Exploration of factors affecting webcam-based automated gaze coding.

Online experiments have been transforming the field of behavioral research, enabling researchers to increase sample sizes, access diverse populations, lower the costs of data collection, and promote reproducibility. The field of developmental psychology increasingly exploits such online testing approaches. Since infants cannot give explicit behavioral responses, one key outcome measure is infants' gaze behavior. In the absence of automated eyetrackers in participants' homes, automatic gaze classification from webcam data would make it possible to avoid painstaking manual coding. However, the lack of a controlled experimental environment may lead to various noise factors impeding automatic face detection or gaze classification. We created an adult webcam dataset that systematically reproduced noise factors from infant webcam studies which might affect automated gaze coding accuracy. We varied participants' left-right offset, distance to the camera, facial rotation, and the direction of the lighting source. Running two state-of-the-art classification algorithms (iCatcher+ and OWLET) revealed that facial detection performance was particularly affected by the lighting source, while gaze coding accuracy was consistently affected by the distance to the camera and lighting source. Morphing participants' faces to be unidentifiable did not generally affect the results, suggesting facial anonymization could be used when making online video data publicly available, for purposes of further study and transparency. Our findings will guide improving study design for infant and adult participants during online experiments. Moreover, training algorithms using our dataset will allow researchers to improve robustness and allow developmental psychologists to leverage online testing more efficiently.

Infants' use of the index finger for social and non-social purposes during the first two years of life: A cross-cultural study.

The emergence of the pointing gesture is a major developmental milestone in human infancy. Pointing fosters preverbal communication and is key for language and theory of mind development. Little is known about its ontogenetic origins and whether its pathway is similar across different cultures. The goal of this study was to examine the theoretical proposal that social pointing is preceded by a non-social use of the index finger and later becomes a social-communicative gesture. Moreover, the study investigated to which extent the emergence of social pointing differs cross-culturally. We assessed non-social index-finger use and social pointing in 647 infants aged 3- to 24 months from 4 different countries (China, Germany, Japan, and Türkiye). Non-social index-finger use and social pointing increased with infants' age, such that social pointing became more dominant than non-social index-finger use with age. Whereas social pointing was reported across countries, its reported frequency differed between cultures with significantly greater social pointing frequency in infants from Türkiye, China, and Germany compared to Japanese infants. Our study supports theoretical proposals of the dominance of non-social index-finger use during early infancy with social pointing becoming more prominent as infants get older. These findings contribute to our understanding of infants' use of their index finger for social and non-social purposes during the first two years of life.

Infants' preference for speech is stable across the first year of life: Meta-analytic evidence.

Previous work suggested that humans' sophisticated speech perception abilities stem from an early capacity to pay attention to speech in the auditory environment. What are the roots of this early preference? We assess the extent to which it is due to it being a vocal sound, a natural sound, and a familiar sound through a meta-analytic approach, classifying experiments as a function of whether they used native or foreign speech and whether the competitor, against which preference is tested, was vocal or non-vocal, natural or artificial. We also tested for the effect of age. Synthesizing data from 791 infants across 39 experiments, we found a medium effect size, confirming at the scale of the literature that infants reliably prefer speech over other sounds. This preference was not significantly moderated by the language used, vocal quality, or naturalness of the competitor, nor by infant age. The current body of evidence appears most compatible with the hypothesis that speech is preferred consistently as such and not just due to its vocal, natural, or familiar nature. We discuss limitations of the extant body of work on speech preference, including evidence consistent with a publication bias and low representation of certain stimuli types and ages.

Mask wearing in Japanese and French nursery schools: The perceived impact of masks on communication.

Due to the global COVID-19 pandemic, covering the mouth region with a face mask became pervasive in many regions of the world, potentially impacting how people communicate with and around children. To explore the characteristics of this masked communication, we asked nursery school educators, who have been at the forefront of daily masked interaction with children, about their perception of daily communicative interactions while wearing a mask in an online survey. We collected data from French and Japanese nursery school educators to gain an understanding of commonalities and differences in communicative behavior with face masks given documented cultural differences in pre-pandemic mask wearing habits, face scanning patterns, and communicative behavior. Participants (177 French and 138 Japanese educators) reported a perceived change in their own communicative behavior while wearing a mask, with decreases in language quantity and increases in language quality and non-verbal cues. Comparable changes in their team members' and children's communicative behaviors were also reported. Moreover, our results suggest that these changes in educators' communicative behaviors are linked to their attitudes toward mask wearing and their potential difficulty in communicating following its use. These findings shed light on the impact of pandemic-induced mask wearing on children's daily communicative environment.

Quantifying developmental and individual differences in spontaneous drawing completion among children.

This study investigated how children's drawings can provide insights into their cognitive development. It can be challenging to quantify the diversity of children's drawings across their developmental stages as well as between individuals. This study observed children's representational drawing ability by conducting a completion task where children could freely draw on partially drawn objects, and quantitatively analyzed differences in children's drawing tendencies across age and between individuals. First, we conducted preregistered analyses, based on crowd-sourced adult ratings, to investigate the differences of drawing style with the age and autistic traits of the children, where the latter was inspired by reports of atypical drawing among children with autism spectrum disorder (ASD). Additionally, the drawings were quantified using feature representations extracted with a deep convolutional neural network (CNN), which allowed an analysis of the drawings at different perceptual levels (i.e., local or global). Findings revealed a decrease in scribbling and an increase in completion behavior with increasing age. However, no correlation between drawing behavior and autistic traits was found. The network analysis demonstrated that older children adapted to the presented stimuli in a more adult-like manner than younger children. Furthermore, ways to quantify individual differences in how children adapt to the presented stimuli are explored. Based on the predictive coding theory as a unified theory of how perception and behavior might emerge from integrating sensations and predictions, we suggest that our analyses may open up new possibilities for investigating children's cognitive development.

The effect of older sibling, postnatal maternal stress, and household factors on language development in two- to four-year-old children.

Previous literature has shown that family structure affects language development. Here, factors relating to older siblings (their presence in the house, sex, and age gap), mothers (maternal stress), and household size and residential crowding were assessed to systematically examine the different roles of these factors. Data from mother-child dyads in a Singaporean birth cohort, (677-855 dyads; 52% males; 58% to 61% Chinese, 20% to 24% Malay, 17% to 19% Indian) collected when children were 24, 48, and 54 months old, were analyzed. There was a negative effect of having an older sibling, moderated by the siblings' age gap, but not by the older sibling's sex, nor household size or residential crowding. Maternal stress affected language outcomes in some analyses but not others. Implications for understanding the possible effects of family structure on language development are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Simulating Developmental and Individual Differences of Drawing Behavior in Children Using a Predictive Coding Model.

Predictive coding has recently been proposed as a mechanistic approach to explain human perception and behavior based on the integration of perceptual stimuli (bottom-up information) and the predictions about the world based on previous experience (top-down information). However, the gap between the computational accounts of cognition and evidence of behavioral studies remains large. In this study, we used a computational model of drawing based on the mechanisms of predictive coding to systematically investigate the effects of the precision of top-down and bottom-up information when performing a drawing completion task. The results indicated that sufficient precision of both signals was required for the successful completion of the stimuli and that a reduced precision in either sensory or prediction (i.e., prior) information led to different types of atypical drawing behavior. We compared the drawings produced by our model to a dataset of drawings created by children aged between 2 and 8 years old who drew on incomplete drawings. This comparison revealed that a gradual increase in children's precision of top-down and bottom-up information as they develop effectively explains the observed change of drawing style from scribbling toward representational drawing. Furthermore, individual differences that are prevalent in children's drawings, might arise from different developmental pathways regarding the precision of these two signals. Based on these findings we propose a theory of how both general and individual development of drawing could be explained in a unified manner within the framework of predictive coding.

Ten easy steps to conducting transparent, reproducible meta-analyses for infant researchers.

Meta-analyses provide researchers with an overview of the body of evidence in a topic, with quantified estimates of effect sizes and the role of moderators, and weighting studies according to their precision. We provide a guide for conducting a transparent and reproducible meta-analysis in the field of developmental psychology within the framework of the MetaLab platform, in 10 steps: (1) Choose a topic for your meta-analysis, (2) Formulate your research question and specify inclusion criteria, (3) Preregister and document all stages of your meta-analysis, (4) Conduct the literature search, (5) Collect and screen records, (6) Extract data from eligible studies, (7) Read the data into analysis software and compute effect sizes, (8) Visualize your data, (9) Create meta-analytic models to assess the strength of the effect and investigate possible moderators, (10) Write up and promote your meta-analysis. Meta-analyses can inform future studies, through power calculations, by identifying robust methods and exposing research gaps. By adding a new meta-analysis to MetaLab, datasets across multiple topics of developmental psychology can be synthesized, and the dataset can be maintained as a living, community-augmented meta-analysis to which researchers add new data, allowing for a cumulative approach to evidence synthesis.

A Global Perspective on Testing Infants Online: Introducing ManyBabies-AtHome.

Online testing holds great promise for infant scientists. It could increase participant diversity, improve reproducibility and collaborative possibilities, and reduce costs for researchers and participants. However, despite the rise of platforms and participant databases, little work has been done to overcome the challenges of making this approach available to researchers across the world. In this paper, we elaborate on the benefits of online infant testing from a global perspective and identify challenges for the international community that have been outside of the scope of previous literature. Furthermore, we introduce ManyBabies-AtHome, an international, multi-lab collaboration that is actively working to facilitate practical and technical aspects of online testing and address ethical concerns regarding data storage and protection, and cross-cultural variation. The ultimate goal of this collaboration is to improve the method of testing infants online and make it globally available.

SCALa: A blueprint for computational models of language acquisition in social context.

Theories and data on language acquisition suggest a range of cues are used, ranging from information on structure found in the linguistic signal itself, to information gleaned from the environmental context or through social interaction. We propose a blueprint for computational models of the early language learner (SCALa, for Socio-Computational Architecture of Language Acquisition) that makes explicit the connection between the kinds of information available to the social learner and the computational mechanisms required to extract language-relevant information and learn from it. SCALa integrates a range of views on language acquisition, further allowing us to make precise recommendations for future large-scale empirical research.

Quantifying the role of rhythm in infants' language discrimination abilities: A meta-analysis.

More than 30 years have passed since Mehler et al. (1988) proposed that newborns can discriminate between languages that belong to different rhythm classes: stress-, syllable- or mora-timed. Thereupon they developed the hypothesis that infants are sensitive to differences in vowel and consonant interval durations as acoustic correlates of rhythm classes. It remains unknown exactly which durational computations infants use when perceiving speech for the purposes of distinguishing languages. Here, a meta-analysis of studies on infants' language discrimination skills over the first year of life was conducted, aiming to quantify how language discrimination skills change with age and are modulated by rhythm classes or durational metrics. A systematic literature search identified 42 studies that tested infants' (birth to 12 months) discrimination or preference of two language varieties, by presenting infants with auditory or audio-visual continuous speech. Quantitative data synthesis was conducted using multivariate random effects meta-analytic models with the factors rhythm class difference, age, stimulus manipulation, method, and metrics operationalising proportions of and variability in vowel and consonant interval durations, to explore which factors best account for language discrimination or preference. Results revealed that smaller differences in vowel interval variability (△V) and larger differences in successive consonantal interval variability (rPVI-C) were associated with more successful language discrimination, and better accounted for discrimination results than the factor rhythm class. There were no effects of age for discrimination but results on preference studies were affected by age: the older infants get, the more they prefer non-native languages that are rhythmically similar to their native language, but not non-native languages that are rhythmically distinct. These findings can inform theories on language discrimination that have previously focussed on rhythm class, by providing a novel way to operationalise rhythm in language in the extent to which it accounts for infants' language discrimination abilities.

Toddler word learning from contingent screens with and without human presence.

While previous studies have documented that toddlers learn less well from passive screens than from live interaction, the rise of interactive, digital screen media opens new perspectives, since some work has shown that toddlers can learn similarly well from a human present via video chat as from live exposure. The present study aimed to disentangle the role of human presence from other aspects of social interactions on learning advantages in contingent screen settings. We assessed 16-month-old toddlers' fast mapping of novel words from screen in three conditions: in-person, video chat, and virtual agent. All conditions built on the same controlled and scripted interaction. In the in-person condition, toddlers learned two novel word-object associations from an experimenter present in the same room and reacting contingently to infants' gaze direction. In the video chat condition, the toddler saw the experimenter in real time on screen, while the experimenter only had access to the toddler's real-time gaze position as captured by an eyetracker. This setup allowed contingent reactivity to the toddler's gaze while controlling for any cues beyond these instructions. The virtual agent condition was programmed to follow the infant's gaze, to smile, and to name the object with the same parameters as the experimenter in the other conditions. After the learning phase, all toddlers were tested on their word recognition in a looking-while-listening paradigm. Comparisons against chance revealed that toddlers showed above-chance word learning in the in-person group only. Toddlers in the virtual agent group showed significantly worse performance than those in the in-person group, while performance in the video chat group overlapped with the other two groups. These results confirm that in-person interaction leads to best learning outcomes even in the absence of rich social cues. They also elucidate that contingency is not sufficient either, and that in order for toddlers to learn from interactive digital media, more cues to social agency are required.

A meta-analysis of infants' word-form recognition.

Recognizing word forms is an important step on infants' way toward mastering their native language. The present study takes a meta-analytic approach to assess overarching questions on the literature of early word-form recognition. Specifically, we investigated the extent to which there is cross-linguistic evidence for an early recognition lexicon, and how it may be influenced by infant age, language background, and familiarity of the selected stimuli (approximated by parent-reported word knowledge). Our meta-analysis-with open data access on metalab.stanford.edu-was based on 32 experiments in 16 different published or unpublished studies on infants 5-15 months of age. We found an overall significant effect of word-form familiarity on infants' responses. This effect increased with age and was higher for infants learning Romance languages than other languages. We further found that younger, but not older, infants showed higher effect sizes for more familiar word lists. These insights should help researchers plan future studies on word-form recognition.

Preregistration in infant research-A primer.

Preregistration, the act of specifying a research plan in advance, is becoming more common in scientific research. Infant researchers contend with unique problems that might make preregistration particularly challenging. Infants are a hard-to-reach population, usually yielding small sample sizes, they can only complete a limited number of trials, and they can be excluded based on hard-to-predict complications (e.g., parental interference, fussiness). In addition, as effects themselves potentially change with age and population, it is hard to calculate an a priori effect size. At the same time, these very factors make preregistration in infant studies a valuable tool. A priori examination of the planned study, including the hypotheses, sample size, and resulting statistical power, increases the credibility of single studies and adds value to the field. Preregistration might also improve explicit decision making to create better studies. We present an in-depth discussion of the issues uniquely relevant to infant researchers, and ways to contend with them in preregistration and study planning. We provide recommendations to researchers interested in following current best practices.

Transparency and Reproducibility of Meta-Analyses in Psychology: A Meta-Review.

Systematic review and meta-analysis are possible as viable research techniques only through transparent reporting of primary research; thus, one might expect meta-analysts to demonstrate best practice in their reporting of results and have a high degree of transparency leading to reproducibility of their work. This assumption has yet to be fully tested in the psychological sciences. We therefore aimed to assess the transparency and reproducibility of psychological meta-analyses. We conducted a meta-review by sampling 150 studies from Psychological Bulletin to extract information about each review's transparent and reproducible reporting practices. The results revealed that authors reported on average 55% of criteria and that transparent reporting practices increased over the three decades studied (b = 1.09, SE = 0.24, t = 4.519, p < .001). Review authors consistently reported eligibility criteria, effect-size information, and synthesis techniques. Review authors, however, on average, did not report specific search results, screening and extraction procedures, and most importantly, effect-size and moderator information from each individual study. Far fewer studies provided statistical code required for complete analytical replication. We argue that the field of psychology and research synthesis in general should require review authors to report these elements in a transparent and reproducible manner.

Communicative cues in the absence of a human interaction partner enhance 12-month-old infants' word learning.

Is infants' word learning boosted by nonhuman social agents? An on-screen virtual agent taught infants word-object associations in a setup where the presence of contingent and referential cues could be manipulated using gaze contingency. In the study, 12-month-old Japanese-learning children (N = 36) looked significantly more to the correct object when it was labeled after exposure to a contingent and referential display versus a noncontingent and nonreferential display. These results show that communicative cues can augment learning even for a nonhuman agent, a finding highly relevant for our understanding of the mechanisms through which the social environment supports language acquisition and for research on the use of interactive screen media.

Promoting Replicability in Developmental Research Through Meta-analyses: Insights From Language Acquisition Research.

Previous work suggests that key factors for replicability, a necessary feature for theory building, include statistical power and appropriate research planning. These factors are examined by analyzing a collection of 12 standardized meta-analyses on language development between birth and 5 years. With a median effect size of Cohen's d = .45 and typical sample size of 18 participants, most research is underpowered (range = 6%-99%; median = 44%); and calculating power based on seminal publications is not a suitable strategy. Method choice can be improved, as shown in analyses on exclusion rates and effect size as a function of method. The article ends with a discussion on how to increase replicability in both language acquisition studies specifically and developmental research more generally.

Symbouki: a meta-analysis on the emergence of sound symbolism in early language acquisition.

Adults and toddlers systematically associate pseudowords such as "bouba" and "kiki" with round and spiky shapes, respectively, a sound symbolic phenomenon known as the "bouba-kiki effect". To date, whether this sound symbolic effect is a property of the infant brain present at birth or is a learned aspect of language perception remains unknown. Yet, solving this question is fundamental for our understanding of early language acquisition. Indeed, an early sensitivity to such sound symbolic associations could provide a powerful mechanism for language learning, playing a bootstrapping role in the establishment of novel sound-meaning associations. The aim of the present meta-analysis (SymBouKi) is to provide a quantitative overview of the emergence of the bouba-kiki effect in infancy and early childhood. It allows a high-powered assessment of the true sound symbolic effect size by pooling over the entire set of 11 extant studies (six published, five unpublished), entailing data from 425 participants between 4 and 38 months of age. The quantitative data provide statistical support for a moderate, but significant, sound symbolic effect. Further analysis found a greater sensitivity to sound symbolism for bouba-type pseudowords (i.e., round sound-shape correspondences) than for kiki-type pseudowords (i.e., spiky sound-shape correspondences). For the kiki-type pseudowords, the effect emerged with age. Such discrepancy challenges the view that sensitivity to sound symbolism is an innate language mechanism rooted in an exuberant interconnected brain. We propose alternative hypotheses where both innate and learned mechanisms are at play in the emergence of sensitivity to sound symbolic relationships.

The more, the better? Behavioral and neural correlates of frequent and infrequent vowel exposure.

A central assumption in the perceptual attunement literature holds that exposure to a speech sound contrast leads to improvement in native speech sound processing. However, whether the amount of exposure matters for this process has not been put to a direct test. We elucidated indicators of frequency-dependent perceptual attunement by comparing 5-8-month-old Dutch infants' discrimination of tokens containing a highly frequent [hɪt-he:t] and a highly infrequent [hʏt-hø:t] native vowel contrast as well as a non-native [hɛt-haet] vowel contrast in a behavioral visual habituation paradigm (Experiment 1). Infants discriminated both native contrasts similarly well, but did not discriminate the non-native contrast. We sought further evidence for subtle differences in the processing of the two native contrasts using near-infrared spectroscopy and a within-participant design (Experiment 2). The neuroimaging data did not provide additional evidence that responses to native contrasts are modulated by frequency of exposure. These results suggest that even large differences in exposure to a native contrast may not directly translate to behavioral and neural indicators of perceptual attunement, raising the possibility that frequency of exposure does not influence improvements in discriminating native contrasts.