Every now and then, I’ll come across a mention of the bouba/kiki effect, a classic study of sound symbolism that has been revisited several times over the years. The procedure involves
showing presenting experiment participants two shapes and two nonsense words, and asking them which word goes with which shape. One of the shapes is always spiky, the other bulbous, such as those shown here. One of the nonsense words consists of voiceless velar or coronal consonants and unround vowels, such as /kiki/. Variants have included the original /takete/, as well as /keiki, kʌte, kʌtiti,/ and /tite/. The other word consists of round vowels and voiced bilabial (usually) consonants, such as /buba, bamu, mabuma, maluma/, and the original /baluma/. As you have probably correctly guessed by now, most speakers tend to put the kiki-type word with the spiky shape, and the bouba-type words with the bulbous shape. “Right, because of the sounds of the word,” you may be saying. But how, exactly, because of the sounds of the word? Maybe it seems obvious to you, as it does to most people, that kiki just sounds like it belongs with something sharp and angular, and bouba with something balloony, but why, exactly?
I wondered: Are people taking their cue from the voiced or voiceless consonants? From the round or unround vowels? From the combination of unround vowels and voiceless velars, or round vowels with voiced bilabials? What would happen if I took kiki and bouba and just swapped the vowels in the two words, to get bibi and koka? What would people do then?
For the past few weeks, I’ve been finding out, running this experiment on my wife and sons, co-workers, fellow parents of members of the high-school marching band, and anyone else as opportunity arose. I’ve presented them with the shapes, drawn on a scrap of paper, and told them to imagine a previously undiscovered tribe of people, with no prior contact with any other civilization, and a language that seems to be unrelated to any known language. They have these two objects or shapes in their culture, and call one of them a bibi, and one a koka. Which is which? If you suspect that the consonants are the deciding factor, then the spiky shape should be the preferred koka, just as it is for kiki, and the globby shape should be the preferred bibi, just as it is for bouba. On the other hand, if you think it’s all about the vowels, then the spiky shape should be favored for bibi, and the rounded one for koka.
I’ve varied the order in which I presented the words, and the orientation of the paper when I show the shapes, to avoid bias based on order of presentation. Unfortunately, there are other sources of bias. After running my first three subjects (my wife, Doug, and Adam) by presenting the words on slips of paper, I realized that the angles of the letter k and the curves of the letter b might be a source of bias. Even now, this could still be a source of bias for literate participants, since they may imagine these words written down, but I couldn’t do much about that. (For a study involving pre-literate participants, see Maurer, Pathman and Mondloch (2006). I found it in the references for the Wikipedia article I cited above). In addition, by taking the most-popular words for this experiment, kiki and bouba, and making the minimal change of swapping their vowels, I’ve ended up with two words that actually do mean something in English. /koka/ can be a leaf, a carbonated drink, or of course, the Corpus of Contemporary American English. /bibi/ is a famous blues singer, an Israeli prime minister, a lovable droid, or the ammo for an official Red Ryder, carbine action, 200-shot, range model air rifle, with a compass in the stock and this thing that tells time. Any of these could provide associations that lead a subject to choose one shape or the other, but hopefully with a large enough sample size, they won’t matter.
So what happened? So far, my sample size is 27. Of them, 15 participants (55%) mapped bibi to the rounded shape, and koka to the angular one. The other 12 (44%) mapped bibi to the angular shape, and koka to the rounded one. So it looks like the consonants have a slight edge, but not much of one. In fact, if I throw out the data from my wife and sons, who were looking at written representations, only 12 participants mapped bibi to the rounded shape, and it’s now a 50-50 split. So maybe it’s the combination of vowels and consonants that produce the well-defined bouba/kiki effect, since it mostly disappeared when I flip-flopped the vowels.
There are other possibilities, too. Maurer et al., who hypothesized that the roundness or unroundness of the vowels was the important factor, mentioned that it could be that English or other languages have a detectable pattern whereby real words with rounded vowels (or spelled with round letters) denote round things, and real words with unround vowels refer to pointy things. For support, they point out that there has been one study where the kiki/bouba effect did not show up, involving the Songe people of Papua New Guinea. Maybe, they note, this language doesn’t have the same kind of previously existing sound/shape correspondences. This was why Maurer et al. wanted to do their experiment on very young children, who hadn’t had as much exposure to their native languages.
More intriguingly, Maurer et al. suggest that “the effect is stronger for some consonant/vowel pairings than others” (p. 320). They suggest this because in just one out of their four pairs of nonsense words, one word contained voiced velars and round vowels–in other words, the same combination I had in koka that I didn’t think other researchers had looked at. Their word was /goga/, and for the pair /goga, tite/, they did not get the clean mapping that they got with the other words. (They also suggested that it could have been a problem in the story that they told their toddler subjects for this particular pair of words.)
So that’s my bibi/koka experiment. If you try it on your friends or family, let me know how it goes.