Could you survive using only 10 percent of your brain?
This post is the second in a periodic series exploring common misconceptions around how students learn. We first touched on these misconceptions in our September 2015 report, The Science of Learning, and will be exploring them in more depth over the next few months.
Today’s post from Dr. Melina Uncapher explores the “myth of the 10 percent”: that, at any given time, a human being only uses 10 percent of his or her brain. This enduring myth is perpetuated by pop culture and is believed by about half of educators around the world, according to a recent survey. Uncapher is a neuroscientist, an assistant professor at University of California-San Francisco, a research scientist at Stanford University, and executive director of the nonprofit scienceforgood.org.
You could almost hear the collective cringe around the globe when trailers for the movie Lucy came out a few years ago. The neuroscience community winced in disappointment when our beloved Morgan Freeman spoke the (dreadfully inaccurate) words, “It is estimated that most human beings use only 10 percent of their brain. Imagine if we could access 100 percent!” The film would be a box office smash, but a hard blow for the popular understanding of brain science.
This myth of 10 percent is one of the most pervasive lies we unknowingly perpetuate about the brain, and some recent research has finally provided at least one method we may use to try to debunk this neuromyth.
But first, let’s unpack the myth of 10 percent.
The myth of 10 percent is popular
Lucy is not the only pop culture phenomenon perpetuating this neuromyth; the Limitless movie and now TV show were based on a similar premise that the typical human operates at minimal capacity, but could be bumped up to superpower status by tapping into that other 90 percent. Unfortunately, this myth is not only widespread in pop culture, but also in the education world. Approximately half the surveyed educators around the world believe this myth.
Where did the myth come from?
Like any respectable urban legend, the origins of this myth are debated. Some attribute it to Einstein, who once told an interviewer that he only used 10 percent of his brain (although his dry sense of humor is even more well documented, so one can deduce with some confidence that he made such a statement in jest).
Others say the myth stemmed from the experiments of Pierre Flourens in the 1800s, who removed more and more bits of brain from animals to see how their behavior was affected, and concluded that just a small part of the ‘cerebral lobes’ were needed for mental faculties. In analogous experiments a century later, Karl Lashley stimulated the brain with low frequency electric shocks and found very few brain regions responded discernably to these shocks. Still other early studies using chemical stains showed only ~10 percent of brain cells were neurons, which were thought to be the only active parts of the brain. Not so, it turns out.
The advent of sophisticated brain imaging technologies in the past two decades has revealed a very different story. The lump of wetware between our ears that is ~2 percent of our body weight consumes ~20 percent of the body’s energy. All that energy is not just for 10 percent of your brain. It turns out that 100 percent of your brain is active 100 percent of the time. Quite like the heart, it is always on. And rightly so, as it is not only allowing you to read this sentence while also worrying about all those unanswered emails and think about what you’ll have for dinner tonight, but it is also monitoring your heart rate, blood pressure, breathing quality, balance, temperature, and thousands of other processes that are operating under the hood, outside your conscious awareness (for an engaging peek into the wonders of the human mind, have a look at our 6-part PBS tv series, hosted by Dr. David Eagleman).
Why do we believe the myth so much?
While the following ideas are untested hypotheses, they’re useful frames to spark discussions about why this myth has captured popular and educational cultures for two centuries.
One of the first popularizers of this myth is thought to be Dale Carnegie in his widely read self-help book How to Win Friends and Influence People, wherein he attributes one of the fathers of psychology, William James, as saying “the average person only develops 10 percent of his latent mental ability.” The inherent optimistic belief in human potential may be one of the reasons people self-select to be educators in the first place (but note this is only my untested hypothesis!). This idea that there exists so much untapped potential in our students that we, the educators, could mobilize is certainly what intrigued me about the myth of 10 percent before I knew the data. Perhaps it was what intrigued you as well.
The other reason for the myth’s enduring popularity is, I suspect, the fault of us neuroscientists and our science journalist friends. When we show pictures of, and discuss, brain regions as ”lighting up,” the “blobs” shown seem to cover only a fraction of the brain, thus again perpetuating the myth that only small bits of the brain allow us to do or think all manner of things (note we call it “blob-ology” and “neo-phrenology” in jest and with much self-sarcasm). However these blobs are typically showing which brain regions are more active during condition A than condition B, not which regions “light up” during condition A. It’s not that the regions are sleeping until called into action, but rather they’re always working and ramp up their activity when in higher demand. But that can often get lost in the business of the headline.
Why is this myth harmful for classroom practice?
On its own, this myth may spur educators and students to believe that students can tap into their latent potential, which is not a bad thing. In fact, we know that academic mindset interventions (such as Carol Dweck and colleagues’ growth mindset interventions) are most effective and long-lasting when framed around this very idea: that the student has the power to improve. However, the ability to improve is framed around the messaging that the brain is like a muscle and can improve with effort, NOT that the brain is a lazy organ and can improve when awakening the sleeping 90 percent.
Where the myth of 90 percent (and many other myths) may be harmful is when funding gets appropriated (and time and energy directed) to programs that promise to unlock the hidden potential of the 90 percent. Because the brain is already active 100 percent of the time, these programs are a waste of time and should not be replacing good teaching and learning practices. It is quite simply irresponsible of us researchers to allow this myth to continue to eat up finite resources.
A call to action: let’s debunk this myth once and for all!
Pop quiz: having read to the end of this post, what is your position on the myth of 10 percent? Or coming at the question another way: How would you explain your position on the myth to your students right now?
Research tells us that the way we try to correct misinformation is critical to whether we may be successful in those efforts. Apparently the well-tread formula of highlighting the myth, debunking the myth with data, and concluding with the statement that the myth is false, is quite effective at…perpetuating the myth! As concluded by Norbert Schwartz and colleagues in studies investigating the ”backfire effect” in myth-busting, attempts to warn people about the false beliefs they hold, if done in a certain way, can reinforce those false beliefs.
In a new study designed to test a way to reduce this backfire effect, Christina Peter and Thomas Koch showed that asking someone to form an immediate judgment about the issue in the moment they’re exposed to it increases the likelihood she’ll remember the correct information, rather than the myth. So if you actually had a think (or do so now) about where you stand on this topic, it is more likely you’ll be one of the leading few who remembers that we use 100 percent of our brain 100 percent of the time, rather than misremembering the 10 percent myth.
Please help your school and district move away from programs that promise to unlock that lazy 90 percent, and replace them with time-tested, evidence-based practices grounded in the science of learning. For a great primer on some of the most effective techniques, see Deans for Impact’s Science of Learning white paper here, and video of the national launch here.