Tracking Talking: Dual Task Costs of Planning and Producing Speech for Young versus Older Adults

ABSTRACT

A digital pursuit rotor was used to monitor speech planning and production costs by time-locking tracking performance to the auditory wave form produced as young and older adults were describing someone they admire. The speech sample and time-locked tracking record were segmented at utterance boundaries and multilevel modeling was used to determine how utterance-level predictors such as utterance duration or sentence grammatical complexity and person-level predictors such as speaker age or working memory capacity predicted tracking performance. Three models evaluated the costs of speech planning, the costs of speech production, and the costs of speech output monitoring. The results suggest that planning and producing propositionally dense utterances is more costly for older adults and that older adults experience increased costs as a result of having produced a long, informative, or rapid utterance.

Keywords:

• Aging
• Speech production
• Speech planning
• Dual task demands
• Fluency

ACKNOWLEDGEMENTS

Susan Kemper, Department of Psychology and Gerontology Center, University of Kansas; RaLynn Schmalzried, Department of Psychology, University of Kansas; Lesa Hoffman, Department of Psychology, University of Nebraska-Lincoln; Ruth Herman, Gerontology Center, University of Kansas; Doug Kieweg, Center for Biobehavioral Neurosciences in Communication Disorders, University of Kansas. Preliminary results were presented at the 2010 Cognitive Aging Conference in Atlanta. This research was supported in part by grants from the NIH to the University of Kansas through the Mental Retardation and Developmental Disabilities Research Center, grant number P30 HD-002528, and the Center for Biobehavioral Neurosciences in Communication Disorders (BNCD), grant number P30 DC-005803 as well as by grant RO1 AG-025906 from the National Institute on Aging to Susan Kemper. Its contents are solely the responsibility of the author and do not necessarily represent the official views of the NIH. We thank Shalyn Oberle, Deepthi Mohankumar, and Whitney McKedy for their assistance with data collection and analysis. A suite of digital pursuit rotor applications is available upon request.

Notes

¹Pursuit rotor tracking has long been used as a measure of skill acquisition and perceptual-motor learning and has more recently been used to assess the effects of age differences in working memory and other cognitive resources on skill acquisition (Ghisletta, Kennedy, Rodrigue, Lindenberger, & Raz, 2010). Traditionally, time on target (TOT) is used as the critical measure of performance: participants are required to keep a wand or other device in contact with a rotating target and the percentage of time contact is maintained is determined. The use of a digital pursuit rotor permits a second measure of tracking performance to be determined: tracking error (TE). Participants may abandon tracking, resulting in large TE, or they may lag somewhat behind the target, resulting in smaller TE. Hence, the comparison of TOT and TE may reveal the use of different strategies in response to varying task demands. In addition, the digital pursuit rotor also permits measures of TOT and TE variability to be computed and these measures may also be informative as to the sources of group and individual differences in tracking performance.