Infant-directed input and literacy effects on phonological processing: Non-word repetition scores among the Tsimane'.

Language input in childhood and literacy (and/or schooling) have been described as two key experiences impacting phonological processing. In this study, we assess phonological processing via a non-word repetition (NWR) group game, in adults and children living in two villages of an ethnic group where infants are rarely spoken to, and where literacy is variable. We found lower NWR scores than in previous work for both children (N = 17; aged 1-12 years) and adults (N = 13; aged 18-60 years), which is consistent with the hypothesis that there would be long-term effects on phonological processing of experiencing low levels of directed input in infancy. Additionally, we found some evidence that literacy and/or schooling increases NWR scores, although results should be interpreted with caution given the small sample size. These findings invite further investigations in similar communities, as current results are most compatible with phonological processing being influenced by aspects of language experience that vary greatly between and within populations.