Semantic Processing: The L2 Lexical Competence Perspective

The present study is intended to investigate two factors relating to the retrieval of semantic meanings of words in the second language mental lexicon. The first factor has to do with L2 vocabulary knowledge, which is believed to facilitate L2 semantic processing at a word level. The second factor is concerned with individual differences in working memory capacity, which is assumed to constrain L2 semantic processing. With adult Chinese-speaking learners of English as subjects, this study aims to reveal three kinds of relationships: (a) between L2 vocabulary knowledge and efficiency of L2 semantic processing, (b) between individual differences in working memory capacity and efficiency of L2 semantic processing, and (c) between L2 vocabulary knowledge and individual differences in working memory capacity. Hopefully, the results thus obtained will cast light on the processes of L2 lexical development and the development of the second language mental lexicon.To this end, three experiments have been run within a conceptual framework of L2 lexical competence, which was specially developed for the current research. Experiment 1 tested the L2 vocabulary knowledge hypothesis, which postulated that L2 vocabulary knowledge would affect efficiency of L2 semantic processing for Chinese learners of English. A primed lexical decision task was used to assess the learners' efficiency of L2 semantic processing and the Controlled Active Vocabulary Test was administrated to determine their L2 vocabulary knowledge. The results showed that the learners of high-level L2 vocabulary knowledge were significantly quicker and more accurate than those of low-level L2 vocabulary knowledge regarding accessibility of semantic knowledge in the L2 mental lexicon. Furthermore, semantic priming effects did not increase with the development of L2 vocabulary knowledge.Experiment 2 tested the links hypothesis, which stated that links in lexical networks of Chinese-speaking learners of English would influence the changes in efficiency of L2 semantic processing. For this purpose, a task of restricted word association was adopted. The results showed that the pattern of responses in the lexical networks of learners with richer vocabulary knowledge was significantly different from that in the lexical networks of learners with poorer vocabulary knowledge. The findings from Experiment 2 lent support to an explanation of a weaker semantic priming effect achieved by the learners with higher level of vocabulary knowledge, which attributes the weaker effect to better-structured lexical networks in the light of the compound cue theory.Experiment 3 examined the issue concerning whether access to word meanings in the L2 mental lexicon would be constrained by individual differences in working memory capacity of Chinese-speaking learners of English. It also looked into the correlations between L2 vocabulary knowledge and individual differences in working memory capacity in order to attain a better understanding of the nature of L2 vocabulary knowledge. Using the operation span task as the measure of the language-unrelated working memory capacity based on the general capacity model proposed by Engle et al. (1992), the results from this experiment revealed a null effect of working memory capacity. Nevertheless, a pattern of slower (not significant) response latency was observed for the learners of high span than that for the learners of low span in the group of high-level vocabulary knowledge, but this pattern was not evident in the group of low-level vocabulary knowledge. The results also showed that L2 vocabulary knowledge was not correlated with individual differences in working memory capacity.So, the present study finds that second language vocabulary knowledge facilitates acquisition of L2 lexical competence because it contributes not only to the build-up of a lexical network, but also access to word knowledge in the L2 mental lexicon. The study also finds that working memory capacity does not seem to constrain the retrieval of word meanings when...