The Relationship between Eye Movements and Audiovisual Time-to-Contact Estimates in Young and Old Adults

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2024-12-04
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Introduction: This dissertation investigated how saccadic eye movements, aging, and central vision loss affect time-to-contact (TTC) estimates in a dynamic, traffic-related environment. The goal was to explore the role of eye movement behaviors and sensory integration across different adult populations, including younger adults, older adults, and individuals with age-related macular degeneration (AMD), in both visual and audiovisual contexts. Method: Two experiments were conducted. In Experiment 1, participants completed TTC tasks in visual-only and audiovisual conditions; half of them were instructed not to make saccadic eye movements. Experiment 2 examined TTC estimates and eye movement behaviors in younger and older adults, as well as individuals with AMD and older adults with normal vision, in both visual and audiovisual modalities. Results: In Experiment 1, individuals who made saccadic eye movements had significantly higher TTC estimates in the visual-only modality than in the audiovisual condition. However, individuals who did not make saccadic eye movements had similar TTC estimates in the visual-only and audiovisual modalities. In Experiment 2, older adults exhibited shorter fixation durations compared to younger adults, and their longer fixations led to greater underestimations of TTC, which resulted in safer judgments. Individuals with AMD had less stable eye movements than older adults with normal vision but they made more accurate TTC estimates in the audiovisual condition compared to the visual-only condition, indicating a reliance on auditory cues to compensate for visual deficits. Conclusion: These findings reveal that eye movements affect TTC judgments when information is presented visually but not when both auditory and visual stimuli are presented. Aging and central vision loss alter the relationship between eye movements and TTC judgments. Older adults with normal vision and adults with central vision loss underestimated TTC when they made longer fixations, suggesting that the relationship between TTC estiamtes and eye movements changes as a result of age and visual abilities.

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Doctor of Philosophy
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Time-to-contact, Eye Movements, Aging
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