The purpose of this paper is to examine the acquisition of the topic marker –(n)un and the subject (nominative) marker –i/-ka in Korean. We will be concerned, in particular, with the way in which these case markers are produced over time, considering children's spontaneous speech as well as experimental data at several developmental time points. In this inquiry, we will be interested to find out how Korean children use or drop these markers on noun phrases, as well as how they produce or omit the entire topic/subject phrases over time, based on the pragmatic and syntactic properties governing them. We show the following developmental sequence of the stages: null topic/subject → bare nominal topic/subject → marked topic/subject. Once these markers emerge, the developmental sequences for the functions of the topic and subject markers are: contrastive topic → global/thematic topic and focus subject → neutral subject. The latter two sequences are surprising in terms of markedness because they proceed from ‘marked’ to ‘unmarked’, unlike the sequence null → bare → marked for the use and marking of topic and subject noun phrases.
Word order and case markers
As is well-known in the literature, Korean word order is, in general, regarded as fairly flexible; the preferred word order is either the SOV pattern, or a combination of SOV and OSV structures. Word order can vary for a variety of reasons, including topicality, focus, and emphasis, among others.