I was able to show that people who stutter “stutter” when they read silently, as well as reading aloud! Although pressure/stress also makes stuttering worse, as you said.
That anticipation you mentioned - it’s called your phonological loop. It’s a cognitive process that happens subconsciously when we form words in our heads before speaking or as we’re reading. One school of thought about the cause of stuttering (and what my research supported) was that people who stutter are over vigilant in their phonological loop. Everyone analyses their speech before it’s articulated to a certain extent, but people who stutter seem to over analyse it like they’re almost expecting an error due to their stutter. That over analysis increases cognitive load and makes you even more likely to stutter; a self fulfilling prophecy, as you said.
I’ll take a look at my literature review later if I get a chance - I’ll let you know if I can find a paper about the effect of fonts.