Here you will find some useful, interesting, and inspiring resources to support your understanding as you read through the textbook.

Chapter 1: What’s the problem?

Chapter Summary

The problem of consciousness relates to what the world is made of, how it began, the nature of selves, and above all the mind-body problem. In philosophy, dualism is the idea that mind and matter are distinct – a common belief in most societies and religions. In Cartesian dualism (described by René Descartes) mind and matter are separate substances. Objections to this, and other forms of dualism, are discussed, including Dennett’s mythical Cartesian theatre. Alternatives include materialism, idealism, and neutral monism, as well as epiphenomenalism, supervenience, panpsychism, and theories based on mind as brain in action.

In science, nineteenth-century psychophysiologists conducted experiments on sensation, perception, and memory, and William James promoted an empirical psychology based on their findings. By contrast, European phenomenologists concentrated on methods for putting subjective experience first. But difficulties with introspection helped pave the way for behaviourism, which rejected all talk of subjective experience.

Discussion of consciousness returned to psychology in the late twentieth century, initially concentrating on brain studies but later branching out into embodied cognition. Yet the mind-body problem, or the ‘explanatory gap’, remains. In 1994 David Chalmers coined the phrase ‘the hard problem’ of consciousness, to be distinguished from the ‘easy problems’ tackled by most of psychology.

Suggested film:

2001: A space odyssey, dir. Stanley Kubrick (1968): based on a short story by Arthur C. Clarke and co-written by Clarke and Kubrick, it will make you question human consciousness on a cosmic scale

Suggested literature:

Nausea (La nausée), Jean-Paul Sartre (1938) (if you’re reading in translation, go for the one by either Robert Baldick or Lloyd Alexander): part novel, part existentialist tract, told through the diaries of a man who comes to question everything


The hard problem of consciousness: David Chalmers and Sam Harris interview (1:33:07)

Susan Blackmore: The mystery of consciousness (Ratio BG) (58:48): includes material on visual perception and free will, and how looking into our own experience might change our intuitions

Cartesian dualism (Philosophy Tube) (8:27)

The secrets of consciousness (IAI TV) (47:16): a debate at HowTheLightGetsIn Festival, Hay-on-Wye, May 2018, with Sue Blackmore, Nicholas Humphrey, and Philip Goff, chaired by Barry Smith and including lots about panpsychism

The metaphysics of panpsychism (Alfred North Whitehead Project) (40:20): collage of clips and quotes from major thinkers on consciousness

William James his life and philosophy (Wes Cecil) (1:08:58): James’s family upbringing and the development of his thought

Does consciousness exist? By William James (50:26): reading of an essay from James’s Essays in Radical Empiricism, on the problems of thinking about consciousness

Husserl & the adventure of phenomenology – in 12 minutes (Eric Dodson) (11:48): the basics of the concepts and methods of phenomenology

Husserl & phenomenology (Philosophical Overdose) (56:21): Robert Harrison interviews Thomas Sheehan, starting with the origins of phenomenology in a Parisian bar where Jean-Paul Sartre, Simone de Beauvoir, and Raymond Aron sat drinking apricot cocktails

Behaviorism: Pavlov, Watson, and Skinner (Alana Bennett), Part I and Part II (4:57 and 5:05): the basics of behaviourist conditioning and reinforcement

B. F. Skinner – philosophy of behaviorism (1988) (45:27): interview with Skinner about the behaviourist perspective on mind

Foundations: Skinner (YaleCourses) (58:46): lecture by Paul Bloom linking the unconscious and behaviourism

Foundations: Freud (56:30): Paul Bloom on Freud’s ideas, including about the unconscious


David Chalmers thinks the hard problem is really hard (John Horgan): how the hard problem was born, and what it means to Chalmers

The mind–body problem, scientific regress, and Woo (John Horgan): the lack of progress in consciousness science since 1994

The real problem (Anil Seth): an alternative to the hard problem

Chapter 2: What is it like to be . . .?

Chapter Summary

Although there is no recognised definition of consciousness, many researchers refer back to the famous question, ‘What is it like to be a bat?’. If there is anything it is like for the bat, that is what is meant by being conscious. This is also called ‘phenomenal consciousness’ (P-consciousness) or ‘phenomenality’ and is sometimes contrasted with ‘access consciousness’ (A-consciousness). Problems with this distinction are discussed. Philosophers refer to specific conscious experiences (like the colour red or the smell of coffee) as ‘qualia’, although this concept is also disputed. Some well-known thought experiments are used to illustrate these debates, including ‘Mary the colour scientist’ (who knows all the physical information about colour vision but has never left her black-and-white room) and the ‘Philosopher’s zombie’: a creature that is physically indistinguishable from a normal person but has no conscious experiences. This zombie is clearly conceivable, but is it possible? The many arguments about this are reviewed. We then return to the hard problem and possible responses to it: 1) The hard problem is insoluble, 2) We must try to solve it, 3) We should tackle the easy problems, 4) We should find more hard problems, 5) There is no hard problem.

Suggested TV series:

Westworld, created by Jonathan Nolan and Lisa Joy (2016–): based on the 1973 film written and directed by Michael Crichton, about a Wild West theme park in which high-paying guests interact with android hosts

Suggested literature:

Thinks . . ., David Lodge (2001): a campus novel about consciousness, told largely through the diaries of a novelist and the recorded monologue of a professor of cognitive science who hopes to seduce her


What is it like to be a bat (Existentialist Dasein) (6:04): an account of Nagel’s paper, with bat pictures

Daniel Dennett – a phenomenal confusion about access and consciousness (Richard Brown) (1:06:17): P/A consciousness, seeming and ‘real seeming’, figment, and other topics

Thoughts about thought experiments (PBS Idea Channel) (5:12): why we do thought experiments at all – though arguably misinterprets Dennett’s notion of the ‘intuition pump’

Daniel Dennett discusses a bad thought experiment (Big Think) (6:23): how profoundly the tiny narrative details of a thought experiment can affect the outcome

Mary’s room: A philosophical thought experiment – Eleanor Nelsen (TEDEd): includes video (4:51) plus prompts for reflection and discussion

SOMA: The philosophical zombies – monsters of the week (RagnarRox) (11:03): how a video game prompts us to explore the possibility of our own and others’ zombiehood

Zombie and Mary (Baba Brinkman) (2:02 and 3:14): rapping about hip-hop zombies and a deaf scientist of rap (view the full album, The Rap Guide to Consciousness, here)


Qualia (Internet Encyclopedia of Philosophy): how the concept relates to some of the major theoretical positions in consciousness studies

Zombies on the web: how to identify a Hollywood zombie, a Haitian zombie, and the philosophical kind, plus many zombie-related resources collected by Dave Chalmers

Chapter 3: The grand illusion

Chapter Summary

We may have powerful intuitions about our own minds, but they must be questioned. Could vision, consciousness, self, and free will all be illusory – meaning that they are not what they seem? This chapter concentrates on whether vision is a ‘grand illusion’. This idea emerged from research on ‘change blindness’, which found that even large changes in an image can go unnoticed if made when the image is moved (to force an eye movement) or a brief flash is inserted (to mimic a blink). In ‘inattentional blindness’ people can miss events they are looking directly at if they are not paying attention. Magicians have long used these effects to trick people. The vexed question of ‘filling-in’ arises when part of an object is obscured by another or when part of the scene falls on our blind spot. Does the brain ‘fill in’ the missing details? Does it need to? Evidence pointing both ways is reviewed and opposing theories considered, including enactivist and sensorimotor theories, which treat seeing as a form of action. These ideas and discoveries all challenge the intuitive idea that visual consciousness involves building up a rich picture of the world inside our heads.

Suggested films:

The prestige, dir. Christopher Nolan (2006): adapted from the novel by Christopher Priest about two obsessively competitive magicians, the film subjects its audience to multiple sleights of hand too

Suggested literature:

The castle (Das Schloss), Franz Kafka (1926) (ideally in the translation by Mark Harman): from the opening scene, where a man stands on a bridge and looks up at an invisible castle, this unfinished novel plays games with the characters’ and our own perception: profound gappiness, change and inattentional blindness, and the effects of emotion on perceptual experience contribute to a deeply strange-seeming realism. (You could also read this article by Emily on perception, time, and ‘cognitive realism’ in works by Kafka, including The Castle.)


Movie mistakes: When does film continuity REALLY matter? (This Guy Edits) (8:18): directors’ and psychologists’ views on whether to care about continuity errors

Optical illusions show how we see | Beau Lotto (TED) (18:59): why context is everything in why we see what we do and what that means for who we are

Alva Noë – why is consciousness so baffling? (Closer To Truth) (11:29): why we need to take the body and environment more seriously in trying to understand consciousness; see also another excerpt from the same interview, here, on why the hunt for the NCCs is mistaken, and why computational models of mind and the idea of neural representation can lead us astray

Kevin O’Regan: The sensorimotor approach to understanding ‘feel’ in humans and robots (SoftBank Robotics Europe) (38:18): the sensorimotor alternative to neurocentric accounts of sensory consciousness, and why there is nothing to stop robots having real feels

Why things feel the way they do: The sensorimotor approach to understanding phenomenal consciousness (Copernicus Center for Interdisciplinary Studies) (1:01:33): O’Regan gives a fuller account of the sensorimotor perspective

The illusion of consciousness | Dan Dennett (TED) (23:45): real magic, the magic that can actually be done, is not ‘real magic’, just ‘conjuring tricks’; lots of people think the same about consciousness, so don’t actually want it explained

Apollo Robbins magic of consciousness (MagicMitch) (14:56): how attentional control affects perception of the magic – and lots of nice examples of magic in action


Change blindness demonstrations: a collection of change blindness and inattentional blindness demos compiled by Kevin O’Regan

Visual phenomena & optical illusions: 132 illusions with instructions and scientific commentary, collected by Michael Bach

Chapter 4: Neuroscience and the correlates of consciousness

Chapter Summary

Can the brain tell us everything we need to know about consciousness? Some materialists say yes, while theorists of ‘extended mind’ and ‘embodied cognition’ criticise ‘neurocentrism’ and say no. Mysterians claim that we can never understand consciousness at all. This chapter briefly reviews the anatomy and function of the human nervous system, from spinal cord to neo-cortex. In searching for the ‘neural correlates of consciousness’ (NCCs) researchers hope to find those brain areas, networks, or processes that give rise to consciousness as opposed to those that do not – remembering that a correlation does not necessarily imply causation and that there may not be a ‘magic difference’ between conscious and unconscious brain processes. The differences between P-consciousness and A-consciousness, and between the correlates of ‘consciousness itself’ and its contents, are discussed. Classic experiments with binocular rivalry in both monkeys and humans are reviewed, exploring the idea of processes ‘competing for consciousness’. A different approach is to study brain activity in states of reduced consciousness, including ‘locked-in syndrome’, ‘persistent vegetative state’, and coma, as well as the effects of anaesthesia. The known neural correlates of pain forcefully expose the problem: why should the firing of certain groups of neurons actually hurt?

Suggested TV episode:

‘Locked in’ (House) (season 5, episode 19), dir. Dan Attias (2009): much of this episode in the medical drama is shown from the perspective of a locked-in patient (played by rapper Mos Def) as the team try to work out a diagnosis

Suggested literature:

The man who mistook his wife for a hat, Oliver Sacks (1985): beautifully written case histories about people with a range of neurological disorders

The diving bell and the butterfly (Le scaphandre et le papillon), Jean-Dominique Bauby (translated by Jeremy Leggatt) (1997): the author suffered a massive stroke that left him with locked-in syndrome and wrote this book (about his former life as a magazine editor and his new life in hospital) by blinking his left eyelid as a transcriber recited a frequency-ordered alphabet, for four hours a day for ten months and at an average rate of two minutes per word

In the land of pain (La doulou), Alphonse Daudet (edited and translated by Julian Barnes) (1930/2002): a translation of a posthumously published collection of detailed, probing, often humorous notes on the experience of slowly dying of syphilis


Neural correlates of consciousness・Disorders of conscious perception lecture 1 (Melanie Wilke) (計算科学eラーニングアーカイブチャンネル) (19:43): categories and causes of loss of consciousness; see lectures 2 and 3 on treating such disorders of consciousness and prerequisites of consciousness, and on qualia and the brain

Neural basis of binocular rivalry (SeanBurn88) (8:29): an overview of evidence and theories

Disorder of consciousness & cognitive recovery following TBI levels 1-3 (Craig Hospital): a video aimed at relatives of those affected, illustrating how traumatic brain injury affects consciousness and responsiveness, with footage of patients at different points in recovery (the sequels on Levels 4–6 and 7–10 cover later stages of rehabilitation)

Locked-in syndrome: Nick Chisholm (Attitude) (29:00): follows Nick and his partner through their daily life following his stroke, including his bodybuilding training as part of rehab

The mystery of consciousness and the vegetative state | Martin Monti (TEDx Talks) (15:58): ways of clinically establishing presence of consciousness in comatose patients

Anesthesia and consciousness, Stuart Hameroff (scienceandnonduality) (5:13): how consciousness changes with anaesthesia and near death

Mind perception: Unravelling the mysteries of the brain and mind in the aftermath of Terri Schiavo and related cases (FABBS Foundation) (28:11): the difficulties of assessing consciousness in anaesthesia and other clinical conditions

Pain and the brain (University of California television) (1:27:42): the (neuro)biology underlying pain, and how to investigate and treat pain

Chapter 5: The theatre of the mind

Chapter Summary

The metaphor of mind as a theatre is common and alluring, but might it lead us astray? Dennett criticises those who imagine a ‘Cartesian theatre’: a mythical place in which consciousness happens and its contents come and go. This cannot exist because the brain is a massively parallel system with no centre, place, or process where the ‘audience of one’ could be. Those who believe in it he calls ‘Cartesian materialists’. This chapter explores the value and pitfalls of the theatre metaphor. Experiments on mental rotation, and similarities between imagery and visual processing, are reviewed. The ‘great imagery debate’ between pictorialist and propositionalist (language-like) theories is explored, along with challenges to both positions from enactivist and sensorimotor theories. Several theories of consciousness explicitly entail theatres, especially Global Workspace Theory (GWT) and neuronal GWT. Others dispense with theatres, including the deeply counterintuitive ‘multiple drafts theory’, which does away with any distinction between things that are ‘in’ or ‘out’ of consciousness. ‘Integrated Information theory’ and some quantum theories also avoid theatres but raise other difficulties. For each theory we ask whether it entails a Cartesian theatre, explains subjective experience, and accounts for (or rejects) the difference between conscious and unconscious processes.

Suggested film:

Being John Malkovich, dir. Spike Jonze (1999): a puppeteer finds a doorway into John Malkovich’s head, and turns it into a money-making scheme: people pay for fifteen minutes inside Malkovich, and eventually Malkovich even uses the portal himself

Suggested literature:

‘The love song of J. Alfred Prufrock’, T. S. Eliot (1915): in this poem, apparently about the anxieties of a middle-aged everyman, most critics interpret ‘you’ and ‘I’ to be different parts of the speaker’s nature, with the dominant ‘I’ corresponding to the ‘true’ self who lives inside the head, and the ‘you’ referring to the ‘external’, ‘false’ self perceived by others


Cartesian Theatre – Daniel Dennett (silverstream314) (5:27): a quick summary of why the CT is conceptually and empirically untenable, with a little help from Men in Black and a deviation into the idea of the soul

The imagery debate: The role of the brain (MIT OpenCourseWare) (55:11): Stephen Kosslyn’s overview of the twenty-five years of his work on imagery

Bernard Baars – The biological basis of conscious experience: Global workspace dynamics in the brain (Richard Brown) (46:56): sets out the basics of GWT

Stanislas Dehaene – There’s nothing magical about consciousness (11thstory) (21:26): a brief account of neuronal GWT, including reflections on dualism, qualia, the self, artificial consciousness, and the dangers of intuition

Patricia Churchland on eliminative materialism (LennyBound) (9:22): how the combination of neuroscience, psychology, and philosophy can offer alternatives to folk–psychological concepts of mind

Sir Roger Penrose – The quantum nature of consciousness (2045 Initiative) (7:08): why computational theories don’t work, and the quantum alternative

The future of consciousness: Stuart Hameroff at TEDxTucson (TEDxTalks) (10:48): sets out the Orch OR theory

Daniel Dennett – How are brains conscious? (Closer To Truth) (12:18): fame in the brain is what it means to be conscious (7:13 onwards on multiple drafts)


A new spin on the quantum brain (Jennifer Ouellette): focusing on how Matthew Fisher came to the idea that phosphorus might be the basis for storing quantum information in the brain

‘The talk’ by Scott Aaronson and Zach Weinersmith: a comic strip on talking to your kids about quantum computing


.projekt: a minimalist and literally mind-bending game of mental rotation, also available for mobile

Chapter 6: The unity of consciousness

Chapter Summary

We feel ourselves to be one united self, experiencing one stream of consciousness at a time, yet look inside the brain and we find a parallel system of great complexity and diversity. The ‘binding problem’ concerns how the features of an object are brought together. For example, different parts of the visual system deal with colour, shape, and movement, but these must all be brought together for us to see one moving object. Different senses must also be united by ‘multisensory integration’. Time is also a problem because different brain processes operate at different rates and subjective and clock time must be integrated with each other. Among possible solutions are binding by synchrony, the theory of micro-consciousness, and Integrated Information Theory (IIT). Enactivist theories point out that the whole organism is intrinsically united through its actions; illusionist theories claim that the unity of consciousness is an illusion and we need to ask how the illusion comes about. Finally, this chapter explores what happens when consciousness is more or less unified than normal, using examples from synaesthesia, split brains, amnesia, and hemifield neglect. These atypical cases may make us question what we assume about normal experience.

Suggested film:

Synesthesia, dir. Terry Timely (2009): a short film about a family’s surreally matter-of-fact routines involving food–music synaesthesia and other intertwinings of sensory, cognitive, and material pathways

Memento, dir. Christopher Nolan (2000): the story of a man with no short-term memory, told backwards

Suggested literature:

The notebooks of Malte Laurids Brigge (Die Aufzeichnungen des Malte Laurids Brigge), Rainer Maria Rilke (1910) (translated by Stephen Mitchell, Burton Pike, or Robert Vilain): a fragmented modernist–expressionist tale of a young man who comes to Paris and describes himself, in his diary, as ‘learning to see’


The curious world of synaesthesia | Jamie Ward | TEDxCambridgeUniversity (Tedx Talks) (13:02): the constant interactions between senses, including the specific case of synaesthesia

Seeing sound, hearing light . . . welcome to synaesthesia | Danne Stayskal | TEDxSalem (Tedx talks) (10:12): a personal account of polymodal synaesthesia, and a modified guitar to let us see the music in colour too

Giulio Tononi on consciousness and integrated information theory (Jah Tzu) (20:25): a round-up of what the theory tries to account for, and how

Two minds in one brain (World Science Festival) (6:53): Giulio Tononi, actor–author–director Alan Alda, and filmmaker Charlie Kaufman discuss split-brain phenomena and their relation to artificial consciousness

Interview with Michael Gazzaniga and split brain patient ‘Joe’ (markmcdermott) (10:14): Joe’s performance in drawing and recognition tasks reveals how the hemispheres are interacting

The man with the seven second memory (medical documentary) (Real Stories) (48:00): a film about former musician and conductor Clive Wearing, who suffered a virus causing massive brain damage that resulted in profound amnesia, and describes what the absence of consciousness is like to live with

A visual neglect patient (cogmonaut) (3:18): drawing tasks based on vision and memory demonstrate a woman’s unilateral neglect, and her awareness of it – as discussed by Ramachandran and Peter Halligan

Consciousness is a narrative created by your unconscious mind | Dean Buonomano (Big Think) (4:19): various temporal phenomena suggest the ‘unconscious mind’ processes things nonlinearly, but creates a linear narrative for the ‘conscious mind’ to enjoy


A ‘complex’ theory of consciousness (Christof Koch): an accessible account of IIT

Can integrated information theory explain consciousness? (John Horgan): account of an IIT workshop, with discussion of some of the theory’s sticking points

Chapter 7: Attention

Chapter Summary

Directing attention may feel like pointing a spotlight, but what is happening in the brain and how does attention relate to consciousness? Two broad types of attention are controlled by different brain systems: the dorsal (voluntary) and ventral (involuntary) attention systems. Theories of attention are reviewed, including bottleneck or filter theories, early- and late-selection theories, pre-motor theory, attention as preparation for action, biased competition theory, and theories treating short-term memory as a resource to be competed for. In ‘attention schema theory’ consciousness is an organism’s internal model of attention, so how does attention relate to consciousness? We consider five possibilities: 1) Consciousness depends on attention, 2) Attention depends on consciousness, 3) Consciousness and attention are correlated but not causally connected, 4) There is no link between the two, 5) Both are illusory.

Meditation and mindfulness are ways of training the attention. We consider the basic principles, including open and concentrative meditation, and mindfulness in daily life. Research on both short- and long-term practice is reviewed, including effects on the ‘default mode network’. Training attention clearly changes consciousness but the relationship between the two remains an open question.

Suggested film:

Silver blaze (The Return of Sherlock Holmes), dramatised by John Hawkesworth (1988): paying very particular kinds of attention, Jeremy Brett’s Holmes investigates the disappearance of a champion racehorse and the murder of its trainer, also uttering the now-famous line about the curious incident of the dog in the nighttime

Suggested literature:

Mezzanine, Nicholson Baker (1988): an office worker spends his lunch hour subjecting his everyday world to comically minute attention


Michael Graziano: Consciousness and the attention schema (Richard Brown) (38:57): attention schema theory as a way of tackling the questions of how we attribute the property of awareness to other people, and how the brain might attribute awareness to itself

Cognitive neuroscience of mindfulness meditation (GoogleTechTalks) (48:53): Philippe Goldin discusses how meditation affects mindfulness, attention, and neural systems, and the clinical applications of MBSR for social anxiety disorder


Attention and consciousness (Naotsuga Tsuchiya and Christof Koch): a different way of doing something similar to what our chapter tries to

Meditative states as feedback loops (Slate Star Codex): why positive feedback doesn’t always prevail, and what happens when it does

Additional material from 2nd edition:

Here are a few tips about the practicalities of how to meditate. You could see Sam Harris’s page on ‘How to meditate’, including some guided meditation podcasts, for more suggestions.


Posture. Meditation usually involves sitting in a special posture, but there is nothing mysterious about this. The postures all serve to keep the body both alert and relaxed, while keeping still for long periods. It is possible to meditate in any position at all, and Transcendental Meditation involves just sitting comfortably in a chair, but the two main dangers are becoming too tense and agitated, or falling asleep. The traditional postures help to avoid both.

The best known is the full lotus position. This provides a stable triangle of contact with the floor, and a relaxed posture with an upright spine that takes little physical effort to maintain. It also encourages breathing from the abdomen rather than just the chest, and the depth and speed of breathing are known to affect heart rate and blood pressure and hence blood flow to the brain. However, the full lotus is difficult for people who are used to sitting in chairs, and not worth struggling with if it is painful. Unnecessary pain, and showing off, are not helpful for meditation. There are many other postures that achieve the desired stability and alertness, including the half lotus and the simpler Burmese position. Many people sit on low benches with their knees on the ground and their back straight. Sitting in a chair is less stable but is the best option for some; you should place your feet apart on the floor to give stability, and keep your spine rising lightly upwards and away from the back of the chair.

During long meditation retreats, sitting is sometimes alternated with very slow walking meditation, or even fast walking or running meditations, to give the body some exercise and stimulation without disturbing the practice. In fact, meditation can be done in any position at all, and for some traditions the ultimate aim is to integrate meditation into all life’s activities.

Some traditions advocate particular ways of holding the hands, including resting them gently on the knees either palm up or palm down, resting in the lap, and holding various gestures associated with compassion, openness, or other desired qualities. Some use repetitive movements such as repeatedly touching the tips of the four fingers on the thumb. There is no research on the effect of specific hand positions, but it is possible that they make a difference as a reminder of the intended state of mind or by manipulating the body image.

Chapter 8: Conscious and unconscious

Chapter Summary

Is the age-old distinction between the ‘conscious mind’ and ‘the unconscious’ valid, or do powerful, but false, intuitions mislead us? Unconscious, implicit, or subliminal perception is reviewed, from early ideas of a ‘subliminal self’ to modern debates over subliminal perception, including signal detection theory, priming, and the differences between objective/subjective and direct/indirect measures. Emotional and social effects are explored along with their brain basis. The core question is: does consciousness have causal efficacy? Causal theories include varieties of dualism, global workspace theory, and neuronal GWT. Non-causal theories include eliminative materialism, epiphenomenalism, ‘higher-order thought’ theories, and some forms of functionalism. One key observation is that actions can happen too fast for conscious visual perception to be involved. Research on visual guidance, fast motor control, the effects of brain damage, and the strange phenomenon of blindsight, suggests that fast actions are controlled by the visual dorsal stream, and the perception of objects and events by the slower ventral stream. The chapter ends by exploring the role of consciousness in intuition and creativity. The research reviewed challenges the common assumptions that perceptions must be either ‘in’ or ‘out’ of consciousness, and that actions must be performed either consciously or unconsciously.

Suggested film:

The enigma of Kaspar Hauser (Jeder für sich und Gott gegen alle, lit. ‘Every man for himself and God against all’), Werner Herzog (1974): in the early nineteenth century, the real Kasper Hauser appeared in a square in Nuremberg, having lived all his life alone in a dark cell; this film follows him as he learns everything – how to walk, how to speak – from scratch; as he creates a life where he has no sense of one

Suggested literature:

Death in Venice (Der Tod in Venedig), Thomas Mann (1912) (ideally in the translation by Michael Henry Heim): a novella about a man who devotes his life to silencing instinct and passion, and is finally overcome by them


Subliminal perception (Derren Brown) (7:02): magician Derren Brown turns the tables on the advertisers

Higher-order theories of consciousness (Philosophical Overdose) (1:16:15): a conversation between Pete Mandik and Richard Brown, including discussion of zombies, problems with other existing theories, and why higher-order theories have more potential

What is functionalism? (Philosophy of Mind) ( (5:28): clarifies the position in relation to consciousness

Mel Goodale – ‘Visual routes to knowledge and action: (almost) 25 years of two visual systems’ (PsyNeuroEvents) (1:09:56; starts at 4:09): a broad account of the distinction between vision for action and for perception

Blindsight (Coolpsychologist) (5:41): Christof Koch and Jochen Braun present an experiment simulating blindsight in people with normal vision, with concluding reflections on unconscious vision from Mel Goodale

The deeper self: A deeper view of consciousness (1:17:37): writer Siri Hustvedt, Jungian scholar Sonu Shamdasani, and neuropsychoanalyst Mark Solms discuss the past and present of thinking about intuition, creativity, and the unconscious


What if consciousness is not what drives the human mind? (David Oakley and Peter Halligan): argues that the ‘contents of consciousness’ are generated by non-conscious brain systems, and take the form of a constantly updated personal narrative. The authors consider the implications of this account for evolutionary adaptation and free will and personal responsibility, and link to a fuller exploration of these ideas in their Frontiers in Psychology paper.

Additional material from 2nd edition:

This activity may help you explore the question of whether consciousness has causal efficacy in a group setting.

Activity – Does consciousness do anything?

Get into pairs, or small groups, or ask two volunteers to do the exercise in front of the whole class. The task is this: the first person suggests an example of something that consciousness does. They might say, for example, that a conscious decision made them get up this morning, or that consciousness helps them play computer games, or that they could not fall in love without it. The second person then refutes the suggestion as thoroughly as possible.

Proposers should try to come up with a specific example rather than generalities. The refuter must then try to explain the action or decision without requiring consciousness in the explanation. For example, they might use behaviourist arguments, or call on the influence of genes or education.

Note that you do not have to believe your own arguments. Indeed, it may be more useful to put forward arguments you do not believe in. So, if you are the proposer and you think that consciousness does nothing, you should still invent some example that other people might think requires consciousness. If you are the refuter, you may actually believe that consciousness is required for the proposed action, but you must do your best to find a way out. This will sharpen up your beliefs about the causal power of consciousness. Don’t agonise over your arguments. It does not matter if they are wrong, or fanciful. The point is to throw up some ideas to think about.

Finally, discuss what you have learned. Was there any proposal which no one could knock down? Did you find some irrefutable thing that consciousness is required for? Were there patterns in the suggestions people came up with?

Can you now answer the question ‘What does consciousness do?’ You might like to write down your own answer at this point, or make your own list of things that you think consciousness does. It is likely to change.

This activity may complement the Concept box on sensory substitution.

Activity – Blind for an hour

This is a simple exercise designed to give a hint of what it is like to be blind. You need to work in pairs and can take it in turns to be blindfolded or to be the guide. You need a good blindfold that does not allow you to peep. It is possible just to wear dark glasses and to keep your eyes closed, but the temptation to open them is too great for most people, so a blindfold is easier.

Take an hour for the exercise and plan what you will do. For example, you might go shopping, or take a walk, or go to a party or visit friends. Try to do as much as you can without help, but be careful to avoid dangerous activities such as cooking. Your guide must take responsibility for crossing roads and other obvious dangers, and should stay close to you all the time.

Afterwards, think about what surprised you. Which things were easier or more difficult than you had expected? What happened in social situations?

If you are blind, this exercise is no use to you, but you can be of great help to others. You might teach them to use a long cane, discuss the ways in which you negotiate different situations without vision, or explain how other people can help or hinder your independence.

For a devastating and revealing description of what it is like to go blind, see Hull (1990).


Hull, J. M. (1990). Touching the rock: An experience of blindness. London: Arrow Books.

Here is a little more detail on the notion of ‘flow’ covered briefly in the main text.

Concept – Flow

When athletes, musicians, scientists, or chess masters are deeply engrossed in their favourite activity, they sometimes enter an ‘optimal state of experience’ in which time and self disappear and everything seems to flow. This special state was studied by Chicago psychologist Mihaly Csikszentmihalyi, after he had worked extensively with a group of artists. Sometimes they worked for hours on end, deep in concentration, as though their painting was the most important thing in the world, but when it was finished they would put it away and not even look at it again. For these people, painting was intrinsically rewarding, unlike the extrinsic rewards of fame, riches, or even the completed work. The reward of all this hard work was the activity itself.

Csikszentmihalyi (1975) discovered that finding flow depends on getting the right balance between the challenge a person faces and the skills they bring to tackling it. When something is too difficult, you feel anxiety; when it’s too easy, you get bored. But when challenges and skills are perfectly matched, flow can arise. The challenge can be any opportunity that a person is capable of responding to, from the vastness of the sea in sailors, to maths homework in school children; from concluding a successful business deal, to enjoying a happy relationship. As a person improves in skill, the challenge has to increase, so to find that flow again the player has to find a better opponent, and the mountaineer a more difficult climb. When we are tired or ill or ageing, we must find challenges that match our lesser skills. But having once experienced flow, people are keen to find it again. Flow forces people both to stretch themselves, and to know themselves.

Flow has been studied in Japanese motorcycle gangs, surgeons, prisoners in solitary confinement, and women at work (Csikszentmihalyi and Csikszentmihalyi, 1988). In all cases people describe similar experiences. They are so deeply engrossed that action and awareness seem to merge into one. Time loses its meaning as hours seem to slip by in moments, or moments seem to last forever. It is an experience in which ‘all the contents of consciousness are in harmony with each other, and with the goals that define the person’s self’ (1988, p. 24). ‘In flow the self is fully functioning, but not aware of itself doing it [. . .]. At the most challenging levels, people actually report experiencing a transcendence of self’ (p. 33). The skier feels at one with the slope, the turns, the snow, and the fear of falling. ‘The mountaineer does not climb in order to reach the top of the mountain, but tries to reach the summit in order to climb’ (p. 33).

Although flow is usually described as a state of consciousness, it might better be described as a state in which the distinctions between conscious and unconscious processing disappear. Something about bringing all our skills into action seems to annul any sense that there is even a self to be conscious.


Csikszentmihalyi, M. (1975). Beyond boredom and anxiety. San Francisco: Jossey-Bass.

Csikszentmihalyi, M., and Csikszentmihalyi, I. S. (Eds) (1988) Optimal experience: Psychological studies of flow in consciousness. Cambridge: Cambridge University Press.

Chapter 9: Agency and free will

Chapter Summary

Are we really free when we choose our actions? The major religions rely heavily on the concept of free will and most people believe in it, but there are serious problems. First we review the neuroanatomy of volition: the networks involved in internally and externally triggered actions and in decision-making.  Libet’s ‘half-second delay in consciousness’ is discussed, along with his concepts of ‘backwards referral’ and ‘neuronal adequacy’, and his ‘time-on’ theory of consciousness, with its external ‘mental force’. Libet’s later experiments on the role of conscious will in voluntary action appear to show that consciousness comes too late to initiate voluntary actions, so threatening free will. We review the long-lasting debates about the methodology and implications of Libet’s findings. Recent fMRI experiments  have been able to predict people’s decisions from their brain activity several seconds in advance. Research on the experience of willing reveals a double dissociation between believing you have caused certain actions and the actual cause of those actions, implying that the feeling of acting freely provides no evidence either way. The final section considers the moral and ethical consequences of belief, and of giving up belief, for both individuals and wider society.

Suggested films:

Minority report, dir. Steven Spielberg (2002): based on a story by Philip K. Dick, this film is about a man on the run for a murder a psychic has foreseen he will commit; can he choose to do otherwise? (After watching you could take a look at the discussion here)

Groundhog day, dir. Harold Ramis (1993): a man has to relive the same day over and over, yet retains the ability to exercise free will and make each iteration turn out differently (try this analysis after watching)

Suggested literature:

The outsider / The stranger (L’Étranger), Albert Camus (1942) (in the translation by Matthew Ward): a man does not weep at his mother’s death; soon afterwards he commits an unpremeditated murder, and is tried and sentenced to death

Crime and punishment (Prestuplenie i nakazanie), Fyodor Dostoevsky (1866) (translated by Richard Pevear and Larissa Volokhonsky or Oliver Ready): a former student murders a pawnbroker for her money, and creates a philosophical defence of his actions; his story is full of questions about coincidence, gaps in consciousness, and the mechanical lack of any sense of choosing to do things


Determinism vs free will: Crash course philosophy #24 (CrashCourse) (10:25): outlines some of the ways libertarians try to avoid hard determinism, and how determinism relates to reductionism and predictability when it comes to, say, choosing what to have for breakfast

Roy Baumeister – Free will and decision making (Closer To Truth) (6:59): defends the notion of freedom

Daniel Dennett – What is free will? (Closer To Truth) (6:00): Dennett’s attempt to preserve freedom for our willing

Neuroscience and free will – Libet’s experiment (luoshuzai) (3:36): Susan Greenfield is the participant in Patrick Haggard’s recreation of the Libet experiment

Thalia Wheatley is free will an illusion (Galen Orwell) (8:43): includes descriptions of her experiments with Dan Wegner

Sam Harris free will thought experiment (Cogent Canine) (6:36): a free-will task to try for yourself

Sam Harris on free will (Joe Rogan experience #543) (David McGinn) (55:43): includes discussion of the legal implications of the nonexistence of free will, and Rogan’s resistance

Living without free will, Susan Blackmore (scienceandnonduality) (1:11:21): could conscious thoughts ever cause actions, and what do we do about it if they can’t?


Daniel Wegner on the information philosopher: excerpts from The illusion of conscious will (2002)

The big questions: Do we have free will? (New Scientist): Patricia Churchland answers the question by focusing on the neurobiology of self-control

Chapter 10: Evolution and animal minds

Chapter Summary

The basic principles by which evolution creates design without a plan or designer are outlined. Darwin’s idea of ‘descent with modification’ is explained in terms of the evolutionary algorithm and the ‘modern synthesis’ between genetics and evolutionary theory. Selfish gene theory suggests the possibility of a second replicator, the meme, which depends on human imitation. What about other animals? Can we ever know whether octopuses, rats, or crows, with their very different experienced worlds, are conscious? Can we tell whether they feel pain or suffer? We might consider physical criteria like brain size, function, and organisation; or behavioural criteria like intelligence, memory, or insight. But should we compare vastly different species against our own abilities? Mirror self-recognition has been widely used to test whether animals have a sense of self, but this method has its problems. Other research has investigated animals’ ‘theory of mind’ or ability to understand others’ beliefs and intentions, and their capacity for imitation. Arguably the greatest divide between us and other species is language, and attempts to teach language to other species are reviewed. We are left wondering whether an octopus is conscious and whether this question even makes sense.

Suggested film:

White god, Kornél Mundruczó (2015): the daughter of a slaughterhouse inspector loves a street dog whom a neighbour reports to the authorities; much of his subsequent unhappy life without her, and his final revenge against humankind, is told from the dog’s perspective

Suggested literature:

Black Beauty, Anna Sewell (1877): a horse describes his life

Jennie, Paul Gallico (1950): a boy is knocked down by a car and when he comes to, finds he is a cat, not a human any more; an abandoned cat teaches him how to survive

Never cry wolf, Farley Mowat (1963): the autobiographical account of how a young boy discovers a love of animals, and ends up overthrowing everything he thought he knew about wolves

My family and other animals, Gerald Durrell (1956): a tale of the five years Durrell and his family spent living amidst the wildlife of Corfu


Natural selection – Crash course biology #14 (CrashCourse) (12:43): how Darwin’s insights arose

Richard Dawkins – The selfish gene explained (The Royal Institution) (4:12): the immortality of genes and bodies as throwaway survival machines for the coded information they contain

Group selection and multi-level selection (Mind.Blown) (5:39): how the group level can trump the individual level, for chickens and religions

Why the octopus brain is so extraordinary – Cláudio L. Guerra (TED-Ed) (4:16): on the profound differences between human and octopus physiology and ways of life

What is panpsychism? (philosophical definitions) ( (15:04): related positions, and arguments for and against

What are animals thinking and feeling? | Carl Safina (TED) (19:26): what kinds of questions should we really be asking?

Do crabs feel pain? (Seeker) (3:34): brief round-up of evidence suggesting they do

Crafty crayfish removes own claw to escape China hotpot (originally from Jiuke, on Weibo) (0:11): see also the interesting range of Reddit users’ responses, and a BBC report here

Is elephant self aware and conscious? (Hossein Akhlaghpour) (3:22): different phases of interaction with mirrors, illustrated through elephants

Self recognition and the rise of what most refer to as personhood (J. Patrick Malone) (4:24): footage of chimps encountering new objects, and one female apparently coming to recognise herself in a mirror

Humans aren’t the only great apes that can ‘read minds’ (Science Magazine) (3:37): one experimental paradigm for testing chimps’ ability to track false beliefs in humans

Crows, smarter than you think | John Marzluff | TEDxRainier (TEDx Talks) (22:13): the case for corvid intelligence – and consciousness

Amazing parrot imitating many sounds (filrich1) (3:03): Einstein the African grey parrot wows a game-show audience

Inside the minds of animals – Bryan B Rasmussen (TED-Ed) (5:12): a brief history of human thought about other animals’ cognition and consciousness

Animals in translation – How animals think and feel (Smithsonian Education) (1:27:19; presentation ends 47:30): Temple Grandin covers a wide range of examples of how to interact effectively with other animals

Jane Goodall on animal consciousness and the realities of the ivory trade (Strombo) (2:02): a brief clip to demonstrate chimp consciousness

What is so special about the human brain? | Suzana Herculano-Houzel (TED) (13:31): how our brains compare to other species’, emphasising the importance of the number of neurons in the cerebral cortex

Sam Harris & Joe Rogan talk consciousness & pain in animals etc. (setsuko crisman) (39:26): discussion of the anthropomorphic basis of attributing the capacity for pain and suffering to different species, and of whether conscious life has any value in itself

Is the human mind unique? – Daniel Povinelli: Desperately seeking explanation (University of California TV) (20:12): how explanatory capacities distinguish us from apes, and how the strength of our explanatory mania has its dangers as well as its benefits

What is it like to be a baby: The development of thought (YaleCourses) (48:57): overview of research on how infants’ thinking about the physical and social world develops

Dylan (Baba Brinkman Music Video) (4:29): a father raps about whether his son is conscious (view the full album, The Rap Guide to Consciousness, here)

Chapter 11: The function of consciousness

Chapter Summary

Does the fact that we are conscious mean that consciousness must have evolved to serve a function? Not necessarily. This question relates to whether consciousness has causal efficacy and whether we humans might have evolved as zombies rather than ‘conscies’. Four ways of thinking about the evolution of consciousness are explored: 1) Belief in zombies, or ‘conscious inessentialism’, leads to an impasse. 2) If consciousness has an adaptive function in its own right (whether individual or social), we can ask when consciousness evolved, but there is no consensus, with answers ranging from billions of years ago to just a few thousand. 3. Consciousness may have no independent function, but be an inevitable concomitant of other evolved capacities. Theories of this type include eliminative materialism and some forms of functionalism, theories concerning communication and language, and predictive-processing theories. 4) Consciousness is an illusion and we should instead ask: ‘how did the illusion of consciousness evolve?’ Illusionist theories draw on language, thought, and our ability to control attention and monitor our internal states. Finally, there may be evolutionary processes operating within individual brains or between people in cultures, and consciousness may itself be a complex of memes.

Suggested film:

Blade runner, dir. Ridley Scott (1982), and Blade runner 2049, dir. Denis Villeneuve: in a dystopian universe based loosely on Philip K. Dick’s novel Do Androids Dream of Electric Sheep?, replicants serve as slave-labour for humans, and have to be rigorously policed to make sure they don’t have thoughts and desires inconsistent with their functional purpose (see Rutger Hauer’s famous ‘Tears in rain’ speech from the first film, on the tragedy of having a consciousness at odds with one’s purpose)

Suggested literature:

Blindsight, Peter Watts (2006): a spaceship with a transhuman crew captained by an artificial intelligence discovers a vessel that harbours organisms with intelligence but apparently without consciousness


Human behavioral biology, evolutionary psychology, 2: Behavioral evolution – Robert Sapolsky, Stanford University (Stanford) (1:36:56): covers questions relating to morality and game theory, including The Prisoner’s Dilemma; the rest of the wide-ranging series is also recommended

Selfish genes, selfless vehicles, kin selection & reciprocal altruism (TubeCactus) (2:58): a quick run-through from Dawkins

Julian Jaynes and the bicameral mind theory (This View of Life Magazine) (20:55): brief summary and discussion of Jaynes’s ideas

How human consciousness evolved | Daniel Dennett (Big Think) (6:45): the crucial role of language in driving cultural evolution, and why comprehension and consciousness follow from competence, not the other way round

Susan Blackmore – Memetic evolution (bilkable) (6:12): the memetic perspective on the development of human culture and intelligence

Memes saved from extinction, Dan Dennett (Santa Fe Institute) (46:56): on the gradual de-Darwinisation of culture, as memetic selection began to outstrip the genetic, with memes as ways of doing things – an essential concept for understanding cultural evolution

Richard Dawkins | Memes | Oxford Union (OxfordUnion) (9:41) and Richard Dawkins | Religion as a computer virus | Oxford Union (OxfordUnion) (6:15): extracts from a Q&A at the Oxford Union

Susan Blackmore, Robert Wright and Richard Dawkins: Memes podcast (bilkable) (46:56): conversation on the basics of memetics

The magic of consciousness (The Royal Institution) (7:32): Nicholas Humphrey asks why the illusion of consciousness should ever have evolved; see also the follow-up Q&A video here


A self worth having: Nicholas Humphrey discusses the function of consciousness, his involvement in the discovery of blindsight, what he learned from Dian Fossey and wild gorillas, and how to make a difference as a scientist; with responses from Prinz, Noë, Sheldrake, Dennett, Metzinger, and others

The third replicator: Susan Blackmore on Earth’s ‘Pandoran species’ and where we’re headed now a third replicator is piggybacking on the second one. This is The New York Times’s republication (in 2010) of an original New Scientist article (2009), here.

See also the numerous comments, plus Sue’s response to them, here, as well as a call for the right name for the third replicator (teme, treme…?), here. This may make for good material for group discussion.

Chapter 12: The evolution of machines

Chapter Summary

Could machines ever be conscious? Ways to find out include reverse-engineering human machines or artificial ones. A brief history of artificial intelligence (AI) leads from early automata through calculating machines and ‘Good Old-Fashioned AI’ to connectionism, embodied cognition, and swarm robotics. Turing asked ‘Can machines think?’ Attempts to pass his famous test are reviewed, including chess-playing machines and programs that can converse with humans. Strong AI posits that machines can really think while weak AI claims that they can only simulate thinking. A similar distinction applies to consciousness (strong AC versus weak AC), but how can we test whether a machine is really conscious? Some dualist and religious arguments claim that only biological systems can be conscious. Searle’s ‘Chinese Room’ thought experiment purports to refute strong AI; its many criticisms and variants are reviewed. Others argue that conscious machines are perfectly possible and may already exist. Among strategies discussed are building machines that model attention, self, and the external world; machines with global workspace architecture; and social robots which people react to as though they are conscious. A final approach is to build a machine that believes it is conscious even though this is an illusion.

Suggested film:

Her, dir. Spike Jonze (2013): a man falls in love with his computer

Suggested literature:

Frankenstein, Mary Shelley (1818): a student discovers how to give life to an inanimate body, but is afraid of his own creation


Turing machines explained (Computerphile) (5:24): the computational basics

On the Turing completeness of Microsoft PowerPoint (Tom Wildenhain) (5:33): can we use PowerPoint to do everything? PPT as Turing machine

Artificial intelligence & personhood: Crash course philosophy #23 (CrashCourse) (9:25): includes the weak/strong AI distinction, and ways of trying to define the strong version: the Turing Test and the Chinese Room

Room (Baba Brinkman Music Video) (1:53): an old man passes himself off as a rapper (view the full album, The Rap Guide to Consciousness, here)

Andy Clark and Barbara Webb: Embodied cognition and the sciences of the mind (Wk8 pt1) (Philosophy at the University of Edinburgh) (8:59; plus 15:15 for Part II): embodiment in natural and artificial machines: how, as opposed to the ‘naked brain’ hypothesis, physical structures help solve problems; Part II progresses on to more complex tasks and interactions

Rodney Brooks and bottom-up robots (Deedlydeedee) (7:24): an ’80s film on taking inspiration from the insect world to initiate stimulus-response-based robotics

Rodney Brooks – How do brains work? (Closer To Truth) (10:36): the different things humans, other animals, and robots find difficult, and what robotics reveals about human minds

How the most human human passed the Turing test (Quartz) (4:50): how to prepare to compete against the AI programs, and why we’re making it ever easier for them to pass the test

Christof Koch – Can consciousness be non-biological? (Closer To Truth) (6:07): there’s no reason to think otherwise, and maybe the internet is already conscious

The consciousness debate – Part 1: Christof Koch (The Guardian) (11:05): on consciousness in brains and machines, including IIT

Consciousness in biological and artificial brains (Allen Institute for Artificial Intelligence) (1:03:38): a fuller exploration of how IIT relates to artificial consciousness, diverging from his earlier ideas by suggesting, for example, that IIT predicts that feedforward neural networks and digital computers would not be conscious

AI vs. human: The greatest Go tournament ever (SciShow) (4:06): why AlphaGo’s victory matters

ECCEROBOT – Embodied cognition in a compliantly engineered robot (eccerobot) (2:04): brief footage of the design characteristics

Luc Steels: Can robots invent their own language? (SoftBank Robotics Europe) (33:53): exploring how language and the concepts it expresses can be grounded in the sensorimotor features and interactions of humans or robots

Making an ethical machine | Alan Winfield (World Economic Forum) (5:20): ethics can be programmed into robots merely via the ability to model and predict consequences of one’s own and others’ actions; see also a fuller exploration of related ideas here

Susan Blackmore: Memes and temes (TED) (21:00): on the emergence of a new third replicator (after genes and memes) which is spread via technology, setting loose a new evolutionary process (Sue later switched the term from teme to treme; see more on tremes here)

The evolution of virtual pets (EDWON) (5:49): from Tamagotchi to the VR future

Dr. Cynthia Breazeal – Part 1 – The personal side of robots (SFIDiscover) (31:11): the first of a four-part video on why personal robotics is the real challenge and excitement


Flowers can hear buzzing bees – and it makes their nectar sweeter: Michelle Z. Donahue, writing for National Geographic, presents the latest evidence that plants can hear.

Artificial intelligence – the revolution hasn’t happened yet (Michael Jordan): the importance of distinguishing between ML (machine learning), AI (human-imitative artificial intelligence), IA (intelligence augmentation), and II (intelligent infrastructure) in solving the human-centric technological challenges of the future

Is AlphaGo really such a big deal? (Michael Nielsen): tl;dr: yes

Postmodernism generator: uses recursive grammars to randomly generate postmodern essays

Will a machine ever be conscious? (and other cartoons) (Riccardo Manzotti)

Psychoprosthetics: Can a prosthesis ever really become a part of you? (All in the Mind, ABC): transcript of a radio programme in which people who have lost limbs talk about their experiences of the loss, and of their new replacements

The singularity, virtual immortality and the trouble with consciousness (OpEd), Robert Lawrence Kuhn: the causes of consciousness and what will happen if we try to replicate our conscious selves – including quotes from some of the many thinkers interviewed in his Closer To Truth videos)

For the Turing test Activity:

You can find poetry examples (and data on how many people voted the poems ‘Bot’ or ‘Not’) here (see under ‘Free play’ and ‘Take the DWF quiz’)

Or there are jokes here, courtesy of The Joking Computer: you can use the software to generate new jokes, or use some of the Computer’s better efforts

There are six sonnets submitted to a Turing-test competition here

You can read about Zachary Scholl’s (or his poetry generator’s) triumph here (with a link to Scholl’s blog and from there to the generator source code)

Can a computer write poetry? | Oscar Schwartz (TED) (10:56): on the unsettling proof that Gertrude Stein is a computer

Some extra detail on noncomputability courtesy of a friendly mathematician, James Anderson (Caltech)

Q: Can you give us some simple examples of non-computable problems?

Answer: The problem is that most non-computable problems are very easy to state but are quite abstract. Typically, in algebra at school you are taught that a function takes some numbers as inputs and spits out a number as an output. For example, the square root function takes a (non-negative) number, x, as its input and returns a non-negative number as its output: f(x) = sqrt(x) e.g. for x = 9, f(x) = f(9) = 3. Similarly, the function ‘add 1’ (call this function g) takes any value x and returns x+1: g(x) = x+1, e.g. x = -4 then g(x) = -3. Some functions take multiple arguments, e.g. the function ‘addition’. Call the addition function h. Then h(x,y) returns x+y. so for x = 1, y = 4, h(x,y) = 5.

But functions can take much more complicated things as inputs. It could take in a set of instructions to cook something. Call it a recipe. The function may then be: take recipe as the input, and produce an output of ‘1’ if the recipe bakes a cake, else output ‘0’. In this case the input x is a recipe, and the function, f, takes this and tells you if you have a cake. For example, let the input be:

x = [1: break egg, 2: put in frying pan, 3: fry egg for 2 mins]

Then f(x) = 0 because this isn’t a cake, it’s a fried egg (at least according to any reasonable definition of a cake).

So if you think of functions taking inputs that are algorithms (or recipes), and the function’s output is a decision as to whether the input (the algorithm) has a certain behavior, then you can construct functions that are not computable. One of the most common non-computable functions is the function that takes as an input a description of a computer program and an input to that program. The output of the program is ‘1’ if the program terminates in finite time, and ‘0’ if it runs forever. So in this case the function, f, looks like this:

x = [description of algorithm]

y = [input to algorithm]

f(x,y) = 1 if given x and y the program terminates in finite time. ‘0’ otherwise.

Such a problem is called a decidability problem. The most famous decidability problem is ‘the halting problem’, which Turing proved was uncomputable, therefore the above function is trying to decide something undecidable, which it can’t possibly do – and so it is by definition uncomputable. A really nice cartoon that explains (and actually proves) this is here. Any problem that is Turing undecidable, when put in the form above, is non-computable.

A more ‘concrete’ example of the above is:

Given a polynomial function: e.g. p(x) = ax^2 +bx^3, where a and b are known integers i.e. 1,2,3,4, etc. Let the function, f, take p as its input and output ‘1’ if the solution to p(x) has an integer solution, i.e. solve ax^2+bx^3 = 0 for x. We did this in school for quadratic functions (but it is really difficult for powers of 3 and higher). If x is an integer then our function f returns ‘1’, else it returns ‘0’. This is known to be undecidable and therefore the f is not-computable.

Q: Kurzweil (1999) rejects Penrose’s theory, saying ‘It is true that machines can’t solve Gödelian impossible problems. But humans can’t solve them either.’ Is this true? Can you first explain what a Gödelian problem is?

Answer: Gödel’s first incompleteness theorem says (from Wikipedia): ‘Any consistent formal system F within which a certain amount of elementary arithmetic can be carried out is incomplete; i.e., there are statements of the language of F which can neither be proved nor disproved in F.’

Breaking this down . . .

  • A formal system basically means a system based on mathematics.
  • Consistent means what you think it does. Given the axioms of a system you cannot prove that a single statement is both simultaneously true and false using said axioms.
  • A sentence which can neither be proved or disproved is called the Gödel sentence. And here comes the crazy bit: The Gödel sentence is usually a sentence stating that ‘there exists a sentence that can neither be proved or disproved’.

The point is that in order to prove or disprove certain statements in F, you would need to use logic/rules/etc. that come from outside the system. One of the main misunderstandings of Gödel’s theorem is to assume that the theorem asserts that there are things that cannot be proved. This is incorrect: the theorem tells us that something cannot be proved in the formal system F; it doesn’t say anything about what can or can’t be proven in other systems.

Q: Are these impossible problems one class of the non-computables above?

Answer: I think this question is either not well-posed or trivial and I can’t decide which! Both noncomputability and Gödelian theorems deal with very similar ideas, but one uses Turing machines as the work horse while the other uses set theory. A slightly weaker version of the Gödel’s first incompleteness theorem can actually be derived from the halting theorem. The details aren’t important here, but the idea is that the axiomatization of F can be encoded by a Turing machine. When this can’t be done you get an ill-posed problem where you are comparing two similar but different objects. When this encoding does exist then the impossible problems are examples of provably non-computable problems.

The problem with these arguments is that they are *very* subtle. I’m not clear on a lot of the details of some definitions so trying to manipulate them to form some sort of statement is risky!

Q: And is it plausible to claim, with Penrose, that the brain could do some of the things that are non-computable for machines?

Answer: Really tough question. You could argue that humans make mistakes and so are not consistent and therefore Gödel’s theorems don’t apply to humans (Putnam’s argument). ‘Is the brain a computer?’ seems to get reduced to: ‘if the brain is a computer it can be described by a Turing machine’. If this is true and the TM is consistent, then Gödel’s results apply to it and there are things we cannot compute/decide. I think Penrose’s argument is something like: A true intelligence cannot be algorithmic and deterministic, or, put another way, susceptible to Gödel’s incompleteness theorem.

I have no idea whether I think the brain is a computer or not! A lot of it comes down to the question, ‘what is a computer?’ It seems that very smart people argue that it is and it isn’t! If I had to hedge I’d say yes, the brain can do things a computer/machine finds non-computable because the definition of non-computable places a lot of restriction on what sort of computations are allowed.

Additional material from the 2nd edition:

Try the classic imitation game instead of or as well as the Turing test for creativity.

Activity – The imitation game

Without a brilliant machine at your disposal you cannot try out the Turing test, but you can play Turing’s original ‘imitation game’ (Turing, 1950), which is fun to do and works well as a demonstration of what the Turing test involves. The main skill for the judges consists of working out what sort of questions to ask – a similar challenge whether the contestants are both people, or a person and a machine.

The organiser must choose a man and a woman to act as contestants. Ideally, they should not be known to the class. If this is impossible, at least avoid people who are very well known to everyone. The contestants go into a separate room, or behind a solid opaque screen, where they are secretly labelled X and Y. The rest of the class act as judges and have to ask questions. Their task is to determine which is the woman.

The real woman has to help the judges, while the man pretends to be a woman.

Low-tech version. The judges write questions on pieces of paper. They may address their questions to X, Y, or both. The organiser selects a question and takes it into the next room, gets the answer, and then reads it out to the class. For example, the question might be ‘To X and Y, how long is your hair?’. The organiser gets both X and Y to write answers and reads out ‘X says “my hair is shoulder-length”; Y says “I have long brown hair”’. Obviously, the man may lie; if he is asked ‘Are you a man?’ he will say ‘no’, and if asked ‘What is your ideal partner like?’ or ‘Are you good at reading maps?’ he will have to answer as he thinks a woman would. When enough questions have been answered the organiser asks everyone to say whether X or Y was the woman. X and Y then come out and show their labels.

One problem is that the organiser may unwittingly give away clues about which person is which. Even so, this version works well, even if done with only a screen in the corner of the room. However, if you want a tighter method, and are willing to prepare in advance, try this:

High-tech version. Provide each contestant with a computer and a projector that makes their typed answers visible to the class. The contestants can be hidden, either in another room or behind a screen. It is important that however the answers are projected, they are clearly labelled X and Y. The organiser collects the written questions as before and the contestants type their answers on their computer. At a pinch, one computer can be used and the contestants can take it in turns, but this is slower and can lead to confusion if not well organised. The game can also be played online, for example here.

The imitation game provides an ideal introduction to discussing the most important aspect of the Turing test: what questions should you ask the machine, and why?


Turing, A. (1950). Computing machinery and intelligence. Mind, 59, 433–460.

Chapter 13: Altered states of consciousness

Chapter Summary

Altered states of consciousness (ASCs) are surprisingly hard to define or measure. Neither subjective methods, like verbal reports, nor objective measures such as how the state is induced, or physiological and behavioural criteria, are entirely satisfactory. Attempts to map ASCs are reviewed, including two- or three-dimensional maps such as Tart’s and Laureys’, and Hobson’s AIM model, but the true space of possibilities is likely to be vast. Psychoactive drugs include stimulants (amphetamine, MDMA), anaesthetics (nitrous oxide, ketamine), cannabis, and major psychedelics (mescaline, psilocybin, DMT, ayahuasca, LSD). Experiments using these drugs were long prohibited, but brain scans are beginning to reveal changes to attention systems and the default mode network, and clinical studies show promise in alleviating depression and anxiety, especially for the terminally ill. Meditation can also lead to ASCs: for example, the ‘jhanas’ are eight discrete states induced by deep concentrative meditation. Consideration of altered states in mental illness, such as anorexia or depression, raises further problems in deciding what counts as an altered state and what to compare it with. Is there a ‘normal’ or baseline state for comparison? Many of this chapter’s questions apply also to hypnosis, and we briefly review the ongoing state/non-state debate.

Suggested films:

Enter the void, dir. Gaspar Noé (2010): a terrifying amalgam of drugs, sex, death, and out-of-body psychedelia in nighttime Tokyo

Requiem for a dream, dir. Darren Aronofsky (2000): a bleak insight into the everyday of drug addiction

A scanner darkly, dir. Richard Linklater (2006): based on Philip K. Dick’s novel of the same name about a world dominated by the highly addictive narcotic Substance D, in which the protagonist spirals towards self-alienation and the limits of consciousness and the audience loses track of the boundaries of reality

Field of dreams, dir. Phil Alden Robinson (1989): hallucinatory experiences (first private auditory experiences, progressing to visual experiences which are later also shared with others) make a novice farmer risk everything to turn part of his cornfield into a baseball field

Suggested literature:

The doors of perception, Aldous Huxley (1954): an account of the eight-hour experience of taking mescaline, one day in May 1953

Confessions of an English opium-eater: Being an extract from the life of a scholar, Thomas De Quincey (1821/1886): how De Quincey’s laudanum (a combination of opium and alcohol) addiction changed his life (including ‘Preliminary confessions’, ‘Pleasures’, and ‘Pains’)

Journey into the bright world, Marcia Moore and Howard Sunny Altounian (1978): detailed descriptions of the dissociative experiences induced by ketamine, and their therapeutic and mind-expanding value, including transcriptions of the tapes Altounian made during his ketamine experiences with his wife, Moore. Ketamine may have contributed to her death the year after publication (see here and here for brief accounts).

PiHKAL [Phenethylamines I have known and loved]: A chemical love story, Alexander and Ann Shulgin (1991). Part 1 is a fictionalised autobiography of the authors; Part 2 (here) contains detailed synthesis accounts, bio-assays, dosage information, descriptive accounts of the drugs’ controlled consumption, and other commentary

Glow, Ned Beauman (2014): a young man with a strange sleep disorder hears about the latest recreational drug, glow

Fear and loathing in Las Vegas, Hunter S. Thompson (1971): a stream-of-altered-consciousness account of a trip to Vegas in a car full of drugs

The bell jar, Sylvia Plath (1963): a woman’s mental illness, attempted suicide, and partial recovery


Altered states – Crash course psychology #10 (CrashCourse) (11:18): includes hypnosis, drugs, and hallucinations

Charles Tart – What are altered states of consciousness? (Closer To Truth) (12:12): the spectrum from endarkenment to enlightenment

Intoxication and consciousness (Sunshine Coast Health Centre) (3:47): why consciousness matters in understanding addiction

Psychedelics: Effects on the human brain and physiology | Simeon Keremedchiev | TEDxVarna (TEDxTalks) (26:55): covers physiological and experiential effects and legal implications

Neural correlates of altered consciousness: Hypnosis, meditation, & drug-based changes – Amir Raz (MAPS) (36:38): includes reflections on what it means to be a scientist of experience

Drunk squirrel (Shadi Petosky, 2:07): what are altered states like for nonhuman creatures?


Nick Sand | Moving into the sacred world of DMT (radiOzora) (58:47): underground chemist Nick Sand talks about his lifetime of creating and exploring many psychedelics, and doing time in prison


Going loopy (Slate Star Codex): mental health, feedback loops, antidepressants, and LSD

Additional material from 2nd edition:

Here are some additional details on the main classes of drugs and their effects.

Concept – Drug groups and effects

The main categories of psychoactive drugs are as follows:

Stimulants.  Central nervous system (CNS) stimulants include nicotine, caffeine, cocaine, and the large group based on amphetamine.

Cocaine is a dopamine reuptake inhibitor derived from the South American shrub Erythroxylon coca, whose leaves are chewed to reduce exhaustion and hunger. It induces intense pleasure, energy, and confidence and is a common street drug, either inhaled into the nose as a powder or converted to free base form and smoked as crack cocaine, a particularly fast-acting and extremely addictive form. The euphoric effects are caused by increased dopamine acting on the midbrain reward system. Cocaine induces tolerance and has unpleasant withdrawal symptoms. Heavy users experience hallucinations, including formication, the very odd and highly specific hallucination of bugs crawling under the skin.

Amphetamine, or speed, is another dopamine reuptake inhibitor, and has similar energising effects. Tolerance develops with repeated use, and withdrawal causes depression and lethargy. Long-term heavy use can lead to paranoid delusions and hallucinations. Among designer drugs derived from amphetamine is 3,4-methylenedioxy methamphetamine, MDMA, or ecstasy. This inhibits serotonin reuptake and increases release of both serotonin and dopamine. Repeated use can lead to tolerance and addiction and it may have long-term effects on the serotonin system.

CNS depressants. These include alcohol, which also has stimulating effects before CNS depression sets in, as well as some inhalants, barbiturates, and minor tranquillisers. They have different modes of action, including facilitation of GABA, effects on endogenous opioids, and inhibition of adrenaline and acetylcholine.

Narcotics.  These include heroin, morphine, codeine, and methadone, all of which have powerful effects on mood and are highly addictive. They mimic the effects of endogenous opioids. Opium produces varied effects, described in the autobiography of the English essayist and critic Thomas De Quincey (1821) as inducing visions of the utmost beauty and as the key to paradise, until he suffered nightmares and addiction.

Antipsychotics.  Major tranquillisers include lithium carbonate and chlorpromazine and are used primarily in the treatment of schizophrenia.

Antidepressants.  The three major types are tricyclic antidepressants (TCAs); selective serotonin reuptake inhibitors (SSRIs), which increase the availability of serotonin by slowing its removal from the synapse; and monoamine oxidase inhibitors (MAOIs), which slow the breakdown of noradrenaline, dopamine, and serotonin.

Anaesthetics.  Designed to induce unconsciousness and insensitivity to pain for medical use, there are many types, including those usually injected, such as propofol, barbiturates, benzodiazepines, and ketamine, and gases such as ether and nitrous oxide. They have a variety of effects on GABA, serotonin, glutamate, and other receptor systems.

Psychedelics.  The major psychedelics include DMT (dimethyltryptamine, an ingredient of ayahuasca), psilocybin (found in ‘magic mushrooms’), mescaline (derived from the peyote cactus), many synthetic drugs including LSD (lysergic acid diethylamide), numerous phenethylamines (Shulgin and Shulgin, 1991), and many drugs in the tryptamine series with varying effects and time courses (Shulgin and Shulgin, 1997). There are also synthetic forms of mescaline and psilocybin. Most structurally resemble neurotransmitters, including acetylcholine, noradrenaline (norepinephrine), dopamine, and serotonin (Julien, 2001). Mescaline resembles noradrenaline (norepinephrine) and many others mimic the effects of serotonin. Most can be toxic at high doses, although LSD is said to have no known lethal dose. They are not generally addictive.

Cannabis is sometimes classified as a minor psychedelic. Its main active ingredient is delta-9-tetrahydrocannabinol, and this, together with cannabinol and cannabidiol, produces psychoactive effects by acting on the cannabinoid receptors. Endogenous cannabinoids are thought to facilitate memory extinction in the hippocampus, which might explain cannabis’s effects on memory. However, there are over sixty other cannabinoids unique to the plant, all of which have slightly different effects on the brain and the immune system, and hundreds more chemical constituents that may all affect each other and change the effect of the final mixture (Farthing, 1992; Julien, 2001; Earleywine, 2002).

The effects of all drugs depend both on dose and method of ingestion. Drugs taken orally work much more slowly than those injected, smoked, or inhaled. Natural mixtures can have far more subtle and interesting effects than isolated ingredients or synthetic versions.


De Quincey, T. (1821/1886). Confessions of an English opium-eater: Being an extract from the life of a scholar. New York: George Routledge and Sons. Full text here.

Earleywine, M. (2002). Understanding marijuana: A new look at the scientific evidence. New York: Oxford University Press.

Farthing, G. W. (1992). The psychology of consciousness. Englewood Cliffs, NJ: Prentice Hall.

Julien, R. M. (2001). A primer of drug action: A concise, nontechnical guide to the actions, uses, and side effects of psychoactive drugs.Rev. ed. New York: Henry Holt.

Shulgin, A., and Shulgin, A. (1991). PiHKAL (Phenethylamines I Have Known and Loved). Berkeley, CA: Transform Press.

Shulgin, A., and Shulgin, A. (1997). TiHKAL (Tryptamines I Have Known and Loved). Berkeley, CA: Transform Press.

Read this section if you are interested in Pahnke’s Good Friday experiment and the relation between drug-induced altered states and mystical experiences.

Exceptional human experiences

I remember the night, and almost the very spot on the hill-top, where my soul opened out, as it were, into the Infinite, and there was a rushing together of the two worlds, the inner and the outer. It was deep calling unto deep, –– the deep that my own struggle had opened up within being answered by the unfathomable deep without, reaching beyond the stars. I stood alone with Him who had made me, and all the beauty of the world, and love, and sorrow, and even temptation. . . . nothing but an ineffable joy and exaltation remained. (James, 1902, p. 66)

This religious experience, recounted by a clergyman and included in William James’s classic The Varieties of Religious Experience, profoundly affected the man’s life. Like many others who have experiences of this kind, he described it as ineffable, or impossible to put into words: ‘I feel that in writing of it I have overlaid it with words rather than put it clearly.’

Today his might be labelled an ‘exceptional human experience’ (EHE): a broad category encompassing psychic visions, hypnotic regression, lucid dreams, peak experiences, and religious and mystical experiences. The term was coined by American parapsychologist Rhea White (1990) to describe experiences that entail a shift away from the usual feeling of self as something inside the skin and towards a greater sense of self. Thus, EHEs are not merely odd or inexplicable experiences, but self-transformative ones.

Some of these experiences prompt paranormal or supernatural claims. Others are taken as evidence for God, souls or spirits, or life after death. So they raise many questions. Are any of these claims valid? Is there a common theme running through the experiences or are they just a loose collection of unrelated oddities? And what can they tell us about the nature of self and consciousness? Responses to these questions may be divided into three rough groups.

First, the dismissive response treats all EHEs as inventions or lies, as uninteresting by-products of brain states, or as pathological conditions that need treatment.

Second, the supernatural response takes EHEs as evidence that materialist science is wrong and must be expanded to include the paranormal, God, the soul, or the power of consciousness to reach beyond the body. Paranormal events are often seized upon to confirm the validity of the experiences. Although an understandable reaction against the dismissers, this may detract from understanding the deeper core of some experiences.

Third, the naturalistic response treats EHEs as worthy of investigation in their own right, but as normal rather than paranormal. It seeks to understand them without recourse to gods, spirits, or psychic powers.

In this book we consider various kinds of EHE, such as dissociative states (Chapter 16) and putatively extra-sensory experiences or experiences of other worlds (Chapter 14).

Mystical experiences

All at once, without warning of any kind, I found myself wrapped in a flame-colored cloud. For an instant I thought of fire, an immense conflagration somewhere close by in that great city; the next, I knew that the fire was within myself. Directly afterwards there came upon me a sense of exultation, of immense joyousness accompanied or immediately followed by an intellectual illumination impossible to describe. Among other things, I did not merely come to believe, but I saw that the universe is not composed of dead matter, but is, on the contrary, a living Presence; I became conscious in myself of eternal life. It was not a conviction that I would have eternal life, but a consciousness that I possessed eternal life then . . . That view, that conviction, I may say that consciousness, has never, even during periods of the deepest depression, been lost. (James, 1902, p. 399)

This is how Canadian psychiatrist Richard Maurice Bucke described what happened one night in a hansom cab on his way home from an evening spent with friends reading the poetry of Shelley, Keats, and Whitman. He proceeded to study similar experiences in history and literature, and coined the term ‘cosmic consciousness’ to describe them. This he described as a third form of consciousness: as far above human self-consciousness as that is above the simple consciousness that we share with other animals. Its prime characteristic is ‘a consciousness of the cosmos, that is, of the life and order of the universe’ (Bucke, 1901, p. 3), along with an intellectual and moral elevation, and a sense of immortality in the present moment.

Such experiences are usually called ‘religious experiences’ or ‘God experiences’ if they involve religious symbolism or a deity (Persinger, 1999). They are surprisingly common. Thousands of cases, mostly of Christian influence, were collected by the Religious Experiences Research Unit, founded by Oxford biologist Sir Alister Hardy in 1969 (Hardy 1979). The term ‘mystical experience’ is rather broader, and is probably impossible to define in a way that does the experiences justice. Perhaps the best we can do, as many authors have, is to list their common features.

James (1902) proposed four marks that justify calling an experience ‘mystical’.

The first is ineffability. That is, the experience somehow defies description in words. People feel that anything they say is misleading and the experience cannot be imparted to others. A mystical experience cannot, therefore, be a meme, unlike the term ‘mystical experience’, which is a meme.

The second is ‘noetic’ quality, a term that James coined (from the Greek root noeîn, to intend,to perceive, to understand) to describe the sense that mystical states are states of knowledge, insight, or illumination. They carry a curious, and lasting, sense of authority.

Third is transiency. They rarely last more than half an hour or an hour before fading to a kind of after-glow. After this they cannot be clearly remembered but are easily recognised when they recur, allowing for continuous personal development.

Fourth is passivity. Although circumstances can be arranged, and habits adopted, to make mystical experiences more likely, they cannot be induced to order and once they begin the mystic feels as though his or her own will is in abeyance.

Many other writers have made different lists but nearly all include these four qualities. Many, such as the philosopher Walter Stace (1960), stress the sense of unity, or the loss of self in the One. Others add the loss of time and space to the loss of self. D. T. Suzuki, who is credited with bringing Zen to the West, adds a sense of the beyond, an impersonal tone (which is emphasised more often in Zen satori experiences than in Christian mysticism), a feeling of exaltation, and affirmation, by which he means an accepting attitude towards all things that exist. This is perhaps where mystical experiences touch the rest of life. In James’s opinion, ‘At bottom the whole concern of both morality and religion is with the manner of our acceptance of the universe’ (1902, p. 41).

Two types of mystical experience are sometimes contrasted (Hardy, 1979; Fontana, 2007). Transcendent experiences were more common in Hardy’s collection and entail awareness of a power greater than oneself, whether that is God, a divine spirit or creator, or something completely impersonal. Immanent experiences entail the complete loss of self, whether swallowed up into emptiness or becoming one with the universe or with the divine. Whether there are really distinct types, or whether there are levels or stages of experience, is far from being understood.

Walter Pahnke, an American minister and physician, includes nine items in his list: unity, transcendence of time and space, positive mood, sense of sacredness, noetic quality, paradoxicality, ineffability, transiency, and persisting positive changes in attitudes and behaviour. This list came not from spontaneous mystical experiences but from his work with LSD. Before it was made illegal, he worked with Richard Alpert and Timothy Leary giving LSD to prisoners. He also worked with the terminally ill, giving them just one or a very few trips in carefully and empathically arranged settings. Through these experiences, many at last found peace, love, and the acceptance of both life and death (Pahnke, e.g. 1969). Many decades of drug prohibition subsequently stifled all such use, but at last research is beginning again using psychedelics in terminal care.

The possibility that authentic mystical experiences can occur with drugs offends some religious believers, but many researchers have concluded that they can, including the authors of the largest survey of LSD experiences, The Varieties of Psychedelic Experience (Masters and Houston, 1967). The question was put to the test in the famous ‘Good Friday Experiment’ (Pahnke, 1963, 1967), and in a more recent study (Griffiths et al., 2008), both involving psilocybin (see the main text).

Deep mystical experiences seem to go beyond any narrowly religious view. In The Essentials of Mysticism, the English Christian mystic Evelyn Underhill (1875–1941) sought to ‘disentangle the facts from ancient formulae used to express them’ (1920, p. 1) and came to the essence of mysticism as the clear conviction of a living God in unity with the personal self. Yet she allowed the widest possible latitude in what she meant by ‘God’, agreeing with the fourteenth-century work The Cloud of Unknowing that God may be loved but not thought. So whatever it is that is seen, or understood, or united with, it cannot be described – or even thought about.

How to regard them

We began Chapter 13 with the famous quotation from William James in which he described ‘other forms of consciousness’ and asked how to regard them. We can now return to James’s question: how to regard those other forms of consciousness beyond ‘the filmiest of screens’.

Popular paranormal and supernatural explanations fare badly. They gain little support from the evidence, and face apparently insuperable theoretical obstacles (see Chapters 14 and 15). A related argument is that materialist science falsely ignores our true spiritual nature and that it should embrace the possibilities of other worlds, other dimensions of reality, and conscious selves beyond the physical. We might usefully ask whether this dualist conception of the universe is really more spiritual than a scientific, monist view. And if so, why? Many mystics specifically reject paranormal claims as missing the point. Underhill (1920) calls them ‘off the track’, and James declares that they ‘have no essential mystical significance’ (1902, p. 408n). In Zen Buddhism trainees are taught to ignore visions, miracles, and faith-healing. ‘They are no better than dreams which vanish for ever on awakening. To hold on to them is to become a prey to superstition’ (Kennett, 1972, p. 27).

An alternative, though much less popular, view is that the deepest mystical insights are not only monist and non-paranormal, but are perfectly compatible with the world described by physics (Hunt, 2006). Perhaps the experience of unity or oneness that is so common in mystical and psychedelic experiences is a valid insight into an ultimately unified and integrated universe in which everything affects everything else. This might be summarised as ‘the universe is one, the separate self is an illusion, immortality is not in the future but now, and there is nothing to be done’.

If these insights are valid, what needs overthrowing is not monist science but the vestiges of dualist thinking that still lurk within it. This idea gives no comfort to those who hope for personal survival of death, but it is compatible with our scientific understanding of the universe.

Finally, there remain the most sceptical views: that either we biological creatures are incapable of seeing the truth, or that there are no deep truths to be seen.


James, W. (1902). The varieties of religious experience: A study in human nature. New York: Longmans, Green and Co.

Bucke, R. M. (1901). Cosmic consciousness. Philadelphia: Innes & Sons. See also Sue’s review of a new edition of Bucke’s classic text here .

Fontana, D. (2007). Mystical experience. In M. Velmans and S. Schneider (Eds), The Blackwell companion to consciousness (pp. 163–172). Oxford: Blackwell.

Griffiths, R. R., Richards, W. A., Johnson, M. W., McCann, U. D., and Jesse, R. (2008). Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later. Journal of Psychopharmacology, 22, 621–632.

Hardy, A. (1979). The spiritual nature of man: A study of contemporary religious experience. Oxford: Clarendon Press.

Hunt, H. (2006). The truth value of mystical experiences. Journal of Consciousness Studies, 13(12), 5–43.

Kennett, J. (1972). Selling water by the river. London: Allen & Unwin.

Masters, R.E.L., and Houston, J. (1967). The varieties of psychedelic experience. London: Anthony Blond.

Pahnke, W. (1963). Drugs and mysticism: An analysis of the relationship between psychedelic drugs and the mystical consciousness. PhD thesis, Harvard University.

Pahnke, W. (1967). LSD and religious experience. In R. DeBold and R. Leaf (Eds), LSD, man and society (pp. 60–85). Middletown, CT: Wesleyan University Press.

Pahnke, W. (1969) The psychedelic mystical experience in the human encounter with death. Harvard Theological Review, 62(1), 1–21.

Persinger, M. A. (1999). Neuropsychological bases of God beliefs. Westport, CT: Praeger.

Stace, W. T. (1960). The teachings of the mystics. New York: The New American Library.

Underhill, E. (1920). The essentials of mysticism. London: Dent & Sons.

White, R. A. (1990). An experience-centered approach to parapsychology. Exceptional Human Experience, 8, 7–36.

A biographical note on Evelyn Underhill (1875–1941)

Think of mysticism, and many people think of Evelyn Underhill, who wrote such classics as Mysticism and The Essentials of Mysticism. Born in Wolverhampton, England, she studied history and botany at King’s College for Women, London. She later became the first woman ever to lecture at Oxford University. She began writing stories and poetry before she was 16, and her books on human spiritual consciousness were not just scholarly tomes; Practical Mysticism is subtitled ‘A little book for normal people’. In her thirties she converted to Christianity and during the First World War she became a pacifist. She spent her mornings writing and her afternoons in spiritual direction. When advising people how to live a sane spiritual life, she urged them to make time for quiet meditation or prayer every day, and to meet God in ‘the sacrament of the present moment’. For Underhill mysticism was not about complicated religious doctrines but was to be found directly in the midst of ordinary life and work. Those who knew her say that she lived by the principles she taught, with kindness and devotion to others.

A biographical note on Peter Fenwick (b. 1935)

Peter Fenwick (whose work we cite in Chapters 13 and 15) is a neuropsychiatrist who has spent much of his life working with epilepsy, sleep disorders, and altered states of consciousness. He was born in Nairobi, Kenya, trained in neurophysiology, and then ran the Neuropsychiatry Epilepsy Unit at the Maudsley Hospital in London for ten years. He worked at Broadmoor Hospital, pursuing his interest in automatic and criminal behaviour carried out during unconsciousness, but his particular interest is the problem of mind and consciousness. He has been a meditator himself for nearly forty years and his early studies of the EEG during meditation helped to encourage other scientists to study the effects of meditation.

Fenwick has collected over 2,000 accounts of NDEs and he designed one of the first experiments to test out-of-body vision in hospital cardiac units, but so far with no success. He is now looking into the mental states of the dying. He believes that today’s reductionist neuroscience can adequately explain neither subjective experience nor the wider transcendent states of consciousness which suggest that the whole universe is a single unity. He says he would like to believe that there is continuation of consciousness (though not personal consciousness) after death, but cannot claim to have found definitive evidence.

Chapter 14: Reality and imagination

Chapter Summary

Is there a real divide between reality and imagination? Reality discrimination or reality monitoring are the processes by which we distinguish the two, based on memory, clarity, or availability, but false memories are easily created. True hallucinations are often distinguished from pseudo-hallucinations, illusions, and imagination, but there are no clear dividing lines. Hearing voices is common in schizophrenia; other variants, including visual, bodily, and other auditory hallucinations occur in epilepsy, sleep deprivation, sensory deprivation, and starvation, and with some ritual practices and drugs. Perceptual release hallucinations occur in lone explorers and climbers, and in Charles Bonnet syndrome affecting the newly blind or deaf. In visual hallucinations the ‘form constants’ are common because of the structure of the visual system. Similar visions are now being created artificially, for example by Google’s Deep Dream Generator. Hallucinations provide a challenge to many theories of consciousness including sensorimotor and predictive-processing accounts. Parapsychology is the study of psi phenomena, with methods ranging from simple card guessing to ‘ESP in the Ganzfeld’, remote viewing and remote staring, but is consciousness involved in these phenomena? The chapter concludes with an investigation of other worlds conjured by children with imaginary playmates, shamans taking hallucinogenic drugs, or virtual-reality technology.

Suggested films:

The Truman show, dir. Peter Weir (1998): Truman gradually realises he’s been living his whole life trapped on an island, the solitary star of a live TV show

Dark city, dir. Alex Proyas (1998): all human memories are created anew every night at midnight

Suggested literature:

The magus, John Fowles (1965): a young man goes to teach on a Greek island, and gets sucked into a disorientating ‘god game’ that encompasses his whole existence


The color of the dress according to science (BuzzFeedBlue) (2:50): a quick couple of interpretations

How reliable is your memory? | Elizabeth Loftus (TED) (17:36): the prevalence of false memories and their causes and effects

Deep dream (Google) (Computerphile) (13:42): explains what we do and don’t understand about how the neural nets are functioning, and shows how to play with different training levels

Greenland 2014 Andy Clark on Bayesian predictive coding (Moscow Center for Consciousness Studies) (23:11): concludes that perception can be thought of as controlled hallucination

Ganzfeld (best reaction) (Mullattolee Videography) (4:15); Ganzfeld experiment reaction (must watch!) (SpartanG95) (6:39): some students try it out

Waking up with Sam Harris #68 – Reality and the imagination (with Yuval Noah Harari) (Sam Harris) (1:32:31; interview starts 12:24): includes meditation and drug-taking, storytelling, fact and fiction in history and technology, and religion as virtual reality

Your brain hallucinates your conscious reality | Anil Seth (TED) (17:00): when we agree about our hallucinations, we call it reality

What hallucination reveals about our minds | Oliver Sacks (TED) (18:45): the commonness of hallucinations in visual impairment, and their difference from psychotic hallucinations

What is reality? The human brain – fascinating brain documentary (consciousness & universe) (Howard Corley) (50:28): everything we think of as reality is the brain’s construction


Book review surfing uncertainty (Slate Star Codex): review of predictive processing

Are brains Bayesian? (John Horgan): for and against

Inceptionism: Going deeper into neural networks (Alexander Mordvintsev, Christopher Olah, and Mike Tyka): the mechanisms and significance of the Deep Dream neural networks; see also lots of beautiful examples here

P-Hacker confessions: Daryl Bem and me (Stuart Vyse); Daryl Bem proved ESP is real. Which means science is broken (Daniel Engber): two accounts of how Bem’s ESP research methods helped ignite the replication crisis in psychology. See also Bem, D. J. (2011). Feeling the future: experimental evidence for anomalous retroactive influences on cognition and affect. Journal of Personality and Social Psychology100(3), 407

Activity – Telepathy tests

An impressive demonstration

Stand in front of the group (or ask someone who will be good at acting the part of a psychic to do so) and say something like this: ‘I have the special power of being able to transmit my thoughts to others. I am now going to draw two simple shapes, one inside the other, and I want you to pick up my thoughts.’ Out of sight of the audience, draw a triangle inside a circle, fold the paper carefully and hide it away in a pocket. ‘I am sending my thoughts into your mind. Please try to feel my thoughts and draw what you see.’ When everyone has done their drawing, show them the original.

Typically, about 25% of the audience will have a direct hit, and others will have come close. Ask them how they think it worked.

The answer is population stereotypes. There are, in fact, rather few simple shapes to choose from; triangles and circles are most popular. If you want to rule out the possibility that telepathy was involved as well, you could think about a hexagon inside a square while the audience are drawing. Other examples to use can be found in Marks (2000, pp. 311–317).

A poor experiment

Ask for a volunteer to act as sender, ideally someone who claims telepathic ability. Give them a pen and paper and ask them to leave the room and draw ‘at random’ whatever comes to mind. Agree on a time limit, say two minutes, for the drawing. Everyone else must relax quietly and think about the sender. After two minutes they all try to draw what the sender drew. When they have finished, ask the sender to return and reveal the drawing.

This is the basic method used in ‘thought transference’ experiments in the 1890s. You can use it to explore all the methodological issues that modern parapsychology has grappled with.

  1. Sender choice. If the sender chooses the target, hits can occur because the people know each other, or because they both pick up cues from the environment or from the experimenter. Targets must be randomly chosen.
  2. Judging the result. When two drawings look similar it is impossible to judge chance expectation (you can try using drawings you have collected). Solutions include forced-choice methods using cards or preselected sets of objects, and the more complex free-response methods used for ganzfeld and remote viewing.
  3. Sensory leakage. Could anyone have heard or seen the drawing being made? Could they have changed their own drawing after the target was revealed?
  4. Fraud. Could the sender have told friends in advance, or arranged a code for tapping the answer on the floor? Could the experimenter have set the whole thing up?

Figure 14.1(web) Suppose that in a telepathy experiment the sender draws the picture on the left and the receiver that on the right. How does the experimenter decide whether this is evidence for telepathy or not? The target was a boat and the response was a house – so it must be a miss. But the shapes are remarkably similar – so perhaps it is a hit after all. Problems like this forced the development of better experimental designs, including forced-choice and free-response methods.


Marks, D. (2000). The psychology of the psychic. 2nd ed. Buffalo, NY: Prometheus.

Chapter 15: Dreaming and beyond

Chapter Summary

After briefly surveying the basics of waking, sleeping, and dreaming, this chapter turns from physiology to experience. Dreams are often bizarre, with incongruity, uncertainty, and sudden scene changes, possibly due to failed feature binding. Studies of dream recall and content reveal sex differences in content and show how children’s dreams develop along with their cognitive abilities. Dream events correlate with eye movements, and timing in dreams is roughly equivalent to that in waking. It is even becoming possible to know what someone is dreaming about from their brain activity. But are dreams conscious experiences? Answers based on different theories of consciousness are considered. Beyond dreaming, strange experiences on the borders of sleep include hypnagogic hallucinations, sleep paralysis, and false awakenings. In lucid dreams you know you are dreaming, and expert lucid dreamers can use eye movements to report on their dreams in real time, making possible many useful experiments. Out-of-body and near-death experiences have long been thought to entail a soul or astral body separating from the physical body, but neuroscientific evidence points to a breakdown in the body schema at the temporoparietal junction. Out-of-body illusions induced in virtual reality are revealing other connections between these experiences and our sense of self.

Suggested film:

Waking life, dir. Richard Linklater (2001): a man keeps dreaming that he has woken up

Un chien andalou, Salvador Dalí and Luis Buñuel (1928): a shocking and dreamlike collage of images compiled by the two young surrealists

Suggested literature:

Alice’s adventures in Wonderland, Lewis Carroll (1865): Alice grows drowsy, spies a white rabbit running past, and follows him down a rabbit hole


To sleep, perchance to dream - Crash course psychology #9 (CrashCourse) (10:40): outlines theories of why we sleep and dream

How to induce hypnagogic imagery (SpaceTimeBadass) (7:39): one technique that might help

Dr. Christof Koch on human consciousness and near-death experience research (Follow the Evidence) (46:38): Koch gets a grilling from Skeptiko host Alex Tsakiris on methods for the study of consciousness and the brain, plus science and religion and artificial consciousness

What can lucid dreaming tell us about consciousness? (scienceandnonduality) (43:33): Stephen LaBerge talks about his route to investigating consciousness via dreaming

A beginners guide to lucid dreaming (Ivan Moe) (5:00): instructions for how to induce lucid dreams

Out-of-body experiences, consciousness, and cognitive neuroprosthetics: Olaf Blanke at TEDxCHUV (TEDx Talks) (18:54): the neurology of OBEs, how to induce them, and how to use them to help patients with amputation or spinal cord injury

Susan Blackmore QED 2016 – The new science of out-of-body experiences (qedcon) (53:05): uses her own OBE as a starting point for exploring how they’ve been studied and what we know now (see a similar talk here with good questions from students from 51:20)

Experiencing death: An insider’s perspective (NourFoundation) (1:14:39): conversation on NDEs amongst neurologist Kevin Nelson, psychiatrist Peter Fenwick, orthopaedic surgeon Mary Neal, and professor of medicine Sam Parnia, including Neal’s own NDE and some discussion of OBEs


The terror and the bliss of sleep paralysis (Karen Emslie): a personal account of how to shift from sleep paralysis to lucid dreaming


You are not a self! Bodies, brains and the nature of consciousness (30:04): Thomas Metzinger discusses OBEs and lucid dreams relate to our self, or lack of (transcript also provided)

Additional material from 2nd edition:

Here is a little more on the NDE: Moody’s original description and some attempts to measure the depth of the experience.

Concept – Features of the typical NDE 

A man is dying and, as he reaches the point of greatest physical distress, he hears himself pronounced dead by his doctor. He begins to hear an uncomfortable noise, a loud ringing or buzzing, and at the same time feels himself moving very rapidly through a long dark tunnel. After this, he suddenly finds himself outside of his own physical body [. . .]. Soon other things begin to happen. Others come to meet and to help him. He glimpses the spirits of relatives and friends who have already died, and a loving, warm spirit of a kind he has never encountered before – a being of light – appears before him. This being asks him a question, nonverbally, to make him evaluate his life and helps him along by showing him a panoramic, instantaneous playback of the major events of his life. At some point he finds himself approaching some sort of barrier or border, apparently representing the limit between earthly life and the next life. Yet, he finds that he must go back to the earth, that the time for his death has not yet come [. . .]. He is overwhelmed by intense feelings of joy, love, and peace [. . .]. Later he tries to tell others, but he has trouble doing so. In the first place, he can find no human words adequate to describe these unearthly episodes. He also finds that others scoff, so he stops telling other people. Still, the experience affects his life profoundly, especially his views about death and its relationship to life. (Moody, 1975, pp. 21–23)

Moody provided this account of a prototypical NDE and divided it into fifteen main features. American psychologist Kenneth Ring (1980) then stripped the NDE down to the ‘Core Experience’ consisting of five features: feelings of peace, body separation (OBE), entering the darkness (Moody’s dark tunnel), seeing the light, and entering the light. He developed a ‘Weighted Core Experience Index’ (WCEI) which has a range of scores from 0 to 29. Those with a score of 6 or more are termed ‘core experiencers’.

After retesting and cluster analysis, Bruce Greyson developed a modified version of the scale. This ‘Near-Death Experience Scale’ consists of sixteen questions grouped in four clusters concerned with emotions, cognition, paranormal features, and transcendental aspects. A score of 7 or more counts as having had an NDE, and this criterion is widely used in studies of NDEs.


Moody, R. A. (1975). Life after life. Atlanta, GA: Mockingbird.

Ring, K. (1980). Life at death: A scientific investigation of the near-death experience. New York: Coward, McCann and Geoghegan.

Chapter 16: Egos, bundles, and theories of self

Chapter Summary

The idea that we are unified conscious selves experiencing a stream of consciousness is natural but problematic. For example, cases of multiple personality show that one body can sometimes support more than one self, although theories differ on the nature of those selves.  Two categories of theory are contrasted: ego theories posit a continuing self, whether supernatural or brain-based; bundle theories reject the existence of any continuing self. Thought experiments can help elucidate their implications, from Martians swapping people’s brains to the ‘teletransporter’ which destroys and reconstructs a person’s body and brain in the process: is the replica still the same person? Theories of self include James’s claim that ‘thought is itself the thinker’, and neuroscientific theories that seek the brain basis of self. Damasio distinguishes between a proto-self, core self, and autobiographical self, while others invoke an interpreter or observing self. Other theories include GWTs, Hofstadter’s ‘strange loops’, Strawson’s ‘pearls on a string’, and Metzinger’s ‘self-model theory of subjectivity’. The importance of embodiment and language are considered, along with the idea of self as a social construction or ‘centre of narrative gravity’. As technology develops we consider the prospects for downloaded and enhanced selves and selves in cyberspace.

Suggested films:

Freaky Friday, dir. Mark S. Waters (2003): a mother and daughter do a body swap

Moon, dir. Duncan Jones (2009): a mining station on Mars has a single inhabitant, and when he is injured his identity is thrown into question

Suggested literature:

The strange case of Dr Jekyll and Mr Hyde, Robert Louis Stevenson (1886): Jekyll writes his will, leaving everything to Hyde, but his lawyer knows Hyde to be a cruel and vicious man; what connects them?


What are you? (Kurzgesagt – In a Nutshell) (6:27): is there a line where a pile of your cells stops being you? Includes reflections on constant cellular replacement, cancer, and genetics

Derek Parfit discussing personal identity in the documentary Brainspotting (Christopher Grau) (9:24): assumes the self exists, and asks what kind of thing it is, including dramatisation and discussion of the teletransporter thought experiment

Non-self – A unique teaching of the Buddha | Ajahn Brahmali | 21-11-2014 (Buddhist Society of Western Australia) (1:01:04): an intro to the Buddhist perspective on the flux of experience and experiencer

Confessions of a Buddhist atheist (wimsweden) (6:21): Stephen Batchelor describes his spiritual journey

What is the bundle theory of self? (philosophical definition) ( (7:42): includes Hume and Parfit

Arguments against personal identity: Crash course philosophy #20 (CrashCourse) (9:43): also with Parfit on survival through psychological connectedness, this video includes plenty on the real-world consequences of the flux of identities; see also the follow-up video, #21, on debates about definitions of personhood

PHILOSOPHY – Metaphysics: Ship of Theseus (Wireless Philosophy) (8:06): runs through where the thought experiment can take us in terms of thinking about the persistence of an object over time

Galen Strawson – What are selves? (Closer To Truth) (9:11): the different ways in which people experience self and use the term, and how short-lived he thinks they might be

04 Hofstadter’s strange loops of self (urban983) (7:08): overview of Hofstadter’s notion of how self arises through symbolic abstraction

Hofstadter’s strange loop (Matthew Segall) (9:59): reflections on some of the questions Hofstadter’s book raises, including dualism and the nature of knowledge – and ending in confusion!

Sam Harris: The self is an illusion (Big Think) (6:52): on coming closer to reality by dropping the illusion

Waking up with Sam Harris #96 – The nature of consciousness (with Thomas Metzinger) (Sam Harris) (1:54:38; starts 2:10): wide-ranging discussion including a section on mind-wandering and the discontinuity of self, and (47:25–1:22:48) how the self relates to evolution, culture, and happiness

Antonio Damasio what is the self? (Psychiatry On Line Italia Videochannel) (13:47): his current views on how self and mind arise out of the physical machinery

The ego tunnel: Prof. Dr. Thomas Metzinger at TEDxRheinMain (TEDx Talks) (17:46): why a self is a process not a thing

Self-fulfilling prophecy: Linking belief to behavior (NourFoundation) (1:07:19): discussion between philosopher Simon Critchley, cognitive scientist Shaun Gallagher, physicist V. V. Raman, and professor of medicine Esther Sternberg on how beliefs emerge in behaviours and so how self is shaped by interactions with the physical and social environment

How to create a mind: Ray Kurzweil at TEDxSiliconAlley (TEDx Talks) (21:39): how humans will merge with our technologies to change the nature of self


What makes you you? (Tim Urban): covers multiple theories of what constitutes self, including sections on the teletransporter and split brains

Chapter 17: The view from within?

Chapter Summary

Introspection is essential to the study of subjective experience but is problematic. Some call for a special ‘first-person science’ of consciousness based on irreducible subjective facts; others claim that ‘first-person methods’ such as introspection, meditation, or other personal explorations and training are valid, but science is a collective enterprise and a science of consciousness is no different. The former tend to believe in the validity of the hard problem and the possibility of zombies; the latter do not. We review the methods of traditional phenomenology: the epoché and phenomenological reduction. Neurophenomenology aims to unite modern cognitive science with a disciplined approach to subjective experience, with experiments relating brain imaging to (for example) experiences of time or ‘the structure of nowness’. Velmans’s theory of ‘non-reductive reflexive monism’ claims to do away with the first-/third-person distinction although it faces many criticisms. Experiments such as the ‘body-swap illusion’ bring ‘second-person’ or social neuroscience into play, involving new methods with trained interviewers. Finally, Dennett’s heterophenomenology advocates adopting a neutral stance towards people’s descriptions of subjective experience, much like an anthropologist studying other cultures’ fictions. Working with the personal practices offered throughout this book may help you evaluate these theories and your own experiences.

Suggested film:

Mulholland Drive, dir. David Lynch (2001): juxtaposes identities, experiences, and events though shifting perspectives and surreal events involving amnesia, showbusiness, and death in LA

Suggested literature:

Zen and the art of motorcycle maintenance: An inquiry into values, Robert Pirsig (1974):  a blend of philosophy and fictional autobiography held together by a motorbike journey from Minnesota to northern California


Introduction to introspection (BazarJ) (6:54): the development of Wundt’s and Titchener’s ideas and methods

Introspection as a state of motion: Bart Moeyaert at TEDxFlanders (TEDx Talks) (11:30): a personal take on the prerequisites of self-observation

The unreliability of naïve introspection (Philosophical Overdose) (56:11): Eric Schwitzgebel takes the sceptical position on introspection and our chances of understanding consciousness

“Neurophenomenology” by Evan Thompson (National Core for Neuroethics) (13:37): reasons for the combination of investigative methods that neurophenomenology involves, and where this research programme might go next

Velman’s reflexive model (urban983) (5:01): an outline of the theory

Max Velmans on “From East towards East in five simple steps” (Max Velmans) (1:44:41; presentation ends 54:50): a merging of ‘Eastern’ and ‘Western’ perspectives on consciousness, with a brief summary of reflexive monism from 53:35

Body-swap illusion tricks minds in new study (Associated Press) (2:10): brief footage of some body-swap techniques; see also here for the related Barbie-doll illusion in which size perception is altered

Social neuroscience – Mahzarin Banaji (Serious Science) (13:21): an introduction to an emerging field


Action prediction lab (Patrick Bach): research on ‘predictive social psychophysics’, or how we use predictions to make sense of other people

Additional material from 2nd edition:

This practice is an alternative to the printed version of the P/A consciousness task.

Practice – ‘Is this phenomenal consciousness, access consciousness, or both?’

As many times as you can, every day, ask yourself ‘Am I conscious now?’ Stay with that experience for a little while and then ask ‘Is this phenomenal consciousness, access consciousness, or both?’ You will almost certainly start with a self-reflective state. Can you drop the self-reflection, stop accessing anything for reasoning, inner speech, or action, and become purely P-conscious? Does this help you decide whether Block’s distinction is valid or not?

If you can drop inner speech and reasoning, you might like to go on to a further question: ‘Is there more in phenomenal consciousness than can be accessed? This is a tricky one.

Reminder – Is this phenomenal consciousness, access consciousness, or both?

Chapter 18: Waking up

Chapter Summary

The Buddha claimed to have ‘woken up’, describing a way to end suffering by seeing all phenomena as impermanent and letting go of desire and the illusory self. Many others have described awakening, but do they all undergo the same changes in self and consciousness? Buddhism has interacted more closely with science and psychotherapy than other religions, perhaps because of its relative lack of doctrine and emphasis on personal practice and change. But whereas therapy usually aims to create a coherent sense of self, Buddhist practice aims to transcend it. This chapter explores a variety of methods and spiritual paths with effects on the sense of self, free will, compassion, kindness, and insight. Some people have awoken spontaneously, as in Harding’s ‘headless way’ or mystical experiences close to death; others awake after long practice on a spiritual path. So is there a path to ‘enlightenment’? These varied practices and the science of consciousness all claim to be seeking the truth and breaking out of illusion, but do they mean the same illusions? If so, can we learn to let them go? And what happens when we do?

Suggested films:

Spring, summer, fall, winter . . . and spring, dir. Ki-duk Kim (2003): in a small house floating on a small raft on a small lake live a monk and a boy learning to be a monk

Suggested literature:

The glass bead game (Das Glasperlenspiel), Hermann Hesse (1943) (translated by Richard and Clara Winston): in an educational order in the far future that feels like a medieval past, a strange game is played that fuses the mystical and the rational, but which in its perfect unification of all opposites also threatens to reject the messiness of the real world


Alan Watts: Buddhism and science (1960) [full length] (The Partially Examined Life) (28:30): comparing the two as different forms of knowledge, and including thoughts on awakening)

Alan Watts – If you get one lesson from me, you must learn this (TheSpiritualLibrary) (9:10): the inseparability of self and universe

Life is NOT a journey – Alan Watts (After Skool) (4:00): the universe is playful, and has no destination (music is a better metaphor for your life than a journey)

The real you – Alan Watts (Tragedy & Hope) (3:58): wake up and understand that you are something the whole universe is doing

What are jhanas? Leigh Brasington with Stephanie Nash (Stephanie Nash Meditation) (3:49): a brief description, part of a longer conversation excerpted in various videos here

The jhanas: Buddhist meditative absorptions in modern times (University of Virginia Contemplative Science Center) (1:22:30; presentation ends 55:26): a longer lecture on Brasington’s personal experience of the jhanas from a sutta perspective (see here for an explanation of the two main styles, sutta and visuddhimagga)

Douglas Harding on having no head (alexeysparky) (6:15): how to induce the experience yourself while watching him

The man with no head (Richard Lang) (34:07): documentary on Douglas Harding, with further exploration of headlessness

Concept of enlightenment (Eckhart Tolle) (8:31): enlightenment, or the egoless state, is not an addition to an existing state, nor something to be achieved in the future – the dilemma of all spiritual seekers


A place of silence (BBC Radio 4) (28:46): Sue describes the Zen retreat house Maenllwyd in the remote Welsh hills, and interviews the local farmer, the Zen master John Crook, the Zen cook, and a regular retreatant and ‘work master’

Waking Up: Sam Harris’s podcast


Where’s that confounded ox?! (Jack Engler): two blog posts about on enlightenment and psychotherapy

Additional material from 2nd edition:

These sections offer more detail on paranormal research from the late nineteenth century onwards: how it began, the kinds of phenomena it focused on, and the profound difficulties of doing conclusive research on the paranormal.

From spiritualism to psychical research

In 1848, in Hydesville, New York, two young girls called Kate and Margaretta Fox heard raps and bangings at the end of their bed. Inventing a code of the ‘two taps for yes’ kind, they claimed to be communicating with the spirit of a man buried beneath their wooden house. Neighbours and visitors wanted to communicate with the spirits too, and soon the Fox sisters began giving public demonstrations. This story is usually credited as the start of spiritualism, and the inspiration for the field of psychical research.

There was controversy from the start, with some investigators claiming that the girls had cheated, although they could not say how. Then, in a dramatic public confession in 1888 the Fox sisters demonstrated how they had clicked their toe joints against the bed to produce the sounds, a confession they later retracted. Critics accepted the confessions as the end of the matter, while supporters argued that the sisters were by then penniless and alcoholic, and had been bribed into confessing (Podmore, 1902; Brandon, 1983).

By the end of the nineteenth century, ‘spirit mediums’ were practising throughout Europe and the USA. At some séances, the ‘sitters’ sat in a circle round a table, with their hands placed gently on top. The medium then summoned the spirits, and the table began to move, with the spirits answering questions by tipping the table or banging its legs on the floor.

Among many famous mediums was Eusapia Palladino, an orphan from Naples who apparently levitated herself and other objects, materialised extra limbs, caused inexplicable noises, and made furniture glide about. In 1895 she was caught cheating, but some researchers remained convinced that she had produced genuine phenomena under controlled conditions (Gauld, 1968). The only medium said never to have been caught cheating was Daniel Dunglas Home (pronounced Hume). He worked in reasonably well lit rooms, and was said to have handled live coals without burning, materialised glowing hands, levitated heavy tables, and even floated bodily out of one window and into the next (Gauld, 1968).

Whether any mediums operated entirely without such aids has never been resolved. Some argue that any medium who is caught cheating once must always be presumed to cheat, while others argue that the pressures on even the best of mediums force them to resort to fraud in exceptional circumstances. The same arguments were played out a century later when Uri Geller travelled the world bending spoons, starting watches, and claiming to be able to read minds (Randi, 1975; Marks, 2000), and again when ‘channelling’ appeared as the latest incarnation of mediumship.

Cheating is not the only alternative to a paranormal interpretation. People may misinterpret what they see for many reasons, including illusions, hallucinations, motivated errors, and criterion shifts, and the traditional darkened séance room provides ideal conditions for these to operate.

While most Victorian scientists ignored the antics of spiritualism, some took them seriously, realising the implications for science if the claims were true. As we have seen, Faraday convinced himself that they were false (Chapter 9) but others came to the opposite conclusion.  The famous British chemist Sir William Crookes took photographs of supposedly materialised spirits, and was convinced that Home’s powers implied a new form of energy (Gauld, 1968).


Parapsychology as a discipline was founded by J. B. and Louisa Rhine. Louisa was most interested in spontaneous phenomena and amassed a vast collection of cases. J. B. believed that everyone has some paranormal ability even if it is very weak, and he concentrated on testing ordinary people, rather than only those who claimed special psychic powers.

For each term Rhine described an experimental paradigm for testing it. When testing telepathy, a receiver, or percipient, had to guess the identity of a target being looked at by a sender, or agent. To make the task as easy as possible a set of simple symbols was developed, and made into cards called ESP cards, or Zener cards (after their designer Dr Karl Zener). The symbols were a circle, square, cross, star, and wavy lines; five of each in a pack of 25 cards. For testing clairvoyance, a similar method was used, except that the pack was randomised out of sight of anyone. In precognition experiments its order was determined after the guesses had been made. With five possibilities to choose from, mean chance expectation is one hit in five guesses. In fact, the participants rarely scored much more than five, but by amassing huge numbers of guesses, and applying the appropriate statistical tests, Rhine obtained significant, above-chance, results. This started a controversy that has never really disappeared.

A few years later the young field of parapsychology took another controversial step. One day a gambler came to the Rhines’ laboratory claiming that he could affect the roll of dice by the power of his mind. Rhine turned this into an experimental method, first using hand thrown dice and then a dice-throwing machine. The results were not as impressive as the ESP results but nevertheless seemed to suggest some paranormal ability. Instead of the older term ‘telekinesis’ the Rhines called this ‘psychokinesis’ or PK (Rhine, 1947). They also coined the term ‘psi’ to cover any paranormal phenomena or the hypothesized mechanism underlying them. Thus psi includes both ESP and PK.

These terms have been useful for parapsychology, but their negative definition has caused serious problems. Like psychical research before it, parapsychology is often defined negatively, for example as ‘the scientific study of experiences which, if they are as they seem to be, are in principle outside the realm of human capabilities as presently conceived by conventional scientists’ (Irwin and Watt, 2007, p. 1). All forms of psi are defined as communication without the use of the normal senses or forces. This means that psi researchers have to go to ever greater lengths to rule out all ‘normal’ interactions, and critics can always think of new reasons why the phenomena might be normal after all. Another consequence of these definitions is that parapsychology keeps shrinking because when phenomena such as hypnosis, hallucinations, or lucid dreams are explained by psychology, they cease to count as paranormal.

The controversy provoked by the Rhineses spread around the world and prompted numerous methodological criticisms. In the first experiments the cards were held up in front of receivers and the patterns could be faintly detected through the back. Dice had to be checked for bias, the subjects separated more carefully, and the possibility of recording errors dealt with. The most important problem, however, was the randomisation. In the early psychical research experiments, senders had been allowed to choose what to send; for example, they were asked to draw the first thing that came to mind. This meant that receivers could appear to be telepathic if they knew the sender well, or could guess what the sender might choose. Using ESP cards ruled out this problem, but shuffling them proved to be an inadequate method.

For this reason, mechanical shuffling devices were invented, or log tables were used to decide the order of the cards. Nowadays parapsychologists use random number tables, or random number generators (RNGs) based either on computer pseudo-random algorithms, or on truly random processes such as radioactive decay. All this is necessary to rule out any systematic biases that might produce spurious correlations between the target sequences and the order of guesses. Finally, the Rhineses’ statistical methods were criticised, until in 1937 the President of the American Institute of Mathematical Statistics declared that if the experiments were performed as stated, the statistical analysis was essentially valid (Rhine, 1947).

Soon others, appreciating the importance of these findings if they were true, tried to replicate them. The story of one man’s attempts illustrates all the trials and tribulations of research in parapsychology then, and since.

Samuel G. Soal was a mathematician at Queen Mary College, London. Inspired by Rhine’s results, he spent five years accumulating thousands of guesses with several participants, and yet was completely unsuccessful. He would probably have given up except that another British researcher, Whateley Carington, claimed that in his experiments the participants sometimes picked the target one before or one after the intended target – a phenomenon that later became known as the ‘displacement effect’. So, following Carington’s suggestions, Soal laboriously checked all his guesses against the symbols before and after the original target. To his surprise, the results of one participant, Basil Shackleton, showed highly significant scores for the card ahead.

Retrospective ‘fishing’ in data cannot prove anything, but it can provide predictions for future experiments. So Soal invited Shackleton back for more tests, predicting that the same pattern would be found. To ensure that Shackleton could not cheat, rigid controls were employed, and respected scientists were invited in to observe all the experiments. This time Soal was successful. Indeed, the odds against these new results occurring by chance were 1037, that is, ten followed by thirty-seven zeros (Soal and Bateman, 1954). These experiments became the mainstay of the evidence for ESP and, because of the apparently impeccable controls and powerful results, many scientists and philosophers took them seriously (West, 1954). Even Alan Turing was concerned at the havoc ESP would play with his proposed test for an intelligent machine (Chapter 12): ‘These disturbing phenomena seem to deny all our usual scientific ideas. How we should like to discredit them! Unfortunately the statistical evidence, at least for telepathy, is overwhelming’ (1950, p. 66).

But this was not the end of the story. Other researchers failed to replicate the Rhine–Soal results and some began making accusations of fraud. Then one of Soal’s senders claimed that she had seen Soal changing figures in the target list. This provoked a flurry of reanalyses and investigations of Soal’s work, none of which either conclusively incriminated or exonerated him.

In 1978 Betty Markwick, a member of the Society for Psychical Research, joined those determined to clear Soal’s name. She had access to a computer (rare in those days) and began to search through the log tables for the sequences Soal had used for his randomisation. She knew that if she could match up the log tables with the actual target sequences, she could prove that he had not changed them. She failed. But she did not give up. Instead she began a long and tedious search through his target sequences by hand. To her surprise she came across some repeated sequences which would be very unlikely to occur in the log tables. Then, even more surprising, she found sequences that appeared to be repeated but with a few extra numbers added in. She returned to the computer and searched again for just such sequences.

When she did so she found that all of the extras corresponded to hits and when these extras were removed the results fell to chance (Markwick, 1978). It had taken a quarter of a century of hard work to solve the mystery, and in that time thousands of people had been taken in.

Parapsychologists generally accepted Markwick’s conclusions, but many still believed that other results were genuine. They found ‘signs of psi’ such as ‘psi missing’ (scoring consistently below chance), the ‘decline effect’ (a decline in scores through the course of an experiment or session), and the ‘sheep–goat’ effect (believers in psi score higher than disbelievers) (Schmeidler and McConnell, 1958).

The sheep–goat effect suggested that belief and motivation might be important, and if experimenters needed these qualities too, the many failures to replicate might be explained in terms of a ‘psi-mediated experimenter effect’. Experimenter effects have often been found in parapsychology, and parapsychologist John Palmer claims that ‘the strongest predictor of ESP results generally is the identity of the experimenter’ (Palmer, 2003, p. 61). These effects might occur because some experimenters make more errors, because some cheat, because of differences in the experimenter–participant relationship, or because of a psi-mediated effect.

The way to test this is to run exactly the same experiment with two different experimenters. A pioneering experiment of this kind gave successful results for the believing experimenter but not for the psi-inhibitory experimenter (West, 1954), as did later experiments in which sceptic Richard Wiseman compared results with parapsychologist Marilyn Schlitz (1998). But as is so common in parapsychology, this experimenter effect did not prove replicable (Schlitz et al., 2006) and critics argue that the differences in results depend on how carefully the experiments are controlled, not on their experimenters’ beliefs.

This brief history of the first century of research shows how difficult parapsychology is. The results never seem to be good enough to convince the sceptics, and yet the sceptics cannot prove the negative: that negatively defined paranormal phenomena do not exist.

ESP – Extrasensory perception

Traditional card guessing experiments are exceedingly boring. The participants get tired, and the significance of the results can only be demonstrated statistically. By contrast, reports of psychic dreams, premonitions, and real-life ESP are exciting. The challenge for modern parapsychology was to capture this in the lab.

One of the best-known attempts was the ESP-dream research at the Maimonides Medical Center in New York (Ullman, Krippner, and Vaughan, 1973). This pioneered ‘free-response’ methods instead of ‘forced-choice’. Sleeping participants were monitored in the lab, woken during REM sleep, and then asked to freely report their dreams (rather than having to choose ‘square, circle, circle’ and so on). While they were sleeping, an agent looked at a randomly chosen target such as a colourful picture or a sequence of slides. Dramatic correspondences were found between the dreams and targets but, as in the early thought transference experiments, this presented the problem of estimating how frequently such coincidences would be expected by chance. The solution was to provide a small set of possible targets (usually just four or six). Using this method, either the participant or an independent judge matched the dream imagery against each of the set in turn, and tried to pick the true target. In this way, simple statistics can be applied to an interesting free response experiment.

The results for the early dream studies were well above chance and created great excitement within parapsychology, but other laboratories failed to replicate the findings, and laboratory dream studies slipped out of favour. Later dream studies were predominantly done in people’s homes and without monitoring equipment and did provide some significant results but not consistently so. A later review concluded ‘that dream ESP remains a promising, if somewhat neglected, area for parapsychological research’ (Sherwood and Roe, 2003).

Perhaps more importantly, the basic method was later adapted in other ways – for example in the ‘remote-viewing’ paradigm and ESP in the ganzfeld (see the main text).

PK – Psychokinesis

Psychokinesis, or PK, is the ability to affect objects or events without touching them or using any ordinary force. Research into PK includes studies of table tipping and levitation, the early experiments with dice, studies of metal bending with Uri Geller and the many children who emulated him (Randi 1975; Marks, 2000), and studies of distant mental influence on living systems (DMILS) (Braud and Schlitz, 1989). A meta-analysis of the ‘effects of consciousness on the fall of dice’ showed barely significant overall effects (Radin and Ferrari, 1991). However, the majority of modern PK research is on micro-PK, the supposed effect of the human mind on microscopic, quantum-mechanical, or probabilistic systems.

Micro-PK research began in the 1970s with experiments in which participants willed a light to move either clockwise or anti-clockwise round a circle.  The direction was controlled by a truly random process: particles emitted from a strontium-90 radioactive source. Since then many other kinds of PK machine have been used, not just to demonstrate PK but to test competing theories.

The ‘observational theories’, which are derived from quantum physics, describe psi not as a force operating in real time, but as a shift in probabilities caused by conscious observation of the results. So according to these theories, PK occurs at the moment when feedback is given, not when the particles are emitted. This extraordinary effect was apparently confirmed in an experiment using pre-recorded targets (Schmidt, 1976). A radioactive source generated random numbers and these were converted into clicks on the left and right channels of an audio tape. The tape was later played to participants whose task was to influence the clicks to one side or the other. The tapes were then stored for hours, days or even weeks before playing to the participants. When they were played, an excess of clicks in the chosen direction was found. To rule out the possibility that participants were physically affecting their tape by ordinary PK, copies of the original output were kept, unseen by anyone, and compared with the tape after the experiment was completed. In some experiments participants were given the same targets four times over, and in this case the retro-PK effect was stronger.

Dutch parapsychologist Dick Bierman has extended this method to try to test the subjective reduction interpretation of the measurement problem in quantum mechanics. That is the idea that consciousness collapses the wave function (Chapter 5). He measured auditory evoked potentials while participants listened to clicks from previously unobserved radioactive decay events and compared these with responses to previously observed events that presumably were already collapsed to a singular state. In early studies a significant difference in brain responses between the two was seen but, as so often happens in parapsychology, the results failed to replicate (Bierman and Whitmarsh, 2006).

If time-displaced PK effects like this seem impossible, it may be worth bearing in mind that all forms of psi are, from some perspectives, impossible. So perhaps probabilistic quantum effects are no more impossible than ‘ordinary’ psi.

At the Princeton Engineering Anomalies Research Lab, or PEAR, American engineer Robert Jahn and his colleagues collected enormous amounts of data using quantum mechanical random number generators (RNGs). All data were automatically recorded, direction of aim was counterbalanced, and baseline conditions were recorded for control. Other researchers have used similar methods and, as in the case of the ganzfeld, meta-analysis has been used to try to determine whether there is an overall effect in the entire database.

The first major meta-analysis included nearly 600 RNG–PK studies (Radin and Nelson, 1989). It found chance results in control conditions but significant deviations from chance in experimental conditions. This effect, though exceedingly small in size, was consistent throughout the database, not related to methodological quality, and not dependent on the work of just a few investigators. The authors interpreted this as ‘evidence for consciousness-related anomalies in random physical systems’ (1989, p. 1499). From this and two further meta-analyses, they concluded that consciousness has a direct effect on matter. However, there followed debates about which experiments should have been included, the heterogeneity of the studies, the importance or otherwise of various potential flaws in the methods, and so on. A subsequent meta-analysis by different authors revealed a very much smaller effect size, and one that could be reduced to chance levels by the addition of just a few more non-significant studies (Steinkamp, Boller, and Bösch, 2002). Thus, the whole question of the existence of micro-PK remains in doubt.

Those parapsychologists who are convinced of the evidence for PK frequently make explicit claims that consciousness is involved. This makes sense in terms of their underlying theories. For example, some are dualists and believe that non-physical mind, or consciousness, acts as a force on the physical universe. Others favour theories based on quantum physics, suggesting that consciousness directly affects the collapse of the wave function, or that consciousness is independent of time and space. Radin (2006) builds on the idea of quantum entanglement, speculating that conscious awareness might be related to entangled particles in the brain and that ‘entangled minds’ could result in experiences of ESP and PK. But there is little in the experiments themselves that directly tests these claimed connections with consciousness.

In a typical PK experiment the participant tries to influence a visual or auditory display controlled by an RNG. A bias in the intended direction is then taken as evidence for PK. But there is a big leap from this correlation to a causal explanation involving ‘the effect of consciousness’. Even in Bierman’s experiments the controls done do not show that the intention has to be a conscious one, and indeed comments in many published papers suggest that some participants actually do better when not thinking about the task, or when doing something completely different like reading a magazine, suggesting that conscious intent might even be counter-productive.

Controls do show that the participant is necessary but not what is relevant about their presence. It might be their unconscious intentions or expectations, it might be some change in behaviour elicited by the instructions given, or it might be a mysterious resonance between the RNG and some unidentified neural process or brain function. To find out whether the effect is due to consciousness, relevant experiments would have to be done. So far they have not been.

The power of coincidences

I woke up from a terrible dream with an overpowering sense of dread. I was in the hospital . . . running . . . endless corridors . . . openings left and right . . . greenish light all around . . . I knew I must keep running. Then I was right by a hospital bed and there was my best friend, Shelley, lying there covered in blood and bandages. Dead.

Three hours later I got the phone call. Shelley had been killed instantly in a car crash the night before. It must have happened at exactly the time I dreamed about her.

This experience is interesting primarily for the apparent involvement of telepathy or precognition. Like many of the most common psychic experiences, this one comes down to a matter of probabilities.

Judging the likelihood of any given coincidence is notoriously hard, so it is possible that people judge chance coincidences as far more unlikely than they really are, and then look for explanations. If no good explanation is available, they assume the event was paranormal. Consistent with this hypothesis, people who are better at making probability judgements are less likely to report psychic experiences or to believe in the paranormal. Believers are also more likely to detect images in ambiguous figures or meaningful signals in noise (Blackmore and Troscianko, 1985; Brugger and Taylor, 2003).

People also remember the details that come true and forget the rest. In the example above, the dreamer saw Shelley in a hospital bed, but since she died at the scene she was probably never bandaged and not even in hospital, but such details are easily overlooked in later memories.

One British statistician used some simple assumptions to calculate the odds of anyone dreaming that a named person died when that person actually did die within 12 hours of the dream. Given the number of people who die every day, and assuming that each person only has one dream in their entire lifetime in which someone they know dies, he calculated that one such coincidence will happen to someone in Britain every two weeks. If you were that person, wouldn’t you be convinced it was paranormal?


There probably are no paranormal phenomena. In spite of a century and a half of increasingly sophisticated research, we still cannot be sure. However, we may safely conclude this much: if psi exists, it is an extremely weak effect. No progress has been made at all in identifying how it works or in developing theories to explain its peculiarities, and there is no direct evidence that ESP and PK are effects of consciousness.

Some people seem to think that rejecting the paranormal also means rejecting spirituality and exceptional human experiences. As we have seen (Chapters 13, 15, and 18), this is not necessary at all. Although some spiritual traditions claim miracles and supernatural powers, many decry chasing after the paranormal, and there is nothing intrinsically spiritual about the ability to bend spoons at a distance, levitate one’s body, or pick up thoughts from someone else’s mind.

And there is one last curious fact to note. Most of what we have learned in this book seems to point away from the idea of consciousness as a separate entity, or as having any powers of its own to affect the world. Yet this ‘power of consciousness’ is what many parapsychologists explicitly seek. In this way, parapsychology seems to be growing ever further away from the progress and excitement of the rest of consciousness studies.


Bierman, D., and Whitmarsh, S. (2006). Consciousness and quantum physics: Empirical research on the subjective reduction of the statevector. In J.A. Tuszynski (Ed.), The emerging physics of consciousness (pp. 27–48). Berlin: Springer.

Blackmore, S. J., and Troscianko, T. S. (1985). Belief in the Paranormal: Probability judgements, illusory control and the ‘chance baseline shift’. British Journal of Psychology, 76, 459–468

Brandon, R. (1983). The spiritualists. London: Weidenfeld and Nicolson.

Braud, W., and Schlitz, M. (1989). A methodology for the objective study of transpersonal imagery. Journal of Scientific Exploration, 3, 43–63.

Brugger, P., and Taylor, K. I. (2003). ESP: Extrasensory perception or effect of subjective probability? Journal of Consciousness Studies, 10(6–7), 221–46.

Gauld, A. (1968). The founders of psychical research. London: Routledge and Kegan Paul.

Irwin, H. J., and Watt, C. A. (2007). An introduction to parapsychology. 5th ed. Jefferson, NC: McFarland.

Marks, D. (2000). The psychology of the psychic.2nd ed. Buffalo, NY: Prometheus.

Markwick, B. (1978). The Soal–Goldney experiments with Basil Shackleton: New evidence of data manipulation. Proceedings of the Society for Psychical Research, 56, 250–281.

Palmer, J. (2003). ESP in the ganzfeld. Journal of Consciousness Studies, 10(6–7), 51–68.

Podmore, F. (1902). Modern spiritualism: A history and a criticism. London: Methuen.

Radin, D. (2006). Entangled minds: Extrasensory experiences in a quantum reality. New York: Simon & Schuster.

Radin, D. I., and Ferrari, D. C. (1991). Effects of consciousness on the fall of dice: A meta-analysis. Journal of Scientific Exploration, 5(1), 61–83.

Radin, D. I., and Nelson, R. D. (1989). Evidence for consciousness-related anomalies in random physical systems. Foundations of Physics, 19, 1499–1514.

Randi, J. (1975). The truth about Uri Geller. Buffalo, NY: Prometheus.

Rhine, J. B. (1947). The reach of the mind. New York: Sloane.

Schlitz, M., Wiseman, R., Watt, C. and Radin, D. (2006). Of two minds: Sceptic–proponent collaboration within parapsychology. British Journal of Psychology, 97, 313–322.

Schmeidler, G. R., and McConnell, R. A. (1958). ESP and personality patterns. New Haven, CT: Yale University Press

Schmidt, H. (1976). PK effect on pre-recorded targets. Journal of the American Society for Psychical Research, 70, 267–292.

Sherwood, S. J., and Roe, C.A. (2003). A review of dream ESP studies conducted since the Maimonides Dream ESP programme. Journal of Consciousness Studies, 10(6–7), 85–109.

Soal, S. G., and Bateman, F. (1954). Modern experiments in telepathy. London: Faber & Faber.

Steinkamp, F., Boller, E., and Bösch, H. (2002). Experiments examining the possibility of human intention interacting with random number generators: A preliminary meta-analysis. Proceedings of the 45th Convention of the Parapsychological Association, Paris, August 2002.

Ullman, M., Krippner, S., and Vaughan, A. (1973). Dream telepathy. London: Turnstone.

West, D. J. (1954). Psychical research today. London: Duckworth.

Relaxation and stress reduction

Both meditation and mindfulness have been said to reduce stress, but evaluating these claims has proved unexpectedly tricky.

Best known are probably Transcendental Meditation’s claims to be ‘the single most effective technique available for gaining deep relaxation, eliminating stress, promoting health, increasing creativity and intelligence, and attaining inner happiness and fulfillment’. Because of these claims, doctors and therapists sometimes prescribe meditation as a method of dealing with hypertension and other stress-related diseases, but does it work?

In 1983 American psychologist David Holmes conducted a simple experiment to compare the arousal-reducing effects of meditation with the effect of rest in ten people who had never meditated before and ten certified teachers of TM. Each person first sat quietly for five minutes. Then the meditators meditated for twenty minutes and the non-meditators rested. Finally, they sat quietly for another five minutes. The results were striking. Both meditation and resting reduced arousal equally. Holmes then tracked down many previous experiments and found that most showed the same results, that when the correct controls are employed, just resting is as relaxing as meditation. He also exposed people to stressful situations and found no evidence that the experienced meditators coped better (Holmes, 1987).

Holmes’s research caused a storm of protest from advocates of TM, and heated debates ensued. These disputes are difficult to resolve because of the many methodological issues involved. One concerns which measures of stress to study, and many have been tried, including heart rate, breathing rate, blood oxygen and carbon dioxide levels, EEG and many more. If one measure shows no effect, people can turn to a different one.

Another issue concerns which kind of meditation to use, because different methods may have different effects. By far the majority of studies have used TM, and this is appropriate here because of TM’s strong claims to reduce stress. However, this raises special difficulties. Most TM research is done by TM practitioners and teachers, who have been trained over long periods and have committed their lives and a great deal of money to the TM organisation. Many of their studies come from the Maharishi International University in Fairfield, Iowa, or from other TM universities around the world, and many are published in their own journals. Although an increasing number are published in peer-reviewed journals and are therefore open to scrutiny, doubts will always be raised when the financial stakes are so high.

One example of the problem is a study reported in the press as showing that ‘Transcendental Meditation buffers students against college stress’. In fact, this study compared students trained in TM for ten weeks with non-meditating controls who were to be trained later. Differences were found on a ‘Brain Integration Scale’ devised for testing TM and not otherwise validated as being relevant to stress, but no differences were found in heart rate variability, which was the only other relevant variable tested (Travis et al., 2009). There is no doubt that practicing TM has effects, but whether those include relaxation or stress reduction is very much open to question.

Returning to more general methodological problems, all research into meditation has to confront several design issues, reviewed here in relation to the research on stress. One decision is whether to make within-subject or between-subject comparisons. In within-subject designs, meditators act as their own controls, perhaps sitting quietly first and then meditating. Using this method, reductions in arousal are usually found, but these must be compared with what would happen if the meditators just rested instead – or perhaps took part in some other relaxing alternative. Only if meditation is more relaxing than, say, listening to music or dozing in a comfy chair, can the claims be supported. A problem for within-subject designs is that it may be impossible to prevent meditators from meditating when they are resting, listening to music, or dozing in a comfy chair. One could then argue that the lack of any difference was because they meditated in both conditions. But if you try to avoid this by using novice meditators you may get no effect because they do not know how to meditate properly.

Between-subject designs compare two different groups of people, as Holmes did. This makes sure that the non-meditators are not meditating by mistake, but now the problem is how to choose the appropriate control group. If you use experienced meditators they are likely to be rather special kinds of people, and may react differently to stress from other people. For example, those who take up meditation are more anxious and neurotic than average, and more likely to use recreational drugs. Those who give up are more introverted, have a more external locus of control, and start with lower expectations of meditation (Delmonte, 1987).

Nevertheless, it is possible to deal with some of these problems and reach at least tentative conclusions. Farthing concluded that the evidence ‘shows either no effects of meditation or that the effects of meditation (relaxation, anxiety reduction) can also be achieved by other methods and are not necessarily produced by the meditation technique per se’ (Farthing, 1992, p. 440). Holmes (1987) concluded that the use of meditation for stress reduction was simply not justified by the evidence.

Similar difficulties apply to the claims that MBSR aids recovery and reduces stress, anxiety, and pain. For example, it is difficult to design a control treatment to avoid placebo effects, and the diversity of the conditions MBSR is used for makes comparisons difficult. The programme also includes both meditation and physical exercise, making it difficult to know which, if either, is causing any effects found.

The many studies of MBSR have been assessed using meta-analysis. One looked at general effects on health and well-being, including self-reported depression, anxiety, quality of life, and coping style. After excluding studies with serious methodological flaws, only twenty out of sixty-four remained, and only half of these used an adequate control group, but these showed consistent and substantial improvements. The authors concluded that ‘Only large-scale and sound research in the future will be able to bridge this schism between methodological deficiencies, on the one hand, and the potential promises of mindfulness training, on the other’ (Grossman et al., 2004, p. 40). A second meta-analysis reviewed all studies published in peer-reviewed journals that used a control group and measured depression and anxiety – fifteen altogether. The results were equivocal and the authors concluded that ‘MBSR does not have a reliable effect on depression and anxiety’ (Toneatto and Nguyen, 2007, p. 260). A more recent meta-analysis (Eberth and Sedlmeier, 2012) found some effects of the full MSBR programme (which includes yoga, discussion sessions, homework assignments, etc.) on psychological well-being, but not for the meditation component alone, which only affected mindfulness-related measures. This suggests that it might be elements other than the meditation itself which produce the therapeutic effects.

This may all seem rather surprising given the popularity of these methods and the many claims made. One reason may be expectation and placebo effects, another may be that the measures used do not capture real changes, and another may be that real changes take a long time and require meditation over many years, which makes research much harder. Whatever the reasons, we should not lightly assume that meditation or mindfulness are a quick route to relaxation and freedom from stress.

Finally, claims for meditation as a stress reducer must be tempered by appreciating its potential dangers. TM can exacerbate existing depression, increase anxiety and tension, and produce agitation and restlessness. Training in meditation is not a calm and steady process of increasing relaxation, but a deep confrontation with oneself, and beginners may be overwhelmed. People who are frail, unhappy, neurotic, and deeply afraid may have catastrophic reactions to facing themselves. Although they want to feel better, embarking on serious spiritual inquiry may initially make them worse (Epstein and Lieff, 1986; Delmonte, 1987; Engler, 2003).

Meta-analyses of a range of meditation types have also had to exclude the vast majority of evaluated studies on grounds of methodological weakness. One (Goyal et al., 2014) found some effects on anxiety, depression, and pain, but found no significant effects relative to other active treatments or therapies for those trials which compared the two, and emphasised the need to treat meditation as a lifelong learning process, not a quick health fix. Another (Sedlmeier et al., 2012) found medium to large effects on emotionality and relationship issues, and medium effects on attention, but highlighted the lack of solid theoretical framework, in particular the blurry boundary between uses of meditation as psychotherapy and/or personal and spiritual development.


Delmonte, M. M. (1987). Personality and meditation. In M. West (Ed.), The psychology of meditation (pp. 118–132). Oxford: Clarendon Press.

Eberth, J., and Sedlmeier, P. (2012). The effects of mindfulness meditation: a meta-analysis. Mindfulness3(3), 174–189.

Engler, J. (2003). Being somebody and being nobody: A re-examination of the understanding of self in psychoanalysis and Buddhism. In J. D. Safran (Ed.), Psychoanalysis and Buddhism: An unfolding dialogue (pp. 35–79). Boston: Wisdom.

Epstein, M., and Lieff, J. (1986). Psychiatric complications of meditation practice. In K. Wilber, J. Engler, and D. Brown (Eds), Transformations of consciousness: Conventional and contemplative perspectives on development (pp. 53–63). Boston, MA: Shambhala.

Farthing, G. W. (1992). The psychology of consciousness. Englewood Cliffs, NJ: Prentice Hall.

Goyal, M., Singh, S., Sibinga, E. M., Gould, N. F., Rowland-Seymour, A., Sharma, R., . . . and Ranasinghe, P. D. (2014). Meditation programs for psychological stress and well-being: A systematic review and meta-analysis. JAMA Internal Medicine174(3), 357–368.

Grossman, P., Niemann, L., Schmidt, S., and Walach, H. (2004). Mindfulness-based stress reduction and health benefits: A meta-analysis. Journal of Psychosomatic Research,57, 35–43.

Holmes, D. S. (1987). The influence of meditation versus rest on physiological arousal. In M. West (Ed.), The psychology of meditation (pp. 81–103). Oxford: Clarendon Press.

Sedlmeier, P., Eberth, J., Schwarz, M., Zimmermann, D., Haarig, F., Jaeger, S., and Kunze, S. (2012). The psychological effects of meditation: A meta-analysis. Psychological Bulletin138(6), 1139.

Toneatto, T., and Nguyen, L. (2007). Does mindfulness meditation improve anxiety and mood symptoms? A review of the controlled research. Canadian Journal of Psychiatry, 52(4), 260–266.

Travis, F., Haaga, A. F., Hagelin, J., Tanner, M., Nidich, S., Gaylord-King, C., Grosswald, S., Rainforth, M., and Schneider, R. H. (2009). Effects of Transcendental Meditation practice on brain functioning and stress reactivity in college students. International Journal of Psychophysiology, 71, 170–176.

And here is a discussion of some of the more outlandish claims made for TM.

Siddhis and psychic powers

Dramatic claims are made for some forms of meditation. Siddhis are supernatural or paranormal powers such as prophecy, levitation, astral projection, and ‘control over others and the forces of nature’, and they are claimed within TM, Hinduism, yoga, and some forms of Buddhism.

TM makes two claims of this kind and has a special sidhi programme open only to those at the highest level of attainment within the organisation. The first is a form of levitation called ‘Yogic flying’ or ‘Vedic flying’. It begins with a bounce or hop, followed by the body lifting into true flying, while the adept experiences exhilaration, lightness, and bliss. This is said to coincide with moments of maximum EEG coherence, which implies that the effect must be predictable enough to be caught during EEG testing. There are photographs of people apparently floating above their meditation cushions, but these could have been taken at the height of the initial bounce or hop, and no outsiders have ever been shown the flying.

The second claim is the ‘Maharishi effect’: that if enough people meditate together in one place, their combined field of consciousness can bring peace to everyone else, and even to the whole planet. According to the Maharishi’s ‘unified field theory of consciousness’, the field of pure consciousness underlies the laws of quantum mechanics and is what people tap into when they meditate. This allows them to alter the statistical averaging at quantum mechanical levels, making possible such local effects such as levitation, and global effects such as increasing peace and love in the world. Evidence in support of the Maharishi effect includes falling crime rates and increasing social cohesion in areas where TMers congregate, such as at TM universities and the headquarters in Fairfield, Iowa. Critics argue that appropriate control areas and cities have not been studied, and that some of the effects were only to be expected. For example, when the TM organisation buys up a college previously full of students who own cars and drink alcohol and fills it with older committed TMers who stay in and meditate for several hours a day, obviously crime rates will fall. No research can fairly test TM’s claims to have brought down the Berlin wall, ended the Gulf War, caused stock-market rises, or contributed to the collapse of the Soviet Union.

As we have seen, evidence for psychic powers in general is weak, and many mystics and meditators dismiss supernatural claims as beside the point if one’s objectives are wisdom and transcendence. Even so, psychic phenomena can be very tempting and there have been many cases of teachers abusing the power such claims seem to give them.