Not Guilty. "The Brain Never Lies."

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Not Guilty. "The Brain Never Lies."

Newspaper article

By: Anne McIlroy

Date: November 5, 2005

Source: McIlroy, Anne, "Not Guilty. 'The Brain Never Lies.'" Toronto Globe and Mail (Saturday, November 5, 2005) F6.

About the Author: Anne McIlroy is the science reporter for the Toronto Globe and Mail, Canada's leading daily newspaper, founded in the 1840s, with a circulation of over one million.


The search for truth is as old as civilization itself. The basis of modern "lie detection" is the polygraph, which measures the emotional and physiological changes that occur when most people tell a lie. In medieval times, however, little was understood about how the body and brain work, and courts of that era believed divine intervention would indicate if a suspect was, or was not, telling the truth. It was believed that God would protect an innocent and truthful person from coming to harm in any "test" of their veracity. So, for instance, the suspect would have to carry a red hot iron bar or walk over hot coals. If they were burned, it was proof they were lying and they could be hanged without further ado. In an ordeal by water, the accused was tied into a sack and tossed into a pond. If they floated, they were lying, if they sank—and possibly drowned—they were telling the truth.

By the 1600s, however, such ordeals gave way to a more objective investigation of statements and evidence. Suspects would be questioned in detail, with logical and scientific reasoning applied to what they said. This was the origin of modern legal cross-examination and the presumption that the truth is being told, unless guilt can be proved beyond reasonable doubt. Skilful questioning, debate, and the presentation of evidence were thought sufficient to determine the suspect's truthfulness.

In the nineteenth century, the pseudo-science of phrenology—in which the shape of a person's skull was thought to indicate moral character, intelligence, and criminal tendencies—became an accepted type of "evidence" in criminal courts. Phrenology has long been discredited, but it may have been the first biological attempt at lie detection. Another, the administration of "truth serum," used barbiturates such as scopolamine, sodium amytal, or sodium pentothal, which were thought to "rewire" the brain and compel the suspect to tell the truth. In 1963, however, the U.S. Supreme Court ruled that extracting confessions in this manner was a form of torture and the practice was ruled unconstitutional.

The polygraph, or lie detector, first used in 1924, uses sensors to record changes in breathing rate, blood pressure, and perspiration during questioning. While polygraphs are routinely used in American criminal investigations, suspects and defendants cannot be forced to take them, because the accuracy and interpretation of such results have long been debated. The brain fingerprint, as described in the article below, may have the potential to supersede the polygraph as a technique for determining truth from falsehood.


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Brain fingerprinting is a forensic investigation technique built upon scientific knowledge of memory and the brain. When a suspect is exposed to details of a crime scene, these inevitably trigger a measurable and specific response in the brain known as a MERMER (memory and encoding related multifaceted electroencephalographic response). The MERMER is recorded by electrodes applied to the suspect's scalp and recorded along with the rest of the brain's electrical activity in an electroencephalogram (EEG) trace.

An important feature of EEGs are event-related potentials—spikes of activity that appear after the subject is exposed to specific sounds or sights related to the crime scene. Event-related potentials occur at various periods after the exposure and signify various aspects of brain processing. An evoked potential occurring between 300 and 1,000 milliseconds after exposure is known as a P300 and indicates recognition of information presented in the stimulus.

Used correctly, brain fingerprinting could be an extremely powerful technique to establish truth in criminal investigations. One obvious drawback, however, is that knowledge of the crime scene may be stored in a suspect's brain and may be revealed by the fingerprint, but does not, in itself, establish guilt unless the exposure contains details that could only be known to the perpetrator. An innocent person could easily be aware of crime scene details through court proceedings or media coverage.

Brain fingerprinting could also be used in crime prevention to pinpoint those who have knowledge of plans and plots. For instance, terror suspects might be identified before being allowed entry to a country if their brain fingerprint shows awareness of details of planned attacks.



Burke, Tod W. "Brain fingerprinting: Latest tool for law enforcement." Law & Order June 30, 1999: (47) 6, 28-31.

Web sites

BBC News. "A Brief History of Lying." 〈〉 (accessed January 13, 2006).

Brain Fingerprinting Laboratories "A New Paradigm." 〈〉 (accessed January 13, 2006).