If the person you’re speaking with pauses, trying to think of a word or concept, don’t jump in to finish their thought.
Not always the easiest guideline to follow, is it? We can typically listen to and absorb the spoken word at about four times the rate the other person is speaking. Plus, as you know, some people… speak… even… more… slowly… than… that. (!)
But please understand that having someone else jump in to finish your thought is one of the most annoying social behaviors. If you want to be known as a great conversationalist, you’ll never — ever — do this.
When you’re in a conversation and the other person pauses to think of a word or phrase, let them finish. No matter how long it takes. Let them finish. Really, let them finish.
The only exception is if the other person actually asks you for help remembering whatever they can’t. Until then, wait. When you cut in, you send a signal that you’re losing patience, and you make the other person uneasy for the rest of the discussion — afraid of annoying you again by talking too slowly or pausing for too long.
By contrast, when you’re patient and allow the other person as long as they need to make their point, they’ll come away from your talk having enjoyed it much more — and thinking of you as a great conversationalist.
Related tip: If the pause is really long and nothing else works, bite the inside of your lip.