Provoking thought

Human Behavior Demystified

I couldn’t fall asleep last night. I had an epiphany.

I grabbed my phone, opened SilverBullet and quickly jotted down a formula.

“I need to remember this in the morning,” I thought.

Little did I know that the morning was still far out. Plenty of time to start applying my new-found discovery to all aspects of my life. And only then I passed out.

What formula is that, you ask?

I formulated a mental model of human behavior.

That’s right. Using this model one can accurately explain, as well predict everything people do.

No biggie.

Before we go there, let’s start with a definition and a disclaimer.

First, what is a mental model? For this, we turn to Wikipedia:

mental model is an explanation of someone's thought process about how something works in the real world.

Clear enough. However, we should acknowledge the following:

“All models are wrong, but some are useful.”

This is an aphorism attributed to George Box back in 1976. I have to add this as a disclaimer for legal reasons.

Realistically though, George Box would probably change his mind hearing about this particular model. “… except for Zef’s mental model of human behavior,” he’d add, “that one is both correct and useful.”

Thanks George.

Without further ado, here it is — Zef’s mental model of human behavior:

Behavior = nature + personal history + context

Let’s unpack that a little bit.

First, note the = there, which implies a direct connection. This formula doesn’t say “behavior is probably influenced by the following factors (Waves hands in meaningful way.)” That would be weak. Instead it claims something much bolder: human behavior is fully deterministic, and a result of three variables, and these three variables alone.

Now we’re talkin’.

An observant reader may ask: “err, so where’s the free will variable in this formula?” Indeed, it is missing.

Let’s walk through each of the three variables in turn.


This variable in the formula is actually pretty constant. Unless we play the long game (think: evolution, natural selection), or are interested in genetic modification of some sort — we can basically consider this factor a given. We were born human (I’m speaking for myself here), our parents gave us a collection of genes. This combo plays a huge part in what we may or may not do at any given time. We may want to fight it, and we can try, but it will be hard.

It’s worth understanding our nature, less so trying to change it.

Personal history

This is effectively an event log of everything that has happened to us since conception. Conception? Yes, there is plenty of research that indicates that the person we become — and therefore the behavior that we expose — is influenced even by events that happen while we were still chillin’ in our mothers’ bellies.

All events since then affected our being, physically and psychologically. They changed our body, and trained our brain to this very point in time.

Yes, that’s a lot of events. A lot. Obviously not every event has an equal impact. Most events likely had barely any noticeable effect at all. Yet others changed the course of your life forever.

The cool thing about history is that we are constantly making it. The event of you reading this very article becomes part of your personal history a second from now. What will the effect on your behavior be?

Prediction: 🤯


This is the situation, the state of the universe, in which the behavior occurs or is triggered.

Somebody punches you in the mouth on a sunny Sunday afternoon on a playground.

You work at Meta, and you were just told on a video call that you were laid off.

You have your Vim editor open in a million-line legacy PHP code base and it is 3:22pm.

This affects what you’re going to do next.

The cool thing about context is that we can change a lot of it. You may start avoiding playgrounds on Sundays. You may want to decide to never in your life work at Meta. And you can switch to Emacs. Hypothetically.


To find out what anybody (including yours truly) is going to do next, we just add up these three variables and boom there it is: our behavior. Easy as that.

If we could rewind the tape, given the same inputs, we will get the same behavior again and again, and again. Why do people make that same poor life choice in your favorite drama series every time you rewatch the season? There’s your answer. “Don’t do it Jack, don’t do it! Noooooo! Again!?”

Obviously, in reality, we cannot rewind our tape, because the behaviors that happen become events in our personal (and other people’s) history, and will create a new context.

For example, the experience of being punched in the mouth may result in mouth-punch-avoiding behavior in the future (avoid play grounds on Sundays!). We call this “learning.” Also, in terms of context: the plan that we had before, is now gone.

While this all sounds nice and dandy, there’s an obvious concern that we need to address:

In practical terms it is unrealistic to determine accurate values for any of these variables. Therefore, it is also unrealistic to actually completely accurately predict behavior.

Sad trombone.

So… how is this useful anyway?

If you buy into this model (as you will once you accept its brilliance), you will realize there is little point in being upset about what people do (including yourself). People do things because of who they started out as, have become since, and the situation they’re put in now. That’s how things happen, and we just have to accept it.

If we don’t like the behavior we see in others or ourselves, we now have a framework to think about how we may go about changing it in the future.

Embracing this mental model gives us the tools to approach the problem in a constructive way.

Changing Nature

For example, we may be upset or angry about how people conform to others when they are in a group. We may hate how people say unhinged things when they are anonymous. We may be frustrated that people cannot factorize prime numbers in their head at the same speed that we can. However, these are all behaviors largely determined by human nature and genes. There are reasons people evolved to be this way over thousands of years. We may try to fight these things, and sometimes we should. However, very often our time and energy is better spent in accepting this nature variable as a constant, and focusing our energy on other variables. Perhaps it’s better to create a context where human nature is less tempted, for instance. Or allow people to use a computer to factorize their prime numbers, if that’s a thing you ever really need to actually do.

What helps us as managers, or humans sometimes interacting with other humans, is to learn as much about human nature and related topics as possible. This helps us better understand that perhaps this person isn’t evil, or stupid, or crazy, they are just human.


Understanding Personal History

We all grow up differently. Some of us are born into wealth; some into poverty. Some grow up in the middle of a war; some never will be close to one in their life time. Some will have had abusive parents or partners; some will have had no such thing.

Gabor Maté is a physician and author of books like The Myth of Normal, who pushes the idea of the importance of traumatic life events to the limit. Crudely put, his schtick is essentially “everything can be explained by trauma.” If we loosen the definition of trauma a bit to mean “impactful life events” we can see that this ideas is very compatible with our mental model. It is clear that important life event shape who we are and how we behave. And interestingly, or sadly perhaps, we may not always realize or even remember what those important life events are. Which, incidentally, is why psychologists have a job.

When I start to work with a new person, I always ask for their life story. I usually ask for this in a bit tongue-in-cheek way, but I feel it is valuable. The more complete of a picture I can build of a person, the more I believe I can understand them, and the more accurately I can predict how they will behave in the future.

The nice side effect of doing this is that it helps us realize that other people’s stories tend to be very different than our own, which affect their life priorities and decisions a lot. This helps us break out of naively thinking things like “well, money is not important to me, so it should not be important to anybody!” That’s easy to say for somebody who had never had to check their bank account balance in their life; less so for somebody whose parents had to work double shifts to pay rent.

Changing Personal History

The second reason why the personal history variable is a useful tool is that we can influence it. We can make an attempt to make something happen now that will change future behavior.

This may be as subtle as casually bringing up a topic during a conversation, which leads to the person to reflect on their life, learn something about themselves, and turn their life around. By switching from Vim to Emacs. Happens all the time.

It may also be done by punching somebody in the mouth on a Sunday afternoon. You had already tried asking them nicely to leave. You had already tried putting up signs. Yet they keep entering your garden and treat it like a playground. Perhaps a well-aimed punch is the language they understand and makes them never return. Perhaps violence is the answer.

But probably not.

Changing Context

This is the part I have most to say about, so I will try to keep it short.

People are shaped a lot by their environment. However, we tend to ignore this a lot of the time.

“Why do people not do what they’re supposed to?” we ask with a confused face.

I have questions:

How clearly do we set goals? How do we set goals? How much autonomy do we give people to achieve those goals? How often do we change these goals? What incentives do we give to achieve them? Who gets recognition? Who gets praise? Who do we promote? How do we promote? How do we hire? Who do we hire? How often do we let people go, and how do we explain it? How do we talk about people when they are not present? How often do we restructure the company? How do we respond when people ask a critical question during an all hands? Do we have a lot of processes? Do things need a lot of approvals? What is the quality of the coffee we serve?

This is just the tip of the ice berg in terms of questions whose answers shape the context we create for people to “do what they’re supposed to.” Especially if this “not doing what they’re supposed to” is a common problem, we need to question if this is not somehow related. Our mental model says it may well be.

Creating a context for people to be successful is 80% (random high percentage) of what the management job is all about.

Are we sure it’s not us who are not doing “what we’re supposed to?”

Asking for a friend.

So there you have it. Zef’s mental model for human behavior. It’s simple. It’s useful. It’s correct.

You are welcome.