If you’re human, this sentence is probably hard to read.
If you’re human, this sentence is probably not hard to read.

Humans can’t perceive detail and blue at the same time. Our eyes aren’t engineered for it.

We perceive detail at the center of our visual field. The eye’s light- and color-sensitive cells, called cones, are packed most densely at the fovea, the center of the retina. (The retina has more pixels per inch at its center, if you like.) We distinguish shades of blue wherever we have “blue” cones, the one of our three types of cones most selective for blue colors.

To read blue, we need to perceive detail and shades of blue at once. Except we can’t. There are no blue cones in the fovea.

If you can’t read the words below, there’s nothing wrong with you. You’re just human. If only the software and web designers understood.

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