your sense of self
is a hallucination your brain made up
what you see before you and what you hear
even the me that is watching this video right now
may not be real
it is not that the world is fake
it is that you believe you are perceiving the world
when you have actually been imagining it all along
this illusion is so precise
that you have never once doubted it
hello
everyone
I am Leo Wang
in this episode
I want to take you inside the mind of one man
his name is Anil Seth
professor of cognitive and computational neuroscience at the University of Sussex
and one of the most prominent researchers in consciousness science worldwide
he did his undergraduate degree at Cambridge
and earned his doctorate in computer science at Sussex
he has published more than two hundred papers
and ranks among the top zero point one percent most cited scientists in the world
his talk on consciousness
has been viewed more than fifteen million times online
the book he published in 2021
whose English title is Being You
shot straight into the top ten of the UK bestseller list
and was translated into more than ten languages
when he was eight or nine
he was standing in front of the bathroom mirror
when he suddenly realized he was going to die someday
this was not abstract knowledge
it was really feeling that the person in the mirror would one day vanish completely
that moment hit him like lightning
he started asking
who am I
why am I me
why am I here and not somewhere else
these questions have haunted him ever since
later he studied natural sciences at Cambridge
then after graduating he switched to computer science and earned a doctorate
because he understood
that to understand consciousness
philosophical speculation alone is not enough
you have to model it with mathematics and computation
let us start with one question
there is a famous puzzle in consciousness research
called the hard problem of consciousness
raised by the philosopher David Chalmers in 1995
it asks
why a physical brain can produce subjective experience
why the firing of neurons is not just information processing
but comes with an experience of what it feels like
this question has troubled the field for decades
and there is still no agreed answer
the attitude Seth takes here is interesting
he does not deny that the hard problem exists
but he suggests we may not need to solve it first in order to understand consciousness
he offers an alternative
the real problem of consciousness
note
not the easy problem
but the real problem
what he means is
rather than agonizing over the metaphysical puzzle of why matter produces experience
we should first work out how the brain actually generates specific conscious contents
where does the red you see come from
how is the pain you feel produced
and that feeling of being me
what mechanism does the brain use to make it
Seth believes
that once these concrete hows are worked out
the why may simply dissolve on its own
just as in the history of life science
people once argued about what mysterious substance the life force was
then as understanding of DNA proteins and cellular mechanisms deepened
the question simply disappeared
nobody ever actually solved the life force problem
it just stopped being a problem
this line of thinking is illuminating in itself
but what is truly stunning about Seth
is the answer he gives next
he says
consciousness is essentially a controlled hallucination
you may think that sounds exaggerated
a hallucination
the table I see the phone I touch the warmth I feel
how could those be hallucinations
here is how Seth explains it
the brain is locked inside a dark and silent skull
it never touches the outside world directly
all it receives is a mass of electrical signals from the eyes ears skin and internal organs
these nerve impulses have no color no sound no temperature
they are just electrochemical pulses
so where does the rich and colorful world you see come from
Seth says
the brain guesses it into being
the brain does not passively receive information and then present it to you
it actively and constantly generates predictions about the outside world
based on past experience and internal models
it first guesses one version of the world
then checks it against the sensory signals
if the prediction roughly matches the signals
the brain concludes that this is how it is
if there is a gap
it adjusts the prediction to shrink the error
this is the core of predictive coding theory
the world you see is not the world itself
it is the best guess of your brain
usually that guess is close enough to reality
so you notice nothing strange
but it is still fundamentally a model generated inside your head
Seth calls it a controlled hallucination
hallucination because everything you experience is generated inside the brain
not handed to you directly by the outside world
controlled because sensory signals keep calibrating and constraining it
so it does not float free of reality the way a dream does
think for a moment about what that means
the colors you see right now the sounds you hear the body you feel
are all made up by your brain
the difference between normal perception and hallucination
is not about true or false
it is about whether the predictions of the brain are kept in check by sensory data
try a small experiment
close your eyes for three seconds then open them
did it feel like the world suddenly appeared
it did not
in that instant the brain regenerated its predictive model of the world
and projected it as visual experience
the moment you open your eyes
what the brain does is no different in essence from a painter painting
it just paints so fast and so well
that you mistake yourself for seeing rather than painting
to prove this
Seth built an experiment called the hallucination machine
his team combined the Google Deep Dream algorithm with virtual reality
volunteers put on VR headsets
and watched real footage of the Sussex campus
but the images were processed by the algorithm in real time
so distorted patterns that were not there surfaced everywhere
dog faces eyes strange textures
just like a dream
what happened
the experiences reported by twelve volunteers
closely matched the descriptions given by people who had been through deep dream states
note
they took no drugs at all
they only watched a piece of algorithmically processed video
Seth uses this to show
that your conscious experience
even the strangest kind
depends fundamentally on how signals are processed inside the brain
change the way they are processed
and you change how the whole world looks
that is startling enough
but Seth goes further
he says
not only is the outside world a controlled hallucination
so is the self you perceive
you feel there is a stable continuous unchanging me living inside your body
but Seth says
that this me is equally something the brain makes up
he proved this with another experiment
adapted from the classic rubber hand illusion
hide your real hand
put a fake rubber hand in front of you
stroke both of them at the same time
and before long you feel the fake hand is your own
this shows that the sense of body ownership
the sense that this is my hand is built by the brain
and can be manipulated
Seth upgraded this experiment
using a Microsoft motion sensor and a pulse sensor
he created a virtual hand in virtual reality
and made its color change with the rhythm of the heartbeat
every time the heart beat once
the virtual hand flickered slightly
the results showed
that when the flickering was in sync with the real heartbeat
you felt far more strongly that the hand belonged to you
the sense of self the sense of body ownership
could be steered by the rhythm of a heartbeat
this reveals something profound
the sense of self does not come from some fixed core
it comes from the brain predicting and modeling the signals inside your body
heartbeat breathing gut sensations and other internal signals
are integrated by the brain into a predictive model called me
it is so stable and so continuous
that you have never doubted it is real
you can feel this for yourself right now
put your attention on your heartbeat
try to feel it
can you sense that beating
that is exactly the brain using heart signals to maintain your self model
when you attend to your heartbeat
you are actually watching the brain manufacture you
but it really is only a model only a prediction
a controlled hallucination the brain keeps running
from here
Seth puts forward his most central and most controversial idea
the beast machine theory
beast meaning animal
he argues the root of consciousness is not thinking reasoning or language
but being alive itself
the most basic job of the brain is not to understand the world
it is to keep you alive
to do that
it has to constantly monitor and regulate body temperature blood sugar
heart rate blood pressure oxygen levels and other physiological parameters
keeping them within a safe range
this is homeostasis
Seth points out
that consciousness emerges precisely from homeostatic regulation
in order to stay alive
the brain has to build a predictive model of the state of the body
this model does not just run in the background
it also produces emotion desire comfort discomfort
hunger fatigue and other experiences you feel in your bones
these are not decorative extras
they are the tools the brain uses to drive you to act and stay alive
so the way Seth sees it
consciousness is first of all the feeling of being alive
the most basic experience of existing in the world as a flesh and blood creature
the higher contents of consciousness
perceiving the outside world knowing yourself thinking and reasoning
all rest on that bottom layer the feeling of being alive
this leads to a sharp question
is AI conscious
Seth answers clearly
no
at least the AI we have today is not
the reason is not that AI is not smart enough
it is that AI has no body
if the root of consciousness is the homeostasis that keeps a living body going
then a system that never eats never breathes and never dies
is missing the basic condition for consciousness to arise
large language models can process vast amounts of information and produce answers that look intelligent
but they never have to worry about surviving
there is no homeostasis
no signals from internal organs
and no underlying drive saying I must stay alive
Seth does not claim that AI can never be conscious
he stresses that if we want it to have consciousness
we may need to give it some form of body and a physiological balance it has to maintain
simply adding compute and training data is nowhere near enough
this view is both fascinating and contentious
because it means consciousness is not a byproduct of intelligence
it is a byproduct of life
you can be very smart and have no consciousness
and you can be quite dim and still be conscious
a mouse may be more conscious than the most powerful AI
because it has a body it must keep alive
it gets hungry it gets scared it wants to live
while AI no matter how powerful
is never hungry never afraid
and never craves survival
now let us bring these scientific findings back to everyday life
psychologists noticed long ago
that most everyday anxiety and suffering does not come from what actually happens
it comes from the story the brain tells about the self
psychology calls this self referential processing
the brain keeps weaving stories about me
am I good enough
what do others think of me
what will the future be like
this self narrative engine never stops running
and it manufactures a huge amount of threat and anxiety that does not exist
Aaron Beck one of the founders of cognitive behavioral therapy found
that the core mechanism of depression and anxiety is exactly a self narrative gone off track
the predictive model of the brain skews systematically toward the negative
you are not really bad at all
the I am not good enough story your brain writes is just too convincing
so you mistake the story for reality
the theory Seth offers gives a deeper explanation for this
the reason you get trapped by self narrative
is that you never realized that me is itself a model built by the brain
once you see this clearly
and understand that me is not a fixed entity that needs protecting
but a prediction the brain keeps updating
a layer of buffer appears between you and those painful self narratives
this is not mysticism
experiments already back it up
neuroscientists found
that during mindfulness practice when attention rests on the breath and bodily sensation in the present
and does not follow the stories the brain generates automatically
the brain region responsible for self narrative the default mode network
drops markedly in activity
the result is less anxiety and less rumination
and weaker emotional reactions to negative events
this is not because you have gone numb
it is because the self narrative engine that kept amplifying the pain has quieted down a bit
so the theory Seth offers is not just an academic discussion
it points to a practical insight
since me was never a fixed entity that needs protecting
you do not have to clutch it so tightly
you can respond more flexibly
experience more openly
and face change more calmly
but there is a crack here that Seth never opened up
and it is worth thinking about
if perception is a controlled hallucination
and the self is a controlled hallucination too
then what is the thing that realizes all of this is a hallucination
is it a hallucination as well
if it is
then who is realizing that it is a hallucination
if it is not
then where does it come from
the theory Seth offers explains the contents of consciousness
that is what you experience
but the fact that there is experience at all
still seems to hide somewhere deeper
maybe the controlled hallucination theory is like a mirror
it lets you see your own face
but you can never use it to see the mirror itself
maybe this is exactly what makes consciousness research so fascinating
you are always using consciousness to study consciousness
like a hand trying to grab itself and lift itself up
what do you think
if the self is an illusion
then the thing that is thinking the self is an illusion
what is that
I am Leo Wang
see you next time