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Should Brain Scans Be Used as Lie-Detectors?

Should Brain Scans Be Used as Lie-Detectors? Advancements in electronic and magnetic imaging of the brain are beginning to blur the lines on when technology should be used in a court of law.

In a new study, researchers used fMRI brain scans to detect whether a person recognized scenes from their own lives, as captured in some 45,000 images by digital cameras.

Researchers view the study as an example of the capabilities and limits of brain-based technology for detecting memories, a technique being considered for use in legal settings.

“The advancement and falling costs of fMRI, EEG, and other techniques will one day make it more practical for this type of evidence to show up in court,” says Francis Shen of the University of Minnesota Law School.

“But technological advancement on its own doesn’t necessarily lead to use in the law.”

However, as the legal system desires to use more empirical evidence, neuroscience and the law are intersecting more often than in previous decades.

In U.S. courts, neuroscientific evidence has been used largely in cases involving brain injury litigation or questions of impaired ability.

In some cases outside the United States, however, courts have used brain-based evidence to check whether a person has memories of legally relevant events, such as a crime.

New companies also are claiming to use brain scans to detect lies – although judges have not yet admitted this evidence in U.S. courts.

These developments have rallied some in the neuroscience community to take a critical look at the promise and perils of such technology in addressing legal questions.

A case 2008 in Mumbai, India — in which a judge cited EEG evidence as indicating that a murder suspect held knowledge about the crime that only the killer could possess — inspired Anthony Wagner to test fMRI uses for memory detection.

It appeared that the brain data held considerable sway,” says Wagner, a cognitive neuroscientist at Stanford University. However, Wagner points out that the methods used in that case have not been subject to extensive peer review.

Since then, Wagner and colleagues have conducted a number of experiments to test whether brain scans can be used to discriminate between stimuli that people perceive as old or new, as well as more objectively, whether or not they have previously encountered a particular person, place, or thing.

To date, Wagner and colleagues have had success in the lab using fMRI-based analyses to determine whether someone recognizes a person or perceives them as unfamiliar, but not in determining whether in fact they have actually seen them before.

In a new study Wagner’s team sought to take the experiments out of the lab and into the real world by outfitting participants with digital cameras around their necks that automatically took photos of the participants’ everyday experiences. Over a multi-week period, the cameras yielded 45,000 photos per participant.

Wagner’s team then took brief photo sequences of individual events from the participants’ lives and showed them to the participants in the fMRI scanner, along with photo sequences from other subjects as the control stimuli.

The researchers analyzed their brain patterns to determine whether or not the participants were recognizing the sequences as their own.

“We did quite well with most subjects, with a mean accuracy of 91 percent in discriminating between event sequences that the participant recognized as old and those that the participant perceived as unfamiliar, ” Wagner says.

“These findings indicate that distributed patterns of brain activity, as measured with fMRI, carry considerable information about an individual’s subjective memory experience – that is, whether or not they are remembering the event.”

In another new study, Wagner and colleagues tested whether people can “beat the technology” by using countermeasures to alter their brain patterns.

Back in the lab, the researchers showed participants individual faces and later asked them whether the faces were old or new.

“Halfway through the memory test, we stopped and told them ‘What we are actually trying to do is read out from your brain patterns whether or not you are recognizing the face or perceiving it as novel, and we’ve been successful with other subjects in doing this in the past. Now we want you to try to beat the system by altering your neural responses.'”

The researchers instructed the participants to think about a familiar person or experience when presented with a new face, and to focus on a novel feature of the face when presented a previously encountered face.

“In the first half of the test, during which participants were just making memory decisions, we were well above chance in decoding from brain patterns whether they recognized face or perceived it as novel.

“However, in the second half of the test, we were unable to classify whether or not they recognized the face nor whether the face was objectively old or new,” Wagner says.

This capability could mean that that a suspect could use such measures to try to mask the brain patterns associated with memory.

Wagner says that his work to date suggests that the technology may have some utility in reading out brain patterns in cooperative individuals but that the uses are much more uncertain with uncooperative individuals.

However, Wagner stresses that the method currently does not distinguish well between whether a person’s memory reflects true or false recognition.

He believes it is premature to consider such evidence in the courts because many additional factors need future testing, including the effects of stress, practice, and time between the experience and the memory test.

Experts say that a general challenge to the use of neuroscientific evidence in legal settings is that most studies are at the group rather than the individual level.

“The law cares about a particular individual in a particular situation right in front of them,” Shen says, and the science often cannot speak to that specificity.

Currently, this challenge of making individualized inference from group-based data has slowed use of neuroscience evidence in the court.

However, experts believe advances in technology will undoubtedly accelerate collaboration between neuroscientists and legal scholars.

Source: Cognitive Neuroscience Society

Should Brain Scans Be Used as Lie-Detectors?

Rick Nauert PhD

Rick Nauert, PhDDr. Rick Nauert has over 25 years experience in clinical, administrative and academic healthcare. He is currently an associate professor for Rocky Mountain University of Health Professionals doctoral program in health promotion and wellness. Dr. Nauert began his career as a clinical physical therapist and served as a regional manager for a publicly traded multidisciplinary rehabilitation agency for 12 years. He has masters degrees in health-fitness management and healthcare administration and a doctoral degree from The University of Texas at Austin focused on health care informatics, health administration, health education and health policy. His research efforts included the area of telehealth with a specialty in disease management.

APA Reference
Nauert PhD, R. (2018). Should Brain Scans Be Used as Lie-Detectors?. Psych Central. Retrieved on November 29, 2020, from
Scientifically Reviewed
Last updated: 8 Aug 2018 (Originally: 18 Apr 2013)
Last reviewed: By a member of our scientific advisory board on 8 Aug 2018
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