Many authors agree that disfluencies are a byproduct of speech encoding difficulties. However, it is unclear which phenomena specifically reflect word form retrieval difficulties, such as those commonly observed in typical aging and tip-of-the-tongue states. This retrospective descriptive study examined the relationship between word-form retrieval difficulties and speech disfluencies in typically aging older adults, using the framework of the Transmission Deficit Hypothesis. Twenty-five native Dutch-speaking adults aged 60 to 73 completed a connected speech network task in which lexical frequency (high vs. low) was manipulated. Disfluencies occurring during picture naming were annotated and analyzed using generalized linear mixed-effects models. Lexical frequency did not significantly influence the overall likelihood of disfluency production. However, low-frequency words were associated with a significantly higher likelihood of producing semantic paraphasias and semantically related answers and a reduced likelihood of additions. Correlational analyses further revealed that participants with higher vocabulary scores produced fewer semantic disfluencies, indicating a protective role of lexical knowledge in aging. The findings underscore the importance of differentiating disfluency types and considering task-specific characteristics when investigating language production in older adults. By focusing on connected speech and isolating word-form retrieval demands, this study contributes to a more nuanced and refined understanding of age-related disfluency patterns. Implications are discussed in relation to “good-enough language production”, inhibitory control mechanisms, and the methodological challenges of capturing language production difficulties in cognitively demanding but ecologically valid tasks and contexts.
Römkens et al. (Tue,) studied this question.