Factors Associated with Individual Differences in Vocabulary Acquisition

Author: Young-Suk Kim
Presented at 2017 AERA

​Abstract: Vocabulary knowledge is essential for oral language communication, literacy acquisition, and discourse-level language comprehension and production (Florit, Roch, & Loverato, 2011; Lepola et al., 2012). Vocabulary is also a strong predictor of reading comprehension (e.g., see National Institute of Child Health and Human Development [NICHD], 2000 and Elleman, Lindo, Morphy, & Compton, 2009) and writing (Olinghouse & Leaird, 2009). Given its importance, it is vital to have a clear understanding of factors involved in vocabulary acquisition. One well-known, critical factor for vocabulary acquisition is exposure frequency. Large standard deviations in previous vocabulary intervention studies (e.g., Biemiller & Boote, 2006; Coyne et al., 2010; Townsend & Collins, 2009) show that children with the same vocabulary exposure can vary substantially in vocabulary acquisition. A naturally rising question is what factors explain individual differences in vocabulary acquisition? In the present study, this question was addressed by examining several predictors supported by previous research, including attentional control, working memory (phonological memory in particular), inference, and grammatical knowledge. We examined how the vocabulary of 262 kindergartners (Mean age = 5.33), as measured by the Woodcock Johnson-III Picture Vocabulary is predicted by four variables: (a) working memory—a listening span task (Kim, 2016; Kim & Schatschneider, in press), (b) attentional control—SWAN (Strengths and Weaknesses of ADHD symptoms and Normal behavior scale, Swanson et al., 2006), (c) grammatical knowledge—an adapted task from the Grammaticality Judgment task of CASL (Comprehensive Assessment of Spoken Language, Carrow-Woolfolk, 1999), and (d) inference—an adapted task from the CASL Inference task. Reliability estimates were greater than .70. The mean standard score of vocabulary for the sample was average (M = 99.40, SD = 9.29). A multiple regression analysis was conducted controlling for children’s age. As shown in Table 1-1, results showed that individual differences in attentional control, working memory, grammatical knowledge, and inference were all independently related to vocabulary.