[notfed]

I'm still not convinced. They said the answer is pink. But...it wasn't pink, even to their own admission. A pink shoe, when placed under pure-green lighting is no longer pink: at this point we're out of illusion territory and into lighting trick / semantics territory.

If they'd have said the answer is green-gray, then fine, this would be an illusion for those people who incorrectly thought the shoes are pink, but their answer is still wrong.

[krsrhe]

The picture is gray, but the actual shoes are pink, but bathed in green light. Some people sometimes can mentally remove the green lighting.

[dsr_]

To do this properly, then, they should use video instead of stills.

Have a nice white background. White socks, pink shoes. Slowly move a green spotlight across the scene.

[drdec]

This is what I don't understand. I thought the socks were green, not white in green light, and still thought the shoes were pink.