Disfluencies and phonological revisions in a nonword repetition task in school-age children who stutter.

Phonological encoding and associated functions, including monitoring of covert and overt speech, have been attributed relevant roles in stuttering. The aim of this study was to investigate these processes by testing the effects of nonword length in syllables (3-, 4-, 6-syllable), phonotactics, and phonemic/phonetic complexity on disfluencies and phonological revisions in 26 school-age children who stutter (CWS, n = 13) and matched fluent controls (CWNS). Participants repeated nonwords in two sessions separated by an hour. Within-group comparisons of percentage disfluencies using nonparametric tests resulted in significantly more disfluencies for the 6- compared to the 3-syllable nonwords and suggested that nonword length influences disfluencies in the CWS. The groups were comparable in the percentage of disfluencies at all levels of nonword length. The findings failed to provide conclusive evidence that phonological complexity and phonotactic manipulations have a greater effect on disfluencies in CWS compared to CWNS. The findings of significantly fewer phonological revisions and the lack of a significant correlation between disfluencies and revisions in the CWS in Session 1 compared to the CWNS are interpreted to suggest reduced external auditory monitoring. Demands on incremental phonological encoding with increasing task complexity (the Covert Repair Hypothesis, Postma & Kolk, 1993) and reduced external auditory monitoring of stuttered speech can account for the disfluencies, speech errors, and revisions in the speech of school-age CWS.

Movement kinematics and speech accuracy in a nonword repetition task in school-age children who stutter.

We investigated sensorimotor processes in school-age children who do (CWS) and do not stutter (CWNS) in a nonword repetition (NWR) task and evaluated changes in behavioral (percent speech accuracy) and speech kinematics measures (lip aperture variability, movement duration) with practice and retention. Thirteen CWS and 13 CWNS divided into two age groups (younger, 8-12 years; n = 6, older, 13-15 years, n = 7) repeated nonwords varying in phonological properties over two sessions separated by an hour. Participants in both groups also completed several baseline measures, including tests of digit span and nonword repetition (NRT). A marginal trend for lower speech accuracy was noted in the CWS compared to the CWNS in the NWR task. The younger CWS also performed poorly compared to the older CWS and age-matched CWNS in the NRT. Findings provided weak support for limitations in initial encoding and subsequent retrieval of phonemic information. The CWS demonstrated significantly reduced inter-articulatory coordination for the 3-syllable nonwords. While both groups demonstrated significantly slower movements with increase in nonword complexity at the 3-syllable level, such differences were enhanced in the CWS group and influenced further by participant age. Additionally, digit span influenced movement coordination in both groups with only the CWNS showing a significant negative correlation between the digit span scores and movement variability at the onset of practice in Session 1. The findings offer limited support for a sensorimotor integration deficit in CWS and the contributions of cognitive mechanisms to performance in NWR.