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Attention can shift the reference eye under binocular fusion failure: A case report
Jiahao Wu1,2, Tengfei Han1,3, Qian Wang4,5
1National Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China.
Journal of Vision
|December 17, 2025
Summary
When binocular fusion fails, the brain adapts by using a single eye as a reference frame. This study shows this adaptation can be flexibly controlled by attention, even after vision loss.
Area of Science:
- Neuroscience
- Ophthalmology
- Visual Perception
Background:
- Binocular fusion integrates visual input from both eyes into a single percept via a "cyclopean eye."
- The spatial reference frame used when fusion fails is not well understood.
Purpose of the Study:
- To investigate the spatial reference frame utilized when binocular fusion breaks down.
- To explore the role of attention in adapting visual perception after fusion failure.
Main Methods:
- Case study of a patient with diplopia after cerebellar surgery.
- Clinical assessment of extraocular muscle function.
- Experimental evaluation of binocular and dichoptic viewing conditions.
Main Results:
- The patient's perception was consistently anchored to the left eye, with the right eye's image misaligned.
- Monocular viewing did not result in diplopia.
- The patient could voluntarily switch the reference eye, independent of stimulus characteristics or task demands.
Conclusions:
- Following breakdown of cyclopean fusion, visual perception defaults to a single-eye reference frame.
- Attentional control can flexibly influence the chosen eye's reference frame in binocular vision.
- This case highlights the interplay between automatic sensory processing and top-down control in vision.
