Research Methods We Use

One important part of language knowledge is forming categories of sounds. For example, every time you say the sound /b/ as in "bat", you say it a little differently. Infants need to know that all those different versions of /b/ are the same sound, and different from other sounds like /p/ as in "pat". It is also important that infants can hear the difference ("discriminate") between the /b/ sound and the /p/ sound. In order to test infants' discrimination and categorization of different sounds and melodic patterns in speech, we use a procedure known as "habituation". In this procedure, infants hear a series of sounds, words or phrases repeated many times, whenever they look toward a computer monitor. Eventually, the infant becomes bored with the sounds and starts to look less at less at the screen in order to hear the sounds. When this happens, the testing begins. Infants will then hear new sounds, some of which are the same as, or same category as, the sounds they have been hearing. Others are a different sound or sound category. By measuring how interested they are in the new sounds by how much they look toward the monitor, we can learn whether infants discriminate these sounds or sound categories.