Let them know your preference of how you want to indicate "not finished" pauses. For some people, it's just "um." For John Hendrickson, and I don't know if it's his conscious decision or not, his "not finished" pauses are his stuck-in-air like hand gestures plus throat sounds. For Amanda Mammana, it's "uh" and then her hand gesture which does look like a "wait for me, I'm getting there" gesture to anyone. Other options are 1. tapping your own shoulder 2. making a "i'm thinking" facial expression on purpose I sometimes frown in the middle of blocks. I tell people that I have three "not finished" signals: frowning, shoulder tap, and "um".