The Japan Association of College English Teachers (JACET) NII-Electronic Library Service The JapanAssociation of College English Teachers {JACET) llICETJbwrnal 58 ceO14) 1-20 Using Latent Semantic Analysis to Promote the Effectiveness of Contextualized Vocabulary Learning HAMADA, Akira Graduate School,University of TsukuballThe Japan Society forthe Promotion of Science Abstract Although paired-associate learning, thetraditional method of learning new words, has been replaced by contextualized'vocabulary learning, evidence from empirical studies runs counter to theoretical accounts of the superiority of context. Recently, more attention has been directed toward the quality of contextual information thatleads to providing a word with various lexical properties such as orthographM morphology, syntax, meaning, and usage. This research applied a latent semantic analysis (LSA) to predict the outcomes of vocabulary learning by evaluating thesemantic similarities between a word and its context, that is, how typically a target word is placed in a context 'Ihree groups of different vocabulary learning strategy users Uapanese university students) deliberately learned 20 target words using contexts and completed a Vbcabulary Knowledge Scale test 'Ilhe results provided evidence that thecontexts of higher LSA values promoted the gains in knowledge of word rneanings and usage. In addition, tlie contexts of lower LSA values consistently reduced the learning outcomes, and such hindrance effecbs appeared in the less frequent strategy users of context, particularlyL These findings suggest that the semantic similarities computed by.LSA should be considered a critical factor to investigate the effectiveness of contextualized vocabulary learning. Kaywords: latent semantic analysis (LSA) , vocabulary learning, semantic similarity Introduction Vbcabulary knowledge isone of the essential factors of success in second and foreign language acquisition. Since traditional paired-associate learning, such as repeated memorizing of the word form and meaning, was replaced bycommunicative language teaching approaches (Krashen, 1989) , the role of context on vocabulary acquisition hasbeen exarnined not only in incidental (e.g., Bolgeg Balass, Landen, & Perfetti, 2008; Hamada, 2011; Webb, 2008) but also inintentional learning (e.g., Griffin, 1992; Hasegawa, 2013; Webb, 2007). In language communication, words seldom appear in isolation; instead, each word meaning is woven into a context to construct a coherent message. Usually, foreign language texthooks show students a particular topic or situation (e.g., sending email, booking a hotel, and shopping) and present lists of new words that appear in the context. For example, let us consider the fo11owing sentence, in which the target word is italicized (adopted from Webb, 2007, p. 80) . 1