Bouba
Two shapes, two made-up words. Pick which one is 'bouba', then see how astonishingly little you were choosing at random.
One of these made-up words is “bouba”, the other is “kiki”. Don't overthink it, which shape is bouba?
Almost nobody truly picks at random. About 95% of people tie the round blob to “bouba” and the spiky one to “kiki”. Wolfgang Köhler first spotted it in 1929, and a 2022 study found the effect in 17 of 25 languages. Say them: your lips round out for the soft “b” and “ooo”, then pull tight and sharp for the hard “k” and “i”. The sound of the word feels like the shape.
Our sources
// every fact this game reveals was checked before it went up
✓ Shown a round shape and a spiky shape, the large majority of people (a classic figure of ~95%) match the round one to 'bouba' and the spiky one to 'kiki'; the effect was first shown by Wolfgang Köhler in 1929.
, Ramachandran & Hubbard, 'Synaesthesia. A Window Into Perception, Thought and Language,' 2001; Köhler, Gestalt Psychology, 1929
✓ The bouba/kiki effect holds across most but not all cultures: a 2022 study of about 900 speakers across 25 languages found it in 17 of them, robust across different writing systems.
, Ćwiek et al., 'The bouba/kiki effect is robust across cultures and writing systems,' Philosophical Transactions of the Royal Society B, 2022
≈ A leading explanation links the sound to the mouth's shape while saying it: rounded lips and voiced 'b' for 'bouba' echo a round form, while the tight, sharp articulation of 'kiki' echoes a jagged one, a cross-sensory (sound-to-shape) mapping.
, Ramachandran & Hubbard, 2001; sound-symbolism research