Originally published here by Lynn Spiro on the blog Better Ask Your Mom.


Dear Better Ask Your Mom,

I have two children, ages four and two. They quarrel from time to time, as children often do. Sometimes I’ll see my four year old daughter push her younger brother with my own two eyes, but when I intervene and ask her, “Why did you push your brother?” She will respond, “I didn’t!” Is she old enough to understand that she’s lying? I want to nip this behavior in the bud, but I don’t want to discipline her if she truly doesn’t understand what she’s saying.


Courtney M.


Mother-to-mother: Wouldn’t it be fun to be able to be inside the mind of a four-year-old for a day? Just to be a little fly on the wall in that ever-developing brain to watch all of those gears grinding? It seems like children that age have the ability to lay down some serious philosophical wisdom one minute, and the next be smearing themselves in peanut butter from head to toe. Are they secret geniuses or little goobers who are still just trying to figure out the world around them? Probably a little bit of both. Here is a little anecdote from my childhood: I was four and a half years old, and the stone from my mother’s wedding ring had fallen out. She had the ring and the stone on the counter ready and waiting to go to the jeweler to have it fixed. Four-year-old me thought, “Ooh, shiny!” So I took the stone and put it in my little jewelry box. Of course pretty soon after my mother noticed that the stone was missing from the counter and (very understandably) became frantic. Seeing my mom so upset scared me, so I didn’t tell her that the stone was in my jewelry box for fear that her frantic anger would be turned onto me. I remember her asking at least ten times if I took the stone, and each time I told her no. I told her “no” not because I was a bad kid, but because I was honestly terrified of how upset she was. I pose this next question to youcompletely and utterly judgement free- has there ever been a time that you may have had a slight over reaction to something she has done wrong in the past? As adults (myself very much included), sometimes we can forget how incredibly important our demeanor and tone can be when talking to a child. If the child is frightened, or anticipating a big blow up if they admit to a wrong-doing, they may be more prone to lying.

On the developmental side of things: There is no completely foolproof way to know at this point if your daughter really knows what a lie or lying is. Typically, a child your daughter’s age is able to at the very least have a simple conversation about what a lie is, and why lying is not OK. If you choose to have this conversation with her, one point to emphasize is how lying can make people feel. It’s important to know why lying is not OK, and not that it’s just “bad” or “not OK.”

According to Bjorklund’s Children’s Thinking: Cognitive Development and Individual Differences, a developmental test you could try would be the “false belief task.” Here are the tools you will need to accomplish this (or whatever toys/stuffed animals you’d prefer to use, the only requirement is that the cup is not see-through):

Sit down with your daughter and tell her the following story using the above items:

Bunny and lamb were playing together in their house with the ball. When they were finished playing with the ball, lamb put it away under the blanket and went outside to play. While lamb was outside, bunny moved the ball under the cup. When lamb comes back inside, where will she look for the ball?

If your daughter says, “Under the cup!” it means that she is still working towards the cognitive ability to differentiate her own thoughts from another person’s thoughts. She thinks that bunny and lamb possess the exact same knowledge as one another, so whatever one knows the other must know too. In her mind, this means that lamb will have already known that bunny put the ball under the cup while  In other words, whatever your daughter knows or sees currently, she assumes everyone else knows and sees as well- which would make it hard to tell a lie. She is still working on developing perspective taking, or the ability to “put herself in someone else’s shoes.”

However, if your daughter says, “Under the blanket!” it means she understands the concept of deception, and is capable of lying. She knows that lamb will only know that she placed the ball under the blanket, therefore this is the place she will look. She has the cognitive understanding that what she knows, everyone else may not also know.

Like Better Ask Your Mom on Facebook here.

Follow Better Ask Your Mom on Twitter here.