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Marcia Bécu, Guillaume Tatur, Annis-Rayan Bourefis, Luca Bologna, Denis Sheynikhovich, Angelo Arleo; Age-related changes in gaze dynamics during real-world navigation. Journal of Vision 2017;17(10):540. doi: https://doi.org/10.1167/17.10.540.
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Healthy aging is associated with changes in the way people navigate in space. However, little is known about the impact of aging on eye movements mediating the exploration and acquisition of spatial information. This study investigated how aging shapes the oculomotor dynamics during goal-oriented navigation in real environments. Twenty young (µ=26 y/o, σ=5.06) and 20 old (µ=72 y/o, σ=4.22) subjects were ascertained to be healthy by visual, vestibular, oculomotor, and cognitive screening. Then, they were requested to solve a spatial navigation task by finding an invisible goal in a real environment (a 8.6x4.3 m street-like setup made of realistic relief sceneries). Subjects were disoriented at the beginning of each trial. After training (8 trials), the whole configuration of landmarks was rotated, creating a conflict between the landmarks and the geometry of the environment (5 probe trials). Eye and full body movements were recorded throughout the experiment. We found that older subjects took on average more time to reach the goal, due to a larger decision time during reorientation, suboptimal spatial navigation, and lower walking speed. Interestingly, compared to young subjects, a greater proportion of older adults reoriented according to a geometry-based strategy during probe tests, neglecting landmarks rotation. This came at a cost in terms of optimality of the trajectory employed. Gaze fixation characteristics (e.g., frequency, duration) as well as eyes/head coordination and general sensorimotor abilities did not differ with age. However, in older adults fixations were significantly more exploitative (looking at the same landmark) than explorative (searching for a new landmark). Also, older adults more often revisited previously fixated landmarks across a same trial. In conclusion, analyzing the time course of eye movement signatures in real-world spatial tasks helped unveiling and understanding age-related differences in spatial coding and goal-oriented navigation strategies.
Meeting abstract presented at VSS 2017
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