Abstract
Literacy exposure checklists that assess parental picture book knowledge (Parental Title Checklist [PTC] and Parental Author Checklist [PAC]) have been developed as proxy measures for literacy environments. Although previous research suggests that parental picture book knowledge is a strong predictor of language skills for preschoolers older than 3 years of age, it remains unclear whether it is related to vocabulary acquisition in children younger than 2 years of age. Using checklists of parental picture book knowledge (PTC and PAC) and self-report questionnaires of literacy environments (reading frequency, number of children’s books at home, frequency of library visits, age at which reading started), this present research investigated whether such literacy environments are related to vocabulary acquisition in 15-month-olds Japanese. Our results showed that PTC makes a unique contribution to the prediction of children’s comprehensive vocabulary scores, and both PTC and PAC predict their productive vocabulary after controlling for maternal education levels. We discuss the influence of parental picture book knowledge on children’s language development and conclude that the effects of such knowledge are even applicable at 15 months.