Internal Validity in Experiments for Typefaces for People with Dyslexia


In recent years, designers claim to have created typefaces that help people with dyslexia, but what evidence supports these claims? We look at studies involving these fonts to see evidence for or against them. The studies try to be scientific, but lack internal validity; i.e., the studies don’t eliminate the possibility that something else could explain the result. We provide a short summary of the studies and why they do not provide internal validity.