Linguistics
Most people, in any language, agree which nonsense word is spiky and which is round
Shown a spiky shape and a rounded blob and asked which is 'bouba' and which is 'kiki,' around 95% of people across many different languages pick the same match — round shape 'bouba,' spiky shape 'kiki.' First observed in the 1920s and renamed and popularised by Ramachandran and Hubbard in 2001, it suggests some sound-to-shape associations may be close to universal rather than arbitrary.