Working Memory Capacity, Vocabulary Knowledge, and Reading Comprehension of EFL Learners

This study examined the combined and relative predictive powers of working memory capacity (WMC) and vocabulary knowledge in literal and inferential reading comprehension of English as a foreign language (EFL) learners. To that end, forty-six university students in Korea performed a battery of tests: (a) the reading span task as a measure of WMC; (b) the Nelson-Denny Comprehension Test; and (c) the Vocabulary Test. Results showed that WMC and vocabulary knowledge accounted for 21.7% of the variance in literal reading comprehension scores with a medium effect size. With regard to inferential reading comprehension, vocabulary knowledge alone explained 33.1% of the variance with a large effect size. Concerning relative predictive values, WMC was more useful than vocabulary knowledge in explaining literal reading comprehension performance, whereas in inferential reading comprehension, text-specific vocabulary knowledge was the only significant predictor.