G'morning Paul, 

 HT> The cones that allow us to see
 HT> color cannot identify the actual wavelengths that hit them,
 HT> but if they are stimulated by the right combination of
 HT> wavelengths, then it will appear the same to our eyes as a
 HT> single pure color, or a mixture of a pure color and white
 HT> light.  (Smith, American Journal of Physics, July 2005)

 PR> Color perception is more complex than that, c.f. Land Effect,
 PR> as in Edwin Land of Polaroid Camera fame.

And the black & white colour-producing disk based upon it.

I was last month measured up for a cataract operation by a laser 
driven device that precisely measured the crippled eye;  it left 
me in the grip of a dazzlingly different figural affer-effect - an 
array of sizzling colours being teh complement of light I'd never 
encountered before....

Indeed,  every perceptual effect turns out, when probed, to be far 
more complex than is spelt out in the 101 texts....

:-)
 
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