抄録
The present study set out to explore the role of positive evidence (exemplars), metalinguistic information (explicit explanations), and the combined treatment (a combination of positive evidence and metalinguistic information) for L2 lexico-semantic development, or the acquisition of L2 word meanings. 47 Japanese university students studied semantic differences between two members of 12 pairs of English words (e.g., big-large, learn-study, and borrow-rent) in one of the following four conditions: the control, positive evidence, metalinguistic, and combined conditions. Major findings can be summarized as follows: (1) positive evidence, metalinguistic information, and the combined treatment may foster semantic development at least temporarily, (2) effects of metalinguistic information and the combined treatment may be retained over two weeks, whereas those of positive evidence may not, and (3) metalinguistic information and the combined treatment might be more effective than positive evidence both in the short and long term. The limited effectiveness of positive evidence might be partially ascribed to the unique condition under which a L2 is learned, namely, the presence of an established L1 lexical system and the lack of access to internal assumptions about the lexicon.