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Seeing in the dark: High-order visual functions under scotopic conditions
Ayelet McKyton1, Deena Elul1,2, Netta Levin1
1fMRI Unit, Department of Neurology, Hadassah Medical Organization and Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
Iscience
|February 7, 2024
Summary
People can read and recognize faces in near darkness using rod photoreceptors (scotopic vision). Surprisingly, visual attention remains central, suggesting global perception guides vision in low light.
Area of Science:
- Vision Science
- Neuroscience
- Perception
Background:
- Visual function in near-complete darkness (scotopic conditions) is poorly understood.
- Rod photoreceptors are primarily active during scotopic vision, mediating low-acuity vision.
Purpose of the Study:
- To investigate visual acuity, crowding, and high-level visual tasks under scotopic conditions.
- To determine if central fixation is maintained for complex tasks in low light.
Main Methods:
- Tested scotopic visual acuity and crowding at varying retinal eccentricities.
- Recorded eye movements during reading and face perception tasks under photopic and scotopic conditions.
Main Results:
- Demonstrated a foveal scotoma and increased crowding with eccentricity, with optimal discrimination 2° into the periphery.
- Participants accurately read text and exhibited a face inversion effect under scotopic conditions.
- Eye movements revealed longer fixation durations and central fixation, similar to photopic conditions, correlating with global perception.
Conclusions:
- High-level visual tasks like reading and face perception are possible under scotopic conditions.
- Central fixation and global perception appear to govern visual processing even in near-complete darkness.
- Receptive-field properties may explain the dominance of global perception in scotopic vision.
Keywords:
Biological sciencesCognitive neuroscienceNatural sciencesNeuroscienceSensory neuroscienceSystems neuroscienceMore Related Videos
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