LUKE GROSKIN: Which of these shapes
is Bouba and which is Kiki?
SPEAKER 2: What?
SPEAKER 3: Bouba or Kiki?
SPEAKER 4: What's a Bouba?
And what's a Kiki?
LUKE GROSKIN: They're just made up words.
So which shape looks like Bouba, and which
shape looks like a Kiki?
SPEAKER 5: This one is Bouba.
And this one is Kiki?
SPEAKER 6: This is Bouba.
And this is Kiki.
SPEAKER 7: Bouba.
And Kiki.
SPEAKER 8: Bouba, to me, maybe a splash, you know?
Kiki, I don't know.
Maybe something shiny like a key ring, you know?
SPEAKER 9: This one is Kiki.
And this one is Bouba.
LUKE GROSKIN: You're not alone if you thought this one was
Bouba and this one was Kiki.
In fact--
KELLY MCCORMICK: Upwards of 90% of the groups tested
will reliably match Kiki the jagged shape and Bouba
to the rounded shape.
LUKE GROSKIN: But no matter where it's tested
or what language it's tested in, researchers
see the Bouba-Kiki effect.
KELLY MCCORMICK: The effect was originally
documented by Wolfgang Kohler in the 1920s
with Spanish-speaking population.
And since then, it's been taken all over the world.
LUKE GROSKIN: Including preschool.
KELLY MCCORMICK: It's been conducted on toddlers,
and a similar effect was observed.
LUKE GROSKIN: So what's going on?
SPEAKER 10: I don't know.
It just looks like it.
SPEAKER 11: Come on, look at the curves and the-- just looks
like a Bouba, man.
It's like a Bouba.
LUKE GROSKIN: But there's got to be
a better explanation than that.
Kelly McCormick of Emory University
riffs on some of the popular theories.
KELLY MCCORMICK: 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," your lips are rounded,
your oral cavity is very open.
Bouba.
Nothing tense or linear or tight about it,
as there is when you say "Kiki."
Kiki.
It could also be something that arises
over the course of experience.
Maybe were 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 "whoa, whoa,
whoa."
And the pine cone's going to be more like "t-t-t-t."
LUKE GROSKIN: But the Bouba-Kiki effect
is really just a roundabout way of answering
a more pointed question.
KELLY MCCORMICK: At the heart of it,
we're really asking why certain sounds are
especially good for representing certain meanings.
So 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?
LUKE GROSKIN: And word after word, you
can narrow in on the exact sounds that convey a meaning.
KELLY MCCORMICK: 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.
LUKE GROSKIN: And on the opposite side of the spectrum?
KELLY MCCORMICK: "Nolu, Mumo, Lomo."
These are all characterized by sonarant 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.
LUKE GROSKIN: 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.
SPEAKER 11: I just know this is a Bouba.
This is Bouba, man.
LUKE GROSKIN: For Science Friday, I'm Luke Groskin.