36 | New Scientist | 22 June 2019
“ If our brain is
a smartphone,
consciousness
is the screen”
Think of the conscious mind as a furnace.
If you are deeply asleep, the flame of
consciousness has died down to a low but
persistent level. In REM sleep, when you dream,
the flame is jumping and burning brightly but
erratically. In a coma, it is a glowing ember.
Consciousness, in other words, exists in a
range of states. One explanation for this is that
full consciousness erupts when many parts of
the brain broadcast information to a network
of neurons known as the global workspace.
When this broadcast doesn’t take place,
sensations remain subconscious. When the
broadcast is incomplete, you get different
levels of consciousness, such as when you are
dreaming or have had a blow to the head.
By studying these states, we should one day
be able to pinpoint the brain mechanisms that
give rise to consciousness. So why then, has
explaining consciousness – how a kilogram
or so of nerve cells conjures up the swirl of
thoughts and emotions that make up our
mental experience – been dubbed “the hard
problem”? One reason is that philosophers
have focused on explaining how we become
aware of experiences. Their term “qualia”
describes the properties of experiences we
have, such as the redness of a strawberry or
the perception of the taste of wine. Trying to
find explanations for qualia has caused no
end of confusion among neuroscientists.
One solution to the problem is to ignore
it. “ ‘Qualia’ is a term of art, introduced by
philosophers who want to make the questions
about the nature of consciousness answerable
only by spooky, non-biological accounts,”
says Patricia Churchland at the University
of California, San Diego. After all, we don’t
normally talk about our qualia, we talk about
things such as being tired, needing to eat
or even being in love – feelings that have a
straightforward, non-spooky biological origin.
Most people aren’t aware of their qualia
until they are prompted by philosophers,
says Daniel Dennett of Tufts University,
Massachusetts. Dennett not only thinks
that there is no hard problem, he believes
consciousness itself is a kind of illusion.
“It takes some substantial coaxing and cajoling
to get people to ‘notice’ their qualia,” he says,
“and when they think they do notice them,
they are falling for another illusion.”
The illusion, according to Dennett, is this:
each of us believes that we have privileged
access to some remarkable properties of
our own mental states, with which we are
intimately acquainted and which we perceiveas experiences. But the brain presents to
our consciousness only what matters to us,
and does so in a way we can understand. For
example, it is why we see things as being a
particular colour. The real world isn’t like that,
but our visual systems effectively colour-code
the world for us, to simplify it.Illusions of the mind
Dennett argues that much as colour is
an illusion created by the brain, so too is
consciousness. “Consciousness is a user
illusion designed by evolution to make life
easier for the brain that must guide a body
through a perilous life,” he says.
Smartphone designers call the screen of
a phone a user illusion. The screen is the
interface to the computer underneath, but the
icons on it – such as the envelope that depicts
a message – are symbolic, and don’t bear any
relation to the actual hardware and software of
the phone’s messaging system. If our brain is a
smartphone, consciousness is the screen, our
interface to the brain. However, as Churchlandsays, the metaphor isn’t exact. When we feel
dizzy or pinpoint where a sound is coming
from, for example, it is the result of physical
processes in the brain. Perhaps consciousness
is more like a smartphone screen that presents
different apps according to the amount of
battery left or how much it has been shaken.
Consciousness, in other words, is a partial
illusion, a picture knitted together by the brain
as a result of all the inputs it is receiving and
the completeness of the brain broadcast.
Rowan HooperWhat is consciousness?
Neural
ripples
Gamma waves
are one of
five types of
brainwave,
each oscillating
at different
frequencies and
associated with
different tasks.
The others are
alpha, beta,
delta and theta
wavesWhen we
consciously
pay attention
to something,
what is going
on in the brain?Gamma brainwavesPL
AINPICTURE
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