The Face That Launched a Thousand False Positives

May 27, 2016
Posted by Jay Livingston

What bothered the woman sitting next to him wasn’t just that the guy was writing in what might have been Arabic (it turned out to be math). But he also looked like a terrorist. (WaPo story here.)

We know what terrorists look like. And now an Israeli company, Faception, has combined big data with facial recognition software to come up with this.

According to their Website:

Faception can analyze faces from video streams, cameras, or . . . databases. We match an individual with various personality traits or types such as an Extrovert, a person with High IQ, Professional Poker Player or a Terrorist.

My first thought was, “Oh my god, Lombroso.”

If you’ve taken Crim 101, you might remember that Lombroso, often called “the father of criminology,” had the idea that criminals were atavisms, throwbacks to earlier stages of human evolution, with different skull shapes and facial features. A careful examination of a person’s head and face could diagnose criminality – even the specific type of lawbreaking the criminal favored. Here is an illustration from an 1876 edition of his book. Can you spot the poisoner, the Neapolitan thief, the Piedmont forger?

(Click on the image for a larger view.)

Criminology textbooks still mention Lombroso, though rarely as a source enlightenment. For example, one book concludes the section on Lombroso, “At this point, you may be asking: If Lombroso, with his ideas about criminal ears and jaws, is the ‘father of criminology,’ what can we expect of subsequent generations of criminologists?”

Apparently there’s just something irresistible in the idea that people’s looks reveal their character. Some people really do look like criminals, and some people look like cops.* Some look like a terrorist or a soccer mom or a priest. That’s why Hollywood still pays casting directors. After all, we know that faces show emotion, and most of us know at a glance whether the person we’re looking at is feeling happy, angry, puzzled, hurt, etc. So it’s only logical that a face will reveal more permanent characteristics. As Faception puts it, “According to social and life science research, our personality is determined by our DNA reflected in our face.” It’s not quite true, but it sounds plausible.

The problem with this technique is not the theory or science behind it, and probably not even its ability to pick out terrorists, brand promoters, bingo players, or any of their other dramatis personae in the Faception cast of characters. The problem is false positives. Even when a test is highly accurate, if the thing it’s testing for is rare, a positive identification is likely to be wrong. Mammograms, for example, have an accuracy rate as high as 90%. Each year, about 37 million women in the US are given mammograms. The number who have breast cancer is about 180,000. The 10% error rate means that of the 37 million women tested, 3.7 million will get results that are false positives. It also means that for the woman who does test positive, the likelihood that the diagnosis is wrong is 95%.**

Think of these screening tests as stereotypes. The problem with stereotypes is not that they are wrong; without some grain of truth, they wouldn’t exist. The problem is that they have many grains of untruth – false positives. We have been taught to be wary of stereotypes not just because they denigrate an entire class of people but because in making decisions about individuals, those stereotypes yield a lot of false positives.  

Faception does provide some data on the accuracy of its screening. But poker champions and terrorists are rarer even than breast cancer. So even if the test can pick out the true terrorist waiting to board the plane, it’s also going to pick out a lot of bearded Italian economists jotting integral signs and Greek letters on their notepads.

(h/t Cathy O’Neil at

* Some people look like cops. My favorite example is the opening of Richard Price’s novel Lush Life – four undercover cops, though the cover they are under is not especially effective.

The Quality of Life Task Force: four sweatshirts in a bogus taxi set up on the corner of Clinton Street alongside the Williamsburg Bridge off-ramp to profile the incoming salmon run; their mantra: Dope, guns, overtime; their motto: Everyone’s got something to lose. 
At the corner of Houston and Chrystie, a cherry-red Denali pulls up alongside them, three overdressed women in the backseat, the driver alone up front and wearing sunglasses.
The passenger-side window glides down . “Officers, where the Howard Johnson hotel at around here ...”
“Straight ahead three blocks on the far corner,” Lugo offers.
“Thank you.” [. . .]
The window glides back up and he shoots east on Houston.
“Did he call us officers?”
“It’s that stupid flattop of yours.”
“It’s that fuckin’ tractor hat of yours.”

It wasn’t the haircut or the hat. They just looked like cops.

** The probability that the diagnosis is correct is 5% – the 180,000 true positives divided by the 3.7 million false positives plus the 180,000 true positives – roughly 180,000 / 3,900,000. (I took this example from Howard Wainer’s recent book, Truth and Truthiness.)

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