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If you’ve ever had a conversation with Siri
or Alexa or your Google Home,
it might seem like machines are just a couple
of steps away from being fully conscious beings;
things that actually experience the world.
But since we only have insight into our own
experiences,
humans are the only things we know are conscious.
And the fact that we are is one of the most
obvious things about us.
It’s part of what makes us human.
Even so, figuring out exactly what consciousness
is
and whether or not it could emerge in non-human
things has stumped us for centuries.
Scientists can’t even agree on whether or
not it’s possible
to study something that’s so personal using
the scientific method.
But some say that it’s not just possible,
it’s necessary.
A theory of consciousness could help us figure
out if a given coma patient is likely to recover.
It could influence the way we treat animals.
And it could even help us navigate our relationship
with technology.
So, since the 1980s, researchers have been
taking a crack at
figuring out consciousness from a scientific
perspective.
For now, we’re still nowhere near solving
it, but we have learned some things
about what a theory of consciousness might
eventually look like.
Except, first things first. We have a problem
with figuring out consciousness:
it’s that we have to define what it is.
It’s hard to put a finger on exactly what
it means.
For most purposes, you can think of consciousness
as the name for what it feels like to experience
the world,
rather than just interact with it through
inputs and outputs.
And, yes, every interaction starts with an
input.
The things we see and smell and hear in our
environment turn into electric signals
that travel through our brain, thanks to charged
atoms moving in and out of neurons.
But somehow, the movement of those atoms
can create the experience of hearing music
or smelling a rose.
And that experience? That is consciousness.
If you don’t see how that’s different
from
a robot responding to an input with an output,
think about this:
Your body responds to lots of stimuli without
your conscious involvement.
For example, food makes your mouth water,
and cold makes your hair stand up,
but you don’t have to be conscious of those
things for them to happen.
They just happen. Like a robot.
On the other hand, you’re conscious of the
way things smell or feel.
You’re aware of what it feels like to be
you.
And while your subconscious brain has countless
processes happening in parallel,
your conscious experience is a single stream
of events, almost like a story.
So you can think of consciousness as meaning
“experience” or “awareness.”
And scientists more or less agree up to that
point. The question is where to go from there.
The study of consciousness as a scientific
thing, as opposed to a philosophical one,
took off in the 1980s with Francis Crick,
a neuroscientist
and, yeah, you’ve probably heard this name,
co-discoverer of the double-helix structure
of DNA.
After he’d basically decoded life, he was
ready to take on what he saw as
the next big scientific mystery: consciousness.
And he recruited a bunch of young researchers
to get involved.
But Crick and his collaborators didn’t set
out
looking for the ultimate explanation of consciousness.
Instead, as a starting point, their goal was
to find the part of the brain that gave rise to it.
I mean, it wasn’t universally accepted that
consciousness began and ended with the brain,
and it still isn’t today, but that was most
people’s starting assumption.
This team called what they were looking for
the neural correlates of consciousness.
And over the past few decades, they and other
scientists have made some progress.
For instance, some research suggests that
conscious experience
is rooted in a part of the brain called the
posterior cortex.
But again, this is still a correlate of consciousness,
not a cause.
So even if they do manage to narrow down the
thing that gives rise to consciousness,
scientists still face the biggest question:
how.
In an attempt to get to the bottom of that,
two major ideas have emerged
about how we might study consciousness in
a scientific way;
that is, with testable hypotheses and measurable
results.
Neither one is an actual answer at this point,
but their goal is just to find ways to study
this subjective experience using rigorous science.
So, they may be off-base, but at the very
least,
they offer ways to approach the problem that
are scientifically testable.
The older of those ideas is called the Global
Workspace Theory.
It was developed by the neuroscientist Bernard
Baars,
and it’s been around in some form since
1982.
It suggests that there’s a network of cells
in your brain called a workspace
that’s at the root of your conscious experiences.
At any given time, you’ve got all kinds
of signals milling about in your brain,
but according to this theory, this workspace
is kind of like the fan cam of your brain.
Any signal that happens to be processed by
those cells
gets broadcast to the rest of your brain,
and you become conscious of it.
This workspace is really limited, though,
and it can only hold so much information at once.
Which could explain why information and ideas
drift in and out of your consciousness so easily.
Like, you might be fixated on an annoying
sound, and then forget all about it
as soon as someone involves you in an interesting
conversation.
What we don’t have is any proof that this
idea is correct,
but there is some preliminary evidence for
it.
For instance, in an experiment published in
2001, a team of researchers had
15 participants look at words flashed on screens
for 29 milliseconds each.
That is long enough for a word to become readable,
but in some cases,
the experimenters used a technique called
masking
to prevent the subjects from consciously registering
the word.
They did that by flashing another image after
the word,
which interrupted their conscious processing.
By imaging the participants' brains, the researchers
were able to see that
the words that remained subconscious only
produced a small amount of activity in the brain,
while the words that the participants became
conscious of
triggered a whole flurry of activity in many
different regions.
This wasn’t necessarily proof of the Global
Workspace Theory,
but it did give the experimenters a clear
picture of the brain areas
involved in subconscious and conscious processing
of the same signal.
And in later research, scientists have used
that as a starting point
to try and figure out how messages that pass
through this network
might get broadcast to the rest of the brain.
It is still far from a solution to consciousness,
but this theory does a few things well.
For one, by suggesting that conscious processing
is limited to a specific network,
it offers a possible explanation for why
our conscious brain is only capable of narrow
streams of thought,
even though our brains can subconsciously
process so many things in parallel.
But more importantly, the fact that it involved
questions that were testable
gives us a way to study consciousness using
the scientific method!
The theory still has its sticking points,
though.
Like, it goes one step further than the neural
correlates of consciousness,
but it still doesn’t provide the ultimate
how.
And then, there’s also some resistance to
the idea that consciousness is computational;
that it just comes about because of the way
the brain is hooked up.
Because if that’s true, it suggests that,
in theory,
there’s nothing keeping machines from gaining
consciousness;
that it’s all a question of having the right
wiring.
And that would open up a whole different can
of ethical worms.
But it is a testable hypothesis. And in science,
that counts for a lot.
This isn’t the only hypothesis out there,
though,
and others take a totally different approach.
For example, in 2004, the neuroscientist Giulio
Tononi proposed
what he called Integrated Information Theory,
or IIT.
Since it’s impossible to scientifically
observe someone’s personal, conscious experience,
even if we can see some of what it looks like
in the brain,
Tononi crafted his theory by working backwards
from the few things that seem to be universally
true about consciousness.
For one, we know that it’s subjective,
meaning that you are the only person having
your conscious experience.
No one else can step in and experience what
the world is like for you.
Second, we know that the experience of consciousness
is “unified,”
meaning it can’t be split into pieces.
Like, you are one thing; you cannot willfully
split your sense of self into two selves.
You also can’t, say, decide to only process
certain kinds of information.
You can’t wake up tomorrow and decide you’re
only gonna see the color blue,
or only smell nice things.
Although I think that would be a handy skill.
Tononi took these observations as starting
points, along with the assumption that
consciousness somehow comes from our web of
interconnected neurons.
Then he proposed that consciousness comes
from
the amount of interconnectedness in a system,
or, in his words, the amount of integrated
information.
IIT suggests that, essentially, the whole
of all your neurons working together
amounts to more than the sum of its parts.
So, connected neurons can create an experience
that individual ones cannot.
Again, not everyone is on board with this
idea, and testing is still in an early stage.
But researchers have done some preliminary
experiments that compare
the amount of connectivity in a brain to a
person’s level of consciousness.
For example, in one study, Tononi and his
collaborators rounded up 11 volunteers
and used a magnetic pulse to deliver a burst
of stimulation to neurons in their brains.
Then, they used sensors on the scalp to measure
the amount of activity that pulse produced.
Next, they sedated the subjects and performed
the same experiment.
The second time around, the pulse produced
much less activity,
suggesting that there were fewer connections
between neurons,
so that triggering one group of them
didn’t set off the same chain reaction that
it had the first time around.
It’s still not possible to directly measure
the amount of connectivity in the human brain,
but experiments like this can serve as a decent
proxy;
a way of figuring out if there really is a
link between integration and consciousness.
If there is, that implies that consciousness
exists on a spectrum.
And when you play this theory out,
it implies that not only could machines become
conscious,
but everything with any amount of interconnected
information,
from a wasp to the internet, might already
be a little bit conscious.
Like the Global Workspace Theory, IIT doesn’t
yet provide
any kind of satisfying answer to the problem
of consciousness,
and the consequences also seriously challenge
things
we instinctively believe to be true about
the world.
So if it’s true, we might have to think
a little harder about how we interact with things.
Still, the idea of measuring interconnectedness
provides a path for exploring consciousness
scientifically.
And, like with the Global Workspace Theory,
that is what makes this idea stand out.
These hypotheses are still works in progress,
but if either one proves true,
it could help us figure what has consciousness
and what does not.
Like, if IIT is right, measuring the amount
of interconnectedness in a brain
could help doctors and scientists decide how
conscious a coma patient is.
Or it could help future computer scientists
answer those same questions
about artificial intelligence programs.
On the other hand, if the Global Workspace
Theory ends up being right,
and if scientists can identify that workspace,
the fancam of the brain,
doctors could look for activity in that region
to see if a patient has any signs of consciousness.
So far, neither one of those ideas is developed
enough to be useful in any practical sense,
so for now, there’s no foolproof way to
identify consciousness.
And until we understand how it arises,
we probably won’t be able to say what has
it or not, either.
But the fact that we are conscious means we’re
going to keep being curious,
and scientists are gonna keep looking, as
long as the problem is unsolved.
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