Bouba/kiki effect

The Bouba/Kiki Effect was discovered by German-American psychologist Wolfgang Köhler in 1929. In psychological experiments, first conducted on the island of Tenerife, Köhler showed forms similar to those shown at the right, and found a strong preference to pair the jagged shape with the word "takete" and the rounded shape with the word "baluba" ("maluma" in the 1947 version). In 2001, Vilayanur S. Ramachandran and Edward Hubbard repeated Köhler experiment using the words "kiki" and "bouba" and asked large numbers of subjects "Which of these shapes is bouba and which is kiki?" In tests conducted with both English and Tamil speakers, 95% to 98% picked the curvy shape as bouba and the jagged one as kiki, suggesting that the human brain is somehow able to extract abstract properties from the shapes and sounds. Recent work by Daphne Maurer and colleagues has shown that even children as young as 2.5 (too young to read) show this effect.

Ramachandran and Hubbard suggest that the kiki/bouba effect has implications for the evolution of language, because it suggests that the naming of objects is not completely arbitrary. The rounded shape may most commonly be named bouba because the mouth makes a more rounded shape to produce that sound while a more taut, angular mouth shape is needed to make the sound kiki. The sounds of a K are harder and more forceful than those of a B, as well. The presence of these "synesthesia-like mappings" suggest that this effect might be the neurological basis for sound symbolism, in which sounds are non-arbitrarily mapped to objects and events in the world.

Interestingly, individuals afflicted with autism do not show this effect. Where average people agree with the typical result 90% of the time, autistics only agree 60% of the time.