THE ROLES OF LEXICAL SIZE, DEPTH, AND AUTOMATICITY OF WORD RECOGNITION ON READING COMPREHENSION

Abstract

This study is a cross-sectional investigation into the relationship among Japanese EFL learners’ vocabulary size, two aspects of depth of vocabulary knowledge, polysemy and collocational knowledge, and automaticity of word recognition specified as orthographic decoding speed and lexical meaning access speed, and the roles these aspects of lexical knowledge play in general academic reading comprehension as well as in each of five Reading Comprehension item types—Main Idea, Stated Details, Paraphrased Details, Guessing Vocabulary from Context, and Making Inferences. The participants (N = 166) were first- and second-year, non-English majors at a four-year, co-educational university in western Japan. The participants were gathered from seven intact classes, where they focused on developing reading skills for TOEIC. Data were obtained from six major instruments: the Reading Comprehension Test, the Vocabulary Size Measure, the Revised Word Associates Polysemy Test, the Revised Word Associates Collocation Test, the Lexical Decision Task, and the Antonym Semantic Decision Task. The first four tests were administered with pencil and paper over two months, and the latter two tests were administered during the summer vacation with individual participants using computer software that produced reaction time data. Before conducting the quantitative analyses, the paper and pencil based tests were analyzed using the Rasch dichotomous model to examine the validity and reliability of the instruments and to transform the raw scores into equal interval Rasch measures. Pearson correlation coefficients were calculated to investigate how these aspects of lexical knowledge were related, and hierarchical multiple regression analysis was conducted to determine to what extent these aspects of lexical knowledge contributed to the prediction of general reading comprehension as well as each of the five reading comprehension item types. In addition, using the percentage of correct answers, 12 anchor words across three lexical knowledge tests, the Vocabulary Size Measure, the Revised Word Associates Polysemy Test, and the Revised Word Associates Collocation, were analyzed to examine the possible presence of a hierarchical acquisitional pattern for the three aspects of lexical knowledge. The results showed strong correlations among the Vocabulary Size Measure, the Revised Word Associates Polysemy Test, and the Revised Word Associates Collocation Test, which suggested that vocabulary size and depth of vocabulary knowledge are closely related. This indicated that the more learners expand their written receptive vocabulary, the more likely they are to learn about various aspects of those words, such as their common collocation. On the contrary, none of the three lexical knowledge tests correlated significantly with the Lexical Decision Task and the Antonym Semantic Decision Task, which suggested that increases in vocabulary size and depth of lexical knowledge were not accompanied by the development of faster recognition of orthographic form or faster access to word meaning. Hence, this result implied that developing greater speed of lexical access lags behind increases in overall vocabulary size. Furthermore, the micro-analysis of 12 anchor words indicated that item dependency and considerable individual variation for each anchor word was present for the three aspects of lexical knowledge. The results also indicated that both vocabulary size and depth of lexical knowledge play significant roles in academic reading comprehension. Moreover, the two aspects of depth of vocabulary, polysemy and collocational knowledge, made unique contributions to the prediction of academic reading comprehension, which suggested that as learners’ vocabulary size approaches 3,000 words families, depth of lexical knowledge becomes increasingly important for academic reading comprehension. In a similar vein, the strong correlations among Guessing Vocabulary from Context item type, vocabulary size, and the two aspects of depth of vocabulary knowledge suggested that successful lexical guessing requires both a reasonably large vocabulary size and depth of lexical knowledge. That is, learners need to know the primary meaning of words, secondary meanings, and how the words relate to other words if they are to successfully guess the meaning of unknown words. The results also indicated that word recognition, specified as orthographic processing speed and lexical meaning access, did not uniquely contribute to the prediction of academic reading comprehension nor to the prediction of most of the five Reading Comprehension item types for the relatively low English proficiency participants in this study. Only orthographic processing speed predicted 5% of the variance in the Reading Comprehension Paraphrased Details item type; however, a plausible explanation for this finding is that it was caused by the difficulty of this item type. This finding is reasonable, as verbal efficiency theory (Perfetti, 1985) states that as lower-level processes are automatized, cognitive capacity is freed up. A possible explanation for the other insignificant results between the two reaction times tests and the other four Reading Comprehension item types is that the participants were under no pressure to complete the reading comprehension measure quickly, as it was an unspeeded test. Another plausible reason is that the participants’ L2 lexical proficiency was relatively low; therefore, they have not yet developed word recognition fluency. Finally, the results showed that the Reading Comprehension Main Idea item type and Paraphrased Details item type are more closely related to depth of vocabulary knowledge than to vocabulary size.