Effects of syntactic complexity and sentence-structure priming on speech initiation time in adults who stutter

To test the hypotheses that adults who stutter will be slower in producing syntactically complex sentences than fluent adults and will benefit more from sentence-structure priming than will fluent adults.

Adults who stutter (n = 15) and fluent adults (n = 15) participated in 2 experiments. In Experiment 1, adults in both groups were administered a task that required memorization and production of sentences that varied in syntactic complexity. The same individuals who participated in Experiment 1 also participated in Experiment 2. The second experiment required all participants to create and produce sentences under primed and unprimed sentence-structure conditions.

Relative to adults who do not stutter, the speech initiation time of fluent utterances of adults who stutter became increasingly slower as syntactic complexity increased, and they exhibited greater facilitative effects of sentence-structure priming. In addition, adults who stutter showed a significant correlation between syntactic complexity and priming facilitation.

Data from these experiments confirmed both hypotheses and provided evidence that a subgroup of adults who stutter have grammatical encoding differences when compared with adults who do not stutter.