Brain fingerprinting

It sounds like science fiction: strap a few electrodes onto someone’s head and determine whether his or her brain contains certain information. But in fact “brain fingerprinting” is here today.

Brain fingerprinting is based on the “ah-ha” response, an involuntary response by the brain to information it has been exposed to before. Dr. Lawrence Farwell, the Harvard-trained physician who has developed brain fingerprinting, says this response can be clearly recognized through the use of an electroencephalogram, which shows the brain’s electrical activity over time.

Dr. Farwell calls this measurable response a “memory- and encoding-related multifaceted electroencephalographic response,” or MERMER. At the core of the MERMER is a brain wave called a P300 which scientists have long known is the result of increased activity by neurons subjected to a rare but meaningful stimulus. One way to generate a P300 wave, for example, is to present a subject with a long list of random names with the subject’s own name mixed in with them. As early as 1988, a study showed that the P300 response could be used to identify college students trying to conceal the fact that they had stolen something–but only with about 87.5 percent accuracy.

The MERMER, however, includes both the P300 and an electrically negative response that occurs after the P300, and Dr. Farwell says his tests using it have produced no false negatives or positives. In one of the early tests (which were funded by the CIA and FBI), Dr. Farwell was able to correctly pick out all of the FBI agents in a group of people by measuring their brain activity while exposing them to words and phrases flashed on a computer screen, some of which would only be meaningful to agents.

Subjects in a brain fingerprinting test are exposed to three different kinds of information: targets (information the subject definitely knows); irrelevants (information the subject definitely does now know) and probes (information relevant to the crime or situation, which the subject may or may not know). Target information produces a MERMER, which serves as a control. Irrelevant information will not produce a MERMER. A probe may or may not produce a MERMER; if it does, then that information is already in the subject’s brain.

In a criminal case, the subject would be shown words, pictures or sounds relative to the crime that aren’t public knowledge: information, in other words, that only the criminal would have. The test would show if that information was present in the suspect’s mind; if it wasn’t, he couldn’t have committed the crime. If it was, it would be strong evidence of his guilt.

In 1998, when Dr. Farwell conducted a brain fingerprinting test in Missouri on J.B. Grinder, who had been a murder suspect for 15 years. The test showed that he had specific information about the crime scene stored in his brain. Grinder pleaded guilty in exchange for a life sentence without parole, and confessed to the previously unsolved murders of three other women.

In 2000, Dr. Farwell conducted a test on Terry Harrington, convicted of murder in Iowa in 1978 and serving a life sentence. The test showed that the information stored in Harrington’s brain did not match the crime scene, but did match his alibi. Last year the Iowa Supreme Court reversed Harrington’s conviction and ordered a new trial, which the State decided not to proceed with. Today Harrington is a free man. During the appeal process, brain fingerprinting evidence was ruled admissible in court.

The U.S. Supreme Court is currently weighing the appeal of Jimmy Ray Slaughter, currently on Oklahoma’s death row for a double murder. His appeal is based in part on Dr. Farwell’s brain fingerprinting test, which showed that Slaughter’s brain did not contain certain information about the crime scene.

Unlike standard lie detecting machines, or polygraphs, which have been widely criticized as inaccurate, brain fingerprinting does not rely on an emotional response. No matter how cool a liar a subject may be, he cannot control the involuntary MERMER response to a familiar word, picture or object. Brain fingerprinting, if it proves out, therefore holds the potential to greatly increase the likelihood of convicting criminals and reduce the risk of wrongful convictions.

Brain fingerprinting can also help doctors measure memory and cognitive function, providing a diagnostic test for Alzheimer’s and other neurological diseases, and a means of testing the effectiveness of treatment.

The widespread use of fingerprinting revolutionized criminal investigations at the beginning of the 20th century. Brain fingerprinting could do the same at the beginning of the 21st.

Permanent link to this article: https://edwardwillett.com/2004/03/brain-fingerprinting-2/

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