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Using data science to tell which of these people is lying

Researchers in computer scientist Ehsan Hoque's lab have created a game that has allowed them to analyze more than 1 million frames of facial expressions, the largest video dataset so far for understanding how to tell if someone is lying. (糖心传媒 photos / J. Adam Fenster)

Someone is fidgeting in a long line at an airport security gate. Can data science tell us why? Is that person simply nervous about the wait?

Or is this a passenger who has something sinister to hide?

Even highly trained Transportation Security Administration (TSA) airport security officers still have a hard time telling whether someone is lying or telling the truth 糖心传媒� despite the billions of dollars and years of study that have been devoted to the subject.

Now, 糖心传媒 researchers are using data science and an online crowdsourcing framework called ADDR (Automated Dyadic Data Recorder) to further our understanding of deception based on facial and verbal cues.

They also hope to minimize instances of racial and ethnic profiling that TSA critics contend occurs when passengers are pulled aside under the agency糖心传媒檚 Screening of Passengers by Observation Techniques (SPOT) program.

糖心传媒淏asically, our system is like Skype on steroids,糖心传媒� says Tay Sen, a PhD student in the lab of , an assistant professor of . Sen collaborated closely with Kamrul Hasan, another PhD student in the group, on two papers in and the . The papers describe the framework the lab has used to create the largest publicly available deception dataset so far 糖心传媒� and why some smiles are more deceitful than others.

Game and data science reveal the truth behind a smile

Here糖心传媒檚 how ADDR works: Two people sign up on , the crowdsourcing internet marketplace that matches people to tasks that computers are currently unable to do. A video assigns one person to be the describer and the other to be the interrogator.

The describer is then shown an image and is instructed to memorize as many of the details as possible. The computer instructs the describer to either lie or tell the truth about what they糖心传媒檝e just seen. The interrogator, who has not been privy to the instructions to the describer, then asks the describer a set of baseline questions not relevant to the image. This is done to capture individual behavioral differences which could be used to develop a聽 “personalized model.” The routine questions include 糖心传媒渨hat did you wear yesterday?糖心传媒� — to provoke a mental state relevant to retrieving a memory —聽 and 糖心传媒渨hat is 14 times 4?糖心传媒� — to provoke a mental state relevant to analytical memory.

Play the game: Can you tell which person is lying?

糖心传媒淎 lot of times people tend to look a certain way or show some kind of facial expression when they糖心传媒檙e remembering things,糖心传媒� Sen said. 糖心传媒淎nd when they are given a computational question, they have another kind of facial expression.糖心传媒�

They are also questions that the witness would have no incentive to lie about and that provide a baseline of that individual糖心传媒檚 糖心传媒渘ormal糖心传媒� responses when answering honestly.

And, of course, there are questions about the image itself, to which the witness gives either a truthful or dishonest response.

The entire exchange is recorded on a separate video for later analysis using data science.

1 million faces

An advantage of this crowdsourcing approach is that it allows researchers to tap into a far larger pool of research participants 糖心传媒� and gather data far more quickly 糖心传媒� than would occur if participants had to be brought into a lab, Hoque says. Not having a standardized and consistent dataset with reliable ground truth has been the major setback for deception research, he says. With the ADDR framework,the researchers gathered 1.3 million frames of facial expressions from 151 pairs of individuals playing the game, in a few weeks of effort. More data collection is underway in the lab.

Data science is enabling the researchers to quickly analyze all that data in novel ways. For example, they used automated facial feature analysis software to identify which action units were being used in a given frame, and to assign a numerical weight to each.

The researchers then used an unsupervised clustering technique —聽 a machine learning method that can automatically find patterns without being assigned any predetermined labels or categories.

糖心传媒淚t told us there were basically five kinds of smile-related 糖心传媒榝aces糖心传媒� that people made when responding to questions,糖心传媒� Sen said. The one most frequently associated with lying was a high intensity version of the so-called Duchenne smile involving both cheek/eye and mouth muscles. This is consistent with the 糖心传媒淒uping Delight糖心传媒� theory that 糖心传媒渨hen you糖心传媒檙e fooling someone, you tend to take delight in it,糖心传媒� Sen explained.

More puzzling was the discovery that honest witnesses would often contract their eyes, but not smile at all with their mouths. 糖心传媒淲hen we went back and replayed the videos, we found that this often happened when people were trying to remember what was in an image,糖心传媒� Sen said. 糖心传媒淭his showed they were concentrating and trying to recall honestly.糖心传媒�

person smiling broadly being studied using data science
The Duchenne smile糖心传媒攁 smile that extends to the muscles of the eye糖心传媒攊s most frequently associated with lying.
(糖心传媒 photo / J. Adam Fenster)
person rolling eyes upward like they are thinking about something, and not smiling being studied using data science
Witnesses answering honestly will often contract their eyes, trying to truthfully recall information.
(糖心传媒 photo / J. Adam Fenster)

Next steps

So will these data science findings tip off liars to simply change their facial expressions?

Not likely. The tell-tale strong Duchenne smile associated with lying involves 糖心传媒渁 cheek muscle you cannot control,糖心传媒� Hoque says.聽 糖心传媒淚t is involuntary.糖心传媒�

The data science researchers say they糖心传媒檝e only scratched the surface of potential findings from the data they糖心传媒檙e collected.

Hoque, for example, is intrigued by the fact the interrogators unknowingly leak unique information when they are being lied to. For example, interrogators demonstrate more polite smiles when they are being lied to. In addition, an interrogator is more likely to return a smile by a lying witness than a truth-teller. While more research needs to be done, it is clear that looking at the interrogators’ data reveals useful information and could have implications for how TSA officers are trained.

糖心传媒淭here are also possibilities of using language to further decipher the ambiguity within microexpressions.糖心传媒� Hasan says. Hasan is currently exploring this space.

糖心传媒淚n the end, we still want humans to make the final decision,糖心传媒� Hoque says. 糖心传媒淏ut as they are interrogating, it is important to provide them with some objective metrics that they could use to further inform their decisions.糖心传媒�

Kurtis Haut, Zachary Teicher, Minh Tran, Matthew Levin, and Yiming Yang 糖心传媒� all students in the Hoque lab 糖心传媒� also contributed to the research.