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9 Ways to Tell Who's Lying to You

A newly-developed test can give you a sense of who's honest and who isn't.

Iakov Filimonov/Shutterstock
Source: Iakov Filimonov/Shutterstock

In a perfect world, you'd be able to believe everyone. But it's not a perfect world, so you need some help. Professionals in certain fields, such as law enforcement, become trained in spotting liars, but the rest of us can still hone our detection sensors in everyday life.

Whether it's interviewing a potential hire (at home or in the office) or deciding to believe a sales pitch, we can all benefit from knowing the telltale signs of a fibber. And in dating settings, needless to say, determining whether a potential partner is being honest or not is critical to deciding on where a relationship is headed.

Psychology seems like it should be a good place to start trying to figure out how to sift the truth from the lies. If you don't have access to a polygraph, there may be some behavioral clues that can tip you off. Although the science isn't completely there yet, a recently-published test seems to have potential. University of Texas at Tyler psychologist Jacqueline Evans and her colleagues (2013) developed the Psychologically Based Credibility Assessment Tool (PBCAT), an 11-item rating scale you can readily adapt for your own purposes.

To develop the PBCAT, Evans and her team asked a sample of 46 college students (primarily female and Hispanic) to watch videos in which a student (known as the “target”) either lied or told the truth about what he or she had done on the previous Saturday night between 7 and 10 p.m. The liars and truth-tellers in the videos also were asked to describe the order of events in either a forward or backward chronology.

The rationale for the backward-time condition was that this would create more "cognitive load" (tax their mental resources) because it's harder to reconstruct events in reverse than forward order. The condition of high cognitive load is comparable to what happens when you're in a job interview or a police station, where there are high stakes attached to your telling the truth.

Lying takes more cognitive effort than being honest in general, because you have to work harder to keep your facts straight. Once you start down the pathway of lying, you not only have to remember facts, but which facts you changed, and how. Imagine if you told your partner that the shirt you just bought cost $25 when it really cost $50 (and you paid cash). Now, if someone else compliments you on the shirt and asks where you got it, you might have to come up with a false store to stay consistent with the lie about its cost (say, Old Navy, instead of Banana Republic). That shirt is now the “Old Navy” shirt and will have to be each time it comes up as a topic of conversation. You might also have to remember to cut out the tags when you get home to support the lie.

The participants in the Evans et al. study—those who rated the truth-telling of their peers—first learned to use the relatively straightforward PBCAT. Then they sat down to scrutinize the accounts of the targets and rate each video. As it turned out, participants were more accurate in detecting deception when the person in the video was telling tales in reverse chronological order. (Evans and her team needed to try their new measure out by using a control group who rated the videos without the aid of the PBCAT.)

In the second variant of this study, the researchers created a high cognitive load condition by specifically selecting videos of targets who differed according to their facility with English. Native English speakers were in the lowest cognitive load condition. Non-native speakers with high English proficiency were considered to have slightly higher cognitive load. And the highest cognitive load was deemed to exist for non-native English speakers with relatively low English proficiency. You can probably relate: If you’re speaking a language that’s not your native tongue, and you’re lying, the task will be more draining of your mental abilities than speaking a language with which you have no difficulty.

In this variant, the PBCAT once again performed well. In general, participants were better at detecting true than false statements and were best at sorting truth from fiction when the target was mentally stressed. Importantly, there was no one cue that pointed to the target’s honesty—it was the combination of ratings that jointly produced accurate judgments.

With this background, here are the 9 basic rating scales from the PBCAT that will allow you to detect when you're being told a lie:

  1. Leaves out sensory details. A liar skips many of the little flourishes that embellish stories told by honest people. These are harder to keep straight later, so he or she just leaves them out. Someone telling the truth might mention what music was playing in the background or what color the flowers on the table were. A liar will try to be as incomplete as possible on details, including time, because these are difficult to construct and then keep consistent to in later renditions of the story.
  2. Admits frequently to faulty memory. People telling the truth don’t have that much trouble remembering a true event, situation, or occurrence. They lived it, so it comes pretty easily to them. Liars, however, will give themselves the “excuse” of having a poor memory when, in reality, it’s only the lies they’re having trouble recalling.
  3. Makes spontaneous corrections. Because liars have to backtrack so much, they will heavily edit their stories: “Her name was Lily, no it was Lisa, wait, maybe it was Linda.” You don’t have to keep an exact count of how many of these occur in a person’s speech, but if they happen often enough for you to notice, the individual is probably covering something up.
  4. Keeps it short and vague. The longer, more complete, and spelled out a story is, the more likely it is to be true. Again, telling a lie or a string of lies takes more effort because it means that you have to create an entire scenario out of your head. Brevity may be “the soul of wit,” but it’s also the soul of a lie.
  5. Doesn't make sense and is full of contradictions. By now, if you’re catching on, it should be clear that a true story will hang together better than a string of lies. Returning to the case of the shirt, it’s quite likely that clothing from a more expensive store will look more expensive. If what you’re seeing doesn’t fit with what you know to be the case, it’s very likely that you’re not being told the truth.
  6. Seems to be thinking hard. If your speaker seems to be unsure or, worse, to be putting a great deal of effort into coming up with a plausible account of events, this is a clue that his or her cognitive load is mounting. Obviously, people telling the truth may have difficulty remembering past events, but especially if an event wasn’t that long ago, and was of some significance, they should not seem to be sweating over every sentence they relate. If you ask your partner how his or her last relationship ended, that person should be reasonably sure. As time goes on, a partner who's lied about that breakup will have to work even harder to keep the details consistent with other things you learn about that past relationship.
  7. Is nervous, tense, and fidgety. It takes a great liar to be able to pull off a string of falsehoods without looking at least a little anxious. (In fact, that’s one of the cues to suggest that someone might be a psychopath.) Someone telling the truth will seem relaxed—maybe not happy, but at least not especially uncomfortable, assuming the story they're telling isn’t a painful one.
  8. Makes few complaints or negative comments. This seems counterintuitive, but it makes sense that someone trying to create a good impression would want to be positive. People high in the desire to impress others try to cover up their own negative reactions so you’ll like them (and believe them).
  9. Talks unusually slowly. The speech of a truth-teller is reasonably normal, but people who are lying tend to take quite a bit longer as they self-edit, try to be consistent, and leave out negative commentaries. We hear about “fast-talking salespersons,” but rather than lying specifically, those characters may simply be trying to confuse you. Besides, a salesperson may be able to talk quickly when reciting a well-rehearsed lie, but a lying lover will probably proceed with greater caution in retelling fictional tales of his or her past.

While from one point of view, if you plan to lie, it would be helpful to know that these 9 "tells" will be your giveaways, the PBCAT is still primarily a useful tool for helping you catch liars in the act, especially if you can create conditions that force your own “target” to tell his or her story from scratch, a condition which makes it all the more likely that someone will be caught out than if they simply answer some yes-or-no questions. Sit back, take it all in, and with some practice, you’ll be on your way to becoming your very own personal lie detector.

Copyright Susan Krauss Whitbourne, Ph.D. 2014


Evans, J. R., Michael, S. W., Meissner, C. A., & Brandon, S. E. (2013). Validating a new assessment method for deception detection: Introducing a Psychologically Based Credibility Assessment Tool. Journal Of Applied Research In Memory And Cognition, 2(1), 33-41.

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