Study Methods

Methods Used to Study Infants

Habituation/Test Procedure

Suppose that you would like to know if your baby can tell the difference between different colors (in other words, can babies see different colors?). You have the baby seated in front of a computer monitor and you show the baby a yellow patch of color. Here is a picture of a baby actually looking at such a patch.

Let us then say that you show the patch to the baby for up to 30 seconds at a time as long as the baby keeps looking at it. As soon as the baby looks away from the patch, you make it disappear and when the baby looks back at the monitor you show it again for up to 30 seconds. During each of these 30 second periods you keep track of how long the baby actually looks at the patch by watching the baby through a camera that is trained on the baby's face (the camera is not visible on the picture but would typically be placed either below or above the monitor). Whenever the baby looks at the patch you push a button that is connected to a computer that actually measures the time and records it. You keep showing this patch over and over to the baby. Each time you show it, the baby shows less and less interest in it and, thus, looks less and less. This is what we call "habituation". It actually means that the baby has learned about the properties of the patch. Now comes the critical test part of the experiment. You now show the baby a red patch. Assuming that your baby can distinguish between the two different colors, he or she will show renewed interest and look at the red patch for a longer amount of time. This increase in looking is taken as a sign that the baby has recognized the new color. That's all there is to it! You are done and now you can say that your baby can tell the difference between yellow and red. Imagine now that instead of being interested in finding out whether your baby can see different colors, you want to know whether your baby can understand different speech sounds or even tell the difference between your voice and that of a stranger. To answer this question all you have to do is repeat the experiment and substitute speech sounds or your voice and that of a stranger. It is truly that simple! In other words, the habituation/test method is so general that it can be used to study babies' perception of almost anything.

Paired-Preference Procedure

Suppose that you would like to know if a baby can tell that a particular voice belongs with a particular face. This is something that we have to be able to do whenever we find ourselves in a room-full of people. We hear someone talking and we must be able to connect it with a particular face. Only this way can we have unified perceptual experiences of the people and objects in our world. To determine whether and when in infancy a baby might be able to connect a face and a voice, we can conduct the kind of study pictured below. Imagine that the baby gets to see two different faces and that each of these faces can be seen talking. At the same time, we let the baby hear only the voice of the person on the left (who is saying "peek-a-boo"). If the baby can tell that the voice they are hearing corresponds to the face on the left then he or she will look at that face. If the baby does then this means that he or she recognized the unity of that particular face and voice.

Eye Tracking Procedure

Suppose that you would like to know what parts of a face your baby likes to look at. Developmental psychologists are interested in this question because answers to it provide another "window" into the baby's mind. Specifically, the answers to this question help us better understand (a) what parts of animate and inanimate objects babies find to be particularly salient as they interact with them in their daily life and (b) how their interests change as they grow and gain increasingly greater understanding of the world around them. Ultimately, information such as this will help professionals develop ways to promote optimal learning during early childhood and, thus, promote general cognitive development. Our eye tracking apparatus pictured here (below the computer monitor) is essentially a very sophisticated video camera that enables us to determine on an ongoing basis where the baby's pupil is centered as the baby looks at things like a talking face or a moving/sounding object. Because our eye tracking apparatus was developed especially for use with infants and young children, it is perfectly safe and easy to use with this population and at the same time has the ability to provide fascinating insights into the development of perceptual and cognitive skills in early childhood.

Methods Used to Study Children

Computer Tasks

Here, 4-year-old Tommy watches as different shapes are presented on a computer screen and is asked to detect changes in the order in which the shapes are presented.

 

 

 

 

Testing with Toys

Here is 4-year-old Adrianne playing with toys in a toy-train game designed to probe her understanding of the order of objects in a sequence.