New research suggests that the bouba-kiki effect is not unique to humans and may originate from ancient neural pathways shared by birds, mammals and even reptilian ancestors.
A new published in Science suggests that the well-known “bouba-kiki effect,” referring to the tendency to associate certain sounds with specific shapes, may be much older than previously thought and is not limited to humans.
The researchers found that newborn chicks display the same sound-shape associations seen in humans, indicating that the phenomenon may have deep roots in vertebrate evolution.
The bouba-kiki effect is a psychological phenomenon in which people consistently associate the nonsense word “bouba” with rounded shapes and “kiki” with pointed and irregular shapes. Experiments in different languages and cultures have repeatedly shown that most humans make the same association, suggesting that the brain naturally links certain sounds to specific visual forms.
The figure on the left is often identified as “kiki” and the one on the right is “bouba”
To test whether this ability extends beyond humans, psychologists at the University of Padua in Italy carried out experiments with newborn chicks.
In the first experiment, three-day-old chicks were placed in an enclosure where the food was hidden behind a panel. After learning to get around the panel to get to the food, the chicks were presented with two options: a panel decorated with a rounded shape and another with a pointed shape, explains .
While the chicks chose between the panels, the researchers played a repetitive sound through speakers — “bouba” or “kiki”. Birds behaved similarly to humans. When the “bouba” sound was played, the puppies tended to approach the rounded shape. When they heard “kiki,” they were more likely to address the pointed shape.
A second experiment with day-old chicks produced similar results. The birds viewed two moving shapes on video screens, one round and the other irregular. Once again, the chicks tended to move toward the shape that corresponded to the sound who heard.
The findings suggest that a brain specifically adapted for human language is not necessary to form these associations. Instead, the capacity can reflect a basic form by which vertebrate brains link information from different senses.
Scientists believe this cross-modal link could help animals integrate audio and visual cues to better understand the environment around them. A commentary accompanying the study argues that the bouba-kiki effect may originate from ancient neural pathways shared by birds, mammals and possibly even their reptilian ancestors.
