The cerebral bases of the bouba-kiki effect

Nathan Peiffer-Smadja,Laurent Cohen

doi:10.1016/j.neuroimage.2018.11.033

Abstract

The crossmodal correspondence between some speech sounds and some geometrical shapes, known as the bouba-kiki (BK) effect, constitutes a remarkable exception to the general arbitrariness of the links between word meaning and word sounds. We have analyzed the association of shapes and sounds in order to determine whether it occurs at a perceptual or at a decisional level, and whether it takes place in sensory cortices or in supramodal regions. First, using an Implicit Association Test (IAT), we have shown that the BK effect may occur without participants making any explicit decision relative to sound-shape associations. Second, looking for the brain correlates of implicit BK matching, we have found that intermodal matching influences activations in both auditory and visual sensory cortices. Moreover, we found stronger prefrontal activation to mismatching than to matching stimuli, presumably reflecting a modulation of executive processes by crossmodal correspondence. Thus, through its roots in the physiology of object categorization and crossmodal matching, the BK effect provides a unique insight into some non-linguistic components of word formation.

Highlights

IntroductionIn 1929, Wolfgang Ko€hler showed participants two novel shapes, one roundish and one spiky, and proposed the two pseudowords “baluma” (changed into “maluma” in later studies) and “takete” (Ko€hler, 1929, 1947)
In 1929, Wolfgang Ko€hler showed participants two novel shapes, one roundish and one spiky, and proposed the two pseudowords “baluma” and “takete” (Ko€hler, 1929, 1947)
We study whether the bouba-kiki effect (BK) effect still prevails with an implicit task derived from the Implicit Association Test (IAT) paradigm (Greenwald et al, 1998), as first assessed by Parise and Spence (2012) and Lacey et al (2016), a task in which participants do not respond based on their introspection, and are not informed that the topic of the study is crossmodal matching

Summary

Introduction

In 1929, Wolfgang Ko€hler showed participants two novel shapes, one roundish and one spiky, and proposed the two pseudowords “baluma” (changed into “maluma” in later studies) and “takete” (Ko€hler, 1929, 1947). Ko€hler (1947) observed that “most people answered without any hesitation”, choosing “b/maluma” for the round shape and “takete” for the spiky shape. This simple experiment brought to light a strong and consensual link (Chen et al, 2018) between meaningless speech sounds and geometrical shapes, an effect often referred to as the bouba-kiki effect (BK; Ramachandran and Hubbard, 2001). The BK effect is one among a multitude of crossmodal correspondences (for a review, see Spence, 2011), including links between different modalities or conceptual fields, such as for instance “down” being associated with darkness, small numbers, low-pitch sounds, sadness, as opposed to “up” being associated with light, large numbers, high-pitch sounds, joy, etc. The links between synaesthesia and mere correspondences remain a controversial issue (Deroy and Spence, 2013)

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Conclusion