Werker – newborn language abilities

It’s really fun to work with newborn infants. And to try to figure out what they know and don’t know about language, or what kinds of biases and preferences they have. And researchers who work with newborn infants take advantage of the repertoire of behaviors that a newborn infant has. In my lab, we take advantage of the sucking reflex. So when they’re born, newborn infants have a reflex to suck. You put your finger in a baby’s mouth and they’ll start sucking on it. Many babies are born with a blister from sucking their thumbs in utero. So the sucking reflex is something that’s very well developed. And you can change the properties of the sucking reflex by presenting infants with stimuli, sounds or sights that they find interesting. So if you make it that every time a baby gives a strong suck for them that they get to hear a sound, they will change the number of strong sucks that they give per minute. They will give more strong sucks so they can hear more sounds.      

You can condition the burst interval in sucking. Babies suck in bursts. They go (sucking sound) and so the strength of the suck, the duration of the suck, and burst, and the interval between bursts; all of those babies will change in order to see or hear interesting stimuli. And so, in my lab, when we test newborn infants on their preferences for different properties of language or on their ability to discriminate one type of sound from another, we use high amplitude sucking. So we present babies with a sound every time they do what is a strong suck for them, a high amplitude suck, and over the course of several minutes they suck quite vigorously to hear sounds. And they will suck more vigorously to sounds that they prefer over sounds that they don’t like. So we can count the number of high amplitude sucks per minute to the native language versus an unfamiliar language, for example, or to speech versus non-speech, and newborn babies will show us what their preferences are by the number of times that they choose to suck in order to hear those sounds.