I've given that a bit of thought.

The tests we use to determine animals vision may indeed measure their sensitivity to certain wavelengths of light, but I think many animals still perceive these wavelengths in other ways.

If a spectrum is out of the range of the rods and cones, other centers of the brain may react to these subharmonic wave signals present and embedded on the waves of light they do perceive.

The common consensus is that bulls are color blind, but I suspect it's not just the motion of the red cape that attracts them. It may be possible that they sense colors in absentia - or in other words, the light waves perceived still carry their payload to centers of the brain where a difference is noted between the apparent shades of gray.

One intensity of gray would not be just like another.

Since the human eye catches the red wavelength first because of it's length, it seems feasible even colorblind animals could be agitated by red, even when they can't see it because their brain stores the signals differently.

I know, It's confusing.

I'm still not giving back the quarter, Bugs Meany!

Oh wait...I waived that fee.

Nevermind.

;-)