4 Common Brain Myths…Explained!

Morgan Freeman has been really getting on my nerves this week. I’ll be sitting in my lounge going about my evening, and suddenly his smooth baritone voice will interrupt my thoughts/dinner/internet browsing with the statement:

‘It is estimated that us human beings only use 10% of our brain’s capacity. Imagine if we could access 100%!’  

I start internally screaming. The belief that we only use 10% of our brains is one of the most pervasive and prevalent neuroscience myths, but it’s just not true! Of course, I understand that this statement is part of a Hollywood film script and will typically be considered as fiction, but it has prompted me to address just a few of the most common misconceptions about the brain for this week’s post:


  1. We only use 10% of our brains.


Nope. No. Nu-uh. Not true. We use the whole 100% of our brain. If we used only 10%, then we’d perhaps expect injuries caused by physical trauma, stroke or disease to have little or no effect, unless they hit the ‘functional’ 10%. In reality, loss or damage to even small areas of the brain can greatly, sometimes devastatingly, affect a person’s life and how they function. From an evolutionary point of view, it would make no sense for us to develop such large and complicated organs in our heads if the majority of it is useless. Modern imaging techniques have also confirmed that there is activity throughout the entire brain, even while we sleep.

So if there isn’t even a grain of truth to this statement, where did it come from, and why do people still believe it?

I haven’t been able to find one absolute initiation point for this belief. However, it may have resulted from very early experiments in animals, where it was found that simple tasks could still be completed after damaging pretty large areas of their brains, leading some to believe that there was a lot of redundant stuff in our heads. Alternatively, it has also been claimed that the statement ‘We are making use of only a small part of our possible mental and physical resources’ by prominent psychologist William James in 1908 may have initiated the idea that we are not making full use of our brains. Misinterpretation and misquoting over the years gradually morphed into the ‘10%’ myth we know (and loathe) today!

But why do we still believe it? Well it seems to have become ingrained in popular culture – it is repeated so commonly and mentioned so frequently in passing (à la Morgan Freeman), as well as in advertisements for self-improvement (e.g. brain-training) that it may simply be accepted as true.


  1. Fish have a three-second memory


Again, no! Fish are more complicated and highly developed creatures than previously thought. A 2009 study demonstrated that not only could fish associate a specific noise with feeding time (in the same way as Pavlov’s famous bell = food experiment in dogs), but that this association was remembered three months later. In fact there has also been a study that has demonstrated that fish may have emotional states, and can learn that a particular environment is associated with a food reward, and another is associated with being chased by a net – when given the choice, fish spent more time in the environment with the food reward, and avoided the scary side! Even more astonishingly, fish have been found to be able to learn the difference between blues and classical music, and can even classify music they have never heard before into one of these two categories. And these aren’t the only examples of fantastic fish memory – the internet is full of different experiments and studies about fish learning and memory – take a look!

But if fish are so clever, where did the three-second myth come from?

There doesn’t appear to be a definitive source for this myth, but it has been suggested that it may have arisen to justify the small bowls that goldfish are commonly kept in – if they have such short memories, then they can’t get bored, and there’s no need to feel guilty! If anyone has a better answer for where this myth began, please let me know!


  1. Drinking alcohol kills your brain cells


If this were entirely true, then there would be very few Freshers that would ever manage to graduate from their undergraduate degrees (or indeed make it past Fresher’s week). It appears that in the short term, acute alcohol intake (i.e. binge drinking) will not kill your brain cells – it alters how brain cells communicate with each other, causes dehydration and reduces glucose metabolism (their use of energy), but these functions can be restored following a period of abstinence. A study in 1993 also failed to find any difference between the number of neurons in the brains of alcoholics and non-alcoholics.

However, there is some more recent evidence that chronic alcohol abuse may lead to neurodegeneration, although exactly how this happens isn’t completely understood, and it may be a combination of cell death and dysfunction. However, excessive consumption of alcohol over a long period of time is able to indirectly lead to the death of brain cells – chronic alcoholism may lead to severe vitamin B deficiency, which is the cause of Korsakoff’s disease; a form of dementia associated with memory loss and confusion.

As we have a surviving and intelligent graduate population, where did the belief that alcohol kills brain cells come from?

Most likely, this belief has quite simply arisen from the ridiculous behaviour, slowed cognition and terrible decisions exhibited by drunk people, combined with the agony of a really bad hangover!


  1. Vaccinations cause Autism

NO. NO. I cannot stress this enough – THIS IS NOT TRUE. When deciding which myths I was going to include in this post, I chose to tackle this one as its propagation has been so damaging to children’s health – in fact it has been described as ‘the most damaging medical hoax of the last 100 years.’ 

There have been (and still are) several theories put forward to describe why the MMR (measles, mumps and rubella) vaccination would cause Autism – these have included the overwhelming of an infant’s immune system, the inclusion of toxic ingredients in the vaccine, and the vaccine causing damage to the intestinal walls which allows infection by disease-causing proteins. All of these have subsequently been tested, and none of them are true.

There have now been multiple studies that have demonstrated no causal link between the MMR vaccination and the development of Autism or other Autism spectrum disorders. This paper by Gerber & Offit (2009) summarises the work and reviews the evidence, and an analysis released this year re-states the fact that there is no association between the MMR and Autism.

But if there is absolutely no link between Autism and the MMR, why do so many people believe it, and why is it still going strong?

In contrast to the other three myths I write about here, there is one very definite source for this belief. It started with a fraudulent paper published in a medical journal in 1998 by author Andrew Wakefield – he noticed that a few children coincidentally exhibited some autistic-like behaviour shortly after receiving the MMR vaccination, and that they also had intestinal troubles. However, only 12 children were studied, and behavioural symptoms of Autism tend to appear around the same age as the MMR is typically given, so it is no surprise that these two events appeared close together in these children. Furthermore, there were multiple issues with the work – in 2010 the paper was fully retracted, and in 2011 a description of the fraudulent activity was published in the British Medical Journal.

But why do people still believe that there is a link? Parents are understandably very protective of their children and do not want to cause them any harm, and the doubt and fear over vaccines that occurred in response to the original paper is still enough to stop some parents from getting their child vaccinated – in these cases, it may be a lack of information about where the risks and dangers really lie that affects their decision. There is also a strong anti-vaccination movement that existed prior to the fraudulent paper, so the findings from this paper have been used as ‘evidence’ for that movement and strengthened their position, despite evidence to the contrary.


Are there any other myths about the brain that you are interested in knowing more about? Is there something you’ve heard in the office that you think might not be true? Just ask in the comments section below!


The Biocheminist


References & for more, see:               

10% myth:




Fish myth:






Alcohol myth:





Vaccine myth:









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