Gaze following requires early visual experience

Ehud Zohary*, Daniel Harari, Shimon Ullman*, Itay Ben-Zion, Ravid Doron, Sara Attias, Yuval Porat, Asael Y. Sklar, Ayelet McKyton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Gaze understanding-a suggested precursor for understanding others' intentions-requires recovery of gaze direction from the observed person's head and eye position. This challenging computation is naturally acquired at infancy without explicit external guidance, but can it be learned later if vision is extremely poor throughout early childhood? We addressed this question by studying gaze following in Ethiopian patients with early bilateral congenital cataracts diagnosed and treated by us only at late childhood. This sight restoration provided a unique opportunity to directly address basic issues on the roles of “nature” and “nurture” in development, as it caused a selective perturbation to the natural process, eliminating some gaze-direction cues while leaving others still available. Following surgery, the patients' visual acuity typically improved substantially, allowing discrimination of pupil position in the eye. Yet, the patients failed to show eye gaze-following effects and fixated less than controls on the eyes-two spontaneous behaviors typically seen in controls. Our model for unsupervised learning of gaze direction explains how head-based gaze following can develop under severe image blur, resembling preoperative conditions. It also suggests why, despite acquiring sufficient resolution to extract eye position, automatic eye gaze following is not established after surgery due to lack of detailed early visual experience. We suggest that visual skills acquired in infancy in an unsupervised manner will be difficult or impossible to acquire when internal guidance is no longer available, even when sufficient image resolution for the task is restored. This creates fundamental barriers to spontaneous vision recovery following prolonged deprivation in early age.

Original languageAmerican English
Article numbere2117184119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
StatePublished - 17 May 2022

Bibliographical note

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  • blind
  • cataract
  • gaze
  • joint attention
  • vision


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