How Polygraphs Work—And Why They Aren't Admissible in Most Courts

iStock/Sproetniek
iStock/Sproetniek

The truth about lie detectors is that we all really want them to work. It would be much easier if, when police were faced with two contradictory versions of a single event, there was a machine that could identify which party was telling the truth. That’s what the innovators behind the modern-day polygraph set out to do—but the scientific community has its doubts about the polygraph, and all over the world, it remains controversial. Even its inventor was worried about calling it a "lie detector."

AN OFF-DUTY INVENTION

In 1921, John Larson was working as a part-time cop in Berkeley, California. A budding criminologist with a Ph.D. in physiology, Larson wanted to make police investigations more scientific and less reliant on gut instinct and information obtained from "third degree" interrogations.

Building on the work of William Moulton Marston, Larson believed that the act of deception was accompanied by physical tells. Lying, he thought, makes people nervous, and this could be identified by changes in breathing and blood pressure. Measuring these changes in real-time might serve as a reliable proxy for spotting lies.

Improving upon previously developed technologies, Larson created a device that simultaneously recorded changes in breathing patterns, blood pressure, and pulse. The device was further refined by his younger colleague, Leonarde Keeler, who made it faster, more reliable, and portable and added a perspiration test.

Within a few months, a local newspaper ​convinced Larson to publicly test his invention on a man suspected of killing a priest. Larson's machine, which he called a cardio-pneumo psychogram, indicated the suspect’s guilt; the press dubbed the invention a lie detector.

Despite the plaudits, Larson would become skeptical about his machine’s ability to reliably detect deception—especially in regards to Keeler’s methods which amounted to “a psychological third-degree." He was concerned that the polygraph had never matured into anything beyond a glorified stress-detector, and believed that American society had put too much faith in his device. Toward the end of his life, he would refer to it as “a Frankenstein’s monster, which I have spent over 40 years in combating.”

But Keeler, who patented the machine, was much more committed to the lie-detection project, and was eager to see the machine implemented widely to fight crime. In 1935, results of Keeler’s polygraph test were admitted for the first time as evidence in a jury trial—and secured a conviction.

HOW IT WORKS

In its current form, the polygraph test measures changes in respiration, perspiration, and heart rate. Sensors are strapped to the subject's fingers, arm, and chest to report on real-time reactions during interrogation. A spike on these parameters indicates nervousness, and potentially points to lying.

To try to eliminate false-positives, the test ​relies on "control questions."

In a murder investigation, for instance, a suspect may be asked relevant questions such as, "Did you know the victim?" or "Did you see her on the night of the murder?" But the suspect will also be asked broad, stress-inducing control questions about general wrongdoing: "Did you ever take something that doesn't belong to you?" or "Did you ever lie to a friend?" The purpose of the control questions is to be vague enough to make every innocent subject anxious (who hasn't ever lied to a friend?). Meanwhile, a guilty subject is likely to be more worried about answering the relevant questions.

This difference is what the polygraph test is about. According to the American Psychological Association, “A pattern of greater physiological response to relevant questions than to control questions leads to a diagnosis of ‘deception.’” They proclaim that, "Most psychologists agree that there is little evidence that polygraph tests can accurately detect lies."

But a diagnosis of deception doesn’t necessarily mean that someone has actually lied. A polygraph test doesn’t actually detect deception directly; it only shows stress, which was why Larson fought so hard against it being categorized as a "lie detector." Testers have a variety of ways to infer deception (like by using control questions), but, according to the American Psychological Association, the inference process is “structured, but unstandardized” and should not be referred to as “lie detection.”

And so, the validity of the results remains a subject of debate. Depending on whom you ask, the reliability of the test ranges from near-certainty to a coin toss. The American Polygraph Association claims the test has an almost 90 percent accuracy rate. But many psychologists—and even some ​police officers—contend that the test is ​biased toward finding liars and has a 50 percent chance of hitting a false-positive for honest people.

NOT QUITE THE SAME AS FINGERPRINTS

Most countries have traditionally been skeptical about the polygraph test and only a handful have incorporated it into their legal system. The test remains most popular in the United States, where many police departments rely on it to extract confessions from suspects. (In 1978, former CIA director Richard Helms argued that that's because "Americans are not very good at" lying.)

Over the years, the U.S. Supreme Court has issued numerous rulings on the question of whether polygraph tests should be admitted as evidence in criminal trials. Before Larson’s invention, courts treated lie-detection tests with suspicion. In a 1922 case, a judge prohibited the results of a pre-polygraph lie detector from being presented at trial, worrying that the test, despite its unreliability, could have an unwarranted sway on a jury’s opinion.

Then, after his polygraph results secured a conviction in a 1935 murder trial (through prior agreement between the defense and prosecution), Keeler—Larson’s protégé—asserted that “the findings of the lie detector are as acceptable in court as fingerprint testimony.”

But numerous court rulings have ensured that this won’t be the case. Though the technology of the polygraph has continued to improve and the questioning process has become more systematic and standardized, scientists and legal experts remained divided on the device's efficacy.

A 1998 Supreme Court ruling ​concluded that as long as that’s the case, the risk of false positives is too high. The polygraph test, the court concluded, enjoys a scientific “aura of infallibility,” despite the fact “there is simply no consensus that polygraph evidence is reliable,” and ruled that passing the test cannot be seen as proof of innocence. Accordingly, taking the test must remain voluntary, and its results must never be presented as conclusive.

Most importantly: The court left it up to the states to decide whether the test can be presented in court at all. Today, 23 states allow polygraph tests to be admitted as evidence in a trial, and many of those states require the agreement of both parties.

Critics of the polygraph test claim that even in states where the test can't be used as evidence, law enforcers often use it as a tool to ​bully suspects into giving confessions that then can be admitted.

“It does tend to make people frightened, and it does make people confess, even though it cannot detect a lie,” Geoff Bunn, a psychology professor at Manchester Metropolitan University, told The Daily Beast.

But despite criticism—and despite an entire ​industry of former investigators offering to teach individuals how to beat the test—the polygraph is still used ​widely in the United States, mostly in the process of job applications and security checks.

6 Fun Backgrounds to Use on Your Next Video Call

You might be stuck in the living room, but it doesn't have to look like it.
You might be stuck in the living room, but it doesn't have to look like it.
Ridofranz/iStock via Getty Images

If you’re struggling to find a perfectly decorated wall in your house to serve as the backdrop for your video calls with friends, family, and coworkers, we have good news: Video conferencing platform Zoom lets you customize your very own virtual background.

To do it, log into your Zoom account, go to “Settings” on the left side of your screen, and choose the "Meeting" tab. Scroll down to the “In Meeting (Advanced)” section, and then scroll down farther to make sure the “Virtual background” option is enabled. After that, open the Zoom application on your desktop, click on the “Settings” wheel in the upper right corner, and go to “Virtual Background.” There are a few automatic options, but you can choose your own image from your computer files by clicking on the plus-sign icon.

Now, the only thing left to do is decide which image will best set the tone for your next video call. From the New York Public Library’s Rose Reading Room to Schitt’s Creek’s Rosebud Motel, here are six of our favorites.

1. The Rosebud Motel lobby from Schitt’s Creek

schitt's creek rose motel lobby
It's not the Ritz-Carlton.
CBC

You can imagine that David is just out of frame, doing his best to carry on a silent—albeit with lots of expressive gesturing—conversation with Stevie at the front desk. (More Schitt's Creek backgrounds here.)

2. Carl and Ellie’s house from Up

carl and ellie's house from up
Balloons not included.
Walt Disney Pictures

If you’re hoping to create a calming atmosphere, look no further than the cozy little sitting room where Carl and Ellie grew old together in 2009's Up. (More Pixar backgrounds here.)

3. The attic study from Knives Out

knives out attic study
Nothing bad has ever happened here.
Lionsgate

If your own study isn’t quite teeming with intriguing souvenirs and leather-bound volumes, feel free to borrow this one from the mansion in 2019’s Knives Out. (More Knives Out backgrounds here.)

4. The USS Enterprise from Star Trek

star trek's uss enterprise bridge
A great way to get your coworkers to fess up to being huge Trekkies.
TrekCore.com, Twitter

Blame your spotty internet connection on the fact that you’re traveling through the galaxy at the speed of light with this background from the bridge of Star Trek’s USS Enterprise. (More Star Trek backgrounds here.)

5. The New York Public Library’s Rose Reading Room

new york public library reading room
You reserve the right to shush any coworkers who forgot to mute themselves.
New York Public Library

Bibliophiles who can’t make it to the library can still pay a virtual visit to the sumptuous Rose Main Reading Room at the New York Public Library’s iconic Fifth Avenue location. (More New York Public Library backgrounds here.)

6. The Werk Room from RuPaul’s Drag Race

rupaul's drag race werk room
Sashay away from the screen if you're taking a bathroom break during the call.
VH1

Dazzle your coworkers by calling in from the vibrant room where all the magic—and most of the drama—happens on RuPaul’s Drag Race. If you happen to be decked out in an ensemble made entirely of things you found at the Dollar Store, even better. (More RuPaul's Drag Race backgrounds here.)

Turn Your Favorite Photos Into Works of Art With Google’s Art App

Edvard Munch's "The Scream"
Edvard Munch's "The Scream"
Edvard Munch, Wikimedia Commons // Public Domain

If your local art museum is closed, a new app from Google Arts & Culture will make the photos in your camera roll worthy of gallery consideration. As Gizmodo reports, the Art Transfer feature uses artificial intelligence to reimagine any image you upload in the style of a famous artist.

If you've already downloaded Arts & Culture for Android or iOS, hit the camera icon at the bottom of the app and select Art Transfer. From here, you can either snap a photo or choose an existing picture saved on your phone. Google then gives you a variety of art styles to choose from. You can transform your cat into Edvard Munch's The Scream, for example, or turn your brunch pic from last month into a piece of Yayoi Kusama pop art.

The feature doesn't just apply filters; it uses machine learning to edit the colors, textures, and even shapes in the image you upload.

Dog image inspired by Man from Naples.
Michele Debczak/Mental Floss, Google Arts & Culture

Pizza picture inspired by The Scream.
Michele Debczak/Mental Floss, Google Arts & Culture

Two years ago, Google Arts & Culture rolled out a similar feature that matched users' selfies to their art lookalikes. The difference with this one is that instead of showing you existing art, it creates an entirely new image by combining your photo with a famous artwork.

You can download Arts & Culture for free today from the App Store or Google Play. After having fun with the new feature, you can use the app to virtually explore landmarks, museums, and other cultural institutions from the comfort of your home.

[h/t Gizmodo]

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