34 | New Scientist | 21 September 2019Other researchers build on the insight that
consciousness isn’t just a stimulus processed
in the brain. Their higher-order thought theory
proposes that the brain contains a system that
re-represents the stimulus at a higher level
with added self-information, which is how we
become conscious of it. Exactly what that
higher-order information is, what cognitive
purpose it serves and where in the brain it is
constructed are all debated – although some
people associate it with the prefrontal cortex.
A particularly influential idea is known as
global workspace theory. Here, information
coming both from outside and within the
brain competes for attention. Information
that wins this competition becomes globally
accessible by systems throughout the brain
so that we become aware of it and are able to
process it deeply. Also popular is the integrated
information theory. It sees consciousness as
an emergent property of complex systems
and posits that the amount of consciousness
in any system can be measured in units
called phi. Phi is high in the human brain, but
also present in everything from a hamburger
to the universe, since everything contains
at least some integrated information.
Then there is the idea that consciousness
is an illusion. This is often misinterpreted. It
doesn’t mean that consciousness doesn’t exist,
or that we are fooled into thinking we have it.
Instead, it likens consciousness to the illusion
created for the user of a human-computer
interface and argues that the metaphysical
properties we attribute to ourselves areWhat is
consciousness?
A new idea about what consciousness is and
why we have it reveals how we could recreate it,
says neuroscientist Michael Graziano
C
ONSCIOUSNESS is a slippery concept.
It isn’t just the stuff in your head.
It is the subjective experience of some
of that stuff. When you stub your toe, your
brain doesn’t merely process information
and trigger a reaction: you have a feeling of
pain. When you are happy, you experience
joy. The ethereal nature of experience is the
mystery at the heart of consciousness. How
does the brain, a physical object, generate a
non-physical essence?
This experience-ness explains why pinning
down consciousness has been described as
“the hard problem”. Subjective experience
doesn’t exist in any physical dimension.
You can’t push it and measure a reaction
force, scratch it and measure its hardness
or put it on a scale and measure its weight.
Philosophers have described it as the “ghost
in the machine”. Even scientific ideas about
consciousness often have an aura of the
metaphysical. Many scientists describe it as an
illusion, while others see it as so fundamental
that it doesn’t have an explanation. Always at
the centre of the riddle lies its non-physicality.
But what if consciousness isn’t so mystical
after all? Perhaps we have just been asking
the wrong question. Instead of trying to
grapple with the hard problem, my colleagues
and I at Princeton University take a more
down-to-earth approach. My background lies
in the neuroscience of movement control,
what you could call the robotics of the brain.
Drawing on that, I suggest that consciousness
can be understood best from an engineeringperspective. Far from being some sort of
magical property, it is a tool of extraordinary
power. It is a tool that can be engineered into
machines. Our new approach shows how.
Because the normal methods of observation
and measurement don’t quite apply, the study
of consciousness has always sat uneasily in
mainstream science. A few decades ago,
The International Dictionary of Psychology
described consciousness as “a fascinating
but elusive phenomenon; it is impossible to
specify what it is, what it does or why it evolved.
Nothing worth reading has ever been written
about it.” Since then, consciousness has
become an increasingly popular topic in
science, generating numerous ideas and
thousands of papers but very little agreement.
One approach searches for the neural
correlates of consciousness: the minimal
physical signature in the brain needed for
subjective experience. There have been some
interesting leads, but the hunt continues.OSKA >
Features Cover story
“ Far from being
some sort of
magical property,
consciousness is
a tool of great,
practical power”