Alternative Title日本人EFL学習者の語彙サイズ、語彙学習方略使用、動機づけ、および自己効力感における発達過程の縦断的分析
Note (General)This study investigates growth in vocabulary size and potential causal factors in a three-year high school EFL course in Japan. The study is presented in two phases: (1) the validation and equating of three vocabulary size tests using Rasch analysis, and (2) a longitudinal analysis of growth in vocabulary size and its relationship to four individual differences: use of vocabulary learning strategies, motivation, self-efficacy, and time on task. The participants were 189 Japanese high school EFL learners majoring in science and engineering, ranging in age from 16 to 18. Measurements of vocabulary size and the three individual differences were taken in April of their first, second, and third year and again in December of their third year, at a National Institute of Technology (NIT) in Japan.The first phase of the research involved a Rasch analysis and linking of vocabulary size measures. Although the three forms of the Vocabulary Size Test (VST) created by Aizawa and Mochizuki (2010) were designed to be of equal difficulty, formal equating of the three forms had not been carried out. In order to verify whether gains in test scores were due to growth in vocabulary size or differences in difficulty among the three forms, a fourth form (VST 4) comprised of items selected from VST 1–3 was developed and administered in December of Year 3. The four test forms were then equated using Rasch analysis, placing persons and items on a single, uniform logit scale. The study systematically describes a method for equating test forms that lack common items, as well as a Rasch-based method for estimating total vocabulary size based on test scores. The first phase provides additional insight into the relationship between word frequency and word difficulty, and concludes that participants, on average, increased their vocabulary size by about 1,000 lemma during their three-year course of study.The second phase of the research examined relationships among vocabulary size, use of vocabulary learning strategies, motivation, self-efficacy, and time on task. Longitudinal descriptive plots indicated that both strategy use and motivation decreased somewhat at the beginning of the second year (Time 2) and then fluctuated slightly during the remainder of the study. Cluster analysis of a vocabulary learning strategies questionnaire administered at the end of Year 3 (Time 4) identified three learner profiles, which were labeled High, Medium, and Low frequency strategy users. The High group were particularly frequent in their use of higher-order strategies such as metacognitive, grouping, and contextualizing strategies. Qualitative analysis of an open-ended questionnaire added additional insight into how the three groups used vocabulary learning strategies. A two-way repeated measures ANOVA demonstrated that the strategy use profiles were significantly related to vocabulary size at all four time points, as well as the rate of gain in vocabulary size over three years.A second cluster analysis based on longitudinal measures of vocabulary learning strategy use identified four clusters. Cluster 1 used strategies frequently and consistently throughout the three years. Cluster 2 used strategies consistently but somewhat less frequently than the first group. Cluster 3, however, showed a substantial decline in strategy use at Time 2 and then slowly recovered to match Cluster 2 at Time 4. Finally, Cluster 4 began as low frequency users of strategies and continued to decrease their use even further during the course of the study. A second two-way repeated measures ANOVA confirmed a significant relationship between longitudinal strategy use patterns and vocabulary size at each time point, as well as the rate of growth in vocabulary size.In a final analysis, structural equation modeling (SEM) was employed to investigate relationships among estimated vocabulary size and the individual difference measures at Time 4. Two models were specified and tested. A simple model demonstrated that vocabulary learning strategy use directly and positively influenced vocabulary size, while motivation had a positive influence on frequency of strategy use but did not directly influence vocabulary size. A second model added self-efficacy and time on task in a reciprocal path. Success at learning vocabulary positively influenced self-efficacy, which in turn increased motivation, which positively influenced both strategy use and time on task. Strategy use then directly influenced vocabulary size, creating a virtuous circle. The final model showed good fit to the data (CMIN/DF = 2.080, CFI = .931, PCFI = .692, RMSEA = .076).Training in the implementation of certain higher order vocabulary learning strategies, such as grouping by semantic theme or type of affix employed, was included as a regular part of classroom instruction by the researcher and other teachers at the research site during the course of the study. Although the study was not designed to directly investigate the efficacy of strategy training, a steady increase in the use of these strategies was noted in the results. Consequently, the study has included a detailed description of materials and methods employed for strategy training at the research site.
2022
Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2023-05-05T22:12:33+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション