So what we have is just a standard family portrait, some smiling cat, masterfully drawn rainbows and flowers, and then there's this.

It's my name written completely backward.

Weird, right?

Except I used to do this all the time.

If it wasn't my full name, it was usually just a random letter or number, like I did with the 'G' in kindergarten.

It's called mirror writing, and most kids under the age of seven have done it at some point, in some form.

It seems kind of ridiculous now, but it's completely normal.

It's just a sign of how our brains evolved to see the world.

Learning to write is kind of hard.

First, we have to understand a string of abstract shapes, then, as we learn, we have to understand that, in English, script goes from left to right.

Early on, before really understanding which direction to write in, kids like me just wrote where there was empty space available.

So if I put a 'K' on the right edge of the page, I just wrote the rest of my name into the empty space on the left.

I would be willing to bet that you started with the letter "K" because you know that "K" is the first letter of your name, and they progressed in the right-to-left direction – writing the "K" backwards, the "I" and the "M" would also be written backwards, but we don't see that because they look exactly the same.

Rob McIntosh has studied various forms of mirror writing for years.

Much more common, actually, is just partial mirror writing.

Where the script might go in the correct direction, but individual letters will be reversed.

So maybe the letter "D" is written as a "B" or "B" is written as a "D."

You might be thinking, "So what? Kids are still learning and just don't understand the shapes yet."

But it's not likely for a kid to take that same letter and flip it completely upside down.

And we're not talking about them confusing one letter for another entirely.

Remember, I didn't use the wrong shapes.

I used the right ones.

In the right order – just backward.

So, how did I manage to do that?

The short answer is that children can't tell these mirror images apart at this stage.

You know, we tend to think that children are bad at discriminating the mirror images, but we might turn that around and say that actually that children are very good at generalizing across mirror image forms.

And it seems to be that that's something the human brain is set up do.

There's a name for this inability to tell mirror images apart: "mirror generalization" and our adult minds do it all the time too.

Think of the Statue of Liberty

You can probably picture that it's a green statue that holds a torch but...

-What hand is the torch in?

-I'm trying to think... if I picture...

-Oh, God.

-Oh, I have no idea.

-I mean 50/50 guess, I'm gonna say the right hand.

-Left?

-Torch is in the right hand.

-Left.

-Are you sure?

-No.

And you can probably describe the Apple logo.

-A silhouette of an apple with a bite mark out of it ...

But –

-Which side is the bite taken out of?

-Oh my god. I look at this every single day.

-If I'm looking at it?

-Yeah.

-It's on the left side of the Apple.

-I want to say the right side.

-Uh, the left side.

-The left side.

The trouble is that orientation as in the left or right direction something is facing is rarely committed to memory.

Because in the natural world, it doesn't really matter.

When we see an animal facing to the left, we'll still recognize it as a dog when it turns around.

When I'm sitting to the right of someone, I'm not suddenly shocked when they turn to face me or move to my left.

Most objects in nature don't change their identity depending on which way round they're facing.

Trees, plants, and animals basically look the same one way or another.

So our brains cut corners to allow us to recognize these things quickly and commit them to memory without focusing on direction.

So when it comes to letters and numbers and other things that depend on orientation, we have to work a little harder to remember which way is right.

We have to sort of suppress the tendency to automatically generalize.

Which is actually an amazing feat.

Our brains have evolved to mirror generalize, and we've taught them when and how to turn that skill off.