MRIs As Lie Detectors?
Will an MRI of your brain someday be able to tell if you're lying? And, if it can, should it be admissible in Court?
A murder case in Maryland is highlighting a new, and untested, use for MRI’s of a person’s brain that some are claiming could be the new lie detector:
Gary Smith says he didn’t kill his roommate. Montgomery County prosecutors say otherwise.
Can brain scans show whether he’s lying?
Smith is about to go on trial in the 2006 shooting death of fellow Army Ranger Michael McQueen. He has long said that McQueen committed suicide, but now he says he has cutting-edge science to back that up.
While technicians watched his brain during an MRI, Smith answered a series of questions, including: “Did you kill Michael McQueen?”
It may sound like science fiction. But some of the nation’s leading neuroscientists, who are using the same technology to study Alzheimer’s disease and memory, say it also can show — at least in the low-stakes environment of a laboratory — when someone is being deceptive.
Many experts doubt whether the technology is ready for the real world, and judges have kept it out of the courtroom.
Over three days, Montgomery County Circuit Court Judge Eric M. Johnson allowed pretrial testimony about what he called the “absolutely fascinating” issues involved, from the minutiae of brain analysis to the nature of truth and lies. But he decided jurors can’t see Smith’s MRI testing.
“There have been some discoveries that deception may be able to be detected,” Johnson said, but he added that there’s no consensus that the results can be trusted. “These are brilliant people, and they don’t agree.”
Still, researchers and legal experts say they can envision a time when such brain scans are used as lie detectors.
As the article goes on to note, though, the results of polygraph tests are generally not admissible for any purpose in a Court of law in any jurisdiction in the United States. The reason for this is two-fold. First, despite what one see on police and legal dramas, the science behind polygraphs is not at all settled, and there are any number of situations where false negatives or false positives can result. Someone who is innocent but subject to stress and panic attacks could give signals that a polygraph reader would interpret as indicative of lying, while someone who is guilty but a sociopath could lie through their teeth without the machine registering so much as a blip. Additionally, some medical conditions could cause the machine to give off false results. To the extent that the machine isn’t sufficiently reliable, general legal principles would require that results from the machine be barred from being admitted into evidence because they cannot be completely trusted, especially in a criminal case.
The second reason that a polygraph would be inadmissible is because of the extent to which its admission would serve to undermine the entire legal process. As a general rule, the trier of fact — the jury, or in the case of a bench trial, a judge — is considered to be the ultimate judge of the evidence and the testimony of witnesses, including the credibility of the witnesses. Allowing one side or the other to admit into evidence the results of a supposedly scientific test purporting to tell them whether or not a witness, or the Defendant, is telling the truth or not. The obvious danger, of course, is that juries would give undue weight to the results of this test as opposed to their own judgment of the credibility of the witnesses. In essence, by allowing evidence such as this into Court we’d be making the technology the judge of a Defendant’s guilt or innocence rather than the trier of fact. That would create a completely alien and, as noted above, unreliable legal system the results of which we can’t possibly imagine at this point.
It would appear that the situation is the same with brain scans:
[Assistant professor of psychiatry at the University of California at San Diego Frank]Haist said the tests can’t conclusively determine when someone is being honest.
“The MRI is not a truth machine,” he said. “I can’t say with certainty that he is telling the truth.”
Other experts said the scans don’t prove whether Smith is being either deceptive or truthful.
New York University neuroscientist Liz Phelps told the court that there is “no evidence” that the scans are useful in revealing a “real-world, self-serving lie.”
Stanford neuroscience professor Anthony D. Wagner, called by prosecutors, said that “it’s premature” to use the tests in court. “I, personally, don’t know how the literature is going to play out in the long run. . . . I’m not concluding that it can never be shown,” he said.
Over more than a decade, researchers have devised a series of experiments using those scans to see what lying looks like inside the brain. A University of Pennsylvania study asked subjects to lie about holding a five of clubs. In another study, men in Hong Kong were shown images and asked to lie about their feelings about them. Accuracy rates for picking out the deceptions topped 90 percent in some cases.
Harvard Medical School assistant professor Giorgio Ganis hit 100 percent in a study that asked students to lie when they saw their birth date. “We probably got a little bit lucky,” Ganis said.
The Harvard birth-date experiment was cited by both sides as an example of the power the MRI might wield and its potential shortcomings.
Researchers put undergraduates in a functional MRI and showed them a series of irrelevant dates. The students were asked to press a “no” button if the date didn’t mean anything to them. Ganis also threw the subjects’ birthdays into the mix, telling them to lie and press “no” when that date displayed. Using a computer trained to recognize brain patterns, the researchers could accurately detect when the students were being deceptive.
But the students also were taught how to outwit the machine by “imperceptibly” moving a finger or a toe — basically to imagine moving them — when irrelevant dates appeared. That itself made the dates relevant, Ganis said, and the accuracy rate plummeted to 33 percent. “You are recalling something meaningful when you see the meaningless dates,” Ganis said. “The MRI can’t tell what’s going on.”
Ganis said that he has nothing against using MRIs for lie detection in the future but that more needs to be learned first about how the guilty could use similar tactics to trick the machine.
It’s unclear to me whether we’d ever get to the point where this technology can be considered sufficiently reliable to be used in Court. Polygraph technology has advanced greatly in recent decades, and it is commonly used in his security situations in the public and government sectors, but it’s still not considered appropriate for use in Court, and I’m not sure that it ever will or that it should. Putting the legal system in the hands of machines doesn’t strike me as a good idea.
Ultimately, the Judge in this Maryland case ruled that the brain scan could not be admitted into evidence, which strikes me as the right outcome. I doubt this will be the last time that an American court has to deal with this issue.
Graphic via The Washington Post