Almost Everyone Calls the Spiky Shape 'Kiki'

Wolfgang Kohler ran the original test on Tenerife sometime before 1929 and tucked it into his book Gestalt Psychology. He drew two shapes — one rounded, one jagged — and asked which was takete and which was maluma. The answers came back the same way over and over: spiky was takete, round was maluma.

In 2001, V. S. Ramachandran and Edward Hubbard at UC San Diego ran a cleaner version with new words, bouba and kiki. Across English speakers and Tamil speakers in India, about 95% of subjects gave the same pairing — bouba for the round blob, kiki for the star. The names had stuck to the shapes again, in two languages that share neither writing system nor sound inventory.

The obvious reply is that this is just an artifact of how the letters look — the curve of a 'B', the points of a 'K'. So in 2013 a team led by Suzy Styles tested 4-month-old infants who can't read or speak. The babies looked longer at mismatched pairings, the standard infant tell for 'something is off here.' Whatever the mechanism is, it shows up before literacy.

The biggest test came in 2022, when a group led by Aleksandra Cwiek ran the experiment on 917 speakers across 25 languages and 10 writing systems — including Mandarin, Georgian, Arabic, Korean. Most languages produced a clear bouba/kiki split, though the strength varied. The effect isn't universal in the strict sense, but it's the closest thing we have to a sound-shape pairing the human ear keeps making across cultures it can't share notes with.