The equipment we use for measuring eye movements (the Tobii eye-tracker) consists of a computer screen with a built-in camera that takes pictures of your child’s eyes. Your child will sit on your lap and watch a short movie on the computer screen.
While your child is watching the movie, we record his or her eye movements and later investigate whether and how he or she followed what happened on the screen and which aspects he or she paid most attention to.
Before the measurement can begin, your child will see a circle moving to different positions on the screen. In this first phase of the experiment it’s important that your child looks at the circles and doesn’t move around too much. In this way, the computer can register what your child’s eyes look like when he or she looks at different parts of the screen. This usually takes just one or two minutes. The main experiment then starts, during which your child will watch one or two short movies. Generally, each experiment lasts only a few minutes, but if your child becomes very restless, we can simply end the experiment.
The eye-tracker allows us to learn how babies perceive and process other people’s actions. The picture below is from a study where we investigated whether babies already know what various objects are used for. The pictures show the child watching as a person picks up a cup (the child’s eye movements are shown by a blue dot.) It’s very clear that the child has anticipated what the person is going to do!
Even if we show a movie where a person does something unexpected, we can learn something about what the child is expecting to happen. Although the person in the picture below brings the cup to her ear, you can see that the child looks at her mouth! From this we can therefore conclude that this child is already aware that you generally bring a cup to your lips in order to drink.