There should really be full discussion post about this, since it keeps getting brought up.

EDIT: So I made one. If there isn't interest, well, at least it's spurred me to consolidate a bibliography

In addition to what I wrote in the other thread:

Luhrmann wrote a book, When God Talks Back, about her experiences with evangelicals, which might be useful. She also succeeded in inducing tulpa-like visions of Leland Stanford, jr. in experimental subjects.

The tulpa community also seems to have a fondness for amateur psychological research, although I imagine there'll be a lot of chaff and unfinished projects in there.