Appendix C

Glossary of Key Terms

This glossary defines the major medical, scientific, philosophical, and theological terms used throughout this book. Terms are arranged alphabetically. Where a term is used primarily by a specific author (such as Marsh’s “ECE”), this is noted. Plain-English explanations are provided alongside technical definitions, consistent with the book’s commitment to making complex ideas accessible to all readers.

Medical and Scientific Terms

Autoscopic Experience

An experience in which a person sees their own body from an external viewpoint. Think of it as watching yourself from across the room. This can happen during an NDE when the person perceives their body lying on the operating table or hospital bed from a vantage point above or beside it. Not all autoscopic experiences are NDEs—some occur in neurological conditions—but the autoscopic component is one of the most common and evidentially important features of near-death experiences because it is the element most frequently associated with veridical (verified) perceptions.¹

Brain Death

The complete and irreversible loss of all brain function, including the brainstem. Brain death is the legal standard of death in most countries. It is distinct from cardiac arrest (in which the heart stops but the brain may retain some residual function for a short time) and from a persistent vegetative state (in which the brainstem continues to function). When a person is declared brain dead, there is no measurable electrical activity anywhere in the brain, no brainstem reflexes, and no capacity for spontaneous breathing. This is the most extreme end of the spectrum—and some NDE cases (such as Eben Alexander’s prolonged coma with documented cortical inactivity) approach this level of impairment.²

Cardiac Arrest

The sudden cessation of effective heart function. When the heart stops pumping blood, the brain is deprived of oxygen and glucose, and consciousness is typically lost within six to twenty seconds. An electroencephalogram (EEG) typically goes flat within ten to thirty seconds of cardiac arrest. This is significant for NDE research because many veridical NDE reports occur during confirmed cardiac arrest—a time when, according to mainstream neuroscience, the brain should be incapable of generating complex conscious experience. The majority of medically documented NDEs with veridical elements occur in the context of cardiac arrest, making it the single most important medical setting for NDE evidence.³

Clinical Death

The cessation of heartbeat and breathing. Clinical death is not the same as brain death or biological death (the irreversible decay of cells). A person in clinical death can sometimes be resuscitated if medical intervention occurs quickly enough. Most NDE cases involve patients who were in clinical death and were subsequently revived. The distinction matters because critics sometimes argue that “clinically dead” does not mean the brain was completely nonfunctional—a point addressed at length in this book.

Confabulation

The unconscious production of fabricated or distorted memories without the intent to deceive. In plain terms, confabulation is when your brain “fills in the blanks” in memory with details that feel real but never actually happened. Skeptics sometimes argue that NDE reports are confabulations—that the brain, upon recovering from a crisis, constructs a narrative that seems real to the experiencer but is actually assembled from fragments of prior knowledge, expectation, and imagination. The veridical evidence challenges this explanation because confabulated memories would not be expected to match objective reality with the accuracy documented in the strongest NDE cases (92% accuracy in Holden’s 2009 analysis).⁴

ECE (Extra-Corporeal Experience)

A term coined by Michael N. Marsh in his book Out-of-Body and Near-Death Experiences to encompass both out-of-body experiences (OBEs) and near-death experiences (NDEs) under a single umbrella term. Marsh prefers “ECE” because he views both phenomena as variations of the same underlying brain-state process. This book uses the more widely recognized terms “NDE” and “OBE” because they are the standard terminology in the research literature and because adopting Marsh’s terminology would implicitly accept his interpretive framework.⁵

EEG (Electroencephalogram)

A medical test that measures the electrical activity of the brain using electrodes placed on the scalp. The EEG picks up the collective electrical signals of millions of neurons firing in the outer layers of the brain (the cortex). A “flat” EEG (also called an isoelectric EEG) means that no measurable electrical activity is being detected in the cerebral cortex. During cardiac arrest, the EEG typically flatlines within ten to thirty seconds. This is a crucial piece of evidence in NDE research: if a patient reports a rich, detailed, veridical NDE during a period when their EEG was flat, the physicalist must explain how a brain producing no measurable electrical activity generated a complex conscious experience. Critics sometimes argue that the EEG only measures surface cortical activity and that deeper brain structures might still be active—a point addressed in several chapters of this book.⁶

Endorphins

Natural chemicals produced by the brain that function as the body’s built-in painkillers. Endorphins are chemically similar to opioids like morphine. Some skeptics have proposed that a surge of endorphins during a medical crisis could produce the feelings of peace, euphoria, and painlessness commonly reported in NDEs. However, endorphin release typically produces a general sense of well-being, not the highly structured, detailed experiences reported in NDEs (tunnels, encounters with specific deceased persons, accurate veridical perceptions). Moreover, endorphins would not explain how patients accurately perceive real events in their environment. Marsh discusses this theory in chapter 9 of his book.⁷

Heautoscopy

A neurological experience in which a person sees a “double” of themselves at a distance, sometimes accompanied by confusion about which body is the “real” one. This is distinct from a typical NDE out-of-body experience in several important ways: in heautoscopy, the person usually remains aware of being in their own body while also seeing a copy of themselves; the “double” is often incomplete or distorted; and the experience does not include the rich, structured elements typical of NDEs (tunnel, light, deceased persons, life review, veridical perception). Marsh and other critics sometimes lump NDEs together with heautoscopy as though they were the same phenomenon, but the differences are significant.⁸

Hypercarbia (Hypercapnia)

An excess of carbon dioxide (CO₂) in the blood. When the body is not breathing effectively, CO₂ builds up. Some researchers have proposed that elevated CO₂ levels during cardiac arrest could trigger NDE-like experiences. A study by Klemenc-Ketis and colleagues (2010) found a correlation between higher CO₂ levels and NDE reports in cardiac arrest survivors. However, this correlation does not explain the veridical content of NDEs (accurately perceived events), and other studies have failed to replicate the finding. Marsh addresses this hypothesis in chapter 9.⁹

Hypnagogic / Hypnopompic

Hypnagogic experiences occur during the transition from wakefulness to sleep; hypnopompic experiences occur during the transition from sleep to wakefulness. Both can involve vivid hallucinations, sensations of floating, paralysis, and a sense of a “presence” in the room. Some skeptics (particularly Kevin Nelson) have argued that NDEs are a form of REM intrusion—essentially, the brain slipping into a dream-like state during a medical crisis—and that hypnagogic/hypnopompic phenomena explain the vivid imagery of NDEs. The problem with this explanation is that hypnagogic and hypnopompic hallucinations are not veridical—they do not correspond to objective reality—and they do not produce the structured, consistent elements found across NDE reports.¹⁰

Hypoxia (Cerebral Hypoxia / Anoxia)

A condition in which the brain does not receive enough oxygen. Anoxia is the complete absence of oxygen to the brain. Hypoxia is probably the single most commonly cited physiological explanation for NDEs. The argument goes like this: when the brain is starving for oxygen, it malfunctions, and that malfunction produces the strange experiences people report during NDEs. But there are serious problems with this explanation. First, hypoxia typically produces confused, fragmented, agitated experiences—not the clear, coherent, highly structured experiences reported in NDEs. Second, hypoxia affects everyone whose brain is deprived of oxygen, but only a minority of cardiac arrest survivors report NDEs—and prospective studies like van Lommel’s have found no correlation between the degree of hypoxia and whether an NDE occurs. Third, and most importantly, hypoxia cannot explain veridical perception. A malfunctioning brain might generate hallucinations, but those hallucinations would not be expected to accurately match events happening in the real world.¹¹

Hypothermic Cardiac Arrest (Standstill Operation)

A surgical procedure in which the patient’s body temperature is dramatically lowered, the heart is stopped, and the blood is drained from the brain in order to perform surgery on blood vessels in or near the brain. During this procedure, the brain has no blood flow, no electrical activity (flat EEG), and no brainstem reflexes. The patient is, by every measurable criterion, without brain function. The Pam Reynolds case is the most famous NDE to occur during hypothermic cardiac arrest. Reynolds reported detailed, verified perceptions of events during her surgery—at a time when her brain was demonstrably nonfunctional. This type of case poses the most extreme challenge to physicalist explanations of NDEs.¹²

Ketamine

A dissociative anesthetic drug that, at sub-anesthetic doses, can produce experiences with some similarities to NDEs, including out-of-body sensations, a feeling of floating, and vivid imagery. Karl Jansen proposed that the brain might release its own ketamine-like chemicals (acting on NMDA receptors) during a crisis, producing NDE-like experiences. However, ketamine experiences differ from NDEs in important ways: ketamine often produces frightening, bizarre, and disorienting experiences, while NDEs are typically described as hyper-real, peaceful, and coherent. Ketamine does not produce veridical perceptions. And no endogenous (naturally produced) ketamine-like substance has been identified in the dying brain at the concentrations that would be required to produce the proposed effects.¹³

NDE (Near-Death Experience)

A profound subjective experience reported by some individuals who come close to death or who are revived from clinical death. Common elements include: a feeling of peace and painlessness; a sense of leaving the body (out-of-body experience); moving through a dark tunnel; encountering a brilliant, warm light or a “being of light”; meeting deceased relatives or other beings; experiencing a life review (seeing one’s entire life in a panoramic vision); reaching a border or boundary beyond which one cannot pass; and being told or choosing to return to the body. Not all NDEs include all of these elements. The term was coined by Raymond Moody in his 1975 book Life After Life. Bruce Greyson developed a standardized NDE Scale to measure the depth and features of NDEs. NDEs have been reported across cultures, religions, ages, and historical periods.¹⁴

OBE (Out-of-Body Experience)

An experience in which a person’s center of awareness appears to be located outside their physical body. During an OBE, the experiencer typically perceives their own body from an external vantage point (usually from above) and may observe their surroundings with apparent clarity. OBEs can occur as part of an NDE, but they can also occur independently (during meditation, extreme stress, certain neurological conditions, or spontaneously). In the context of NDE research, OBEs are evidentially important because they are the component most likely to produce veridical perceptions that can be checked against reality. Marsh rightly notes that OBEs and NDEs are related but distinct phenomena.¹⁵

REM Intrusion

A phenomenon in which features of REM (Rapid Eye Movement) sleep—the stage of sleep in which vivid dreaming occurs—intrude into waking consciousness or into other stages of brain activity. Kevin Nelson proposed that NDEs are caused by REM intrusion: the crisis-stricken brain, he argued, slips into a dream-like state that the person later interprets as a real experience. Problems with this hypothesis: (1) REM intrusion produces hallucinations that do not correspond to reality, while NDEs frequently include veridical elements; (2) the brain regions needed for REM activity require at least some blood flow and electrical activity, which are absent during cardiac arrest; (3) Nelson’s own studies showed only a loose correlation, not causation; and (4) dream content is typically bizarre and inconsistent, while NDE content is remarkably structured and consistent across experiencers.¹⁶

Temporal Lobe Epilepsy

A form of epilepsy in which seizure activity originates in the temporal lobes of the brain (located on either side of the head, roughly behind the temples). Temporal lobe seizures can produce unusual subjective experiences, including feelings of déjà vu, intense emotions, and, rarely, experiences that have some surface similarity to NDEs (such as a sense of a “presence” or feelings of transcendence). Some researchers, including Michael Persinger, proposed that NDE-like experiences could be triggered by abnormal electrical activity in the temporal lobes. Marsh discusses temporal lobe pathology in chapter 8. However, temporal lobe seizure experiences differ from NDEs in critical ways: they are typically brief, fragmentary, confused, and not veridical. NDEs are extended, coherent, highly structured, and frequently include verified perceptions of the real world.¹⁷

Temporo-Parietal Junction (TPJ)

The region of the brain where the temporal lobe and parietal lobe meet, located roughly above and behind the ear. The TPJ plays a role in how the brain constructs your sense of where your body is in space (body image and spatial self-awareness). Neuroscientist Olaf Blanke demonstrated that electrical stimulation of the TPJ in epilepsy patients could produce brief, partial out-of-body sensations. Critics like Marsh (chapter 6) cite this as evidence that OBEs are simply brain-generated distortions of body image. However, the TPJ-stimulated experiences are fragmentary, inconsistent, often distressing, and never veridical. They are a far cry from the detailed, coherent, verified out-of-body experiences reported in NDEs. Showing that the brain can produce a crude sensation of “floating” does not explain how a clinically dead patient accurately describes events in another room.¹⁸

Terminal Lucidity

The unexpected return of mental clarity and awareness in patients who have been severely cognitively impaired—often by Alzheimer’s disease, brain tumors, strokes, or other conditions that have extensively damaged the brain. Terminal lucidity typically occurs shortly before death (hours to days). Patients who have not recognized family members for years may suddenly become alert, coherent, and emotionally engaged. This phenomenon is a profound challenge to physicalism because it demonstrates that lucid consciousness can emerge even when the neural substrate is severely degraded. If consciousness were entirely produced by the brain, we would not expect a profoundly damaged brain to suddenly generate clear, coherent awareness.¹⁹

Veridical NDE

A near-death experience that includes perceptions of events in the physical world that are later confirmed to be accurate by independent witnesses or records. “Veridical” simply means “truthful” or “corresponding to reality.” Veridical NDEs are the evidential core of this book. While many NDEs include subjective elements (feelings of peace, encounters with light, etc.) that cannot be independently verified, veridical NDEs include specific, concrete details about events in the physical world—details that the patient could not have perceived through normal sensory means and that are later confirmed by others. Examples include accurately describing surgical procedures, identifying objects or people in other rooms, and reporting conversations that occurred while the patient was clinically dead. Holden’s 2009 meta-analysis found that 92% of such reported perceptions were completely accurate.²⁰

Philosophical Terms

The Filter/Transmission Model of Consciousness

A model of the mind-brain relationship in which the brain does not produce consciousness but rather filters, transmits, or receives it—much as a television set receives and displays a signal without generating the broadcast itself. On this view, consciousness is a fundamental reality that the brain channels and focuses, and damage to the brain does not destroy consciousness but rather impairs the brain’s ability to transmit it. This model was first proposed by William James and F. W. H. Myers in the late nineteenth century and has been revived by researchers like Pim van Lommel, Edward Kelly, and Chris Carter. The filter model naturally accounts for NDE evidence: if the brain is a receiver, then when the receiver is impaired or shut off (as during cardiac arrest), consciousness may continue to function—and may even function more clearly, freed from the filter’s constraints. This is exactly what many NDErs report.²¹

The Hard Problem of Consciousness

A term coined by philosopher David Chalmers to describe the fundamental puzzle of why and how physical brain processes give rise to subjective experience. We can explain in great detail which brain areas activate during pain, for example—but this does not explain why it hurts—why there is a felt quality, an inner “what it is like,” to physical brain activity. The hard problem has no widely accepted physicalist solution. Many philosophers and neuroscientists acknowledge that we have no idea how to bridge the gap between objective brain processes and subjective conscious experience. This is relevant to the NDE debate because it reveals a fundamental crack in the physicalist framework: even apart from NDE evidence, physicalism cannot yet explain how the brain generates consciousness at all.²²

Monism

The philosophical view that reality is fundamentally composed of only one kind of substance or stuff. In the philosophy of mind, monism typically refers to the view that human beings are composed entirely of physical matter—there is no separate, immaterial soul. Physicalism (the view that everything is physical) is the most common form of monism in contemporary philosophy and neuroscience. Some forms of monism are idealist (everything is mental) rather than physicalist, but in the context of the NDE debate, “monism” almost always refers to physicalist monism. Monism stands in contrast to dualism.²³

Nonreductive Physicalism

A philosophical position that holds that everything is ultimately physical, but that mental properties (thoughts, feelings, consciousness) cannot be fully reduced to or explained by physical properties. In other words, the mind is not something separate from the brain, but neither is it simply identical to brain activity in a straightforward way. Nonreductive physicalists typically argue that mental properties “emerge” from physical processes but have their own causal powers. In theology, some scholars (such as Nancey Murphy) have adopted nonreductive physicalism as an alternative to both traditional substance dualism and eliminative materialism. This book argues that nonreductive physicalism faces the same fundamental problem as any physicalist view when confronted with NDE evidence: if consciousness depends entirely on the brain (even if it “emerges” from it), then complex conscious experience should not occur when the brain is nonfunctional.²⁴

Physicalism (Materialism)

The philosophical view that everything that exists is physical—composed of matter and energy, governed by the laws of physics. Applied to the mind, physicalism holds that consciousness is entirely a product of brain activity. When the brain dies, consciousness ceases to exist. There is no immaterial soul, no disembodied mind, no consciousness apart from the body. Physicalism is the dominant view in contemporary neuroscience and academic philosophy. It is the view that NDE evidence most directly challenges. If consciousness is entirely a product of the brain, then detailed, coherent, veridical conscious experience during a period of no measurable brain activity should be impossible. The fact that it occurs—repeatedly, across cultures, with verified accuracy—is the central problem that physicalists must address.²⁵

The Production Model of Consciousness

The standard physicalist model of the mind-brain relationship, in which the brain produces or generates consciousness the way the liver produces bile or the stomach produces acid. On this view, consciousness is a byproduct of neural activity and cannot exist without a functioning brain. The production model stands in contrast to the filter/transmission model. NDE evidence challenges the production model directly, because if the brain produces consciousness, then consciousness should cease when brain activity ceases—yet NDEs with veridical elements suggest that it does not.²⁶

Qualia

The subjective, felt qualities of conscious experience. The redness of red, the painfulness of pain, the taste of chocolate, the sound of a trumpet—these are all qualia. Qualia are what make consciousness feel like something rather than being merely an information-processing operation. The existence of qualia is at the heart of the hard problem of consciousness, because physical descriptions of brain activity (neurons firing, neurotransmitters binding to receptors) do not seem to capture or explain the subjective feel of experience. Qualia are relevant to the NDE debate because NDErs consistently report that their experience was not merely informational but deeply felt—often described as “more real than real”—and the vividness and emotional richness of NDE qualia are difficult to reconcile with a malfunctioning brain.²⁷

Substance Dualism

The philosophical view that human beings are composed of two fundamentally different kinds of substance: a material body and an immaterial soul (or mind). The soul is not merely a property of the brain or an emergent effect of brain activity—it is a real, distinct entity that can, in principle, exist apart from the body. Substance dualism was held by Plato (in a strong form) and has been defended in various forms by Descartes, Swinburne, Moreland, and others. The version of substance dualism defended in this book is not Platonic: the soul is not inherently immortal or self-sustaining. God created the soul, and the soul’s continued existence depends entirely on God’s will. The body-soul union is the intended state of human flourishing, ultimately restored in the resurrection. Veridical NDEs provide significant empirical evidence for substance dualism because they demonstrate that consciousness can and does function apart from measurable brain activity.²⁸

Biblical and Theological Terms

Conditional Immortality

The theological view that immortality is not an inherent property of the human soul but a gift of God given only through Christ. On this view, human beings are not naturally immortal—they can be destroyed. Those who are in Christ receive the gift of eternal life; those who finally reject God will ultimately be destroyed (annihilated) after the final judgment, rather than being tormented forever. Conditional immortality is fully compatible with substance dualism: you can believe the soul is a real, immaterial substance while also believing that God can destroy it. This is the eschatological framework of this book. The author affirms that the soul exists and survives death (as NDE evidence suggests) but that final immortality is God’s gift, not an inherent property of human nature.²⁹

Hades (hadēs, Greek)

In the New Testament, Hades refers to the realm of the dead—the place where disembodied souls await the final resurrection and judgment. Hades is not the final state. It is a temporary holding place, roughly equivalent to the Old Testament concept of Sheol. In Luke 16:19–31 (the parable of the rich man and Lazarus), Hades is depicted as having distinct regions—a place of comfort (Abraham’s bosom) and a place of conscious suffering. At the final judgment, Hades itself is emptied and its inhabitants are judged (Revelation 20:13–14). Hades is not the “lake of fire”—the two are distinct in Revelation. The NDE evidence for a conscious intermediate state corroborates the New Testament teaching that persons continue to exist consciously in Hades between death and resurrection.³⁰

Intermediate State

The period between a person’s death and the final bodily resurrection. In Christian theology, the intermediate state is the condition of the soul between the death of the body and the future resurrection. The key question is whether persons are conscious during this interval or are in a state of unconscious “soul sleep.” This book, following the biblical evidence (Luke 23:43; Philippians 1:23; 2 Corinthians 5:6–8; Revelation 6:9–11), affirms a conscious intermediate state: believers go to be with the Lord; unbelievers go to Hades. NDE evidence powerfully corroborates this teaching, because NDEs demonstrate that consciousness can function apart from the body—precisely what a conscious intermediate state requires.³¹

Nephesh (nepeš, Hebrew)

The most common Hebrew word for “soul” or “life” in the Old Testament, appearing over 750 times. Nephesh has a wide range of meanings: it can refer to a living being (Genesis 2:7, “the man became a living nephesh”), to life itself, to the inner self or person, to desire or appetite, or to the throat. Physicalist theologians often argue that because nephesh sometimes means “living creature” or “life,” it does not refer to an immaterial soul. However, as John W. Cooper has shown in Body, Soul, and Life Everlasting, the Old Testament uses nephesh in ways that go beyond mere physical life and that anticipate the later, more explicit, dualist anthropology of the New Testament. The semantic range of nephesh is broad enough to encompass both physical and immaterial dimensions of human existence.³²

Pneuma (pneuma, Greek)

The Greek word for “spirit,” “breath,” or “wind.” In the New Testament, pneuma is used in multiple ways: for the Holy Spirit (the Spirit of God), for the human spirit (the immaterial aspect of a person), and for spirits in general (angels, demons). When used of the human spirit, pneuma often refers to the inner, immaterial core of a person that relates to God and that survives death. In passages like James 2:26 (“the body without the spirit is dead”), pneuma clearly refers to the immaterial component whose departure constitutes death. The human pneuma and the psychē (soul) are closely related and sometimes used interchangeably, though Paul occasionally distinguishes them (1 Thessalonians 5:23).³³

Psychē (psychē, Greek)

The Greek word for “soul” or “life,” the New Testament equivalent of the Hebrew nephesh. Like nephesh, psychē has a range of meanings: it can refer to physical life (Matthew 6:25), to the inner person or self (Matthew 11:29), or to the immaterial soul that survives death (Matthew 10:28: “Do not be afraid of those who kill the body but cannot kill the psychē”). The usage in Matthew 10:28 is particularly important for the dualism debate, because it explicitly distinguishes the body (which can be killed) from the soul (which cannot be killed by human beings but can be destroyed by God). This verse is often cited as the clearest New Testament statement of substance dualism.³⁴

Ruach (rūaḥ, Hebrew)

The Hebrew word for “spirit,” “breath,” or “wind”—the Old Testament counterpart to the Greek pneuma. Ruach appears over 380 times in the Old Testament. It can refer to the Spirit of God (Genesis 1:2), to the human spirit or life-breath (Genesis 6:17; Ecclesiastes 12:7, “the spirit returns to God who gave it”), to wind (Genesis 8:1), or to an attitude or disposition. In the context of human anthropology, ruach often refers to the God-given animating principle that makes a person alive and that returns to God at death. Ecclesiastes 12:7 is a key text for dualist anthropology: it describes death as the separation of the body (“dust returns to the ground”) from the spirit (“ruach returns to God who gave it”).³⁵

Sheol (šeʾōl, Hebrew)

The primary Old Testament term for the realm of the dead. Sheol is depicted as the place where all the dead go—both righteous and wicked (Genesis 37:35; Psalm 89:48). It is described in shadowy terms: a place of silence (Psalm 115:17), darkness (Job 10:21–22), and diminished activity. However, the dead in Sheol are not unconscious or nonexistent: they are described as shades (repha’im) who can be disturbed (Isaiah 14:9–10) and who retain some awareness (1 Samuel 28:15, the spirit of Samuel). The concept of Sheol develops through the Old Testament, and by the intertestamental period, it was understood as having distinct regions for the righteous and the wicked. Sheol is roughly equivalent to the New Testament concept of Hades. The NDE evidence for a conscious state after death is consistent with—and provides empirical corroboration for—the biblical picture of Sheol/Hades as a real realm of conscious, though disembodied, existence.³⁶

Research and Methodological Terms

AVP (Apparently Nonphysical Veridical Perception)

A term coined by Janice Miner Holden (2009) for perceptions reported during NDEs that (a) correspond to objective reality and (b) could not have been obtained through normal physical senses. AVPs are the evidential core of the case for veridical NDEs. Holden’s systematic analysis of 107 AVP cases found that 92% were completely accurate.³⁷

Deathbed Vision (DBV)

An experience reported by a dying person in which they perceive deceased relatives, spiritual beings, or other-worldly environments shortly before death. Deathbed visions are distinct from NDEs in that the person is approaching death rather than being resuscitated from it. The most evidentially significant DBVs are the “Peak in Darien” cases, in which the dying person sees a deceased individual whose death they did not know about. Deathbed visions are discussed in this book as corroborating evidence alongside NDEs.³⁸

Greyson NDE Scale

A standardized research instrument developed by psychiatrist Bruce Greyson (1983) to measure the depth and characteristics of near-death experiences. The scale consists of sixteen questions, each scored 0, 1, or 2, for a maximum score of 32. A score of 7 or above is typically considered to indicate a genuine NDE. The scale measures four clusters of NDE features: cognitive (time distortion, thought acceleration, life review), affective (peace, joy, cosmic unity, light), paranormal (vivid senses, ESP, precognition, OBE), and transcendental (otherworldly environment, deceased persons, border, point of no return). The Greyson Scale is the most widely used NDE measurement tool in the research literature and has been validated across multiple studies and cultures.³⁹

“Peak in Darien” Experience

A type of NDE or deathbed vision in which the dying person encounters a deceased individual whose death was not known to the experiencer at the time. The name comes from a 1882 book by Frances Power Cobbe, who compared the experience to the surprise of the Spanish explorer Balboa when he first sighted the Pacific Ocean from a peak in Darién, Panama. These cases are among the strongest evidence against the wish-fulfillment and expectation hypotheses, because the experiencer had no reason to expect to see a particular person and did not know that person had died. Bruce Greyson published a systematic study of these cases in 2010.⁴⁰

Shared Death Experience (SDE)

An experience in which a healthy, living person present at or near the time of another person’s death reports NDE-like phenomena: leaving the body, seeing a brilliant light, entering a tunnel, encountering deceased relatives alongside the dying person, and so forth. Shared death experiences are uniquely powerful evidence because the experiencer’s brain is not compromised, dying, or in any crisis state. The “dying brain” hypothesis cannot explain why a healthy bystander would have the same experience as a dying patient. Documented by Raymond Moody and William Peters, among others.⁴¹