Size matters (spacing not): 18 points for a dyslexic-friendly Wikipedia

In 2012, Wikipedia was the sixth-most visited website on the Internet. Being one of the main repositories of knowledge, students from all over the world consult it. But, around 10% of these students have dyslexia, which impairs their access to text-based websites. How could Wikipedia be presented to be more readable for this target group? In an experiment with 28 participants with dyslexia, we compare reading speed, comprehension, and subjective readability for the font sizes 10, 12, 14, 18, 22, and 26 points, and line spacings 0.8, 1.0, 1.4, and 1.8. The results show that font size has a significant effect on the readability and the understandability of the text, while line spacing does not. On the basis of our results, we recommend using 18-point font size when designing web text for readers with dyslexia. Our results significantly differ from previous recommendations, presumably, because this is the first work to cover a wide range of values and to study them in the context of an actual website.