Koyanagi, Kaoru. (1998). The effect of instruction on the acquisition of conditionals. Acquisition of Japanese as a Second Language. 2, 1-26. [Article written in Japanese]

小柳かおる(1998). 「条件文習得におけるインストラクションの効果」『第二言語としての日本語の習得研究』2, 1-26.

This study tried to show the effects of instruction or whether instruction makes a difference for learners of Japanese whose L1 is American English to acquire Japanese conditional forms, to, ba, tara, and nara. Japanese conditional forms are regarded to be difficult for English speakers to acquire because time the sequence restriction and modality restriction in conditional clauses are different in two languages (Japanese and English). The time sequence restriction is a kind of restriction that when one uses conditional clauses using to, ba, or tara, the antecedent should happen before apodosis (post-condition) in Japanese grammar, whereas this restriction does not apply for the conditional clause with “if” or “when” in English language as it is more flexible in terms of sequence. Citing “Subset Principle” Berwick’s “Subset Principle” (1985), she suggested that if the learner’s own L1 grammar covers a wider area than that of the target language’s grammar, the learner should learn the negative evidence by explicit instruction highlighting the point to better understand the area of sequence. Also, the Japanese modality restriction is different from English. In an English sentence with conditional clause, one can put both [-modality] sentence (i.e., fact statement, judgement, etc.) and [+modality] sentence (i.e., order, request, prohibition, suggestion, invitation, hope, and so forth); whereas in a Japanese sentence, [+modality] cannot be used with conditional markers to and ba, and this causes the delay or failure of learners’ acquisition of this type. It is also necessary to teach learners of English explicitly to close the gap between the ways the feature is used in both languages.