| This thesis research explored the relationships among vocabulary size, depth of vocabulary knowledge, and reading comprehension in English as a second language (ESL). Specifically, using multivariate and content analyses, the research assessed the role of depth of vocabulary knowledge in 74 adult Chinese and Korean speakers' comprehension of general academic texts in English. The main study examined to what extent depth of vocabulary knowledge adds to the prediction of reading comprehension scores over and above the prediction afforded by vocabulary size, employing as instruments a portfolio of vocabulary knowledge tests, a reading comprehension test, and a background questionnaire. A follow-up study then investigated strategies for processing the meaning of unknown words used by a subsample of these ESL learners with different depths of vocabulary knowledge. For this purpose, individual interviews and a survey questionnaire on reading strategies were used as the main means of data collection.;Among other findings, the research produced empirical evidence that: (a) scores on vocabulary size, depth of vocabulary knowledge, and reading comprehension were positively, and closely, related; (b) depth of vocabulary knowledge made a unique contribution to the prediction of reading comprehension scores, over and above the prediction afforded by vocabulary size; (c) depth of vocabulary knowledge played a fundamental role in these ESL learners' reading comprehension processes; (d) there was a positive relationship between the learners' depth of vocabulary knowledge and their lexical inferencing ability; and (e) in processing the meaning of unknown words, all learners looked for cues to meaning, but those with greater depth of vocabulary knowledge appeared to focus more on word meanings, whereas learners with less depth of vocabulary knowledge tended to focus more on word forms. The results of this research point to the importance and necessity of improving the depth of learners' vocabulary knowledge in their ESL learning. |
