Sound symbolism in infancy: Evidence for sound–shape cross-modal correspondences in 4-month-olds

Perceptual experiences in one modality are often dependent on activity from other sensory modalities. These cross-modal correspondences are also evident in language. Adults and toddlers spontaneously and consistently map particular words (e.g., ‘kiki’) to particular shapes (e.g., angular shapes). However, the origins of these systematic mappings are unknown. Because adults and toddlers have had significant experience with the language mappings that exist in their environment, it is unclear whether the pairings are the result of language exposure or the product of an initial proclivity. We examined whether 4-month-old infants make the same sound–shape mappings as adults and toddlers. Four month-olds consistently distinguished between congruent and incongruent sound–shape mappings in a looking time task (Experiment 1). Furthermore, mapping was based on the combination of consonants and vowels in the words given that neither consonants (Experiment 2) nor vowels (Experiment 3) alone sufficed for mapping. Finally, we confirmed that adults also made systematic sound–shape mappings (Experiment 4); however, for adults, vowels or consonants alone sufficed. These results suggest that some sound–shape mappings precede language learning, and may in fact aid in language learning by establishing a basis for matching labels to referents and narrowing the hypothesis space for young infants.