Priti Gupta¹ (), Stutee Narang¹, Purva Sethi¹, Shraddha Sharma¹, Naviya Lall¹, Meghna Rao¹, Manvi Jain¹, Chetan Ralekar², Lukas Vogelsang², Marin Vogelsang², Michal Fux², Suma Ganesh², Pawan Sinha²; ¹Project Prakash, Dr Shroff's Charity Eye Hospital, New Delhi, India, ²Department of Brain and Cognitive Sciences, MIT, USA

The human visual system is exquisitely sensitive to bilateral vertical symmetry. Although the roots of this proficiency are not definitively known, they may relate to the kinds of regularities present in ecologically important entities such as animals, faces, and plants. Even neonates are reported to exhibit sensitivity to vertical symmetry, suggesting that visual experience may play only a limited, if any, role in the genesis of this ability. Against this backdrop, here we ask whether the perception of bilateral symmetry is resilient to severe restrictions of early visual experience. To this end, we worked with children who had early onset blindness and received sight surgeries at the age of several years. We recruited two patient groups. The first (n = 15, mean age = 16.4y) had their sight surgeries two to four years prior to this study and therefore had had a significant period of visual experience post-surgery. The second group (n=5, mean age = 12.6y) was newly operated and had only had upto fourteen months of visual experience. The performance of these two patient groups was compared with controls (n=13, mean age = 17.2y). Our stimulus images comprised ten colored discs arranged in a vertically symmetric or non-symmetric configuration. Results reveal a significant compromise in symmetry-based classification across newly-sighted patients. For patients who had long periods of visual experience post their surgery, symmetry-based classification improves but does not reach control level. In summary, the data thus far indicate a profound role of early visual experience on symmetry perception and, perhaps, long-range visual analyses more broadly.

Acknowledgements: We are grateful to NIH for supporting this work