Lexical influence on phonological processing in adults with and without stuttering

Purpose: The purpose of this study was to investigate how phonetic complexity influences the accuracy and rate of speech production in adults who do (AWS, N=15) and do not stutter (AWNS, N=15). Target words were characterized according to high phonetic complexity (HIPC) and low phonetic complexity (LIPC), and were controlled for lexical influences such as word frequency and neighborhood density. It was hypothesized that if phonetic complexity influenced speech production, there would be a difference in reaction time and accuracy for AWS during the HIPC condition. Method: Participants produced two rounds of 40 target words corresponding to specific line drawings, during a confrontational naming task. Speech reaction time (SRT) was recorded from initial presentation of picture, and fluency and accuracy of production were coded for each target. Results: There was no significant difference in SRT according to HIPC and LIPC for either AWS or AWNS. AWS participants had slower SRT recorded compared to AWNS for all conditions tested. There was no relationship found between HIPC and increased moments of disfluency. Accuracy of target word production decreased during LIPC words. Conclusion: Phonetic complexity does not affect rate or fluency of speech production for either AWS or AWNS. While there is no difference in phonetic complexity measures, AWS are consistently slower than AWNS across both groups of target productions. Increased errors for both groups on LIPC target words may indicate a motor component to accuracy of speech production.