Luc Besson’s latest sci-fi romp, Lucy, is based on the premise that the average person only uses 10% of their brain. This brain-myth has been fodder for books and movies for decades and is a tantalizing plot-device. Alarmingly, however, it seems to be widely accepted as fact. Of those asked, 48% of teachers in the UK, 65% of Americans and 30% of American Psychology students endorsed the myth.
In the movie, Lucy absorbs vast quantities of a nootropic that triggers rampant production of new connections between her neurons. As her brain becomes more and more densely connected, Lucy experiences omniscience, omnipotence and omnipresence. Telepathy, telekinesis and time-travel all become possible.
It’s true that increased connectivity between neurons is associated with greater expertise. Musicians who train for years have greater connectivity and activation of those regions of the brain that control their finger movements and those that bind sensory and motor information. This is the first principle of neural connectivity: cells that fire together wire together.
But resources are limited and the brain is incredibly hungry. It takes a huge amount of energy just to keep it electrically ticking over. There is an excellent TEDEd animation here that explains this nicely. The human adult brain makes up only 2% of the body’s mass yet uses 20% of energy intake. Babies’ brains use 60%! Evolution would necessarily cull any redundant parts of such an expensive organ.
From studying the development of the brain in babies, scientists know that pruning back connections can be just as important as forming them. Shortly after a baby is born there is an exuberant proliferation of connectivity between the neurons followed by rampant pruning of pathways that are underused. During peak pruning periods, it has been estimated that as many as 100,000 connections may be eliminated per second. This is the second principle of neural connectivity: use it or lose it!
As an example, all babies are able to discriminate any language phoneme (the basic sounds that make up a language) until 6 months of age. After this they become increasingly tuned in to just those phonemes used by their local language. This enables babies to more swiftly learn their native tongue. Japanese does not distinguish between |l| and |r| so adult English-learners struggle to even hear the difference between these two phonemes.
Any unused parts of the brain quickly die off to free up resources needed to strengthen those connections that are most often used. This tunes the brain to be exquisitely well adapted to specifically the environment it finds itself in. In this light, the idea that 90% of the brain is lying dormant, waiting for some product, program or drug to access it, seems ludicrous.
The 10% myth is appealing because it’s exciting to think that we have so much untapped potential. It’s lucrative because any product or philosophy that claims to access that potential is going to be very attractive. As smart drugs become increasingly available, the idea that there is a short-cut to extraordinary cognitive abilities is likely to become even more widespread.
There are numerous science blogs and articles explaining why the 10% myth is false but are these arguments filtering down to children? Prof Bruce Hood and I surveyed 300 9-14 year olds in the UK and found that three-quarters believed the myth!
Happily, science lectures do seem to make a difference. Prof Hood delivered a series of demonstrations explaining the ‘Cells that fire together wire together’ and ‘Use it or lose it’ principles of brain connectivity. (These and other demonstrations have been adapted as teaching materials here.) Even 6 weeks after the lecture, 90% of the children surveyed still knew that the 10% myth was false.
Numerous critics have attacked Besson’s use of the 10% myth as the premise of Lucy. When asked how he felt about this he replied, “It’s totally not true. Do they think that I don’t know it’s not true? I work on this thing for nine years and they think that I don’t know it’s not true? Of course I know it’s not true!”
It is unfair to criticise science-fiction for not sticking to the facts. I want my science-fiction to be entertaining and thought provoking, not true. What’s more confusing is when marketers and self-help gurus repeatedly present the 10% myth as fact. These are the real villains in the story.