5 ways to tell when your patient is lying to you

By John Murphy, MDLinx
Published August 22, 2018

Key Takeaways

On average, people lie about 8 times a day. Can you believe it? If you did, then you just swallowed a lie. People typically average 2 lies a day, although the majority of lies are told by a minority of people. Truth is, you’re probably not very good at detecting lies. Indeed, most people are able to detect a lie only slightly better than chance (54%), according to one meta-analysis. And physicians have a “truth bias,” meaning that they expect people to tell them the truth.

For physicians, getting the truth out of patients is not just a matter of principle, it can have serious consequences. Patients who withhold the truth or tell outright lies put themselves in danger. Think you can handle the truth? Read the following 5 tips to find it out.

1. You can’t hide your lying eyes
Perhaps the most widespread belief about deceptive behavior, which is found across cultures, is that people look away when lying (gaze aversion). One survey found that 71% of people worldwide believe that liars avoid eye contact. But researchers have found that neither gaze aversion nor “shifty eyes” provides any indication that someone is lying. In fact, the opposite may be true. (See “You ain’t nothing but a hound dog,” below.)

2. You ain’t nothing but a hound dog
Have you ever come home to a torn-up couch or a missing plate of food, and your dog is hiding under the table from guilt? Some dogs (but not all) know when they’ve done something bad. They may show the canine equivalent to a human “minus face”—a lowered chin, averted eyes, and pinched brows. People who don’t often lie (truth tellers) may show the same characteristics when they lie (or even when they tell an uncomfortable truth). But liars may demonstrate the opposite aspect by raising their chins. A raised chin expresses a level of confidence or certainty, and it’s a component of a “plus face,” which also includes direct eye contact and medially raised eyebrows. When a patient puts on a “plus face,” it doesn’t necessarily mean they’re lying—but it should raise your index of suspicion.

3. If your lips are moving, then you're lyin’, lyin’, lyin’
One stereotypical physical cue that does seem to hold true: Liars sound more uncertain than truth tellers (as measured by subjective impressions). When telling a lie on the spot, liars may be slower to respond, with more pauses and briefer responses than truth tellers. Another cue: Liars may speak in a higher pitch.

4. I want a new drug
One type of liar that physicians may commonly encounter is a patient with a drug problem who’s seeking more drugs. These patients demonstrate several characteristic actions or traits you can recognize: multiple dose escalations, noncompliance with therapy despite warnings, multiple episodes of “losing” prescriptions, seeking prescriptions from multiple sources, and functional deterioration. Behaviors that patients may exhibit that are less suggestive of a drug problem (particularly in a chronic pain patient) include aggressive complaining about the need for more drugs, drug hoarding during periods of reduced symptoms, requesting specific drugs, and occasionally escalating doses on their own accord.

5. Say it isn’t so
Besides avoiding eye contact, widely held assumptions indicative of lying include other physical cues, such as fidgeting or shifting posture, covering the mouth, and excessive arm movements or hand gestures. However, none of these cues actually correlate with lying. So, what can you go on? Listen to what the patient is actually saying. In a study of experienced police interviewers, those who were good at detecting lies focused on story cues over physical cues. In another study, police officers who read only transcripts of interviews (and were therefore compelled to focus on story cues) were better at detecting lies than officers who saw the actual interviewees.

In short, if you want to get to the truth, ignore what a patient may be showing you, but listen carefully to what they’re telling you.

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