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Your brain hallucinates your conscious reality | Anil Seth

Your brain hallucinates your conscious reality | Anil Seth

Just over a year ago, for the third time in my life,
I ceased to exist. I was having a small operation,
and my brain was filling with anesthetic. I remember a sense
of detachment and falling apart and a coldness. And then I was back,
drowsy and disoriented, but definitely there. Now, when you wake from a deep sleep, you might feel confused about the time
or anxious about oversleeping, but there’s always a basic sense
of time having passed, of a continuity between then and now. Coming round from
anesthesia is very different. I could have been under
for five minutes, five hours, five years or even 50 years. I simply wasn’t there. It was total oblivion. Anesthesia —
it’s a modern kind of magic. It turns people into objects, and then, we hope, back again into people. And in this process is one of the greatest remaining
mysteries in science and philosophy. How does consciousness happen? Somehow, within each of our brains, the combined activity
of many billions of neurons, each one a tiny biological machine, is generating a conscious experience. And not just any conscious experience — your conscious experience
right here and right now. How does this happen? Answering this question is so important because consciousness
for each of us is all there is. Without it there’s no world, there’s no self, there’s nothing at all. And when we suffer, we suffer consciously whether it’s through
mental illness or pain. And if we can experience
joy and suffering, what about other animals? Might they be conscious, too? Do they also have a sense of self? And as computers get faster and smarter, maybe there will come a point,
maybe not too far away, when my iPhone develops
a sense of its own existence. I actually think the prospects
for a conscious AI are pretty remote. And I think this because
my research is telling me that consciousness has less to do
with pure intelligence and more to do with our nature
as living and breathing organisms. Consciousness and intelligence
are very different things. You don’t have to be smart to suffer,
but you probably do have to be alive. In the story I’m going to tell you, our conscious experiences
of the world around us, and of ourselves within it, are kinds of controlled hallucinations that happen with, through
and because of our living bodies. Now, you might have heard
that we know nothing about how the brain and body
give rise to consciousness. Some people even say it’s beyond
the reach of science altogether. But in fact, the last 25 years have seen an explosion
of scientific work in this area. If you come to my lab
at the University of Sussex, you’ll find scientists
from all different disciplines and sometimes even philosophers. All of us together trying to understand
how consciousness happens and what happens when it goes wrong. And the strategy is very simple. I’d like you to think about consciousness in the way that we’ve
come to think about life. At one time, people thought
the property of being alive could not be explained
by physics and chemistry — that life had to be
more than just mechanism. But people no longer think that. As biologists got on with the job of explaining the properties
of living systems in terms of physics and chemistry — things like metabolism,
reproduction, homeostasis — the basic mystery of what life is
started to fade away, and people didn’t propose
any more magical solutions, like a force of life or an élan vital. So as with life, so with consciousness. Once we start explaining its properties in terms of things happening
inside brains and bodies, the apparently insoluble mystery
of what consciousness is should start to fade away. At least that’s the plan. So let’s get started. What are the properties of consciousness? What should a science
of consciousness try to explain? Well, for today I’d just like to think
of consciousness in two different ways. There are experiences
of the world around us, full of sights, sounds and smells, there’s multisensory, panoramic,
3D, fully immersive inner movie. And then there’s conscious self. The specific experience
of being you or being me. The lead character in this inner movie, and probably the aspect of consciousness
we all cling to most tightly. Let’s start with experiences
of the world around us, and with the important idea
of the brain as a prediction engine. Imagine being a brain. You’re locked inside a bony skull, trying to figure
what’s out there in the world. There’s no lights inside the skull.
There’s no sound either. All you’ve got to go on
is streams of electrical impulses which are only indirectly related
to things in the world, whatever they may be. So perception —
figuring out what’s there — has to be a process of informed guesswork in which the brain combines
these sensory signals with its prior expectations or beliefs
about the way the world is to form its best guess
of what caused those signals. The brain doesn’t hear sound or see light. What we perceive is its best guess
of what’s out there in the world. Let me give you a couple
of examples of all this. You might have seen this illusion before, but I’d like you to think
about it in a new way. If you look at those two patches, A and B, they should look to you to be
very different shades of gray, right? But they are in fact
exactly the same shade. And I can illustrate this. If I put up a second version
of the image here and join the two patches
with a gray-colored bar, you can see there’s no difference. It’s exactly the same shade of gray. And if you still don’t believe me, I’ll bring the bar across
and join them up. It’s a single colored block of gray,
there’s no difference at all. This isn’t any kind of magic trick. It’s the same shade of gray, but take it away again,
and it looks different. So what’s happening here is that the brain
is using its prior expectations built deeply into the circuits
of the visual cortex that a cast shadow dims
the appearance of a surface, so that we see B as lighter
than it really is. Here’s one more example, which shows just how quickly
the brain can use new predictions to change what we consciously experience. Have a listen to this. (Distorted voice) Sounded strange, right? Have a listen again
and see if you can get anything. (Distorted voice) Still strange. Now listen to this. (Recording) Anil Seth: I think Brexit
is a really terrible idea. (Laughter) Which I do. So you heard some words there, right? Now listen to the first sound again.
I’m just going to replay it. (Distorted voice) Yeah? So you can now hear words there. Once more for luck. (Distorted voice) OK, so what’s going on here? The remarkable thing is the sensory
information coming into the brain hasn’t changed at all. All that’s changed
is your brain’s best guess of the causes of that sensory information. And that changes
what you consciously hear. All this puts the brain
basis of perception in a bit of a different light. Instead of perception depending largely
on signals coming into the brain from the outside world, it depends as much, if not more, on perceptual predictions
flowing in the opposite direction. We don’t just passively
perceive the world, we actively generate it. The world we experience
comes as much, if not more, from the inside out as from the outside in. Let me give you
one more example of perception as this active, constructive process. Here we’ve combined immersive
virtual reality with image processing to simulate the effects
of overly strong perceptual predictions on experience. In this panoramic video,
we’ve transformed the world — which is in this case Sussex campus — into a psychedelic playground. We’ve processed the footage using
an algorithm based on Google’s Deep Dream to simulate the effects
of overly strong perceptual predictions. In this case, to see dogs. And you can see
this is a very strange thing. When perceptual
predictions are too strong, as they are here, the result looks very much
like the kinds of hallucinations people might report in altered states, or perhaps even in psychosis. Now, think about this for a minute. If hallucination is a kind
of uncontrolled perception, then perception right here and right now
is also a kind of hallucination, but a controlled hallucination in which the brain’s predictions
are being reined in by sensory information from the world. In fact, we’re all
hallucinating all the time, including right now. It’s just that when we agree
about our hallucinations, we call that reality. (Laughter) Now I’m going to tell you
that your experience of being a self, the specific experience of being you, is also a controlled hallucination
generated by the brain. This seems a very strange idea, right? Yes, visual illusions
might deceive my eyes, but how could I be deceived
about what it means to be me? For most of us, the experience of being a person is so familiar, so unified
and so continuous that it’s difficult
not to take it for granted. But we shouldn’t take it for granted. There are in fact many different ways
we experience being a self. There’s the experience of having a body and of being a body. There are experiences
of perceiving the world from a first person point of view. There are experiences
of intending to do things and of being the cause of things
that happen in the world. And there are experiences of being a continuous
and distinctive person over time, built from a rich set
of memories and social interactions. Many experiments show, and psychiatrists
and neurologists know very well, that these different ways
in which we experience being a self can all come apart. What this means is
the basic background experience of being a unified self is a rather
fragile construction of the brain. Another experience,
which just like all others, requires explanation. So let’s return to the bodily self. How does the brain generate
the experience of being a body and of having a body? Well, just the same principles apply. The brain makes its best guess about what is and what is not
part of its body. And there’s a beautiful experiment
in neuroscience to illustrate this. And unlike most neuroscience experiments, this is one you can do at home. All you need is one of these. (Laughter) And a couple of paintbrushes. In the rubber hand illusion, a person’s real hand is hidden from view, and that fake rubber hand
is placed in front of them. Then both hands are simultaneously
stroked with a paintbrush while the person stares at the fake hand. Now, for most people, after a while, this leads to the very uncanny sensation that the fake hand
is in fact part of their body. And the idea is that the congruence
between seeing touch and feeling touch on an object that looks like hand
and is roughly where a hand should be, is enough evidence for the brain
to make its best guess that the fake hand
is in fact part of the body. (Laughter) So you can measure
all kinds of clever things. You can measure skin conductance
and startle responses, but there’s no need. It’s clear the guy in blue
has assimilated the fake hand. This means that even experiences
of what our body is is a kind of best guessing — a kind of controlled
hallucination by the brain. There’s one more thing. We don’t just experience our bodies
as objects in the world from the outside, we also experience them from within. We all experience the sense
of being a body from the inside. And sensory signals
coming from the inside of the body are continually telling the brain
about the state of the internal organs, how the heart is doing,
what the blood pressure is like, lots of things. This kind of perception,
which we call interoception, is rather overlooked. But it’s critically important because perception and regulation
of the internal state of the body — well, that’s what keeps us alive. Here’s another version
of the rubber hand illusion. This is from our lab at Sussex. And here, people see
a virtual reality version of their hand, which flashes red and back either in time or out of time
with their heartbeat. And when it’s flashing
in time with their heartbeat, people have a stronger sense
that it’s in fact part of their body. So experiences of having a body
are deeply grounded in perceiving our bodies from within. There’s one last thing
I want to draw your attention to, which is that experiences of the body
from the inside are very different from experiences of the world around us. When I look around me,
the world seems full of objects — tables, chairs, rubber hands, people, you lot — even my own body in the world, I can perceive it
as an object from the outside. But my experiences
of the body from within, they’re not like that at all. I don’t perceive my kidneys here, my liver here, my spleen … I don’t know where my spleen is, but it’s somewhere. I don’t perceive my insides as objects. In fact, I don’t experience them
much at all unless they go wrong. And this is important, I think. Perception of the internal
state of the body isn’t about figuring out what’s there, it’s about control and regulation — keeping the physiological variables
within the tight bounds that are compatible with survival. When the brain uses predictions
to figure out what’s there, we perceive objects
as the causes of sensations. When the brain uses predictions
to control and regulate things, we experience how well
or how badly that control is going. So our most basic experiences
of being a self, of being an embodied organism, are deeply grounded in the biological
mechanisms that keep us alive. And when we follow this idea
all the way through, we can start to see
that all of our conscious experiences, since they all depend on the same
mechanisms of predictive perception, all stem from this basic
drive to stay alive. We experience the world and ourselves with, through and because of
our living bodies. Let me bring things together step-by-step. What we consciously see depends on the brain’s best guess
of what’s out there. Our experienced world
comes from the inside out, not just the outside in. The rubber hand illusion shows
that this applies to our experiences of what is and what is not our body. And these self-related predictions
depend critically on sensory signals coming from deep inside the body. And finally, experiences of being an embodied self
are more about control and regulation than figuring out what’s there. So our experiences of the world
around us and ourselves within it — well, they’re kinds
of controlled hallucinations that have been shaped
over millions of years of evolution to keep us alive in worlds
full of danger and opportunity. We predict ourselves into existence. Now, I leave you with three
implications of all this. First, just as we can
misperceive the world, we can misperceive ourselves when the mechanisms
of prediction go wrong. Understanding this opens many new
opportunities in psychiatry and neurology, because we can finally
get at the mechanisms rather than just treating the symptoms in conditions like
depression and schizophrenia. Second: what it means to be me
cannot be reduced to or uploaded to a software program running on a robot, however smart or sophisticated. We are biological, flesh-and-blood animals whose conscious experiences
are shaped at all levels by the biological mechanisms
that keep us alive. Just making computers smarter
is not going to make them sentient. Finally, our own individual inner universe, our way of being conscious, is just one possible
way of being conscious. And even human consciousness generally — it’s just a tiny region in a vast space
of possible consciousnesses. Our individual self and worlds
are unique to each of us, but they’re all grounded
in biological mechanisms shared with many other living creatures. Now, these are fundamental changes in how we understand ourselves, but I think they should be celebrated, because as so often in science,
from Copernicus — we’re not at the center of the universe — to Darwin — we’re related to all other creatures — to the present day. With a greater sense of understanding comes a greater sense of wonder, and a greater realization that we are part of
and not apart from the rest of nature. And … when the end of consciousness comes, there’s nothing to be afraid of. Nothing at all. Thank you. (Applause)

100 thoughts on “Your brain hallucinates your conscious reality | Anil Seth

  1. Consousness does not rise much in a competitive society , if we had a society based off coroperation and helpfulness then people would work together to figure out all problems and we would have true evolution, nowadays if they find alien life they won't even tell u, how can consousness rise much without a joint effort of mankind as a species, even the ant has outdid man in this effort

  2. Science that's backed by unsubstantiated science. Is that science or is that itself is a hallucination? If we all hallucinate the same thing than at what point does it become a reality? Hmm. Sounds like we're trying to develop the theory of relative reality. Wait, relative reality, is that an oxymoron? Help Alice, this rabbit hole is going too deep. I'm throwing my acid in the trash and going back to smokin dope.

  3. unproven assumption seconds into the video that the brain generates consciousness or a "conscious experience". No evidence what so ever that the brain "generates" consciousness.

  4. I think he said that if hallucination is a type of perception therefore perception is a kind of hallucination…. ok if that syllogism holds true then all dogs(hallucinations) are mammals(perceptions) therefore all mammals are dogs……….. sorry that doesn't work. thanks for playing

  5. Every living complex or not so complex cellular structure all have sensory organs and a command centre or a brain to best understand the world we or being it other living creatures survive in. All living things try to finetune their sensors over years of DNA evolution in order to overcome obstacles and see and understand their surroundings relevant to them as best as possible. A combination of these or more or more complex sensory system makes up our consciousness but because we are humans we see it more apparent to each and every individual., and we have also the most complex multiple sensory system fine tuned to our bodies to best understand our world and now the broader universe we now try to explore.

  6. You got it backwards, consciousness hallucinates the brain, along with the rest of reality. Consciousness comes BEFORE material reality

  7. What i believe is what we really are is just a brain+stem that needs a body to navigate the physical world. Sperm looks just like a brain+stem.

  8. Sure, the bold guy in a robe says he is not real…until him, or me, smashes his thumb with a hammer, and all illusions of unreality dissipate…

  9. Curious. Why wouldn't AI become conscious? That there will never be hardware good enough? That its too complex to model? That we will never be capable of inventing an adequate machine code? Or that we won't have time to achieve it before the lights go out?

  10. Hmmm, If he ceased to exist from the effects of anesthesia then his computers operating system must stop existing when he turns the power off…. Interesting Idea, most people leave this kind of reasoning behind at age 2 or so once the concept of "object permanance" manifests.

  11. this is how I feel when I experience derealization, like life is fake and I become uncomfortably hyperaware of the reality around me.

  12. I always wondered when I had some dreams that look so real if it would be memory or reflexes of others universe. We know that fiscally we couldn't travel through black holes because we would disintegrate, but how about our consciousness?
    I remember that on those dreams, in few of them I was more evoluted living in a evoluted society, in other I was very primitive trying to survive. Would be those parallel universes?

  13. How about if the consciousness is like a web where each perpendicular point is the consciousness of a being and when we die we just disconnect our physic body from this spot? We can freeze a body but we couldn't reanimate the body because we can't keep the consciousness right? How about if we were able to mape this web and saving it as a Cartesian plane, and save those spots as coordinates, and when we reanimate the frozen body we would use some technology to reconnect the body with that exact coordinate? We could relate the DNA from each body with the coordinate correspondent in the Cartesian plane.

  14. Pure scutter hei. Flaggin, naggin and a bag a glue man and you’ll be riding bb baskin at the Galway races. Fact

  15. A few holes here, one the consciousness or Awareness of "I am" is not connected to the body as there is no body, there is no you. Everything is nothingness and nothingness is everything. Second science is man made truths aka untruths. To blindly believe in science is to reinforce your own illusion that ego has crafted for you.

  16. What a philosophical and scientific load of crap!

    Epiphenominalism (which seeks to explain all phenomena based on physics and chemistry emerging to create hallucinations we take to be real has suffered for the last half-century in philosophy and science as incoherent! Lack of knowledge of scholarship in both fields is required to give a thumbs up!

    “You can fool all of the people some of the time.”


    But ignorant people you can fool all of the time. Great speech.

  17. Excellent, most excellent. We literally see nothing directly; the brain received visual input and passes along its interpretation. That's what we see.

    Since losing much of my sight I've been fascinated to discover how much information my brain fills in depending on what I expect to see. A crystal vase on my bookshelf is notable for its clarity and distinct vertical lines.

    During a recent cleanup binge the vase was briefly replaced with a tall transparent spray bottle filled with H2O2. Until I got quite close to it I saw the crystal vase. It was as if my brain processed only two or three familiar properties and filled in the rest based on what was usually present. This is entirely different from Charles Bonnet syndrome and may provide insights into a kind of perceptual shorthand the brain uses for routine recognition…my brain, at least.

  18. "Right now, billions of neurons in your brain are working together to generate a conscious experience" So your saying consciousness is just billions of neurons? I didn't think we could isolate consciousness. We don't know because it's being witheld from us. Why? Knowledge is power. Using the fear of the unknown to tighten the shackles on humanity and keeps the slave mill turning. Discover the lies with me on my new channel! New video: https://www.youtube.com/watch?v=WvHjfirfAUo&t=492s Like, Subscribe, Share if you want more TRUTH

  19. Great insights. A must-see for everyone. However, I would like to comment about the last thing he said – "when the end of consciousness comes, there's nothing to be afraid of, nothing at all". Well sure, I agree, but that is uncontroversial and trivial. The exciting question is whether or not death is the end of consciousness.

  20. DMT Videos Lead Me Here.. Jim Carey Said It 1st.. People In The Comments Making Jokes. The Real Joke Is On You Unfortunately. And Everyone Knows It But You

  21. the world is a lie – space time continuum, before christi


  22. I've undergone nine surgeries with deep anesthesia within the past five years. Perhaps we 'travel' (or whatever becomes of our consciousness) to a mysterious other side of time, where there is no-thing and no time. For several days after every anesthetic experience, my brain offered up deeply vivid dreams of other places/spaces and other times in history. It was as if I were re-experiencing wherever or whatever my consciousness underwent during surgery. There was a bit of "magic" about it all. It made me all the more aware of the distinction between "brain" and "consciousness."

  23. I take it at the end of his speech when he said that there's nothing to be afraid of at the end of our consciousness, nothing at all, that we are finite souless beings destined to Oblivion. It's this kind of thinking that reduces humanity to an animal without morals and that there is no good or evil. The complexity of life requires intelligent design and this can be supported mathematically. One living creature is more complex than any object in the universe. The chances of one protein forming is 10 to the 164. Multiply that by blocks of time needed for the process and entropy, which seems to be the dominant process in the universe and you are approaching infinity if not exceeding it. Humanities smug arrogance of confidence in what we know, knows no bounds. We greedily accept facts and nonsense equally. Our history with wisdom and knowledge has been modified with every generation. That essence that animates life cannot be duplicated and never will. An intelligent Creator is more plausible than the dark chaos science relies on. Science is as prejudiced today as it was in the 15th century. Don't get me wrong. Science is a wonderful and satisfying pursuit if you don't turn it into a religion. I believe science is a concept that God used to create our universe and that science supports this. Secular Science has become a dictator that will blindly resist opposing evidence. My confidence in God the Creator is not challenged by science and is satisfyingly confirmed by it. God's existence does not depend on our reality but our existence depends on God. We are stuck in a continuous loop of circular reasoning no matter what position you take. If you understand "blessed assurance" then you'll understand my confidence in God. Without God our existence has no meaning or purpose when we die. The worst people that ever lived were atheist and evolutionist. By their standards there was neither good nor evil so ruthlessness and atrocities had no meaning and this theme will continue until Jesus returns.

  24. I'd just like to say that there seems to be and is a lot of here say in this video: and honestly if you think about it at least a very large part of a "sense of self" ultimately is the realization that the is an indavidual being (if you will) at least as much as anything else, and while I obviously have no idea if we will ever be able to create a sentient A.I. I do know that a part Of sentience is the ability to ask a question: and so far as I understand anyway the mind cares just as much about making sure that everything that should be there is there and functioning properly as much as anything else: and that while yes the can be taken in by illusions and or hilucinations etc. and that there is no "nature" or "un-nature" or "natural" or "unatural" however there is the environment in which we live remember that reality is reality and that reality simply is: and that while it is by no means foolproof taking an active role in ones own functioning can (and does,) most certainly help with the avoidance of misinterpretation shell I say: and lastly that while there may well literally be nothing to fear that does not mean that the should not be afraid (at the very least in the sense of having a healthy fear if you will;) for and if only because life is something death is nothing therefore life is preferable to death and that evolutionarily speaking there are some danm good reasons for certain things being the way that they are if only because we would not be alive today if they were not: so let's just absolutely do and do try to survive and live and remember that our brain just like any part of the body has it's limits and try to work with ourselves shell we…:)

  25. This guy is way too excited about passing off a few graphic design projects and some mumbo jumbo woo off as science.

    "Your brain is the controller trying to keep all these VARIABLES within special RANGES….. no no our consciousness can never be digitized never, remember all that magical life force stuff I said was crazy and naive? Yeah we're still doing that with consciousness lolz"

  26. And yet, there is still no proof that our thoughts originate from inside our brains or that when we “die” we cease to be.

  27. sooner or later… if you think about everything enough… you will only ever be that… a shell of a human being obsessed with questioning questions

  28. That's the thing with those kinds of freaks. I wonder if he would still think that he hallucinates his conscious reality if I punched him right in the face. These people have a specific work to do, that is to drive you right through the rose garden, instead of helping you searching for the truth, as we all should do.

  29. Absolute nonsense must be so wonderful to live in a materialists' hallucinated world were free will, responsibility, ethics and morality go to die.

  30. his brain, hallucinating his hallucinations under the power of the deceiver John 8:44; as he exists in 1John 2:16 pride, which is not of the Father.

  31. Society keeps us all the same. Anyone that strays out of the box is labeled with a mental illness. Just saying. There is no wrong or right reality.

  32. We predict ourselves into existence. And then that prediction is excreted out into matter, and we get roads, rumble pads, rhythm, rivita, regulatory agencies, etc. Then, that matter becomes "the matter" of consciousness, and we slowly are churned back into being, as becoming. What annoys me about this neuroscience "discovery" is that it re-formulates a mode of thought that dates back to at least the 2nd Century AD, with Nargarjuna and his re-application of Buddhism. Just as the ease of an unquestioned existence of a continuous self prevailed back then, so too will it now, and Seth will join a pantheon of other minds, who say, all of one voice "it takes a universe to make a human to know a universe."

  33. Jesus wanted us to recognize that we need a mirror to see our faces. Put some thought into this and it will reveal what Jesus was speaking about….

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