Lies are hard to detect, and you're probably worse at catching them than you think. Psychologically speaking, lies are like needles in haystacks. Human communication relies on cooperation, so most of the things people tell you have to be true most of the time—probably more than you realize.
We're verbally inundated with more information than we pause to notice and instead take much of it at face value, which we're right to do more often than not. If that weren't the case, it would be hard even to get a simple conversation started, let alone accomplish any goals you want to achieve. That's one reason why con artists are so effective. The "con" stands for "confidence," after all; they succeed by telling lots of truths in order to get away with one big lie.
In other words, it's hard to be skeptical of liars all the time. If you had to constantly monitor everything people tell you on the off chance that something might be untrue, you'd waste a lot of time and would struggle to build relationships. So instead, most of us generally assume that the things people tell us are true.
What's more, in many cases, the stakes for being wrong about whether someone's lying aren't actually that dire. If someone says that they like your new outfit, and they really don’t like it that much, there isn’t much of a downside to believing them anyway. Of course, some cases are consequential. Bernie Madoff, the notorious former stockbroker jailed in 2009, lied to his investors for decades in order to defraud them of huge sums of money through a Ponzi scheme.
So if you're in a high-stakes situation, it makes sense to try and be more vigilant about whether you're hearing the truth. But even then, many of us look for the wrong signals. In fact, researchers have found that when we consciously try to catch someone in a lie, we get much worse at it. Our unconscious lie-detection instincts are more reliable than our conscious ones.
Some of that may be because the common advice for catching someone in a lie simply isn't very good. You might've heard, for instance, that liars supposedly can't make eye contact when they're fibbing—or even that they make too much eye contact to compensate. Movies and cop shows on TV like to toy with the idea that liars have a "tell"; maybe someone looks up and to the left when they're lying, or scratches their eyebrow.
But while it may be true that trying to lie effectively increases the risk that we'll fall into nervous tics that give us away, most of these "cues" are simply related to stress. And we can feel stress for all kinds of reasons—not just because we know we're lying. Maybe the person you're talking to might be excited about a big deal being negotiated, or they might just find social interactions difficult.
Whatever the case, if someone feels uncomfortable while talking to you, they might have trouble making eye contact or overcompensate by holding your gaze. So while those supposed "tells" maybe accurate signs of discomfort, they're often red herrings for deception.
Plus, many lies don’t come along with a stress response. You might be talking with a very well-practiced liar. They might have convinced themselves that the lie is important—and may even have started believing it themselves. Or they might just not think the lie is a big deal, even if you think it is.
So if you're really concerned that someone might be lying to you, the best thing you can do is to keep talking to people. Studies suggest that the best way to detect liars is to focus on knowledge rather than on signs of stress.
That is, if you're telling the truth about something you did, there's a lot of information you have about the situation that you probably haven’t thought about. If you went to a particular conference talk, for instance, you probably know what floor of the hotel it was on, the size of the room, and how full it was. If you actually know a particular person, then you probably know whether she wears glasses, whether she favors dresses or slacks, and whether she's prone to use foul language in private conversations.
When you have concerns that someone might be lying to you in an important situation, the best thing you can do is engage them in a longer conversation. Ask lots of questions about factual information that you could go back and look into later. Liars often stumble on these questions because they didn't expect to be asked about that information. Even if they answer fluently, they're likely to make up an answer that isn't true. If the situation is important enough, you can verify what they said before deciding for certain whether the person is telling the truth.
Typically though, we don't think to probe this deep. Instead, we try and detect subtle behavioral signals when we're on guard against lies—and those lead us astray. That makes sense: We don't want to interrogate the people around us, which might make us look nosy or paranoid.
But more often than not, this fear is unfounded. People should expect you to ask a lot of questions about something you care about—that's how they'll know you care. Not only can that put liars on notice, it can also help you gather the information you'll need to actually sniff them out when it matters most.