Trading Accuracy for Fluency? An investigation of word retrieval difficulties in connected speech

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.