Here’s how an AI lie detector can tell when you’re fibbing


Artificial intelligence is everywhere—it figures out what’s in the food photos on sites like Yelp, it helps researchers attempt to make MRI scans faster, and it can even look for signs of depression in someone’s voice. But here’s a use you may not have considered: lie detection.

That idea—an AI fib sniffer—is in the news because of a border security project in Europe called iBorderCtrl that involves technology focused on “deception detection.” The initiative includes a two-step process, and the lie-detection part happens at home. According to the European Commission, the protocol begins with a pre-screening in which voyagers “use a webcam to answer questions from a computer-animated border guard, personalised to the traveller’s gender, ethnicity and language. The unique approach to ‘deception detection’ analyses the micro-expressions of travellers to figure out if the interviewee is lying.”

It sounds like science fiction, and of course, it also brings to mind the troubling history of polygraph tests. But such an AI system is possible. The question is: How accurate can it be?

Rada Mihalcea, a professor of computer science and engineering at the University of Michigan, has worked on deception detection for about a decade. This is how they constructed one AI deception detector, and how it works.

The first thing that researchers working on artificial intelligence and machine learning need is data. In the case of the work that Mihalcea did, they began with videos from actual court cases. For example, a defendant speaking in a trial in which they were found guilty could provide an example of deceit; they also used testimony from witnesses as either examples of truthful or deceitful statements. (Of course, machine learning algorithms are only as good as the data fed into it, and it is important to remember that someone found guilty of a crime may in fact be innocent.)