We found a non-obvious pathway to robust language learnability across cultures & languages. Future work will assess just how widespread this pathway is across the world’s languages, and the role that contingent simplification plays in language development. 9/9

Languages don't only become learnable over evolution, they’re also learnable at precise moments during language development. Children actively shape their own learning input, eliciting learnable speech during vocal turn-taking, the central context of language use. 8/9

Languages must be learnable by the next generation, otherwise they would not exist. Here we show the simplification effect is robust across languages, contexts, and types of social interaction. Contingent simplified speech may be a cross-linguistic key to language learnability. 7/9

What this cross-cultural robustness implies is that the simplification effect of contingent speech is likely to be present in many more language than the 13 we studied in this paper. 6/9

A language we studied in this paper—Tseltal Mayan—was a particularly useful test case because Tseltal caregivers don’t use exaggerated child-directed speech typically found in industrialized societies. Despite this, we found a robust simplification in Tseltal caregiver speech. 5/9

Only parental speech that was contingent (produced immediately following their children’s vocalizations) was simplified, even though both contingent and non-contingent speech were similar in child-directed exaggerated pitch. 4/9

In response to their child’s immature speech, caregivers produce fewer unique words, shorter utterances and more single-word utterances compared to caregivers’ baseline speech complexity. We call this the simplification effect of contingent speech. 3/9

w/ @mikehgoldstein.bsky.social & Jacob Levy we show that children’s immature vocalizations & speech actively elicit language from caregivers that is linguistically simplified & more learnable. We find this in 13 languages, showing a robust social pathway for making language learning easier to do 2/9

We found a non-obvious pathway to robust language learnability across cultures & languages. Future work will assess just how widespread this pathway is across the world’s languages, and the role that contingent simplification plays in language development. 9/9

Languages don't only become learnable over evolution, they’re also learnable at precise moments during language development. Children actively shape their own learning input, eliciting learnable speech during vocal turn-taking, the central context of language use. 8/9

Languages must be learnable by the next generation, otherwise they would not exist. Here we show the simplification effect is robust across languages, contexts, and types of social interaction. Contingent simplified speech may be a cross-linguistic key to language learnability. 7/9

What this cross-cultural robustness implies is that the simplification effect of contingent speech is likely to be present in many more language than the 13 we studied in this paper. 6/9

A language we studied in this paper—Tseltal Mayan—was a particularly useful test case because Tseltal caregivers don’t use exaggerated child-directed speech typically found in industrialized societies. Despite this, we found a robust simplification in Tseltal caregiver speech. 5/9

Only parental speech that was contingent (produced immediately following their children’s vocalizations) was simplified, even though both contingent and non-contingent speech were similar in child-directed exaggerated pitch. 4/9

In response to their child’s immature speech, caregivers produce fewer unique words, shorter utterances and more single-word utterances compared to caregivers’ baseline speech complexity. We call this the simplification effect of contingent speech. 3/9

w/ @mikehgoldstein.bsky.social & Jacob Levy we show that children’s immature vocalizations & speech actively elicit language from caregivers that is linguistically simplified & more learnable. We find this in 13 languages, showing a robust social pathway for making language learning easier to do 2/9