Longitudinal studies of disfluencies in two-year-old children.

Spontaneous speech samples of 500 words were recorded three times at 4-month intervals from 33 normally speaking children. A fourth speech sample was recorded from the 13 youngest children in the group after an additional 4-month interval (one year after the beginning of the study). There were indications in the data that the peak number of speech disfluencies occurred at the later part of age 2 or at the beginning of age 3. Results also showed that there was a continuous reduction in disfluencies for the group as a whole. However, the 13 younger 2-year-olds and the 20 older 2-year-olds exhibited dissimilar developmental trends of disfluency. Large individual differences were observed during the period of the study. Many children showed large fluctuations in the number of disfluencies from one testing period to the next. A short episode of stuttering was observed in one subject. Overall, it appeared that the year between age 2 and 3 is an unstable period in speech development as far as disfluency is concerned.