Near Death Experiences

Psy391D - Class 25

(This page last updated 27 November, 2004.)

Optional Reading

Greyson, B. (1998). Biological aspects of near death experiences. Perspectives in Biology and Medicine, 42, 14-32.

van Lommel, P., van Wees, R., Meyers, V., & Elfferich, I. (2001). Near-death experience in survivors of cardiac arrest: a prospective study in the Netherlands. The Lancet, 358, 2039-2045.

Parnia, S., & Fenwick, P. (2002). Near death experiences in cardiac arrest: visions of a dying brain or visions of a new science of consciousness. Resuscitation, 52, 5-11.

Blanke, O., Ortigue, S., Landis, T., & Seeck, M. (2002). Stimulating illusory own-body perceptions. Nature, 419, 269-270.

Owens, J.E., Cook, E.W., & Stevenson, L. (1990). Features of the near death experience in relation to whether or not patients were near death. The Lancet, 336, 1175-1177.

Kellehear, A. (1993). Culture, biology, and the near-death experience. A reappraisal. The Journal of Nervous and Mental Disease, 181, 148-156.

 Questions to Answer while Reading

  1. What are the most unusual events that are reported regularly in near-death experiences?
  2. How can these events be studied scientifically?
  3. What are the different possible explanations for these events?

 

What is a Near-Death Experience (NDE)?

Conditions under which NDE's occur.

  • Lack of oxygen to the brain
    • Lack of blood flow
    • Breathing stopped

Different experiences reported.

  • Hearing that they are dead
  • Feelings of peace and quiet
  • Noise
  • Moving through a dark tunnel
  • Out of body experience (OBE)
    • See own body from above.
    • Sometimes see other rooms in same building.
  • Meeting others, usually dead relatives
    • Children sometimes see living friends or a pet that has died.
  • Seeing a light or a being of light
  • Life review
    • Sometimes forward, sometimes backwards, sometimes unordered.
  • Approaching a border or point of no return
  • Returning to the physical world

NDE's are generally pleasant, although some people report very unpleasant experiences.

  • hellish environment
  • no envirnoment at all; just boring void

For many people, a near-death experience can change their outlook on life.

  • less fear of death
  • report more involvement with family
  • more interest in spirituality
  • may value material possessions less
  • high rate of divorce, apparently because of changed priorities

Similarities and Differences across NDE's

Most people only report a subset of the experiences listed above.

Differences between individuals.

Systematic studies show that most people suffering cardiac arrest do not report a NDE.
What determines who does and who does not?

Differences do not seem to be related to medical condition, or to level of fear before NDE occurred.

May be more likely in younger people.

Perhaps they are more likely to survive the traumatic events that trigger NDE.

Why are there such big differences in the environments they report and the people (and other beings) they meet?

Jung's experience
  • floating above Ceylon
  • Hindu Temple

Differences across cultures.

Reports of OBE's, tunnels, and lights less prevalent in some cultures than in others.
May depend on the prevalent religion.

Japanese study shows people there have somewhat gloomier images.

Comparison of American and Hindu NDE's

  • Americans often see their own bodies, while Hindus don't.
  • Differences in explaining why they came so close to death and then returned.
    • Hindus often report the the being transporting them discovers a mistake was made.
    • Americans more likely to report that dead relatives told them to return, or that they felt a duty to living persons.

 

Producing NDE's Without being Near Death

Impending accident
life review

Drugs

opiates

LSD and other hallucinogens

ketamine (Jansen)

Sensory Deprivation

Brain Stimulation

Stimulation of right angular gyrus produces OBE (along with other illusions) in one patient (Blanke et al).

 

Possible Scientific Accounts

Sensory Deprivation
Mind imposes an interpretation on sensory experience, and can continue doing this even when there is no sensory input.

Inhibitory neurons may succomb to lack of oxygen before excitatory neurons

For a period, anoxia may produce more brain activity rather than less.

Random activity in visual cortex could produce a visual experience that seems like moving through a tunnel.

Endogenous Opiates

Producing feelings of joy and calm.

 

Are Patients Aware of Physical-World Events during OBE's?

Patient Reports
The Case of the Missing Dentures

Possible Explanations

Problems with single anecdotes
How many clearly false reports are ignored?

Perhaps it is all imagined as brain is shutting down or starting back up.

Important to determine veracity of events reported during OBE's.

Maintain hearing and some cognitive ability for a time without blood flow.

Can be aware of events because of what they hear.

Can construct images to correspond to what they hear.

With no visual input, may be hard to discriminate between seeing and imagining.

Without being constrained by visual input, viewpoint of imagined scene could shift.

Brain Activity

 Based on EEG measurements and animal studies, Parnia argues that neural activity should stop soon after heart stops.

Patients report extreme clarity of thought at a time when it should be the most difficult.

 

Questions to be Investigated

Are there personal and social factors that can explain the differences in reported experiences across individuals?

Are there verifiable instances of physical-world events reported during out-of-body experiences?

To what degree can brain activity continue after blood flow stops?

Can the experiences reported during near-death experiences be produced by physiological events within the brain?

 

 

Relevant Web Sites

 

Psych 391D: Consciousness Kyle Cave Psychology Dept. U. Mass.