The average person lies once or twice per day. Some lies seem innocuous, like telling your wife she looks good in that outfit. Others are meant to deceive, such as hiding an affair. The question everyone has to ask is which lies, if any, are acceptable and which are not.

Some lies serve as social lubricant. When you tell a friend that you can’t make it to your party because you already have plans, then that can elicit less negative consequences than telling the friend they have boring parties. Sometimes you tell the waitress that everything is fine, even though your steak tastes like a shoe.

These little white lies are particularly common in romantic relationships, occurring in one out of every 3 conversations. The number goes down to one-in-ten when you get married. There is a fine line between sparing a person’s feelings and manipulation, however. Telling your wife she looks like she lost weight can be a set up for asking a favor. When the lie is self-serving, you may be simply justifying it by claiming empathy.

Men and women lie equally, but about different things. Women are more likely to lie to spare a person’s feelings. Men, however, are more prone to lying about themselves. Think of the guy at the bar who is a world renowned cosmopolitan who can bench press twice his weight. Chances are there is a hint of exaggeration in the story.

People lie a lot. On average, they lie in one out of five social exchanges lasting more than 10 minutes. They deceive about 30% of the people they interact with one-on-one with in a given week. There is good reason for this. One 1999 University of Massachusetts study found that the most popular kids are also the most effective liars. Society rewards deception. Think of the consequences of calling in hung-over rather than sick.

Despite the prevalence of lies, most people are not very good at picking up liars. Polygraph machines err between 25% and 75% of the time. This is because they measure fear, not the lie itself, and also why they are not admitted as evidence in most state and federal courts. The main question to ask when you are wondering if a person is lying is, “What is their motive?” If a person is being evasive, changing their speech patterns, or gesturing in a strange way it can be a sign of a lie. You need to first establish a baseline, however, to determine what constitutes a deviation from that person’s version of normal.

Additional Resources

Psychology Today, Deception: http://www.psychologytoday.com/basics/deception

Santa Clara University, Lying: http://www.scu.edu/ethics/publications/iie/v6n1/lying.html

U.S. News, How Lying Affects Your Health: http://health.usnews.com/health-news/articles/2012/08/20/how-lying-affects-your-health

BBC, Lying: http://www.bbc.co.uk/ethics/lying/lying_1.shtml

Eyes for Lies: http://www.eyesforlies.com/