The 10 per cent myth

How often do you hear it said that we use only 10 per cent of our brains? No one seems to know where this extraordinary claim came from, although it has certainly been around a while. A 1929 advertisement for the Pelman Institute, once famous for its courses on self-improvement, proclaimed that ‘Scientists and psychologists tell us we use only about TEN PER CENT of our brain power’, but does not divulge the identity of the source. Perhaps they had in mind the pioneering nineteenth-century psychologist William James (brother of the novelist Henry James), who did once declare that we use only a small part of our physical and mental resources, but he seems not to have mentioned a specific percentage.

The suggestion of scientific backing, however spurious, continues to give the 10 per cent myth some leverage in the self-improvement industry. In Steve Biddulph’s book The Secret Life of Men, the target is men, who are urged to dig further than 10 per cent into their minds and discover the potential for deeper personal relationships. But women are also targeted. Caroline Myss, author of several best-selling books including Entering the Castle, appeals to women to go beyond the 10 per cent limitation to find greater powers of intuition and self-fulfilment.

The 10 per cent myth also provides a convenient explanation for extraordinary powers. Albert Einstein is said to have endorsed it, and Uri Geller, famous for his claim to be able to bend spoons through the power of thought, once divulged that he gained his psychic powers by discovering how to break the 10 per cent barrier. Geller’s demonstrations are easily duplicated without resort to psychic powers by stage magicians, including James Randi, who wrote a book entitled The Magic of Uri Geller—later renamed The Truth about Uri Geller. Geller’s exploits were also unmasked in New Zealand by two psychologists, David Marks and Richard Kammann, who were able to repeat Geller’s demonstrations on television, again without any claim to psychic powers. They too wrote a book exposing the field of psychic phenomena, and Geller in particular, entitled The Psychology of the Psychic. These books are highly recommended, but alas do not have the selling power of books that proclaim the existence of the psychic.

One may even wonder whether we need any brain at all. In 1980, Science published an article entitled ‘Is your brain really necessary?’ This was followed in 1982 by a Yorkshire Television programme with the same title. The provocative question was based on the work of a British paediatrician, John Lorber, who described cases of individuals with hydrocephalus and seemingly massive reductions in brain matter, who nevertheless seemed to function normally. The most striking case was a young man with a measured IQ of 126 and a degree in mathematics, yet brain scans suggested that he hardly possessed any brain at all.

The Science article was presented as a news item rather than a scientific report, and the cases described by Lorber were never published as peer-reviewed articles. We don’t know whether the young mathematician had normal social skills, or even whether he could tie his shoelaces. In any case, reduced brain volume need not imply a reduction in the actual number of brain cells, which may simply have become packed more tightly. Moreover, the pressure of fluid in hydrocephalus causes brain matter to be pressed against the inside of an enlarged brain case, which can give the illusion of reduced brain matter, just as an inflated balloon may seem to have less physical substance than a deflated one.

The idea that the brain may be unnecessary is especially attractive to those who would like to believe that there is more to the mind than mere matter. Such a belief is comforting, because it suggests that the mind might survive the death of the brain, allowing eternal contemplation of life’s mysteries. The vast bulk of evidence, though, speaks to the contrary. Brain damage, no matter how small, nearly always seems to have an effect on mental function, the more so as assessment becomes more sophisticated.

One part of the brain that has posed something of a mystery, though, is the area to the front of the brain known as the prefrontal cortex. One of the most famous cases in neurology is that of Phineas Gage, a railroad construction foreman, who in 1848 was victim of an explosion that saw a metre-long tamping rod blown through the anterior part of his prefrontal cortex, causing major damage. His intellectual function seemed remarkably unimpaired. What did change, though, was his personality. Once responsible and trustworthy, he became irreverent and profane. People with damage to the prefrontal cortex often show very little impairment on routine tests of mental function, but may become disoriented in their everyday lives. The best we can say, perhaps, is that the prefrontal cortex is rather diffuse in its functions. In some ways it may contribute to rather indefinable aspects of our lives, including such elusive concepts as free will.

Modern brain-imaging techniques have allowed us to observe which parts of the brain are active when people are asked to perform mental tasks, from simple word naming to making aesthetic judgements. This work has failed to reveal any part of the brain that is conspicuously silent, as though waiting to be put to use. No doubt we could all have done more with our lives, but we are born to be specialists, with limitations imposed by culture rather than by unused brain space. Each child has the capacity, for instance, to learn any of the world’s 6000 or so languages, but no one child could possibly learn more than a tiny fraction of these—even if she uses 100 per cent of her brain. The mental exploits of the human population far exceed those of any individual brain, but most of us probably make a fair stab at using the potential we have. Well, more than 10 per cent, anyway.