The development of Japanese as a second language

This chapter represents a new development in the studies on L2 Japanese in so far as, first, it updates the schedules for morphological and syntactic development outlined in earlier work according to the changes to PT proposed by Bettoni & Di Biase in chapter 1 of this volume, and, second, in doing so, it explores the boundaries of PT-based hypotheses on the acquisition of Japanese syntax. Work on the acquisition of Japanese nominal and verbal morphology in the PT framework began with Doi&Yoshioka (1987, 1990),Huter (1996), Kawaguchi (2000, 2002), and Di Biase & Kawaguchi (2002). Then, Japanese L2 studies contributed substantially to the extended scope of PT. For example, Kawaguchi’s (2005) longitudinal study was the first to test the two new hypotheses known as “Extended PT” (i.e., the Topic Hypothesis and the Lexical Mapping Hypothesis proposed in Pienemann, Di Biase & Kawaguchi 2005). Furthermore, Kawaguchi (2007) reports on the acquisition of structures involving nonbasic V forms such as passives, causatives and benefactives, as well as exceptional Vs such as unaccusatives, all of which lexically require nondefault mapping – I use here Pinker’s (1984) expressions ‘nonbasic’ for V forms and ‘exceptional’ for V types introduced in ch. 1, § 4.2.2, this volume. Further, Kawaguchi’s (2009a) cross-sectional study involving 24 intermediate-advanced university learners presents a detailed analysis of the acquisition of causative constructions in relation to the Lexical Mapping Hypothesis. So far, this hypothesis has been applied also to other languages such as English (Kawaguchi 2013; Keatinge & Keßler 2009;Wang 2009) and Italian (Bettoni & Fratter 2013; Nuzzo 2012), but Japanese remains the only one for which it has been shown how to treat causative constructions within the PT framework. Kawaguchi’s series of studies deal with Japanese as a foreign language in an instructional setting involving university students in Australia, but her results find support in other contexts, such as those on child L2 acquisition of Japanese in a naturalistic environment (Iwasaki 2008), adult language acquisition of L2 Japanese in an intensive course (Iwasaki 2013), and significantly bilingual L1 acquisition in Japanese-English (Itani-Adams 2007, 2008, 2009, 2011, 2013). The current state of PT as applied to L2 Japanese involves in particular the development of syntax and a reanalysis of the data fromKawaguchi (2010) with regard to the Prominence Hypothesis, and Kawaguchi (2005) with regards to the Lexical Mapping Hypothesis. About the latter hypothesis, Japanese as an L2 is the only language besides English (cf. § 3.2, ch. 2, this volume) that tests empirically the intermediate stage of default mapping plus additional arguments, formally introduced by Bettoni & Di Biase in chapter 1, § 4.2.2