Brain Imaging Technology Not Ready for Forensic Use, Says Prof

February 08, 2008 - News Release

Technology that can monitor brain activity is moving into the world of forensic investigation faster than it should, according to new research by a University of Guelph psychology professor.

In a first-ever analysis of the research on Brain Fingerprinting and other neuroimaging techniques, Dan Meegan has found that the technology has not been proven reliable enough to determine whether someone is guilty or innocent of a crime.

"There's a huge amount of interest in this technology coming from the legal community, and if it's being used to determine whether people are innocent or guilty, then it's important that we find out if these techniques are reliable," said Meegan, who specializes in memory-related research. "From a scientific perspective, I can tell you that these techniques aren't ready."

To date, Brain Fingerprinting is being used in criminal investigations in the United States and has even been accepted as evidence in court.

The technology involves attaching electrodes to a suspect's scalp and then monitoring how the brain reacts to certain stimuli, such as photos or words, related to a crime scene that only the person who committed the crime would know.

The brain produces different electrical signals based on whether the person recognizes the stimuli or not. These signals are captured by the electrodes and analyzed. Similar testing can be done with magnetic resonance imaging technology, where blood flow in the brain is used to determine whether the brain recognizes, or has memory of, certain stimuli.

Investigators and attorneys then use the test results as evidence to support a person's guilt or innocence.

Meegan's research, which was published this week in American Journal of Bioethics, found that the level of accuracy of neuroimaging techniques is not as high as believed.

"There is evidence of a substantial risk of the technology failing to catch people who are guilty, so results that find a person innocent are completely meaningless," he said.

He also found that a majority of the research conducted on the accuracy of this technology was done in a lab setting, where the researcher has more control over the circumstances and subjects than would be possible in a real criminal investigation.

"With an actual investigation, there are a number of factors that can influence a person's ability to recognize, or have memory of, certain details."

In some cases, weeks or even months will pass before a suspect is identified, he said.

"Researchers don't wait months to do tests, and this time lapse is important to consider because it can hinder people's memory of the crime and their ability to recognize certain stimuli."

In lab settings, researchers can control which stimuli they want a subject to remember by showing it to the person in advance of the test.

But when a person is committing a crime, he or she isn't often taking mental notes of the surroundings may not be able to remember certain details of the crime, said Meegan. Suspects can also be under the influence of drugs when committing a crime, which can impair their ability to remember details.

There's also an element of high emotion when a crime suspect is taking the test compared with a participant in a lab study, and this level of emotion can affect results, he added.

"There needs to be more research done involving circumstances that mimic a forensic investigation before neuroimaging can be established as a reliable tool. Until then, scientists need to put the brakes on using this technology in actual investigations."

There is a story on Meegan's study in Friday's National Post.

Prof. Dan Meegan
Department of Psychology
519-824-4120, Ext. 54998

For media questions, contact Communications and Public Affairs: Lori Bona Hunt, 519-824-4120, Ext. 53338, or Deirdre Healey, Ext. 56982,

University of Guelph
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Guelph, Ontario, N1G 2W1