It has happened to me a few times that I have noticed: I am in control, interacting with someone. Suddenly I get this sensation that I am a particular someone else (i.e., a young boy). I see the body language and hear the words of the outside person in slow motion and my own senses seem heightened somehow. It feels as though the words of the outside person are going through me and beaming to another part of me, giving that other part a strong sense of connection with the person and the outer world. I feel that part of me "knowing" that the outside person is knowingly recognizing and addressing them. I feel like an empty vessel, a passageway, and then the alter having/causing this experience either comes out suddenly or comes very close to coming out.
It has happened three times lately, with two different alters, once with a stranger, and once with my husband (who denied calling the alter, though after she arrived and I then forced my way forward, he requested she return), and once with a friend/ex-boyfriend who is aware of the specific alter. (I didn't ask him if he was doing anything on purpose because I was struggling not to let the alter out, and I was afraid if I focused on her it would give her more ability to get out. In retrospect, I should have just let it happen rather than fight it. But I was trying to discuss something with my husband.)
When my husband denied having called the specific alter out, I could feel her heartbrokenness that he didn't "love" her enough to see her. Later I told my husband this, and he then did a gesture of affection towards me that she would like, causing her to come out. I complained, saying he was trying to summon her, her said he was just trying to hug me. Then he went on doing the same thing, bringing her out, until I got upset and pushed her back in. (I know I should just let it go. But it is so embarrassing and I feel so out of control. which is kind of silly because she has always been a part of the relationship.)
Have others experienced this? It's almost like they are experiencing "talking through" even if it isn't actually happening. Although maybe the example with my ex-boyfriend is partly due to talking through. Both the alters that I experienced this with are relatively young.