 Nelson interpreted several major psychiatric disorders as altered states of consciousness, involving expansion of the self-concept, and, in some instances, contact with a spiritual dimension.Other clinicians that have engaged with transpersonal approaches include Bruce Scotton, Bruce Victor, David Lukoff, Francis Lu and John Hiatt, who all contributed to Psychiatric Annals, Volume 29.Bruce Scotton presented what he called the "assumption of transpersonal psychiatry"; which is the idea that human development extends to levels beyond the ego, and that this development is recognizable across cultures.