When I was about seven, in the days when color television wasn’t a given in every household, I was thrilled one Saturday morning to see pale colors emerging from the new tv set my parents had brought home.  Cartoons would be more fun!  I mentioned this to my parents, who were surprised:  the new tv set was black and white.  My parents quickly figured out that I was colorblind and was mistaking shades of grey for color.  Still, I felt fine, and I insisted that I could see color in that set.  Obviously it was my parents who had impaired vision. After all, they wore glasses.