I have from time to time turned e into another creature or object for a few minutes. We have a lot more exploring to do here, because it's not all that easy to discuss what these episodes feel like. She comes back giggling quietly, saying nothing until I prompt her. I almost have to interview her, with yes/no questions, before she can describe it. My sense is that this reflects the depth to which she 'becomes' the object, so instead of monitoring the experience while it's occurring she has to recall the details later.
So, as a couple of commenters have suggested, I briefly turned her yesterday into first, a dragon, and then a Barbie.
"You are convinced that you are a dragon" was all I said. Afterwards: Where were you? "In a cave." Did you have wings? "Yes." Did you have scales? "Yes." Did you have claws? "Yes." Did you breathe fire? "No." Was anyone else there? "No."
So then I said she was a dragon and she was flying. Afterward: Was it day or night? "Day". Where were you? "Scotland, I think... it looked like pictures of Scotland. There were perfect little sheep on the hillside."
OK, so she wasn't bowled over by the experience, and we both think it's because she has very little experience with dragons. She's not read much about, role-played, or thought about dragons. She said she felt like a "cartoon" dragon. Hey, at least she wasn't purple.
For comparison, I said: "You're convinced you're a Barbie doll, being played with by a little girl." Same quiet giggling afterward. How did you feel? "Very blonde." How were you dressed? "I wasn't; I just had on a pink top; she was taking that off." She was struck by how object-like and inanimate and manipulated she felt.
Overall, it felt much more vivid to her, and the obvious reason is that she spent some time as a girl actually playing with Barbies. I think the extent to which she has experiences or images or desires to draw upon determine how compelling the scene feels.
So there you go. We'll explore this some more and let you know what we discover.
(Last night I turned her into a Real Doll for a while. That's a story for another time.)