Altered states of consciousness

Conscious states that can be recognized by an individual or by an external observer of that individual as representing a major difference in behaviour and experience from ordinary baseline states of waking consciousness. They can be stable over time, and involve changes in a number of the subsystems of consciousness (Krippner, 1999). There have been a few attempts at building up taxonomies of altered states of consciousness (Tart, 1969, 1975, 1980; Gowan, 1975, 1980; Vaitl at al., 2005).