If you hadn’t heard, polygraph tests (so-called “lie-detector tests”) are not very reliable. While they still have their defenders, many courts won’t except the results as evidence. A polygraph can’t tell if you’re lying; it can only tell if you’re nervous.
But surely, with evolving technology and smart people working on the subject, we can do better than polygraph tests? Micro-expressions? Brain waves? Artificial intelligence?
A recent publication took a look at all the currently popular methods of lie detection and concluded, “the science shows that there are no reliable behavioral signs of deceit that humans are able to detect.”
Most of these methods perform no better than guesses. Even those that do better than guesses aren’t ready for use when the stakes are high.
The stakes are often high when someone could be lying. Imagine how much easier the criminal justice field would be if law enforcement, judges and juries could reliably tell who was lying.
A psychology professor summarized the publication’s findings in this article in Psychology Today. We recommend reading it if the subject of lie detection piques your interest. We will offer just brief highlights.
No, body language and micro-expressions don’t reveal lies
Despite their popularity on the TV show “Lie to Me,” people’s body language and micro-expressions do not reliably reveal lying, even to trained experts, according to the article. Nevertheless, law enforcement agencies and governments continue to spend millions funding this research.
Similarly, there was no evidence that MRI machines could detect involuntary movements or brain waves that indicated lying.
One small study found a specific interview technique could be effective. It involves asking the person to tell their story fully. Then, the interviewer confronts them with any independent evidence that is inconsistent with their story and asks them to account for the discrepancy. The study found that liars respond differently from truth tellers. This is a technique used in cross-examination, but it might not be very useful early in an investigation when catching a lie could be most impactful.
And, artificial intelligence has not created any magic, either. A recent study did find that AI could identify liars more often than humans did based on the same material. Nevertheless, the AI’s accuracy was only around 69% in lab conditions. It could be even less reliable in real-world conditions.
There’s no magic method to help us perceive lies
This isn’t to say you shouldn’t trust your instincts – or ignore solid evidence of a lie. However, it’s crucial to know that, as a species, we’re not very good at recognizing lying. There are no experts who can reliably recognize lying, even with emerging technology.