Ok, I can see where you're going with that thought. The alters do often percieve physical differences that are not there. Some physical differences do exist, though, actually. The data show that different alters often have different eye prescriptions, for one example. I don't see why the various alters couldn't exist without the others, though. They aren't even aware of eachother's existance at the beginning of therapy the majority of the time. In the beginning, only maybe one alter is aware of the others. It takes work to gain co-consciousness. And the alters, to the best of their knowledge, are complete and separate individuals. In fact, that is required for the diagnosis to be made. A personality is a fairly stable pattern of relating to the world and the self. Each alter has their own personality.

-comfort the disturbed and disturb the comfortable-