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.
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.
•Rhythm class is limited in accounting for infants' language discrimination.•Infants' language discrimination is explained by durational rhythm metrics.•Discrimination improves as languages differ more in consonant interval variability.•Discrimination improves as languages differ less in vowel interval variability.•Preferences change with age depending on rhythmic similarity to native language.
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 learn novel word-object associations from a contingent and referential on-screen virtual agent.•They do not learn these associations from a non-contingent and non-referential virtual ...agent.•Communicative cues can augment learning even for a non-human agent.
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.
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.
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.
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.
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.
Our meta‐analysis shows a moderate, but significant sensitivity to sound‐symbolism in early language learning with greater sensitivity to bouba‐type than to kiki‐type pseudowords, with the latter emerging with age.
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