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[August 16, 2002]

Points Of Presence

By Laura Guevin
Editorial Director,

Picking Your Brain In The Name Of Security

While doing some in-depth research on biometric technologies recently, I came across a subject I hadn't encountered before: brain fingerprinting. At least I don't recall coming across it before -- perhaps a scan of my brain would prove otherwise. The technology isn't a new concept, nor does it rely on biometric traits, although it can best be used in tandem with biometrics -- surprisingly -- to protect the privacy of those being tested.

Brain fingerprinting was invented more than 10 years ago, when the CIA invested some money in a psychologist, Emanuel Donchin, and his student, Lawrence Farwell. The theory was to find out what they could do to expand on a standard EEG test, which uses super-sensitive electrodes to measure fluctuations in electrical potential caused by patterns of brain activity. Donchin specialized in a characteristic bump in the EEG scan called the P300, which occurs approximately a third of a second after the subject being tested recognizes something significant.

Farwell continued testing the viability of using P300 for criminal cases, and ended up patenting the Farwell Brain Fingerprinting method. The system basically works by flashing words or pictures relevant to a crime on a computer screen, along with irrelevant words and pictures. Electrical brain responses are measured through a patented headband equipped with sensors. Farwell discovered that a memory and encoding related multifaceted electroencephalographic response (MERMER) was elicited when the brain processed noteworthy information it recognized. Therefore, if details of a crime only a perpetrator would know about were presented, a MERMER would be emitted by the brain of the perpetrator -- but not by the brain of an innocent suspect.

In Farwell's Brain Fingerprinting, a computer analyzes brain responses to detect the MERMER, and determines whether or not the crime-relevant information is stored in the brain of the suspect. This is also known as Computerized Knowledge Assessment. One of the strongest arguments for this type of testing is that human judgment doesn't enter the picture -- the results are scientific. Whereas other forms of questioning, like interrogation, involve intimidation and verbal "persuasion," no verbal communication is required with brain fingerprinting. And whereas lie detector tests have been known to fail, especially among skilled liars who have learned how to skew results by clenching their teeth, etc., the impulses of the brain supposedly cannot be manipulated for the purposes of this test.

Of course, there's a laundry list of reasons why this method is not foolproof. The first that comes to mind is that the crime-relevant questions and pictures are chosen by humans, and are therefore subjective. What if an innocent subject is shown an image of the crime scene -- a place he or she has been to before, but not necessarily at the time of the crime? What if certain details of the crime match up with someone's similar experiences, and therefore recognition is registered?

Farwell contends that his method has proven 100-percent accurate in tests conducted on FBI agents, as well as in tests for a U.S. intelligence agency and the U.S. Navy. It aided Missouri prosecutors in convicting a serial killer in 1998, 14 years after the rape and murder of Julie Helton. After J.B. Grinder underwent brain fingerprinting, in which he responded positively to certain details of the crime, he confessed to Helton's murder and was sentenced to life in prison. He subsequently confessed to other murders of young women. Farwell also presented test results to a court in Iowa in an attempt to exonerate a man that had been convicted of a murder 22 years earlier, and who had claimed innocence. Farwell said the test results showed, with 99.99 percent accuracy, that Terry Harrington had not committed the crime. The test results prompted the only witness to the crime to recant his testimony against Harrington in a sworn testimony, admitting it was a fabrication. Yet the judge in the trial rejected the new evidence in a 2001 ruling, claiming it was unlikely to change the result of a trial. Harrington is appealing the ruling.

Farwell is a strong proponent of using brain fingerprinting to screen airline passengers, and as an added security measure at various screening checkpoints. The theory is that people could be screened without revealing their names, through the use of biometrics. For instance, at the same time the brain wave test was given, biometric data like fingerprint or iris scan would be gathered to link the person being tested to their physical profile. The biometric profile would only need to be updated once every few years. The person being tested would then put on a headset and watch video images on a standard computer monitor for 10 minutes. The test would be used to present data and information terrorists are familiar with.

Since the brain fingerprinting would be completely automated, it would not be subject to human interpretation, and therefore would be unbiased to race, creed, color, sex, religion, and other individual characteristics. The computerized security risk factor profile generated by the brain fingerprinting would be linked to a person's biometric data, but not necessarily to the person's name.

The very idea of brain fingerprinting conjures up images of a Big Brother-like world in which knowing too much could be dangerous, and the wrong response to an image could get you convicted of a crime you may or may not have committed. Then again, if the technology is used correctly and unobtrusively, perhaps it could be beneficial for screening out terrorists or other threatening characters.

The one major flaw I see in it, however, is the contention that it is 100 percent automated, and therefore scientifically sound. The very nature of the questioning that fuels the MERMER is subjective. Just as the very nature of the information collected from a crime scene is fueled by human input. Of course, there are standards and procedures for collecting such information, just as I'm sure there will be standards for questioning and video presentation if brain fingerprinting is ever widely implemented by law enforcement. I just hope those adopting this technology proceed with caution, as there is obviously a huge potential for abuse and error.

Laura Guevin is the editorial director of BiometriTech, an online magazine and newsletter covering biometric technologies and products. She welcomes your comments at

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