Syntactic flexibility and lexical encoding in aging sentence production: an eye tracking study

TL;DR

This study explores how aging affects the process of sentence production, focusing on lexical encoding and syntactic structure.

Contribution

The study introduces new insights into how aging impacts real-time lexical encoding and syntactic flexibility during sentence production.

Findings

Older adults showed comparable syntactic flexibility to younger adults in sentence production.

Older adults exhibited prolonged lexical encoding effects during early sentence planning stages.

Reduced verbal working memory may contribute to age-related changes in lexical encoding.

Abstract

Successful sentence production requires lexical encoding and ordering them into a correct syntactic structure. It remains unclear how different processes involved in sentence production are affected by healthy aging. We investigated (a) if and how aging affects lexical encoding and syntactic formulation during sentence production, using auditory lexical priming and eye tracking-while-speaking paradigms and (b) if and how verbal working memory contributes to age-related changes in sentence production.

Twenty older and 20 younger adults described transitive and dative action pictures following auditory lexical primes, by which the relative ease of encoding the agent or theme nouns (for transitive pictures) and the theme and goal nouns (for dative pictures) was manipulated. The effects of lexical priming on off-line syntactic production and real-time eye fixations to the primed character were measured.

In offline production, older adults showed comparable priming effects to younger adults, using the syntactic structure that allows earlier mention of the primed lexical item in both transitive and dative sentences. However, older adults showed longer lexical priming effects on eye fixations to the primed character during the early stages of sentence planning. Preliminary analysis indicated that reduced verbal working memory may in part account for longer lexical encoding, particularly for older adults.

These findings indicate that syntactic flexibility for formulating different grammatical structures remains largely robust with aging. However, lexical encoding processes are more susceptible to age-related changes, possibly due to changes in verbal working memory.

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