I've heard claims that the average person uses only 10% of their "brain power," whatever that means. The implication, though, is that there the majority of our brain's potential is untapped. However, I've often heard this refrain from people who are selling "training" or "secrets" to unlock the unused potential of our brain.
It seems unlikely that there would be evolutionary advantages to having a brain whose capabilities lie largely untapped.
I'm curious - what percentage of our brain do we use, or can it even be quantified in such measures?
Neurologist Barry Gordon describes the myth as laughably false, adding, "we use virtually every part of the brain, and that [most of] the brain is active almost all the time". Neuroscientist Barry Beyerstein sets out seven kinds of evidence refuting the ten percent myth:
Studies of brain damage: If 90% of the brain is normally unused, then damage to these areas should not impair performance. Instead, there is almost no area of the brain that can be damaged without loss of abilities. Even slight damage to small areas of the brain can have profound effects.
Evolution: The brain is enormously costly to the rest of the body, in terms of oxygen and nutrient consumption. It can require up to twenty percent of the body's energy — more than any other organ — despite making up only 2% of the human body by weight. If 90% of it were unnecessary, there would be a large survival advantage to humans with smaller, more efficient brains. If this were true, the process of natural selection would have eliminated the inefficient brains. By the same token, it is also highly unlikely that a brain with so much redundant matter would have evolved in the first place.
Brain imaging: Technologies such as Positron Emission Tomography (PET) and functional magnetic resonance imaging (fMRI) allow the activity of the living brain to be monitored. They reveal that even during sleep, all parts of the brain show some level of "activity. Only in the case of serious damage does a brain have "silent" areas.
Localization of function: Rather than acting as a single mass, the brain has distinct regions for different kinds of information processing. Decades of research has gone into mapping functions onto areas of the brain, and no function-less areas have been found.
Microstructural analysis: In the single-unit recording technique, researchers insert a tiny electrode into the brain to monitor the activity of a single cell. If 90% of cells were unused, then this technique would have revealed that.
Metabolic studies: Another scientific technique involves studying the take-up of radioactively labelled 2-deoxyglucose molecules by the brain. If 90 percent of the brain were inactive, then those inactive cells would show up as blank areas in a radiograph of the brain. Again, there is no such result.
Neural disease: Brain cells that are not used have a tendency to degenerate. Hence if 90% of the brain were inactive, autopsy of adult brains would reveal large-scale degeneration.
The myth that we use only 10% of our brain is finally being proved untrue, because over the last few decades, we have invented new technologies (such as Positron Emission Tomography and Functional Magnetic Resonance Imaging) that can show the metabolism of the brain. In any one single activity (talking, reading, walking, laughing, eating, looking, hearing, etc) we use only a few per cent of our brain - but over a 24-hour day, all the brain will light up on the scan.
Obviously not all the brain is in use at once. At any given time about 5 percent of the neurons are active, the only sense in which the old saw is even close to true. (Good thing, too, or you'd have the equivalent of a grand mal seizure, a mental electrical storm in which all the neurons fire continually.) The parts of the brain are highly specialized, and some areas are more active than others depending on the task at hand. But all the parts do something, and it seems safe to say that over time you use pretty much all your brain, just as most people use all their muscles to some degree.
The 10% statistic is a myth. Mythbusters tested, and it is closer to 30% at a given instant, although all parts of the brain are used over a longer time period.
While hooked up to a magnetoencephalogram (MEG), a neuroimaging device that measures magnetic fields produced by the brain's electrical currents, Tory exercised four different neurological regions with memory drills, math calculations, word associations and image comparisons. Over the course of the MEG exam, around 35 percent of Tory's brain jumped into action, busting the brain myth.
Cognitive enhancing drugs similar to "NZT-48" are quite real though, an example being a drug called PRL-8-53.