The 10% Myth

This is perhaps the most persistent and widespread belief about the brain. Like a Dawkinian meme it has infiltrated deep into the collective psyche, permeating society and influencing popular cultural. Entire novels, plays and movies are built on this motif and, being so pervasive, some movies don’t even need to explain the idea. For instance in the movie “Defending your Life” Albert Miller dies in a car accident and upon reaching the afterlife finds he has to justify his fear-based life or be “sent back”.  It is explained to Miller that, due to fear, humans use so little of their brain potential with his defence attorney asserting, "When you use more than 5% of your brain, you don't want to be on Earth, believe me." Similarly, in the movie “Wedding Crashers” an oblique reference is made to the 10% belief when one of the characters asserts that men only use 10% of their hearts. But the latest (and in my opinion the best) movie portrayal of this belief is to be found in the 2011 film “Limitless” in which Eddie, a struggling writer, is persuaded by his ex- wife’s brother, Vernon, to try a new drug, NZT-48, that will allow him to access 100% of his brain:

Eddie: “What’s in it?”

Vernon:  “They’ve identified these receptors in the brain that activate specific circuits. And you know how they say we can only access 20% of our brain…Well what this does…it let’s you access ALL of it.”

This belief is commonly used as a motivator for unleashing untapped potential; for instance, it has been claimed that Einstein used 15% of his brain and that if only we could employ an equal percentage of our brain capacity we too could be “Einsteins”.  It is also used by some (Uri Geller) as an explanation for paranormal phenomena; the idea being that during our prehistoric past, as we hunted and foraged amidst the vast and hostile environment of the African savannah, ESP abilities served a survival utility; but that due to the “civilising” effect of modern society, with the associated reliance on technology, these once adaptive ESP abilities have atrophied among the general populace.

But just where did this idea come from? And more importantly, is it true? If we look back through the history of neuroscience and psychology one place where we find a hint of this idea is in the writings of William James (1842-1910). In popular public lectures William James often claimed that we only reach a small fraction of our brain’s full potential.  More specifically, James came up with the idea of reserve energy which supposes that within the individual there are both physical and mental reserves of energy which can be tapped into and utilised. This idea is presented in his 1907 article “The Energies of Men”.  American psychologist and James’s protégé, Boris Sidis, used this idea as the basis of an educational experiment with his son William Sidis.  Boris commented on his application of reserve energy in the raising of his son in a circa 1910 issue of New York American:

“I do not believe in the prevailing system of education for children. I have raised my son upon a system of my own, based to some extent upon the principles laid down by professor William James.”

Judging form the results of this experiment (it is claimed William Sidi had an IQ of 250 – 300!) there would appear to be some truth to James’ reserve energy theory. Such results highlight that the critical period of neuro-genesis, synapto-genesis and pruning that takes place during early childhood is very much shaped by expectations and experience. If the case of William Sidi is to be taken at face value it strongly suggests that he was utilising the potential of the human brain in a manner not typical of conventional childhood development. 

But, the origins of the 10% idea originate with James only indirectly. It is through the writings of self-help guru Dale Carnegie (1888 – 1955), and specifically his “How to Win Friends and Influence People” that this idea gained traction.  The idea that we only use 10% of our brain was first mentioned by Robert Lovell in the introduction to the 1936 edition of the book quoting William James as saying:

“Compared to what we ought to be we are only half awake. We are making use of only a small part of our physical and mental resources. Stating the thing broadly, the human individual thus lives far within his limits. He possesses powers of various sorts which he habitually fails to use.”

Of course, James’s argument that we are not making full use of our potential is inarguable;  just as we don’t make full use of the potential of our bodies physical capacities we similarly don’t make full use of the brains full potential. But the 10% myth isn’t usually framed in such terms; rather, it asserts that the fully developed adult brain is underutilised in so far as only a small percentage of the brain’s function is being utilised.  This conjures up the image of only a small region of the brain being active while the remaining 90% lays dormant. The myth couched in these terms is easy to dismiss.  Lesion evidence (seeing what goes wrong when certain parts of the brain are damaged) and modern imaging techniques (fMRI, PET) thoroughly demonstrate that every part of the brain is necessary for normal function. However, if the question is framed in terms of how much of that normal brain function is under conscious control, a less clear cut and more interesting avenue of thought opens up.

In his book “Brain Wars” neuroscientist Mario Beauregard relates the well documented case of a man named John who suffered from a debilitating disease known as ichthyosiform erythrodermia or “fish skin” in which his whole body was covered in a thick black substance bearing no resemblance to healthy, normal skin. After trying numerous unsuccessful skin grafts, and out of sheer desperation, it was suggested by anaesthiologist Albert Mason, who’d had some reasonable success with warts, to try hypnotherapy. Mason treated John’s right arm, moving onto the trunk and the legs, giving him basic hypnotic suggestions such as “Your right arm will clear”.  This initial hypnotherapy resulted in 50% of his legs and 95% of his right arm clearing; within a year of completing treatment John had become a “normal, happy young man”.

Such cases as John’s above, as well as such inexplicable phenomena as the placebo effect, strongly suggest that, at the very least, there are potentials for self-healing that ordinarily we are unaware of. These potentials for healing are usually not amenable to conscious manipulation but somehow, in a way not fully understood, certain mind states increase one’s ability to utilise potentials for healing not typically under our control. Hypnosis is just one way of accessing this generally unconscious potential. Similarly, there are documented accounts of advanced yoga practitioners controlling physiological responses not usually open to to conscious control.

So, while the 10% myth, as popularly thought of, is easily debunked in light of the overwhelming evidence to the contrary, I think it would be arrogant to suppose that out knowledge of the brain and its potential is complete. Neuroscience is a relatively young science and I believe many surprises still await us.