David_Jay,
About séances:
So based on what I have read, a séance is a meeting at which people attempt to make contact with the dead, especially through the agency of a medium.
The medium and/or others enter into a trance, an altered state of consciousness, using methods such as:
- meditation
- self-hypnosis
to induce an altered state of consciousness similar to persons having a mystical experience.
The seance is characterized by trances, the medium channelling information from the "spirits of the dead" whom he/she has contacted who speak through him/her, or through automatic writing in a native or different language, slate writing, artwork, glossolalia (speaking in tongues) etc - all of which are a means of communicating with "spirits".
There may also be physical changes in the appearances of the medium and/or other participants while they are in the trance/altered state of consciousness state.
Researchers/neuroscientists, have examined brain activity during trances/altered state of consciousness (ASC) experiences.
When a person enters an ASC part of their brain is shut down and another part of the brain takes over:
"Channeling Spirits Shuts Down Parts Of Brain"
http://news.discovery.com/human/psychology/spirituality-brain-function-mediums-121116.htm:
See also:
http://www.andrewnewberg.com
This neuroscientist has also researched and written much about the neurological basis for altered state of consciousness experiences, religious and spiritual experiences and indicates that these experiences are dramatically influenced by changes in brain activity.