Infants discriminate subtle nasal contrasts late: Evidence from field psycholinguistic experiments on Tagalog-learning infants in the Philippines

Studies suggest that infants initially show universal discrimination abilities. However, this narrative has been heavily based on Indo-European languages. It has also been proposed that infants’ speech sound discrimination is affected by acoustic salience, such that acoustically subtle contrasts are not discriminated until the end of an infant’s first year. Furthermore, others have suggested an influence of word position and positional frequency in discrimination abilities. In Study 1, we analyzed a child-directed corpus of Tagalog, and found that the /n/-/ŋ/ contrast is more frequent in the word-final than -initial position, which might make the contrast easier to discriminate in the final than initial position. In three pre-registered field psycholinguistic studies, we tested the nasal discrimination abilities of Tagalog-learning infants in the Philippines (total n = 60) using a habituation task and the central fixation paradigm. Exp. 1 tested 4- to 6- month-olds’ discrimination of /na/ and /ŋa/, while Exp. 2 tested 10- to 12-month-olds. Exp. 3 tested 4- to 6- month-olds’ discrimination of /an/ and /aŋ/. We found that only the 10- to 12-month-olds showed discrimination of /na/ and /ŋa/. The 4- to 6-month-olds did not show discrimination of the contrast in the word-initial nor in the final position. These results are in line with the acoustic salience account, and with previous findings in studies in Asia showing a late discrimination of native contrasts. We discuss language- and context-specific factors that can explain these results.