-incrimination. However, this is not the case I am pointing out. What if some information not related to the trial or to the case has been obtained during the FMRI session?
True that it will not be offered in evidence but the damage of violating the right to privacy has already been incurred. What will the subject do then? If the FMRI violates the constitutional right to privacy, then anything obtained during such sessions, though irrelevant and immaterial to the case, should be kept confidential and inadmissible in evidence in all courts and tribunals.
Secondly, the FMRI should be inadmissible in evidence because its error rate still has not been determined to a certain definitive degree. It matters not if polygraph evidence is admissible in many federal and state courts. As of the moment, the Supreme Court still has no definitive ruling as to its admissibility (Orenstein).
Moreover, the accuracy of the data obtained during FMRI sessions is still in doubt when the procedure is considered. The fact that a 3-millimeter movement will render the data untruthful is enough for the courts to cast a doubtful eye on FMRI evidence. As to the matter of complex lies, this provides the subjects a way to beat the FMRI.
They even do not have to lie. They can just answer half-truths or even use rhetorical answers and they could already beat the FMRI.
All these point to rejection of FMRI evidence considering the attitude of the courts toward the Daubert principle. In fact, litigants say that courts are more strict than what the Supreme Court suggested in the Daubert case (Hileman 2003).
However, as a statement of hope for FMRI, today is not the timely moment to test its admissibility in our courts of law. It should be given more time to develop into a better-founded discipline and its loopholes tied end-to-end. Then perhaps someday, our society will find it a very reliable method in lie detection and the results be admissible in evidence in our courts of law.
Introduction to FMRI. FMRIB Center, University of Oxford. December 4, 2007. http://www.fmrib.ox.ac.uk/education/fmri/introduction-to-fmri/introduction/
Orenstein, Beth. Guilty? Investigating FMRI's Future as a Lie Detector. May 16, 2005. Radiology Today. Vol 6 No. 10 p. 30.
Supreme Court of the United State. Daubert vs Merrell Dow Pharmaceuticals. June 28, 1993. retrieved December 4, 2007. http://straylight.law.cornell.edu/supct/html/92-102.ZO.html
Weiller C et al (2006). "Clinical potential of brain mapping using MRI". Journal of Magnetic Resonance Imaging 23 (6): 840–850
Scott A. Huettel, Allen W. Song, Gregory McCarthy, Functional Magnetic Resonance Imaging, Sinauer Associates, 2004.
Hileman, Bette. Daubert Rules Challenge Courts. July 7, 2003. Our Stolen Future. Retrieved December 4, 2007. http://www.ourstolenfuture.org/press/2003/2003-0707-CEN-daubert.htm
Silberman, Steve. Don't Even Think About Lying. Wired Magazine. Retrieved December 4, 2007. http://www.wired.com/wired/archive/14.01/lying_pr.html