Changes from one alter to another is called ‘switching’. For me, switching can happen really quickly; if something upsetting happens, I may start switching very rapidly. There may be several parts present and they might come out for a few seconds at a time, so quickly it might be missed (usually when this is happening I might just appear to be in a state of anxiety/unrest). There may be more than one alter present at one time.
Switching might happen less rapidly where one part comes out for a while e.g. an angry part might come out for the day, or if I have a big work event to do, the function part will take over. Another example might be if I were to sit down with paints and paper; this could easily provoke a switch to a child part seeing as it’s something children tend to enjoy doing.
Switching can also happen for me in longer phases, as in I will notice usually a more dominant part for a few weeks. So for several weeks I might have absolutely no emotions about anything; life feels really easy; I go to work, do everything I should, come home, watch TV etc etc but not really be engaged in life. This is function mode. I call it that because to me it is a non person, as it doesn’t have emotion, but I feel a bit guilty that I’ve learnt to think of it that way as for me this is the easiest alter to live as and probably the most useful.
In function mode nothing is bad and nothing is great. NB I have to activelytry to switch myself out of this mode in order to go to my therapy sessions otherwise I would sit in silence and not be able to relate to any questions about ‘feelings’ or ‘parts’. I have spent years of my life at a time in this mode and that is probably part of the reason I am missing a lot of memories; it’s almost like a robot version of me was present for those years of my life.
Another part might then take over for several weeks at a time such as an angry part (life is VERY difficult in this case) or a depressed part (very difficult to work as this part) etc.
It is usual for other alters to make appearances no matter which part is being dominant in any phase. E.g I may be in function mode but a child alter might still come out for an hour or so.
Stressful situations can cause me to switch but I might switch as well if a situation is more suited to one alter e.g. watching fireworks at Halloween caused me to switch to a child alter, who then got very upset when the loud ones went off so an older, motherly alter also ‘came out’ to comfort the child alter resulting in two alters being present at the one time (plus me as an observer). Complicated!
I don’t know what triggers the more long term switches to take place. I could be happily in function mode for weeks and then wake up one morning suddenly ‘feeling’ and I’ll realise something is different.
I'm still learning about all of this myself, but if you have any questions or comments, I would be happy to hear them.