The study probably controlled for this, but not mentioned in the article: um's give listeners time to think. Corollary: removing disfluencies from online lectu

The study probably controlled for this, but not mentioned in the article: um's give listeners time to think. Corollary: removing disfluencies from online lectures diminishes comprehension. I took Ullman's "Automata" course, and they'd edited out all the um's and pauses etc in the vidoes, making them half as long. It reduces download size, but made them really difficult to understand. You don't have time to process one interesting thought before the next is upon you. Very different from live lectures. I often had to rewind 5 to 10 times. Yes, the material isn't easy and Ullman is full of insights, but this happened even with the beginning of the introductory lecture. From this article, it seems that the um's and pauses would also have helped signal difficult vs easy ideas. (Sometimes I worked hard to grasp his precise meaning, only to realize he was speaking casually).