Proceedings of the Annual Meeting of the Cognitive Science Society

The present study examined whether acquisition of Japanese particles ga (nominative case marker) and wa (topic marker) is an indicator of Japanese-speaking children’s development of Theory of Mind (ToM). The two particles are different in that ga is attached to new information and wa marks old information and in that the former is acquired earlier than the latter. Mastering appropriate use of these two particles requires the ability to understand what is known or unknown to the hearer, hence it can potentially be a predictor of ToM development. The result of an online experiment with Japanese-speaking children aged 3 to 7 showed that accuracy in using wa was a reliable predictor of a successful performance in the False-Belief task while accuracy in using ga was not. We argue that completion of acquiring wa would indicate ToM of the children has developed well enough to pass the False-Belief tasks.