In all seriousness, and I am surprised the article does not mention this, as dumb as it sounds Kiki has "sharp" sounds when pronouncing it and "Bouba" has a softer feel to it when pronouncing it.
As the article says it does not matter what language you speak, a word that quickly changes the sound back and forth to the same thing sounds sharp because that is how sharp things look and feel. The serration on a knife has the same angle on either side leading to a point. This is what makes sense to me as to why we correspond Kiki to something sharp.
It appears to me that onomatopoeia, at varying degrees, played a role in the spontaneous convergence of verbal communication, and thus the development of a language.
This is just the same thing though?
It's not actually trivially obvious that different minds would agree on how "sharp" and "soft" apply to sounds and to shapes.
Evidence of the bouba-kiki effect in naïve baby chicks - https://news.ycombinator.com/item?id=47105198 - Feb 2026 (107 comments)
Which is "Bouba", and which is "Kiki"? [video] - https://news.ycombinator.com/item?id=46572742 - Jan 2026 (23 comments)
Bouba / Kiki Effect - https://news.ycombinator.com/item?id=45320327 - Sept 2025 (2 comments)
Bouba/kiki effect - https://news.ycombinator.com/item?id=40699583 - June 2024 (170 comments)
Bouba/Kiki Effect - https://news.ycombinator.com/item?id=27885703 - July 2021 (94 comments)
Bouba/kiki effect - https://news.ycombinator.com/item?id=8372550 - Sept 2014 (1 comment)
Why ‘Mom’ and ‘Dad’ Sound So Similar in So Many Languages - https://news.ycombinator.com/item?id=30605239 - March 2022 (1 comment)
Words known better by males than females, and vice versa - https://news.ycombinator.com/item?id=30275159 - Feb 2022 (650 comments)
Why spiky shapes seem angry and round sounds are calming - https://news.ycombinator.com/item?id=20830940 - Aug 2019 (21 comments)
Ability to identify genuine laughter transcends culture - https://news.ycombinator.com/item?id=17634212 - July 2018 (2 comments)
Molyneux's problem - https://news.ycombinator.com/item?id=16778983 - April 2018 (68 comments)
Distant languages have similar sounds for common words - https://news.ycombinator.com/item?id=12510720 - Sept 2016 (60 comments)
Are We All Synesthetes? - https://news.ycombinator.com/item?id=634989 - May 2009 (9 comments)
Oohs And Aahs: Vowel Sounds Affect Our Perceptions Of Products - https://news.ycombinator.com/item?id=54318 - Sept 2007 (4 comments)
I must respectfully disagree; kiki is brown, not red, but it’s an easy mistake to make
I do not think this is realible experiment. Dogs are very sensitive to non verbal cues from their owner.
For example if owner is scared, it will defend the owner. I get assaulted all the time, by dog owners who unleash their dogs on me, in self defense.
It is a bit mysterious why animals would all map e.g. sharp auditory waveforms to sharper / spiky lines (kiki figure), and then smoother sounds to smoother lineforms (bouba figure), but, reasonably, these senses evolved together and used far more shared underlying processing machinery than they do presently. After all, both light and sound reach us in waves and both carry energy.
Some primitive mush-blob perhaps just started processing all incoming energy waves together, differentiating e.g. smoother vs. more staccatto waves before making the distinction between e.g. sound vs. light. Or I dunno, but IMO it makes more sense when you consider evolution, and don't just look at processing now in isolation from the likely development of these senses.
I’ll rush to posit something for others to poke holes in: the definition of a Kiki word is a word where the syllables have a sudden “attack” then decay. And that’s a function of sound, not language.
It would be more interesting if we had two sounds which didn’t have such apparent objective differences giving rise to specific and universal subjective differences, or if something that was not so cross domain elicited a different response, e.g. linking volume with sharpness as opposed to something like size.
Same genetics produce the same outcome (mostly).
DoctorOetker•4d ago
the local curvature is continuous for "Bouba", every point on the curve has a single tangent, which evolves continuously as you walk along this presented curve.
For Kiki: the local curvature is discontinuous: at the inward or outward points, there are 2 tangents, so the tangent abruptly switches value when passing through this point when walking along the curve.
similarly the "B"s in "Bouba" are voiced plosives, while the "K"s in "Kiki" are unvoiced plosives.
I think people would similarily classify "Titi, Pipi, Touta, Poupa, Kouka" like "Kiki" but "Didi, Douda, Bibi, Gigi, Gouga" like "Bouba".
The vowels are obviously voiced by the vocal chord carrier wave "voice".
So when we pass through the unvoiced (T/P/K) plosives, we notice discontinuity like the discontinuously evolving tangents along the boundary curve of the figure.
Obviously mammals like dogs have a concept of continuity, topology, distance, they might get spooked by "open" stairs, because they can see between the planks, etc.
And when we hear voiced (D,B,G) plosives, the voice while muted still evolves continuously.
po1nt•11m ago
notahacker•4m ago