Felicia Tassone¹ (), Zoha Ahmad¹, Tzvi Ganel², Erez Freud¹; ¹York University, ²Ben-Gurion University of the Negev

According to the two visual pathways hypothesis, vision-for-perception and vision-for-action are mediated by different neural pathways. While this dissociation has been well-studied in younger adults using psychophysics and neuroimaging, it is unclear whether healthy aging modulates the dissociation across the lifespan. To bridge this gap, we examined the effect of aging on visuomotor and perceptual tasks in two experiments, both completed by older (n = 26, range: 60–95 years) and younger adults (n = 26, range: 18–25 years). Experiment 1 aimed to test for potential differences among perceptual and visuomotor sensitivity to object size using “Efron blocks”, which vary in width and length but have an identical surface area. In the two conditions, participants were asked to perceptually estimate the width of the blocks using their fingers or to grasp the objects across their width. Experiment 2 utilized the Ponzo illusion to explore potential differences in the dissociation between perception and visuomotor control between younger and older adults. Participants completed the perceptual and grasping conditions with objects placed on the “close” and “far” surfaces of the illusion. The results of Experiment 1 showed an age-related decrement in size sensitivity, which was more strongly evident in the grasping task. In Experiment 2, both groups demonstrated a dissociation between perception and action, such that greater perceptual estimations were observed when objects were placed on the “far” surface of the illusion, while this effect was not observed during the grasping task. Unexpectedly, older adults even exhibited a reversed effect during grasping, with larger apertures for objects placed on the “close” surface. These findings suggest that while visuomotor abilities decline with age, the dissociation between perception and action is largely preserved.

Acknowledgements: Natural Sciences and Engineering Research Council of Canada (NSERC); CFREF's "Vision: Science to Applications" (VISTA)