Grain size units of Chinese handwriting: development and disorder.

The current study investigated the grain size of writing units used by children in copying Chinese characters using handwriting measures. In Experiment 1, 31 Grade 1 and 31 Grade 5 children studying in mainstream schools in Hong Kong were invited to copy 36 pseudo-characters on an Android tablet. The pseudo-characters were constructed by combining, in their legal positions, radicals that contain two logographemes. The pseudo-characters contain only high frequency radicals in one condition and only low frequency radicals in the other condition. Linear mixed effect modeling was used to analyze the significance of radical frequency, radical free-standing frequency, and logographeme frequency in predicting the inter-stroke intervals after controlling for inter-stroke distance and gestalt boundaries of radicals and logographemes. The results showed that all three frequency measures significantly predicted Grade 5 children's inter-stroke intervals while only logographeme frequency and radical free-standing frequency significantly predicted Grade 1 children's inter-stroke intervals. This indicated that older children demonstrated the use of both small and large grain size units in writing Chinese characters while younger children showed tendency to use small grain size units with the support of some large grain size units that they know in writing Chinese characters. In Experiment 2, a Grade 3 child with writing difficulties was assessed using the same task. Results showed that he demonstrated the use of only small grain size units in writing. Theoretical and clinical implications were discussed.