The Bouba/Kiki Effect and Wolfgang Köhler

Wolfgang Köhler (1887–1967)

German Gestalt psychologist who discovered the sound-shape mapping phenomenon in 1929 while on Tenerife.

The Original Experiment (1929)

Köhler presented participants with two shapes: one amorphous and curved, the other sharp and jagged. He asked them to assign the invented words “takete” and “maluma” to the shapes. Participants overwhelmingly assigned “maluma” to the rounded shape and “takete” to the jagged, spiky shape.

Evolution into Bouba/Kiki (2001)

Neuroscientists Vilayanur S. Ramachandran and Edward Hubbard adapted Köhler’s experiment during research on synesthesia. They replaced the original words with “Bouba” and “Kiki”, cementing the name used today. When presented with the two shapes, over 95% of people intuitively label the rounded, blob-like shape as Bouba and the sharp, spiky shape as Kiki.

Why It Happens — Sound Symbolism

The phenomenon demonstrates sound symbolism, where the sound of a word physically mirrors its meaning:

• Bouba: The continuous, undulating vocal tract movement of “Bouba” is processed similarly to curved visual edges
• Kiki: The hard, staccato plosive sounds (k, t) mimic sharp angles and sudden direction changes

Universality

The effect has been replicated globally, transcending both language and writing systems. Experiments with infants and toddlers suggest the shape-sound connection is likely hardwired, helping humans learn language by associating abstract vocalizations with physical environments.