Visual Perception for Fun

Don't I see red and you see blue and we call it green as we told to do?

At this time of year I often find myself embroiled in family dinner conversation. In my family someone will bring up, one of the old classics thought puzzles normally in an effort to steer the conversation away from the same old same old - money, religion and morality trench. Last night was no exception and I was delighted again to hear the re-discussion of such a classic puzzle.

Do we all see red or do we have a random conditioned - name - allocated to a particular frequency of light - red in this case, irrespective of how it appears to us. The argument normally ends in the typical line - well, it's impossible to know.

This morning I thought I would examine the claim for fun.

So red (400–484 THz) hits the retina cones, each "tuned" to respond best to light from a portion of the spectrum of visible light (red, green and blue). In this case long-wavelength of light = red. Then it’s off to the brain for interpretation.   Well, that's the mechanics of the visual system. The last step of - Visual Perception (for the sake of shorthand - VP) is called into question.

Now on face value, in a mechanical sense the two properly functioning eyes and brains, should see the same thing. Just as we would expect two properly functioning cameras to record the same info. Why question the VP process?

Well, it seems to me,  it has to do with the notion of certainty of induction. How certain are you that VP is the same in regard to colour? This would lead to a probability (P) formula - If P(A) > P(B) then event A  is more likely to occur than event B. So on this view multiple properly functioning visual system have a greater probability in regard to VP being the same. This is not to say that it is 100% certain. Such certainty does not exist in inductive argument. Therefore, it seems to me, one may well expect some variation in saturation, sharpness and range in regard to VP, but this is not equivalent of long-wavelength (red) being mistakenly construed as short-wavelength light (blue). 

Deductively it follows:

1 All properly functioning visual system respond to light in the same way
2 People have such properly functioning visual system
3 Therefore, people with properly functioning visual system respond to light in the same way


In conclusion, colour is not merely about wavelength and synapse. Visual Perception is a very
complex subject, but for party conversation this will mix it up a bit.

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