Why sharp shapes are "kiki" and round ones are "bouba"
In 1929, psychologist Wolfgang Köhler showed people an angular shape and a curvy shape, asking which was "baluba" and which was "takete." Later studies used "bouba" and "kiki." Over 95% of people, regardless of their native language or writing system, map the jagged shape to "kiki" and the rounded shape to "bouba." This suggests human brains map visual shapes to speech sounds in non-arbitrary ways.
The Island Experiment That Challenged Linguistic Dogma
In 1929, German psychologist Wolfgang Köhler conducted a simple experiment while working on the island of Tenerife. He drew two abstract shapes on a sheet of paper: one was an undulating, rounded form with smooth curves, and the other was a jagged, spiky figure full of sharp angles. Köhler presented these figures to Spanish-speaking participants and asked them to decide which shape was named 'takete' and which was named 'baluba' (often referenced in later literature as 'maluma'). Despite having no prior exposure to these nonsense words, the overwhelming majority of participants matched the sharp, jagged shape with 'takete' and the soft, rounded shape with 'baluba.'
More than seven decades later, neuroscientists Vilayanur S. Ramachandran and Edward Hubbard revived and modified Köhler's paradigm to investigate multisensory perception. Using the nonsense words 'bouba' and 'kiki,' they presented similar jagged and rounded figures to native English speakers in the United States and native Tamil speakers in India. In both cultural groups, between 95% and 98% of participants designated the jagged, star-like shape as 'kiki' and the soft, organic form as 'bouba.' The striking consistency across radically different languages and writing systems demonstrated that the association was not a byproduct of cultural convention or alphabetical orthography.
The phenomenon, now widely known as the bouba/kiki effect, directly challenged one of the foundational principles of modern linguistics: Ferdinand de Saussure's assertion that the relationship between the sound of a word and its meaning is fundamentally arbitrary. For decades, linguists maintained that nothing about the acoustic structure of the word 'dog' inherently connected it to a canine, arguing that words are purely social conventions. The bouba/kiki effect proved that under certain conditions, human minds possess built-in biases that systematically pair specific acoustic properties with specific visual geometries.