Deceptive, dishonest, double-dealing, duplicitous kids

Kids lie. Often parents don’t want them to, but they do it anyway. And the thing is, lying works. If it didn’t, there’d be no point in trying. In fact, it’s notoriously difficult to detect when people are lying, at least based on non-verbal cues, like “looking away.” Even professionals like police officers only figure out who is lying and who is telling the truth in controlled experiments using high-stakes lies around 70% of the time.  

To date, research suggests that most kids lie from 3 years. The most used experimental task involves asking children not to peek at something desirable. For instance, the experimenter might conceal a toy under a piece of cloth, or hide it behind the child’s back, and then ask them not to look while the experimenter leaves the room. Most kids just can’t help but look, so when the experimenter comes back to the room and asks them if they peeked, the child has to decide whether to lie or fess up. And most of them lie, denying they looked at the hidden object. You can check out this video to see it in action.

While kids’ lying might not seem ideal to parents, good lying can highlight advances in cognitive and social development. In a recent study by Tracy Alloway and myself, we found that 6- and 7-year-olds with better verbal working memory were also better at covering up their lies. In our study, children could win a prize if they got three questions right. Each question was on a card, with the answer on the back (as well as an unrelated picture, like a car). The first two questions were easy, e.g., “What colour is a banana?” However the third question was a trick question, asking children the name of the boy in the cartoon Space Boy. The problem is, there is no such cartoon. So when we gave them the four possible answers (Jim, Ben, Lee, or Tom) there was no way they could be sure to get it right- unless they peeked at the back of the card. As it happened, the experimenter needed to leave the room at this moment, and asked the children not to peek. A hidden camera recorded whether they peeked or not. When the experimenter returned, she asked kids if they peeked to establish if they would lie. She also asked some follow-up questions to see if they could cover up their lie.  In particular, there was a picture of a monkey on the back of the card, alongside the answer. The experimenter asked each child what picture could be on the back of the card. The bad liars would blurt out “monkey”, revealing they’d peeked since that would be a very lucky guess. The good liars would say something else, e.g., “boat.” All the kids also participated on a verbal working memory test where they had to remember more and more random letters in a row (e.g., LPBS). It turned out that the kids who could remember more letters were also the good liars. This makes sense because when you’re covering up your lie, you not only have to remember all the true information, but also all the fake information, which is a lot to juggle.

Kids become better liars to protect themselves in social situations as well. Victoria Talwar found that children who face corporal punishment at school (e.g., being hit) were better at covering up their lies than children who go to schools where corporal punishment is not used. This makes sense – when the stakes are high, children come up with ways to avoid being physically hurt. Children therefore adapt and learn sophisticated social interactions to have the best outcomes.

While most children lie, at least from 3 years, and while this shows sophisticated social adaptation and cognitive development, a lot of parents might still be more concerned with the moral aspects. Is it morally ok to lie? This might be better answered by philosophy, and many philosophers have tried to figure this out. The traditional perspective suggests that all lies are wrong, no matter what, in part because it make communication unreliable. Kant went as far as to say that if a murderer asks you where their next victim is, it is more immoral to lie than to tell the truth. In contrast, the utilitarian perspective suggests that lying is ok if it’s for prosocial reasons. For instance, imagine someone asks you if they look nice in a dress, and you say they do, even if they don’t. This would be a lie, but it would serve to spare someone’s feelings. Therefore utilitarians would suggest it is moral because it decreases pain and increases happiness. There probably isn’t an easy answer to which view is right. I ask my students every year if they are traditionalists or utilitarians, and I always get both types.

While recent research has started to show us about how lying works in kids over 3 years, we know very little about lying in children under 3. That's why we are running the Early Deception Survey this month, for anyone with a child between 0 and 47 months. We want to hear from you whether or not your child understands deception yet, whatever country you are from, and whatever your child's type of development (e.g., typical, Down's syndrome, deaf, etc.) When lots of parents fill out lots of surveys, we can start to piece together when and why children develop their ability to deceive. Just register or login on our homepage at

· Dr Elena Hoicka is a Lecturer (equivalent to Assistant Professor) in developmental psychology at the University of Sheffield, in England. Her research focuses on the early development of humour, pretending, deception, and learning.


Alloway, T. P., McCallum, F., Alloway, R. G., & Hoicka, E. (2015). Liar, liar, working memory on fire: investigating the role of working memory in childhood verbal deception. Journal of Experimental Child Psychology137, 30-38.

Bond Jr, C. F., Omar, A., Mahmoud, A., & Bonser, R. N. (1990). Lie detection across cultures. Journal of Nonverbal Behavior14(3), 189-204.

Kant, I. (1949). On a supposed right to lie from altruistic motives. Critical of practical reason and other writings, 346-350.

Polak, A., & Harris, P. L. (1999). Deception by young children following noncompliance. Developmental Psychology35(2), 561.

Talwar, V., & Lee, K. (2011). A punitive environment fosters children’s dishonesty: A natural experiment. Child Development82(6), 1751-1758.

Vrij, A., Mann, S., Robbins, E., & Robinson, M. (2006). Police officers ability to detect deception in high stakes situations and in repeated lie detection tests. Applied Cognitive Psychology20(6), 741-755.