Individual differences and their effect on the nature of speech motor errors in younger and older adults

Abstract

Older adults have been reported to have a greater propensity towards speech errors [MacKay & James, Psych & Aging, 19(1), 93–107 (2004)],but as with many age-related effects, there is considerable variability in results and a need to identify behavioral predictors. The present study employs a motor speech paradigm, whereby both younger and older adults repeated word pairs (e.g., “top-cop”) timed to a metronome in an accelerating rate task. The metronome had a steady rate for half the task (8s) and then increased at a linear rate. Participants also completed evaluations of motor speech, sensory, and cognitive abilities, so that these individual characteristics can be correlated with speech error tendencies. Articulatory data of speech movements were collected in the form of ultrasound tongue contours and lip aperture derived from facial video. Articulatory results are discussed in terms of speech error gradience in the context of previous work [Pouplier, Proc. XVth ICPhS, 2245–2248 (2003)], with emphasis on how well speakers adapt to the changing metronome rate, and how this affects error incidence in younger versus older adults.