Can an MRI machine also act as a lie detector?

Joe Larson, one of the inventors of the polygraph machine, demonstrates it in the 1930s. The validity of the polygraph has come into question increasingly over past decades.
Pictorial Parade/Getty Images

In the 1930s, Leonard Keeler -- one of the men who developed what we recognize today as the modern polygraph -- marketed "The Magic Lie Detec­tor," a tool used during interrogations [source: Larson]. The appeal of the technology, which can give an interrogator insight in the truthfulness of a suspect's tale, caught on quickly. Since then, history has proven that the polygraph isn't very magical, neither in its machinations, nor in the validity of its results.

MRI Image Gallery

The polygraph uses a combination of physiological measurements -- like blood pressure, heart rate and skin temperature -- to determine whether a person may be lying during a series of questions. The data rendered by the test is analyzed afterward to determine whether the person questioned exhibited signs of stress, an indication of deception.


But there's a two-sided problem with the polygraph that has become increasingly clear over the course of the past century: A person who can remain cool under pressure can beat a polygraph, and conversely, a person who doesn't handle stressful situations well may be inaccurately labeled a liar.

Due to the perceived threat of terrorism that was born out of the Sept. 11 attacks, the U.S. government decided that a better, more reliable way of determining truth was needed. It appears that MRI technology has emerged to fill the void created by a convergence of the lack of faith in polygraphs and the urgency to know friend from foe following Sept. 11.

MRI -- magnetic resonance imaging -- is a technology that has been in ever-increasing use since the first model was built by Raymond Damadian and his colleagues in 1976. As recently as just over 100 years ago, physicians routinely paid grave robbers to steal bodies for their use as cadavers. It was dissection of these cadavers that helped expand our working knowledge of human anatomy. X-ray photographs were the next big leap in this field of study, providing us a view into the human body without needless incision.

Now, MRI has revolutionized the field of anatomical study. Rather than investigating the inner workings of the human body through observation of dead organs or examining flat, cloudy images of bone and tissue, MRI allows radiologists to see real-time, 3-D models of human parts.

MRIs use powerful magnets to charge hydrogen protons within cells. A radio frequency is broadcast at these protons, which absorb the frequency and reflect it back at a receiver. This information is translated into an image of the area scanned. Through this method, MRIs have determined the exact location and size of tumors and mapped the extent of a stroke -- all before scalpel was ever put to skin. In these ways and many others, this technology has saved lives.

But thanks to some emerging research, it's becoming clear that an MRI could also serve a non-clinical purpose -- as a lie detector. Read on to find out how MRIs work as lie detectors and why some people are opposed to this use.


How MRI Lie Detectors Work

An MRI image of an overactive amygdala,
Photo courtesy National Library of Medicine/National Institutes of Health

An MRI uses a magnetic band as a scanner to peer through tissue and bone to see within the human body. To use an MRI as a lie detector, however, an fMRI -- functional MRI -- must be used. FMRIs are connected to specialized software able to not only display, but also analyze the images the MRI produces.

Within these pictures, different parts of the body are shown highlighted in different colors. The more active the system, the brighter the area. For use in brain scans, the fMRI analyzes blood flow to specific regions of the brain. Neurons in the brain need blood to operate, and a sudden demand for blood suggests activation of a region.


Imagine being in an MRI while you ride a bike. If you decide to turn left, the MRI image could conceivably show the different regions of the brain that are involved in the process of turning left. One part tells your musculoskeletal system to shift your balance, another region tells the eyes to look both ways for oncoming traffic, and another maintains the pedaling motion produced by your legs.

By studying the images, researchers could map the systematic procedure your brain went through to produce the left turn. What's more, neurologists are now finding they can see the process by which you made the decision to turn left, rather than turning right or staying straight.

It's through analysis of these regions and knowledge of what function for which each region is responsible that has led to the possibility that MRIs can predict truth-telling.

The idea for the use of MRIs as lie detectors came from some very innocent research. To investigate whether children diagnosed with attention deficit disorder (ADD) were unable to tell lies, University of Pennsylvania psychiatrist Daniel Langleben conducted MRI scans on young patients with the disorder. Langleben discovered that deception activates regions in the pre-frontal cortex. These were perhaps the first snapshots ever taken of lies.

Langleben's findings have been supported by other researchers. At Temple University, Scott Faro conducted a study whereby he asked some volunteers to lie and others to tell the truth while in an MRI. He found that more regions of the brain -- including those same pre-frontal regions Langleben identified -- are used during deception than in truth-telling.

And at the Max Planck Institute in Germany, John-Dylan Haynes conducted an experiment in which he asked students to decide whether they would add or subtract two numbers before they saw them. Haynes fed a portion of the 250 tests conducted for each student into a computer algorithm, which then searched for patterns in the images. After excluding the sample tests, the computer was accurately able to predict whether a student would add or subtract -- based solely on the images of the student's brain -- 71 percent of the time.

The results of these experiments show that much of what we understand as our decision-making process -- including the decision to lie -- occurs at the front of our brains. What's more, we can now see these processes. In effect, through MRIs, we have reached the point where we can read a person's mind.

The field of using MRIs as lie detectors is still in its infancy. But with the amount of attention being paid to the research -- as well as the funding being poured into it -- there's little doubt that it will advance by leaps and bounds over the coming decades. The question is, should we use this technology? Read the next page to explore the pros and cons of reading people's minds.


MRI Mind Reading: Pitfalls and Possibilities

Gary Ridgway, the Green River Killer, was given a polygraph, which he deceived. He was let go and eventually killed 48 women before he was finally prosecuted.
Josh Trujillo-Pool/Getty Images

Turning backward to gaze upon science's investigation into the human mind over the past two centuries, it's hard not to see phrenology, one of the great failures of science. Phrenology is the study of the shape of the skull, as well as bumps and depressions in the scalp. Phrenologists claimed that by analyzing these telltale signs, a person's intelligence, breeding and morality could be distinguished. Although it enjoyed international acclaim, phrenology was eventually -- and totally -- discredited.

Some wonder if the use of MRIs for mind reading is the new frontier of this old, discredited science. Phrenology was used to devalue entire groups of people, as some fear MRI mind mapping may be as well.


There are seemingly limitless ways that the MRI could be used to benefit mankind. MRIs could end up as a way to effectively read a person's thoughts before he even speaks them. The technology could allow law enforcement to see whether someone is lying or telling the truth. MRIs could thwart the next terrorist plot, or catch the next Green River Killer (this serial killer subverted a polygraph test and was let go).

Practically applied, an MRI could scan passengers at airports before they boarded a plane. Anyone displaying thoughts associated with hijacking or mass murder could be stopped before they committed such an act. Spies could be rooted out from clandestine service, and sexual predators could be identified before they ever claimed a first victim.

But many of the scientists conducted research say that this field is far too young to be currently used for any of these applications. The results are still too hazy. For one, although neurologists have identified certain parts of the brain which they associated with certain decisions, they're still unsure as to exactly why these processes take place. It's sort of like looking at a dark cloud and watching rain begin to fall from it, without any understanding of the process which creates the rain.

There are other, more easily conquered problems with using MRI as a window into the mind. MRIs are huge, hulking machines, which makes them difficult to transport. And for an MRI scan to be successful, the subject must lie perfectly still until the scan is completed. Even a movement as subtle as an eyebrow twitch can produce a useless scan.

But even if the technology does advance so MRIs are portable and can accurately scan a moving (and possibly unaware) person, should we use them for this application?

That's what's being posed by the Center for Cognitive Liberty and Ethics, a think tank that ponders the right of privacy for the thoughts of individuals. The problem with reading a person's thoughts, says the CCLE, is that technology like this could easily lead to scans of all of us to identify potential future criminals.

As justice in the Western world currently stands, people are convicted for crimes they're accused of committing rather than for crimes they may commit at some point in the future. Were MRIs used to scan minds to determine propensity towards crime, would this change? Could a future criminal find himself imprisoned or sequestered from society before he committed a crime?

Ultimately, the question is which is more valuable to society, personal liberty or personal security? This question has real applications right now, but if mind reading technology continues to advance, a new question may emerge: Do we have a right to privacy for our thoughts?


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More Great Links


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