Stripes and Greys
Grey bars woven into black and white stripes, two ways.
How to play
Look first, then answer
Grey bars woven into black and white stripes, two ways.
- Under a minute · one question · then the explanation
How it works — best read after you have tried it
Belonging beats bordering
Every grey bar is the same grey. The bars on the left usually look lighter, even though most of their border is white — which is the opposite of what simple contrast with the neighbouring edges predicts.
What seems to decide it is which stripe a bar belongs to: it is read as part of the stripe it lies in and compared with that. Michael White described the effect in 1979, and it is a standing puzzle for any theory that explains lightness by edges alone.