A friend, who I suspect has ADHD, once did this to me when I was explaining some complex stuff to her. I could not possibly imagine that someone got that explanation, if they fell off the thought train halfway through. So, I asked her about it and she told me that this is how she always processes sentences. She just buffers the words in RAM until the sentence is done. Then she slurps the words up and figures out the meaning.

I’m guessing, her brain is just really fast, but then runs off and does other thoughts while she’s supposed to listen, so she trained all her life to cope via buffering instead.