"Trance mediumship" is often seen as a form of mental mediumship. Most trance mediums remain conscious during a communication period, wherein a spirit uses the medium's mind to communicate. The spirit or spirits using the medium's mind influences the mind with the thoughts being conveyed. The medium allows the ego to step aside for the message to be delivered. At the same time, one has awareness of the thoughts coming through and may even influence the message with one's own bias. Such a trance is not to be confused with sleepwalking, as the patterns are entirely different. Castillo (1995) states,
^ "Glossary of Key Words Frequently Used in Parapsychology" Archived 2010-12-24 at the Wayback Machine, Parapsychological Association website. "Materialization: A phenomenon of physical mediumship in which living entities or inanimate objects are caused to take form, sometimes from ectoplasm." Retrieved January 24, 2006 "Medium – Definition". Dictionary.com. Retrieved 23 March 2007.