Contrast
The pioneers of readability studies were obviously only dealing with printed text. However, by the end of the 1960s, computers with led screens had become relatively mainstream. Due to their inherent properties, they turned out to be more demanding on the eye.
Glowing screens make the reading experience physically different from a paper that only reflects light—the higher the brightness level, the stronger the effect. “If you set the brightness up much too high, a direct focus of light will come into your retina, causing fatigue,” explains Nick Sherman, a typographic consultant and the founder of hex projects typographic company.
