Well David, if you wish to be closed-minded about it, that is your choice. But I have observed otherwise. If you wish, try this experiment. Spend an hour or two on your back with your head hanging back so that the world is viewed upside down..perhaps watch TV as Steve suggests. In an hour, observe how the world seems to be orientated. Then close your eyes, sit up and see if the world looks oriented "normally" immediately after opening your eyes.
This is actually how I experienced this the first time...before I ever used a view camera. I was floating on my back on a Texas lake back in the early 70's. Of course, the above experiment might fail...your mind might be too inflexible.