Hierarchical Noun Phrase Structure in 18-month-old English Learners

Abstract

To derive meaning from phrases, adults must recognize the hierarchical structure of phrases and understand how their structure relates to their meaning. In the phrase “I like the blue bear,” adults understand that “blue bear” is one phrase in which the adjective, “blue”, modifies the noun, “bear.” It is not the case that I like the color blue and bears, but I like a particular blue bear. This study investigates whether 18-month-olds understand this hierarchical structure of noun phrases. We use a habituation-switch paradigm in which infants are exposed to stimuli until they lose interest, and then are exposed to new stimuli. We measure infants’ interest by recording their looking times. During the habituation trials, the infants watch videos accompanied by correct descriptive sentences such as a video of a blue bear and a red background accompanied by the audio “it’s a blue bear.” During the test trials, we present half the infants with congruent video and audio combinations and the other half with incongruent combinations. An example of a video with an incongruent combination is a video of a red bear in front of a blue background with the sentence “it’s a blue bear.” By the end of the habituation trials, the infants show little interest in the stimuli, and during the test trials we measure whether the infants recover interest and increase their looking time. If 18-month-olds build hierarchical structure in noun phrases, they will show increased interest in the incongruent audio and visual combinations. But if they lack an understanding of hierarchical structure in noun phrases, then they will remain disinterested in the incongruent stimuli.