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)

Comments (100)

  1. Its no doubt that most left wingers are living in there own messed up hulucantion.

  2. Bill Hicks figured this out decades ago..

  3. Perfect video to see if you have existamental ocd😂😂 gotta do them exposure's tho😛

  4. Please please please someone tell my brain THANK YOU for hallucinating Haagam Daas Caramel Cone Ice Cream!!!

  5. You just had to throw brexit in their right because there isn't enough polarity in the world? Lost all respect for you right there! Keep that crap at home if you're going to talk about science!

  6. He bases all of his arguments on something that science hasn't yet proved. "Billions of neurons somehow generate conscious experience" Although seemingly likely, this has not yet proved.

  7. #1 rule of public speaking: hide the rubber hand prop until it's time to explain it

  8. What if dreams are reality only the atoms and molecules are spread further apart?

  9. Your mind literally creates your reality. It's not only what your mind perceives from external world but how it's been primed internally.

    Watch "Brainstorm Green needle" on youtube.
    If that's true, it means your whole reality can shift, it can be changed if you can change the way your mind interprets everything by priming your mind.

    We have all received the message now my children hahaha Good Luck and have an awesome day everyone 🙂

  10. So are you speaking or I am in hallucination

  11. Dude if someone came from no were with a nife and stab something it would scare me as well.

    So this experiment does not prove anything.

  12. “And when the end of consciousness comes, there will be nothing to be afraid of. Nothing at all.”

    I’ve been having major death anxieties stemming from the fear of permanently losing consciousness and having my loved ones also die. For some reason, watching this video and hearing this quote actually made me feel a little better and helped me cope with my mortality. We are all part of nature, not apart of, and our consciousness is an amazing, but momentary phenomenon in this vast universe.

  13. His fckin turkish accent kills me

  14. sorry dude but science has proven that "thought" can make changes to physical matter.. consciousness is the creation of the universe.

  15. Brain is a prediction machine..I like that

  16. Currently having an existential contemplation at six in the morning and this video just describes life so intellectually and perfectly. Have fun in life, because in the end it all comes down to your perception on life and how you make of the experience. Consciousness is something us humans are never going to be able to completely understand.

  17. Our perception of reality changes reality.

  18. Joe rogan wants to know your location

  19. Reality is a controlled hallucination..that one hit me hard..

  20. They let anybody have these, huh?

  21. I heard those weird sounds ,but mine sounded like birds. The more I listened the clearer they became . It tells me when I'm driving to be careful police are near by . Etc.

  22. You can’t have a hallucination without a consciousness observing the hallucination

  23. It’s not your brain ! ITS YOUR SOUL. ! Your Soul runs your body !

  24. Great talk. Disappointing comments.

  25. We predict ourselves into existence.

  26. TED + European accent + headset and little clicky device to change frames = TRUTH

  27. The last words. Was it to calm people who are scare to die, or was it to eliminate religious thoughts? If you say the wondering about life does not stop with a scientific approach, then a religious hallucination does not need to be elimated.

  28. Once people forget God they invent all kind of stupid theories…Your mind doesn't hallucinate anything it's all real,stop watching this kind of videos and Trust the creator of all..

  29. Reality is not an illusion you fuckin dickheads, you are just witnessing the human nature of reality…OMG

  30. My brain halllucinated this lecture? Wow I am super smart.

  31. All of these facts or principles already explained in vedas thousand years ago which were ignored and forgotten, now resting same in slight different manner and claiming it as inventions.

  32. What's he been smokin?

  33. Leave your political ideas out of it man.. FFS… annoying sometimes.

    ….. PAYING TO BE ' heard ' 😉 😉

  35. He looks like a robot. I can sure that unless I heard his last 1 minutes of the lecture. The most important part of the lecture, this cannot be said by a robot..

  36. How can all of us simultaneously experience the same hallucination though?

  37. watch it high
    you will get the answers..

  38. Then there is the breath of life , our spirit and soul, that only god can give you.

  39. I have a hormone house. It is my DNA. It is adrenaline in me. It is the race. I run , I race and feel better all the time. It is adrenaline. My adrenaline make me hallucinate I am in other words crazy. But since I am an Atheist this stops. And I am dead. Since no adrenaline, no DNA, no hormone no inside dope and inside drugs, I am dead. So , I am a Christians. Through Christ I found life and he gave me life and I keep life. But as an Atheist, I do not live long and without soul, creativity and christ and logos and the word of god called spells or formula's as called witchcraft. Get it now? We are actually all crazy witches christians. But alive. :O

  40. so if you and everything else is halucination of my brain, then you wont mind giving to myself a brand new car, ton of cash and woman.

  41. So those snitches that the cartels literally cut into pieces while alive with chainsaws are just imagining it? And all those women in rape farms…all those children kidnapped, raped, sodomized, and murdered, are what, fantasizing?

  42. Heads up scientists: Just because no one knows how consciousness works doesn't mean it's an illusion…

  43. I think. Therefore I am. He danced around to basic question. How do I know that I exist? And, why shouldn't death be scary?

  44. Anil Seth does not exist as an objective independent consciousness. He is an invention of my brain as you and the entire world are.

  45. I need the cliff notes version of this video. Woah. Mind-blowing.

  46. This is so spiritual.

  47. I'm having a headache…

  48. He just said imagine being a brain, we are own brains though cos if you think about it it's the very organ for where thoughts and emotions are and you can't survive without a brain. I think so there for I am

  49. You think Brexit is a terrible idea.

    Bye bye 👎

  50. if i had my own planet i’d have my own reality not this one can you now understand who manipulates your reality?? other people…that’s why people try to control others so much they wish they were in their own reality and it isn’t going to happen nice try though

  51. I never though about my brain be something more than me. And you say that i am not i but my brain is . And im only a story . Im scared Dave😭. We dont think about us as "the brain" . Im so confused 😵

  52. Right such nonsense blah blah blah nothing exists lol except the lies science creates such as dark matter and gravity Tesla stated it’s purely an electric universe, science is nothing more than a religion now.

  53. Very interesting theory about consciousness.

  54. Wow this is stupid.

  55. I wish I'd hallucinate about 2 million dollars

  56. Makes sense with some Valuable insights – just badly framed and an ending to forget!!! But I guess what do u expect from focusing only on science to understand things like that!

    I believe that understanding consciousness better will never come solely from science… spiritual awakening is a MUST

  57. the end of conciousness? how does that happen?!

  58. It's my world, you're all just living in it.

  59. By the mother of stream of consciousness writing:

  60. really dude? i wonder how hallucinating would it be for you to punch you in the nose with that statement! ?

  61. Lets assume that our body is only a perception from within and we make it a reality. So why is it that we all have the same hallucination as to where our organs are placed? Everybody has a heart in the same place. Is it possible that if we are hallucinating our reality, (which i believe) we are all hallucinating the same thing, like some type of collective hallucination?

  62. How is it then, that we all agree on the hallucinations that we are having at the same time?

  63. René Descartes explained this in 1647 … i suggest all of you to read his meditations ''Méditations Métaphysiques"

  64. It's funny how those who are completely unable to fathom this theory are the first to ridicule it or patronize the idea. These comments are quite depressing. I was hoping to find intellectual consideration of the topic instead of imbecilic examples of what they presume this to be about. It's as though people heard hallucinations and just ran with it.

  65. Incompleteness fallacy

  66. I JUST started watching "Seth" converse and I'm gona stop here and watch this later. I'm extremely curious about when people start to "die" and what they experienced; those who've lived through it. I almost died 2-15-13. And it was the 1st time in my life I hallucinated, 5xs exactly. I "knew" what I was seeing wasn't real. But I also knew that they were "things" in real life I either hated or had a scare from. Not much in my life has ever scared me, I grew up tough. But these hallucinations I was able to shrug off quickly. It was the last hallucination which was auditory the really surprised me and saved my life! Till later…

  67. 5:27 no don't be fooled, the two images are different shades and are purposely confusing to make you believe differently. if I took that image printed out and I cut the two pieces of paper apart and set them side-by-side they would be very different colors, the only colors alike or the ones on the right side which already appear to be. they are betting on people not differentiating between slight variations in color

  68. neuroscientist —> Doesn't know spleen position. Seems Legit.

  69. 😮

    in bd

    may invent or did ivent……….


    cz i m everywhere

  70. 🤔…………….😳

  71. Brain is hallucination. This is hallucination.

  72. Do the presenters go through some sort of TED standards prep? They sound all the same: robots.

  73. Is seriously no one going to comment on the fact that he ends the ted talk on nihilism and the utter extinguishing of your bodily consciousness

  74. Brexit's a great idea! Get GB out of EU!

  75. This is freaking me out

  76. So there’s no way to prove what is real and what isn’t then? This could really just be a mass hallucination? I mean it doesn’t feel real, it never has. I’ve never felt like a part of anything, in control of anything, just like a watcher using this thing that’s supposed to be me to try to interact with the things around me. Trying to make sense of it all, asking questions about everything until I shut up about it because clearly I’m just an idiot that doesn’t get anything. But to me there has never been much of a difference between dream and awake, they are just two different places, that’s all.

  77. The brain is a physical thing we can weigh, measure and hold. The mind is not. Energy is physical, but the mind, our very thoughts are something else we cannot explain. I don't think that our minds hallucinates anything but perhaps our brains do since they are part of this physical realm we live in. Our minds are able to imagine ourselves traveling out of this solar system yet or physical brains do none of this. This doesn't explain anything and leaves more questions then answers.

  78. "When the end of consciousness comes, there is NOTHING to be afraid of"… Yes, I believe that is the problem haha

  79. Thats how it looks, when you get lost on a completely wrong path. There is no self and the world. Thats also just an illusion the brain creates. There is only conciousness and conciousness is prior to everything. Conciousness doesnt get created, conciousness creates everything. The brain trying to figure out what conciousness is, is like a hammer trying to figure out, what swings it by looking at the nail. The approach of Anil Seth is hopelessly bound to end up in frustration.

  80. hahahaha theres an actual ted talk abt the crazy thing i was thinking about

    Understand this tho

  82. Oh, heroic heuristics …

  83. this is a pyramid i built out of cardboard from a cropcircle of a hypercube. yeah.

  84. I was recently on a flight from Thailand and as I slept I dreamt that I was driving my car and a rocket was flying overhead. I believe because of the roar of the aircrafts engines my mind used its best guess to determine the source of this sound and expressed this as the rocket in the dream

  85. I LOVE general anesthetic. I would elect to do it every few months just for the rest. Of course every animal is conscious.

  86. "When the end of consciousness comes, there is NOTHING to be afraid of" Based on everything you just said, which was extremely smart, until you got to this part, it became contradictory. You have no way of knowing that. You can create ways of knowing it, but the unfiltered, non-hallucinated truth will remain as it is.

  87. You couldn't be more WRONG about life not being due to some life force essence. It's called the SPIRIT, and without it, the body is completely dead, even though that body still has ALL of the DNA and Neural Networks and chemistry it had before death! What's the difference? Simple, a living body has this mystical life force "SPIRIT" The dead body does not! If as you claim science knows life is simply due to chemical motion then we should have created life in a laboratory by now, and yet, brilliant scientists have attempted and failed to this present time even to create the simplest life through chemistry…it isn't Chemistry that is the spark of life…it is the SPIRIT! The most we have ever made in lab were very basic amino acids and they were all of the right handed type, yet in biological organisms all amino acids are of the left handed type, so even the basic amino acids created in lab were the completely wrong types! Again…WITHOUT THE SPIRIT (True source of consciousness and awareness of self) There is NO LIFE even with all the necessary chemistry present and even put together! By the way consciousness is NOT dependent upon having a body either. Consciousness doesn't end, because it's source is eternal…therefore it also is eternal.

  88. Dude doesn't know where the liver is. Can't take him seriously.

  89. He lost me with his Brexit opinion.

  90. They do not take people serious after use the word hallucination. But what you see is real. People do not hallucinate.

  91. My Logic :- shattered

  92. There is no self.
    – The Buddha

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