Effects of Word Order Canonicity on Online Self-paced Reading Processing in Older Adults

Objectives: There is debate about whether sentence processing abilities decline with age in older adults, or if they remain relatively intact. In contrast to the numerous studies on English-speaking populations, little research has been conducted on the real-time sentence processing abilities of Korean-speakers. This study aims to explore the effects of word order canonicity on the real-time sentence processing abilities of older adults using center-embedded sentences with subject-relative clauses. Methods: A total of 42 participants, 21 young and 21 older adults, participated in a self-paced reading paradigm involving complex sentences with subject-relative clauses. Participants read the sentences and subsequently judged related statements. Additionally, reading times for each segment of the complex sentences were recorded to determine where sentence information was integrated. Results: Older adults showed significantly lower accuracy and longer response times in judgment statements compared to younger adults. The response times exhibited significantly greater differences between the two groups in noncanonical word order sentences than in canonical ones. Additionally, older adults had significantly longer online reading times in both canonical and noncanonical word orders compared to younger adults, with notable differences in the regions of the subject-relative clause and the noun phrase modified by the subject-relative clause. Conclusion: Older adults struggle more with sentence both offline and online compared to younger adults, especially with noncanonical word orders due to higher cognitive loads. Their longest reading times occurred in noun phrases modified by subject-relative clauses, supporting the role of working memory in real-time processing.