Lie-detection model on Trump

Sophie van der Zee
Erasmus School of Economics

How often did Trump lie in his tweets? Can we objectively assess this? If so, how? Sophie van der Zee, Assistant Professor of Applied Economics at Erasmus School of Economics answers these questions in Dr. Kelder & Co at NPO Radio 1 (1 April 2023).

Van der Zee notes that everybody lies a lot. In her research she found that people think they lie only twice a day, while in experiments it turns out people lie twice every 10 minutes.

What is lying?

Contrary to what most people think, lying occurs mainly in face-to-face conversations. The Assistant Professor explains several traits people show when they are lying: a raised chin, being nervous and tense, pressing their lips and a high level of details on peripherals. Surprisingly, not looking people in the eyes is not a sign of lying.

The Assistant Professor explains that lying often does not have direct effects on behaviour, but indirect effects. For example, lying is often perceived as more difficult than telling the truth, this can cause emotions such as stress, guilt, and shame. The tricky part is that these feelings can also be caused by other factors than lying behaviour.

Study with Washington Post on Trump’s tweets

Van der Zee collaborated with the Washington Post investigative editorial to investigate lies spread by Trump. The Washington Post systematically factchecked all of Trump’s tweets. This led to more than 35,000 factually incorrect statements during his presidency. Thanks to this elaborative data set, van der Zee was able to construct a personalized lie-detection model. Specifically, the Assistant Professor did this by assessing Trump’s use of language when he was lying versus when he was not lying. She found that there were such discrepancies between factually correct and factually incorrect tweets that van der Zee can say with reasonable certainty that Trump knew (at least in part) that his factually incorrect tweets were untrue.

How bad is lying?

Lying can work as a social smoother, for when individuals want to make social connections or be liked. However, van der Zee warns that once people find out about the lying behaviour of someone, this often has devastating consequences for the connection and trust between them.

Assistant professor
More information

For the full item by NPO Radio 1, 1 April 2023, click here.

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