Researchers in our laboratory employ several different techniques for examining children’s linguistic knowledge.
1) Preferential Looking (participants: 2-36 months)
The Preferential Looking Procedure involves videotaping toddler's eye movements as they watch short movies on a large screen TV. Children sit on a caregiver's lap, and the caregiver wears headphones so they do not influence the child's behavior. The movies typically last no more than 10 minutes. When the child hears a label for objects they see on the screen, they shift their gaze to the named object. For example, if the screen has a picture of a dog on the right and a baby on the left, the infant will shift their gaze to the baby when they hear the phrase "Where's the baby?" In our lab, we have been using this procedure to examine how children learn verbs and to determine the character of children’s syntactic representations.
Click here for a video example of a two-year-old participating in a study about verb learning. We present them with novel verbs to and compare what additional audio helps or hinders their learning of that verb. The corner video displays what the child sees on the television.
Click here for a video example of a two-month-old showing her preference to look at the face mouthing the sound she hears.
2) Head-turn Preference (participants: 6-20 months)
In this procedure, the infant sits face-forward on a caregiver's lap. The wall in front of the infant has a video monitor at eye-level. The walls on the sides of the infant have lights mounted at eye-level, and there are speakers beneath the lights. Soundfiles are played from the side speakers. The soundfiles start when the infant looks towards the blinking side light, and end when the infant looks away for more than two seconds. Thus, the infant essentially controls how long he or she hears the soundfiles. Differential preference for one type of soundfile over the other is used as evidence that infants can detect a difference between the types of soundfiles. In our lab, we have been using this technique to examine children’s knowledge of function words and grammatical categories in their language.
3) Habituation-Switch Procedure (participants: 6-14 months)
During the Switch-Procedure, infants are seated on their caregiver's lap facing a large TV screen. During the experiment, infants listen to different speech sounds, words or languages. At the same time, they look at a checkerboard or pictures of objects on screen. We measure their eye-movements as they look and listen. At the beginning of the experiment, infants are very interested in the speech sounds and subsequently pay attention and look at the television screen. Eventually, infants' attention decreases and they begin to look away. When infants reach this stage, we then change the speech. If infants hear the change and find it interesting, their attention is recaptured and they look back at the screen. In this way, we can see whether infants have detected or noticed the change in speech sounds, words or languages. In our lab, we have been using this technique to examine children’s knowledge of function words and grammatical categories in their language.
4) Truth-value Judgement Procedure (participants: 3-6 years)
This procedure involves two experimenters. One experimenter plays the role of a story teller and the other plays the role of a puppet. The storyteller acts out a story using various toys and props. At the end of the story, the puppet tells the child what he thinks happened in the story. The child’s job is to tell the puppet whether he is right or wrong. In our lab, we have been using this technique to examine various aspects of the acquisition of syntax and semantics.
Click to watch a video demonstrating the Truth Value Judgement Task.
"Every horse didn't jump over the fence." This is an example of an ambiguous sentence we can study using the Truth Value Judgement Task.
Meaning 1 (M1): None of the horses jumped over the fence.
Meaning 2 (M2): Some did jump and some didn't.
What do kids think? To find out, we tell stories where M1 is false
and M2 is true. Watch the second video here.
This raised a new question: Can highlighting M2 in a different kind of sentence help kids access M2 in the ambiguous sentence? Our method was to tell the same sorts of stories, but our puppet says unambiguous "Not every --" sentences. Later, after a similar story, the puppet says the ambiguous "Every horse didn't -- " sentences. Watch the next video here.