Effects of Depth and Breadth of Vocabulary Knowledge On English Reading Comprehension Among Korean High School Students

Abstract

Roles of vocabulary knowledge in reading comprehension have recently received increasing attention in the field of L2 vocabulary and reading research. Despite the consensus among researchers and practitioners that vocabulary knowledge is composed of at least two dimensions, breadth (size) and depth (quality), most research has been concerned predominantly with vocabulary breadth in comparison with vocabulary depth. The present study attempts to fill this gap by investigating roles of both breadth and depth of word knowledge in reading comprehension. With regard to the vocabulary depth, this study focuses on the semantic properties (i.e., synonymy, polysemy, and collocations). The participants were 98 Korean high school students in the 11th grade. To measure their breadth and depth of vocabulary knowledge, and reading comprehension, three main tests were administered: a Vocabulary Levels Test (VLT), a Word Associates Test (WAT), and a Reading Comprehension Test (RC). A supplementary test designed by the researcher, Vocabulary Knowledge in a Yes/No Format (VKS), was adopted in scoring WAT with the aim of reducing possible guessing effects on WAT, which was represented as WAT+VKS. The scores were analyzed through correlation and multiple regression analyses. The results revealed that a significant association existed between breadth and depth of vocabulary knowledge, and reading comprehension. The alternation from WAT to WAT+VKS for a depth measure rendered a stronger correlation between vocabulary depth and reading comprehension. Specifically, the strength of correlation between the depth dimension and reading comprehension exceeded that of the breadth and reading comprehension. It was also found that vocabulary depth and breadth each contributed significantly to the prediction of reading comprehension. The degree of predictability, however, increased when the combinations of the two dimensions were used as a predictor variable. Furthermore, the replacement of WAT with WAT+VKS led to the improvement in the predictive power of the vocabulary depth measure. The present study is expected to offer a finer understanding of L2 vocabulary knowledge and its crucial role in reading comprehension among L2 learners. It is proposed that theoretical considerations and pedagogical practices need to encompass not only simple expansion of vocabulary size but also enrichment of knowledge about words. Consequently, this well-balanced vocabulary knowledge would ensure a successful reading comprehension.