Predicting the birth of a spoken word

Significance The emergence of productive language is a critical milestone in a child’s life. Laboratory studies have identified many individual factors that contribute to word learning, and larger scale studies show correlations between aspects of the home environment and language outcomes. To date, no study has compared across many factors involved in word learning. We introduce a new ultradense set of recordings that capture a single child’s daily experience during the emergence of language. We show that words used in distinctive spatial, temporal, and linguistic contexts are produced earlier, suggesting they are easier to learn. These findings support the importance of multimodal context in word learning for one child and provide new methods for quantifying the quality of children’s language input. Children learn words through an accumulation of interactions grounded in context. Although many factors in the learning environment have been shown to contribute to word learning in individual studies, no empirical synthesis connects across factors. We introduce a new ultradense corpus of audio and video recordings of a single child’s life that allows us to measure the child’s experience of each word in his vocabulary. This corpus provides the first direct comparison, to our knowledge, between different predictors of the child’s production of individual words. We develop a series of new measures of the distinctiveness of the spatial, temporal, and linguistic contexts in which a word appears, and show that these measures are stronger predictors of learning than frequency of use and that, unlike frequency, they play a consistent role across different syntactic categories. Our findings provide a concrete instantiation of classic ideas about the role of coherent activities in word learning and demonstrate the value of multimodal data in understanding children’s language acquisition.