Skip to main content

Verified by Psychology Today

Why Your Child Lies

Children as young as two years of age lie, but do they know what they're doing?

Source: iStock

What's a parent to do?

You check in on your kids only to find colorful marker drawings all over the wall. Or the cookie jar empty. Or a vase broken. And each child looks you straight in the eye and says, "It wasn't me."

Yes, you've entered into the world of childhood lies. Now the question is what to do about it.

Before we address that question, consider first what it means to lie. Suppose three children are playing in a room. Alice looks into a box and sees a teddy bear. She wants to keep the teddy bear for herself, so she tells Bruce, who is standing across the room and can't see inside the box, "There's a Barbie doll in there." Bruce, wanting to stir up a bit of trouble for Alice, then tells Carla, "There's a Barbie doll in the box over there."

Did Alice lie? Did Bruce?

As adults, we know that Alice lied but Bruce did not. Alice knew what was in the box, and deliberately spoke a falsehood with the intention of planting a false belief in Bruce's head. Bruce spoke a falsehood that he believed to be true with the intention of planting a true belief in Carla's head.

How would children respond to these questions? It depends on the child's age. In studies that use methods like these, most children younger than about age 7 claim that both Alice and Bruce lied because what they said was contrary to fact. Most older children, however, claim (like adults) that Alice lied but Bruce didn't.

Similarly, in another study, young children watched as a "good guy" hid his treasure in a treasure chest on the beach. He left footprints in the sand leading up to the chest, and a key next to the chest. A "bad guy" was going to steal treasure. They were asked how can we prevent the "bad guy" from getting the treasure?

Younger children tried to stop the "bad guy" through sabotage by erasing the footprints and locking the chest. Older children tried to stop the "bad guy" by manipulating what he believes ("The treasure isn't there. It's in another chest over there.")

The Game of Deception

Put simply, deception occurs when one individual deliberately and successfully convinces another individual to accept as true what the first individual knows to be false.

In order to lie successfully, a person:

  • Must be able to tell the difference between what is true and what is false
  • Must know that it is possible for someone to have a false belief
  • Must be able to suppress their knowledge of the true state of affairs while communicating something contrary to fact
  • Must deliberately intend to plant a false belief

Such are the cognitive demands of deception. And they take a long time to develop in childhood.

Toddlers (ages 2 to 3 years) like to engage in pretend play such as drinking imaginary tea from toy teacups during a pretend tea party. As this ability to pretend emerges, so does the ability to deliberately make factually untrue statements ("It wasn't me").

But toddlers don't take into consideration the mental states of the listener when they tell these "white lies." That often makes it easy for adults to tell they're lying. If no one else is home, and the walls were clean just two minutes ago, it is easy for parents to tell that their child is trying to deceive them.

Things get more difficult as children reach the fourth year of life. At this stage, they do take into consideration what the other person knows and believes, and they fully appreciate that others can hold false beliefs. Parents still have a bit of an advantage, though, because children in this age range tend to lose track of what they've said and what has to be true if the story they want you to believe is true. So they may insist that their brother drew on the walls because they forgot that their brother walked into the room at the same time you did.

At around 7 to 8 years of age, parents find themselves up against "a worthy adversary." Children in this age range are able to conceal their lies by maintaining consistency between their initial lie and their follow-up statements.

Given developmental differences in the ability to "mentalize" events, it is not surprising that younger children generally don't engage in deception as frequently as older children. In one study, 2- and 3-year-old children were asked not to peek at a toy when an experimenter left the room. The majority of children (80 percent) couldn't resist and peeked at the toy.

When the experimenter returned and asked whether they had peeked at the toy, only a third of 2-year-old peekers lied, while 90 percent of children who were close to their fourth birthday lied. Too bad for them because when asked what the toy was—the one they said they didn't peek at—76 percent of the liars failed to conceal their lie by pretending to be ignorant of the toy’s identity. Busted.

Even more interesting, the higher the children scored on measures of "executive" function (ability to inhibit or control their responses), the more likely they were to lie and the more successful they were at lying. In fact, for each point increase in children’s total executive functioning score, they were more than five times more likely to lie.

This ability to deceive makes heavy demands on the brain's "executive" areas, most notably the prefrontal cortex and anterior cingulate cortex. But these areas take a long time to fully develop in childhood. In one study, 8 to 9-year-old children underwent fMRI brain scans while performing interactive games involving deception. The children were instructed to deceive a witch and to tell the truth to a girl.

Unlike adults, these 8 to 9-year-old children did not show significant activation in these regions. Instead, other regions that are associated with inhibiting responses and taking the perspective of another person were active (inferior parietal lobe and precuneus).

The researchers concluded that children younger than 10 years do not use the prefrontal regions efficiently because these areas of the brain are not yet fully mature. But at this stage, they can rely on other neural circuitry that allows them to consider what someone else might know and to inhibit the natural response to tell what they themselves know, both of which are necessary for successful deception.

A telltale sign of frontal lobe maturation is the ability to inhibit (or control) oneself. And, indeed, the ability of 3- to 8-year-olds’ to deceive and then offer a plausible story to cover up their lies is strongly predicted by their inhibitory control skills.

What Parents Should Do

So you've caught your children lying. How should you respond?

As the research described above makes clear, how you respond depends on the child's age. According to Dr. Tali Shenfield, an expert in school and child clinical psychology, very young children generally lie for self-protection, usually to deflect blame away from themselves for something they did wrong (like drawing on the walls or breaking a vase). She points out that praising them for being honest is of utmost importance. But when you catch them in a lie, telling a story often can get your point across better than punishment.

A recent study demonstrates this nicely.

Children ages 3 to 7 each played a game that required guessing the identity of a toy based on the sound it made. In the middle of the game, the experimenter left the room for a minute, instructing the child not to peek at a toy that was left on the table. As in most studies that employ this method, the majority of children couldn't resist and peeked at the toy. But this study included a new twist.

When the experimenter returned, she read the child a story, (“The Tortoise and the Hare,” “The Boy Who Cried Wolf,” “Pinocchio,” or “George Washington and the Cherry Tree.”) Afterward, the experimenter asked the child to tell the truth about whether he or she peeked at the toy. Children who heard the story about Washington getting praised for admitting he chopped down the cherry tree ("I cannot tell a lie") were three times more likely to tell the truth than the children who heard the other stories. Notice that the Wolf and Pinnochio stories emphasize the negative consequences of lying, whereas the Washington story emphasizes receiving praise for telling the truth.

Shenfield also points out that older children lie for reasons other than getting out of trouble. A common reason is to gain more control over their own lives. For example, a pre-teen may ask for permission to do something and simply be told "no" with no explanation. The child may then choose to engage in the activity anyway to prove they are "grown-up" enough to handle such privilege and responsibility. This is particularly true if they feel the activity would allow them a chance to prove their trustworthiness. They end up thinking, "Well, might as well lie. They don't trust me anyway."

Teenage lying often revolves around this same scenario, but with more serious consequences. According to Shenfield, the best response is to have a civil conversation about the consequences of lying and how communication can be more effective in the future. Coupling this conversation with clear consequences (such as taking away freedoms and allowing them to earn them back) can be highly effective. But, as Shenfield points out, it is important to remember that until children reach their late teens, they will not have fully developed the ability to foresee the consequences of their actions. That is what intelligent parenting is for.

Copyright Dr. Denise Cummins June 24, 2014

Dr. Cummins is a research psychologist, a Fellow of the Association for Psychological Science, and the author of Good Thinking: Seven Powerful Ideas That Influence the Way We Think.