The influence of infant characteristics and attention to social cues on early vocabulary.

Individual differences in early language development are related to a number of infant characteristics and skills, including temperament traits, cognitive ability, and social cognition. The current study aimed to assess the complex mechanisms underlying these relations by evaluating the ability to use social cues in a word-learning context along with temperament, cognitive ability, and expressive vocabulary in 71 18-month-old infants. A moderated mediation analysis indicated that infants' nonverbal cognitive ability affects their early vocabulary through its effect on their ability to use social cues, but only in infants with low nonverbal cognitive ability. Implications for both typical and atypical development are discussed.