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Physiological

Simultaneous Brightness Contrast

Surround-Dependent Luminance Induction • Two identical gray target boxes appear drastically different depending on surround luminance.

Parameter Controls

Adjust procedural mathematical parameters in real-time to alter or break the illusion.

Target Inner Gray Shade #808080
Left Background Shade #1e293b
Right Background Shade #f1f5f9
Inner Square Size (px) 60

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🧠 Scientific Explanation & Psychophysics

Underlying Mechanism: Retinal Lateral Inhibition & Center-Surround Antagonism

Retinal ganglion cells with center-surround receptive fields register relative contrast rather than absolute brightness. Dark surrounds cause less lateral inhibition to ganglion cells processing the inner box (making it look brighter), whereas light surrounds trigger strong lateral inhibition (making it look darker).

Why This Works in the Brain

The visual cortex processes incoming sensory information using specialized receptive fields and cortical feature detectors. Illusions occur when mathematical geometries produce conflicting spatial signals, exposing how the brain constructs subjective perception from objective electromagnetic light waves.

💬 Community Notes & Observations

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