SRPP: Resolving the bouba-kiki effect enigmas

Mathilde Fort (LPNC, CNRS/UGA)
24 February 2023, 14h0015h30

One central property of natural languages is the arbitrariness of the sign: the sounds of words do not generally inform about their meaning. Still, systematic sound symbolic exceptions to this principle, found in a wide range of languages’ lexicons, have always intrigued scientists and non-scientists. The so-called “bouba-kiki effect” is the textbook case for sensitivity to iconic sound symbolism. When presented with a sound–shape matching task, perceivers almost systematically associate auditory pseudowords such as “bouba” with round or smooth shapes, and others, such as “kiki”, with spiky or angular shapes. Since its first report, the bouba-kiki effect has been robustly replicated across languages, cultures and stimuli, suggesting that it relies on universal cues.
Yet, two intriguing problems remain. First, the stimuli parameters involved in this effect are still unclear. I will first show in a series of experimental studies in adults that both consonants and vowels appear to play a role in the bouba-kiki effect, though consonants to a larger extent. Then, by combining a meta-analysis of independent findings with computational modeling, I will show that this effect mostly relies on two independent non-speech acoustic parameters.
The second issue deals with the underlying mechanisms that could explain such audiovisual associations and whether the bouba-kiki effect is innate or can be learned through exposure to audiovisual regularities in the environment. Indeed, in spite of being very robust in adults and shared by most language and cultures, I will present a series of cross-modal experiments and a second meta-analysis on infants suggesting that this effect is learned. Then, I will present a mathematical demonstration combined with a series of intuitive physics experiments in adults, evidencing the physical principles creating universal audiovisual regularities in the environment and underlying the bouba-kiki effect. Finally, I discuss how this causal mechanistic account provides a complete and coherent resolution of the bouba-kiki effect enigma. I will conclude by raising some new perspectives on how language and human multimodal perception of natural scenes are intrinsically linked.