That being said, I found the study to be one of those trying to find the conclusion they want. The students were asked to explain details of the book as they read it for the first time and translate as they go. I can totally see myself failing this test and I used to read a lot. The way they conducted the study is just not the way I read.
It came across as the students were blamed for thinking out loud after they were asked to explain details as they go. I would be unfamiliar with terms like "whiskers" too. I would not know "Michaelmas term" meaning either.
And frankly, the whole paragraph is an atmospheric paragraph that carry no literal importance. You are supposed to take the feelings out of it, the exact composition of the mud layers is not the plot point nor of the books philosophy.