Probability Updating

Probability Updating

Berkeley Early Learning Lab (UC Berkeley)

Who Can Participate

For children ages 24 to 28 months who reside in the US. Each participant can only participate in this study once.

What Happens

During the study, your baby will sit on your lap or a high chair and watch short movies with sounds. First, your baby will see movies of a character sorting colored candies into different bins. Once your baby has seen a lot of these videos where candies are sorted into bins based on color, we will have a second set of videos. Now, the character pulls out a candy, but does not put it into a bin. We will see which bin your baby expects the character to put the candies.

What We're Studying

This study investigates babies’ ability to use probabilistic information to make judgements. For example, if we show babies that a box has lollipops with different colored sticks and candy shapes, and the majority of those lollipops have blue sticks (regardless of candy shape), will babies expect a randomly drawn candy to have a blue stick? Then, if we reveal that the candy shape is a star, and the majority of star lollipops actually have orange sticks, do they incorporate this information and now expect the lollipop to be orange? Our study aims to explore whether babies are able to do this and update their judgements based on new probabilistic information.


15 minutes


Within a week after you participate in this study, we will email you a $5 gift card which you can redeem at To be eligible for the gift card: 1) your child must be in the age range for this study, 2) you need to submit a valid consent statement, and 3) we need to see that there is a child with you. You and your child do not need to finish the whole study to receive the gift card; however, if this is the case, please let the researchers know so that you can receive your compensation.

This study is conducted by Fei Xu (contact:

Would you like to participate in this study?