Overview

In the summer of 1997, I designed an experiment to measure human ability to trace paths between connected parts in a 3D diagram. Then, as is my normal practice, I ran a pilot study in order to see whether the experiment was well constructed. By ill luck, the first person tested was a research assistant who worked in my lab. He had far more difficulty with the task than anticipated so much so that I put the experiment back on the drawing board to reconsider, without trying any more pilot subjects. Some months later, my assistant told me he had just had an eye test and the optometrist had determined that he was color-blind. This explained the problems with the experiment. Although it was not about color perception, I had marked the targets red in my experiment and he therefore had had great difficulty in finding them, which rendered the rest of the task meaningless.

The remarkable aspect of this story is that my assistant had gone through 21 years of his life without knowing that he was blind to many color differences. This is not uncommon and it strongly suggests that color vision cannot be all that important to everyday life. In fact, color vision is irrelevant to much of normal vision. It does not help us determine the layout of objects in space, how they are moving, or what their shapes are. It is not much of an overstatement to say that color vision is largely superfluous in...