It's sort of like what happens when you're tripping.

[Do you have synesthesia?]

Different parts of your brain control the sensation of the perception of vision, or of hearing, or of smell, or of taste, and a lot of those areas in the brain are neighbors.

My name is Nadia Ortelt, and I'm a DIY neuroscientist.

In some people, the connection between those neighboring areas is much stronger than in other people, and those people have synesthesia.

They can see colors associated with numbers, or shapes, or letters, or words.

I'm Jordan.

I'm Justin.

And we both have synesthesia, and we're dating.

Well, I see every letter has a color, and every number has a color.

So, I had it my whole life, and I thought it was totally normal to associate colors and numbers and letters in my head.

All my numbers are...they kind of correspond with the rainbow.

I have, like, ideas about, like, the personality of numbers.

"Seven" is kind of a jerk.

"Three" is like a really nice guy.

It's a good number.

People with synesthesia are usually much better at memorizing things.

Because they always have two associations with every idea, or object, or thing.

I remember distinctly like when I was a little kid remembering my phone number, my first phone number, with colors.

Green, green, gold, red, red, gold, gold.

My name's actually really ugly.

I don't like the way it looks.

It is estimated that 1 in 200 people might have some form of synesthesia.

Synesthesia is actually a really common condition, but also it's how our brains work most of the time.

So you can do this really simple experiment at home to see what synesthesia actually looks like.

Cut out a bunch of shapes, some like this, that are kind of pointy and spiky, and some like this, which are round and a bit softer.

Put all these shapes in front of your friend, and ask them to associate the two of them with one of two categories.

One which is a nonsense word "Kiki," and the other which is a nonsense word "Bouba.".

Who are "Kiki" and "Bouba"?

They're like Miyazaki characters.

"Kiki" kind of sounds like spiky and sharp, and "Bouba" kind of sounds round and soft.

And you'll find that actually everybody associates these types of shapes with "Kiki," and these types of shapes with "Bouba.".

Everyone feels this way?

That's creepy.

No, that's not how it works.

Is that how it works?

I have no control over my mind.

Oh, that looks exactly like what I did.

I guess everyone has a little bit of synesthesia in them.

Wow!