Lying and the Theory of Mind: A Newfound Ability in Preschoolers

"Johnny, did you just take a cookie after I told you not to?"


When you find out that your child has lied to you, it can be pretty distressing. Your sweet, innocent child chose to deceive you, which could only mean that they are now headed down a road full of deceitfulness, bad choices, and possibly crime. Well, not necessarily. Before you start drawing conclusions and panicking, it's helpful to take a step back and to try to understand where your child is coming from.

Acquiring the ability to lie, oddly enough, demonstrates progression in a child's cognitive development through a newfound mental awareness that he is an individual who is separate from the rest of the world, and that he and others have their own thoughts, beliefs, values, emotions, and intentions. This realization is known as "theory of mind" in psychology.

Theory of mind is an extremely important milestone because it helps children build their social skills by allowing them to more accurately anticipate, judge, and understand the contents of people's minds. Consequently, this skill also helps children appropriately communicate and interact with different individuals in varying circumstances throughout life.

While theory of mind can develop at different times for different children, it is around the age of four when most children have developed an understanding that "daddy and mommy don't know everything I know". One way to gauge if a child has a theory of mind or not is to use a test researchers have utilized in the past called the "Sally-Anne Task", which is demonstrated in this video.

Younger children have shown their ability to understand this principle of theory of mind as well, in a limited capacity. It has been discovered that children who are 18-months old and older are able to discern between foods an individual likes and dislikes based off of their facial expressions, and then can then correctly give the individual the foods they like, even if the child doesn't like this food herself. Click here for a video illustration of this ability in children 18 months and older.

While having a theory of mind can allow your child to exhibit positive behaviors and attitudes, such as showing empathy and sympathy for others, it can be unsettling when your child uses his theory of mind for reasons that you do not agree with, such as lying.

So, what are some positive ways we as parents can help our children understand lying is not okay, and to teach them the value of honesty?

  • Read a story or watch an age-appropriate video about lying, or tell your child an appropriate example of when you told a lie and focus on the negative consequences of telling that lie in words your child can understand so she won't want to lie (use examples of emotions, e.g. "I felt guilty and sad when I lied because it hurt his feelings",etc.)
  • Similarly as the previous example, tell an account of when you were honest, and focus on the positive consequences of telling the truth (use examples of emotions, e.g. "I was happy I told the truth because it made made my friend happy", etc.)

For more ways on teaching your child honesty and the value of telling the truth, click here.

For examples when lying is or is not a problem, click here

So, in the end, while lying is something we do not agree with, its development in our children represents a greater understanding of the difference between their and others' individual minds. This knowledge can contribute to better communication and to relating more to others as they can empathize with others as they grow and develop. Overall, I'd say the benefits of learning the theory of mind outweigh the costs of learning to lie.


Levine, L.E., & Munsch, J. (2014). Child development: An active learning approach (2nd ed.).Thousand Oaks, CA: SAGE Publications, Inc.

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Friday, 19 August 2022

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