Estes, K. G., & Hurley, K. (2013). Infant‐directed prosody helps infants map sounds to meanings. Infancy, 18(5), 797-824.

Infant directed speech is an exaggerated and repetitive speaking style that adults use when addressing infants. This form of speech encompasses a higher pitch, greater pitch variation and longer durations of speech segments. Infant directed speech supports early language acquisition by helping infants break up the speech they hear into components and helps maintain infant attention. In this paper, the researchers examined how infant directed speech influences an infants’ ability to connect sounds with meanings, specifically words with objects.

In this study, 17-month-old infants were presented with pictures of a novel object while listening to a name for the object. The amount of time the child looked at the novel object was recorded. Typically, infants look at novel objects for a long time at first, but once they become familiar with the stimulus, they spend less time looking (i.e., they become habituated). This method is called a habituation word-learning task. In the first experiment, the infants heard adult directed speech, and in the second, infant-directed speech. A third experiment also used infant directed speech but included different examples of the same word being spoken (different pitch contours and durations of the same word).

The authors found that infants were able to learn the object-label associations when the stimuli were produced using infant directed speech. Infants’ word learning was improved when the labels were produced using infant directed speech that contained variability (Experiment 3).  This suggests that infants form stronger associations between objects and their labels when the sound of the labels contains variability (altered pitch and duration for the same label) such as those produced in Experiment 3. This variability mimics the variability found in naturalistic speech and appears to be critical in an infant’s ability to learn new words. 

Blogger: Monica DaSilva is completing her Masters of Science in Developmental Psychology in the Language and Working Memory Lab. Her work will examine how infant word learning is enhanced by prosodic cues in words (i.e., word stress).