Effect of linguistic factors on the occurrence of stuttering-like disfluency among Japanese-speaking preschool children who stutter.

This study aimed to investigate the linguistic factors involved in stuttering among Japanese-speaking preschool children. The participants included 10 Japanese children who stutter, with a mean age of 5 years and 9 months. Speech samples comprised spontaneous conversations of the participants with their parents for about 20 minutes. We compared the percentages of the occurrence of stuttering-like disfluencies (SLDs) at the word and sentence levels, using the Wilcoxon signed-rank test. The results showed no significant differences in SLDs based on syllable structure when comparing light and heavy syllables and comparing consonants and vowels in the initial position of each content word. SLDs occurred more frequently in the initial than non-initial position of words and in longer rather than shorter words. Additionally, SLDs occurred more frequently in sentences that contained more 'bunsetsu' (a kind of linguistic unit in Japanese). Our study is the first to show that both word and sentence-level factors could contribute to SLDs in preschool children who stutter in agglutinating languages, such as Japanese. This aspect is rarely reported in psycholinguistic studies based on stuttering occurrence in inflecting languages, such as English.