Where personality comes from

When we talk about “personality”, what we’re really talking about is “variance in human behaviour”. Why do people think and act differently from each other? What makes two people, faced with the exact same situation, respond in completely different ways?

A lot of people believe that differences in behaviour come down to a combination of environment and physiology. And there’s a lot of truth to that. The signals we get from the outside world, as well as our own bodies influence our thoughts and actions in some pretty major ways.

But there’s also a part of us that seems to be innate, and unrelated to those things. Anyone who’s a parent will tell you their kids came out of the womb with their personalities intact. And siblings, who grow up in the same household, will often have wildly different ways of relating to the world.

I can personally attest to this — my brother and I, raised under the same roof with the same parents, couldn’t be more different in what we value and how we approach our lives. He’s measured, systematic, and disciplined, and he structures his life around stability. I’m basically a chaos monkey, driven by creativity and passion.

Why is that? Where do these differences that seem to have nothing to do with our environment or physiology come from?

The origins of personality theory

The first person to study personality in any formalized, scientific sort of way, was Carl Jung. He saw a lot of patients as a psychiatrist, and over the years, began to notice distinct patterns in how people processed and evaluated information. This formed the basis of his theory of personality.

As far as Jung was concerned, personality (differences in how people chose to act in their lives) came from differences in how they naturally preferred to use the mental processes of perception and judgement.

Perception, in a nutshell, is what you see. How do you take in information? What do you focus on? What do you need to know to feel like you “understand” something?

Judgement is how you make decisions. Essentially, how you “evaluate” the information you’ve received. How you choose to act on it.

In Jung’s model, perception + judgement = behaviour.

Which makes sense. In any given situation, what you think is going on + whether you think that’s good or bad (dangerous or safe, etc. etc.) determines how you act.

If you were a prehistoric caveman, walking along a stretch of woodland, you would:

• first have to notice the grizzly bear droppings under a tree
• then understand that grizzly bear droppings under a tree means that there is a grizzly bear around
• then evaluate that grizzly bear around = danger
• and then decide to run.

In this example, we could say the first two steps (noticing and understanding) are using your perceptive process and the last two steps (evaluating and deciding) are using your judging process.

Every human being (and I would honestly venture to say every living thing with sensory organs and a brain) uses perception and judgment exactly like how I’ve described to engage with their environment and to survive.

Where things get more complicated is that humans actually have two different ways they can perceive things, and two different ways they can judge them. So instead of one process for perception, one process for judgment, it’s two processes for perception and two for judgement. Four in total.

Jung calls these cognitive functions. If you’ve heard that term thrown around, that’s what it means.

Cognitive functions = the four mental processes used for perception and judgment.

And everyone has all four and uses all four. Needs all four to make sense of the world and stay alive. BUT, and this is where things actually get complicated, every person has an innate preference for one of the perceptive functions and one of the judging functions over the other.

This means that throughout their life, everyone has a “dominant” way they perceive and a “dominant” way they judge. Kind of like how everyone’s either right-handed or left-handed.

And because people’s dominant processes are different, they end up perceiving and judging their environment in different ways, resulting in …

You guessed it — variance in behaviour, a.k.a. personality.

Thanks for reading! In next week’s issue, I’ll talk about the specific cognitive functions that make up perception and judgment + how each one of them impacts personality.

In the meantime, if you like nerding out about psychology (and potentially other human-related things) check out my Substack and feel free to subscribe 😁!