A touch screen on the other hand that don't register where you click but just randomly chose coordinates now that would be noticed.
When I went to her house I got on her computer and said, "where's the mouse?" She didn't know what I was talking about, of course. She sewed a lot, so when I discovered that she thought it was some kind of foot pedal, I guess that makes sense.
These things are always illuminating. "Scroll up" gets a confused expression. She initially just tried moving the mouse. Click the scrollbar. What's that? How do you click? The button on the mouse? Which one? Do I click and release or hold the click? etc...
It's amazing how many minor details we can't help but take for granted.