Sound Symbolism in Humans

Is the ability to perceive connections between words that »sound round« and things that »look round« specific to humans? Or can other animals, including our closest living relatives, the great apes, also infer that a meaningless speech sound is ›sharp‹ or ›round‹ and refers to a curved or spiky shape? An international and multidisciplinary team of researchers, including MoA member Friedemann Pulvermüller, has now been able to answer this question using a new experiment with a language-competent bonobo. The results of the collaborative study by multidisciplinary researchers in Europe (Freie Universität Berlin, University of St Andrews, Max Planck Institute for Evolutionary Anthropology) and the United States (Pennsylvania State University, Ape Initiative), led by Konstantina Margiotoudi, was published in the Proceedings of the Royal Society B – Biological Studies on February 2, 2022 and are an important contribution to the field of language emergence in humans, as it suggests that an ability much relevant in shaping »protowords« is plausibly human-specific.

Abstract

Humans share the ability to intuitively map ›sharp‹ or ›round‹ pseudowords, such as ›bouba‹ versus ›kiki‹, to abstract edgy versus round shapes, respectively. This effect, known as sound symbolism, appears early in human development. The phylogenetic origin of this phenomenon, however, is unclear: are humans the only species capable of experiencing correspondences between speech sounds and shapes, or could similar effects be observed in other animals? Thus far, evidence from an implicit matching experiment failed to find evidence of this sound symbolic matching in great apes, suggesting its human uniqueness. However, explicit tests of sound symbolism have never been conducted with nonhuman great apes. In the present study, a language-competent bonobo completed a cross-modal matching-to-sample task in which he was asked to match spoken English words to pictures, as well as ›sharp‹ or ›round‹ pseudowords to shapes. Sound symbolic trials were interspersed among English words. The bonobo matched English words to pictures with high accuracy, but did not show any evidence of spontaneous sound symbolic matching. Our results suggest that speech exposure/comprehension alone cannot explain sound symbolism. This lends plausibility to the hypothesis that biological differences between human and nonhuman primates could account for the putative human specificity of this effect.

Publication

Bo-NO-bouba-kiki: Picture-word mapping but no spontaneous sound symbolic speechshape mapping in a language trained bonobo. Margiotoudi Konstantina, Manuel Bohn, Natalie Schwob, Jared Taglialatela, Friedemann Pulvermüller, Amanda Epping, Ken Schweller and Matthias Allritz. Proceedings of the Royal Society B: Biological Sciences, 2 February 2022.
https://doi.org/10.1098/rspb.2021.1717