Can the polygraph test really spot a lie?

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Rund Abdelfatah (0:28)

It's springtime in Berkeley, California, 1921 A group of college-aged women are whispering to one another in the halls of their dormitory.

A man named John Larson arrives on campus carrying his brand-new invention, the cardioneumopsychograph, an early version of the polygraph machine.

Ken Alder (0:51)

And there's been telfering in the sorority, including a diamond ring's gone missing and a bunch of other stuff. And Larson is asked to solve the crime after the old school police guys just can't do it. They just started asking these women, they realize it's an inside job, but they don't know who did it.

Rund Abdelfatah (1:08)

Larson is a trained physiologist who just joined the police force. This is The Lie Detectors' first trial run.

One after another, he asks these women questions. And when he gets to suspect number 14, she seems nervous.

Ken Alder (1:24)

And when he asks her whether she stole the diamond ring, she gets furious, pulls off the apparatus and runs out of the room. And then over the next few days, the police sort of follow her and hound her, and eventually she confesses to the crime.

Rund Abdelfatah (1:38)

The Lie Detector had solved its first case, or so it seemed.

Ken Alder (1:43)

Did she really do it? Larson has doubts later whether or not she is in fact guilty. And the crimes continued, and she clearly had psychological issues. She herself admitted to this. And so the psychological effect of the Lie Detectors is to make people feel incredibly guilty. And they do confess to things.

Whether those confessions are true has been a different question, right?

Rund Abdelfatah (2:06)

This is Throughline from NPR. I'm your host, Rund Abdelfatah. We got an email from a listener named Frankie, who said they were asked to take a polygraph test as part of the hiring process for a job working for Orange County in Florida. Frankie had the impression that these tests were pseudoscience and can't actually detect when someone is telling a lie.

Frankie wanted to know, what's the backstory of these tests? And if they're junk science, why are they still used in the workplace?

Ken Alder (2:37)

You know, it's always fascinated me that there's this device that claims to tell the truth. And it's a story of science that that would be possible. Always intrigued me.

Rund Abdelfatah (2:46)

This is Ken Alder. He's a professor of history at Northwestern University. He's also the author of The Lie Detectors, The History of an American Obsession. And it is an American obsession.

The polygraph may be most familiar to us in the context of daytime TV. Think The Morey Show.

SPEAKER_4 (3:11)

During your relationship with Destiny, have you ever had sexual intercourse with any other women? You said no. The Lie Detector determined that was a lie for more than five women.

Rund Abdelfatah (3:20)

The Lie Detector is also used in police investigations.

SPEAKER_5 (3:24)

Police wanted a confession. Duxbury agreed to take a polygraph test that experts say he failed.

Rund Abdelfatah (3:31)

The National Academy of Sciences and the Office of Technology Assessment under Congress have both conducted studies on the effectiveness of the lie detector test.

Ken Alder (3:41)

And time and time again come to the conclusion that it's at best ineffective and quite possibly and frequently counterproductive.

Rund Abdelfatah (3:50)

And yet, we just can't seem to quit it.

SPEAKER_6 (3:53)

Some federal agencies are ramping up efforts to identify leakers. That includes the FBI, which in recent weeks has been using polygraphs. That's right, the so-called lie detector test.

Rund Abdelfatah (4:05)

When we come back, Ken Alder explains why we got the polygraph test in the first place, and why you still might encounter it in the workplace.

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