i must not tell lies

The Scientific Way To Measure A Child’s Dishonesty

For decades, scientists have been tricking kids into misbehaving and then calling them out, to create reliable laboratory tests that can separate budding grifters from honest children.

Originally Published: 
lying siblings

Honesty sure seems immeasurable. Liars lie and honest folk don’t, but, absent an unfortunate situation, it’s difficult to know whether your friends, loved ones, and children have integrity. Even when it comes to testing one’s own mettle, it’s hard to know until an opportunity to take the path of least resistance (the path more taken) presents itself. Still, scientists have been coming up with ingenious ways of measuring dishonesty and deception since the dawn of developmental psychology. Charles Darwin explored whether infants are capable of lying in 1877 and we now know that even three-year-olds are capable of lying in laboratory settings, which, minus the laboratory setting, is a sign of cognitive development. We know all of this because scientists have spent the past 100 years perfecting the art of detecting lies.

Here’s how they do it.

How Scientists Are Tempting Kids To Lie

The most common method used to study how and why children lie is known was developed in 1965 and is known as the Temptation Resistance Program. In these programs, children are given a concealed object or toy and instructed not to peek at it when the researchers leave the room. After the hapless children inevitably peek, the researchers return and ask whether they broke the rules. “The advantage of this paradigm is that it elicits spontaneous lies from children to conceal a transgression,” Victoria Talwar of McGill University wrote of the method in a 2008 study on the subject. “More importantly, it mimics the naturalistic conditions in which children tend to lie.”

One classic 1989 study involving the temptation resistance method found that almost all three-year-olds peek at a toy when told not to, but only 38 percent lie about it when confronted by an adult. Subsequent studies have found that, as children mature, they fail the test more often. The majority of children between the ages of 4 and 7 will lie about peeking at a toy.

To test your own kid—because hey, that’s ethical—simply put a gift in a bag and hand the package to your poor tyke. Instruct your kid not to look inside the bag, and then leave him or her alone in front of a baby monitor. Keep tabs on your kid’s activity, and when they peek (they almost all crack eventually) pop back into the room and ask if your child obeyed.

Don’t yell at them. They lied and you were manipulative. You’re the bad guy (but a better informed bad guy, which is something).

…And To Deceive Researchers

When researchers want to measure deception and craftiness in kids, bigger guns are necessary. Enter Deception Tasks, which involve convincing children to cheat at guessing games. The most common incarnation is the whimsically named Hide-and-Seek Deception task. Children first play a basic guessing game with an adult—the adult hides a candy in one of two cups and then asks the child to guess where the candy is hidden. The rules are simple. Every time the child wins a round, they keep the candy. Every time the child loses, the adult keeps the candy. Then, the tables turn. The child is given control over the cups, and promised a superior prize if they can win 10 candies. After the child mixes the cups thoroughly, the adult asks the child to be honest and tell where they hid the candy.

It’s a clever experiment, because the child is incentivized to lie not just to cover-up wrongdoing, but to get ahead. One version of the test pioneered in 2002 went one step further and combined a deception task with a temptation task. Researchers hid a toy duck that made a quacking noise under a cloth, and rewarded children for correctly guessing which toy they were hiding. After the children had won a few times with different toys and noises, the researchers placed an animal toy under a cloth and then left the room, asking the children not to peek. Those who peeked and, when confronted, lied about their peeking behavior failed both the deception task and the temptation resistance task. And, presumably, made their parents look pretty bad.

The most unkind version of the deception test involves stuffing small objects under a cup, so that if the cup is turned upright it will spill its contents, and then telling children not to lift the cup while they’re gone. When they open Pandora’s Box, the evidence ends up all over the floor. That’s when the researchers come back into the room. Kids who want to lie in this scenario are forced to come up with wild reasons why the cup spilled and it’s totally not their fault. Studies suggest that children as young as 4 are able to tell strategic lies to cover up their misbehavior.

What About Kids Who Lie for the Right Reasons?

Scientists have also developed methods for measuring prosocial lying—determining whether a child only utters falsehood when the truth could hurt someone else’s feelings. There are essentially two versions of this test in the literature, and both are easy to replicate at home. The first, and most hands-off approach, is called the Moral Story Procedure. Children are told stories about characters who receive unwanted gifts, who then either admit to hating the gifts or lie and say they love the gifts. The children are then asked to rate each character as “good” or “bad”. Children who rate prosocial liars as good are generally assumed to tolerate prosocial lying.

The more exciting version of the test involves actually giving kids gifts that they’ll hate and waiting to see how they react. After pilot studies confirmed that kids do not consider blank flash cards and pencils fun gifts, one team of researchers promised children awesome prizes for completing mundane tasks, only to reward them with drab stationary. The children were all disappointed. Then, just to rub salt in their wounds, the researchers asked each child “Don’t you like your prize?”. The children who confirmed that they just love pencils and blank flash cards were taken to another room where a familiar adult asked if they really liked the gifts, or if they were just being nice. Those who fessed up were labeled prosocial liars, and then sent back to the original researchers, who asked why they had lied to them. It’s the stuff of nightmares.

Interestingly, when these kids were up against a wall they confessed to not necessarily lying for prosocial reasons. Sure, some said they lied to be polite or not hurt anyone’s feelings. But others admitted that they had lied because they were afraid of punishment.

What If I’m Raising a Liar?

Outside of controlled laboratory conditions, Fatherly does not recommend parents try any of these tests at home. Besides the fact that about half of them seem like the sort of thing that could scar a kid for life, without careful controls they are unlikely to yield meaningful results. Besides, when toddlers and preschoolers lie, it’s often harmless testing of boundaries. Even when older kids lie, it’s seldom a sign of serious problems, and more often a rite of passage.

But if you do suspect that your child is falling into a cycle of deception, it is worth discussing your concerns with a pediatrician. Instead of, you know, spying on them with a baby monitor.

This article was originally published on