ABSTRACT
This study analyzed the distribution of the sentence length and mean of dependency distances (MDD) in Japanese sentences, comparing data from random sources with that obtained from children's compositions, and identifying changes in distribution according to grade level. Findings reveal that the sentence length in random data is well suited to a geometric distribution, whereas MDD is well suited to a lognormal distribution. In contrast, data from children's compositions show a shift in the distribution of the number of clauses from a lognormal to a gamma distribution, depending on the school year, with MDD suiting a gamma distribution. Mean MDD increases exponentially with the logarithm of the number of clauses in random data, while it increases linearly in composition data, thus generally supporting previous findings that dependency distances are optimized in natural language. However, MDDs exhibit non-monotonic changes with grades, suggesting the complexity of children's language development.
Subject(s)
Depressive Disorder, Major , Language , Humans , Child , Language DevelopmentABSTRACT
To evaluate the development of children's writing ability, it is necessary not only to examine quantitative indices such as the dependency distance, but also to inquiry the types of structures they use. We conducted clause boundary labeling using Support Vector Machine (SVM) on a corpus of Japanese students' compositions to investigate the change in the tendency of clause use with the progression of school age. The analysis of clause label frequency per sentence exhibited an increase in attributive clauses, nominal clauses, quotation clauses, and continuous clauses, and a decrease in parallel clauses, conditional clauses, reason clauses, time clauses, indirect interrogative clauses, and main clauses. The analysis of dependency distance demonstrated that most of the clauses that increased had short dependency distances, while most of the clauses that decreased had long dependency distances, and that the frequency of clauses with small dependency distances increased relatively with increasing school age. In addition, there was a shift in clause selection among functionally similar clauses, such as from "-te" to continuous forms, from "-tara" to "-ba", and from "-kedo" and "-keredo" to "-ga". These results suggest a change in the children's lexical and grammatical choices, from coordinate to subordinate structures, and from spoken to written vocabulary.
