Decontextualized Utterances Contain More Typical and Stuttering-Like Disfluencies in Preschoolers Who Do and Do Not Stutter.

Abstract

Stuttering-like disfluencies (SLDs) and typical disfluencies (TDs) are both more likely to occur as utterance length increases. However, longer and shorter utterances differ by more than the number of morphemes: They may also serve different communicative functions or describe different ideas. Decontextualized language, or language that describes events and concepts outside of the "here and now," is associated with longer utterances. Prior work has shown that language samples taken in decontextualized contexts contain more disfluencies, but averaging across an entire language sample creates a confound between utterance length and decontextualization as contributors to stuttering. We coded individual utterances from naturalistic play samples to test the hypothesis that decontextualized language leads to increased disfluencies above and beyond the effects of utterance length. We used archival transcripts of language samples from 15 preschool children who stutter (CWS) and 15 age- and sex-matched children who do not stutter (CWNS). Utterances were coded as either contextualized or decontextualized, and we used mixed-effects logistic regression to investigate the impact of utterance length and decontextualization on SLDs and TDs. CWS were more likely to stutter when producing decontextualized utterances, even when controlling for utterance length. An interaction between decontextualization and utterance length indicated that the effect of decontextualization was greatest for shorter utterances. TDs increased in decontextualized utterances when controlling for utterance length for both CWS and CWNS. The effect of decontextualization on TDs did not differ statistically between the two groups. The increased working memory demands associated with decontextualized language contribute to increased language planning effort. This leads to increased TD in CWS and CWNS. Under a multifactorial dynamic model of stuttering, the increased language demands may also contribute to increased stuttering in CWS due to instabilities in their speech motor systems.