In a study published in 1992, scientists flashed a pattern on a video monitor: a 30-by-30 grid of small rectangles, all of them oriented vertically except within a randomly located 7-by-7 "target area" where the rectangles were horizontal. Test participants were asked to press one of four buttons to indicate what quadrant of the screen the target area had appeared in. Some test participants had normal color vision, while others, so-called dichromats (I'll explain below), had severe colorblindness rendering them incapable of distinguishing red from green.
In the first trial, all the rectangles were the same color, and participants in both groups had little difficulty spotting the target. In the next trial, the rectangles were randomly colored red or green. This time around, those with normal color vision did poorly — all they saw in the brief time the pattern appeared (a fifth of a second) was a jumble of red and green.
The dichromats, on the other hand, kicked butt. Without color to distract them, they spotted the target as easily as with a monochrome pattern. The same held true when each target rectangle was replaced with a capital A while the background rectangles were replaced with Bs. Despite this conspicuous difference, randomly coloring the letters red or green completely flummoxed those with normal color vision. The dichromats, on the other hand, were unperturbed, picking out the target as effortlessly as before.
