Oct 5, 2026 · 30 min
The brain decides whether tennis balls look yellow or green
What color is a tennis ball?
The tennis-ball dispute reveals how perception, language, culture, and experience shape what people treat as shared visual reality.
- 1Color perception depends on high-level brain processing, not wavelengths alone or properties fixed entirely in objects.
- 2Color constancy helps the brain perceive stable objects across changing light, but assumptions can still split perception dramatically.
- 3Language, culture, object statistics, and artistic practice influence where people draw boundaries between colors such as blue, green, orange, and brown.
Don't miss
Bevil Conway explains why a fluorescent tennis ball can legitimately appear both greenish and yellowish, depending on how color categories are constructed.
The brief
A disagreement over whether tennis balls are yellow or green opens a larger question: is color a property of objects, or a judgment constructed by the brain?
Neuroscientist and artist Bevil Conway explains color constancy, the brain’s effort to keep objects looking stable as illumination changes, and why wavelength alone cannot settle what color is.
The viral blue-and-black or white-and-gold dress shows how assumptions about lighting can produce radically different perceptions—and make shared reality feel less secure.
Returning to tennis balls, Conway argues that their bright fluorescent appearance carries both greenish and yellowish qualities, while people vary in how they categorize colors.
Language, culture, experience, and object statistics help define color boundaries; Conway’s painting turns that constructed quality into an artistic and communicative resource.
Featuring
Bevil Conway
National Eye Institute
Henri MatisseBooks & mentions
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