Researchers have been interested in the question of when different mood and modal elements are acquired in early childhood in different languages. This interest has stimulated discussion of theoretical issues regarding pragmatic, semantic and syntactic processes in different developmental stages of child language. This chapter is mainly concerned with how early mood/modal elements, along with temporal/aspectual and other functional elements, are acquired in Korean. Other related investigations include S. Choi's (1995) study of epistemic modals in cognitive development and H. Han's research (in this volume) on functional categories in generative grammar.
All inflectional elements, including modals, are acquired rather late – after 2 years of age – in Indo-European languages including English (Radford, 1990). However, in the acquisition of Korean, a verb-final language, sentential endings encoding a variety of moods, sentence types, modal differences, and even politeness are acquired much earlier. This study will investigate in what order these mood/modality indicators are acquired and what aspects of cognitive and linguistic development the data illuminate. Whether functional categories or projections, as elements of universal grammar, can be found in child grammar is also an interesting theoretical question to consider.
This study is based on my longitudinal diary notes on my own children (SK=Suh-Kyung, daughter, and CK=Choon-Kyu, son) from the babbling stage to over 10 years of age. These notes will be regularly compared with diary notes from a female child relative (YJ=Yoon-Jung) and an additional male child (H=Hyuki, a colleague's son) for tense/aspect.