Most People Use Only 10% of Their Brain Power

Whenever those of us who study the brain venture out of the Ivory Tower to give public lectures or media interviews, one of the questions we’re most likely to encounter is, “Is it true that we only use 10% of our brains?” The look of disappointment that usually follows when we respond, “Sorry, I’m afraid not,” strongly suggests that the 10% myth is one of those hopeful truisms that refuses to die simply because it would be so darn nice if it were true (Della Sala, 1999; Della Sala & Beyerstein, 2007). Indeed, this myth is widespread, even among psychology students and other well-educated people. In one study, when asked “About what percentage of their potential brain power do you think most people use?,” a third of psychology majors answered 10% (Higbee & Clay, 1998, p. 471). Fifty-nine percent of a sample of college-educated people in Brazil similarly believe that people use only 10% of their brains (Herculano-Houzel, 2002). Remarkably, that same survey revealed that even 6% of neuroscientists agreed with this claim!

Surely, none of us would turn down a hefty hike in brain power if we could achieve it. Not surprisingly, marketers who thrive on the public’s fond hopes for a self-improvement breakthrough continue to peddle a never-ending stream of dubious schemes and devices premised on the 10% myth. Always on the lookout for a “feel-good” story, the media has played a big role in keeping this optimistic myth alive. A great deal of advertising copy for legitimate products continues to refer to the 10% myth as fact, usually in the hopes of flattering potential customers who see themselves as having risen above their brain’s limitations. For example, in his popular book, How to Be Twice as Smart, Scott Witt (1983) wrote that “If you’re like most people, you’re using only ten percent of your brainpower” (p. 4). In 1999, an airline tried to entice potential flyers by informing them that “It’s been said that we use only 10% of our brain capacity. If, however, you’re flying ........ Airlines, you’re using considerably more” (Chudler, 2006).

If you’re like most people, you’re using only ten percent of your brainpower

source: en.wikipedia.org

Yet an expert panel convened by the U.S. National Research Council concluded that (alas!), in this, as with other miraculous self-improvement claims, there’s no good substitute for hard work when it comes to getting ahead in life (Beyerstein, 1999c; Druckman & Swets, 1988). This unwelcome news has done little to discourage millions who comfort themselves with the belief that the shortcut to their unfulfilled dreams lies in the fact that they just haven’t quite caught up with the secret for tapping their vast, allegedly unused cerebral reservoir (Beyerstein, 1999c). That desired promotion, stellar grade point average, or authorship of the next bestselling novel is within your grasp, say the sellers of cerebral miracle remedies.

Even more questionable are the offerings of New Age entrepreneurs who propose to hone the psychic skills we allegedly all possess with obscure gizmo's for the brain. Self-proclaimed psychic Uri Geller (1996) claimed that “In fact, most of us use only about 10 percent of our brains, if that.” Promoters like Geller imply that psychic powers reside in the 90% of the brain that simple folk forced to subsist on the drudge-like 10% haven’t yet learned to use. 

Why would a brain researcher doubt that 90% of the average brain lies silent? There are several reasons. First of all, our brain has been shaped by natural selection. Brain tissue is expensive to grow and operate; at a mere 2–3% of our body weight, it consumes over 20% of the oxygen we breathe. It’s implausible that evolution would have permitted the squandering of resources on a scale necessary to build and maintain such a massively underutilized organ. Moreover, if having a bigger brain contributes to the flexibility that promotes survival and reproduction—which are natural selection’s “bottom lines”—it’s hard to believe that any slight increase in processing power wouldn’t be snapped up immediately by existing systems in the brain to enhance the bearer’s chances in the continuous struggle to prosper and procreate.

Doubts about the 10% figure are also fueled by evidence from clinical neurology and neuropsychology, two disciplines that aim to understand and alleviate the effects of brain damage. Losing far less than 90% of the brain to accident or disease almost always has catastrophic consequences. Look, for instance, at the much publicized controversy surrounding the non-conscious status and ultimate death of Terri Schiavo, the young Florida woman who lay in a persistent vegetative state for 15 years (Quill, 2005). Oxygen deprivation following a cardiac arrest in 1990 had destroyed about 50% of her cerebrum, the upper part of the brain responsible for conscious awareness. Modern brain science argues that “mind” equals brain function. Therefore, patients like Ms. Schiavo had permanently lost the capacity for thoughts, perceptions, memories, and emotions that are the very essence of being human (Beyerstein, 1987). Although some claimed to see signs of consciousness in Schiavo, most impartial experts found no evidence that any of her higher mental processes had been spared. If 90% of the brain is indeed unnecessary, this

shouldn't have been the case.

Research also reveals that no area of the brain can be destroyed by strokes or head trauma without leaving patients with serious deficits in functioning (Kolb & Whishaw, 2003; Sacks, 1985). Likewise, electrical stimulation of sites in the brain during neurosurgery has failed to uncover any “silent areas,” those in which the person experiences no perception, emotion, or movement after neurosurgeons apply these tiny currents (neurosurgeons can accomplish this feat with conscious patients under local anesthesia because the brain contains no pain receptors).

The last century has witnessed the advent of increasingly sophisticated technologies for snooping on the brain’s traffic (Rosenzweig, Breedlove, & Watson, 2005). With the aid of brain imaging techniques, such as electroencephalograms (EEGs), positron emission tomography (PET) scanners, and functional magnetic resonance imaging (MRI) machines, researchers have succeeded in localizing a vast number of psychological functions to specific brain areas. With nonhuman animals, and occasionally with humans undergoing neurological treatment, researchers can insert recording probes into the brain. Despite this detailed mapping, no quiet areas awaiting new assignments have emerged. In fact, even simple tasks generally require contributions of processing areas spread throughout virtually the whole brain.

Two other firmly established principles of neuroscience create further problems for the 10% myth. Areas of the brain that are unused because of injuries or disease tend to do one of two things. They either wither away, or “degenerate,” as neuroscientists put it, or they’re taken over by nearby areas that are on the lookout for unused territory to colonize for their own purposes. Either way, perfectly good, unused brain tissue is unlikely to remain on the sidelines for long.

All told, evidence suggests that there’s no cerebral spare tire waiting to be mounted with a little help from the self-improvement industry. So, if the 10% myth is so poorly supported, how did it get started? Attempts to track down this myth’s origins haven’t uncovered any smoking guns, but a few tantalizing clues have materialized (Beyerstein, 1999c; Chudler, 2006; Geake, 2008). One stream leads back to pioneering American psychologist William James in the late 19th and early 20th centuries. In one of his writings for the general public, James said he doubted that average persons achieve more than about 10% of their intellectual potential. James always talked in terms of underdeveloped potential, never relating it to a specific amount of the brain engaged. A slew of “positive thinking” gurus who followed weren't as careful, though, and “10% of our capacity” gradually morphed into “10% of our brain” (Beyerstein, 1999c). Undoubtedly, the biggest boost for the self-help entrepreneurs came when journalist Lowell Thomas attributed the 10% brain claim to William James. Thomas did so in the 1936 preface to one of the bestselling self-help books of all time, Dale Carnegie’s How to Win Friends and Influence People. The myth has never lost its steam since.bestselling self-help books of all time, Dale Carnegie’s How to Win Friends and Influence People. The myth has never lost its steam since.

The popularity of the 10% myth probably also stems partly from authors’ misunderstandings of scientific papers by early brain researchers. In calling a huge percentage of the human cerebral hemispheres “silent cortex,” early investigators may have fostered the mistaken impression that what scientists now call “association cortex” had no function. As we now know, association cortex is vitally important for our language, abstract thinking, and performance of intricate sensory-motor tasks. In a similar vein, early researchers’ admirably modest admissions that they didn't know what 90% of the brain did probably contributed to the myth that it does nothing. Another possible source of confusion may have been laypersons’ misunderstanding of the role of glial cells, brain cells that outnumber the brain’s neurons (nerve cells) by a factor of about 10. Although neurons are the scene of the action with respect to thinking and other mental activities, glial cells perform essential support functions for the neurons that do the heavy lifting, psychologically speaking. Finally, those who've searched for the origins of the 10% myth frequently came across the claim that Albert Einstein once explained his own brilliance by reference to the myth. Nevertheless, a careful search by the helpful staff at the Albert Einstein archive on our behalf yielded no record of any such statement on his part. More likely than not, the promoters of the 10% myth simply seized on Einstein’s prestige to further their own endeavors (Beyerstein, 1999c).

The 10% myth has surely motivated many people to strive for greater creativity and productivity in their lives, which certainly isn't a bad thing.

The comfort, encouragement, and hope that it’s generated almost surely help to explain its longevity. But, as Carl Sagan (1995) reminded us (see Introduction, p. 11), if something sounds too good to be true, it probably is.

reference: 

50 great myths of popular psychology : shattering widespread misconceptions about human behavior / Scott O. Lilienfeld … [et al.].