The Shopping Cart Study investigates how toddlers develop awareness of their own bodies. Developed by Chris Moore and colleagues in 2007, the task examine when a sense of self develops in babies. At what age do children begin to understand how their bodies interact with the world?

The shopping cart task involves tying a small rug onto the back of a toy shopping cart, right by the back wheels. If you tried to push the cart, you’d be standing on the rug which would make it impossible to push the cart. In order to push the cart, you have to realize that your body standing on the rug is what’s impeding your ability to push the cart forward. In other words, you have to have enough of a sense of self to understand how your body interacts with the world.

14-15 month olds will stand on the rug and try to push the cart and have no idea why it doesn’t move forward. They get frustrated and will try strange tactics like trying to climb into the cart.

16 month olds understand that the rug plays a part in what’s blocking them from pushing the cart, but think it’s something to do with the mat, and not themselves.

18 month olds will typically try to push the cart once, and then quickly realize that they themselves are the obstacle to moving the cart. This suggests he’s aware of himself and his body.

Check out the video version of this episode on YouTube.