A large body of research has shown humans tend to be cognitive misers (Stanovich et al. 2016). We can’t afford to engage in hard thinking all the time because it isn’t efficient. In our daily lives, we need to think at different levels in different situations. Too much thinking when engaging in trivial situations may drain cognitive resources needed for more complex decision making efforts. From an evolutionary perspective, cognitive shortcuts help us satisfy needs without over extending our brain resources.
A primary characteristic of well-learned information is the ease at which it is retrieved. As an example, when first learning statistics it is tiring and often a huge headache. As learning progresses, it becomes easier to perform statistical procedures; the brain areas involved—and their patterns of communication—have changed. Producing the right outcome becomes more efficient. These changes lead to the use of less brain resources being dedicated to the task. A consequence of strong learning occurs across learning situations and is represented by strong learning/memory connections (connections between brain cells). However, being a cognitive miser under some circumstances may lead to poor decision making (Stanovich et al. 2016). Research involving rational thinking/critical thinking provides evidence that it is often this lack of thinking—or cognitive miserliness—that leads to irrationality. In the cognitive science literature, this is referred to as a processing problem.
A common claim is we only use 10 percent of our brains. Does our tendency to be cognitive misers support this claim, or is this claim an oversimplification of the complexities involved with brain functions and thinking? When discussing neuroscience with my students the question always comes up: Do we really only use 10 percent of our brains? The answer is no. This myth is often perpetuated by the media and is common in everyday discussions. Some people state this claim as if supported by scientific evidence, even though evidence indicates that large portions of the brain are active, to some degree, most of the time.
This belief has been around for decades. Aaron Carroll and Rachel Vreeman report that for over 100 years, some have believed humans only use 10 percent of their brains (Carroll and Vreeman 2009). The use of the myth in advertising dates back as far as 1944, when the Pelman Institute, promoters of self improvement courses, claimed the only thing holding you back from reaching your potential is a scientific fact: “you are only using one-tenth of your real brain power!”(Wanjek 2003). Lowell Thomas, in writing the preface to D. Carnegie’s 1936 self help book How to Win Friends and Influence People, claimed that William James would often say an average person only develops 10 percent of their mental ability (Jarrett 2015). A possible source for the origin of the myth may be attributed to Albert Einstein. Supposedly, he told a reporter he used the full capacity of his brain, rather than the 10 percent most people use. Researchers have failed to find any such quote from Einstein. On the website Neuroscience for Kids, information is provided that shows that the myth has even been promoted by an airline: “It’s been said we use a mere 10% of our brain capacity. If however, you’re flying *** from *** Airlines, you’re using considerably more” (Neuroscience for Kids 2020).
Hollywood has also played a role in disseminating the myth. In the movie Limitless, the film’s star takes a wonder drug that allows him to use all his brain—presumably much more than the small percentage used by other humans. The movie poster for the movie Lucy starring Scarlett Johansson, says “[t]he average person uses 10% of their brain capacity … imagine what she could do with 100.”
Perception, cognition, emotion, motivation, voluntary movement, and vital functions (functions necessary to maintain life) involve the brain and specific patterns of connectivity among brain areas. Different areas and patterns of connectivity are associated with different tasks and computations. Sensory information from the sensory organs are constantly sent to the brain; even while sleeping, widespread brain areas are active. Areas in the brainstem are involved with vital functions such as heart rate, blood pressure, and breathing. The brain is the body’s CEO.
How much of our brain do we use? A wide range of brain scans show that our entire brain is active, to some degree, most of the time. When observing micro level localization (involving individual brain cells or very few cells), inactive areas are not found. Surgeons that probe the brain find functions for almost every area; they don’t find non-functioning areas. Damage to small portions of the brain often result in serious negative outcomes. Brain scientist Barry Beyerstein pointed out damage to almost any brain area has specific effects on human capabilities. If we only use 10 percent of our brain, we shouldn’t experience such drastic effects from damage, to what is often relatively small amounts of brain area (Carroll and Vreeman 2009). There is a brain network-default mode network that becomes more active when trying to not think. This network has been identified in studies comparing brain activity during a cognitively challenging activity to brain activity during rest (Greicius 2003). During the cognitively challenging activity, the default network shows decreased activity, while during resting state activity increases.
Even though the adult human brain accounts for approximately 2 percent of total bodyweight, it uses around 516 calories per day (Herculano-Houzel 2016). That is a large number of calories for an organ that makes up a small percentage of total bodyweight. From an evolutionary perspective it doesn’t make sense that an organ requiring so much energy would contain so much non-functional mass.
Humans often use cognitive shortcuts, but that isn’t evidence that we only use 10 percent of our brains. Our brains are constantly bombarded with sensory information and widely distributed brain areas are involved in communication and processing information virtually all the time.
Carroll, A.E., and Vreeman, C. 2009. Don’t Swallow Your Gum: Myths, Half-Truths, and Outright Lies About Your Body and Health. New York, NY: St. Martin’s Griffin.
Greicius, M.D., et al. 2003. Functional connectivity in the resting brain: A network analysis of the default mode hypothesis. Proceeding of National Academy of Science 100(1), 253–258.
Herculano-Houzel, S. 2016. The Human Advantage: A New Understanding of How Our Brain Became Remarkable. Cambridge, MA: The MIT Press.
Jarrett, C. 2015. Great Myths of the Brain. Malden, MA: Wiley Blackwell.
Neuroscience for Kids. 2020. Do We Only Use 10% of Our Brains? Retrieved on February 23, 2020 from https://faculty.washington.edu/chudler/tenper.html.
Stanovich, K., et al. 2016. The Rationality Quotient: Toward A Test of Rational Thinking. Cambridge, MA: The MIT Press.
Wanjek, C. 2003. Bad Medicine: Misconceptions and Misuses Revealed, From Distance Healing to Vitamin O. Hoboken, NJ: Wiley.