Disfluency across the lifespan: an individual differences investigation.

This study had two research objectives. The first was to examine age-related differences in the fluency of speech outputs, as prior research contains conflicting findings concerning whether older adults produce more disfluency than younger adults. The second was to examine cognitive individual differences, and their relationship with the production of disfluency. One hundred and fifty-four adults completed a story re-telling task, and a battery of cognitive measures. Results showed that younger adults produced more um's and fewer repetitions. For individual differences, results showed that inhibition and set shifting were related to the production of repetitions, and inhibition and working memory were related to uh production. Our results provide clarification about mixed findings with respect age and disfluency production. The individual differences provide clarification on theoretical arguments for disfluent speech in aging (e.g. Inhibition Deficit Hypothesis), and also sheds light on the role of executive functions in models of language production.