Re: Be careful about differentiating by colour
Just look at a "green" traffic light. We all call it green, but it's not actually really green is it? Because if it was then 10%-15% of the population would not be able to tell it apart from red, other than by its position.
I remember a Usenet discussion on colour blindness and traffic lights. One contributor who was colour blind said that to him traffic lights were grey, yellow and white, and it was the position he went by.