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Have We Finally Found a Way to Detect Lies?

New research reveals why it's so difficult and how we could crack the case.

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Whether we're fact-checking the tales told by hardened criminals, the stories toddlers tell about stolen cookies, or the promises of politicians, the search for reliable ways to sniff out the “truth” usually proves to be an elusive quest. We’ve been told that everything from eye blinks to heart and breathing rates are the best routes to uncovering a liar, but so far, we have found no truly foolproof methods.

It will never be possible to dig down into the stored memory of individuals whose lies we’d like to uncover, and even then, what’s stored in memory may not be that accurate: As time separates us from our previous actions, we smooth over the rough details to make them consistent with our identities and desires. Now Berkeley neuroscientist Adrianna Jenkins and colleagues (2016) have developed what they believe is a new approach to gaining insight into the neural pathways activated when people lie.

They started with a classic paradigm used in research on honesty and deception, operating from a game theory framework known as the Comparison Question Test (CQT) or Guilty Knowledge Test (GKT), which participants complete while in a brain-scanning device. The paradigm involves having participants witness an event and then answer questions about it that only they, as witnesses, would recognize as relevant or irrelevant. If you don’t know what happened and aren’t trying to cover anything up, you won’t respond any differently to relevant and irrelevant questions. If you know what happened, and lie about it, you’d show a greater reaction to relevant questions because you’d know you need to cover up the truth.

This paradigm isn’t new—it's the basis for the (still fallible) polygraph. As reported by the Berkeley researchers, the polygraph method is flawed because telling someone to lie isn’t the same as having someone produce their own lies based on their own motivations and assessment of a situation. What’s worse, no clear patterns have yet emerged from studies of brain imaging to indicate that there’s an identifiable “lie center” in the brain.

The approach that Jenkins and her team advocate instead takes advantage of the “signaling” framework, in which people are tracked by the signals they send off when communicating with others. The signals may involve spoken language, but they can also involve gestures and facial expressions. They have no meaning in and of themselves; instead, their impact depends on the how the receiver interprets them. A “sigh,” as the song goes, “is just a sigh,” but if it’s a sigh of disgust or a sigh of pleasure depends on who hears it, and whether you and the other person have a romantic connection or are at opposite ends of a bitter dispute.

The signaling framework suggests that to study lying, you need to observe it in its natural habitat—situations in which people actually communicate to each other, both sending and receiving signals. In real life, you usually don't follow instructions to lie (as you do when setting the baseline for a polygraph test). You decide whether to lie or not based on whether it will benefit you more than it will harm the other person, and also on how you think what you say will be interpreted by the other person. Your twin sister may sniff out your fib in no time flat, but with people you hardly know, you can potentially get away with almost anything, like telling a supervisor you are thrilled with a new assignment you secretly find loathsome.

In the real-life scenarios created by the Berkeley team, senders and receivers engaged in buying and selling games. In one such scenario, the sender tries to convince the receiver to buy stock by promising that its value will rise. The receiver’s job is to decide if the sender is telling the truth. Researchers can monitor the communication in real time to measure brain activation in senders and receivers to see which areas become most engaged at different steps in the process.

Another example is the “trust game," in which you promise someone else that you’ll do something which you, in the deception condition, don’t actually do. You might agree to split the profit of a sale with your partner in half, but once you have the money in hand, pay only 30 percent. As in the bargaining paradigm, brain activation can be monitored in you and your partner while both of you are in the anticipation and action stages of this sequence.

As Jenkins and her collaborators point out, lie detection with a polygraph “constitutes a signaling game between the interrogators and the interrogated,” in which both can “game the system” by regulating their thoughts and feelings during the process. Imagine if those brain activation patterns could be compared to the patterns shown by people involved in the experimentally-controlled bargaining situations.

Thinking about signalers and receivers as participants in an interaction involving deception suggests that the entire process has a dynamic quality to it that reflects a complex array of processes taking place over time. We don’t know what all of these processes are, or how much they reflect that combination of verbal and nonverbal signals. However, this research moves the needle forward by providing suggestions for laboratory tasks that resemble the way that people interact with each other under natural conditions.

Given that most of us won’t become researchers who conduct brain imaging studies, what use does this approach have for you? The important takeaway is that it’s unrealistic to expect that simple questions will elicit the truth from people you think are lying to you. Consider that cute little toddler whose cookie-crumb-covered shirt seems to be a liar for sure. You may not realize that someone else offered the child the cookies or that the child actually didn’t know that the cookies were off-limits. Similarly, your romantic partner, whose accounts of his or her whereabouts seem sketchy to you, may have motives in mind about which you’re unaware. Or it’s possible that your partner is just responding to the way you posed the question. Even the salesperson who seems to be offering you a deal that seems too good to be true is basing his or her approach on the way you seem to be reacting.

Become a different receiver, and the signaler may change as well.

Rather than try to elicit the truth from those you interact with in an all-or-none fashion, consider the role that deception plays in communicative processes. It may not always be the most desirable way to communicate, but it may what the situation brings out in both of you.

Follow me on Twitter @swhitbo for daily updates on psychology, health, and aging. Feel free to join my Facebook group, "Fulfillment at Any Age," to discuss today's blog, or to ask further questions about this post.

Copyright Susan Krauss Whitbourne 2016


Jenkins, A. C., Zhu, L., & Hsu, M. (2016). Cognitive neuroscience of honesty and deception: A signaling framework. Current Opinion in Behavioral Sciences, 11130-137. doi:10.1016/j.cobeha.2016.09.005

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