10 June 2022

Prajñā And Sensory Deprivation

In the two preceding essays, I have explored the role that sensory deprivation (or monotony) might play in Buddhist practice, especially in relation to the threefold path: śīla, samādhi, and prajñā. Sensory deprivation occurs when we are deprived of sensory stimulation. Reading around the topic of sensory deprivation we find, for example, that Oliver Sacks (2012) describes some non-pathological hallucinations that sound identical to experiences described in Kamalashila's (1994) meditation manual. From this I infer that meditation does involve sensory deprivation and that we could interpret the hallucinations that meditators experience as resulting from the same mechanism. However, there is little or no mention of sensory deprivation in the scientific literature on meditation.

Having considered sensory deprivation and meditation, I then went back to reconsider śīla "conduct" in the light of this connection. This allowed me to make a connection with earlier research that showed the Spiral Path formulations to be an elaboration of the threefold path. Various kinds of correct conduct (kusalāni sīlāni) lead, progressively and cumulatively, to joy (pāmojja); joy opens the door to meditation (samādhi), which leads to knowledge and vision; this opens the door to paragnosis (prajñā) "knowledge from going beyond the sensorium". In this view, the whole process of liberation from rebirth is driven by good conduct and a clear conscience.

Lastly, I tried to make a case for the mechanism of non-pathological hallucinations being related to the brain's allostatic mode of functioning. Sensory experience is not simply the brain passively receiving sense stimulation and then reacting. Experience is as much prediction as perception. The brain is constantly active, constantly predicting what will happen next (at the level of patterns of neural activation) and comparing this with inputs in real time. The brain optimises its responses by minimising prediction error. Confronted with a discrepancy, the brain can either change the prediction or change the input (through actions). Past experience is our main guide to minimising prediction errors. Karl Friston has shown that minimising prediction error is mathematically equivalent to minimising the (informational) free energy, and is also (mathematically) related to Bayesian probability (aka The Bayesian Brain hypothesis).

Having dealt with the first two aspects of the threefold path, I now turn to paragnosis. I translate prajñā as paragnosis rather than "wisdom" for a couple of reasons. "Wisdom" is far too vague and seems unrelated to the texts at hand. Conze emphasised the word for the connections it afforded to Greek mystery religions and other esoterica of the type favoured by Madame Blavatsky and company. The English "wisdom" is cognate with vidyā and unrelated to jñā, which is cognate with Greek gnōsis, and Germanic know. My sense is that "wisdom" is simply wrong. Note also that "insight" has long been used to translate vipaśyanā, so that does not seem right, either. I feel it is important to make a conceptual break with that old fraud Conze and his magical thinking. So, having discovered it, I took the Greco-Christian term paragnosis "knowledge from beyond) and repurposed it to mean "knowledge that comes from going beyond the cessation of sensory experience". Repurposing words in a venerable Buddhist tradition that I have sometimes referred "Humpty Dumpty linguistics" (e.g. Attwood 2018a).

Life and Death in Ancient India

Buddhism was formulated during a period of radical socio-political change in India. Around the sixth century before the Common Era, new city-based kingdoms began to emerge from more distributed, village-based societies, resulting in what we call the Second Urbanisation (the first being the urban centres created by the Indus Valley civilisation). It was in and around these cities that religions like Buddhism, Jainism, and Ājivaka-ism were forged and tempered. It was also here that new forms of Brahmanical religion emerged, notably the idea of interiorized rituals that may well have kicked off the whole meditation craze. Buddhism shares many features with other Indian religions, including very often shared stories. For example, elements of the Dhammapāda and the Jātaka appear to have been drawn from a general pool of such stories that were common property and appear in the Mahābhārata.

An important shared feature of Indian religions was/is the cyclic afterlife (reincarnation/rebirth). This is not found in mainstream European cultures so was likely an idea the Indic-speakers picked up from the indigenous peoples they met and merged with  after they arrived in India. Accordingly, reincarnation plays no role in the oldest Ṛgveda stories, but it begins to creep in with the last book to be composed (Book 10). Rebirth features in the Bṛhadāranyaka Upaniṣad, composed around the very beginning of the second urbanisation. Michael Witzel and Signe Cohen (see Cohen 2018) have both argued that BU was composed in the city-state of Kosala, far away from the homeland of the Brahmins in the Punjab. They further suggest that BU reflects the concerns of a breakaway group who had migrated eastwards into the Kosala region and who challenged the hegemony of the Ṛgveda priests.

Another shared feature of different groups at this time was a form of philosophical explanation. In the literature these people left behind, explanations typically rely on analogy, often with nature. In particular, unseen processes are explained by analogy to seen processes. For example, karma is often analogised with growth of a seed into a mature plant. We refer to the consequence of an action as a "fruit" (phala) or as vipāka "ripe, mature". This reliance on analogy is important because I think there is an unspoken analogy at the heart of Buddhist soteriology:

the cessation of sensory experience is like death.

The ancient Indian literature is pre-scientific. The authors did have explanations for things. Some of their explanations are quite systematic, even. But this does not equate to science. For example, ancient Indians appear to have many misconceptions about human reproduction. In ancient Indian thought, a woman is (like) a field, which a man "ploughs" with his penis, planting his "seed" in the form of semen, which then (magically) grows into a human being inside the woman. This agricultural simile is found in both Buddhist and Brahmanical texts. Such similes appear to transcend religious differences, just as cultural ideas like a cyclic afterlife do. But this explanation is based on a raft of misconceptions that were not rightly conceived until the advent of empiricism in the eighteenth century. It took a couple of centuries to arrive at an objective account of human reproduction, and even now there is obviously some confusion amongst religious fundamentalists. 

Similes and metaphors play a central role in these analogies. The basic form of explanation in this: X is like Y, where Y is something that is familiar. In this way any unknown can be, and was, understood with reference to the known. This form of explanation has broad applicability. The explanations that emerge from it are often colourful and entertaining. Considerable creativity has gone into these explanations. We can certainly appreciate the intent and the achievement.

Buddhists themselves were clearly not entirely convinced by early Buddhism, however, since they universally felt they had to change it. And they changed it to the point of being unrecognisable. This includes, by the way, the Theravādins. Having abandoned āyatana practice for jhāna practice, Theravādins eventually also abandoned jhāna for analytical style meditations, and then abandoned meditation entirely for many centuries, before reinventing meditation in the eighteenth and nineteenth centuries. Those who see early Buddhist texts as authoritative are left hanging by the fact that all Buddhist sects moved on, developed and innovated doctrines and practices, and they kept on doing so right down to the present. Buddhisms like Zen or Pureland or Tantric cannot be traced back to early Buddhism. Rather these are inventions of a medieval culture that rejected early Buddhism as a "defective vehicle" (hīnayāna).

In the early Buddhist milieu, human life was widely believed to be cyclic. The basic idea, which one can easily discern in Pāli, is that one is born, lives, and dies in this world (ayaṃ loko), and after death one is born, lives, and dies in the other world (paraṃ loko). Again, this invites agricultural similes as explanations. This cyclic afterlife appears to have been a regional feature of cultures in and around the Ganga Valley. The evolution of this afterlife in Buddhism is described in great detail in Gananath Obeyesekere's book Imagining Karma (2002). The other world split into good destinations (sugati) and bad destinations (duggati), which Obeyesekere attributes to the idea of a right and wrong way to live, i.e. puṇyakarma and pāpakarma. For Buddhists, the ultimate problem was rebirth. Even the best possible rebirth is still problematic. Buddhists, and other religieux of that time and place, all conceived of ending rebirth as the summum bonum of their religion, though they disagreed on how to end it. For Brahmins liberation meant merging back into the eternal and unchanging Brahman, with the loss of all personal identity. For Buddhists it was left undefined: we cannot say anything about a person who escapes from rebirth. They are beyond all conception; neither existent, nor nonexistent.

Given this, we might ask how the cessation and absence of sensory experience would have functioned as the source domain of a cognitive metaphor for Buddhists, in other words, as the basis of an analogy. I say "might" because I don't know for sure, and I'm pretty sure no one else does either. I think what I'm about to say is plausible, given what we do know.

Buddhism and Rebirth

Modern English-speaking Buddhists often talk about rebirth as though it is inconsequential; as though we can just dispense with it. Although I don't believe traditional Buddhist accounts of rebirth any more than I believe traditional Buddhist accounts of human reproduction, I have always tried to acknowledge that from a traditional point of view, Buddhism is completely tied up with rebirth and the ending of rebirth. Fundamentalists see me as apostate, but fundamentalist Buddhism is more of a contradiction in terms than not believing in Iron Age afterlife theories. Even worse, many people seem to think of rebirth as a kind of backdoor to immortality. Europeans tend to see rebirth as a good thing. Buddhism always takes the opposite view, rebirth is the central problem that Buddhism addresses and it does this by eliminating rebirth. The Buddha was not reborn after his death and this caused problems for Buddhism  (but that's another story). 

By the late 1900s, many of the scholars involved in collating and publishing Pāli texts were rationalists in search of a replacement for Christianity, which they saw—in the spirit of the Enlightenment—as hopelessly mired in superstition. In presenting Buddhism to the world in English, they routinely bowdlerised it to fit their own preconceptions. They presented Buddhism as far more rational than it really is. David McMahan drew attention to this in his influential book The Making of Buddhist Modernism. While the concern for rationalism is not universal, it is a powerful current in modernity generally and can be felt in, for example, attempts to claim that Buddhism and science are consistent bodies of knowledge (they are emphatically inconsistent).

I don't know how much of the Pāli suttas would remain if we cut out all the supernatural stuff, all the superstition, myth, and magic. But I want to say about 10%. Something like that. A minority, a small minority, of early Buddhist texts are concerned with objectivity. Indeed, as I have quoted many times, Bodhi says:

“The world with which the Buddha’s teaching is principally concerned is ‘the world of experience,’ and even the objective world is of interest only to the extent that it serves as that necessary external condition for experience.” (Bodhi 2000: 394, n.182)

Buddhism emerged in a culture in which a cyclic afterlife was a given. While there were pockets of different approaches to this issue, the mainstream never doubted rebirth, and Buddhists portray non-believers as wrong-headed and foolish.

There is a complex dynamic that reinforces belief in an afterlife, which I have outlined in this way (see Attwood 2018b)

  • The certainty of the death of individuals creates cognitive dissonance in the self-aware living being.
  • Most of us find the duality of mind and body intuitive because over-active agent detection makes disembodied minds plausible.
  • According to testimony, certain experiences appear to demonstrate that identity and personality are not tied to the body, but can exist independently.
  • The idea that something might survive the death of the body and continue to live seems plausible.
  • Emotional weighting of facts (salience) creates a cognitive bias in favour of the afterlife.
  • Since the finality of death causes intense cognitive dissonance, post-mortem survival seems preferable.
  • We make the leap from probable/preferable to actually true and it feels satisfying because we have resolved the dissonance created by the fact of death and is consistent with our other beliefs.
  • Having made the leap, we fall victim to confirmation bias. We filter incoming information, accepting anything that reinforces our view and rejecting anything that challenges it. The view comes to seem more plausible over time.
  • Our community reinforces our belief, or even makes a profession of the belief a condition of group membership. Believing an afterlife is normative. Apostasy is punished with rejection from the group.
  • Over many generations, the afterlife view is reinforced until it seems to be the only possible view.

So, in thinking about early Buddhism, we have to keep in mind what rebirth is, how it is said to work, and how this belief shaped Buddhist soteriology. But we also have to keep an open mind. We are not compelled to adopt this Iron Age worldview or to treat it as any more grounded than other religious world-views from that time. We are allowed to apply critical thinking to everything, including (especially) religious beliefs.

How, in light of belief in this cyclic eschatology, did Buddhists view death?

Cessation and Death

The cessation of sensory experience is not something I can talk about from personal experience. I haven't undergone cessation. Still, there are many literary and anecdotal accounts of cessation and we can easily grasp the concept. We're all intelligent folk who understand that there is a distinction between our concept of a thing and the thing itself. So let's not get bogged down in anticipating mistakes that none of us make just because that's how Buddhists traditionally conduct arguments (to my enduring frustration).

It's no great stretch of the imagination to say that losing one's sense of self in meditation is a dramatic occurrence (at least the first couple of times). A common comment from people who have undergone this change is that it "feels like death". Interestingly, a recent study of meditation-induced near-death experiences that might shed light on this. William Van Gordon and his team studied meditation-induced near-death experiences (MI-NDE) in 12 intensive meditators. They used a standard definition of NDE and noted reports of them in non-life-threatening situations.

A near-death experience (NDE) is a reported memory of a pattern of experiences that can occur when a person is close to dying (e.g. life-threatening situations, asphyxia, near-drowning, stroke, etc.), when they believe they are close to dying (e.g. shock due to loss of blood) and in the period between clinical death and resuscitation (e.g. due to cardiac arrest) (Van Gordon et al. 2018).

NB: "clinical death" is medical a term indicating the cessation of breathing and blood circulation. But actual death only occurs with the absence of brain activity. There is a short period between the cessation of our heart beat and actual death. No one who is revived was actually dead. They were, in the inimitable words of Miracle Max, "only mostly dead". Although "clinical death" is a term used by medical people, clinical death is evidently not a form of death. Experiences associated with this state are called "near-death experiences", not "actual death experiences". If you are having experiences, even hallucinations, you are not dead. You cannot be dead because dead people don't have experiences. But you might decide, and most people do, that the experiences you had in that near-death state, gave you insights into death.

That Buddhists use meditation to prepare for death is common knowledge. Meditation on death is said to loosen one's attachment to the body, though meditating on death is not always a simple proposition. Compare the mass suicide reported in the Vesālī Sutta (SN 54.9) after the Buddha taught a group of monks to meditate on decomposing corpses. Attachment to being embodied is seen as a major driver of rebirth, and letting go of that attachment is a factor in being liberated from rebirth. But the idea goes further, as Van Gordon et al (2018) suggest:

Thus, in Tibetan Buddhism and to a lesser extent in other Buddhist traditions such as Theravada Buddhism, there exists the view that some advanced meditators can use meditation in order to gain insight into the state of consciousness that manifests after death.

It seems that some meditators are able to voluntarily and intentionally enter a state that substantially overlaps in phenomenology with near-death experiences. And that those who do these practices arrive in mental states that they interpret as death-like, while retaining awareness. Many meditators of my acquaintance solemnly assure me that they know their mind can operate independently of their body. I suspect that this is an artefact of such meditative states. It is worth once again citing Thomas Metzinger on the effects of hyperreal out-of-body experiences:

For anyone who actually had [an out-of-body experience] it is almost impossible not to become an ontological dualist afterwards. In all their realism, cognitive clarity and general coherence, these phenomenal experiences almost inevitably lead the experiencing subject to conclude that conscious experience can, as a matter of fact, take place independently of the brain and body. (p.78)

Meditation can induce hallucinations due to sensory deprivation. And they are likely due to the allostatic mode of the brain.

Van Gordon and company did not consider the impact of sensory deprivation in their study, though it is undoubtedly present and accounts for some of the phenomenology they observed. Indeed, Van Gordon et al have an almost emic approach, perhaps not surprising when the lead investigators are "experienced meditation teachers" as well as neuroscientists. They use the term "spiritual insight" quite a lot for example, but it's not clear what this means. They also use language like this:

A feasible explanation for these observations is that in order to reach advanced stages of meditative development, Buddhist meditators have to embrace the principle of “boundlessness” and seek to transcend relative concepts such as time and space (Van Gordon et al. 2016b).

How is this an explanation, let alone a feasible explanation? What does it mean to label space and time "relative concepts"? It sounds a lot like Madhyamaka metaphysics. Van Gordon et al appear to simply accept the insider accounts of mediation, perhaps because as "experienced meditation teachers" this is the personal orientation as well as the language used by their informants. No attempt is made to decode this Buddhist jargon. Which is fine in a religious text, but out of place in a notionally scientific publication. 

While I don't think the emic orientation of the article vitiates the point it seeks to make, we do have to be cautious of these insider-researchers because they are often setting out to prove something (in a religious epistemic mode) rather than observing what can be observed and adopting whatever the best explanation is.

No one who is primarily concerned with object accounts of the world can possibly take "spiritual insight" seriously as a category (much less when the conclusions take the form of incoherent metaphysical assertions). The problem here is that explanations that draw on meditative traditions are not objective. Such explanations tend to claim that no one can be objective, that there is no objective world, or that the objective world is not real. And none of this is science. Too much credence is given to emic categories and interpretations. Van Gordon et al acknowledge this only in passing under the heading Limitations: "...interpretations of the MI-NDE arising due to religious predispositions were not controlled for." No kidding. Seems like the religious predispositions of the researchers were not controlled for, either.

Despite some limitations, the study conducted by Van Gordon highlights the connection that Buddhists have intuited between meditation and death. The view seems to be that, in meditation, one can rehearse one's death because in death one is cut off from sensory experience. Cessation is like death in that sense. That cessation is often preceded, or accompanied, by the loss of a sense of self only reinforces this interpretation.

The trick is that, for Buddhists and other Indian religieux, death is not connected with the cessation of conscious states, rather is it axiomatic in this worldview that conscious states are not tied to the body and continue on in a disembodied form after death. This intuition about conscious states after death is one that occurs in children. They easily intuit that being dead a person does not need to eat, but they imagine that the dead person will get hungry (c.f. Emmons and Kelemen 2014). That is to say they intuit that their mind is distinct from their body and that this is true for others as well.

I don't think of this as a Buddhist view as such, since this is not how most Buddhist texts talk about it. A notable and influential exception is the Bardo Thödöl or Tibetan Book of the Dead, which is effectively describing reincarnation rather than rebirth. The Bardo Thödöl represents people as having personal continuity in the after-death state.

Note, I've started actively avoiding the term "consciousness" in this context because it is an abstraction. Abstractions are ideas about things, especially things that humans lump together in categories. Categories are also abstractions. This is not problematic, per se, except when we reify the abstraction as most people do with consciousness. It is apparent that almost all non-philosophers and not a few philosophers use the abstract term "consciousness" to refer to an entity; a thing. In this view, consciousness is metaphorically an object. This is why we can think of transferring consciousness from one body to another, whether by rebirth or through "uploading". This why we often talk about a person "having consciousness". In English consciousness can also metaphorically be a container for experience. I've discussed how this cognitive metaphor doesn't seem to appear in Pāli texts. It can be surprising how many people both assert that consciousness is not an entity and that they have experienced disembodied consciousness. In any case, another name for the kind of entity that people associate with "consciousness" is "soul". Europeans are often trying to sneak the soul in the back door of Buddhism.


Since the cycle of rebirths is the central issue of Buddhism, it should come as no surprise that death has long fascinated Buddhists. The contemplation of death, dying, and the decay of a human body are all part of the standard Buddhist collection of techniques. Often they are associated with loosening attachment to one's body, since this attachment to being embodied is seen as a crucial factor in being reborn.

But Buddhists seem to perceive a deeper connection between cessation and dwelling in the absence of sensory experience. The operative cognitive metaphor is: CESSATION IS DEATH. By undergoing cessation, and particularly with the cessation of one's sense of self, one undergoes a kind of death. That is to say, one undergoes an experience, and in seeking to categorise it, Buddhists classed cessation with death. Unlike death, however, cessation and absence do involve awareness. The death of cessation was a kind of death from which one returned with many ideas about what had just happened. The different stories about what cessation reflects, gave rise to a series of religions during the second urbanisation.

The little death of cessation is distinguished from dreamless sleep because one is aware. It is distinguished from dreaming by seeming to be hyperreal and to be hyper-significant. So-called "spiritual experiences" seem to be interpretations of various kinds of hallucinations experienced in the course of withdrawing attention from sensory experience, i.e. in sensory deprivation. Hallucinations arising from sensory deprivation can be seen in the light of the allostatic brain model. The brain expects input and puts a lot of effort into predicting what the next input will be, and then trying to minimise the prediction error through changing expectations or changing the input (through actions).

The combination of neuroscience insights from Metzinger, Sacks, and the others gives us not just an objective explanation of is actually happening during cessation and dwelling in the absence of sensory experience, they also help to explain why meditators start to assert either a dualist metaphysics or a nihilistic metaphysics (Madhyamaka) as a result. These interpretations are what strike people as plausible, not because of the experience per se (since it often has minimal content), but because of the cultural and personal context in which the meditator exists.

If we are lucky enough to have these kinds of rare and unusual experiences, then we inevitably give them the spin that we have been taught to give them. The classic example for me is Gary Weber (especially this interview). Weber describes his awakening in quite sincere and plausible terms. I have no doubt that his experience of the world is now quite different to mine. But Weber sees his experiences as confirming Advaita Vedanta doctrines from medieval India. His interpretation of awakening is very different to Buddhist accounts; though he invokes "emptiness" he doesn't do so in a plausible way (I don't think he understands mainstream Buddhist discourses around emptiness, let alone the Prajñāpāramitā take on it). The same experience can be interpreted in many different ways.

What I have tried to show in these three essays is that sensory deprivation is something that needs to be taken into account when we explain the process and outcomes of meditation. I've tried to show that, though it is not explicitly talked about, there is an awareness of the phenomenology of sensory deprivation in Buddhist texts. This is why Buddhist śīla takes the form it does, rather than the form of ethical treatises, i.e. śīla is primarily preparation for sensory deprivation in meditation and helps smooth the way beyond the destabilising effects of the brain trying to fill in the gaps in predicted experience. Success in meditation is predicated on the brain predicting that nothing is going to happen next. While it predicts something, there is always an unacceptable gap between prediction and present experience.

I have not attempted to be comprehensive. I've consulted a fairly small sample of the literature. Those who do research on meditation would no doubt see this in a different light. We can only hope that the experts do begin incorporate sensory deprivation into their accounts of mediation (though these essays are unlikely to have much impact on that sphere). Whether religieux will do the same remains to be seen. Buddhists are generally averse to deflationary accounts (i.e. accounts which deflate Buddhist exceptionalism).



Attwood, Jayarava (2018a). "Defining Vedanā: Through the Looking Glass." Contemporary Buddhism, 18(3): 31-46. https://doi.org/10.1080/14639947.2018.1450959

——. 2018b. Karma and Rebirth Reconsidered: An Inquiry into the Buddhist Myths of a Just World and an Afterlife. Visible Mantra Press.

Cohen, S. (2019) The Upaniṣads: A Complete Guide. Routledge.

Emmons, N. A. and Kelemen, D. (2014) "The Development of Children’s Prelife Reasoning: Evidence From Two Cultures." Child Development. 2014 Jul-Aug;85(4):1617-33. doi: 10.1111/cdev.12220. Epub 2014 Jan 16.

Gananath Obeyesekere (2002) Imagining Karma: Ethical Transformation in Amerindian, Buddhist, and Greek Rebirth. University of California Press.

Kamalashila. (1994). Meditation: The Buddhist Way of Tranquillity and Insight. Windhorse Publications.

McMahan, David. (2008) The Making of Buddhist Modernism. Oxford University Press.

Sacks, Oliver. (2012). Hallucinations. Picador.

Van Gordon, W., Shonin, E., Dunn, T.J. et al. (2018) "Meditation-Induced Near-Death Experiences: a 3-Year Longitudinal Study." Mindfulness 9: 1794–1806. https://doi.org/10.1007/s12671-018-0922-3

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