What Eye Movement Reveals Concerning Age-Related Dissociation in Syntactic Prediction: Evidence From a Verb-Final Language

Purpose: How older adults engage in predictive processing compared to young adults during sentence processing has been a controversial issue in psycho-linguistic research. This study investigated whether age-related differences in predictive processing emerge and how they influence young and older adults' construction of sentential representations in a verb-final language using the visual world eye-tracking paradigm. Method: Twenty-five young adults and 24 older adults participated in this study. They were administered a sentence-picture matching task under active and passive conditions during which their eye movements were recorded. Results: Older adults showed a stronger reliance on predictive processing based on probabilistic constraints compared to young adults at the second noun phrase (NP2) for both active and passive sentences. Specifically, older adults showed significantly greater target advantage looks in actives but greater distractor advantage looks in passives before encountering the verb compared to young adults, revealing older adults' stronger preference for active sentence representations. This stronger predictive processing at the NP2 among older adults engendered greater reduction in fixation proportion on the target picture at the verb only under the passive condition, suggesting that older adults experienced greater difficulties with syntactic revision and integration in passives compared to young adults. Conclusion: The current findings support that older adults more strongly rely on predictive processing based on probabilistic constraints denoted by case markers when constructing sentential representation compared to young adults, and this processing pattern increases processing difficulties when their prediction is incongruent with linguistic input.