What causes new alters?

I wasn't open to the idea of finding parts or alters. The DID specialist was pointing out 4 to me and I could see how he was reasoning that way. But I refused to do anything to reinforce these parts or to give them individuality. No journaling to get in touch with parts. Made up my mind that I was not going to get in touch with any parts outside of therapy session. Was not going to try to uncover memories.

Found out I didn't have to do any of these things to get better.

Puppieskittens, I'm glad that you and your T approached your situation in way that worked for you, I am. However, I think it's necessary to point out to others here that the Guidelines for Treating Dissociative Identity Disorder in Adults by the International Society for the Study of Trauma and Dissociation (ISSTD) make very different recommendations for DID therapy, particularly in the area of addressing memories and including alters in the process.

A new alter can form without much rhyme or reason.

My system was stable for decades until one day at work a man walked up to me and shook my hand. Poof! I had a new alter, who took almost a year to work her way to the surface. Meanwhile I had flashbacks, heard a voice saying the same things over and over again, was flooded with affect, etc. I think the man has DID and was projecting intensely some need of his own for interpersonal contact.

There is a concept in some schools of psychoanalysis called projective identification: in short, one person can insert an identity state into another person. Neither person is conscious of this happening.

Una+ wrote:A new alter can form without much rhyme or reason.

My system was stable for decades until one day at work a man walked up to me and shook my hand. Poof! I had a new alter, who took almost a year to work her way to the surface. Meanwhile I had flashbacks, heard a voice saying the same things over and over again, was flooded with affect, etc. I think the man has DID and was projecting intensely some need of his own for interpersonal contact.

There is a concept in some schools of psychoanalysis called projective identification: in short, one person can insert an identity state into another person. Neither person is conscious of this happening.

So it's very much a "the mind learns to do this, so it's second nature/easy to do again" kind of thing? Wow…