Theories of language acquisition have highlighted the importance of adult speakers as active participants in children’s language learning. However, in many communities children are reported to be directly engaged by their caregivers only rarely (Lieven, 1994). This observation raises the possibility that these children learn language from observing, rather than participating in, communicative exchanges. In this paper, we quantify naturally occurring language input in one community where directed interaction with children has been reported to be rare (Yucatec Mayan). We compare this input to the input heard by children growing up in large families in the United States, and we consider how directed and overheard input relate to Mayan children’s later vocabulary. In Study 1, we demonstrate that 1-year-old Mayan children do indeed hear a smaller proportion of total input in directed speech than children from the US. In Study 2, we show that for Mayan (but not US) children, there are great increases in the proportion of directed input that children receive between 13 and 35 months. In Study 3, we explore the validity of using videotaped data in a Mayan village. In Study 4, we demonstrate that word types directed to Mayan children from adults at 24 months (but not word types overheard by children or word types directed from other children) predict later vocabulary. These findings suggest that adult talk directed to children is important for early word learning, even in communities where much of children’s early language input comes from overheard speech.

The talk children hear from their primary caregivers predicts the size of their vocabularies. But children who spend time with multiple individuals also hear talk that others direct to them, as well as talk not directed to them at all. We investigated the effect of linguistic input on vocabulary acquisition in children who routinely spent time with one vs. multiple individuals. For all children, the number of words primary caregivers directed to them at age 2;6 predicted vocabulary size at age 3;6. For children who spent time with multiple individuals, child-directed words from all household members also predicted later vocabulary and accounted for more variance in vocabulary than words from primary caregivers alone. Interestingly, overheard words added no predictive value to the model. These findings suggest that speech directed to children is important for early word learning, even in households where a sizable proportion of input comes from overheard speech.

How does early social experience affect children's inferences and exploration? Following prior work on children's reasoning in pedagogical contexts, this study examined U.S. children with less experience in formal schooling and Yucatec Mayan children whose early social input is predominantly observational. In Experiment 1, U.S. 2‐year‐olds (n = 77) showed more restricted exploration of a toy following a pedagogical demonstration than an interrupted, accidental, or no demonstration (baseline). In Experiment 2, Yucatec Mayan and U.S. 2‐year‐olds (n = 66) showed more restricted exploration following a pedagogical than an observational demonstration, while only Mayan children showed more restriction with age. These results suggest that although schooling is not a necessary precursor for sensitivity to pedagogy, early social experience may influence children's inferences and exploration in pedagogical contexts.

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Theorists have proposed that child-directed, ostensive interactions provide a critical point of entry for supporting children's learning from others, either because they render the intentions of a teacher easier to understand (e.g., Barresi & Moore, 1996; Moore, 2010; Tomasello, 1999) or because they mark information as culturally important and generalizable (e.g., Csibra & Gergely, 2009). This article evaluates these proposals in light of data from U.S. and European children, as well as from communities where directed interactions with young children are rare. The evidence reviewed from both bodies of work leave reason to doubt the claim that directed interactions provide automatic and innate informational value for learners. Instead, the value of child-directed teaching contexts likely stems from 2 factors: how these interactions focus children's attention in the moment, and how children learn to reason pragmatically regarding the value child-directed contexts have.

In several previous studies, 18-month-old infants who were directly addressed demonstrated more robust imitative behaviors than infants who simply observed another's actions, leading theorists to suggest that child-directed interactions carried unique informational value. However, these data came exclusively from cultural communities where direct teaching is commonplace, raising the possibility that the findings reflect regularities in infants' social experiences rather than responses to innate or a priori learning mechanisms. The current studies consider infants' imitative learning from child-directed teaching and observed interaction in two cultural communities, a Yucatec Mayan village where infants have been described as experiencing relatively limited direct instruction (Study 1) and a US city where infants are regularly directly engaged (Study 2). Eighteen-month-old infants from each community participated in a within-subjects study design where they were directly taught to use novel objects on one day and observed actors using different objects on another day. Mayan infants showed relative increases in imitative behaviors on their second visit to the lab as compared to their first visit, but there was no effect of condition. US infants showed no difference in imitative behavior in the child-directed vs. observed conditions; however, infants who were directly addressed on their first visit showed significantly higher overall imitation rates than infants who observed on their first visit. Together, these findings call into question the idea that child-directed teaching holds automatic or universal informational value.

Child-directed cues support imitation of novel actions at 18 months, but not at two years of age. The current studies explore the mechanisms that underlie the propensity that children have to copy others at 18 months, and how the value of child-directed communication changes over development. We ask if attentional allocation accounts for children's failure to imitate observed actions at 18 months, and their success at two years of age, and we explore the informational value child-directed contexts may provide across ontogeny. Eighteen-month-old (Study 1) and two-year-old (Study 2) children viewed causally non-obvious actions performed by child-directed (Study 1 & 2), observed (Study 1 & 2), or non-interactive (Study 2) actors, and their visual attention and imitative behaviors were assessed. Results demonstrated that child-directed contexts supported imitative learning for 18-month-old children, independent of their effects on proximal attention. However, by two years of age, neither directness nor communication between social partners was a necessary condition for supporting social imitation. These findings suggest that developmental changes in children's propensity to extract information from observation cannot be accounted for by changes in children's interpretation of what counts as child-directed information, and are likely not due to changes in how children allocate attention to observed events.

Like many indigenous populations worldwide, Yucatec Maya communities are rapidly undergoing change as they become more connected with urban centers and access to formal education, wage labour, and market goods became more accessible to their inhabitants. However, little is known about how these changes affect children’s language input. Here, we provide the first systematic assessment of the quantity, type, source, and language of the input received by 29 Yucatec Maya infants born six years apart in communities where increased contact with urban centres has resulted in a greater exposure to the dominant surrounding language, Spanish. Results show that infants from the second cohort received less directed input than infants in the first and, when directly addressed, most of their input was in Spanish. To investigate the mechanisms driving the observed patterns, we interviewed 126 adults from the communities. Against common assumptions, we showed that reductions in Mayan input did not simply result from speakers devaluing the Maya language. Instead, changes in input could be attributed to changes in childcare practices, as well as caregiver ethnotheories regarding the relative acquisition difficulty of each of the languages. Our study highlights the need for understanding the drivers of individual behaviour in the face of socio-demographic and economic changes as it is key for determining the fate of linguistic diversity.