Discourse Production Across the Adult Lifespan: Microlinguistic Processes

Area of Science:

• Linguistics
• Psychology
• Neuroscience

Background:

• Spoken discourse informativeness relies on lexical diversity, core lexicon, and information units.
• Older adults often produce less informative discourse, though lexical diversity changes are subtle.
• The trajectory of core lexicon typicality in healthy aging remains understudied.

Purpose of the Study:

• To investigate age-related changes in microlinguistic processes of discourse informativeness.
• To analyze how lexical diversity, core lexicon, and information units evolve across the adult lifespan.

Main Methods:

• Cross-sectional study of 420 healthy adults aged 20-89.
• Analysis of narrative language samples from wordless picture books.
• Quantification of lexical diversity (LD), percent correct information units (%CIUs), and core lexicon (CL) nouns and verbs.

Main Results:

• Percent correct information units (%CIUs) and core lexicon (CL) nouns showed a quadratic decline starting around ages 40 and 60, respectively.
• Lexical diversity (LD) exhibited a slight linear decline with age.
• Core lexicon (CL) verbs were stable with age but influenced by education.

Conclusions:

• Discourse informativeness shows varied age-related trajectories, with some aspects declining (e.g., %CIUs, CL nouns) and others remaining stable (e.g., CL verbs).
• Differential changes in informativeness measures may stem from language system connectivity and measure characteristics.
• Findings systematically map the aging trajectory of discourse informativeness variables.