Answer: The kiki / bouba effect is a psychological phenomenon in linguistics where a person associates the word “kiki” with jagged shapes and “bouba” with rounded shapes.
The kiki-bouba test, or kiki / bouba effect, is a test in psychology that examines a person's association between certain sounds in language and types of shapes. In the kiki bouba test, a subject may be shown two irregular, abstract shapes. Usually, the shapes are shown in monochrome, either gray or black. One of these shapes has sharp, spiky corners, while the other has more rounded, curved shapes. Then, the subject would be asked which shape was named “kiki” and which shape was named “bouba.” These nonsense names were chosen since they are likely words that no subject has seen before, and therefore do not have any other associations with round or jagged shapes.
More than 95% of the subjects agreed that the jagged shape was named kiki, while the rounded shape was named bouba. This phenomenon was initially observed across two different groups, American undergraduates and native Tamil speakers in India. This experiment was put together by Vilayanur S. Ramachandran and Edward Hubbard in 2001. In their interpretation of the results, the shape of the figure most closely mimics the shape of the mouth. In “kiki,” the closeness of the tongue with the roof of the mouth is a smaller, sharper shape, while “bouba” requires a very open shape with the tongue dropped low.
There is some evidence that the consonants are more significant that the vowels in contributing to the kiki-bouba effect. In one experiment, subjects were shown different pairs of consonant-vowel pairs. Words containing harder consonants, such as “k” or “t”, became associated more frequently with the sharper shaped image compared to the soft sounding consonants like “l” or “m”. These consonants were more important in determining the shape compared to the vowels in between those letters (Consonants are More Important than Vowels in the Bouba-kiki Effect).
A similar experiment was initially described by the psychologist Wolfgang Kohler in 1929. In this original experiment, subjects were again shown the two abstract shapes, but they were asked to choose from the names “taketi” or “baluba.” Just as with Ramachandran’s experiment, the harsher sounding “taketi” was associated with the sharp shapes, while the softer sounding “baluba” was more often paired with the round shapes.
The major implication of the experiment is that items are not named arbitrarily, but are rather named based on the mouth shapes that are made. A second implication is that names are physically correlated with the sounds. Harder objects resonate at higher frequencies and are more likely to break into sharp, jagged pieces. On the other hand, softer objects resonate at low frequency and are less likely to shatter.