No it's not a joke, claiming that being harder to read help understanding things remind me the ancient Victorian era, the Cilicium idea, the "all work and no play" song etc. I do not consider it a scientific truth but only another reactionary claim that can be as scientific as Franklin idea of forcibly wake up people with a cannon shoot in any road.
You may not know it, but there are studies backing this up. Whether you consider it a scientific truth or not is barely relevant. What is interesting to know is that not all disfluencies are created equal: blurring text and adding visual noise don't help, apparently because they don't engage the right part of the visual pathway.
Thanks for the link, yes I do not know these kind of studies before, and I skim read it just now, however I also see claim of non reproducibility and different results from other studies in this page.
Personally I notice that force me to read difficult fonts does not help at all my understatement or my memory. In the end my idea, without statistical proof of course, is that such contrasting observation are simply noise. Perhaps due to a sample size not big enough, perhaps due to tested individual itself but still noise.
Also IMVHO such studies exist for a reason: teacher's mean quality is getting lower and lower due to various schools reforms and since admit errors it's not a thing these days someone try a sort of "montecarlo test" in the desperate search of a solution to stop the bleeding. Other find such tentative nice for their business because new stuff means new sales for someone.
