Why do our brains insist on linking the sounds we hear to the sights we see?
In short: We treat sight and sound as our primary senses, yet both are merely narrow, filtered windows onto reality. Despite their physical differences—sound as pressure waves and light as electromagnetic radiation—humans possess an innate, cross-sensory urge to bridge the gap, persistently mapping the visual world onto the sonic one.
The relationship between light and sound has long fascinated thinkers, from Newton’s early attempts to assign musical tones to the colours of the rainbow to Voltaire’s 1738 observation of a secret analogy between the two. While both are wave phenomena, they function as mismatched apertures. Sound unfolds over time, allowing us to parse complex textures like individual notes in a chord. In contrast, light is electromagnetic radiation that arrives as a pre-mixed, spatial experience. Our eyes sample only a tiny sliver of the spectrum, yet we perceive the result as a fused whole, unable to intuitively deconstruct the wavelengths that create a specific hue.
This sensory interplay is deeply rooted in human cognition, often mirroring Plato’s allegory of the cave. Just as the prisoners mistook shadows for reality, our senses provide only fragile reflections of the world. Because our access to reality is constrained by biology and culture, we rely on these narrow windows to construct our experience. This limitation does not make us foolish; it simply defines the boundaries of our perception. We are constantly searching for hidden rapports between these domains, attempting to unify the disparate data provided by our ears and eyes.
Evidence of this cross-sensory mapping appears in how we use language and perceive abstract forms. We often select words for their visual connotation, a phenomenon exemplified by Lewis Carroll’s nonsense words like 'frumious' or 'snickersnack,' which evoke specific imagery despite lacking dictionary definitions. Even more robust is the Bouba-Kiki effect, a century of research showing that humans across cultures consistently associate rounded shapes with soft sounds like 'bouba' and jagged shapes with sharp sounds like 'kiki.' These intuitions may stem from the physical mechanics of speech, such as the rounded mouth shape required to articulate 'bouba,' suggesting that our sensory systems are more interconnected than their distinct biological functions might imply.
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Sources
- Summary by Intellect · source: Music of Light and Colour - Milton Mermikides
- Also: Music of Light and Colour
- Also: podcast.gresham.ac.uk — Music of Light and Colour - Milton Mermikides - Gresham College Lectures
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