The Astonishing Hypothesis

The Astonishing Hypothesis: The Scientific Search for the Soul is a 1994 book by Francis Crick which attempts to establish a basis for the scientific study of consciousness.

Visual Awareness

 * Modern computers... can simulate only a relatively small number of... neurons and their interconnections. Nevertheless, these primitive models... often show surprising behavior, not unlike some of the behavior of the brain. They help provide us with new ways of thinking about how the brain works.


 * What is the "neural correlate" of visual awareness?


 * The brain's operating system is probably not cleanly located in one special place. ...It may involve separate parts of the brain interacting together, and the active information in one of these parts may be distributed over many neurons.


 * Recall the old line: How do I know what I think till I hear what I say.


 * Consciousness can undoubtedly take many forms, depending on which parts of the cortex are involved.


 * What is the "neural correlate" of consciousness?


 * Our experience of perceptual unity... suggests that the brain in some way binds... all those neurons actively responding to different aspects of a perceived object. ...neurons that respond to the motion... hue... words... and possibly the memory traces associated with knowing whose face it is all have to be "bound" together... as neurons that jointly generate the perception...


 * What is especially unclear is whether, in focused awareness, we are conscious of only one object at a time, or whether our brains can deal with several objects simultaneously.

Some Experiments

 * Attention... is not just a psychological concept. Its effects can be seen at the neuronal level.


 * Any experimental work on consciousness has, in the past, been looked on with grave suspicion, not only by psychologists and neuroscientists but by the medical profession.


 * In the somatosensory system, a weak or brief signal can influence behavior without producing awareness, while a stronger one... can make awareness occur.

Mainly Speculation

 * The real world is constantly there, so the brain can refer to it to check any provisional judgements it may have made...


 * Although the dendrites and axon of a neuron often extend over several layers, the layer in which its soma is located is probably determined genetically... (The details of the neuron's connections, on the other hand, are greatly influenced by experience.)


 * For neurons, the mechanism is likely to be a winner-take-all process... that is ...only one (or a few) ...fires more vigorously ...while all the others are forced to fire more slowly or not at all.


 * Memory can be of two general types. When you are actively remembering something there must be neurons firing... However... latent memories will not, in general, require the relevant neurons to be firing. The memory is stored... because the strength of many synaptic connections were altered... in such a way that the requisite neural activity could be regenerated, given a suitable clue.


 * When an axonal spike arrives at a synapse it alters the synapse almost instantaneously, so that its synaptic strength is increased. ...The increase in synaptic strength then decays ...These are the sort of times involved in short-term memory.

Oscillations and Processing Units

 * The binding problem—how to bind all the neurons firing to different features of the same object (or event), especially when more than one object is perceived... Binding is important because it seems necessary for at least some types or awareness. ...it was suggested that binding might be achieved by the correlated firing of the neurons concerned. A rather simple kind of correlated firing is that the neurons involved fire together in some sort of rhythm.


 * Some neurons in the visual cortex fire in a somewhat rhythmical manner when they become active due to a suitable stimulus in the visual field. ...synchrony can occur between neurons in different cortical areas and also... between the two halves of the cortex.


 * Synchronized [neuron] firing on, or near, the beat of gamma oscillation might be the neural correlate of visual awareness.


 * There may be several forms of visual awareness and, by extension, even more forms of consciousness in general.


 * An idea I call the Processing Postulate states that each level of visual processing is coordinated by a single thalamic region. ...Not enough is yet known... to decide whether the Processing Postulate is true or not.


 * We may be using the terms conscious and unconscious for too many somewhat distinct activities.


 * The idea that the thalamus is a key player in consciousness is not a new one. It was suggested much earlier Wilder Penfield. ...James Newman and Bernard Baars have extended the latter's ideas...


 * If the thalamus is indeed the key to consciousness, the reticular nucleus is likely to play some part in the control of consciousness.


 * Each set of... cortical areas is strongly connected to just one small region of the thalamus. Such a region coordinates the activities of its associated cortical areas by synchronizing their firing.


 * So much for a plausible model. I hope nobody will call it the Crick Theory of Consciousness. ...If anyone else produced it I would unhesitatingly condemn it as a house of cards. Touch it, and it collapses.

Dr. Crick's Sunday Morning Service

 * The correct way to conceptualize consciousness has not yet been discovered and... we are merely groping our way toward it.


 * It is premature to try to describe how the brain really works using just a black-box approach, especially when it is couched in the language of common words or the language of a digital programmable computer. ...To understand the brain you must understand the neurons and especially how vast numbers of them act together in parallel.


 * The mysterious aspects of consciousness might disappear, just as the mysterious apects of embryology have largely disappeared now that we know the capabilities of DNA, RNA, and protein.


 * Until we understand what makes us conscious, we are not likely to... design the right sort of artificial machine or to arrive at firm conclusions about consciousness in lower animals.


 * You cannot successfully pursue a difficult problem... without some preconceived ideas to guide you. ...But to a scientist these are only provisional beliefs. He does not have a blind faith in them.


 * The study of consciousness is a scientific problem.


 * Philosophers have had such a poor record over the last two thousand years that they would do better to show a certain modesty rather than the lofty superiority that they usually display.


 * Not only do the beliefs of most popular religions contradict each other but... they are based on evidence so flimsy that only an act of blind faith can make them acceptable.


 * If revealed religions have revealed anything it is that they are usually wrong.


 * I myself find it difficult at times to avoid the idea of a homunculus. ...you cannot be aware of a defect in your brain unless there are neurons whose firing symbolizes that defect. There is no separate "I" who can recognize the defect independent of neural firing.


 * Our [ Christof Koch and I ] ... assumption was that once the visual system is fully understood, the more fascinating aspect of the "soul" will be much easier to study.


 * New knowledge has not diminished our sense of awe but increased it immeasurably.


 * It is unlikely that the Astonishing Hypothesis, if it turns out to be true, will be universally accepted unless it can be presented in such a way that it appeals to people's... need for a coherent view of the world and themselves in terms they can easily understand. It is ironic that while science aims at exactly such a universal view, many people find much of our present scientific understanding too inhuman and too difficult to understand.


 * If the scientific facts... support the Astonishing Hypothesis, then it will be possible to argue that the idea that man has a disembodied soul is as unnecessary as the old idea that there was a Life Force.


 * Our highly developed brains... were not evolved under the pressure of discovering scientific truths but only to enable us to be clever enough to survive and leave descendants.


 * The single most characteristic human ability is that we can handle a complex language fluently. We can use words to denote not only objects and events in the outside world but also more abstract concepts. This ability leads to... our limitless capacity for self-deception. ...without the discipline of scientific research, we shall often jump to wrong conclusions ...

Quotes about The Astonishing Hypothesis

 * "It's all done by nerve cells"—our joys, our sorrows, our memories, our ambitions, our sense of personal identity, and our sense of free will. This is the hypothesis of Francis Crick's latest book. ...So how astonishing is his hypothesis? ...most readers of Perception will find it—apart from the interesting suggestion about the special role of correlated firing—to be much the same as the working hypothesis that they employ daily in the laboratory... the Astonishing Hypothesis is so plausible that it should not be called astonishing"... it is mainly concerned with... the psychology of vision. This is because Crick believes that there is likely to be a basic mechanism for consciousness, similar in different parts of the brain, so it is merely a matter of convenience which area of consciousness one chooses for investigating its neuronal basis.
 * I. M. Glyn, Reviews: "The astonishing hypothesis.." Perception, (1994) Vol. 23. pp. 367-368


 * Crick manages to bring together a great deal of material, and to present it entertainingly, concisely, and yet in a fashion that is easily intelligible to the nonspecialist.
 * I. M. Glyn, Reviews: "The astonishing hypothesis.." Perception, (1994) Vol. 23. pp. 367-368


 * His immediate aim is to persuade us that now is the time to tackle such questions, and he does this by providing plausible hypotheses and suggesting ways in which they might be tested, or describing experiments by others that have a bearing on them. Crick's fertility of suggestion and skill in presenting the essentials of complex experiments make this... excellent reading
 * I. M. Glyn, Reviews: "The astonishing hypothesis.." Perception, (1994) Vol. 23. pp. 367-368


 * If we regard the soul, not as a flappy diaphanous sort of thing that deserts the dying body like a rat leaving a sinking ship, but as whatever it is that enables a conglomeration of the products of some 105 genes to think and feel and love and hate, then the scientific search for the soul is just what Francis Crick's book is about.
 * I. M. Glyn, Reviews: "The astonishing hypothesis.." Perception, (1994) Vol. 23. pp. 367-368


 * It is a fascinating book, even if it is ultimately unpersuasive. ...Trying to work out what the brain is doing by looking at nerve cells is like trying to work out what a poem says by counting the letters in it. ...Crick's 'astonishing hypothesis' is that the mind is just the body... The only problem with this argument is that it seems to leave feelings unexplained. Wouldn't our brains work just the same even if we were zombies... ?
 * David Papineau, Book Review / "Chemistry and an attack of nerves: 'The Astonishing Hypothesis..." The Independent (May 8, 1994)


 * This is a philosophical task, not a scientific one. Unfortunately Crick is no philosopher... It is difficult to take seriously his suggestion that visual awareness may consist of 40-Hertz oscillations in neuronal firing, or that free will is located in the anterior cingulate sulcus. Even so, this book is well worth reading. Crick is an excellent guide to contemporary brain science, and takes his readers deeper than most popular authors.
 * David Papineau, Book Review / "Chemistry and an attack of nerves: 'The Astonishing Hypothesis..." The Independent (May 8, 1994)


 * Richard Gregory, a leading visual psychologist, has argued that Crick is outside of his own field here and could be regarded as a "loose cannon" in the field of visual consciousness, and yet Crick's book is both informative and well written.
 * Bill Webster, "Review of The Astonishing Hypothesis..." The Association for the Scientifice Study of Consciousness (1995)


 * A large part of the book is taken up by reviews of the psychology and the physiology of vision in humans and in primates. These reviews are interesting even though they are slanted towards the hypothesis. ...Overall these reviews are quite interesting—after allowing for Crick's particular point of view.
 * Bill Webster, "Review of The Astonishing Hypothesis..." The Association for the Scientifice Study of Consciousness (1995)


 * There is... no mention of any philosophical opponents of reductionism such as Nagel or McGinn, nor any mention of materialists who take a non-reductive view based on supervenience, rather than the type-type identities of reductionism. I imagine that Crick would tear his hair out if he read McGinn's (1994) argument... that our very cognitive structures will prevent us from ever explaining consciousness.
 * Bill Webster, "Review of The Astonishing Hypothesis..." The Association for the Scientifice Study of Consciousness (1995)