Beyond bouba/kiki: Multidimensional semantic signals are deeply woven into the fabric of natural language

TL;DR

This study reveals that individual phonemes in English encode structured, multidimensional semantic signals, challenging the idea that sound-meaning relationships are arbitrary, and shows these mappings are consistent across languages and detectable by language models.

Contribution

The paper demonstrates that phonemes carry systematic semantic signals across multiple dimensions, supported by model recovery, behavioral validation, and cross-linguistic evidence.

Findings

Large language models recover consistent phoneme-meaning associations.

Behavioral data confirms phoneme-semantic mappings at 80.8% accuracy.

Core phoneme-meaning mappings generalize across diverse languages.

Abstract

A foundational assumption in linguistics holds that the relationship between a word's sound and its meaning is arbitrary. Accumulating evidence from sound symbolism challenges this view, yet no study has systematically mapped the multidimensional semantic profile of every phonological unit within a language. Here we show that individual letter-phonemes in English carry structured, multidimensional semantic signals. Using a minimal-pair paradigm spanning all 220 pairwise letter contrasts, three large language models independently recover consistent phoneme-meaning associations across nine perceptual dimensions. These associations are systematically predicted by articulatory-phonetic features, with manner and place of articulation mapping onto distinct semantic dimensions. Behavioral data from English speakers confirm these patterns at rates well above chance (80.8%), and preliminary cross-linguistic evidence from five typologically diverse languages suggests that core mappings generalize beyond English. Our findings indicate that sound-meaning iconicity is not an occasional curiosity but a pervasive, structured property of the phonological signal, one so systematic that large language models recover it when given only text input, without exposure to speech or articulation during the task.