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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Near-death experience | 6/8 | https://en.wikipedia.org/wiki/Near-death_experience | reference | science, encyclopedia | 2026-05-05T04:18:06.795176+00:00 | kb-cron |
==== Expectancy model ==== Another psychological theory is called the expectancy model. It has been suggested that although these experiences could appear very real, they had actually been constructed in the mind, either consciously or subconsciously, in response to the stress of an encounter with death (or perceived encounter with death), and did not correspond to a real event. In a way, they are similar to wish-fulfillment: because someone thought they were about to die, they experienced certain things in accordance with what they expected or wanted to occur. Imagining a heavenly place was, in effect, a way for them to soothe themselves through the stress of knowing that they were close to death. Subjects use their own personal and cultural expectations to imagine a scenario that would protect them against an imminent threat to their lives. Subjects' accounts often differed from their own "religious and personal expectations regarding death", which contradicts the hypothesis they may have imagined a scenario based on their cultural and personal background. Although the term NDE was first coined in 1975 and the experience first described then, recent descriptions of NDEs do not differ from those reported earlier than 1975. The only exception is the more frequent description of a tunnel. Hence, the fact that information about these experiences could be more easily obtained after 1975 had not influenced people's reports of the experiences. Another flaw of this model can be found in children's accounts of NDEs. These are similar to adults', despite children being less strongly affected by religious and cultural influences about death.
==== Dissociation model ==== The dissociation model proposes that NDE is a form of withdrawal to protect an individual from a stressful event. Under extreme circumstances, some people may detach from certain unwanted feelings in order to avoid experiencing the emotional impact and suffering associated with them. The person also detaches from one's immediate surroundings.
==== Birth model ==== The birth model suggests that near-death experiences could be a form of reliving the trauma of birth. Since a baby travels from the darkness of the womb to light and is greeted by the love and warmth of the nursing and medical staff, and so, it was proposed, the dying brain could be recreating the passage through a tunnel to light, warmth and affection. Reports of leaving the body through a tunnel are equally frequent among subjects who were born by cesarean section and natural birth. Newborns do not possess "the visual acuity, spatial stability of their visual images, mental alertness, and cortical coding capacity to register memories of the birth experience".
=== Physiological models === A wide range of physiological theories of the NDE have been put forward, including those based upon cerebral hypoxia, anoxia, and hypercapnia; endorphins and other neurotransmitters; and abnormal activity in the temporal lobes. Neurobiological factors in the experience have been investigated by researchers in the field of medical science and psychiatry. Among the researchers and commentators who tend to emphasize a naturalistic and neurological base for the experience is the British psychologist Susan Blackmore (1993), with her "dying brain hypothesis".
==== Neuroanatomical models ==== According to Greyson, multiple neuroanatomical models have been proposed, wherein NDEs have been hypothesized to originate from different anatomical areas of the brain, namely: the limbic system, the hippocampus, the left temporal lobe, Reissner's fiber in the central canal of the spinal cord, the prefrontal cortex, and the right temporal lobe. Neuroscientists Olaf Blanke and Sebastian Dieguez (2009), from the Ecole Polytechnique Fédérale de Lausanne, Switzerland, propose a brain-based model with two types of NDEs:
"type 1 NDEs are due to bilateral frontal and occipital, but predominantly right hemispheric brain damage affecting the right temporal-parietal junction and characterized by out-of-body-experiences, altered sense of time, sensations of flying, lightness vection and flying" "type 2 NDEs are also due to bilateral frontal and occipital, but predominantly left hemispheric brain damage affecting the left temporal parietal junction and characterized by feeling of a presence, meeting and communication with spirits, seeing of glowing bodies, as well as voices, sounds, and music without vection"
They suggest that damage to the bilateral occipital cortex may lead to visual features of NDEs such as seeing a tunnel or lights, and "damage to unilateral or bilateral temporal lobe structures such as the hippocampus and amygdala" may lead to emotional experiences, memory flashbacks or a life review. They concluded that future neuroscientific studies are likely to reveal the neuroanatomical basis of the NDE, which will lead to the demystification of the subject without needing paranormal explanations. French has written that the "temporal lobe is almost certain to be involved in NDEs, given that both damage to and direct cortical stimulation of this area are known to produce a number of experiences corresponding to those of the NDE, including OBEs, hallucinations, and memory flashbacks". Vanhaudenhuyse et al. (2009) reported that recent studies employing deep brain stimulation and neuroimaging have demonstrated that out-of-body experiences can result from a deficient multisensory integration at the temporal-parietal junction and that ongoing studies aim to further identify the functional neuroanatomy of near-death experiences by means of standardized EEG recordings.
==== Criticism ==== Blanke et al. admit that their model remains speculative due to the lack of data. In addition, the reports of those who had the brain stimulation were almost nothing like OBEs reported by those who had NDEs, mainly characterized by a sense of elevation and (often limited) spatial awareness, while other characteristics of NDEs were absent. Anomalies such as seeing maps, half-bodies and duplications were also noted. Likewise, Greyson writes that although some, or any of the proposed neuroanatomical models may serve to explain NDEs and pathways through which they are expressed, they remain speculative at this stage, since they have not been tested in empirical studies.