In my case, I never would know if it weren't for my family. My experience with DID, since I was young has been a mystery to me. I can't remember a fraction of a second when I'm in and someone else is out. I have no memory of the event and am left only with the feeling sometimes that time is missing. Sometimes I don't realize it at all. If it had not been for my family telling me the things I would say or do durring these memory losses, I would have had no clue. Until you start the co conscious phase, I don't think you can personally know that there are others. There are voices however that I hear on occassion. It's about as often as I lose time I hear voices. You can tell that they are not from outside of your head but they are so loud it can cause a headache. It's the most aggravating thing sometimes when I hear someone yell, it hurts my ears and people see me squeezing my eyes shut and my head starts hurting but no one can see or hear why, but me. It's frustrating but what isn't nowadays.