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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.

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.

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.

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.

Several studies have shown that unbalanced bilinguals activate both of their languages simultaneously during L2 processing; however, evidence for L2 activation while participants are tested exclusively in their L1 has been more tenuous. Here, we investigate whether bilingual participants implicitly activate the label for a picture in their two languages, and whether labels activated in L2 can prime activation of cross-linguistically related L1 lexical targets. We tested highly proficient early Spanish-Basque bilinguals on an ERP cross-modal priming task conducted only in their L1, Spanish. Participants activated prime picture labels in both Spanish and Basque. More importantly, participants activated Basque translations of Spanish auditory targets, even in a Spanish experimental environment with no reference to Basque. Results provide strong evidence for non-selective bilingual lexical access, showing co-activation extending to lexical levels beyond phonological overlap. Our results add to the growing body of evidence for the interconnective nature of bilingual language activation.

The field of psychology has become increasingly concerned with issues related to methodology and replicability. Infancy researchers face specific challenges related to replicability: high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations, amongst other factors. Addressing these concerns, we report on a large-scale, multi-site study aimed at 1) assessing the overall replicability of a single theoretically-important phenomenon and 2) examining methodological, situational, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult were created using semi-naturalistic laboratory-based audio recordings in North American English. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three commonly-used infant discrimination methods (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35 [0.29 - 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together these findings replicate the infant-directed speech preference but suggest that its magnitude is modulated by development, native language experience, and testing procedure.

The overall pattern of vocabulary development is relatively similar across children learning different languages. However, there are considerable differences in the words known to individual children. Historically, this variability has been explained in terms of differences in the input. Here, we examine the alternate possibility that children’s individual interest in specific natural categories shapes the words they are likely to learn – a child who is more interested in animals will learn a new animal name easier relative to a new vehicle name. Two-year-old German-learning children (N=39) were exposed to four novel word-object associations for objects from four different categories. Prior to the word learning task, we measured their interest in the categories that the objects belonged to. Our measure was pupillary change following exposure to familiar objects from these four categories, with increased pupillary change interpreted as increased interest in that category. Children showed more robust learning of word-object associations from categories they were more interested in relative to categories they were less interested in. We further found that interest in the novel objects themselves influenced learning, with distinct influences of both category interest and object interest on learning. These results suggest that children’s interest in different natural categories shapes their word learning. This provides evidence for the strikingly intuitive possibility that a child who is more interested in animals will learn novel animal names easier than a child who is more interested in vehicles.

In this series of experiments, we tested the limits of young infants’ word learning and generalization abilities in light of recent findings reporting sophisticated word learning abilities in the first year of life. Ten-month-old infants were trained with two word-object pairs and tested with either the same or different members of the corresponding categories. In Experiment 1, infants showed successful learning of the word-object associations, when trained and tested with a single exemplar from each category. In Experiment 2, infants were presented with multiple within-category items during training but failed to learn the word-object associations. In Experiment 3, infants were presented with a single exemplar from each category during training, and failed to generalize labels to a new category exemplar. However, when infants were trained with items from perceptually and conceptually distinct categories in Experiment 4, they showed weak evidence for generalization of labels to novel members of the corresponding categories. It is suggested that word learning in the first year begins as the formation of simple associations between words and objects that become enriched as experience with objects, words and categories accumulates across development. 

Successful communication often involves comprehension of both spoken language and observed actions with and without objects. Even very young infants can learn associations between actions and objects as well as between words and objects. However, in daily life, children are usually confronted with both kinds of input simultaneously. Choosing the critical information to attend to in such situations might help children structure the input, and thereby, allow for successful learning. In the current study, we therefore, investigated the developmental time course of children’s and adults’ word and action learning when given the opportunity to learn both word-object and action-object associations for the same object. All participants went through a learning phase and a test phase. In the learning phase, they were presented with two novel objects which were associated with a distinct novel name (e.g., ”Look, a Tanu”) and a distinct novel action (e.g., moving up and down while tilting sideways). In the test phase, participants were presented with both objects on screen in a baseline phase, then either heard one of the two labels or saw one of the two actions in a prime phase, and then saw the two objects again on screen in a recognition phase. Throughout the trial, participants’ target looking was recorded to investigate whether participants looked at the target object upon hearing its label or seeing its action, and thus, would show learning of the word-object and action-object associations. Growth curve analyses revealed that 12-month-olds showed modest learning of action-object associations, 36-month-olds learned word-object associations, and adults learned word-object and action-object associations. These results highlight how children attend to the different information types from the two modalities through which communication is addressed to them. Over time, with increased exposure to systematic word-object mappings, children attend less to action-object mappings, with the latter potentially being mediated by word-object learning even in adulthood. Thus, choosing between different kinds of input that may be more relevant in their rich environment encompassing different modalities might help learning at different points in development.

Communication with young children is often multimodal in nature, involving, for example, language and actions. The simultaneous presentation of information from both domains may boost language learning by highlighting the connection between an object and a word, owing to temporal overlap in the presentation of multimodal input. However, the overlap is not merely temporal but can also co-vary in the extent to which particular actions co-occur with particular words and objects, e.g., caregivers typically produce a hopping action when talking about rabbits and a snapping action for crocodiles. The frequency with which actions and words co-occur in the presence of the referents of these words may also impact young children's word learning. We therefore examined the extent to which consistency in the co-occurrence of particular actions and words impacted children's learning of novel word-object associations. Children (18 months, 30 months, 36 - 48 months) and adults were presented with two novel objects and heard their novel labels while different actions were performed on these objects, such that the particular actions and word-object pairings always co-occurred (Consistent group) or varied across trials (Inconsistent group). At test, participants saw both objects and heard one of the labels to examine whether participants recognised the target object upon hearing its label. Growth curve models revealed that 18-month-olds did not learn words for objects in either condition, and 30-month-old and 36- to 48-month-old children learned words for objects only in the Consistent condition, in contrast to adults who learned words for objects independent of the actions presented. Thus, consistency in the multimodal input influenced word learning in early childhood but not in adulthood. In terms of a dynamic systems account of word learning, our study shows how multimodal learning settings interact with the child's perceptual abilities to shape the learning experience.

The MacArthur-Bates Communicative Development Inventories (CDIs) are among the most widely used evaluation tools for early language development. CDIs are filled in by the parents or caregivers of young children by indicating which of a prespecified list of words and/or sentences their child understands and/or produces. Despite the success of these instruments, their administration is time-consuming and can be of limited use in clinical settings, multilingual environments, or when parents possess low literacy skills. We present a new method through which an estimation of the full-CDI score can be obtained, by combining parental responses on a limited set of words sampled randomly from the full CDI with vocabulary information extracted from the WordBank database, sampled from age-, gender-, and language-matched participants. Real-data simulations using versions of the CDI-WS for American English, German, and Norwegian as examples revealed the high validity and reliability of the instrument, even for tests having just 25 words, effectively cutting administration time to a couple of minutes. Empirical validations with new German-speaking participants confirmed the robustness of the test.

Sign languages use the horizontal plane to refer to discourse referents introduced at referential locations. However, the question remains whether the assignment of discourse referents follows a particular default pattern as recently proposed such that two new discourse referents are respectively assigned to the right (ipsilateral) and left (contralateral) side of (right handed) signers. The present event-related potential study on German Sign Language investigates the hypothesis that signers assign distinct and contrastive referential locations to discourse referents even in the absence of overt localization. By using a semantic mismatch-design, we constructed sentence sets where the second sentence was either consistent or inconsistent with the used pronoun. Semantic mismatch conditions evoked an N400, whereas a contralateral  index  sign engendered a Phonological Mismatch Negativity. The current study provides supporting evidence that signers are sensitive to the mismatch and make use of a default pattern to assign distinct and contrastive referential locations to discourse referents.

Purpose of Review To summarize findings about the emergence and characteristics of canonical babbling in children with late detected developmental disorders (LDDDs), such as autism spectrum disorder, Rett syndrome, and fragile X syndrome. In particular, we ask whether infants’ vocal development in the first year of life contains any markers that may contribute to earlier detection of these disorders. Recent Findings Only a handful studies have investigated canonical babbling in infants with LDDDs. With divergent research paradigms and definitions applied, findings on the onset and characteristics of canonical babbling are inconsistent and difficult to compare. Infants with LDDDs showed reduced likelihood to produce canonical babbling vocalizations. If achieved, this milestone was more likely to be reached beyond the critical time window of 5–10 months. Summary Canonical babbling appears promising as a potential marker for early detection of infants at risk for developmental disorders. In-depth studies on babbling characteristics in LDDDs are warranted.