I wonder if this relates to how comfortable people are with silence? Sometimes one or the other person can feel anxious in the presence of silence because it does not fit the profile of "work being done".
People often dismiss pure thought as effort. But when you think about it that is all programming really is. I worked with a person that started his programming career using cards. Even though his current job provided him a nice editor and build system he would write his program and simply execute in his head for the longest time before even attempting to compile it. He would then make a couple of changes and he was done.
