Is Everything I See Really Inside My Head?

One might think the answer to this question too patently obvious to require the expensive attentions of a professional philosopher. After all, while I write I can see my wife—and it is hardly likely that she is inside my head. And what is more, I see her head and she sees mine—but if the principle suggested in my initial question were both true and general then her head would have to be inside my head and my head would have to be inside her head. And this is not just unlikely—it is logically impossible.