Your brain, with its billions of neurones, is more powerful than the mightiest supercomputer. So why do you have so much trouble multiplying 573 by 617? And why can't you remember where you left the car keys? According to Australian scientists, the fault lies with our higher-level thinking which blots out a whole range of skills we would otherwise be able to use. New research suggests that there may be a way to release these hidden talents. But there may be a danger.
Some people - known as autistic savants - have no problem with lightning calculations. They can work out what day of the week any given date falls on in an instant. Others draw architecturally accurate pictures from memory after a single glance, or repeat a tune note-perfect.
The character portrayed by Dustin Hoffman in Rain Man was based on a number of real savants. These skills are rare among autistic people, but the question is why they occur at all. Is this a kind of compensation mechanism, or something more complex?
There are competing theories of autism, but it is generally accepted that, while autistic people perceive the details of the world, they do not make connections and grasp it as a whole. They lack "global processing".
If you were shown a scene with some trees and a row of houses, your attention would be grabbed if smoke and flames were billowing out of one window. This is the most memorable feature and if you were to describe the scene, that is what you would concentrate on.
An autistic viewer might be struck equally by every single detail. The smoke and flames might be no more noteworthy than an unusual arrangement of roof tiles. It seems the autistic brain does not have an editor, so every bit of information is presented to the conscious mind. This is why autistic people tend to find new situations overwhelming.
Autism occurs in varying degrees. At the mildest end are people with Asperger's Syndrome. They tend to be punctual, meticulous and often completely absorbed in a hobby such as model trains or computer programming. They have good memories and powers of concentration, but tend to be awkward in social situations whose unwritten rules they find incomprehensible.
Difficulties with communication are a consistent feature of autism, although there is some evidence that autistic people may be able to communicate better with each other than with non-autistics.
At the extreme end of the autistic spectrum are those who never learn to speak. They fail to develop what psychologists call a theory of mind - the understanding that other people have thoughts and feelings. They may not even be able to recognise the shifting patterns of light around them as other human faces. This leaves the profoundly autistic locked in their own world, remote from contact with others.
Early theories of autism considered it to be a mental illness related to schizophrenia. It is now recognised as a neurological condition in which a crucial part of the brain fails to develop.
According to Allan Snyder and John Mitchell of the Centre for the Mind at the University of Canberra, this is what allows savant skills to emerge. They believe that all of us have the ability to see and remember the world in detail, but that the information is filtered out by high-level processes before it is allowed to reach our conscious mind. Autistic types may not get the big picture, but they can tap into brain functions like unconscious calculation and eidetic (photographic) memory.
An alternative theory of autism suggests that the features of autism, such as the appreciation of fine detail, are developed as an alternative to central coherence. According to this view, savant skills are developed in isolated brain areas, and there is no equivalent in the non-autistic brain.
Transcranial magnetic stimulation has given researchers the opportunity to investigate these theories. TMS involves applying a modulated magnetic field to stimulate or suppress activity in a specific area of the brain.
Robyn Young at Flinders University and Michael Ridding of the Royal Adelaide Hospital carried out an experiment to find out how applying a field to the frontal temporal lobe would affect volunteers' ability to carry out a task.
The results, as yet to be published, show that TMS could improve function. Some volunteers were better at calculating days of the week, while others could draw a horse more accurately from memory under the influence of TMS.
The details are yet to be released, and only 17 volunteers were involved, but the effect certainly seems to be real. The test subjects did not show anything as dramatic as the skills of autistic savants, but these are early days. Further experiments with different skills and different parts of the brain will follow, and the technique will be refined. If Snyder and Mitchell are correct, we all have tremendous potential.
The prospects are exciting, but any application will be delayed until we know whether there are any long-term effects. As with autism, there is likely to be a trade-off of mental skills - Young and Ridding found that their subjects had a reduced short-term memory when TMS was applied.
History shows that performance-enhancing drugs often turn out to have side- effects. During the second world war, millions of amphetamines were issued to air crew and other personnel who needed to stay alert for long periods. Only later was it discovered that the drug could produce psychosis.
However, millions of people are already engaged in an experiment of this kind. Mobile phones expose the brain to electromagnetic radiation. The field is much weaker than that used in TMS, but it has a detectable effect on the brain.
Dr Alan Preece of the Bristol Royal Infirmary carried out tests which showed that a simulated mobile phone field could improve reaction time. The mechanism involved is not yet clear.
The effects of a mobile phone call persist after the exposure ends. Swiss researchers found that brain activity was altered for up to three-quarters of an hour after calling. A form of TMS has been used successfully to treat depression, with daily sessions lasting half an hour for two weeks. This can lift depression for up to six months. It seems electromagnetic fields can leave their imprint on the brain for quite some time. If you just want to fire up you magnetic brain-booster to do your annual accounts, you do not want to be locked in savant calculator mode for a week.
There is a great deal still to be discovered. The initial findings should lead to a greater understanding of autism and the workings of the brain in general.
The good news is that we may be able to reshape brain function at will, using magnetic fields to bring out hidden talents. The bad news is that we may already be doing so unwittingly.
