The Association Between Socioeconomic Status and Oral Vocabulary in Young Children: A Quantitative Meta-Analysis

Hart and Risley claimed the existence of an association between socioeconomic status (SES) and oral language competence, having found that children from lower SES backgrounds presented with less-developed vocabulary than children from higher SES backgrounds. The purpose of this study was to examine the accuracy and generalisability of Hart and Risley’s original finding by quantifying the association between SES and oral vocabulary test scores through systematic review and meta-analysis. Papers including data collected between 2012 and 2022 and examining the association between SES and oral vocabulary test scores through either a correlational or group comparison design were considered for inclusion. Following a database search for peer-reviewed articles, 3055 articles were subjected to title and abstract screening, and 209 were retrieved for full-text screening. In total, 17 relevant studies were identified through systematic review, with nine countries and seven languages represented. The meta-analysis of correlation coefficients for the association between SES and oral vocabulary included 10 studies, drawing upon the data of 9742 children, and yielded a combined positive effect size of approximately moderate magnitude ( r = .27). The meta-analysis of standardised mean differences in oral vocabulary between lower and higher SES groups included seven studies, drawing upon the data of 1491 children and yielded a statistically significant combined effect size of strong magnitude ( g = −0.93) in favour of higher SES groups. These findings confirm the existence of a substantial positive association between SES and oral vocabulary test scores evident in modern societies internationally. The importance of interpreting these results precisely is emphasised.