Researcher Jeffery Martin has created the Center for the Study of Non-Symbolic Consciousness, kind of a clearing house for related research and a portal for people experiencing non-symbolic consciousness (aka enlightenment) who are interested in participating in research.
Martin's dissertation (which I've linked to before), is "Ego Development Stage does not predict Persistent Non-Symbolic Experience." Which to me means that psychological development is not particularly correlated with enlightenment.
From the site I came across a number of links. An interview with Non-Duality Magazine left me impressed with Martin's balanced academic style, and rather unimpressed with the often dogmatic notions of the interviewer.
He has a book out, The God Formula, which seems to cover some of the same ground. There are a series of videos supporting the book that cover info about non-symbolic consciousness.
In those videos I came across some other interesting sites, including the book "Stripping the Gurus: Sex, Violence, Abuse and Enlightenment" as well as references to Peter Fenner, a non-dual teacher and Alan Combs (book: Radiance of Being), a non-dual researcher. And if you've never come across it, The Sedona Method, a so-called releasing method, isn't bad but I would consider it a bit expensive.