Can an MRI machine also act as a lie detector?

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.

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?