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Sentience: The Invention of Consciousness
The story of a fifty-year quest to uncover the evolutionary history of consciousness from one of the world's leading theoretical psychologists.
We feel, therefore we are. Conscious sensations ground our sense of self. They are crucial to our idea of ourselves as psychic present, existent, and mattering. But is it only humans who feel this way? Do other animals? Will future machines? Weaving together intellectual adventure and cutting-edge science, Nicholas Humphrey describes his fifty-year quest for from his discovery of blindsight in monkeys and his pioneering work on social intelligence to breakthroughs in the philosophy of mind.
The goal is to solve the hard to explain the wondrous, eerie fact of "phenomenal consciousness"--the redness of a poppy, the sweetness of honey, the pain of a bee sting. What does this magical dimension of experience amount to? What is it for? And why has it evolved? Humphrey presents here in full a new, plausible solution that phenomenal consciousness, far from being primitive, is a relatively late and sophisticated evolutionary development. The implications for the existence of sentience in nonhuman animals are startling and provocative.
We feel, therefore we are. Conscious sensations ground our sense of self. They are crucial to our idea of ourselves as psychic present, existent, and mattering. But is it only humans who feel this way? Do other animals? Will future machines? Weaving together intellectual adventure and cutting-edge science, Nicholas Humphrey describes his fifty-year quest for from his discovery of blindsight in monkeys and his pioneering work on social intelligence to breakthroughs in the philosophy of mind.
The goal is to solve the hard to explain the wondrous, eerie fact of "phenomenal consciousness"--the redness of a poppy, the sweetness of honey, the pain of a bee sting. What does this magical dimension of experience amount to? What is it for? And why has it evolved? Humphrey presents here in full a new, plausible solution that phenomenal consciousness, far from being primitive, is a relatively late and sophisticated evolutionary development. The implications for the existence of sentience in nonhuman animals are startling and provocative.
256 pages, Kindle Edition
First published October 27, 2022
144 people are currently reading
3107 people want to read
About the author
Nicholas Humphrey
43 books67 followersNicholas Keynes Humphrey is an English neuropsychologist based in Cambridge, known for his work on evolution of primate intelligence and consciousness. He studied mountain gorillas with Dian Fossey in Rwanda; he was the first to demonstrate the existence of "blindsight" after brain damage in monkeys; he proposed the theory of the "social function of intellect". He is the only scientist to have edited the literary journal Granta.
Humphrey played a significant role in the anti-nuclear movement in the late 1970s and delivered the BBC Bronowski memorial lecture titled "Four Minutes to Midnight" in 1981.
His 10 books include Consciousness Regained, The Inner Eye, A History of the Mind, Leaps of Faith, The Mind Made Flesh, Seeing Red, and Soul Dust. He has received several honours, including the Martin Luther King Memorial Prize, the Pufendorf Medal and the British Psychological Society's book award.
He has been lecturer in psychology at Oxford, assistant director of the Subdepartment of Animal Behaviour at Cambridge, senior research fellow at Cambridge, professor of psychology at the New School for Social Research, New York, and school professor at the London School of Economics.
Humphrey played a significant role in the anti-nuclear movement in the late 1970s and delivered the BBC Bronowski memorial lecture titled "Four Minutes to Midnight" in 1981.
His 10 books include Consciousness Regained, The Inner Eye, A History of the Mind, Leaps of Faith, The Mind Made Flesh, Seeing Red, and Soul Dust. He has received several honours, including the Martin Luther King Memorial Prize, the Pufendorf Medal and the British Psychological Society's book award.
He has been lecturer in psychology at Oxford, assistant director of the Subdepartment of Animal Behaviour at Cambridge, senior research fellow at Cambridge, professor of psychology at the New School for Social Research, New York, and school professor at the London School of Economics.
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Displaying 1 - 30 of 53 reviews
November 21, 2022
The first seventy-odd pages of this book are absolutely phenomenal (pun intended, though still true). We start with a near-stream of consciousness prologue - very appropriate for a book on sentience - and then go on to have a description of the early part of Nicholas Humphrey's career in a wonderfully approachable fashion with a writing style somewhere between a deep conversation and a thought process. I particularly loved Humphrey's description of his heading off to Elba to investigate the paranormal claims of the eccentric Hugh Sartorius Whitaker and his experiences with Dian Fossey (not always pleasant) when visiting to study the 'natural psychologist' ability of gorillas.
The book then takes a change of tack, signified by the author heading the next chapter 'To work', as he sets out to build for us his theory on the nature of sentience and 'phenomenal consciousness'. This too is very interesting, but lacks the same storytelling verve. It's also a lot harder to get your head around, as a lot of the time we are dealing with rather wispy philosophical concepts. The central thesis is that sentience is about not the ability to react to sensations (as it originally meant), but to be consciously aware of what it's like to experience sensations (that's phenomenal consciousness, I think - though I need to say 'I think' because it is difficult to take in).
The job Humphrey has is to persuade the reader of his thesis, apparently not accepted across the board by any means, that sentience arises from a particular mechanism in the brain. This, he suggests, was linked to warm-bloodedness, so it is likely that only mammals and birds (presumably potentially also including earlier dinosaurs) have been sentient - though not all to the same level. He gives a (to me) quite convincing argument that, for example, playing is a good indicator of sentience.
There were times when I think there could have been more explanation (and he might have better avoiding some of the confusing technical terms). So, for example, I don't think there is enough distinction between the sensation of redness as we experience it and the quality of an object being red, which is a simple physical property of giving off photons in a certain range of energies. To philosophers used to discussing this topic, there is a yawning gap between the two - but to the ordinary reader they are much closer and the distinction needed better handling. The same is true of some of the other philosophical niceties that are needed to really get your head around this topic.
Despite this resulting in sometimes feeling like I was experiencing Humphrey's ideas like a view through gauze (going all sensational there), reading this book was a real pleasure.
The book then takes a change of tack, signified by the author heading the next chapter 'To work', as he sets out to build for us his theory on the nature of sentience and 'phenomenal consciousness'. This too is very interesting, but lacks the same storytelling verve. It's also a lot harder to get your head around, as a lot of the time we are dealing with rather wispy philosophical concepts. The central thesis is that sentience is about not the ability to react to sensations (as it originally meant), but to be consciously aware of what it's like to experience sensations (that's phenomenal consciousness, I think - though I need to say 'I think' because it is difficult to take in).
The job Humphrey has is to persuade the reader of his thesis, apparently not accepted across the board by any means, that sentience arises from a particular mechanism in the brain. This, he suggests, was linked to warm-bloodedness, so it is likely that only mammals and birds (presumably potentially also including earlier dinosaurs) have been sentient - though not all to the same level. He gives a (to me) quite convincing argument that, for example, playing is a good indicator of sentience.
There were times when I think there could have been more explanation (and he might have better avoiding some of the confusing technical terms). So, for example, I don't think there is enough distinction between the sensation of redness as we experience it and the quality of an object being red, which is a simple physical property of giving off photons in a certain range of energies. To philosophers used to discussing this topic, there is a yawning gap between the two - but to the ordinary reader they are much closer and the distinction needed better handling. The same is true of some of the other philosophical niceties that are needed to really get your head around this topic.
Despite this resulting in sometimes feeling like I was experiencing Humphrey's ideas like a view through gauze (going all sensational there), reading this book was a real pleasure.
November 25, 2022
Originator of the social intelligence theory of consciousness, philosopher and psychologist, Nicholas Humphrey's books have enthralled and inspired me ever since I saw his The Inner Eye television series in the mid-1980s. Now, eleven years after his last book, comes a new work.
First of all, Sentience is fascinating, beautifully written, thought-provoking and important. But more than that, to my mind it is true. Everything Humphrey writes here, which in some ways sum up his huge contribution to the field of the understanding of consciousness, has that feel of being fundamentally correct. The tale he is telling matches reality.
The book falls into three thirds, the first giving the background to Humphrey’s journey through life and the questions he asked himself as he pondered various unknowns: consciousness… why, and when? This summary is vital for the following two parts, one of which deals with our phenomenal experiences (the redness of a poppy, the sweetness of sugar, etc), and one of which sums it all up in a new perspective, drawing at all times from evolutionary reasoning.
It’s this latter third which I think is groundbreaking. The issue for the vast majority of philosophers dealing with qualia in the brain (that is, how the redness of red can be generated and experienced by “mere” neuron activity) is how to make the leap from neurons to private mental experience. There’s a couple of sentences in this book which I suspect may be the most important Humphrey has ever written. They read: Remember how it emerged in the earlier discussion that when, for example, you project phenomenal redness onto a poppy, you are in effect making a bridge to other sentient beings. You’re seeing the poppy as being ‘rubropotent’ – as having the power to evoke red qualia in another like yourself.
Isn’t that extraordinary? Other philosophers look at one brain in isolation and try to pin down the mind/body relationship therein, but that’s their mistake. Conscious brains, human brains, never exist in isolation. They grow, develop and mature only in social groups. Personally, I think this cultural blind spot has a lot to do with men dominating such intellectual discussions, men who in comparison with women have little grasp of the true importance of relationships.
This, then, is the brilliance of Nicholas Humphrey. He grasps the fundamental role of social relations in the evolution of consciousness. He never loses sight of that evolutionary history, and indeed uses it to underpin the truth of his theory.
As he notes early on in the book, his intellectual and philosophical journey has been rather a lonely furrow. I hope this exceptional work changes all that. It certainly deserves to. It’s more than worthy of being added to his outstanding canon of work. Trailblazing, compelling and true.
First of all, Sentience is fascinating, beautifully written, thought-provoking and important. But more than that, to my mind it is true. Everything Humphrey writes here, which in some ways sum up his huge contribution to the field of the understanding of consciousness, has that feel of being fundamentally correct. The tale he is telling matches reality.
The book falls into three thirds, the first giving the background to Humphrey’s journey through life and the questions he asked himself as he pondered various unknowns: consciousness… why, and when? This summary is vital for the following two parts, one of which deals with our phenomenal experiences (the redness of a poppy, the sweetness of sugar, etc), and one of which sums it all up in a new perspective, drawing at all times from evolutionary reasoning.
It’s this latter third which I think is groundbreaking. The issue for the vast majority of philosophers dealing with qualia in the brain (that is, how the redness of red can be generated and experienced by “mere” neuron activity) is how to make the leap from neurons to private mental experience. There’s a couple of sentences in this book which I suspect may be the most important Humphrey has ever written. They read: Remember how it emerged in the earlier discussion that when, for example, you project phenomenal redness onto a poppy, you are in effect making a bridge to other sentient beings. You’re seeing the poppy as being ‘rubropotent’ – as having the power to evoke red qualia in another like yourself.
Isn’t that extraordinary? Other philosophers look at one brain in isolation and try to pin down the mind/body relationship therein, but that’s their mistake. Conscious brains, human brains, never exist in isolation. They grow, develop and mature only in social groups. Personally, I think this cultural blind spot has a lot to do with men dominating such intellectual discussions, men who in comparison with women have little grasp of the true importance of relationships.
This, then, is the brilliance of Nicholas Humphrey. He grasps the fundamental role of social relations in the evolution of consciousness. He never loses sight of that evolutionary history, and indeed uses it to underpin the truth of his theory.
As he notes early on in the book, his intellectual and philosophical journey has been rather a lonely furrow. I hope this exceptional work changes all that. It certainly deserves to. It’s more than worthy of being added to his outstanding canon of work. Trailblazing, compelling and true.
December 21, 2022
Important advances in the theoretical underpinnings of consciousness. In particular, the solid evolutionary basis gets taken to wonderfully tight conclusions about why consciousness is, how consciousness may work (at only a structural level), what are the conditions for consciousness, and what is and isn’t conscious. In this way it is akin to Schrödinger’s “What is Life” providing the foothold for, and presaging, the discovery of DNA.
What it elides is an explanation of how the subjective magic of consciousness can arise out of matter. His brief description of the structural mechanics defaults to Hofstadter’s “strange loops,” in which stimulus and response feed off recursively. He covers this up with some new words and some fuzzy old words deftly stitched together. But the magic is, still, magic.
The stories of the animal experiences were entertaining, and show how masterful his command of the evidence is. The book is a delight to read - simple, poetic, and clear. To date, the finest exploration of consciousness I’ve read.
What it elides is an explanation of how the subjective magic of consciousness can arise out of matter. His brief description of the structural mechanics defaults to Hofstadter’s “strange loops,” in which stimulus and response feed off recursively. He covers this up with some new words and some fuzzy old words deftly stitched together. But the magic is, still, magic.
The stories of the animal experiences were entertaining, and show how masterful his command of the evidence is. The book is a delight to read - simple, poetic, and clear. To date, the finest exploration of consciousness I’ve read.
March 17, 2024
Interesting stuff despite Humphrey's tendency to dry writing. This latest books of his covers the evolutionary benefits and purpose of sentience, which animals can also be considered sentient beings, and the future relationship of AI and sentience. This last section is a particularly interesting concept given the recent rise of AI technology. The only reason for three stars instead of four is Humphrey's inclusion of his scientific observations over the last several decades. Although necessary to support the theories Humphrey proposes in this book, these observation chapters tend to be quite boring. Still a solid three stars and thought provoking.
June 28, 2025
Nicholas Humphrey's book "Sentience: The Invention of Consciousness" (2022) proposes a functional explanation of consciousness that brings it closer to an evolutionary survival strategy. His central thesis distinguishes between two types of consciousness - cognitive and phenomenological - the latter of which gives colour and texture to the experience of being alive. Humphrey describes consciousness not as a window to the world, but as an internal stage where the organism feels the impact of being in the world. To live, for Humphrey, is to assume more than to exist, it is to feel.
This starting point, which brings consciousness closer to emotion, suggests common ground with authors such as António Damásio (1994), for whom consciousness emerges from the body and the emotions that regulate its homeostasis. However, as the book progresses, Humphrey hesitates to assume this full connection.
Read the full review in Portuguese at Nx: https://narrativax.blogspot.com/2025/...
This starting point, which brings consciousness closer to emotion, suggests common ground with authors such as António Damásio (1994), for whom consciousness emerges from the body and the emotions that regulate its homeostasis. However, as the book progresses, Humphrey hesitates to assume this full connection.
Read the full review in Portuguese at Nx: https://narrativax.blogspot.com/2025/...
October 8, 2023
After many decades of being left at least partially dissatisfied by books about consciousness, I've had a different reaction after reading the new book by Nicholas Humphrey, "Sentience: The Invention of Consciousness". For the first time, I feel that I might understand what consciousness is.
Many previous books left me thinking the ideas in them might offer _part_ of a solution to what phenomenal consciousness is. But my impression is that the ideas in this book are more comprehensive and persuasive.
In short, phenomenal consciousness (which, by the way, needs to be distinguished from cognitive consciousness, which is much less puzzling) is no mere epiphenomenon, and provides a two-fold evolutionary advantage.
First, reflecting on their own internal mental phenomena enables creatures to understand what's likely going on in the minds of other creatures, and therefore enables much richer social interactions.
Second, the same internal reflections provide creatures with a profound sense of their own specialness and importance. They belong to nature but appear to somehow transcend it - which also provides evolutionary advantage.
Humphrey sketches out how phenomenal consciousness might have arisen relatively quickly in evolutionary terms, via fast feedback cycles that took advantage of various previous biological and mental features.
In this way, his theory of consciousness draws on a much wider set of ideas about biology and evolution, compared to the philosophical ideas that other writers have advanced. His own research into the puzzling topic of blindsight is one example.
Humphrey addresses the ideas of many people I've read previously, regarding the role and evolution of consciousness, and his summaries seem to me both fair and persuasive. He is particularly good on the the shortcomings of both panpsychism and IIT.
He advances arguments that phenomenal consciousness is probably restricted to mammals and birds. He realises this will raise hackles and can be viewed as controversial, but he backs up his case with both theoretical considerations and experimental results.
His book closes with considerations about artificial phenomenal consciousness. AIs won't develop these features, Humphrey argues, unless they're explicitly designed in. As for whether this will be a good idea, Humphrey has some interesting points on that subject too.
He describes a number of tests to determine which animals have phenomenal consciousness (and a sense of a continuing self, in themselves and others), and extends these tests in the final section into ways of determining whether an AI is, indeed, phenomenally conscious.
The book adopts a jaunty autobiographical tone, reflecting on his many decades of experience. He uses narrative to build his case carefully, chapter by chapter. Alongside the biological references, there are numerous discursions into poetry and literature. It was a real pleasure!
Many previous books left me thinking the ideas in them might offer _part_ of a solution to what phenomenal consciousness is. But my impression is that the ideas in this book are more comprehensive and persuasive.
In short, phenomenal consciousness (which, by the way, needs to be distinguished from cognitive consciousness, which is much less puzzling) is no mere epiphenomenon, and provides a two-fold evolutionary advantage.
First, reflecting on their own internal mental phenomena enables creatures to understand what's likely going on in the minds of other creatures, and therefore enables much richer social interactions.
Second, the same internal reflections provide creatures with a profound sense of their own specialness and importance. They belong to nature but appear to somehow transcend it - which also provides evolutionary advantage.
Humphrey sketches out how phenomenal consciousness might have arisen relatively quickly in evolutionary terms, via fast feedback cycles that took advantage of various previous biological and mental features.
In this way, his theory of consciousness draws on a much wider set of ideas about biology and evolution, compared to the philosophical ideas that other writers have advanced. His own research into the puzzling topic of blindsight is one example.
Humphrey addresses the ideas of many people I've read previously, regarding the role and evolution of consciousness, and his summaries seem to me both fair and persuasive. He is particularly good on the the shortcomings of both panpsychism and IIT.
He advances arguments that phenomenal consciousness is probably restricted to mammals and birds. He realises this will raise hackles and can be viewed as controversial, but he backs up his case with both theoretical considerations and experimental results.
His book closes with considerations about artificial phenomenal consciousness. AIs won't develop these features, Humphrey argues, unless they're explicitly designed in. As for whether this will be a good idea, Humphrey has some interesting points on that subject too.
He describes a number of tests to determine which animals have phenomenal consciousness (and a sense of a continuing self, in themselves and others), and extends these tests in the final section into ways of determining whether an AI is, indeed, phenomenally conscious.
The book adopts a jaunty autobiographical tone, reflecting on his many decades of experience. He uses narrative to build his case carefully, chapter by chapter. Alongside the biological references, there are numerous discursions into poetry and literature. It was a real pleasure!
February 17, 2024
Are there sentient beings apart from humans? Descartes did not think so, but most people would think there are. In the UK they are making it a law that animals are sentient. The Animal Welfare Bill states that animals are sentient beings capable of feeling pain and pleasure.
Of this Humphrey says it is a philosophical, scientific, ethical and legal mess. (p. xi)
And why stop at animals? Do stones feel? The poet Mary Oliver thinks: “Too terrible it would be, to be wrong.”
Humphrey agrees with the world that stones do not feel, but lobsters and octopuses?
Actually Humphrey thinks that animals are sentient but he restricts that to mammals and birds.
And sentient, of course, in this discussion means conscious. There is a lot of confusion about what consciousness consists in. And I like what I think is what Humphrey thinks when he talks about the phenomenon of blindsight. People with blindsight think they are blind although they are actually capable of seeing. They do not bump into furniture. But they do not experience the seeing. Consciousness is a doubling of the biological function of being aware of something. There is a difference between sensation and perception. (He gives a very good example with the cases of orgasm and position sense. How do you know where your thumb is? How do you know that you have an orgasm? - p. 131)
If this is the case the questions are, a) why has this developed and b) have animals developed such a capability?
Do animals suffer from blindsight? Humphrey thinks they do, or at least one of the monkeys he experimented with is supposed to have had it.
As to the first question:
I agree. If you are attacked instead of fighting back you might create a mental attitude of hatred and the plan to get vengeance later on. (An example of Jaynes.)
Why does he restrict sentience to mammals and birds? Because they are warmblooded. And I must say that he offers some very good reasons for this belief. Being warmblooded is expensive. (A human being must consume thirty times more calories that a boa constrictor.) There are some non-consciousness related advantages but being warmblooded means that the speed of your brain circuits doubles. And this, Humphrey thinks, is vital for developing consciousness.
This sounds very plausible. On the other hand the next phenomenon he introduces makes me stick to my own conviction, namely that consciousness is a cultural asset based on language and restricted to human beings. We are talking about the theory of mind meaning the ability to step inside your fellow being. There is a lot of anecdotical evidence how animals (dogs in particular) are able to do amazing deeds. And Humphrey talks a lot about his dog Ben, but to his credit, he does not do it in a dogmatic way (like Searle for example).
But for some reason he does not talk about young human beings. A three year old is not able to know that if it sees a toy being moved to some other place that another kid not present would not know where the toy now is. A five year kid does know. The five year old kid has mastered language and has in the process developed the idea that people are guided by their selfs and do only know what this self perceives.
Of this Humphrey says it is a philosophical, scientific, ethical and legal mess. (p. xi)
And why stop at animals? Do stones feel? The poet Mary Oliver thinks: “Too terrible it would be, to be wrong.”
Humphrey agrees with the world that stones do not feel, but lobsters and octopuses?
Actually Humphrey thinks that animals are sentient but he restricts that to mammals and birds.
And sentient, of course, in this discussion means conscious. There is a lot of confusion about what consciousness consists in. And I like what I think is what Humphrey thinks when he talks about the phenomenon of blindsight. People with blindsight think they are blind although they are actually capable of seeing. They do not bump into furniture. But they do not experience the seeing. Consciousness is a doubling of the biological function of being aware of something. There is a difference between sensation and perception. (He gives a very good example with the cases of orgasm and position sense. How do you know where your thumb is? How do you know that you have an orgasm? - p. 131)
If this is the case the questions are, a) why has this developed and b) have animals developed such a capability?
Do animals suffer from blindsight? Humphrey thinks they do, or at least one of the monkeys he experimented with is supposed to have had it.
As to the first question:
The short answer is that if being conscious of feeling this way about the situation is to show up in behaviour, it must cause changes in your mental attitudes that dispose you to act in ways you wouldn’t have done otherwise – the mental attitudes being the beliefs, hopes, and so on that you entertain about the situation or about yourself. (p. 90)
I agree. If you are attacked instead of fighting back you might create a mental attitude of hatred and the plan to get vengeance later on. (An example of Jaynes.)
Why does he restrict sentience to mammals and birds? Because they are warmblooded. And I must say that he offers some very good reasons for this belief. Being warmblooded is expensive. (A human being must consume thirty times more calories that a boa constrictor.) There are some non-consciousness related advantages but being warmblooded means that the speed of your brain circuits doubles. And this, Humphrey thinks, is vital for developing consciousness.
This sounds very plausible. On the other hand the next phenomenon he introduces makes me stick to my own conviction, namely that consciousness is a cultural asset based on language and restricted to human beings. We are talking about the theory of mind meaning the ability to step inside your fellow being. There is a lot of anecdotical evidence how animals (dogs in particular) are able to do amazing deeds. And Humphrey talks a lot about his dog Ben, but to his credit, he does not do it in a dogmatic way (like Searle for example).
But for some reason he does not talk about young human beings. A three year old is not able to know that if it sees a toy being moved to some other place that another kid not present would not know where the toy now is. A five year kid does know. The five year old kid has mastered language and has in the process developed the idea that people are guided by their selfs and do only know what this self perceives.
April 10, 2023
Although I have a background in neurology and neuroscience, I was nonetheless a little worried that I wouldn't have the foundation for this book as I am not well-versed in psychology and behavioral sciences. Nonetheless, through a perfect blend of memoir, personal anecdote, and scientific theorizing, the arguments for the foundations and evolutionary development of sentience was well-formed and easy to understand. Distinguishing first between perception and sensation, and frequently harkening back to the concepts encapsulated by the Descartian variation "I feel, therefore I am," the arguments behind the development, evolution, and utility of phenomenological sensation was compellingly argued, as was how this relates to sentence and consciousness, finally ending with what other organisms possess evidence of these behaviors and what implications that has for human interaction. Definitely more than few a-ha moments in this for me, at least. And while there's a part of me that still has a firm foot in the panpsychism argument of consciousness, I can't help but feel equally swayed by this accounting, and what's more it has helped me think about patients with neurological illness that are common in my practice in a new light. Worth the read.
April 2, 2023
Sentience by Nicholas Humphrey was checked out for spouse, who prefers that sort of thing to true crime books about psychotic family annihilators and the like. His review is: best account of animal sentience I have come across.
Highly recommended for those who find the works of Charles Darwin more fascinating than those of Charles Manson.
Highly recommended for those who find the works of Charles Darwin more fascinating than those of Charles Manson.
April 26, 2025
truly niche experience to read about "orgasmic consciousness," including several sentences exploring why it's called "coming," in the fourth floor of building 2 as around me, dozens of mathematicians held deeply sexless conversations at an "informal analysis seminar." or at least i hope they were deeply sexless. i really hope.
December 13, 2024
Sensations have a qualitative dimension that sets them apart from all other mental states. There's something our pains, smells, sights have in common that our thoughts, beliefs, wishes don't.
When we experience qualia, *it's like something* to have the experience.
A creature is sentient only if it consciously experiences qualia - it becomes like something to be itself.
A state is CONSCIOUS when its contents are available to a *global workspace* in the brain.
Consciousness is not restricted to states that have phenomenal quality.
Consciousness means having knowledge of what's in your mind. Conscious mental states comprise of states to which at any one time you have introspective access and which you are the subject. Some of these states: memories, emotions, wishes, thoughts, feelings. Wherever your self focuses gaze, it takes over as singular subject - only one You. Anything in consciousness becomes sharable with whatever else is (singular unity is not a logical necessity)
Feeling the p quality of sensations is not necessary for consciousness. Lacking this, creatures can still introspect, know their own minds, have self-narratives, be highly intelligent, goal-directed, motivated, percipient. Yet if it could not experience sensory qualia, it would not be sentient.
-
BLINDSIGHT
Helen - monkey: removed visual cortex
after operation, gave up use of her eyes.
H(Humphrey)meets Helen & tries to teach her to see.
Before long Helen was reaching out to touch things he offered.
Primatologist visits Helen & takes her out of her cage & takes her for walks.
Helen at first bumped into obstacles & fell. Over next few weeks she began to anticipate & move around objects.
Eventually she could single out a tree, go over to it, climb it.
Eventually she would reach out if a target was within arm's reach but ignore it if it was too far away.
Developing 3-d visual perception that she could monitor introspectively.
To anyone unaware of her blindness she would seem normal.
Despite evidence, H did not think Helen *expected* to be able to see. Seemed unsure of herself. If she was upset or frightened her confidence would desert her & she would behave as if blind again.
"It was as if Helen could only use her vision when she was relaxed enough not to think about it."
D.B.- human: removed visual cortex on right-hand side of his brain
Immediate loss of vision in the left half of visual field
When asked to *guess* where a light may be, he consistently got it right. Could guess position, shape, color, yet the whole time be unaware of any visual sensation.
Human 2: no visual cortex
considered himself totally blind
could walk down a cluttered corridor & avoid everything
Helen's vision - mediated by SUPERIOR COLLICULUS, evolutionary descendant of the frog's optic tectum.
Blindsight: person has a form of visual perception but none of the usual sensations that would normally tell him about the light at eye. As far as they're concerned, they can only 'guess.' The patient is no longer aware of having grounds for perception: it has nothing to do with *them*
Blindsight - pure perception in the absence of sensation.
Should be consciously accessible, though the subject may be confused because the phenomenal dimension is missing
Found w several patients that even though they maintain they don't see stimulus, they are 'aware' in a vague way of what's out there - called type-2 blindsight.
H.D.- human: age 3 got smallpox which scarred corneas & left her blind.
27: cornea graft operation. Technical success, but her vision didn't improve & she displayed blindness symptoms.
Visual cortex had degenerated from lack of use. Blindsight like Helen: new eyes aren't needed, a new brain is.
Taking H.D. around London & teaching her to ‘see’ again, like Helen: SOMETHING had changed from before the operation: She could point to pigeons, reach for flowers, step up when she comes to curbs - use eyes to guide through space: Her eyes & brain were working together.
She herself remained unhappy: Her vision lacked any subjective sensory quality. She always heard how great vision is, but once she could ‘see’ she couldn't feel any benefits.
"lacking phenomenal quality, she didn't experience it as *hers*: indeed, it didn't contribute to her sense of *self*. She felt cheated. It was a mockery of what she had imagined."
H.D. refused testing & lost interest in seeing, became depressed & almost suicidal. Went back to behaving conventionally blind and got more control of her life again.
"When visual perception exists in the absence of visual sensation, the experience of seeing doesn't bring with it a feeling of subjective presence."
-
Humans make choices governed by the quality of their sensations.
10/10 monkeys showed same strong pattern of preference
H thought this indicated the monkey's subjective feelings about the color at their eyes.
H reasoned that monkeys preferred blue over red because they liked the sensation of blue light more than red.
Alternative:
Woodlouse in box with damp end & dry end: longer time in damp end.
Reason: it walks faster when it senses dryness in the air, so will probably exit the dry end sooner.
No reason to think the woodlouse likes being damp more than dry.
H’s new monkey experiment:
Instead of having the light color change when the monkey let go of a button & pressed again, have it stay the same.
Monkeys continued switching light on & off even when the color didn't change, but the hold times were shorter in red.
H’s earlier interpretation was wrong: it had to do with timing, not liking.
Exp 3: red room & blue room: monkeys go back & form but wait longer in blue. If both were blue or both were red, they would still keep moving but still wait longer in blue.
Both sides red or blue: 10 sec bouts, 50% in blue; 30% in red. 30 sec bouts, 10% blue, 3% red.
Displays a Poisson distribution: the probability the monkey will decide to move in the immediate future remains the same no matter how long she's already been sitting.
Example: monkey tosses coin every H sec: if heads, he moves; if tails, he stays. H sec later tosses coin again. The shorter H is (the more frequent he flips) the sooner he is to get heads and move.
The decision to move was coming more rapidly in red light than blue with the monkeys (50% more rapidly).
Every monkey tested showed the same response: hardwired trait: survival value for monkeys in the wild.
To you, the experimenter, nothing is to be learned from moving. Yet how could the monkeys be sure?
Look at a Necker Cube.
You know nothing is going to change, yet you see it this way & that way & this way again. You sample the alternatives, just in case. Prob like that for the monkeys. Every so often the urge to check if something is missing comes over them.
Periodic checks are adaptive. Unlike a testing box, real world cannot be counted on to remain stable.
Mustn't be too obsessive or nonchalant though.
Sky/red & sky/blue are real situations to wild monkeys that have their own unique dangers and benefits.
-
Sensations motivate us what to think & do & say.
"’Uncle Bert [a silverback gorilla] charged me, but came to a stop just a few feet away, with an embarrassed look on his face.’ Hinde had scrawled across this, ‘How many times have I told you, you really must not use this kind of language.’ But, she protested to me, it's the truth, he did have an embarrassed look."
INTROSPECTIVE CONSCIOUSNESS - Above brain power, natural psychologist needs a brain story. Consciousness helps provide this: user-friendly narrative about experience.
Mind-reading involves self-knowledge. We construct other minds in the image of our own.
Two representations:
Sensation: tracking the nature of stimulation at body surface & how it's affecting you (the sweetness on YOUR tongue)
Perceptions: tracking objects in the external world.
Sensation: body-centered, evaluative, & personal, in contrast to perception. You read your own responses to sensory stimulation to get a mental picture.
You describe sensory experiences in terms of phenomenal qualities (redness, painfulness, sweetness) that have no counterpart in physical reality; they are your *idea* of what it feels like to have this happening to you; they can have whatever properties evolutionarily appropriate to describing this subjective state.
It's common but false to believe properties you ascribe to personal sensations inhere in external objects you perceive. Perception & sensation are often conjoined in our experiences so we confound their different attributes.
-
See red: no activity OF the brain that IS phenomenally red: there is activity BY the brain that CREATES THE IDEA of p redness.
We should be looking for the neural correlates of REPRESENTING consciousness, not the neural correlates of consciousness.
2-stage process: brain activity that is the VEHICLE for the representation, & activity that takes this vehicle to POINT to the idea. No reason to expect either process to have phenomenal properties in its own right.
The p quality of sensations is neither necessary or relevant to judgements or good or bad. Burning hand on stove & withdrawing doesn't require p dimension; the phenomenality we experience has been added in evolution.
-
Hydrancephaly - no cerebral hemispheres are absent
H children show emotions & excitement & reaction
Solms: It does feel like something to be these children; they are phenomenally conscious.
H: Opposite conclusion: They are representing what's happening to them as good/bad, but in absence of higher brain centers these representations lack p properties; it's not like something to be these children
-
Complex lives: reflex behavior is not enough.
Evolve: way of representing & holding in mind info.
Sensation: an inside observer could know how you're feeling from what you're doing: monitor your own responses.
"...for humans - sensations have evolved to be a metaphysical supplement to the reality of our embodiment. To put it at its grandest: we have a phenomenal self in order not to die of materialism."
Distinctness to sensory modalities (a color isnt a sound or smell): Groupings that reflect deep structure of natural world?
No: no distinct kinds found in environment or physiology of brain. Receptors in different sense organs have evolved from a single hair-like cell, the sensory CILIUM, & respond the same electromagnetically. Looking at nerve cells in brain you couldn't tell from the pattern whether the cell was signalling light or sound or touch info.
Mind-reading - phenomenal experience helps imagine what it's like to be another: you narrow range or behaviors to expect.
Qualia-coding introduces a diff in sensory information gathered from the environment that exists in a continuum. Your mind takes artistic licence w how it represents what's going on in your brain.
Qualia-coding is ‘a lie that helps you realize truth’.
"Sensations originated as evaluative responses to sensory stimulation, a form of bodily expression that the subject reads to get a picture of what's happening. When this response is privatized, it creates the potential for feedback loops that can be elaborated to create the complex attractors that underwrite phenomenal experience. But note how this particular *history* is crucial. It's precisely because sensations originated in bodily expression that they could go on to acquire phenomenal properties; & it's because other mental states did not originate this way that they could not."
PROPRIOCEPTION - Position sense - uses info picked up by sensors in joints & muscles to enable you to perceive spatial location of your body parts: where your thumb is located in space. In the dark, you still perceive where thumb is.
Visual perception can relay the same fact in light. What's different about position sense: no accompanying sensation like vision or hearing. Brain is using info passed by proprioceptors but not providing you w representation of stimuli. No sensation, no phenomenal dimension & no modality-specific quality: there nothing it's *like* in the dark for you to have your thumb located where it is.
Position sense is a lot like blindsight.
Where is your thumb?
Sentition - evaluative motor response to sensory stimulation
Sensation - monitor this response & make mental representation
Phenomenal Sensation - feedback loops established
Sensitives - respond to sensory stim but don't make mental representation (sea anemones, starfish, earthworms, slugs)
Sub-sentients - possess cognitive consciousness, can even form complex societies, but limited sense of individuality. Form mental rep of sensory stim but sensations lack p dimension (honeybees, octopus, goldfish, frogs)
Sentients - phenomenal depth (mammals, birds)
-
Mammals & birds are WARM-BLOODED
Warm-bloodedness played double role in sentience evolution: changes in lifestyle that made sentience an asset, & prepared the brain to deliver it.
Evolved independently in dinosaurs (bird ancestors) & cynodonts (mammal anc) around the same time (200 mya) during major climatic upheavals.
Big energy expenditure: humans must eat 50x more frequent than boa constrictor of same size & consume 30x more cal overall.
Advantages: As temp goes up various body processes become more energetically efficient: Cost of sending an impulse along a nerve decreases until it reaches a minimum at 37°C, meaning even though the overall cost for running body goes up w being warm-blooded, brain costs are reduced. Mammals & birds can support larger & complex brains w relative little extra energy outlay.
Provides a defence against fungi & bacteria infection. Cold-blooded animals are plagued by fungal infections. Few parasitic fungi can survive about 37°
Allows animals to ride out climatic changes & expand geographic range. C-blooded animals are limited in range; w-blooded take their environment with them. Many c-blooded species became extinct at the time w-b evolved.
Evolutionary change in the brain conductive to establishing feedback loops that create ipsundrum: increase in conduction speed of nerve cells, decrease in refractory period following nerve cells firing.
Neurons change with temperature.
Increasing temperature in the brain has both these effects.
Speed of brain circuits more than doubled in ancestors that transitioned to warm-blooded.
-
Experiences are valued irrespective of whether they make life better or worse.
Music is first and foremost about sensation: It's good to be there as the subject.
Masturbation is widespread in mammals & birds.
Orgasm has long played a part in the birth and sustenance of the self.
Dogs will signal to humans they want food that is out of their reach by looking back & forth from person to food.
Dogs will still do this if they have every reason to believe the person is blind.
Guide dogs don't understand their owners' different attentional state, do not detect their owners can't see them. Will smack their lips loudly to provide a non visual cue, but don't do this instead of.
Dogs are over-reliant on using themselves as models. Cannot think outside the box of their own experience. Blindness too weird to grasp.
Rats rescue other rats & if they know what it's like they are moved more quickly to action. Cruel experiment with rhesus monkeys - they'll refuse to shock their friend even if it means going hungry.
Natural psychologists are ill prepared to handle oblivion.
Non-human animals often don't seem to understand the meaning of death.
Humans have little better understanding of death but in one way are much better informed: passing on knowledge.
Afterlife: Widely held belief.
Successful meme: It's COMMON SENSE: Your self never goes away & always is conserved. When it detaches from our body on earth, it must exist disembodied somewhere.
COMFROTING: self matters most of all. You won't cease to matter just because you're dead
IRREFUTABLE: nothing can prove it's wrong. & with all the stories of prayers answered, spirits, ghosts, it must exist.
Antidote to existential despair & incentive to conduct yourself commendably.
Selective advantage to whatever psychological traits makes afterlife belief stick.
Humans 100k yrs ago: sensual, sapient, self-esteem, theory of mind, compassion, linguistic culture threshold, ideas of soul, death, survival.
Underlying all this: phenomenal self, created by bodily sensations.
Make the self more remarkable: promoted by natural selection.
-
"People often now talk about octopuses as ‘smart’, & in some ways they are. But that is not the term that comes readily to my mind… Octopuses are exploratory animals who direct the complexity of their bodies on whatever confronts them. They fiddle about & try things & turn the problem over & over - physically, not mentally…They are not, for the most part, ruminative & ‘clever’ sorts of animals." - Peter Godfrey-Smith
Also P G-Smith: octopus are playful, social, psychologically astute.
H: are they? Nothing to suggest they seek out sensory experience to enlarge what they know about their own capacity for feeling rather than knowledge of outside world. No evidence octopus collaborate or form intimate relationships.
No evidence of an octopus understanding what it's like to be another octopus. They aren't qualiaphiliacs or natural psychologists or know or care about selves.
Behavior that gives H pause: octopus carrying tools/shells which indicates future planning with a self in mind.
"...Does [Smith] mean they are cognitively conscious (which I'd say is quite plausible) or phenomenally conscious (which, on the evidence, is quite implausible)?
...he fails to make this distinction & lines up with those theorists who regard phenomenal consciousness as something that simply pops into existence in a complex brain - an intrinsic property *of* brain activity rather than a property of sensations as represented*by* the brain. Indeed, he derides the very idea of qualia as representations. ‘Qualia are not extra things that need an explanation, somehow produced by the workings of the physical system. Instead they are part of what it is to be the system.’ To my mind, this explains nothing at all."
-
P consciousness can't establish itself unbidden, as a corollary of high int or complex info processing.
Late addition to animals, requires dedicated circuitry, selected because of effects on psychology.
Schneider & Turner: AI Consciousness Test: Indication of consciousness: adults quickly & readily grasp concepts based on the quality of felt consciousness - minds switching & leaving bodies, life after death/reincarnation. Reality or no, difficult to comprehend for entity w/o conscious experience.
H: good, but add emphasis to the sensory dimension of phenomenal consciousness & inquire if robot shows qualiaphilia: if it *likes* being conscious & would go out of its way to listen to music. Consider how robot would take advantage of p self: empathy & mind-reading.
Robot's p self won't be secondary feature, it'll have to be the very reason for wanting to build a sentient machine to start with.
Future humans: Research the evolution of sentience & deem the role the P self plays in self-esteem & deepening social relationships important.
Robots become integrated in lives of humans & other robots. Natural psychologists are the ‘fittest’. Robot-to-robot intersubjectivity becomes important once they are living in autonomous r colonies. We want to establish self-perpetuating colonies on other planets & in space. Need to be scientifically imaginative & philosophically reflective. Danger: robot missionaries succumbing to existential despair. Belief in afterlife becomes adaptive for robots. Praise robo Jesus.
When we experience qualia, *it's like something* to have the experience.
A creature is sentient only if it consciously experiences qualia - it becomes like something to be itself.
A state is CONSCIOUS when its contents are available to a *global workspace* in the brain.
Consciousness is not restricted to states that have phenomenal quality.
Consciousness means having knowledge of what's in your mind. Conscious mental states comprise of states to which at any one time you have introspective access and which you are the subject. Some of these states: memories, emotions, wishes, thoughts, feelings. Wherever your self focuses gaze, it takes over as singular subject - only one You. Anything in consciousness becomes sharable with whatever else is (singular unity is not a logical necessity)
Feeling the p quality of sensations is not necessary for consciousness. Lacking this, creatures can still introspect, know their own minds, have self-narratives, be highly intelligent, goal-directed, motivated, percipient. Yet if it could not experience sensory qualia, it would not be sentient.
-
BLINDSIGHT
Helen - monkey: removed visual cortex
after operation, gave up use of her eyes.
H(Humphrey)meets Helen & tries to teach her to see.
Before long Helen was reaching out to touch things he offered.
Primatologist visits Helen & takes her out of her cage & takes her for walks.
Helen at first bumped into obstacles & fell. Over next few weeks she began to anticipate & move around objects.
Eventually she could single out a tree, go over to it, climb it.
Eventually she would reach out if a target was within arm's reach but ignore it if it was too far away.
Developing 3-d visual perception that she could monitor introspectively.
To anyone unaware of her blindness she would seem normal.
Despite evidence, H did not think Helen *expected* to be able to see. Seemed unsure of herself. If she was upset or frightened her confidence would desert her & she would behave as if blind again.
"It was as if Helen could only use her vision when she was relaxed enough not to think about it."
D.B.- human: removed visual cortex on right-hand side of his brain
Immediate loss of vision in the left half of visual field
When asked to *guess* where a light may be, he consistently got it right. Could guess position, shape, color, yet the whole time be unaware of any visual sensation.
Human 2: no visual cortex
considered himself totally blind
could walk down a cluttered corridor & avoid everything
Helen's vision - mediated by SUPERIOR COLLICULUS, evolutionary descendant of the frog's optic tectum.
Blindsight: person has a form of visual perception but none of the usual sensations that would normally tell him about the light at eye. As far as they're concerned, they can only 'guess.' The patient is no longer aware of having grounds for perception: it has nothing to do with *them*
Blindsight - pure perception in the absence of sensation.
Should be consciously accessible, though the subject may be confused because the phenomenal dimension is missing
Found w several patients that even though they maintain they don't see stimulus, they are 'aware' in a vague way of what's out there - called type-2 blindsight.
H.D.- human: age 3 got smallpox which scarred corneas & left her blind.
27: cornea graft operation. Technical success, but her vision didn't improve & she displayed blindness symptoms.
Visual cortex had degenerated from lack of use. Blindsight like Helen: new eyes aren't needed, a new brain is.
Taking H.D. around London & teaching her to ‘see’ again, like Helen: SOMETHING had changed from before the operation: She could point to pigeons, reach for flowers, step up when she comes to curbs - use eyes to guide through space: Her eyes & brain were working together.
She herself remained unhappy: Her vision lacked any subjective sensory quality. She always heard how great vision is, but once she could ‘see’ she couldn't feel any benefits.
"lacking phenomenal quality, she didn't experience it as *hers*: indeed, it didn't contribute to her sense of *self*. She felt cheated. It was a mockery of what she had imagined."
H.D. refused testing & lost interest in seeing, became depressed & almost suicidal. Went back to behaving conventionally blind and got more control of her life again.
"When visual perception exists in the absence of visual sensation, the experience of seeing doesn't bring with it a feeling of subjective presence."
-
Humans make choices governed by the quality of their sensations.
10/10 monkeys showed same strong pattern of preference
H thought this indicated the monkey's subjective feelings about the color at their eyes.
H reasoned that monkeys preferred blue over red because they liked the sensation of blue light more than red.
Alternative:
Woodlouse in box with damp end & dry end: longer time in damp end.
Reason: it walks faster when it senses dryness in the air, so will probably exit the dry end sooner.
No reason to think the woodlouse likes being damp more than dry.
H’s new monkey experiment:
Instead of having the light color change when the monkey let go of a button & pressed again, have it stay the same.
Monkeys continued switching light on & off even when the color didn't change, but the hold times were shorter in red.
H’s earlier interpretation was wrong: it had to do with timing, not liking.
Exp 3: red room & blue room: monkeys go back & form but wait longer in blue. If both were blue or both were red, they would still keep moving but still wait longer in blue.
Both sides red or blue: 10 sec bouts, 50% in blue; 30% in red. 30 sec bouts, 10% blue, 3% red.
Displays a Poisson distribution: the probability the monkey will decide to move in the immediate future remains the same no matter how long she's already been sitting.
Example: monkey tosses coin every H sec: if heads, he moves; if tails, he stays. H sec later tosses coin again. The shorter H is (the more frequent he flips) the sooner he is to get heads and move.
The decision to move was coming more rapidly in red light than blue with the monkeys (50% more rapidly).
Every monkey tested showed the same response: hardwired trait: survival value for monkeys in the wild.
To you, the experimenter, nothing is to be learned from moving. Yet how could the monkeys be sure?
Look at a Necker Cube.
You know nothing is going to change, yet you see it this way & that way & this way again. You sample the alternatives, just in case. Prob like that for the monkeys. Every so often the urge to check if something is missing comes over them.
Periodic checks are adaptive. Unlike a testing box, real world cannot be counted on to remain stable.
Mustn't be too obsessive or nonchalant though.
Sky/red & sky/blue are real situations to wild monkeys that have their own unique dangers and benefits.
-
Sensations motivate us what to think & do & say.
"’Uncle Bert [a silverback gorilla] charged me, but came to a stop just a few feet away, with an embarrassed look on his face.’ Hinde had scrawled across this, ‘How many times have I told you, you really must not use this kind of language.’ But, she protested to me, it's the truth, he did have an embarrassed look."
INTROSPECTIVE CONSCIOUSNESS - Above brain power, natural psychologist needs a brain story. Consciousness helps provide this: user-friendly narrative about experience.
Mind-reading involves self-knowledge. We construct other minds in the image of our own.
Two representations:
Sensation: tracking the nature of stimulation at body surface & how it's affecting you (the sweetness on YOUR tongue)
Perceptions: tracking objects in the external world.
Sensation: body-centered, evaluative, & personal, in contrast to perception. You read your own responses to sensory stimulation to get a mental picture.
You describe sensory experiences in terms of phenomenal qualities (redness, painfulness, sweetness) that have no counterpart in physical reality; they are your *idea* of what it feels like to have this happening to you; they can have whatever properties evolutionarily appropriate to describing this subjective state.
It's common but false to believe properties you ascribe to personal sensations inhere in external objects you perceive. Perception & sensation are often conjoined in our experiences so we confound their different attributes.
-
See red: no activity OF the brain that IS phenomenally red: there is activity BY the brain that CREATES THE IDEA of p redness.
We should be looking for the neural correlates of REPRESENTING consciousness, not the neural correlates of consciousness.
2-stage process: brain activity that is the VEHICLE for the representation, & activity that takes this vehicle to POINT to the idea. No reason to expect either process to have phenomenal properties in its own right.
The p quality of sensations is neither necessary or relevant to judgements or good or bad. Burning hand on stove & withdrawing doesn't require p dimension; the phenomenality we experience has been added in evolution.
-
Hydrancephaly - no cerebral hemispheres are absent
H children show emotions & excitement & reaction
Solms: It does feel like something to be these children; they are phenomenally conscious.
H: Opposite conclusion: They are representing what's happening to them as good/bad, but in absence of higher brain centers these representations lack p properties; it's not like something to be these children
-
Complex lives: reflex behavior is not enough.
Evolve: way of representing & holding in mind info.
Sensation: an inside observer could know how you're feeling from what you're doing: monitor your own responses.
"...for humans - sensations have evolved to be a metaphysical supplement to the reality of our embodiment. To put it at its grandest: we have a phenomenal self in order not to die of materialism."
Distinctness to sensory modalities (a color isnt a sound or smell): Groupings that reflect deep structure of natural world?
No: no distinct kinds found in environment or physiology of brain. Receptors in different sense organs have evolved from a single hair-like cell, the sensory CILIUM, & respond the same electromagnetically. Looking at nerve cells in brain you couldn't tell from the pattern whether the cell was signalling light or sound or touch info.
Mind-reading - phenomenal experience helps imagine what it's like to be another: you narrow range or behaviors to expect.
Qualia-coding introduces a diff in sensory information gathered from the environment that exists in a continuum. Your mind takes artistic licence w how it represents what's going on in your brain.
Qualia-coding is ‘a lie that helps you realize truth’.
"Sensations originated as evaluative responses to sensory stimulation, a form of bodily expression that the subject reads to get a picture of what's happening. When this response is privatized, it creates the potential for feedback loops that can be elaborated to create the complex attractors that underwrite phenomenal experience. But note how this particular *history* is crucial. It's precisely because sensations originated in bodily expression that they could go on to acquire phenomenal properties; & it's because other mental states did not originate this way that they could not."
PROPRIOCEPTION - Position sense - uses info picked up by sensors in joints & muscles to enable you to perceive spatial location of your body parts: where your thumb is located in space. In the dark, you still perceive where thumb is.
Visual perception can relay the same fact in light. What's different about position sense: no accompanying sensation like vision or hearing. Brain is using info passed by proprioceptors but not providing you w representation of stimuli. No sensation, no phenomenal dimension & no modality-specific quality: there nothing it's *like* in the dark for you to have your thumb located where it is.
Position sense is a lot like blindsight.
Where is your thumb?
Sentition - evaluative motor response to sensory stimulation
Sensation - monitor this response & make mental representation
Phenomenal Sensation - feedback loops established
Sensitives - respond to sensory stim but don't make mental representation (sea anemones, starfish, earthworms, slugs)
Sub-sentients - possess cognitive consciousness, can even form complex societies, but limited sense of individuality. Form mental rep of sensory stim but sensations lack p dimension (honeybees, octopus, goldfish, frogs)
Sentients - phenomenal depth (mammals, birds)
-
Mammals & birds are WARM-BLOODED
Warm-bloodedness played double role in sentience evolution: changes in lifestyle that made sentience an asset, & prepared the brain to deliver it.
Evolved independently in dinosaurs (bird ancestors) & cynodonts (mammal anc) around the same time (200 mya) during major climatic upheavals.
Big energy expenditure: humans must eat 50x more frequent than boa constrictor of same size & consume 30x more cal overall.
Advantages: As temp goes up various body processes become more energetically efficient: Cost of sending an impulse along a nerve decreases until it reaches a minimum at 37°C, meaning even though the overall cost for running body goes up w being warm-blooded, brain costs are reduced. Mammals & birds can support larger & complex brains w relative little extra energy outlay.
Provides a defence against fungi & bacteria infection. Cold-blooded animals are plagued by fungal infections. Few parasitic fungi can survive about 37°
Allows animals to ride out climatic changes & expand geographic range. C-blooded animals are limited in range; w-blooded take their environment with them. Many c-blooded species became extinct at the time w-b evolved.
Evolutionary change in the brain conductive to establishing feedback loops that create ipsundrum: increase in conduction speed of nerve cells, decrease in refractory period following nerve cells firing.
Neurons change with temperature.
Increasing temperature in the brain has both these effects.
Speed of brain circuits more than doubled in ancestors that transitioned to warm-blooded.
-
Experiences are valued irrespective of whether they make life better or worse.
Music is first and foremost about sensation: It's good to be there as the subject.
Masturbation is widespread in mammals & birds.
Orgasm has long played a part in the birth and sustenance of the self.
Dogs will signal to humans they want food that is out of their reach by looking back & forth from person to food.
Dogs will still do this if they have every reason to believe the person is blind.
Guide dogs don't understand their owners' different attentional state, do not detect their owners can't see them. Will smack their lips loudly to provide a non visual cue, but don't do this instead of.
Dogs are over-reliant on using themselves as models. Cannot think outside the box of their own experience. Blindness too weird to grasp.
Rats rescue other rats & if they know what it's like they are moved more quickly to action. Cruel experiment with rhesus monkeys - they'll refuse to shock their friend even if it means going hungry.
Natural psychologists are ill prepared to handle oblivion.
Non-human animals often don't seem to understand the meaning of death.
Humans have little better understanding of death but in one way are much better informed: passing on knowledge.
Afterlife: Widely held belief.
Successful meme: It's COMMON SENSE: Your self never goes away & always is conserved. When it detaches from our body on earth, it must exist disembodied somewhere.
COMFROTING: self matters most of all. You won't cease to matter just because you're dead
IRREFUTABLE: nothing can prove it's wrong. & with all the stories of prayers answered, spirits, ghosts, it must exist.
Antidote to existential despair & incentive to conduct yourself commendably.
Selective advantage to whatever psychological traits makes afterlife belief stick.
Humans 100k yrs ago: sensual, sapient, self-esteem, theory of mind, compassion, linguistic culture threshold, ideas of soul, death, survival.
Underlying all this: phenomenal self, created by bodily sensations.
Make the self more remarkable: promoted by natural selection.
-
"People often now talk about octopuses as ‘smart’, & in some ways they are. But that is not the term that comes readily to my mind… Octopuses are exploratory animals who direct the complexity of their bodies on whatever confronts them. They fiddle about & try things & turn the problem over & over - physically, not mentally…They are not, for the most part, ruminative & ‘clever’ sorts of animals." - Peter Godfrey-Smith
Also P G-Smith: octopus are playful, social, psychologically astute.
H: are they? Nothing to suggest they seek out sensory experience to enlarge what they know about their own capacity for feeling rather than knowledge of outside world. No evidence octopus collaborate or form intimate relationships.
No evidence of an octopus understanding what it's like to be another octopus. They aren't qualiaphiliacs or natural psychologists or know or care about selves.
Behavior that gives H pause: octopus carrying tools/shells which indicates future planning with a self in mind.
"...Does [Smith] mean they are cognitively conscious (which I'd say is quite plausible) or phenomenally conscious (which, on the evidence, is quite implausible)?
...he fails to make this distinction & lines up with those theorists who regard phenomenal consciousness as something that simply pops into existence in a complex brain - an intrinsic property *of* brain activity rather than a property of sensations as represented*by* the brain. Indeed, he derides the very idea of qualia as representations. ‘Qualia are not extra things that need an explanation, somehow produced by the workings of the physical system. Instead they are part of what it is to be the system.’ To my mind, this explains nothing at all."
-
P consciousness can't establish itself unbidden, as a corollary of high int or complex info processing.
Late addition to animals, requires dedicated circuitry, selected because of effects on psychology.
Schneider & Turner: AI Consciousness Test: Indication of consciousness: adults quickly & readily grasp concepts based on the quality of felt consciousness - minds switching & leaving bodies, life after death/reincarnation. Reality or no, difficult to comprehend for entity w/o conscious experience.
H: good, but add emphasis to the sensory dimension of phenomenal consciousness & inquire if robot shows qualiaphilia: if it *likes* being conscious & would go out of its way to listen to music. Consider how robot would take advantage of p self: empathy & mind-reading.
Robot's p self won't be secondary feature, it'll have to be the very reason for wanting to build a sentient machine to start with.
Future humans: Research the evolution of sentience & deem the role the P self plays in self-esteem & deepening social relationships important.
Robots become integrated in lives of humans & other robots. Natural psychologists are the ‘fittest’. Robot-to-robot intersubjectivity becomes important once they are living in autonomous r colonies. We want to establish self-perpetuating colonies on other planets & in space. Need to be scientifically imaginative & philosophically reflective. Danger: robot missionaries succumbing to existential despair. Belief in afterlife becomes adaptive for robots. Praise robo Jesus.
September 3, 2024
This volume started strong and abruptly veered off into something decidedly less so. Humphrey has clearly been thinking about issues in consciousness for a long time, but I found his approach here to be both befuddling and unconvincing. His concept of the "ipsundrum" (which seems to just be a recursive feedback loop that increases phenomenality once it's established) is not well described, seems to beg the question, and forms the basis for a lot of later theorizing. It's a pretty poor answer standing on its own, but I agree that self-referentiality seems like an inherent feature of consciousness that could "thicken" it over time... but the phase-shift into it remains frustratingly vague in this account. I guess if you apply a little handwaving, phenomenal consciousness bootstraps itself? Ipsundrum might as well be unobtanium. Nothing in Humphrey's distinction between phenomenal consciousness and cognitive consciousness, while helpful, really explains the tipping point of suddenly having the phenomenal experience of qualia.
Even though I remained unconvinced, I did find his positions bold and interesting to consider. Specifically, his argument that only certain animals possess phenomenal consciousness was provocative. He argues there was a distinct binary shift, not a spectrum of consciousness, and goes on to put only birds and mammals on the phenomenal side of the divide. On what basis? None really, except that warm-blooded brains are more efficient and faster. Maybe, but how could you possibly extrapolate from this to the interiority of a slower arthropod brain, etc.? Humphrey's position feels like an article of faith, not an argument. I appreciate that Humphrey values his dog's consciousness based on all the super cute stuff he does, but he hardly convinced me that a snake has the lights off inside just because it's less anthropomorphic.
Even though Humphrey persuaded me of little, I did enjoy reading the perspective of one of Dennett's allies (even though Humphrey also tries to establish a little daylight between them) and his resistance to panpsychism or Chalmers' framing of the hard problem of consciousness. It's helpful to understand other perspectives on these intractable problems. While this book didn't change my mind on pretty much any aspect of theories of mind, I valued his intellectual consistency. Humphrey is from the "wrong and interesting" school of thought, in my estimation, but at least that avoids the boring. I also loved his concept of "qualiaphilia" and the natural desire our kinds of brains have for experiences of phenomenal depth.
Even though I remained unconvinced, I did find his positions bold and interesting to consider. Specifically, his argument that only certain animals possess phenomenal consciousness was provocative. He argues there was a distinct binary shift, not a spectrum of consciousness, and goes on to put only birds and mammals on the phenomenal side of the divide. On what basis? None really, except that warm-blooded brains are more efficient and faster. Maybe, but how could you possibly extrapolate from this to the interiority of a slower arthropod brain, etc.? Humphrey's position feels like an article of faith, not an argument. I appreciate that Humphrey values his dog's consciousness based on all the super cute stuff he does, but he hardly convinced me that a snake has the lights off inside just because it's less anthropomorphic.
Even though Humphrey persuaded me of little, I did enjoy reading the perspective of one of Dennett's allies (even though Humphrey also tries to establish a little daylight between them) and his resistance to panpsychism or Chalmers' framing of the hard problem of consciousness. It's helpful to understand other perspectives on these intractable problems. While this book didn't change my mind on pretty much any aspect of theories of mind, I valued his intellectual consistency. Humphrey is from the "wrong and interesting" school of thought, in my estimation, but at least that avoids the boring. I also loved his concept of "qualiaphilia" and the natural desire our kinds of brains have for experiences of phenomenal depth.
July 29, 2023
This is a very interesting book and worth reading. My only frustration with it, and this may not the fault of the author, is that I don't feel like it gave me a good sense of the difference between an entity's ability to take information and sensations in via the five senses and its actual consciousness. It seems like the two are often conflated, which makes it difficult for me as a reader to differentiate between the two.
But the problem may be that the only way we can measure or detect consciousness in another being is to observe their sensory abilities and what limited information we can get from their reactions to them. (This is true of other humans, too, but at least we have language to bridge this gap.)
Consciousness is, without a doubt, the most mysterious aspect of the strange universe we live in. I was really hoping the book would give me more tools to help me wrap my head around this conundrum, but maybe there's only so much we can understand about it.
I do feel like Adler's now very dated but still useful and relevant Aristotle For Everybody did help me in some respects to gain a better understanding of this issue through his introduction of Aristotle's concept of forms. (See the section entitled 'Man the Knower'.) But the concept remains elusive, so I'll continue to be on the lookout for additional information.
But the problem may be that the only way we can measure or detect consciousness in another being is to observe their sensory abilities and what limited information we can get from their reactions to them. (This is true of other humans, too, but at least we have language to bridge this gap.)
Consciousness is, without a doubt, the most mysterious aspect of the strange universe we live in. I was really hoping the book would give me more tools to help me wrap my head around this conundrum, but maybe there's only so much we can understand about it.
I do feel like Adler's now very dated but still useful and relevant Aristotle For Everybody did help me in some respects to gain a better understanding of this issue through his introduction of Aristotle's concept of forms. (See the section entitled 'Man the Knower'.) But the concept remains elusive, so I'll continue to be on the lookout for additional information.
January 2, 2023
I put 5 stars for the fascinating narrative of the book. Reading it made me feel like if the author were sitting next to me in the living room, having a friendly informal
discussion about the topic of the theory of mind.
Many new insights, ideas and scientifically proven facts, provided in the book, are definitely worth to learn and read.
The author however does not even try to answer the hard problem of consciousness. This is quite disappointing, but nevertheless, the book left me with a sweet aftertaste and no regret at all of spending a few bedtime evenings in its company.
discussion about the topic of the theory of mind.
Many new insights, ideas and scientifically proven facts, provided in the book, are definitely worth to learn and read.
The author however does not even try to answer the hard problem of consciousness. This is quite disappointing, but nevertheless, the book left me with a sweet aftertaste and no regret at all of spending a few bedtime evenings in its company.
Read
July 8, 2023I appreciated Humphrey's clear views on the evolution of human consciousness. Why we have such a thing at all; how it helped us evolve as a species, and especially how it creates a unique sense of self. Of course, there are many other views of consciousness, and no one agrees where it is actually located or if it even exists, but this book added immensely to my understanding of consciousness--that is, how it feels; how it feels to see a red flower, hear a dog barking, the qualia of living.
November 2, 2023
I loved parts of this but felt like I was getting talked in circles for lots of it. Good to know distinctions in types of consciousness and that mammals and birds (warm blooded) are the only ones to reach the higher plane. I liked his stories about research ( the monkeys and the role of the Brain in seeing ) but got lost for parts of this.
January 23, 2025
Okay, gonna try to get back into goodreads... here we go!
This book took me almost a year to read. Why? I'm not so sure.
Was I interested in the topic? Yes. Is it particularly dense? No. Was I too busy reading other books? Not really. And yet for some reason this book was stuck on my bedside nightstand for the greater part of a year.
An interesting thing happened when I eventually allowed myself to start another book (also about consciousness)-- The World Behind the World, by Erik Hoel. I devoured this new book in like 3 sessions.
When I returned to finally finish Sentience, it occurred to me how *imprecise* the language and argumentation was, at least compared to the previous book. This was kind of an "aha" moment for me: I think Sentience was such a chore to read because for every compelling anecdote, every interesting line of reasoning, there'd be too much room in between those words for me to insert my own doubt or counterarguments. Even if the book itself is relatively easy to read at a surface level, this secondary effect causes me a lot of mental fatigue.
The main thesis of the book *wants* to be: evolution needed to invent consciousness, because consciousness is ultimately very useful in certain slices of the animal kingdom, evolutionary speaking. But, what you get are a series of interesting, if not sometimes rambling, anecdotes and assertions from someone who has seen, done, and thought a lot of interesting things about consciousness. Many of them I agree with, but many I find unconvincing or overreaching.
I think if I had locked myself in a room under the condition that I could not leave until I finished this book, I might give it 4 or 5 stars. But, reading this in a super disjointed way only further obscured what should have been, in my opinion, a much more focused read that stuck tighter to the main thesis.
This book took me almost a year to read. Why? I'm not so sure.
Was I interested in the topic? Yes. Is it particularly dense? No. Was I too busy reading other books? Not really. And yet for some reason this book was stuck on my bedside nightstand for the greater part of a year.
An interesting thing happened when I eventually allowed myself to start another book (also about consciousness)-- The World Behind the World, by Erik Hoel. I devoured this new book in like 3 sessions.
When I returned to finally finish Sentience, it occurred to me how *imprecise* the language and argumentation was, at least compared to the previous book. This was kind of an "aha" moment for me: I think Sentience was such a chore to read because for every compelling anecdote, every interesting line of reasoning, there'd be too much room in between those words for me to insert my own doubt or counterarguments. Even if the book itself is relatively easy to read at a surface level, this secondary effect causes me a lot of mental fatigue.
The main thesis of the book *wants* to be: evolution needed to invent consciousness, because consciousness is ultimately very useful in certain slices of the animal kingdom, evolutionary speaking. But, what you get are a series of interesting, if not sometimes rambling, anecdotes and assertions from someone who has seen, done, and thought a lot of interesting things about consciousness. Many of them I agree with, but many I find unconvincing or overreaching.
I think if I had locked myself in a room under the condition that I could not leave until I finished this book, I might give it 4 or 5 stars. But, reading this in a super disjointed way only further obscured what should have been, in my opinion, a much more focused read that stuck tighter to the main thesis.
March 19, 2025
I liked this. Humphrey does a good job at presenting neuroscientific and philosophical concepts at a level which does not require too much knowledge of either of these domains to understand. This book is both scientifically accessible in that sense, as well as substantial, because while the topics are presented in an easy-to-comprehend manner, it does not feel like the audience is being talked down to. I went into this as a non-neuroscientist, non-philosopher with an interest, but little prior knowledge, in consciousness, and this book provided me with a much deeper understanding of what it entails to be sentient.
My only complaint about Sentience is that Humphrey seems to spend too much time introducing his background and his early experiences as a budding researcher and not enough time later in the book, exploring his conclusion. With that being said, this nitpick is just my taste, and I can't deny that this book is a strong piece of science communication.
My only complaint about Sentience is that Humphrey seems to spend too much time introducing his background and his early experiences as a budding researcher and not enough time later in the book, exploring his conclusion. With that being said, this nitpick is just my taste, and I can't deny that this book is a strong piece of science communication.
February 8, 2025
A consciência cognitiva está espalhada pela Natureza; contudo, a consciência fenomenal é seletiva. Assim é a senciência. Sentimos, logo existimos.
July 13, 2025
Humphrey is a treasure, and has been so for decades. It doesn’t matter whether you agree with his arguments or not (full disclosure: I agree with most) but whether you value his questions and are willing to play. This book is full of learning, humility and playfulness while seeking to understand perhaps the most fundamental, and fundamentally weird, aspect of being human: our ability to sense and make sense of sensation.
May 31, 2024
I feel a bit odd rating this since in many ways it reads as a memoir of Nicholas Humphrey's professional evolving thoughts on sentience over his life, and hence a 5. Though perhaps a 4 because the last section is much tougher, faster, less substantiated and felt less "sticky" or graspable to me. Might be predeliction, focus (had to 2.3 speed before library return), but after reading 2 other reviewerw who espressed the sense of 3 parts being quite different: his initial reminiscing portrait of a scientist and thinker as a young man with his monkey, poppies, and ideas, essential if a bit of a ramble, To Work my favorite in which he explains the evolving understanding of sentience, phenomenal sentience across the human psychology, social psychology and zoology fields. Finally, he dives into his understanding/theories about the evolution of sentience and supposes it's strength and prominence for humans is a mammalian feature, related to being warm blooded. In the last third of the book I would have gained more perhaps from reading than listening. Though Tomo watched an hour talk on youtube a few months ago and remembers in great detail. Obviously a testament to his brain, but also my point is that this may not be a fair critique of the last third discussing Humphrey's most recent thinking, but my own distraction.
As a guide for exploration of Sentience it's a 5, I gained new understanding of how humans work particularly related to sight, but also other senses and sensations and our physical and mental processing of those.
Thank you to the author for sharing his ideas of 6+ decades for lay people. Appreciated the audio actor as well.
As a guide for exploration of Sentience it's a 5, I gained new understanding of how humans work particularly related to sight, but also other senses and sensations and our physical and mental processing of those.
Thank you to the author for sharing his ideas of 6+ decades for lay people. Appreciated the audio actor as well.
January 18, 2026
Nicholas Humphrey’s Sentience is part intellectual memoir (I felt like he wanted to stake his claims around scientific contributions), and part scientific hypothesis and a philosophical argument about why and how phenomenal consciousness evolved. The central thesis is that sentience is not a byproduct of certain kinds of cognition but a biological adaptation that nature selected because of its motivational, aesthetic, and self-reflective value. At first I thought that the book was trying to address the hard problem (around what causes phenomenal experience), but the book is actually just kind of mostly ignoring that and focusing much more on why phenomenal experience would be adaptive. And for me, making that shift in my expectations made me enjoy the book a lot more.
Humphrey begins by distinguishing sentience from consciousness. Consciousness, broadly construed, includes awareness, decision-making, and self-reflection. But sentience, he argues, is narrower and more mysterious: it’s what it feels like to see red, to taste salt, to feel pain. He roots the book in a lot of autobiographical and scientific anecdotes showing how his life experiences prompted him to take the feeling aspect of consciousness seriously. In early chapters, he emphasizes that many intelligent creatures (and machines) could be cognitively conscious without necessarily being sentient. This sets up his mission: explain why subjective experience exists at all, when the brain seemingly could do so much without it.
The next section draws on Humphrey’s own neuroscience research, particularly on blindsight, cases where people with damage to visual cortex can respond to visual stimuli without consciously seeing them. This work supports his claim that phenomenal experience and functional awareness can come apart. He explores how visual perception is not just about interpreting data but involves a layered, affect-laden experience of “what it’s like” to see. This leads to his idea that sensory experience is "thickened" by the brain to create the illusion of being in direct contact with the world. In other words, our sensations aren’t just raw data, they're affective constructions, which are strongly related to our actions. This idea kind of reminded me of another book we read in our bookclub, "The Brain from Inside Out", which postulated that, in general, the brain primarily operates through internally generated activity that "learns" by connecting external inputs and actions to these self-organized internal dynamics.
Having framed the mystery of sentience, Humphrey begins constructing his evolutionary argument. He draws a lot from his work on social intelligence, which touches on developmental psychology and comparative cognition to argue that humans (and perhaps some other animals) evolved a capacity for inner theatre as a way to present their own mental states to themselves.
This capacity, he says, didn’t evolve for more accurate perception or faster decision-making, but rather to endowe creatures with a rich subjective life that could be motivationally compelling. Sentience makes life matter to the organism. Through aesthetic richness, emotional valence, and self-awareness, sentience motivates care, desire, planning, and the protection of the self, and for social animals, a sense that its companions also have this extra "mattering."
Humphrey then goes into a bit of scientific speculation. He proposes that the brain builds sentience by creating looped simulations, where sensations and motor commands are modeled not just as signals to and from the world, but as happenings to the self. In the case of motor commands, the signals are literally copied, called an efference copy. This looping allows the brain to reprocess sensations in a way that highlights their affective and personal significance. He thinks that this probably co-evolved with warm-bloodedness, in part, because the stable internal states made the relationship between behaviors and internal perturbations more important. He uses examples from body sense, warmth, and pain to show how this processing creates an internal "performance" for an inner audience, and he discusses the senses of proprioception and orgasm sense as two extreme ends of the sensorimotor spectrum that matter. Proprioception is mostly about passively sensing where things are. As pure internal sensory feedback, it does not appear phenomenally strong. Orgasm, in contrast, is almost purely feedback of motor output and is therefore strongly salient. Most senses are some combination of sensation and motor output.
In the final chapters, Humphrey returns to big-picture questions that are always required in books on this topic: Who else might be sentient? Are animals sentient? Could AI ever be sentient? He urges caution: while cognitive behavior may be impressive, sentience requires a special kind of internal architecture. A robot that solves puzzles might not feel anything. If sentience makes lives morally valuable, we have a duty to know who (or what) has it. He is a bit bold in stating that probably only bird and mammals are sentient, and he discusses a number of paradigms to assess sentience.
I thought that the book had some interesting ideas that I hadn't encountered before but was generally too disorganized. I also thought that other big ideas in consciousness weren't fairly discussed. Humphreys is a bit dismissive toward the ideas of panpsychism and continuity without providing much argument against them. I also felt like other competing theories for sentience were just left out, such as integrated information theory and attention schema theory. I also feel like the aesthetic appeal of sentience isn't really a satisfying functional explanation for many in the scientific community. Why couldn't the brain evolve a way to care more about the world without subjective experience?
At the end, Humphrey addresses our philosophical ignorance head-on. We lack a full theory, yes, and he points out that the evidence for sentience in other animals always seems to be annoyingly inconclusive, but by paying attention to what sentience does (both functionally and existentially), we can develop better hypotheses and maybe even diagnostic tests. Sentience isn’t an ineffable mystery. Instead it’s a discoverable phenomenon that evolved and continues to evolve.
Humphrey begins by distinguishing sentience from consciousness. Consciousness, broadly construed, includes awareness, decision-making, and self-reflection. But sentience, he argues, is narrower and more mysterious: it’s what it feels like to see red, to taste salt, to feel pain. He roots the book in a lot of autobiographical and scientific anecdotes showing how his life experiences prompted him to take the feeling aspect of consciousness seriously. In early chapters, he emphasizes that many intelligent creatures (and machines) could be cognitively conscious without necessarily being sentient. This sets up his mission: explain why subjective experience exists at all, when the brain seemingly could do so much without it.
The next section draws on Humphrey’s own neuroscience research, particularly on blindsight, cases where people with damage to visual cortex can respond to visual stimuli without consciously seeing them. This work supports his claim that phenomenal experience and functional awareness can come apart. He explores how visual perception is not just about interpreting data but involves a layered, affect-laden experience of “what it’s like” to see. This leads to his idea that sensory experience is "thickened" by the brain to create the illusion of being in direct contact with the world. In other words, our sensations aren’t just raw data, they're affective constructions, which are strongly related to our actions. This idea kind of reminded me of another book we read in our bookclub, "The Brain from Inside Out", which postulated that, in general, the brain primarily operates through internally generated activity that "learns" by connecting external inputs and actions to these self-organized internal dynamics.
Having framed the mystery of sentience, Humphrey begins constructing his evolutionary argument. He draws a lot from his work on social intelligence, which touches on developmental psychology and comparative cognition to argue that humans (and perhaps some other animals) evolved a capacity for inner theatre as a way to present their own mental states to themselves.
This capacity, he says, didn’t evolve for more accurate perception or faster decision-making, but rather to endowe creatures with a rich subjective life that could be motivationally compelling. Sentience makes life matter to the organism. Through aesthetic richness, emotional valence, and self-awareness, sentience motivates care, desire, planning, and the protection of the self, and for social animals, a sense that its companions also have this extra "mattering."
Humphrey then goes into a bit of scientific speculation. He proposes that the brain builds sentience by creating looped simulations, where sensations and motor commands are modeled not just as signals to and from the world, but as happenings to the self. In the case of motor commands, the signals are literally copied, called an efference copy. This looping allows the brain to reprocess sensations in a way that highlights their affective and personal significance. He thinks that this probably co-evolved with warm-bloodedness, in part, because the stable internal states made the relationship between behaviors and internal perturbations more important. He uses examples from body sense, warmth, and pain to show how this processing creates an internal "performance" for an inner audience, and he discusses the senses of proprioception and orgasm sense as two extreme ends of the sensorimotor spectrum that matter. Proprioception is mostly about passively sensing where things are. As pure internal sensory feedback, it does not appear phenomenally strong. Orgasm, in contrast, is almost purely feedback of motor output and is therefore strongly salient. Most senses are some combination of sensation and motor output.
In the final chapters, Humphrey returns to big-picture questions that are always required in books on this topic: Who else might be sentient? Are animals sentient? Could AI ever be sentient? He urges caution: while cognitive behavior may be impressive, sentience requires a special kind of internal architecture. A robot that solves puzzles might not feel anything. If sentience makes lives morally valuable, we have a duty to know who (or what) has it. He is a bit bold in stating that probably only bird and mammals are sentient, and he discusses a number of paradigms to assess sentience.
I thought that the book had some interesting ideas that I hadn't encountered before but was generally too disorganized. I also thought that other big ideas in consciousness weren't fairly discussed. Humphreys is a bit dismissive toward the ideas of panpsychism and continuity without providing much argument against them. I also felt like other competing theories for sentience were just left out, such as integrated information theory and attention schema theory. I also feel like the aesthetic appeal of sentience isn't really a satisfying functional explanation for many in the scientific community. Why couldn't the brain evolve a way to care more about the world without subjective experience?
At the end, Humphrey addresses our philosophical ignorance head-on. We lack a full theory, yes, and he points out that the evidence for sentience in other animals always seems to be annoyingly inconclusive, but by paying attention to what sentience does (both functionally and existentially), we can develop better hypotheses and maybe even diagnostic tests. Sentience isn’t an ineffable mystery. Instead it’s a discoverable phenomenon that evolved and continues to evolve.
August 18, 2023
Humphrey is a wonderful storyteller: I wish that the first section of the book, which relates his early scientific work with what amounts to a cast of British academic weirdos, went on longer.
After that section, he lays out his theory of the evolution of social consciousness, a model that (as he makes clear!) I’m far from alone in finding unconvincing. But I appreciate that he has the courage of his convictions to take the ramifications of it seriously, and to their logical (if often silly) ends: chickens are conscious in much the way we are, octopi aren’t conscious at all, and your dog definitely has emotions like yours. I would have liked the book better if he did a better job of explaining why others in the field disagree with him, and why he rejects, for instance, the centrality of language in consciousness. But, I’m hardly the target audience: there’s not much he could have done to convince me!
Still, well written, amusing, and thoughtful. Worth reading for those interested in problems of consciousness and the mind.
After that section, he lays out his theory of the evolution of social consciousness, a model that (as he makes clear!) I’m far from alone in finding unconvincing. But I appreciate that he has the courage of his convictions to take the ramifications of it seriously, and to their logical (if often silly) ends: chickens are conscious in much the way we are, octopi aren’t conscious at all, and your dog definitely has emotions like yours. I would have liked the book better if he did a better job of explaining why others in the field disagree with him, and why he rejects, for instance, the centrality of language in consciousness. But, I’m hardly the target audience: there’s not much he could have done to convince me!
Still, well written, amusing, and thoughtful. Worth reading for those interested in problems of consciousness and the mind.
September 9, 2024
I loved the thesis and the arguments
This was a great book. I was generally persuaded by N.Humphrey's thesis on consciousness. Humphrey's arguments are not only persuasive but also infused with humor and wit, making for a compelling read. What's more, he anticipates and addresses counterarguments that have been raised by other authors, demonstrating the robustness of his theory (he often cites Dennett).
In my opinion, Humphrey has achieved a remarkable milestone by developing the first concrete, scientific, defendable, refutable, and testable theory of consciousness. And the part I enjoyed the most was his commitment to using evolutionary principles as guides.
Overall, I believe Sentience deserves five stars. If you're interested in the science of consciousness (emphasis on 'science'), this book is a must-read.
This was a great book. I was generally persuaded by N.Humphrey's thesis on consciousness. Humphrey's arguments are not only persuasive but also infused with humor and wit, making for a compelling read. What's more, he anticipates and addresses counterarguments that have been raised by other authors, demonstrating the robustness of his theory (he often cites Dennett).
In my opinion, Humphrey has achieved a remarkable milestone by developing the first concrete, scientific, defendable, refutable, and testable theory of consciousness. And the part I enjoyed the most was his commitment to using evolutionary principles as guides.
Overall, I believe Sentience deserves five stars. If you're interested in the science of consciousness (emphasis on 'science'), this book is a must-read.
May 20, 2024
A pretty good discussion of how consciousness might differ among human beings and animals. The author separates cognitive consciousness (processing/intelligence) from phenomenal consciousness (sentience/experience) and then divides the animal kingdom accordingly. (Spoiler: warm-blooded animals get the good stuff). Also interesting were the tests for determining sentience among different species. Unfortunately, the narrative devolves from grounded science into personal experience, conjecture, and even anthropomorphism. Fascinating topic!
Read
May 14, 2023DNF. I was super excited to read this as I had read a review of it, and it sounded really fascinating. Perhaps the reviewer was someone who found Humphrey himself interesting because this book seems to be about Humphrey, and frankly, I don't find him all that interesting. So, unless he invented consciousness, this is mostly a tale told by an academic, full of pedantic musings, signifying nothing more than a response to Daniel Dennett's comments on his work.
December 29, 2023
The book has a lot to offer but also seems lacking in support of its claims. There is a bit of hand waving when it comes down to how it works. I but the feedback loops theory but it goes on to say that creates "attractors " which aren't ever defined and why and how they should come about. Given this is the basis of the theory I found it sadly lacking.
The switch to talking about his dog in the final chapters seems out of place. The examples would fit much better in context.
The switch to talking about his dog in the final chapters seems out of place. The examples would fit much better in context.
April 22, 2024
The book was informative but it felt like it circled around definitions and anecdotes. The most interesting portions are towards the end of the book, where examples are explored, making the definitions more tangible and the information more accessible.
I had higher hopes for the book given the title and the topic, but somehow felt like I wasn't much more informed after reading this book.
5/10. Would not recommend
I had higher hopes for the book given the title and the topic, but somehow felt like I wasn't much more informed after reading this book.
5/10. Would not recommend
July 24, 2024
A great chronological approach of Nicholas Humphrey view on Sentience, from his first student years until his current position. Interesting ideas about consciousness in animals, and where he makes the cut between conscious and non conscious animals: warm-bloodedness. Also a lot of interesting experiment described.
Recommended reading.
Recommended reading.
July 5, 2023
Ter a consciência das nossas sensações é algo que nos torna humanos e que nos dá sentido à vida. Neste livro, entendi melhor o que é a consciência, como surgiu ao longo da evolução e se é ou não exclusiva dos seres humanos. Recomendo.
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