On The Predictive Validity Of Corpus-based Frequency Measures In L2 English Lexical Processing

This dissertation reports on a study that investigates the predictive validity of L1 English frequency measures in Chinese EFL learners' performance in an English visual lexical decision task.Fifty-nine university English-major students participated in the study.Students were further grouped according to their English proficiency.They first conducted the lexical decision task,then they were required to complete the Oxford quick placement test and a language background questionnaire.In the LDT,participants were asked to decide as quickly and accurately as possible whether the string of letters presented at the center of the computer screen was an English word or not.In the present study,the word frequency of occurrence for 183 words in the LDT was obtained from five English corpora,including KF(Kucera & Francis norms),CELEX,BNC(British National Corpus),SUBTLEX-UK and SUBTLEX-US.Correlation analyses were performed between the reaction time of these words and their log word frequency obtained from these five corpora respectively.The results showed that frequency measures based on English TV and movie subtitles(SUBTLEX-US and SUBTLEX-UK)outperformed the other three traditional written frequency measures in predicting RT data of words across the whole frequency spectrum for Chinese EFL learners.Word frequency affected word recognition more for EFL learners with lower English proficiency than those with higher English proficiency.The results also indicated that,compared with word-form frequency measures,lemma frequency measures showed no significant superiority in predicting RT data for Chinese EFL learners.The conclusion of the study was that word frequency counts provided by subtitle frequency measures performed best in predicting Chinese EFL learners' lexical decision time of English words.The results of the present study,especially the detailed comparisons among the five corpora,provide methodological implications for future EFL lexical research and pedagogical implications for EFL teaching.