Some states of consciousness don’t occur naturally and must be induced in some way. These include hypnotic states, meditative states, and drug-induced states.


Hypnosis is a procedure that opens people to the power of suggestion. A hypnotist puts a subject in an altered state by encouraging relaxation and sleepiness and often describing the sorts of physical sensations a subject should be feeling. Once a subject is in the altered state, he or she may act, perceive, think, or feel according to the hypnotist’s suggestions. Not everyone can be hypnotized, and some people are more hypnotizable than others. The following chart shows what hypnosis can and can’t do.

Hypnosis can:Hypnosis can’t:
Cause people to be relaxed, have a narrowed focus of attention, and be highly engaged in fantasiesWork equally effectively for everyone
Produce anesthesia and treat a range of psychological and medical problemsForce people to do things against their will
Cause hallucinations and distortions in sensory perceptionMake people act in ways that would normally be beyond their physical or mental abilities
Reduce inhibitionsReliably increase the accuracy of memories
Cause changes in behavior after the hypnosis has endedAllow people to actually reexperience past events or lives

If hypnotized people are instructed to forget what happened during hypnosis, they later claim to have no memory of it. This phenomenon is called posthypnotic amnesia.

A hypnotic state isn’t sleep—brain waves, for example, do not reliably change during hypnosis as they do during sleep. Researchers don’t even agree that hypnosis is an altered state of consciousness. Researchers propose two main theories about hypnosis:

  • Ernest Hilgard proposed that hypnosis causes people to dissociate or divide their consciousness into two parts. One part responds to the outside world, and the other part observes but doesn’t participate. According to this theory, hypnosis can make people not react to pain because hypnosis separates the part of consciousness that registers pain from the part of consciousness that communicates with the outside world.
  • Many other researchers, such as Theodore Barber and Nicholas Spanos, think hypnosis happens when a suggestible person plays the role of a hypnotized person. According to this theory, hypnotized people simply behave as they think they are expected to.


Meditation is the practice of focusing attention. People meditate to enhance awareness and gain more control of physical and mental processes. Techniques used in meditation vary and include activities such as repetitive chanting and breathing exercises.

Meditative states are associated with an increase in alpha and theta brain waves, and physical indicators of relaxation such as slowed pulse and breathing. Some researchers have found that meditation has long-term effects such as improving physical and mental health and reducing stress. However, researchers disagree about whether meditative states are unique states of consciousness. Some researchers believe relaxation techniques can produce the same kind of state produced by meditation.

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