While certain people might seem like they’re better at lying than others, it turns out that anyone can train themselves to fib. Researchers at Northwestern University found that 20 minutes of practicing makes telling lies as easy as telling the truth.
In a small study of 32 people, researchers asked half of the participants to remember three facts about a false identity: a new name, date of birth, and hometown. Researchers then asked volunteers to answer the question “Is this true of you?” for different facts and to press a “yes” or “no” button in response. The people with a false identity were asked to practice lying by selecting “yes” for the new facts. Researchers measured response time and accuracy and, after 270 trials, or 20 minutes of practice, the liars’ values matched those of the truth-tellers.
Why does it take training to become skilled at telling a lie? Because lying requires some mental juggling, says Xiaoqing Hu, a study co-author and psychology doctoral candidate at Northwestern University. When you tell a lie, you have to hold two conflicting answers in mind and suppress the one that’s true. However, 20 minutes is enough time to memorize the lie completely, which means no extra thought is needed to tell it. Plus, psychologically, it’s possible that after repeating something to yourself over and over again, you can subconsciously convince yourself that it’s true, even when you (logically) know it isn’t.
“The way our minds work can be quite flexible,” Hu says. “We can be very good at ‘deceiving’ ourselves to be better. For instance, if I told myself repeatedly ‘I am competent, I am smart, I am good at math,’ then such self-initiated ‘training’ might also help one’s real performance,” he says. “This could be similar to the self-fulfilling prophecy, but with training.”
Unfortunately, not all lies are so positive. In the absence of a polygraph test or hard evidence, here are three ways to tell if someone is lying to you—and a few “tells” that just aren’t effective.
Someone might be lying to you if…
It takes them too long to respond
If someone takes a long time to respond to a simple question, then you should find it suspicious. But there’s no cutoff for too long—it’s relative. In his research, Hu compares response times between two types of questions of similar complexity: ones that he knows people will respond to truthfully and ones that they might respond to deceptively. If replies to the second type of question take much longer than the first, then the answers could be lies. So if you ask someone to tell you their favorite color and the year they were born, their response times should be about the same.
Their pupils get bigger
Pupil dilation is a reliable indicator of lying since enlarged pupils are a sign that your brain is working hard—which it has to do in order for you to tell a lie. If you see someone’s pupils get bigger as they answer a question, it could be a sign that they’re making it up as they go along (or trying to remember the original lie, and stick to the script).
What they tell you doesn’t make sense or isn’t fleshed out
Your radar should go up if you can’t follow their story or if it has fewer visual and auditory details than something else they told you which you know is true, Hu says. If your friend usually tells you everything she saw, heard, or said as it pertains to other stories, but she can’t tell you the name of the bar where she partied with Ryan Lochte, you should be dubious.
That said, certain common “tells” aren’t tells at all. You may have heard that these signs are signals that your friend is lying to you…but they don’t actually indicate anything.
They look up to the left
It’s been widely reported that looking up to the right while talking is a sign of recall (the left brain is for logic and memory), while looking to the left shows access to the right brain, or the creativity center, which means that the person is concocting a lie. But this was proven to be ineffective, Hu says. In fact, he says, “what people say matters more than what they do while they’re saying it.” So if someone crosses their arms, scratches their nose, or doesn’t look you in the eye, it doesn’t automatically mean they’re lying.
They make a funny face or force a half smile
Facial expressions may matter in some lies, but not in others. “We usually think facial expressions are connected to emotional responses, but people may vary considerably regarding emotional responses when they tell lies,” Hu says. Maybe the person you’re talking to tends only to give short smiles, not full-faced grins.
Their demeanor shifts
If someone suddenly gets uncomfortable or angry, it’s is usually a sign of nervousness and that could happen during both lying and telling the truth, Hu says.