To investigate the relationship between normal childhood disfluency and stuttering, various types of normal childhood disfluency were examined in relation to age and levels of sentence structure acquisition. The subjects were 50 nursery school children, aged 2 to 6, whose conversational utterances in play situation have been tape recorded and analyzed. The major findings were as follows:
1) Frequency of each type of disfluency tended to increase in children from 2 to 4 years old and to decrease in 5 and 6 years old children.
2) The percentages of children who used longer sentences and various types of sentences tended to increase in children from 2 to 4 years old.
3) The children using the greater number of different types of sentences showed the higher frequency of disf luency.
4) Increase and decrease of each type of disfluency showed similar tendency in relation to age and levels of sentence structure.
Taken together, these results were interpreted to indicate that normal childhood disfluency tends to increase at a certain stage of language acquisition and then decrease afterwards.