We’re No Slaves to Our Senses

By Stuart Derbyshire
Spiked, August 24, 2007

Edited by Andy Ross

Making up the Mind: How the Brain Creates our Mental World
by Chris Frith
Blackwell, 2007, 232 pages

Positron emission tomography (PET) involves the injection of a radioactive isotope that rapidly decays in the bloodstream of the volunteer. 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. Using this technique, a picture of what the brain is doing when somebody thinks, acts or feels can be built.

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. The same problem faces those of us who hope to understand brain function.

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.

Professor Chris Frith 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.

Frith describes schizophrenia as the consequence of some damage to brain function. He makes the 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 wrong in people with schizophrenia.

Frith 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.

Frith explains that 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. 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 our senses.

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."

He expresses ambivalence regarding free will: "I am firmly convinced that I am a product of my brain, as is the awareness that accompanies me. ... 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 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 is a problem because the world does not divide itself into fact-sized chunks. It is through our relationship with the world that we can come to divide it. The facts that we can lay claim to about the world are selected from an almost infinite number of potential facts, but we can have great confidence that the facts we are gathering are real.

Frith 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 enable a specific viewpoint to flourish and an independent existence to announce itself.

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.

The negotiation of constraint and indeterminacy cannot be located in parts of the brain and recorded on a graph. That negotiation is an active, lived process and free will is possible because of the ability to interrogate nature. Early human mentality would have resided in the relationship of the organism to stimuli in the environment that are set free by exploration to address specific biological needs. Within that relationship, freedom and agency begin.

The fundamental mistake that Frith makes 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 a sense that agency is illusory.

Chris Frith is Professor in Neuropsychology at the Wellcome Trust Centre for Neuroimaging at University College London.

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.

The Ross verdict: Whatever the truth about agency and free will as it emerges in the next few decades, I am convinced that what we are now learning about the brain will be of decisive importance for getting the story right. Attempts to work around the role of the brain with stories about exploration and the environment have some interest, but they do not yet offer the prospect of substantially advancing our scientific understanding of the mind.

Magnetic Personalities

The Economist, August 30, 2007

Magnetoencephalography (MEG) detects magnetic signals produced by the electrical activity of brain cells.*

Apostolos Georgopoulos and his colleagues at the University of Minnesota, Minneapolis, think MEG could be adapted for medical use. In a recent paper in the Journal of Neural Engineering, they report that the general hum of brain activity might contain diagnostic information.

Dr Georgopoulos found a characteristic pattern in the magnetic fluctuations of healthy people's brains. He asked ten volunteers to stare at a point of light as they lay under his machine. Each run of the experiment used 248 sensors and every sensor took 45,000 readings over the course of a run.

He wondered whether the brains of people with neurological diseases might have different magnetic patterns. He invited patients with a clear diagnosis of one of six afflictions—Alzheimer's and schizophrenia among them—to lie in his machine. Then he recorded the magnetic fluctuations of their brains.

He analysed the results using discriminant function analysis. This allows complicated data to be reduced to a small number of components whose co-ordinates can be plotted on a graph. Each of the diseases produced a distinct cluster. Healthy brains produced a cluster that did not overlap with any of the diseases.

* MEG signals are in the femtotesla range, about a billionth of the strength of the Earth's magnetic field.

A MEG scanner