Studies of Japanese as a second language and their contribution to Processability Theory

In the field of second language acquisition (SLA), Japanese has an important role to play. The typological characteristics of Japanese stand in clear contrast to Germanic and other European language families. These characteristics have contributed significantly to SLA, establishing crosslinguistic plausibility of developmental sequences in SLA theories, including Processability Theory (PT). This chapter surveys major studies in Japanese SLA over the last two decades, particularly those conducted within the PT framework, to account for the steps forward in understanding morphological and syntactic development of Japanese as a second language in adults, children, and bilingual first language acquisition. Furthermore, the aspects which lag and require further research effort are also discussed.