The continuing significance of early vocabulary development

• In Event: Ensuring Quality Care for Infants/Toddlers: Early Language Development and Program Characteristics and Opportunities

Abstract

Where are the points of maximum leverage in facilitating early development with the goal of optimizing eventual achievement? Two key criteria are (1) prediction within the targeted domain, and (2) the existence of cross-domain effects. There is substantial evidence of both kinds for early language development, especially vocabulary as measured in the first three years of life during infancy and toddlerhood. However, there are limitations to this conclusion: few studies have examined outcomes beyond the first decade of life; population-representative samples have generally not been included; focus has generally been on the full distribution or performance at the low end but not both; and prediction of high performance has generally not been included despite its importance both to individuals and to societal development. In this longitudinal study, we asked: How well can educational achievement measured in the final year (Grade 9, age 15) of compulsory education, both overall and for outcomes in the lowest and highest 20%, be predicted from vocabulary skills in the first three years of life, particularly early expressive vocabulary? To what extent are cross-domain effects observed?
Measures for 2767 children (1345 males, 1422 females) aged 16-30 months on early expressive vocabulary, along with family SES (parental education, occupation, and household income), other demographic information (e.g., gender, birth order, parental age, social), timing and nature of early childcare, and early home literacy experience, were used to predict performance on Danish Upper Secondary School Leaving Exam (USSLE) in Danish, English, Math, and Science. A cross-validated combination of Lasso (Least absolute shrinkage and selection operator) and ordinary least squares regression was the primary analysis for continuous outcomes, and cross-validated Lasso and logistic regression for categorical outcomes. With respect to continuous, full-range outcome measures, the patterns of prediction varied with specific domain; R2 ranged from 9.4% to 21.4%. With respect to low USSLE performance, Area Under the Curve (AUC) statistics ranged from 64.1% to 72.2%. For high USSLE performance, AUC ranged from 64.0% to 77.1%. In all four USSLE domains and for the entire sample, early childhood expressive vocabulary made a significant and unique contribution to Grade 9 achievement outcome beyond family, demographic, and childcare variables. Prediction from early vocabulary was also significant to low Danish and English scores, as well as to high Danish and English scores, though not for Math and Science in either case. Positive Likelihood Ratios for low performance (20% cutoff for both measures) ranged from 2.06 to 2.62; Negative Likelihood Ratios ranged from .74 to .81. The results demonstrate that low early vocabulary is an important and measurable risk condition which can direct early intervention and thus contribute to later educational attainment. The very similar results for high USSLE performance may motivate more consideration of appropriate intervention to maintain and foster high performance.

Author

• Philip S Dale, University of New Mexico
  Presenting Author