An experimental investigation of sound-symbol association in newborn domestic chicks (Gallus gallus)

This paper explores cross-modal correspondence between sound and shape, specifically the Bouba/Kiki phenomenon, in newborn domestic chicks (Gallus gallus). The Bouba/Kiki phenomenon, where a round shape has been shown to be consistently associated with the nonword bouba and a spiky shape with kiki, has been observed in humans across ages and cultures. The study aims to explore the origin of this phenomenon and whether it can be traced to a predisposed mechanism that is possibly shared across humans and domestic chickens. Previous research showed that the effect is present in 3-day old domestic chicks. By using naïve animals, the experiment sought to investigate the Bouba/Kiki effect and sound symbolism in chicks, hypothesizing that the chicks exposed to the “Bouba” sound in ovo would prefer the round shape, and those exposed to the “Kiki” sound would prefer the spiky shape. Contrary to the hypothesis, the results showed a general preference for the round shape in both sound conditions, with no observed preference in the control condition (no exposure to sounds in ovo). Possible explanations are discussed, including the preference for biological objects and face recognition abilities observed in chicks, analogous to the abilities of human infants. Further research is needed to investigate when during development the sound-shape association is expected to develop in chicks and to further explore the origins and functions of sound symbolism across species.