biology question #2161



Stanley, a 16 year old male from Vancouver asks on June 30, 2004,

Q:

Why are soccer balls coloured black and white? I heard it has to do with these two colours making the ball easier to see during daytime and nightime. Can you please explain how these colours help to make the ball easier to see?

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the answer

Barry Beyerstein answered on July 16, 2004, A:

This is not a scientific answer, but rather a guess based on related science. I'd be surprised if the soccer officials set out with scientific principles in mind when they came up with the currently-accepted design for the regulation ball, but if indeed it was luck, they stumbled onto a pretty good solution. Having alternating black and white panels in the ball makes sense for a number of reasons, given how the visual system works.

First, black and white provide the maximum possible contrast for the eye. When such a ball rotates in the air, it creates a sort of flicker which the eye is particularly sensitive to, especially in peripheral vision. The ability to catch something "in the corner of your eye" must be very valuable when you need to also be watching in front of you and what's going on down the field too, and still "keep your eye on the ball". Also, alternating black and white panels provide many sharp-edged, high-contrast contours. There are cells in the brain that are tuned to respond maximally to those edges, especially if they are moving, and the visual system accentuates these details because that's where the maximum useful information is. Hence, it makes the ball more visible on that count too.

In the periphery of our visual field, we are maximally sensitive to flicker and motion (less so to fine detail and not at all to colour), so this kind of design would be a more noticeable stimulus for players. In the periphery, we have no colour vision, so alternating colored panels could well produce none of that very useful flicker or edge stimulation -- i.e., if the colours were different, but their relative brightness were the same, there would be no visual contrast for the eye to detect.

Finally, if the ball were coloured, as opposed to black and white, it would probably blend in better with player's uniforms, the grass, ads on the side of the soccer pitch, the clothing of the people in the stands, etc., -- a sort of camouflage effect, making it harder to pick out from the background if the player were looking directly at the ball with the fovea of the eye, which contains all the cones (colour receptors).

Because so much good play in soccer depends on keeping track of things going on in the periphery of vision, I suspect that making the ball maximally detectable to perpheral parts of the retina pays more dividends in the long run than making it highly detectable to the central, colour sensitive part of the eye, which will pick it up no matter what, if you're looking right at it.

As for dark adaptation (assuming they play under darker conditions), sensitivity to colour diminishes when we become dark adapted, and sensitivity to certain wavelengths is particularly diminished. So a ball of that colour would then be harder to detect, even in the central portion of the visual field if things get dim.

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