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Mental Models

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In this article, I will explain what mental models actually are, why they are important, why just knowing these mental models is not going to make you smarter, and finally conclude with what is it that can make you smarter.

What is a mental model anyway?

Mental model is precisely what the name implies — a model that you build in your mind about something. For example, as you read this blog, you are building a mental model about the blog, and perhaps you are using that model to answer some questions (e.g. whether to subscribe to this blog or not, worth bookmarking or not). When you meet someone you start building a mental model, often in fact a flawed one, influenced by stereotypes. As you may have guessed, you are building mental models all the time.

Mental models affect how you function in the real world. Mental models are what you use to make decisions, and thus they affect your every action. If your food falls down on the floor, but you pick it up and eat it, you have a different mental model about hygiene as compared to someone who wouldn’t pick it up to eat.

What is a model?

A model is a representation of something. They are typically approximations of the real thing/system. More importantly, a model can be used to answer questions. A map, for example, is a model of the territory. The map is approximate (and that’s what actually makes it useful; if it was as accurate as the territory, then it is unwieldy and unusable). Maps can be used to answer specific questions, such as how to go from location A to B.

In the above example, your mental model of hygiene to decide whether to eat the falled food or not.

Why do we build mental models?

The human brain is a prediction engine. It is always trying to predict the outcome. In fact, as you walk, your brain is always predicting where your foot will land. If and when the prediction doesn’t match the actual outcome, the brain knows you are falling down.

So your brain relies on models to make predictions (or in other words, answer questions). And that’s why we are constantly building models to navigate this complex world. We have thousands (or who knows, perhaps millions) of models in our head. We can mix and match models to build new ones. Cars go fast. If a fast moving object hits a tree, one or both of those get damaged. You can use these two models to answer the question: What happens when a car hits a tree?

Importance of mental models

Why should we care? Since mental models are what you use to answer questions in your head (and to make decisions), the fidelity of your mental models determine how often you are correct. If you can be correct more often than others, that’s a real advantage. In contrast, if you have poor and inaccurate mental models, you are worse off than others and could cause harm. And for this reason, you have to carefully look into your head to see what kind of biases and irrational behavior you posses and try to get rid of them.

Suppose you are the CEO of a company. An important part of your job is to make decisions. Of course you can be data driven as much as you can, but the vast majority of decisions are going to be “use your intuition” kind of decisions. The term “use your intuition” is nothing but using your mental models. If you are constantly making poor decisions, the days are numbered for either your job or for the life of your company.

This is why good mental models are useful.

Some mental models are widely applicable.

While you may have many mental models that are unique to you and your experiences, there are other mental models that are widely useful. For example, compound interest is a really powerful mental model of how something grows (e.g. money, knowledge etc.).

My one hesitation is that, these are not really mental models to begin with. They are useful algorithms that you can internalize and make a mental model. For example, once you assimilate the idea of compound interest, it changes how you would think about money and investing. As an another example, something like Goodhart’s law, which sometimes gets quoted as one of the examples of mental models, is not really a mental model until you assimilate it. In reality it is yet another explanation of some portion of our complex world.

Knowing mental models is not enough

Recently I read a book called Super Thinking: The Big Book of Mental Models that listed 300+ mental models (incidentally the book is written by Gabriel Weinberg, the founder of DuckDuckGo and Lauren McCann). While I do recommend the book, I don’t think I am super-thinking yet. I could try to commit to memory all those 300+ mental models, but I suspect if I will ever become Warren Buffet or Charlie Munger, who are acclaimed masters of mental models.

Suppose you are preparing for coding interviews. If all you know is sorting algorithm, then you are going to have a tough time. Suppose you know all the different algorithms that there are, you will be in a much better position but might still not be able to ace it. You will need the ability to know where to apply what.

That’s why learning about these 300+ models is not the same as actually knowing them, from within.

Pay attention to mental representations for expertise

Let’s say you are a chess player. You want to get better at it. Learning all the different kind of mental models may be of marginal use to you. But what you really need is to sharpen the mental models you have built for Chess. Anders Ericsson calls this as mental representations.

The key is to build higher and higher level of mental representations.

As I explained in the article on deliberate practice:

Expert chess players, on the other hand, absorb in a lot more information — they see which pieces are weakly positioned vs. which ones are strongly positioned. They probably almost see a story that is playing out on the board. If you show a valid board, and then ask them to recall, they are able to recall very well. I, on the other hand, will struggle to recall a few pieces here and there. Also, interestingly, if you show an invalid board, with the pieces placed incorrectly, they will struggle to recall the board!

Mental representation allows you to improve the bandwidth of taking input and processing them. When I first started to learn about investing, I had no clue what any of the jargons meant. If someone explained an investing concept fast, I had trouble following. This is because I had no or poor mental representations and that hindered how fast I could understand things.

To me, mental representations hold the key to expertise. And deliberate practice helps you get there faster.

Warren Buffet when he was young, used to be immersed in company balance sheets. He read so many of them that he steadily kept improving his mental representation. He can probably download several GB worth of balance sheets into his head and process and spew out answers in a few seconds, all of which will take me several months. His bandwidth for processing balance sheets is much higher than mine. And as an investor he needs good mental representation of the world, which is where his reading of books help him. He is not just building mental models, but he is making them sharper and better.


We use mental models to navigate the world. So make sure to acquire good ones and throw away bad ones. If you are really interested in improving expertise, then pay attention to the mental representations you have.