Usually when someone's talking, after a second of silence their new talking about something catches someone's attention, if the persons attention was waning to begin with, they'll prolly stop paying attention around the middle of the sentence.
It's like when you tell someone a list of things that need to be done usually people get the first half instead of the last. And then if they do get a part of the last half it's like this:
"So I need to do the laundry, and the dishes, and clean the bathroom" "and?" "something about the birds" "what about the birds?" "I don't know, I'll figure it out" "You need to clean their cage and give them new food and water, there was something else after that" "There needs to be a new trashbag in the trashcan" "which needs to be done AFTER you take the garbage out" "OH YEAH.