Language experienced in utero affects vowel perception after birth: a two-country study

Aims To test the hypothesis that exposure to ambient language in the womb alters phonetic perception shortly after birth. This two‐country study aimed to see whether neonates demonstrated prenatal learning by how they responded to vowels in a category from their native language and another non‐native language, regardless of how much postnatal experience the infants had. Method A counterbalanced experiment was conducted in Sweden (n = 40) and the USA (n = 40) using Swedish and English vowel sounds. The neonates (mean postnatal age = 33 h) controlled audio presentation of either native or non‐native vowels by sucking on a pacifier, with the number of times they sucked their pacifier being used to demonstrate what vowel sounds attracted their attention. The vowels were either the English/i/or Swedish/y/in the form of a prototype plus 16 variants of the prototype. Results The infants in the native and non‐native groups responded differently. As predicted, the infants responded to the unfamiliar non‐native language with higher mean sucks. They also sucked more to the non‐native prototype. Time since birth (range: 7–75 h) did not affect the outcome. Conclusion The ambient language to which foetuses are exposed in the womb starts to affect their perception of their native language at a phonetic level. This can be measured shortly after birth by differences in responding to familiar vs. unfamiliar vowels.