Trilled /r/ is associated with textural roughness in the vocabularies of spoken languages

Roughness is the dominant perceptual dimension of surface touch, and people display strong cross-modal links between rough textures and sound. We show that this tight connection between texture and sound is reflected in the vocabularies of spoken languages. In four studies, we found that words denoting rough textures (e.g. English rough, prickly; Hungarian durva “rough”, szúrós “prickly”) are far more likely to contain the consonant /r/ compared to words for smooth textures (e.g. English smooth, silky; Hungarian sima “smooth”, selymes “silky”). First, we found evidence for this pattern in 1) a large set of English sensory words rated for roughness; 2) a large set of Hungarian sensory words rated for roughness; and 3) a genealogically diverse sample of words for ‘rough’ and ‘smooth’ in 329 languages from 83 phyla. The cross-linguistic evidence allowed us to isolate trilling (intermittent air flow produced by the tongue) as the critical phonetic correlate. Looking more deeply within the Indo-European language family, we found the same pattern in sensory words from a sample of 38 modern Indo-European languages and in reconstructed Proto-Indo-European roots, suggesting temporal stability over thousands of years. Thus, our analyses show that the iconic /r/-roughness pattern is common across spoken languages, extends across multiple sensory words within unrelated languages, and can remain highly stable over time. These results document a new statistical universal connecting form and meaning in spoken vocabularies, one that is rooted in the evolutionarily ancient sense of touch.