How and why do we associate words with shapes?

For decades, studies have shown that certain people across languages associate words with shapes. Science Friday investigates what makes a word seem round or spiky.


Which of these shapes is Bouba, and which is Kiki?


[ Laughs ]

Bouba or Kiki?

What's a Bouba, what's a Kiki?

They're just made-up words.

So which shape looks like Bouba, and which shape looks like a Kiki?

This one is Bouba, and this one is Kiki.

This is Bouba, and this is Kiki.


And Kiki.

Bouba to me, maybe a splash.

You know, Kiki, I don't know, maybe something shiny, like a key ring, you know.

This one is Kiki!

And this one is Bouba.

You're not alone if you thought this one was Bouba and this one was Kiki.

In fact...

Upwards of 90% of the groups tested will reliably match Kiki to the jagged shape and Bouba to the rounded shape.

And no matter where it's tested or what language it's tested in, researchers see the Bouba-Kiki effect.

The effect was originally documented by Wolfgang Kohler in the 1920s with Spanish-speaking populations.

And then since then, it's been taken all over the world.

Including preschool.

It's been conducted on toddlers, and a similar effect was observed.

So what's going on?

I don't know.

It just looks like it.

Come on, look at the curves and the -- it just looks like a Bouba, man.

It could -- it's like a Bouba.

But there's got to be a better explanation than that.

Kelly McCormick of Emory University riffs on some of the popular theories.

Some people do think that we're all a little bit synesthetic -- that we're associating audio and visual information because we have kind of a wiring between auditory and visual parts of the brain.

Maybe it's the shape our mouths are making as we're pronouncing these words that causes us to associate.

So when you say the word 'Bouba,' you're lips are rounded, your oral cavity is very open.


Nothing tense or linear or tight about it as there is when you say 'Kiki.'


It could also be something that arises over the course of experience.

Maybe we're kind of simulating what it would be like to interact with something of these different forms.

Take a bowling ball and a pine cone, and you roll them across the ground.

The bowling ball is going to have this kind of... [ Makes warbling sound ] [ Rumbling ] And the pine cone's gonna be more like... [ Makes ticking sound ] [ Clicking ]

But the Bouba-Kiki effect is really just a roundabout way of answering a more pointed question.

At the heart of it, we're really asking why certain sounds are especially good for representing certain meanings.

The one thing that we've done is make hundreds and hundreds of nonsense words and done kind of a playoffs.

Hey, which of these do you prefer?

Is this a good word for pointed?

Is this a good word for roundedness?

And word after word, you can narrow in on the exact sounds that convey a meaning.

Words like 'Tekae,' 'Ketae,' 'Teetae' were most likely to be rated as sounding extremely pointed.

And those are words with very abrupt transitions in the sounds.

And on the opposite side of the spectrum...

'Nolu,' 'Mumo,' 'Lomo' -- These are all characterized by sonorant consonants.

Their voiced consonants, and they all have rounded vowels.

By figuring out what it is about specific words that's driving the effect, we can come up with a better account of what kind of cross-sensory mappings might be driving it.

So whether it's just the way we make a sound... or we learn to associate that sound with a concept or we're just wired weird, you can be certain this is not all nonsense.

I just know this is a Bouba.

This is Bouba, man!