Fact Friday: We Use 100% of Our Brains

There are a lot of myths about psychology, but none of them are as popular as the idea that people only use 10% of their brains. Although it's nice to think that humans have the capacity to be 90% better, the truth is that we use 100% of our functional brain capacity, although not always at the same time.

In 1908, William James, considered to be the father of American psychology, wrote in his book The Energies of Men, that "we are making use of only a small part of our possible mental and physical resources". This was later misquoted by Lowell Thomas in the 1936 foreword to How to Win Friends and Influence People where he claimed James said people only used 10% of their full potential. Self-help gurus, motivational speakers and life-coaches quickly began using this false statistic to encourage people to tap into the 'unused' 90% of their brain, often with the aid of whatever book or product they were marketing. The popular media also got hold of this misinformation and quickly started quoting it in movies, television shows and advertisements.

Would you really hire someone who only used 10% of their brain??

The human brain weighs 3lbs, which is about 2% of the average person's body weight. It is one of the largest organs in the human body and uses an astonishing 25% of the body's energy to function. That's quite a lot of power in terms of the body's resources. The brain also gets 15% of the heart's blood supply and 20% of the body's oxygen intake. The body, nature's most efficient machine, would hardly waste such a large quantity of resources on an organ which only utilises 10% of its capability.

Brain activity is shown using false-colour in these PET scan images.
Red and yellow areas show high levels of activity, green shows average levels and light and dark blue show low levels.
Here you can see that different parts of the brain are active while performing different tasks.

Positron Emission Tomography (PET) scans have also revealed that the human brain is always active. Even when we sleep, parts of the brain, like the areas that control breathing and heart rate are still hard at work and helping to keep us alive. Of course, all the brain's areas are not active at the same time. Different parts of the brain are responsible for different things and they become active when we need to use them. As you can see from the image above, activity levels change in the brain regions when we engage in looking, listening, thinking and other daily tasks. 

Here is a quick breakdown of the brain's regions and their roles:

Colour-coded, for the pleasure of your occipital lobe ;)

Frontal lobe: decision making; problem solving; purposeful behaviours; consciousness; emotions.
Parietal lobe: processes sensory information from the body; creates thoughts.
Temporal lobe: memory; emotions; hearing; language; learning.
Occipital lobe: vision
Cerebellum: movement; balance; posture; strength; spatial motion.
Brain stem: connects the brain to the spinal cord; controls heart rate, breathing, eating, sleeping.

There are also many other parts within these areas of the brain that are responsible for things like producing and regulating hormones and chemicals in the brain, and receiving and interpreting the body's natural electrical charges.

In the case of brain damage, some parts of the brain may not function as well as they used to, or they may even stop working entirely. You may notice that people who have had a stroke might experience difficulty in speech, vision, balance or another area that they never had problems in before. This is because the stroke has caused damage in a particular region of the brain that is responsible for the diminished activity. If we only used 10% of our brains, damage from strokes, accidents or diseases would have minimal effect on our functioning. However, because every area of the brain is needed for an important function, the slightest injury to the brain can have serious negative effects.

The brain is fascinating organ, though. It can actually detect what areas of the brain are inactive, and once the damage is not too severe, can re-purpose parts of the brain for use, which is termed neural plasticity. If the brain damage is so severe that an area of the brain can no longer function, then here is where we can say that we use 100% of our functional brain, instead.

The brain can also eliminate unused connections. Children, for example, have many more connections in the brain than adults. This helps them to learn information, such as a second language, or intricate sports manoeuvres. However, if the child doesn't learn these additional skills, there is no use for the extra connections, and the brain gets rid of them in a process called synaptic pruning. Not only does the brain eliminate these unneeded connections, it also strengthens the ones that the child uses regularly.

Is your child an aspiring Vivaldi?
His or her brain has pruned away the unused connections and focused in
on strengthening the connections used in skills that are regularly practised.
Photo from www.allthingsstrings.com

Although it might not seem like it sometimes, human beings use all of their brain's capacity. So, the next time you hear someone say that people only use 10% of their brains, you can tell them that 100% of your brain knows that they're wrong ;)