SOME PARANORMAL PHENOMENA involve an altered state of consciousness, a condition where the mind is awake yet not in its normal state. Channeling, for example, begins with the channeler going into a trance, which is a waking mental condition that appears much like sleep.

Scientists disagree about whether or not altered states can exist without the use of drugs or the presence of mental illness. This disagreement applies even to hypnosis, which was once widely accepted as an altered state. Hypnosis is a seemingly trancelike condition that apparently enhances a person's memory, diminishes the sensation of pain, and leaves the mind open to suggestions made by the hypnotist. However, many scientists now consider it the result of normal brain functions. Reporter Roger Highfield discusses both sides of the issue:

Most scientists now reject the traditional view...