Suppose you are given this sentence (‘A gave a ball to B’) and you, in general, start thinking about it – this event. You might think – how did he give the ball? (That is, placed it in his hand or threw it to him to catch from a short distance or………etc.)
Another thought could be (about B this time) – And what did B do? Did he take it? What was B’s feeling/reaction?
Now you thought about A – how did he give the ball? (and/or some other things). But you had something to think from – A gave a ball. So a follow-up to this is – how did he give? Why did he give? etc. But B is just a silent inactive agent in this event. There is nothing talked about B / B doing. It is not even stated “B took a ball from A”. Still you came up with a question about B (how did B react? etc.) Where is the inertia for that? Where is the pointer to that?
The only inertia/momentum for this is – ‘talked about A, so talk about B’ ……. ‘A gave a ball (A did so and so), so what did B do?’ ……. ‘Something about A; so something about B’…………in this tune. Notice the ‘And’ before the very first question about B.
This can be merely called “Linguistic Inertia” – where the sheer and mere presence and arrangement of certain words brings certain things to your mind upon coming across a piece of data, in a certain pattern/tune/rhythm….etc., so to speak. They dont require “real” thinking.