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The COVID-19 pandemic massively changed the context and feasibility of developmental research. This new reality, as well as considerations about sample diversity and naturalistic settings for developmental research, highlights the need for solutions for online studies. In this article, we present e-Babylab, an open-source browser-based tool for unmoderated online studies targeted for young children and babies. e-Babylab offers an intuitive graphical user interface for study creation and management of studies, users, participant data, and stimulus material, with no programming skills required. Various kinds of audiovisual media can be presented as stimuli, and possible measures include webcam recordings, audio recordings, key presses, mouse-click/touch coordinates, and reaction times. An additional feature of e-Babylab is the possibility to administer short adaptive versions of MacArthur–Bates Communicative Development Inventories. Information pages, consent forms, and participant forms are customizable. e-Babylab has been used with a variety of measures and paradigms in over 12 studies with children aged 12 months to 8 years (n = 1516). We briefly summarize some results of these studies to demonstrate that data quality, participant engagement, and overall results are comparable between laboratory and online settings. Finally, we discuss helpful tips for using e-Babylab and present plans for upgrades.

Anaphoric pronoun resolution in spoken language has been shown to be influenced by the first mention bias. While this bias has been well investigated in spoken languages, less is known about a similar bias in sign languages. In sign languages, pronominal pointing signs (index) are directed towards referential locations in the signing space typically associated with discourse referents. In German Sign Language (DGS), signers follow an ipsi-contralateral default pattern while tracking referents, i.e., the first referent is associated with the ipsilateral and the second referent with the contralateral area of the signing space. Hence, directing a pronoun to either the ipsi- or the contralateral side of the signing space refers to either the first or the second discourse referent. The present event-related potential study reanalyzes the data fromWienholz et al. (2018) and examines the first mention effect during pronoun resolution in ambiguous contexts in DGS. The original study presented participants with sentence sets containing two referents without overt localization in the first and a sentence-initial pronominal index sign in the second sentence directed to either the ipsilateral or contralateral side of the signing space. Based on the direction of the index sign, our analysis reveals an N400 for contralateral index signs suggesting increased processing costs triggered by a violation of the first mention effect. Thus, the current study provides first experimental evidence for a first mention effect in DGS and highlights the modality-independent nature of this effect.

The COVID-19 pandemic, and the resulting closure of daycare centers worldwide, led to unprecedented changes in children's learning environments. This period of increased time at home with caregivers, with limited access to external sources (e.g., daycares) provides a unique opportunity to examine the associations between the caregiver-child activities and children's language development. The vocabularies of 1742 children aged 8-36 months across 13 countries and 12 languages were evaluated at the beginning and end of the first lockdown period in their respective countries (from March to September 2020). Children who had less passive screen exposure and whose caregivers read more to them showed larger gains in vocabulary development during lockdown, after controlling for SES and other caregiver-child activities. Children also gained more words than expected (based on normative data) during lockdown; either caregivers were more aware of their child's development or vocabulary development benefited from intense caregiver-child interaction during lockdown.

Adult language users can infer the meaning of a previously unfamiliar word from a single exposure to this word in a semantically and thematically constrained context, henceforth, predictive context (Borovsky, Elman, & Kutas, 2012; Borovsky et al., 2010). Children use predictive contexts to anticipate upcoming stimuli (Mani & Huettig, 2012; Borovsky et al., 2012), but the extent to which they rely on prediction to learn novel word forms is unclear (Gambi et al., 2016). Here, we examine children’s one shot learning from predictive contexts using a modified version of the one-shot learning ERP paradigm for children aged 7-13 years. In a first learning phase, we presented audio recordings of expected words and unexpected novel pseudowords in strongly and weakly constraining sentence contexts. In the following priming phase, the same recorded words and pseudowords were used as primes to identical/synonymous, related, and unrelated target words. We measured N400 modulations to the word and pseudoword continuations in the learning phase and to the identical/synonymous, related, or unrelated target words in the priming phase. When initially presented in strongly constraining sentences, novel pseudowords primed synonymous targets equally well as word primes of the same intended meaning. This pattern was particularly pronounced in older children. Our findings suggest that, around early adolescence, children can use single exposures to constraining contexts to infer the meaning of novel words and to integrate these novel words in their lexicons.

Older children with online schooling requirements, unsurprisingly, were reported to have increased screen time during the first COVID-19 lockdown in many countries. Here, we ask whether younger children with no similar online schooling requirements also had increased screen time during lockdown. We examined children’s screen time during the first COVID-19 lockdown in a large cohort (n=2209) of 8-to-36-month-olds sampled from 15 labs across 12 countries. Caregivers reported that toddlers with no online schooling requirements were exposed to more screen time during lockdown than before lockdown. While this was exacerbated for countries with longer lockdowns, there was no evidence that the increase in screen time during lockdown was associated with socio-demographic variables, such as child age and socio-economic status (SES). However, screen time during lockdown was negatively associated with SES and positively associated with child age, caregiver screen time and attitudes towards children’s screen time. The results highlight the impact of the COVID-19 lockdown on young children’s screen time.

Research on the early lexical-semantic system has described how toddlers organize word representations based on semantic and phonological features. This study is a longitudinal investigation of the development of this organization during infancy. Toddlers (n = 28, 15 female) were presented with a preferential looking task using an eye-tracker at 18, 21, and 24 months of age, manipulating semantic and phonological lexical links. Participants were from Mexico, of middle-high socioeconomic status. The experimental task consisted of presenting an auditory label, which was phonologically or semantically related or unrelated, with a displayed target image. Mean proportion of target looking, time-course of fixations, pupillometry, and vocabulary network analysis were used to describe the properties of priming effects. The results showed that phonological priming developed earlier than semantic priming, and that they were produced by behavioral interference. In addition, pupil dilation showed differential use of cognitive effort in critical developmental periods. Finally, the density of vocabulary networks correlated with semantic effects and vocabulary size with phonological effects. These findings extend our understanding of the development of the lexical-semantic system during infancy.

How quickly do children and adults interpret scalar lexical items in speech processing? The current study examined interpretation of the scalar terms some vs. all in contexts where either the stronger (some = not all) or the weaker interpretation was permissible (some allows all). Children and adults showed increased negative deflections in brain activity following the word some in some-infelicitous versus some-felicitous contexts. This effect was found as early as 100 ms across central electrode sites (in children), and 300–500 ms across left frontal, fronto-central, and centro-parietal electrode sites (in children and adults). These results strongly suggest that young children (aged between 3 and 4 years) as well as adults quickly have access to the contextually appropriate interpretation of scalar terms.

One of the most important social cognitive skills in humans is the ability to “put oneself in someone else’s shoes,” that is, to take another person’s perspective. In socially situated communication, perspective taking enables the listener to arrive at a meaningful interpretation of what is said (sentence meaning) and what is meant (speaker’s meaning) by the speaker. To successfully decode the speaker’s meaning, the listener has to take into account which information he/she and the speaker share in their common ground (CG). We here further investigated competing accounts about when and how CG information affects language comprehension by means of reaction time (RT) measures, accuracy data, event-related potentials (ERPs), and eye-tracking. Early integration accounts would predict that CG information is considered immediately and would hence not expect to find costs of CG integration. Late integration accounts would predict a rather late and effortful integration of CG information during the parsing process that might be reflected in integration or updating costs. Other accounts predict the simultaneous integration of privileged ground (PG) and CG perspectives. We used a computerized version of the referential communication game with object triplets of different sizes presented visually in CG or PG. In critical trials (i.e., conflict trials), CG information had to be integrated while privileged information had to be suppressed. Listeners mastered the integration of CG (response accuracy 99.8%). Yet, slower RTs, and enhanced late positivities in the ERPs showed that CG integration had its costs. Moreover, eye-tracking data indicated an early anticipation of referents in CG but an inability to suppress looks to the privileged competitor, resulting in later and longer looks to targets in those trials, in which CG information had to be considered. Our data therefore support accounts that foresee an early anticipation of referents to be in CG but a rather late and effortful integration if conflicting information has to be processed. We show that both perspectives, PG and CG, contribute to socially situated language processing and discuss the data with reference to theoretical accounts and recent findings on the use of CG information for reference resolution.

Developmental research, like many fields, is plagued by low sample sizes and inconclusive findings. The problem is amplified by the difficulties associated with recruiting infant participants for research as well as the increased variability in infant responses. With sequential testing designs providing a viable alternative to paradigms facing such issues, the current study implemented a Sequential Bayes Factor design on three findings in the developmental literature. In particular, using the framework described by Schönbrödt and colleagues (2017), we examined infants’ sensitivity to mispronunciations of familiar words, their learning of novel word-object associations from crosssituational learning paradigms, and their assumption of mutual exclusivity in assigning novel labels to novel objects. We tested an initial sample of 20 participants in  each study, incrementally increasing sample size by one and computing a Bayes Factor with each additional participant. In one study, we were able to obtain moderate evidence for the alternate hypotheses despite testing less than half the number of participants as in the original study. We did not replicate the findings of the cross-situational learning study. Indeed, the data were five times more likely under the null hypothesis, allowing us to conclude that infants did not recognize the trained word-object associations presented in the task. We discuss these findings in light of the advantages and disadvantages of using a Sequential Bayes Factor design in developmental research while also providing researchers with an account of how we implemented this design across multiple studies.

Studies on lexical development in young children often suggest that the organisation of the early lexicon may vary with age and increasing vocabulary size. In the current study, we explicitly examine this suggestion in further detail using a longitudinal study of the development of phonological and semantic priming effects in the same group of toddlers at three different ages. In particular, our longitudinal design allows us to disentangle effects of increasing age and vocabulary size on priming and the extent to which vocabulary size may predict later priming effects. We tested phonological and semantic priming effects in monolingual German infants at 18-, 21- and 24-month-olds. We used the intermodal preferential looking paradigm combined with eye tracking to measure the influence of phonologically and semantic related/unrelated primes on target recognition. We found that phonological priming effects were predicted by participants’ current vocabulary size, even after controlling for participants’ age and participants’ early vocabulary size. Semantic priming effects were, in contrast, not predicted by vocabulary size. Finally, we also found a relationship between early phonological priming effects and later semantic priming effects, as well as between early semantic priming effects and later phonological priming effects, potentially suggesting (limited) consistency in lexical structure across development. Taken together, these results highlight the important role of vocabulary size in the development of priming effects in early childhood.

In recent years, the popularity of tablets has skyrocketed and there has been an explosive growth in apps designed for children. However, many of these apps are released without tests for their effectiveness. This is worrying given that the factors influencing children’s learning from touchscreen devices need to be examined in detail. In particular, it has been suggested that children learn less from passive video viewing relative to equivalent live interaction, which would have implications for learning from such digital tools. However, this so-called video deficit may be reduced by allowing children greater influence over their learning environment. Across two touchscreen-based experiments, we examined whether 2- to 4-year-olds benefit from actively choosing what to learn more about in a digital word learning task. We designed a tablet study in which “active” participants were allowed to choose which objects they were taught the label of, while yoked “passive” participants were presented with the objects chosen by their active peers. We then examined recognition of the learned associations across different tasks. In Experiment 1, children in the passive condition outperformed those in the active condition (n= 130). While Experiment 2 replicated these findings in a new group of Malay-speaking children (n= 32), there were no differences in children’s learning or recognition of the novel word-object associations using a more implicit looking time measure. These results suggest that there may be performance costs associated with active tasks designed as in the current study, and at the very least, there may not always be systematic benefits associated with active learning in touchscreen-based word learning tasks. The current studies add to the evidence that educational apps need to be evaluated before release: While children might benefit from interactive apps under certain conditions, task design and requirements need to consider factors that may detract from successful performance.

From the earliest months of life, infants prefer listening to and learn better from infant-directed speech (IDS) than adult-directed speech (ADS). Yet, IDS differs within communities, across languages, and across cultures, both in form and in prevalence. This large-scale, multi-site study used the diversity of bilingual infant experiences to explore the impact of different types of linguistic experience on infants’ IDS preference. As part of the multi-lab ManyBabies 1 project, we compared lab-matched samples of 333 bilingual and 385 monolingual infants’ preference for North-American English IDS (cf. ManyBabies Consortium, 2020: ManyBabies 1), tested in 17 labs in 7 countries. Those infants were tested in two age groups: 6–9 months (the younger sample) and 12–15 months (the older sample). We found that bilingual and monolingual infants both preferred IDS to ADS, and did not differ in terms of the overall magnitude of this preference. However, amongst bilingual infants who were acquiring North-American English (NAE) as a native language, greater exposure to NAE was associated with a stronger IDS preference, extending the previous finding from ManyBabies 1 that monolinguals learning NAE as a native language showed a stronger preference than infants unexposed to NAE. Together, our findings indicate that IDS preference likely makes a similar contribution to monolingual and bilingual development, and that infants are exquisitely sensitive to the nature and frequency of different types of language input in their early environments.

A number of studies provide evidence for a phonological priming effect in the recognition of single signs based on phonological parameters and that the specific phonological parameters modulated in the priming effect can influence the robustness of this effect. This eye tracking study on German Sign Language examined phonological priming effects at the sentence level, while varying the phonological relationship between prime-target sign pairs. We recorded participants’ eye movements while presenting videos of sentences containing either related or unrelated prime-target sign pairs, and pictures of the target and an unrelated distractor. We observed a phonological priming effect for sign pairs sharing handshape and movement while differing in location parameter. Taken together, the data suggest a difference in the contribution of sign parameters to sign recognition and that sub-lexical features influence sign language processing.

Since signs and words are perceived and produced in distinct sensory-motor systems, they do not share a phonological basis. Nevertheless, many deaf bilinguals master a spoken language with input merely based on visual cues like mouth representations of spoken words and orthographic representations of written words. Recent findings further suggest that processing of words involves cross-language cross-modal co-activation of signs in deaf and hearing bilinguals. Extending these findings in the present ERP-study, we recorded the electroencephalogram (EEG) of fifteen congenitally deaf bilinguals of German Sign Language (DGS) (native L1) and German (early L2) as they saw videos of semantically and grammatically acceptable sentences in DGS. Within these DGS-sentences, two signs functioned as prime and target. Prime and target signs either had an overt phonological overlap as signs (phonological priming in DGS), or were phonologically unrelated as signs but had a covert orthographic overlap in their written German translation (orthographic priming in German). Results showed a significant priming effect for both conditions. Target signs that were either phonologically related as signs or had an underlying orthographic overlap in their written German translation engendered a less negative going polarity in the electrophysiological signal compared to overall unrelated control targets. We thus provide first evidence that deaf bilinguals co-activate their secondly acquired ‘spoken/written’ language German during whole sentence processing of their native sign language DGS.

Caregivers typically use an exaggerated speech register known as infant-directed speech (IDS) in communication with infants. Infants prefer IDS over adult-directed speech (ADS) and IDS is functionally relevant in infant-directed communication. We examined interactions between maternal IDS quality, infants’ preference for IDS over ADS, and the functional relevance of IDS at 6- and 13-months. While 6-month-olds showed a preference for IDS over ADS, 13-month-olds did not. Differences in gaze following behavior triggered by speech register (IDS vs. ADS) were found in both age groups. The degree of infants’ preference for IDS (relative to ADS) was linked to the quality of maternal IDS infants were exposed to. No such relationship was found between gaze following behavior and maternal IDS quality and infant IDS preference. The results speaks to a dynamic interaction between infants’ preference for different kinds of social signals and the social cues available to them. 

Preschoolers learn selectively from others based on the speakers' prior accuracy. This indicates that they recognize the models' (in)competence and use it to predict who will provide the most accurate and useful information in the future. Here, we investigated whether 5-y.-o. children are also able to use speaker reliability retrospectively, once they have more information regarding their competence. They first experienced two previously unknown speakers who provided conflicting information about the referent of a novel label, with each speaker using the same novel label to refer exclusively to a different novel object. Following this, children learned about the speakers' differing labeling accuracy. Subsequently, children selectively endorsed the object-label link initially provided by the speaker who turned out to be reliable significantly above chance. Crucially, more than half of these children justified their object selection with reference to speaker reliability, indicating the ability to explicitly reason about their selective trust in others based on the informants' individual competences. Findings further corroborate the notion that preschoolers are able to use advanced, metacognitive strategies (trait reasoning) to learn selectively. In contrast, since learning preceded reliability exposure and gaze data showed no preferential looking toward the more reliable speaker, findings cannot be accounted for by attentional bias accounts of selective social learning.