[J_McQuade]

I tried covering up bits with my hand, with bits of paper, and staring at it with varying intensities - I still didn't believe it until I loaded it up in Gimp and checked the colour values.

It seems our perception of colour could be like our perception of temperature - comparative, rather than 'quantitative' in any way. Anyone here know of any studies into this?

[evanrmurphy]

I even got suspicious that the right image on the Proof page might have been doctored, but it does pass the Gimp test. :)

[JoeAltmaier]

Make a little circle with your index fingers and thumbs, put it over each square, that breaks the spell.

[TheTarquin]

An interesting idea. This would put it in the same class as a remarkably large number of emergent "senses" like our sense of distance or of weight, which are both effected by ancillary information.