Why do scientist say we only use 10% of our brain? How do they know?

Answer 1

Actually, not many psychologists and scientists support that fact. It is said to be a myth. Here are some links below that lead to essays written by experienced scientists:

Myths About the Brain: 10 percent and Counting
Eric Chudler, Ph.D.
http://www.brainconnection.com/topics/?main=fa/brain-myth
Excerpt: "Do we really use only a small portion of our brain? If the answer to this question is yes, then knowing how to access the "unused" part of our brain should unleash untapped mental powers and allow us perform at top efficiency. Let's examine the issue and attempt to get at the truth behind the myth."


The Myth of the 10% Brain
David A. Morton, M.D.
http://www.rense.com/general16/myth10.htm
Excerpt: "Ask yourself this: how could someone know that we only use about 10% of our brain capacity? How could you know a glass is 10% full, unless you know the total volume the glass holds? To arrive at a rational answer, we would have to know what capacities constitute 100% of brain function. Unless we want to engage in wild speculation, we would have to find a number of super-people (assuming they exist) and then measure their abilities against the capacities of a number of common folk. Then we could have some meaningful data. Of course, we wouldn't know what to measure­a super-person would have to tell us about their super-capacities and how to rate them. In fact, we might not know a super-person unless they came forward and confessed to being superior. If a super-person uses their brain 10 times better than the rest of us, we could guess that intellectually a super-person would have an IQ of at least 1000. Suppose there was someone who was only really half of a super-person? With their 500 IQ they could probably fool us into thinking they were a fully-developed super-person. We can't measure an IQ of 500 any better than we could measure one of 1000. Such a deceit by a half super-person would ruin the whole experiment. Some people already assure us that they are a super-person who has spiritually reached the highest levels of consciousness, and are ready to bestow that knowledge on the rest of us. There are plenty of people charging for such services, and some of these individuals will become rich and authoritative within their following. But such self-inflation is hardly rational evidence. "


The Ten-Percent Myth
Committee for the Scientific Investigation of Claims of the Paranormal
http://www.csicop.org/si/9903/ten-percent-myth.html
Excerpt: "The argument that psychic powers come from the unused majority of the brain is based on the logical fallacy of the argument from ignorance. In this fallacy, lack of proof for a position (or simply lack of information) is used to try to support a particular claim. Even if it were true that the vast majority of the human mind is unused (which it clearly is not), that fact in no way implies that any extra capacity could somehow give people paranormal powers. This fallacy pops up all the time in paranormal claims, and is especially prevalent among UFO proponents. For example: Two people see a strange light in the sky. The first, a UFO believer, says, "See there! Can you explain that?" The skeptic replies that no, he can't. The UFO believer is gleeful. "Ha! You don't know what it is, so it must be aliens!" he says, arguing from ignorance."


In Wikipedia's article, "Human Brain," in the Popular Misconceptions section, it clearly states, "Humans use only 10% or less of their brain: Even though many mysteries of brain function persist, every part of the brain has a known function."
http://en.wikipedia.org/wiki/Human_brain#Popular_misconceptions


All in all, these articles pretty much say that the popular media and advertisment promoted this idea to help sell their products and make good stories. Nobody is quite sure where the myth first surfaced, although it is believed that some misinterpretation of scientific research occured somewhere down the line (or maybe some scientific research that ended up being refuted later on). Some are speculating the true meaning of using only 10% of your brain. Eric Chudler, Ph.D., states in his article, "What does it mean to 'use only 10% of your brain?' Does this statement imply that only 10% of the brain's neurons is active at any one time? If so, how could this be measured? Does the statement assume that only 10% of the brain is firing action potentials at one time? Even if this was true, the discharge of action potentials is not the only function of neurons. Neurons receive a constant barrage of signals from other neurons that result in postsynaptic potentials. Postsynaptic potentials do not always result in the generation of action potentials. Nevertheless, these neurons, even in the absence of generating action potentials, are active."

And regarding the questions that refer to MRI scans? Bull. MRI scans have only reinforced the fact that the Ten Percent thing is truely a myth. I'm not an expert on medical machines, but I would have to say that those pictures of MRI scans are only detecting a certain part of a brain function, like a certain chemical or electrical pulse. Like, press this button and you get the picture of where Chemical A is in the brain. Press that button, and you get the picture of where Chemical B is. Hopefully, you get the drift. "...a wide variety of new techniques have been developed to examine the brain — EEGs, CAT-, PET- and MRI- scans, magnetoencephalography, regional cerebral blood flow measures, etc. These show conclusively that the so-called "silent cortex" is anything but; rather than dealing with such visible tasks as motor functions, "silent" parts of the brain govern many subtle aspects of thought and personality. Scans show that no part of the brain ever goes "silent"; it may be used at different intensities, but even in the deepest sleep the brain continues to be active. It could hardly be otherwise. The brain consumes a large amount of the body's energy resources, meaning that an efficiently utilised brain is not only desirable but an evolutionary necessity. A mostly unused brain could never have evolved in the first place because of the wasteful overhead it would represent. Animals, humans included, have brains only as large as they require; that is why humans don't have whale-sized brains, for instance."
Excerpt from: http://www.solitarytrees.net/cowen/misc/tenperct.htm


If you want more information about the Ten Percent Myth, I'm sure you can find out just by googling it. :) Hope these links help! Fair winds.

Answer 2

Scientists don't say that because that is a urban legend. All of our brain is usable. That said, there are times when part of the brain is unused; like if your are in complete silence, then the part of the brain that analyzes speech to extract meaning does not have anything to do. In complete darkness, your visual cortex is out of work. The same way that you are not really using all of your arms muscle when you are riding a bicycle, and not using your leg muscle when typing on the computer; part of your brain is in use or not in use depending on the circumstances. But it is ALL usable and connected.

Answer 3

We only use 10% at a time. Scientists can use an MRI to determine brain activity.

Answer 4

Bad math. The actual idea is that we need 10% of our brains for the basic functions performed by all mammalian brains,

There is also the thought that 90% of the cells in the brain are glial cells and only 10% are nerve cells

Answer 5

It's more of, "we only use 10% of our brain at any given time".

They think this because:

When they put certain ions in the blood, they can use those ions to track where blood flows in the brain. The assumption is that active areas of the brain use more oxygen, and would require (& have) more blood-flow. And functional MRIs (fMRI) have shown that different parts of the brain have different relative amounts of blood for different tasks.

An example of a fMRI can be seen at http://pveout.area.na.cnr.it/***/fMRI2.jpg . The redder the colour in the picture, the more blood-flow.

Answer 6

yeah that is a myth. The brain uses more than 10%, depending what actiivty you are doing. The brain is extraordinary; it has many 'centers' that deal with different things. They know by hooping ou up to machines that measure brain activity..usually electrodes to the skull and electric readings are taken.

Answer 7

Let's compare it to a computer. I think that 10 % they are talking about might be permanent memories stored in your mind. The rest of your capacity could act as a kind of buffer or cache to process new information from your senses, shared memory of some sort?
Or maybe God made us this way so we'd never be obselete. We always have room for expansion.

Answer 8

They use only 10% of their brain.

Answer 9

we really use all of our brain, but you only use about 10% at a time. If yo never used a portion of your brain, then the nuerons in that area would die.

Answer 10

Scientists don't say that. The media, and mystics, say that.

And that's because it's not true.