[PS-2.1] Acquisition of mental state language in Japanese-speaking children: Analysis using large-scale vocabulary-checklist data

OKUMURA, Y. 1 , KOBAYASHI, T. 1 & MINAMI, Y. 2

1 NTT Communication Science Laboratories
2 The University of Electro-Communications

Given the relationship between children's socio-cognitive understanding such as theory of mind (ToM) and their acquisition of mental state language (MSL) (Taumoepeau & Ruffman, 2006), it is among the most important issues to grasp when children begin to produce each word of MSL. However, due to some methodological problems, previous research could not determine the exact age of acquisition in MSL. The present study explored Japanese-speaking children's acquisition of MSL by collecting large-scale vocabulary-checklist data. Parents of children aged 8-48 months (N=1,285) were asked to check whether their child produced each word of MSL. From large-scale data, we estimated (1) the age at which 50% of children produced each word of MSL by logistic regression and (2) the acquisition order for each word type such as cognition, emotion, and desire words. At earlier stages, 50% of children produced emotion words such as "fearful" by 23.8 months, and desire words such as "like" by 26.3 months. They later used cognition words such as "understand" by 34.9 months. Thus, Japanese-speaking children acquired emotion and desire words earlier than cognition words. These findings are discussed in light of the delay of ToM performance in Japanese-speaking children and input frequency in picture books.