The ability to speak coherently is essential for effective communication but declines with age: older people more frequently produce tangential, off-topic speech. The cognitive factors underpinning this decline are poorly understood. We predicted that maintaining coherence relies on effective regulation of activated semantic knowledge about the world, and particularly on the selection of currently relevant semantic representations to drive speech production. To test this, we collected 840 speech samples along with measures of executive and semantic ability from 60 young and older adults, using a novel computational method to quantify coherence. Semantic selection ability predicted coherence, as did level of semantic knowledge and a measure of domain-general executive ability. These factors fully accounted for the age-related coherence deficit. Our results indicate that maintaining coherence in speech becomes more challenging as people age because they accumulate more knowledge but are less able to effectively regulate how it is activated and used.
All raw data and code required to replicate the analyses are available at https://osf.io/8atfn/DOI 10.17605/OSF.IO/8ATFN
- Paul Hoffman
- Paul Hoffman
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: All participants provided informed consent and the study was approved by the University of Edinburgh Psychology Research Ethics Committee.(120-1415/3).
- Elizabeth Jefferies, University of York, United Kingdom
© 2018, Hoffman et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.