| This dissertation investigates processing of English and Japanese relative clause (RC) sentences by native speakers and second/foreign language (L2) learners. Particularly, the relationship between the sentence processing and individual differences in working memory (WM) capacity was examined. The main question addressed in this study is whether the performances of L2 learners in processing RCs are similar to those of native speakers depending on one's WM capacity.;Two major approaches regarding the processing of RCs have been proposed to account for the differences between the difficulty of the subject-gap and the object-gap sentences: the cost of resources taken up by temporary storage and integration when processing (Dependency Locality Theory; Gibson, 1998, 2000) and the depth of embedding of the extracted element (Structural Distance Hypothesis; O'Grady, 1987; O'Grady, Yamashita, Lee, Choo and Cho, 2000). This study also evaluated these two hypotheses and answers the question: To which hypothesis do the performances of L2 learners best correspond?;Fourteen English native speakers who were Japanese language learners and 14 Japanese native speakers who were English language learners participated in the experiment, which consisted of three parts: First language (L1) and L2 reading span tests, L1 and L2 self-paced moving window reading tasks, and a L2 proficiency test. The comprehension accuracy rates of the experimental sentences and individuals' residual reading times in each region of the RC sentence types were used for comparisons. Additionally, the individual participants' sentence reading patterns were examined, so what may have been invisible on the group level analyses were revealed.;The results of the experiments showed that (1) English object-gap sentences are more difficult to comprehend than English subject-gap sentences for both L1 native speakers and L2 learners, (2) Japanese subject-gap sentences are more difficult to comprehend than Japanese object-gap sentences for both L1 native speakers and L2 learners, which supported Dependency Locality Theory and (3) the differences in comprehension accuracy rates, if any, were seen between the lower WM L2 learners and the group of the higher WM L2 learners and the native speakers. The results of the individual reading pattern comparisons showed that (4) there seems to be a commonly-preferred reading pattern among the native speakers in processing the subject-gap and object-gap sentences, and (5) L2 learners who demonstrated reading patterns dissimilar to the L1 native speakers' commonly-preferred reading pattern showed a tendency of having a lower WM capacity, and both of these tended to have an effect on L2 comprehension accuracy.;It was concluded that the performances of L2 learners in processing RCs can be similar or dissimilar to those of native speakers depending on one's WM capacity. It was also concluded that having a lower WM capacity seems to hinder processing a sentence in a way similar to the native speakers. Moreover, for L2 learners, being unable to process L2 sentences in the manner that is commonly preferred by the native speakers seems to lead to lower comprehension accuracy in the RC sentences, especially in the more-difficult-to-comprehend English object-gap and Japanese subject-gap sentences. |
