This study investigates the acquisition of the unaccusative-unergative distinction in L2
Japanese by English learners. The aim is to establish whether learners of Japanese are sensitive to
the lexical-semantic characteristics of verbs in similar ways as learners of Romance languages who
were found to follow the Split Intransitivity Hierarchy (Sorace, 1993a, 1995a). Two groups of
learners participated in the study, one consisting of learners who had not had any previous
exposure to Japanese outside the classroom, and the other consisting of learners at the end of a
9-month period of continuous stay in Japan. A control group of native Japanese speakers also
took part in the experiment. Subjects were tested on their knowledge of the different behavior of
unaccusative and unergative verbs with respect to quantifier floating (Miyagawa, 1989); the
native group was also tested on Case drop (Kageyama, 1993). The results show that both the
native and the nonnative speakers are conditioned by the Split Intransitivity Hierarchy in their
judgments on unergative verbs; however, their judgments on unaccusative verbs do not pattern
according to the predictions. It is argued that this difference stems from the ambiguity of the
Japanese input on unaccusative verbs, which are characterized by syntactic optionality.