Credibility is a fraught issue these days. Playing out in one courtroom is the debacle of the discredited accuser in the Dominique Strauss-Kahn case. In another is the Casey Anthony trial with its holiday parade of potential liars. Maybe you are confident that you are a terrific lie detector -- you are sure you can separate the trustworthy from the slime. Surprise! More than a dozen studies have shown that there is no link between confidence and skill. If you think you are a great human lie detector, you are no more or less likely to actually be great than if you think you are a terrible lie detector.
In my decades of doing research on deception and studying the work of others, I've found a whole raft of ways our judgments of credibility can go astray. Here's a sampling.
- Looks can kill -- your better judgment. Some people have a certain "look" or manner about them. The lucky ones just seem honest and trustworthy all the time, even when they are lying. The less fortunate ones characteristically come across as untrustworthy, even when they are telling the truth. If you truly are a discerning lie detector, you should not be fooled by a person's characteristic look. Instead, you should be able to tell in any particular instance whether that person is lying or telling the truth. So can you? If you are an ordinary person, with no special experience or training in the detection of deception, the answer is no. Faced with a person whose typical look is inconsistent with their actual truthfulness, you are more likely to go with the look. But what if you work in a government security and intelligence agency, you have had formal training in the detection of deception and you have more than 14 years of on-the-job experience trying to detect lies? If a person's characteristic look is consistent with their truthfulness, you will be unbeatable. But if the look is inconsistent, you will do worse than college students and worse than fellow agents with far less experience. Check out the stunningly-poor accuracy scores and read more about the studies by Tim Levine, in this post.)