I welcome the views of the commentators and am glad that they are likewise enthusiastic about neural network accounts. Nonetheless, I also acknowledge their criticisms, including a lack of attention to processing accounts.

Previous studies of children’s comprehension of the presupposition of English again and its Mandarin equivalent you (requiring that an event of the same kind previously took place) have reported successful acquisition by preschool age. Such studies have generally used tasks that require children to make binary judgments (e.g. “true”/ “false”, “yes”/“no”). However, sentences involving presupposition failure are not necessarily judged as “false” by adults, making such tasks less than optimal for assessing children’s knowledge of presuppositions. In this study, we examine Mandarin-acquiring children’s comprehension of the presupposition of you ‘again’, using two alternative tasks that target the presupposition without requiring participants to make binary judgments about sentences involving presupposition failure. In the Question-Answer Task (Experiment 1), participants listened to stories and answered a wh -question after each story. The results revealed that most children responded as though they ignored the presupposition trigger you , which highlights the methodological challenge of investigating children’s knowledge of presupposition. We then conducted a Felicity Judgment Task (Experiment 2), which highlighted the presence of the trigger by asking participants to decide which of two speakers—one who produced you and one who did not—answered better. In this task, children displayed sensitivity to the presupposition of you , albeit not at adult-like levels. We discuss the implications of these findings in relation to children’s knowledge of you and its obligatory presence when its presupposition is satisfied, a potential ambiguity in its interpretation, and possible differences between children and adults in how they project presuppositions from wh -questions.

Baby sign programs aim to support communication between parents and preverbal infants by pairing signs with spoken words. This study addresses a notable gap in the literature by evaluating the large-scale impact of baby sign on both lexical development and caregiver behavior. Using an online questionnaire in 1348 typically developing, French hearing children (50% female) aged 10 to 28 months, 723 children exposed to baby sign at home were compared with 625 non-exposed peers. After controlling for socioeconomic status and parent–child activities, results revealed weak to no effect of baby sign on vocabulary development or caregiver behavior. These findings suggest that while baby sign is not detrimental to vocabulary development, it does not enhance spoken vocabulary as often claimed.

There is a need for instruments that can assess skills at an early age and that are valid on an international level to support large-scale multicultural research of child development. The Early Communication Indicator (ECI) was developed in the United States to measure expressive communication in the early years, supporting early intervention practitioners and other professionals. It is designed to be applied in any context and in any language, making it applicable internationally. A study involving 480 Portuguese infants and toddlers (aged 6–42 months) that used the ECI provided an opportunity to explore the development of expressive communication using the ECI in a language other than English and in a novel cultural context. The results confirmed a continuum of communication growth and showed similarities with the trajectories found in the U.S. and Australian populations, where the ECI is widely used, for example, to measure communication and monitor intervention in early childhood. Implications for future studies and contributions to theory and practice provided by these new cross-cultural data on ECI are discussed.

In this paper, we present evidence for a root infinitive (RI) stage in Malagasy, an Austronesian language typologically distinct from previously studied RI languages. Drawing on a longitudinal corpus of three Malagasy-speaking children, we show that children frequently produce bare verb forms in root contexts not attested in adult input. These bare forms pattern with null subjects, default pronouns (notably first person izaho instead of aho ), and avoid negation and stative predicates, aligning closely with properties observed with RIs in other languages supporting the existence of an RI analogue in Malagasy. Our findings challenge input-based and constructivist models, which predict that RI forms should be reflected in the input, as Malagasy children’s RI forms emerge despite a near-total absence in caregiver speech. These results reinforce a universalist account of grammatical development and provide new empirical support for syntactic explanations of the RI phenomenon, including use of the aspectual properties of verbs in the temporal anchoring of clauses in child language.

Children and adults use prosocial lies in their everyday conversational exchanges. However, their use of this language form varies across contexts. Extending work demonstrating the importance of conversational partner knowledge for communicative decisions, we examine whether children (ages 8–11 years old; N = 81) and adults’ (N = 218) endorsement of prosocial lies (and truths) differ based on whether a recipient is/is not knowledgeable of the context. Additionally, we examine whether such endorsements varied based on whether the lie (or truth) was about their opinion or the objective reality. Participants were asked to imagine themselves within a scenario with another person who was unaware/aware of a negative event. They then rated how likely they would be to use truth/lie statements which varied in content (i.e., reference to opinion or reality). While children endorsed statements similarly for ignorant/knowledgeable recipients, adults were more likely to endorse telling a prosocial lie when the recipient was ignorant of the negative event. Both groups indicated higher likelihood of telling a prosocial lie about an opinion versus reality. Addressing individual factors, self-reported empathy was not associated with children’s responses but was associated with adults’ communicative choices. Together this work provides information as to how children (and adults) use varying language forms to navigate social situations.

Cross-linguistic research has shown that object which-questions are the hardest types of wh-questions for children to comprehend and are acquired late. The present study asks when Spanish Differential Object Marking (DOM), an early cue to object marking, is actively used to successfully comprehend object which-questions in Spanish-speaking children. We also investigate whether DOM is first used in object which-question with human objects versus animal objects. Fifty-five child learners of Argentinian Spanish ( N = 28, age 5–6; N = 27, age 7–8) and nine monolingual adults participated in a picture matching task. The experimental stimuli are which-questions where DOM indicated an object interpretation ( ¿ A qué bombero object está salpicando la doctora subject ? ) or where absence of DOM made the structure ambiguous between a subject and an object question ( ¿Qué bombero subject/object está salpicando la doctora subject/object ? ). The results showed that DOM helped adults arrive at an object interpretation for object which-questions. When DOM was absent, adult responses did not differ from chance. Children did not use the morphological marking to interpret object which-questions, and absence of DOM determined a strong subject interpretation. In addition, a developmental effect indicates that at age 7 to 8, a subgroup of the children performed target-like. Spanish-speaking children used an agent-first bias to interpret ambiguous which-questions (i.e., without DOM). However, by age 7 to 8, children start using DOM as a reliable cue to override or prevent commitment to an agent-first interpretation.

Despite earlier claims that language abilities are intact in individuals with Williams syndrome (WS), many studies have shown that language development is often delayed and atypical, that is, it develops in line with different cognitive abilities compared to typically developing populations. It is unclear, however, whether general cognitive development predicts language comprehension in WS. The current study is the first to examine the development of grammatical comprehension in a large group ( N = 58) of individuals with WS aged 5 to 21 years old. Grammatical comprehension is key to a person’s ability to understand what is being said and engage in successful social interaction. Using cross-sectional developmental trajectories, performance on the Test for the Reception of Grammar was shown to increase with chronological age and performance was predicted by vocabulary scores, but not non-verbal ability. In addition, there was no meaningful difference between items that contained spatial language and similar grammatical constructions that did not contain spatial language and performance on both types of expressions was similarly predicted by vocabulary scores. Overall, these results show that grammatical development in WS is delayed but not atypical in its relationship to vocabulary.