By Lyndon Lewis, Neuroscience Student at Washington State University
From http://www.rocklin.k12.ca.us/staff/lbrun/chemweb/Forensics/Links.htm
If you could have any one super power what would it be? Most people might choose superhuman strength, time travel, telepathy, being invincible or even immortality. If you chose telepathy however, you might regret your choice. As time progresses, neuroscientists are making significant advances in being able to “read” people’s minds. Yes, it sounds crazy or perhaps like an idea from a sci-fi movie but in fact, it is the reality.
Although the ability to “read” people’s minds is becoming less of a fantasy, the matter under scrutiny is the accuracy of mind “reading” tests and if they are reasonable to use in the courtroom. Before I present the facts and throw my opinion into the mix, I will provide you with an overview of the main tests under consideration for increased courtroom use.
P300-MERMER- uses electrical brain responses to detect if a subject has knowledge of an event. This test works first by being calibrated to an individual’s specific brain response to targets and irrelevant stimuli. Targets (information that the experimenter knows the subject knows) are presented and the subject’s brain responses are recorded. Irrelevants (information the experimenter knows the subject has no knowledge of) are presented with the targets and brain responses are recorded. After this calibration is complete, probes (information that only the criminal would know) are presented to the subjects and if probe responses align with the target responses, the subject is considered to have knowledge of the crime.
CT scans- use an x-ray photon that passes through the brain. It detects atrophy, lesions, hemorrhages and other abnormalities that can be used to argue that somebody has been assaulted.
MRIs- use electromagnetic radiation and magnetic fields to show the structure of the brain. It is similar to a CT scan but has enhanced visual quality that can show smaller lesions. MRIs in the courtroom are often used to show that somebody has an abnormal brain which could have caused them to exhibit abnormal behavior.
fMRIs- use blood flow/oxygenation in the brain to detect areas of activity. Scientists have found that the parieto-frontal areas are more active in the process of lying. With such knowledge, we can use fMRIs to measure the blood flow in these areas and have a good chance of knowing if somebody is telling a lie based on the activity.
Companies such as No Lie MRI claim that their fMRI lie detection studies are 90% accurate. Another study performed by Farwell and Donchin used the P300- MERMER on 20 knowledgeable subjects and 20 non-knowledgeable subjects and found the test to be 87.5% accurate. When compared to the polygraph test which is accurate 70% of the time, which would you rather have in your courtroom if you were the judge?
The major question we need to ask ourselves is: are these tests more or less accurate than the systems we already use in the courtroom? According to Elena Rusconi who works at the Department of Security and Crime Scene at University College London, “studies show that the vast majority of onlookers correctly distinguish truth from lies when told by a stranger only about 54% of the time.” That is almost as bad as chance. Therefore, if we can confidently say that tests such as the P300-MERMER or the fMRI offer higher accuracy than eye witnesses and tests being used already, such as the polygraph, I don’t see a problem in replacing older less accurate techniques with newer ones.
With that being said, it would not be right to convict someone over one small piece of evidence or one neuroimaging test no matter what level of accuracy it holds. I am not suggesting that we uproot our system altogether but if the courtroom uses neuroscience responsibly as a piece to the puzzle rather than a ticket to condemn, I believe the justice system is moving in the right direction because 54% is not cutting it.