A freshly emerged chick, merely hours old and unsteady on its legs, stands in a compact arena. In front of it, a screen shows two forms: one with smooth, rounded contours and another with sharp, jagged lines. From a concealed speaker, a nonsensical term, “bouba,” is played on repeat. The chick approaches the rounded form, spending more than three minutes examining it. When the term “kiki” is instead played, other chicks dart directly towards the spiky form.
This experiment illustrates the bouba-kiki effect, a phenomenon long considered exclusive to humans. Across different cultures, individuals associate the word “bouba” with smooth, rounded shapes and “kiki” with jagged, pointed ones, hinting at a potential insight into the roots of language.
Nonetheless, chickens do not possess language abilities and cannot vocalize the terms themselves. Yet a research study by Maria Loconsole and her colleagues at the University of Padova demonstrates that newly hatched chicks show the same sound-shape connections within their first day of existence. This contradicts the notion that the bouba-kiki effect serves as a precursor to human language, suggesting it is a much older and fundamental cognitive ability.
In the study, 42 chicks aged three days were trained to navigate around a shape that combined both rounded and jagged edges to receive food. Later, when confronted with two panels, one round and one sharp, while hearing either “bouba” or “kiki,” the chicks consistently selected the round panel for “bouba” and the spiky one for “kiki.” Another experiment involving 40 chicks, tested within 24 hours of hatching without any prior training, demonstrated comparable outcomes.
These results indicate an inherent perceptual bias, with chicks’ brains appearing prewired to correlate certain sounds with specific shapes. Aleksandra Ćwiek, a linguist, refers to this finding as significant, suggesting that such sound-shape connections exist before language and point to a larger cognitive capability to link sensory information.
Chimpanzees, gorillas, and the bonobo Kanzi have previously failed similar bouba-kiki assessments, leading researchers to think the effect was specific to humans. However, it is contended that extensive prior training may have affected these results.
The roots of the bouba-kiki effect might be found in the physical environment: round objects emit low-frequency sounds, while angular ones generate sharper tones. This ability to synchronize visual and auditory signals could assist a newborn animal in swiftly navigating its surroundings for survival, implying the effect relates more to survival instincts than to language.
For further exploration, the complete study can be accessed at [Science](https://www.science.org/doi/10.1126/science.adq7188).