“The Big Brain Filter”

Jacob Lennheden
Published in
7 min readSep 27, 2016


— The reason you don’t go insane (and others do)

Prior to Mike Tysons’ encounter with Evander Holyfield, the prize for the most famous earless man in history probably goes to Vincent Van Gogh. Rumor has it that he was depressed and hallucinating when he in a state of lunacy cut of his own ear. Yet, Van Gogh was also deemed one of the most creative artistic geniuses of his time. And if you spend some time googling “creativity & insanity” will you find millions of pages highlighting this apparent correlation. See this one for instance.

That the border between “insane” and “genius” is very thin has been known since antiquity and is not a particularly controversial finding. Today most psychologist agrees that people who are more creative, are also to a larger degree predisposed for certain mental ailments. But why is that and what exactly goes on in the brain? In this post I will try to explain why the border between creative genius and bat shit crazy is so narrow, and also give some pointers that can help you understand creativity more in general.

This is where the title of this post, or what I call “the big brain filter” comes into the picture. The name in academia for this big brain filter is “Cognitive Inhibition” — and this is responsible for filtering out irrelevant information to avoid information overload. But let’s face it, in 30 seconds you will have forgotten the word “Cognitive Inhibition” — or at least forgotten what it does — so let’s just stick to “the big brain filter”.

To understand how this work we need to go back to some basic neurology. In this sense it’s not completely off to use a smartphone or a modern day computer as an analogy for how the brain works.

So, the human body has 5 key senses that provide “inputs” in terms of information. These are ears, (sound input), eyes (visual input), skin (haptic input), nose (smelling), and tongue (taste). Unlike a computer however, the human body cannot turn off these sensors.

You can’t just turn off your ears or turn off your eyes in the same way you can turn off the mic or the speakers on your laptop (Though apparently, according to a recent post by Mark Zuckerberg, we can’t really turn off the laptop Camera or Speakers either). Thus, every bit of sound that is created near us (and mind you, sound is just waves that enter the ear — read this amazing post to learn more: http://waitbutwhy.com/2016/03/sound.html), enters the ear channel whether we want it or not. It goes in, is translated to an electric feed in one part of the brain (enter part) and is sent up to the big brain filter that decides what part of information is relevant here.

To illustrate how the filter works imagine the following situation: You are sitting at a busy restaurant and having a conversation with a person across from you. You clearly hear everything that goes on in the room. The soundwaves are clearly entering your ear — but the big brain filter steps in to filter all the irrelevant noise away so you only hear what the person in front of you is saying. This is the same reason you can read a book while the TV is on. The brain simple “turns off” the sound from the TV.

The same thing is the case with eyes, nose, ears, tongue. The big brain filter is clearly aware that you are wearing clothes, or that the sun strikes your skin and creates thermal heat — but it is not something you consciously think about. And this is a good thing.

In other words, the brain is built such that only relevant information is fed into the conscious part of the brain — and irrelevant information is filtered away. Thus, under normal circumstances the filter serves the very practical purpose of focusing our attention where attention is needed. Let’s take an example. See the image below.

Consider yourself walking around on the Savannah on a sunny day. Sky is clear. Hummingbirds are flying around. You have a cold diet coke with you and a bag of Mentos. You ate something bad last night and your stomach feels a bit funny….Then, BOOM! Suddenly out of nowhere a big hungry lion shows up! In this case the filter discreetly and effectively steps in and focus your attention on the lion. Thus, perhaps you forgot to buy toilet paper this morning and wonder how you will cope if your rumbling stomach gets worse. Relevant when you are staring into the eyes of a hungry lion? Not really. So that thought gets filtered away. Lion! Ah, like in the Lion King. You LOVE Pumba. But well, that’s association is not really relevant either when a hungry lion is approaching you. So that also gets filtered away. Danger? Well — yes, you are in danger. That is definitely relevant! This thought goes to your brain. Danger is associated with drugs. Is your cousin okay in rehab? Irrelevant when you are about to be eaten by a lion. The sun is burning on your skin. Should you use sunscreen? Not a thought that even remotely enters your brain. It’s completely filtered away. Run Away? — Well, if you don’t want to get eaten perhaps you should get out of there in a heartbeat. So that thought makes it to your brain.

This is obviously very oversimplified — but in general this is how the mind works.

The brain has a big filter that filters irrelevant information away, so we focus on what’s relevant and also don’t spend an unnecessary amount of energy. The brain uses an enourmous amounts of energy just to function — and like a muscle (even though it’s not) it can get tired or depleted of energy. To conserve energy it is designed such that seemingly irrelevant information is not processed. Sort of like a car that turns of the engine when it’s not driving or a computer that goes into power saving mode when not being actively used.

While everyone has this filter, we don’t all have the same degree of filter. Some people filter away more things than others. And this filter is one of the keys to understanding why some people are more creative than others. The process of creativity in the brain is to connect different concepts into something new and useful. This happens through our association network (as described on the Savannah with the lion) — and the more remote these associations are the more creative do we perceive the solutions to be. More creative people generally have a lower filter — meaning more “concepts” enters their conscious part of the brain and they have an easier time connecting very remote concepts and see solutions that they rest of us don’t. (Again, thinking of the Savannah example, the creative person would perhaps remember that running from a Lion invokes the Lion’s hunting instinct, so the best thing to do would be to stand tall, add the mentos to the coke and throw it in the direction of the lion to scare it away)

However, without this filter, we would behave a bit like a PC from the 90’s when someone opened too many windows and programs at once. We would have information overload and crash.

And this is kinda what sometimes happens to very very creative people. They get too much information in and well, go nuts. However, there is another aspect to this and that is what is roughly called brain capacity. It’s a lot more complicated than this in reality, but to simplify things think of two factors. 1: Filter. 2: Brain Capacity. Very creative people (that are not insane) usually also have a very high intelligence. This means they can handle and process all the extra information or “concepts” that goes through their filter and turn it into something useful, and simply increase the filter when they don’t want too much information and then lower it when they want to be creative. An analogy would be to have a very fast computer that allows you to open several programs and windows at once. In the very artistic graph below I have tried to explain what this means.

So most of us are relatively smart and have a moderate to high filter. We get good ideas sometimes, don’t go insane, and get by with our lives just fine. Then there are the creative geniuses. They have a very low filter, so they get tons of information and easily make remote associations. BUT, they also have a very high IQ or “brain Capacity” that enables them to handle all this extra information and put it to good and productive use.

Then we have the “insane” category. This category has a low filter like the geniuses, but their IQ is not high enough to handle all the information and the information overload leads to mental challenges. Again, this is simplified and there are many other causes for mental illness. But at least now it should make more sense what some of the science behind the whole genius vs mad debate is all about.



Jacob Lennheden

Nomad, researcher, writer, social entrepreneur. I specialise in the intersection of technology and society. Helping decision-makers navigate uncertain futures.