Dogs link sharp sounds with angular shapes, study finds

Dogs associate sharper sounds with angular shapes and lower sounds with rounded ones, according to an international study reported by ERR. The finding suggests dogs share with humans a form of sound symbolism, in which sounds are linked to visual shapes.

An Italian-led research team tested 70 adult domestic dogs to see whether they showed the Bouba-Kiki effect: associating the sharp-sounding word “kiki” with a jagged shape and the softer-sounding “bouba” with a rounded one.

In the experiments, dogs saw a round and a jagged shape on two screens while hearing one of the words. In the first round, 51 dogs took part with their owners, who saw and heard the same stimuli. In the second, 19 dogs participated while their owners listened to rock music through headphones, to prevent them from unintentionally influencing the animals.

Researchers used an artificial neural network to track the dogs’ gaze. The dogs looked longer at the round shape when they heard “bouba” and at the jagged shape when they heard “kiki.” They also investigated and sniffed the jagged shape more often and for longer while “kiki” was playing. The sounds did not produce the same clear increase in interest in the round shape.

Team leader Eleonora Biffi said the responses point to cross-sensory perception shared across species. Dogs can also use sound to assess other animals: the pitch of a growl can help them estimate another dog’s size.

The researchers said links between sounds and shapes may help animals interpret their surroundings. Rounded objects bouncing off a surface tend to make lower, smoother sounds, while objects with sharp edges produce shorter, more abrupt sounds, they said. The first experiment also showed that dogs generally preferred jagged shapes regardless of the sound, unlike young children and chicks, which prefer rounded forms. In children, that preference helps them recognise the faces of other people.