[tt] spiked review of books: We're no slaves to our senses

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We're no slaves to our senses
http://www.spiked-online.com/index.php?/site/reviewofbooks_article/3760/
7.8.24
[Linked by Arts & Letters Daily.]

Free will and agency are not merely the creation of nerve endings
in the human brain. So while neuroscience can tell us a lot, it
does not hold the key to understanding human uniqueness.
Stuart Derbyshire

Twenty years ago, a new technique for directly investigating brain
activity, called positron emission tomography (PET), became
available.

PET involves the injection of a radioactive isotope that rapidly
decays in the bloodstream of the volunteer (1). As the isotope
decays it causes the emission of energy, which can be detected
outside the body, and as the brain requires blood for energy, areas
that are more active receive more blood and thus more energy is
detected from those areas. Therefore, using this technique, a
picture of what the brain is doing when somebody thinks, acts or
feels can be built.

By chance I was able to take part in a PET project as part of my
undergraduate research and then pursue that work for my PhD (2).
There was a considerable buzz about the possibilities afforded by
direct access to brain function and it was widely expected that the
major psychiatric disorders- schizophrenia, chronic depression,
obsessive disorders, autism and many more - would soon be resolved
using these techniques. Although PET and, more recently, fMRI have
provided many new insights and theories, breakthroughs in treatment
for the major psychiatric disorders remain notably absent (3).

There are two major reasons for the lack of new treatment. The
first is that although technologies to directly represent brain
function are exciting and visually compelling, they still only
provide a limited amount of detail. Imagine trying to figure out
what is happening inside the Empire State Building by watching the
lights go on and off. You might get some idea as to the internal
function, but not much. Now imagine that you can change the pattern
of lights by setting off sirens outside, directing heat at the
building or sending somebody inside with a chocolate cake. You
might, through careful observation, be able to work out those areas
of the building that have good sound-proofing or air conditioning
and where the kitchens are located. But your knowledge of what is
happening inside will always be limited by your method of
investigation.

The same problem faces those of us who hope to understand brain
function. The things that we can measure (blood flow in the brain,
the electrical and magnetic output of the brain, neurochemical
concentrations in the brain, and so forth) are just too simple. We
need more knowledge and more detail before we can possibly
understand what is happening inside. These limitations explain at
least some of the frustrations in trying to advance psychiatry and
likely explain the lack of advance in understanding at least some
specific disorders.

But there is a further reason why our understanding is lagging
behind expectation. The facts provided by brain imaging, and other
associated brain-based investigations, are the wrong sorts of
facts. Neuroscience provides the wrong sort of knowledge to answer
at least some of the questions we are asking about psychiatric
illness.

Professor Chris Frith, as he describes in his new book Making up
the Mind: How the Brain Creates our Mental World, has dedicated
much of his academic career to the study of schizophrenia.
Schizophrenia is a highly complex psychiatric disorder where the
person suffers from, amongst other things, distorted thinking,
hallucinations, and a reduced ability to feel normal emotions.

As Frith explains: `There are no objective physical signs of
schizophrenia. The diagnosis is based on what the patient tells the
doctor. Patients say that they hear voices when no one is there
(false perceptions - hallucinations). Patients describe how they
are persecuted by their colleagues at work when there is no
evidence that this is the case (false beliefs - delusions).
Patients with hallucinations and delusions are sometimes described
as being out of touch with reality. But it is the mental world,
rather than the physical world, that they have lost touch with.'

Not unreasonably, Frith describes schizophrenia as the consequence
of some damage to brain function, damage that we don't yet fully
understand. He makes the very plausible case that if we can
understand how mental function comes about in people without
schizophrenia we will be better placed to understand how mental
function goes so terribly wrong in people with schizophrenia. This
draws Frith, and the reader, on to difficult terrain where
questions such as `what is perception?', `how do we form beliefs?'
and `how do we will?' must be answered.

Frith's general thesis is that all these questions can be answered
by understanding how the brain works, and he begins by pointing out
that normal brains do all kinds of things without us being aware of
it. Toss a ball up into the air and catch it, for example, and your
brain will perform multiple differential equations that you will
never be aware of. The calculations and assumptions that our brains
make can cause us to make mistakes such as in the Muller-Lyer
illusion illustrated below.

In this illusion the lines appear to be different lengths, but, in
fact, the lines are all identical in length (get out a ruler if you
don't believe me). Even when you know that the lines are the same
length your brain will continue to tell you that they are
different. This is an everyday hallucination created by the hidden
assumptions your brain makes about how the world is organised. The
illusion occurs because the visual-system processes that judge
depth and distance assume that the `angles in' configuration
corresponds to an object that is closer, and the `angles out'
configuration corresponds to an object that is far away. Because
the lines are actually the same size, the one that is perceived as
being farther away is experienced as being larger than the one
perceived as being closer.

An obvious question is, `why do our brains do that?' Frith explains
that our brains make assumptions because sensation is simply too
ambiguous and if we were always processing sensation we would have
no time for anything more interesting: `Couldn't the system be
tuned so that the sensory signals always dominated our experience?
Then hallucinations could not occur. In fact, this is a bad idea,
for many reasons. Sensory signals are simply too unreliable. But
more importantly, such domination would make us slaves to our
senses.'

Descartes explained long ago that while the mind is clearly exposed
to sensory information, it is not drowned or dissolved by the
senses (4). Human beings are self-located within sensory
experience, but we are not sensorily immersed; our intuition of
ourselves as particular things with particular location and
experience is opened up by, rather than collapsed into, our senses.

At first glance, the fact that our brain filters and constrains
what we can see is a challenge to the notions of reality and free
will. After all, if our brain has already decided what we are going
to perceive, then in what sense can we perceive the world as it
truly is? And if our brain is making decisions for us, in what
sense can we act on the world according to our own free will?
Consequently Frith argues that what we see is not the world as it
truly is, but an illusion: `Even if all our senses are intact and
our brain is functioning normally, we do not have direct access to
the physical world. It may feel as if we have direct access, but
this is an illusion created by our brain.'

And he expresses considerable ambivalence regarding the nature of
our conscious minds and the possibility of free will. `I am a
materialist', he writes. `But I admit that sometimes I sound like a
dualist.... On the other hand I am firmly convinced that I am a
product of my brain, as is the awareness that accompanies me.' He
also says, `My beliefs on free will are very ambivalent. What I do
know is that I have a very strong experience of free will'.

Frith's dual contentions that reality is illusory and free will is
just a manufactured state of mind are both far too strong. Our
limited direct access to the world `as it truly is' is certainly a
real problem. It is a problem because the world does not divide
itself into fact-sized chunks that can be consumed by our senses.
Whether a forest is perceived as a unit or an aggregation of many
trees is arbitrary, just as it is arbitrary whether we observe
leaves as independent or continuous with twigs and whether the
twigs are independent or continuous and so on ad infinitum. Nature
does not inherently divide itself into salient pieces, and what is
salient or important is only revealed in the relationships within
nature. Cows, for example, endow grass with the character of food
because of the relationship between cows and grass - namely the
consumption of the latter by the former. And it is in the character
of cows to recognise grass as a source of nourishment.

Similarly, it is only through our relationship with the world that
we can come to divide the world and begin to describe it. The facts
that we can lay claim to about the world are arbitrary in so far as
they are selected from an almost infinite number of potential
facts, but we can, nevertheless, have great confidence that the
facts we are gathering are real. We can have this confidence
because our actions based upon those facts generally lead to
expected outcomes - trains move forward through space, telephones
transmit recognisable voice signals, medical intervention saves
lives, and so on. These happy outcomes indicate that our division
of the world is grounded in reality and that although our facts are
arbitrarily selected we are not making them up as we go along.

In short, Frith misses, or understates, the role of inquiry in
constructing a real representation of the world. Inquiry brings
human beings into an understanding of the world that continues to
more closely approximate the way the world truly is. The
constraints that our brain places upon inquiry do not dictate
reality but rather allow us the freedom to interrogate reality.
Just imagine, as Descartes did, that we can be liberated from the
constraint of the body and exist only as pure thought. What greater
freedom could one possibly enjoy? No longer bound by space or time,
such a being would be free to traverse the universe at will. Except
that such an undifferentiated and locationless being, no longer
tensed in time, would be unable to separate past, present and
future or to separate here from there. With no fixed abode in time
or space there would be no means by which experience could be
determinate and no features to discriminate the specific from the
general. It is precisely the constraint of a body, existing in the
here and now, which enables a specific viewpoint to flourish and an
independent existence to announce itself (5).

Constraint upon our embodied action is also necessary for free
will. If every action were driven by conscious agency then we would
be overwhelmed by the effort of trying to control all the relevant
parameters with the requisite precision just as our senses would be
drowned by information if there were no filtering. Constraint is
necessary to allow coherent goal-directed behaviour and coherent
percepts (6, 7). At the same time, however, we cannot be
downloading a fixed set of responses or experiencing a fixed set of
percepts because our behaviour would not contain the flexibility
that we have evidently wielded to construct trains,
telecommunication, modern medicine and so forth. In sum, our
behaviour is both constrained and indeterminate, where constrained
most certainly does not mean controlled and indeterminate most
certainly does not mean random.

The negotiation of constraint and indeterminacy is not substantive;
it cannot be located in parts of the brain, boiled down and
recorded on a graph. That negotiation is an active, lived process
and free will is possible because of the uniquely human ability to
interrogate nature. Early human mentality would have resided in the
ability to put oneself into a relationship with the environment so
as to call out specific stimuli such as food or warmth.
Importantly, this is no longer a relationship that is dictated by
anatomy or evolutionary instinct, but rather is one that is,
minimally at first, breaking free from the pre-ordained
possibilities provided by evolutionary history. This new
relationship to the character of things calls upon a sentience that
is inside the organism, but the entire process is not a purely
mental product that can be located in the brain. This early
mentality is that relationship of the organism to stimuli in the
environment that are set free by exploration to address specific
biological needs. Within that relationship, constrained by
circumstance, constrained by the biological imperatives of survival
and reproduction, and constrained by historical development,
freedom and agency begin. This is quite different from the
engagement with stimuli driven by programmed behaviours and fully
constrained by anatomical limitations. For early humans, there is a
transformation from stimulus-response behaviour to inquiry.

The fundamental mistake that Frith makes - and this is a common
error - is to believe that agency or free will are products only of
the human brain. The brain is necessary but it is not sufficient,
and chasing agency into the brain will only yield disappointment
or, in this case, a sense that agency is illusory. If agency is not
merely a product of ordinary brains, then it follows that abnormal
brains might not be the whole or only answer when there are
psychiatric problems and delusions of agency such as in
schizophrenia.

To his tremendous credit, Frith is ready to push neuroscience past
the hype that can be generated by a pretty picture and into a
deeper understanding of what makes mental function. For that alone,
Making up the Mind should be read by anyone interested in
understanding contemporary neuroscience. The idea, however, that
the brain constructs the mind is incomplete, and the quicker we
realise that, the quicker we will make progress in understanding
both normal and abnormal minds.

Stuart Derbyshire is a senior lecturer in psychology at the
University of Birmingham, England, and director of pain research at
the Birmingham University Imaging Centre.

Making up the Mind: How the Brain Creates our Mental World by
Professor Chris Frith is published by Blackwell Publishing. (Buy
this book from Amazon(UK).)

(1) PET scanning utilizes biological molecules synthesized with
radiolabeled isotopes, such as 15O-labeled water, created in a
cyclotron. The 15O-labeled water stabilises by emitting a
positively charged electron (or positron, hence positron emission
tomography). Once the positron is emitted it will soon meet an
electron and the electron and positron will be annihilated in the
collision producing a burst of energy that pass straight through
the volunteer and can then be detected. By injecting 15O-labeled
water and placing detectors around the volunteer's head a picture
of where the emissions are occurring can be created and that
picture will index where activity in the brain is taking place.

(2) Cerebral responses to pain in patients with atypical facial
pain measured by positron emission tomography', Derbyshire SWG,
Jones AKP, Devani P, Friston KJ, Feinmann C, Harris M, Pearce S,
Watson JD, Frackowiak RSJ, Journal of Neurology Neurosurgery and
Psychiatry 57: 1166-1172, 1994

(3) The physical basis of fMRI is the difference in the magnetic
properties of oxygenated and deoxygenated blood, specifically the
difference in decay time of the MR signal from oxyhemoglobin and
deoxyhemoglobin. This difference in signal characteristics allow
for the localized detection of blood flow in the brain similar to
that from PET imaging but with potentially greater temporal and
spatial sensitivity.

(4) Meditations on First Philosophy, Rene Descartes (1641).
Translated by ES Haldane and GRT Ross in Descartes Key
Philosophical Writings, Wordsworth Classics, 1997, pp. 139-146.

(5) The Knowing Animal: A Philosophical Inquiry into Knowledge and
Truth, Raymond Tallis, Edinburgh University Press (Edinburgh), 2005

(6) `Visual detection is gated by attending for action: Evidence
from hemispatial neglect', Rafal, R. D., Danziger, S., Grossi, G.,
Machado, L. & Ward, R. Proceedings of the National Academy of
Sciences U.S.A. 99, 16371-16375, 2002

(7) The Hand: A Philosophical Inquiry into Human Being, Raymond
Tallis, Edinburgh University Press (Edinburgh), 2003