297 lines
15 KiB
Markdown
297 lines
15 KiB
Markdown
---
|
||
created_at: '2015-05-28T20:37:10.000Z'
|
||
title: 'The Grand Illusion: Why consciousness exists only when you look for it (2002)'
|
||
url: http://www.susanblackmore.co.uk/journalism/ns02.htm
|
||
author: monort
|
||
points: 52
|
||
story_text:
|
||
comment_text:
|
||
num_comments: 45
|
||
story_id:
|
||
story_title:
|
||
story_url:
|
||
parent_id:
|
||
created_at_i: 1432845430
|
||
_tags:
|
||
- story
|
||
- author_monort
|
||
- story_9621011
|
||
objectID: '9621011'
|
||
year: 2002
|
||
|
||
---
|
||
**The Grand Illusion:**
|
||
**Why consciousness exists only when you look for it**
|
||
|
||
New Scientist, 22 June 2002, p 26-29
|
||
|
||
“The last great mystery of science”; “the most baffling problem in the
|
||
science of the mind”; this is how scientists talk about consciousness,
|
||
but what if our conscious experience is all a grand illusion?
|
||
|
||
Like most people, I used to think of my conscious life as like a stream
|
||
of experiences, passing through my mind, one after another. But now I’m
|
||
starting to wonder, is consciousness really like this? Could this
|
||
apparently innocent assumption be the reason we find consciousness so
|
||
baffling?
|
||
|
||
Different strands of research on the senses over the past decade suggest
|
||
that the brave cognitive scientists, psychologists and neuroscientists
|
||
who dare to tackle the problem of consciousness are chasing after the
|
||
wrong thing. If consciousness seems to be a continuous stream of rich
|
||
and detailed sights, sounds, feelings and thoughts, then I suggest this
|
||
is the illusion.
|
||
|
||
First we must be clear what is meant by the term “illusion”. To say that
|
||
consciousness is an illusion is not to say that it doesn’t exist, but
|
||
that it is not what it seems to be―more like a mirage or a visual
|
||
illusion. And if consciousness is not what it seems, no wonder it’s
|
||
proving such a mystery.
|
||
|
||
For the proposal “It’s all an illusion” even to be worth considering,
|
||
the problem has to be serious. And it is. We can’t even begin to explain
|
||
consciousness. Take this magazine in front of your eyes. Right now, you
|
||
are presumably having a conscious experience of seeing the paper, the
|
||
words, and the pictures. The way you see the page is unique to you, and
|
||
no one else can know exactly what it is like for you. This is how
|
||
consciousness is defined: it is your own subjective experience.
|
||
|
||
But how do you get from a magazine composed of atoms and molecules, to
|
||
your experience of seeing it? Real, physical objects and private
|
||
experiences are such completely different kinds of thing. How can one be
|
||
related to the other? David Chalmers, of the University of Tucson,
|
||
Arizona, calls it the “Hard Problem”. How can the firing of brain cells
|
||
produce subjective experience? It seems like magic; water into wine.
|
||
|
||
If you are not yet feeling perplexed (in which case I am not doing my
|
||
job properly), consider another problem. It seems that most of what goes
|
||
on in the brain is not conscious. For example, we can consciously hear a
|
||
song on the car radio, while we are not necessarily conscious of all the
|
||
things we do as we’re driving. This leads us to make a fundamental
|
||
distinction: contrasting conscious brain processes with unconscious
|
||
ones. But no one can explain what the difference really is. Is there a
|
||
special place in the brain where unconscious things are made conscious?
|
||
Are some brain cells endowed with an extra magic something that makes
|
||
what goes on in them subjective? This doesn’t make sense. Yet most
|
||
theories of consciousness assume that there must be such a difference,
|
||
and then get stuck trying to explain or investigate it.
|
||
|
||
For example, in the currently popular “Global Workspace” theory, Bernard
|
||
Baars, of the Wright Institute in Berkeley, California, equates the
|
||
contents of consciousness with the contents of working memory. But how
|
||
does being “in” memory turn electrical impulses into personal
|
||
experiences?
|
||
|
||
Another popular line of research is to search for the “neural
|
||
correlates” of consciousness. Nobel Laureate, Francis Crick, wants to
|
||
pin down the brain activity that corresponds to “the vivid picture of
|
||
the world we see in front of our eyes”. And Oxford pharmacologist, Susan
|
||
Greenfield, is looking for “the particular physical state of the brain
|
||
that always accompanies a subjective feeling” (New Scientist, 2 Feb, p
|
||
30). These researchers are not alone in their search. But their attempts
|
||
all founder on exactly the same mystery―how can some kinds of brain
|
||
activity be “in” the conscious stream, while others are not? I can’t see
|
||
what this difference could possibly be.
|
||
|
||
Could the problem be so serious that we need to start again at the very
|
||
beginning? Could it be that, after all, there is no stream of
|
||
consciousness; no movie in the brain; no picture of the world we see in
|
||
front of our eyes? Could all this be just a grand illusion?
|
||
|
||
You might want to protest. You may be absolutely sure that you do have
|
||
such a stream of conscious experiences. But perhaps you have noticed
|
||
this intriguing little oddity. Imagine you are reading this magazine
|
||
when suddenly you realise that the clock is striking. You hadn’t noticed
|
||
it before, but now that you have, you know that the clock has struck
|
||
four times already, and you can go on counting. What is happening here?
|
||
Were the first three “dongs” really unconscious and have now been pulled
|
||
out of memory and put in the stream of consciousness? If so were the
|
||
contents of the stream changed retrospectively to seem as though you
|
||
heard them at the time? Or what? You might think up some other
|
||
elaborations to make sense of it but they are unlikely to be either
|
||
simple or convincing.
|
||
|
||
A similar problem is apparent with listening to speech. You need to hear
|
||
several syllables before the meaning of a sentence becomes unambiguous.
|
||
So what was in the stream of consciousness after one syllable? Did it
|
||
switch from gobbledegook to words half way through? It doesn’t feel like
|
||
that. It feels as though you heard a meaningful sentence as it went
|
||
along. But that is impossible.
|
||
|
||
#### The running tap of time
|
||
|
||
Consciousness also does funny things with time. A good example is the
|
||
“cutaneous rabbit”. If a person’s arm is tapped rapidly, say five
|
||
times at the wrist, then twice near the elbow and finally three times on
|
||
the upper arm, they report not a series of separate taps coming in
|
||
groups, but a continuous series moving upwards―as though a little
|
||
creature were running up their arm. We might ask how taps two to four
|
||
came to be experienced some way up the forearm when the next tap in the
|
||
series had not happened yet. How did the brain know where the next tap
|
||
was going to fall?
|
||
|
||
You might try to explain it by saying that the stream of consciousness
|
||
lags a little behind, just in case more taps are coming. Or perhaps,
|
||
when the elbow tap comes, the brain runs back in time and changes the
|
||
contents of consciousness. If so, what was really in consciousness when
|
||
the third tap happened? The problem arises only if we think that things
|
||
must always be either “in” or “out” of consciousness. Perhaps, if this
|
||
apparently natural distinction is causing so much trouble, we should
|
||
abandon it.
|
||
|
||
Even deeper troubles threaten our sense of conscious vision. You might
|
||
be utterly convinced that right now you’re seeing a vivid and detailed
|
||
picture of the world in front of your eyes, and no one can tell you
|
||
otherwise. Consider, then, a few experiments.
|
||
|
||
The most challenging are studies of “change blindness” (New Scientist,
|
||
18 Nov 2000, p 28). Imagine you are asked to look at the left hand
|
||
picture in the
|
||
[illustration](https://www.susanblackmore.co.uk/journalism/change-blindness/)
|
||
below. Then at the exact moment you move your eyes (which you do several
|
||
times a second) the picture is swapped for the one on the right. Would
|
||
you notice the difference? Most people assume that they would. But
|
||
they’d be wrong. When our eyes are still we detect changes easily, but
|
||
when a change happens during an eye movement or a blink we are change
|
||
blind.
|
||
|
||
Another way to reveal change blindness is to present the two pictures
|
||
one after the other repeatedly on a computer screen with flashes of grey
|
||
in between (for an example see
|
||
http://nivea.psycho.univ-paris5.fr/ASSChtml/kayakflick.gif). It can take
|
||
people many minutes to detect even a large object that changes colour,
|
||
or one that disappears altogether, even if it’s right in the middle of
|
||
the picture.
|
||
|
||
What do these odd findings mean? At the very least they challenge the
|
||
textbook description that vision is a process of building up
|
||
representations in our heads of the world around us. The idea is that as
|
||
we move our eyes about, we build up an even better picture, and this
|
||
picture is what we consciously see. But these experiments show that this
|
||
way of thinking about vision has to be false. If we had such a picture
|
||
in our heads we would surely notice that something had changed, yet we
|
||
don’t. We jump to the conclusion that we’re seeing a continuous,
|
||
detailed and rich picture. But this is an illusion.
|
||
|
||
Researchers differ in how far they think the illusion goes.
|
||
Psychologists Daniel Simons of Harvard University and Daniel Levin of
|
||
Kent State University, Ohio, suggest that during each visual fixation
|
||
our brain builds a fleeting representation of the scene. It then
|
||
extracts the gist and throws away all the details. This gives us the
|
||
feeling of continuity and richness without too much overload.
|
||
|
||
Ronald Rensink of the University of British Columbia in Vancouver, goes
|
||
a little further and claims that we never form representations of the
|
||
whole scene at all, not even during fixations. Instead we construct what
|
||
he calls “virtual representations” of just the object we are paying
|
||
attention to. Nothing else is represented in our heads, but we get the
|
||
impression that everything is there because a new object can always be
|
||
made “just in time” whenever we look.
|
||
|
||
Finally, our ordinary notions of seeing are more or less demolished by
|
||
psychologists Kevin O’Regan of the CNRS, the French national research
|
||
agency in Paris, and Alva Noë of the University of California, Santa
|
||
Cruz, who first described vision as a grand illusion. They argue that we
|
||
don’t need internal representations at all because the world is always
|
||
there to be referred to. According to their “sensorimotor theory of
|
||
vision” seeing is not about building pictures of the world in our heads,
|
||
it’s about what you are doing. Seeing is a way of interacting with the
|
||
world, a kind of action. What remains between eye movements is not a
|
||
picture of the world but the information needed for further exploration.
|
||
The theory is dramatically different from existing theories of
|
||
perception.
|
||
|
||
It’s not clear who’s right. Perhaps all these theories are off the mark,
|
||
but there is no doubt about the basic phenomenon and its main
|
||
implication. Searching for the neural correlates of the detailed,
|
||
picture in our heads is doomed because there is no such picture.
|
||
|
||
This leaves another problem. If we have no picture, how can we act on
|
||
the things we see? This question may seem reasonable but it hides
|
||
another false assumption―that we have to see consciously in order to
|
||
act. We need only think of the tennis player who returns a serve before
|
||
consciously seeing it, to realise that this is false, but the situation
|
||
is odder than this. We probably have several separate visual systems
|
||
that do their jobs somewhat independently, rather than one single one
|
||
that produces a unified visual world.
|
||
|
||
David Milner of the University of St Andrews, and Melvyn Goodale of the
|
||
University of Western Ontario, argue that there is one system for fast
|
||
visuomotor control and a slower system for perceiving objects. Much of
|
||
their evidence comes from patients with brain damage, such as D.F. who
|
||
has a condition known as visual form agnosia. She cannot recognise
|
||
objects by sight, name simple line drawings, or recognise or copy
|
||
letters, even though she produces letters correctly from dictation and
|
||
can recognise objects by touch. She can also reach out and grasp
|
||
everyday objects (objects that she cannot recognise) with remarkable
|
||
accuracy. D.F. seems to have a visual system that guides her actions but
|
||
her perception system is damaged.
|
||
|
||
In a revealing experiment D.F. was shown a slot set randomly at
|
||
different angles. (Trends in Neurosciences, vol 15 p 20, 1992). She
|
||
could not consciously see the orientation of the slot, and could not
|
||
draw it or adjust a line to the same angle. But when given a piece of
|
||
card she could quickly and accurately line it up and post it straight
|
||
through. Experiments with normal volunteers have shown similar kinds of
|
||
dissociation, suggesting that we all have at least two separate vision
|
||
systems.
|
||
|
||
Perhaps the most obvious conclusion is that the slow perceptual system
|
||
is conscious and the fast action system is unconscious. But then the old
|
||
mystery is back. We would have to explain the difference between
|
||
conscious and unconscious systems. Is there a magic ingredient in one?
|
||
Does neural information turn into subjective experiences just because it
|
||
is processed more slowly?
|
||
|
||
Perhaps the answer here is to admit that there is no stream of conscious
|
||
experiences on which we act. Instead, at any time a whole lot of
|
||
different things are going on in our brain at once. None of these things
|
||
is either “in” or “out” of consciousness but every so often, something
|
||
happens to create what seems to have been a unified conscious stream; an
|
||
illusion of richness and continuity.
|
||
|
||
It sounds bizarre, but try to catch yourself not being conscious. More
|
||
than a hundred years ago the psychologist William James likened
|
||
introspective analysis to “trying to turn up the gas quickly enough to
|
||
see how the darkness looks.” The modern equivalent is looking in the
|
||
fridge to see whether the light is always on. However quickly you open
|
||
the door, you can never catch it out. The same is true of consciousness.
|
||
Whenever you ask yourself, “Am I conscious now?” you always are.
|
||
|
||
But perhaps there is only something there when you ask. Maybe each time
|
||
you probe, a retrospective story is concocted about what was in the
|
||
stream of consciousness a moment before, together with a “self” who was
|
||
apparently experiencing it. Of course there was neither a conscious self
|
||
nor a stream, but it now seems as though there was.
|
||
|
||
Perhaps a new story is concocted whenever you bother to look. When we
|
||
ask ourselves about it, it would seem as though there’s a stream of
|
||
consciousness going on. When we don’t bother to ask, or to look, it
|
||
doesn’t, but then we don’t notice so it doesn’t matter.
|
||
|
||
Admitting that it’s all an illusion does not solve the problem of
|
||
consciousness but changes it completely. Instead of asking how neural
|
||
impulses turn into conscious experiences, we must ask how the grand
|
||
illusion gets constructed. This will prove no easy task, but unlike
|
||
solving the Hard Problem it may at least be possible.
|
||
|
||
**Susan Blackmore is a psychologist, writer and lecturer based in
|
||
Bristol.**
|
||
|
||
**Further Reading**
|
||
|
||
Consciousness Explained by Daniel Dennett, Penguin (1993)
|
||
|
||
O’Regan and Noë’s ideas will soon be debated in a special issue of
|
||
Behavioral and Brain Sciences.
|
||
|
||
N.B. The current issue of Journal of Consciousness Studies is devoted to
|
||
the Grand Illusion. See <http://www.imprint.co.uk/jcs/>
|
||
|
||
This will also be published as a book Is the Visual World a Grand
|
||
Illusion? Ed. Alva Noë, Imprint Academic, 2002.
|
||
|
||
Watch me talking about [the grand
|
||
illusion](http://video.google.com/videoplay?docid=6958873142520847424&ei=p9E3Ss_UN4Xt-AaKx5Fz&q=sue+blackmore+2005+skeptics&hl=en&client=firefox-a)
|
||
at the Skeptics’ Conference 2005
|