Representation of the gender of human faces by infants: a preference for female

Revisiting adolescence as a sensitive period for sociocultural processing

Waves of research and public discourse have characterized adolescence as periods of developmental risk and opportunity. Underlying this discussion is the recognition that adolescence is a period of major biological and social transition when experience may have an outsized effect on development. This article updates and expands upon prior work suggesting that adolescence may be a sensitive period for sociocultural processing specifically. By integrating evidence from developmental psychology and neuroscience, we identify how trajectories of social and neurobiological development may relate to adolescents' ability to adapt to and learn from their social environments. However, we also highlight gaps in the literature, including challenges in attributing developmental change to adolescent experiences. We discuss the importance of better understanding variability in biology (e.g., pubertal development) and cultural environments, as well as distinguishing between sensitive periods and periods of heightened sensitivity. Finally, we look toward future directions and translational implications of this research.

Endogenous Control and Reward-based Mechanisms Shape Infants' Attention Biases to Caregiver Faces

Infants rely on developing attention skills to identify relevant stimuli in their environments. Although caregivers are socially rewarding and a critical source of information, they are also one of many stimuli that compete for infants' attention. Young infants preferentially hold attention on caregiver faces, but it is unknown whether they also preferentially orient to caregivers and the extent to which these attention biases reflect reward-based attention mechanisms. To address these questions, we measured 4- to 10-month-old infants' (N = 64) frequency of orienting and duration of looking to caregiver and stranger faces within multi-item arrays. We also assessed whether infants' attention to these faces related to individual differences in Surgency, an indirect index of reward sensitivity. Although infants did not show biased attention to caregiver versus stranger faces at the group level, infants were increasingly biased to orient to stranger faces with age and infants with higher Surgency scores showed more robust attention orienting and attention holding biases to caregiver faces. These effects varied based on the selective attention demands of the task, suggesting that infants' attention biases to caregiver faces may reflect both developing attention control skills and reward-based attention mechanisms.

Plasticity in older infants' perception of phonetic contrasts: The role of selective attention in context

Developmental plasticity refers to conditions and circumstances that increase phenotypic variability. In infancy, plasticity expands and contracts depending on domains of functioning, developmental history, and timing. In terms of language processing, infants attend to and discriminate both native and non-native phonetic contrasts, but selectively attune to their native phonemes by the end of the first postnatal year. However, relevant studies have excluded factors regarded as promoters of attention such as infant-directed (ID) speech, synchronous multimodal presentations, and female speakers. Here we investigated whether English-learning 11-month-olds would discriminate a non-native phonetic contrast while manipulating these factors. Results showed significant discrimination of the non-native contrast, regardless of speech register, provided that they were presented by a dynamic female speaker. Interestingly, when a static object or a dynamic male ID speaker replaced the female, no significant discrimination was found. These results show infants to be capable of discriminating non-native phonetic contrasts in an enhanced context at an age when they have been characterized as not being able to do so. Synchronized, multimodal information from female speakers allowed infants to perceive difficult non-native phonemes, highlighting the importance of an ecologically valid context for studying speech perception and language learning in early development.

Measuring Embodiment: Movement Complexity and the Impact of Personal Characteristics

A user's personal experiences and characteristics may impact the strength of an embodiment illusion and affect resulting behavioral changes in unknown ways. This paper presents a novel re-analysis of two fully-immersive embodiment user-studies (n = 189 and n = 99) using structural equation modeling, to test the effects of personal characteristics on subjective embodiment. Results demonstrate that individual characteristics (gender, participation in science, technology, engineering or math - Experiment 1, age, video gaming experience - Experiment 2) predicted differing self-reported experiences of embodiment Results also indicate that increased self-reported embodiment predicts environmental response, in this case faster and more accurate responses within the virtual environment. Importantly, head-tracking data is shown to be an effective objective measure for predicting embodiment, without requiring researchers to utilize additional equipment.

A transdisciplinary view on curiosity beyond linguistic humans: animals, infants, and artificial intelligence

Curiosity is a core driver for life-long learning, problem-solving and decision-making. In a broad sense, curiosity is defined as the intrinsically motivated acquisition of novel information. Despite a decades-long history of curiosity research and the earliest human theories arising from studies of laboratory rodents, curiosity has mainly been considered in two camps: 'linguistic human' and 'other'. This is despite psychology being heritable, and there are many continuities in cognitive capacities across the animal kingdom. Boundary-pushing cross-disciplinary debates on curiosity are lacking, and the relative exclusion of pre-linguistic infants and non-human animals has led to a scientific impasse which more broadly impedes the development of artificially intelligent systems modelled on curiosity in natural agents. In this review, we synthesize literature across multiple disciplines that have studied curiosity in non-verbal systems. By highlighting how similar findings have been produced across the separate disciplines of animal behaviour, developmental psychology, neuroscience, and computational cognition, we discuss how this can be used to advance our understanding of curiosity. We propose, for the first time, how features of curiosity could be quantified and therefore studied more operationally across systems: across different species, developmental stages, and natural or artificial agents.

Who spoke that language? Assessing early face-language associations in monolingual and bilingual infants

Introduction

In bilingual communities, knowing the language each speaker uses may support language separation and, later, guide language use in a context-appropriate manner. Previous research has shown that infants begin to form primary associations between the face and the language used by a speaker around the age of 3 months. However, there is still a limited understanding of how robust these associations are and whether they are influenced by the linguistic background of the infant. To answer these questions, this study explores monolingual and bilingual infants' ability to form face-language associations throughout the first year of life.

Methods

A group of 4-, 6-, and 10-month-old Spanish and/or Catalan monolingual and bilingual infants were tested in an eye-tracking preferential-looking paradigm (N = 156). After the infants were familiarized with videos of a Catalan and a Spanish speaker, they were tested in two types of test trials with different task demands. First, a Silent test trial assessed primary face-language associations by measuring infants' visual preference for the speakers based on the language they had previously used. Then, two Language test trials assessed more robust face-language associations by measuring infants' ability to match the face of each speaker with their corresponding language.

Results

When measuring primary face-language associations, both monolingual and bilingual infants exhibited language-based preferences according to their specific exposure to the languages. Interestingly, this preference varied with age, with a transition from an initial familiarity preference to a novelty preference in older infants. Four-month-old infants showed a preference for the speaker who used their native/dominant language, while 10-month-old infants preferred the speaker who used their non-native/non-dominant language. When measuring more robust face-language associations, infants did not demonstrate signs of consistently matching the faces of the speakers with the language they had previously used, regardless of age or linguistic background.

Discussion

Overall, the results indicate that while both monolingual and bilingual infants before the first year of life can form primary face-language associations, these associations remain fragile as infants seemed unable to maintain them when tested in a more demanding task.

Women are expected to smile: Preliminary evidence for the role of gender in the neurophysiological processing of adult emotional faces in 3-year-old children

Children form stereotyped expectations about the appropriateness of certain emotions for men versus women during the preschool years, based on cues from their social environments. Although ample research has examined the development of gender stereotypes in children, little is known about the neural responses that underlie the processing of gender-stereotyped emotions in children. Therefore, the current study examined whether 3-year-olds differ in the neural processing of emotional stimuli that violate gender stereotypes (i.e., male faces with fearful or happy expressions) or confirm gender stereotypes (i.e., female faces with fearful or happy expressions), and whether boys and girls differ in their neural processing of the violation and confirmation of gender stereotypes. Data from 72 3-year-olds (±6 months, 43% boy) were obtained from the YOUth Cohort Study. Electroencephalography data were obtained when children passively viewed male and female faces displaying neutral, happy, or fearful facial expressions. This study provided first indications that happy male faces elicited larger P1 amplitudes than happy female faces in preschool children, which might reflect increased attentional processing of stimuli that violate gender stereotypes. Moreover, there was preliminary evidence that girls had larger negative central (Nc) responses, associated with salience processing, toward female happy faces than male happy faces, whereas boys had larger Nc responses toward male happy faces than female happy faces. No gender differences were found in the processing of neutral and fearful facial expressions. Our results indicate that electroencephalography measurements can provide insights into preschoolers' gender-stereotype knowledge about emotions, potentially by looking at the early occipital and late fronto-central responses.

Development of implicit and explicit attentional modulation of the processing of social cues conveyed by faces and bodies in children and adolescents

Emotions and sex of other people shape the way we interact in social environments. The influence of these dimensions on cognitive processing is recognized as a highly conditional phenomenon. While much of researches on the topic focused on adults, less evidence is available for the pediatric population. This study aimed at examining the development of the modulation of attention control on emotion and sex processing using facial and body expressions in children and adolescents (8–16 years old). In Experiment 1a, participants performed a Flanker task (probing space-based attention) in which they had to indicate either the emotion (happy/fearful) or the sex of the target stimulus while ignoring the distracting stimuli at the side. We found evidence for intrusion of the sex, but not emotion, of the stimuli during both sex and emotion recognition tasks, thus both at an explicit (i.e., task relevant) and implicit (i.e., task irrelevant) level. A control experiment consisting of an emotional Flanker task confirmed that, in contrast with previous findings in adults, emotion did not modulate attention control in children and adolescents even when task relevant (Experiment 1b). In Experiment 2 participants performed a same-or-different judgment task (probing feature-based attention) in which they indicated whether the central stimulus matched the lateral ones for emotion or sex. Results showed that emotional features exerted an implicit influence during sex judgements; likewise, sex features intruded on the processing of both faces and bodies during emotion judgments. Finally, Experiment 3 explored the development of the explicit attention modulation exerted by the sex dimension on the processing of faces and bodies. To this aim, participants performed a Flanker task in which they were asked to recognize the sex of faces and bodies. The results indicated that, while younger participants showed a task-relevant influence of sexual features when processing faces, older participants showed such influence when processing bodies. These findings point to a greater attentional modulation exerted by sex, as compared to emotion, during social processing in children and adolescents and suggest a developmental trend of the saliency of facial and bodily cues for the perception of others’ sex.

Combining wearable fNIRS and immersive virtual reality to study preschoolers' social development: a proof-of-principle study on preschoolers' social preference

A child's social world is complex and rich, but has traditionally been assessed with conventional experiments where children are presented with repeated stimuli on a screen. These assessments are impoverished relative to the dynamics of social interactions in real life, and can be challenging to implement with preschoolers, who struggle to comply with strict lab rules. The current work meets the need to develop new platforms to assess preschoolers' social development, by presenting a unique virtual-reality set-up combined with wearable functional near-infrared spectroscopy (fNIRS). As a proof-of-principle, we validated this platform by measuring brain activity during self-guided social interaction in 3-to-5-year-olds, which is under-investigated, yet crucial to understand the basis of social interactions in preschoolers. 37 preschoolers chose an interaction partner from one of 4 human-like avatars of different gender and age. We recorded spontaneous brain fluctuations from the frontal and temporoparietal regions (notably engaged in social-categorization and preference) while children played a bubble-popping game with a preferred and an assigned avatar. 60% of the participants chose to play with the same-gender and same-age avatar. However, this result was driven by females (>80% vs. 50% in males). Different fronto-temporoparietal connectivity patterns when playing with the two avatars were observed, especially in females. We showed the feasibility of using a novel set-up to naturalistically assess social preference in preschoolers, which was assessed at the behavioural and functional connectivity level. This work provides a first proof-of-principle for using cutting-edge technologies and naturalistic experiments to study social development, opening new avenues of research.

Toddlers' sensitivity to dominance traits from faces

In adults, seeing individual faces is sufficient to trigger dominance evaluations, even when conflict is absent. From early on, infants represent dyadic dominance relations and they can infer conflict outcomes based on a variety of cues. To date, it is unclear if toddlers also make automatic dominance trait evaluations of individual faces. Here we asked if toddlers are sensitive to dominance traits from faces, and whether their sensitivity depends on their face experience. We employed a visual preference paradigm to study 18- and 24-month-old toddlers' sensitivity to dominance traits from three types of faces: artificial, male, female. When presented with artificial faces (Experiment 1), 18- and 24-month-olds attended longer to the non-dominant faces, but only when they were in upright orientation. For real male faces (Experiment 2), toddlers showed equivalent looking durations to the dominant and non-dominant upright faces. However, when looking at female faces (Experiment 3), toddlers displayed a visual preference for the upright non-dominant faces at 24 months. To our knowledge, this is the first study to show that toddlers already display sensitivity to facial cues of dominance from 18 months of age, at least for artificial face stimuli.

Transgender and Gender Diverse Identity Development in Pediatric Populations

Gender identity development is conceptualized as a biopsychosocial process that is influenced by broader historical, social, and cultural contextual factors. This review outlines the current understanding of the biopsychosocial and contextual factors that influence gender identity development in children and adolescents. Developmental milestones for gender identity development in youth are presented, and unique developmental needs for transgender and gender diverse (TGD) youth are reviewed. This article also reviews emerging areas of relevance for TGD populations, such as detransitioning and transition regret. Clinicians working with TGD populations should aim to develop individualized, evidence-based care plans that flexibly meet each youth's distinct developmental and contextual psychosocial and health care needs. [Pediatr Ann. 2023;52(12):e450-e455.].

Recognition of humans from biological motion in infants

Infant studies have suggested that the detection of biological motion (BM) might be an innate capacity, based on newborns' spontaneous preference for BM. However, it is unclear if, like adults, infants recognize humans from BM and are able to build the representation of bodies and faces. To address this issue, we tested whether exposure to BM influences subsequent face recognition in 3- to 8-month-old infants. After familiarization with a point-light walker (PLW) of either a female or a male, the infant's preference for female and male faces was measured. If infants can build the representation of not only the body but also the face from PLWs, the familiarization effect of gender induced by the PLW might be generalized to faces. We found that infants at 7 to 8 months looked for longer at the face whose gender was opposite to that of the PLW, whereas 3- to 4- and 5- to 6-month-old infants did not. These results suggest that infants can access the representation of humans from BM and extract gender, which is shared across bodies and faces, from at least 7 to 8 months of age.

Community diversity and the other-race effect in infancy

The other-race effect (ORE) is characterized by processing advantages for faces of one's own race over faces of another race and is observed at ~9 months of age. Environmental exposure to other races has an impact on the development of the ORE. In the current study, we examined the effects of community racial diversity on the ORE in 9- to 12-month-olds from across the United States. We hypothesized that community racial diversity would influence the amount of experience that infants have with individuals of other races and be an important factor in predicting the ORE across broad regions of the United States. We predicted that infants from more diverse communities would demonstrate successful processing of own- and other-race faces, while infants from less diverse communities would demonstrate successful processing of own-race but not other-race faces. This would indicate that the ORE is exhibited more strongly in infants from less diverse communities than in infants from more diverse communities. Participants completed familiarization and visual paired comparison (VPC) trials with own- and other-race faces in an online study. Our results showed that although the ORE was present, the effect was driven by community members who were the racial majority. Recognition biases were not observed in community racial or ethnic minority participants, potentially due to increased exposure to racial out-group members, which mitigated the development of the ORE in this subset of participants. This study has far-reaching implications in the study of infant face perception, child development, and social justice, as the ORE develops at a young age, and may lead to a complex pattern of racial biases contributing to systemic barriers in society.

Linguistic identity as a modulator of gaze cueing of attention

Eye-gaze stimuli can elicit orienting of attention in an observer, a phenomenon known as gaze cueing of attention. Here, we explored whether gaze cueing can be shaped by the linguistic identity of the cueing face. In two experiments, participants were first familiarized with different faces together with auditory sentences. Half of the sentences were associated with the native language of the participants (Italian) and the other half with an unknown language (Albanian and Basque, in Experiments 1 and 2, respectively). In a second phase, participants performed a gaze-cueing task. In a third recognition phase, the auditory sentences were presented again, and participants were required to decide which face uttered each sentence. Results indicated that participants were more likely to confuse faces from the same language category than from the other language category. Results of the gaze-cueing task revealed a greater gaze-cueing effect for faces associated with the native vs. unknown language. Critically, this difference emerged only in Experiment 1, which may reflect differences in social status between the two language groups. Our findings revealed the impact of language as a social cue on the gaze-cueing effect, suggesting that social attention is sensitive to the language of our interlocutors.

Authentic gender development in non-binary children

At present, the conceptualization of gender as a spectrum as well as non-binary identities have become increasingly visible and embraced. We are using non-binary as an umbrella term that refers to individuals who self-identify as a gender outside the gender binary, and/or who do not identify as always and completely being just a man or a woman. Our goal is to begin to create a framework for understanding gender development in non-binary children ages 0 to 8, since previous models have operated on cissupremacist assumptions, not applicable to non-binary people. As there is virtually no empirical data on the subject, we conducted a thorough literature review of current gender development theories and used our positionality as non-binary researchers to postulate two minimum criteria for non-binary gender identification: that a child learns about the existence of non-binary identities, and that they do not identify with the definitions they have been taught of what a boy or girl is. Children can learn about non-binary identities through media and knowledgeable community members and can develop "gender traits" authentically and come to identify as non-binary through biological predispositions, parental support, modeling, and being in peer groups that are supportive of identity exploration. Yet, children are not simply a product of their nature and nurture, as evidence has shown that humans are active agents in their gender development from a young age.

Children perceive illusory faces in objects as male more often than female

Face pareidolia is the experience of seeing illusory faces in inanimate objects. While children experience face pareidolia, it is unknown whether they perceive gender in illusory faces, as their face evaluation system is still developing in the first decade of life. In a sample of 412 children and adults from 4 to 80 years of age we found that like adults, children perceived many illusory faces in objects to have a gender and had a strong bias to see them as male rather than female, regardless of their own gender identification. These results provide evidence that the male bias for face pareidolia emerges early in life, even before the ability to discriminate gender from facial cues alone is fully developed. Further, the existence of a male bias in children suggests that any social context that elicits the cognitive bias to see faces as male has remained relatively consistent across generations.

Infant negative affectivity and patterns of affect-biased attention

Biased attention toward affective cues often cooccurs with the emergence and maintenance of internalizing disorders. However, few studies have assessed whether affect-biased attention in infancy relates to early indicators of psychopathological risk, such as negative affectivity. The current study evaluates whether negative affectivity relates to affect-biased attention in 6-month-old infants. Affect-biased attention was assessed via a free-viewing eye-tracking task in which infants were presented with a series of face pairs (comprised of a happy, angry, or sad face and a neutral face). Attention was quantified with metrics of both attention orienting and attention holding. Overall, infants showed no differences in attention orienting (i.e., speed of looking) or attention holding (i.e., duration of looking) toward emotional faces in comparison to the neutral face pairs. Negative affectivity, assessed via parent report, did not relate to attention orienting but was associated with biased attention toward positive, happy faces and away from threat-cueing, angry faces in comparison to the neutral faces they were paired with. These findings suggest that negative affectivity is associated with differences in attention holding, but not initial orienting toward emotional faces; biases which have important implications for the trajectory of socioemotional development.

Diversity vs. ingroup: How children generalize for the common good

How do children generalize for the common good? The present study investigated whether children are more likely to use the preference of their ingroup (ingroup rationale) or that of a diverse group (diversity rationale) as a basis for generalization about the broader community. In a series of studies, five-year-olds from two different cultures (US and China), yet living in environments with analogous ingroup majority-outgroup minority structure, were asked to generalize either the preference of a diverse sample or the preference of an ingroup sample to the majority. We found that children from both cultures have a default strategy to generalize from their ingroup (Study 1). However, Studies 2-4 show that this ingroup default is amenable to change, suggesting that children mostly use this strategy because ingroup members were salient and conveniently available. When ingroup was removed or reduced (Study 2), or when primed with photos of diverse populations (Studies 3 & 4), children changed their strategies and were more likely to use the diversity-rationale. In both cultures, the intergroup structure of children's living environment exerts similar pressures, resulting in analogous outcomes in generalizing for the common good.

Face race and sex impact visual fixation strategies for upright and inverted faces in 3- to 6-year-old children

Everyday face experience tends to be biased, such that infants and young children interact more often with own-race and female faces leading to differential processing of faces within these groups relative to others. In the present study, visual fixation strategies were recorded using eye tracking to determine the extent to which face race and sex/gender impact a key index of face processing in 3- to 6-year-old children (n = 47). Children viewed male and female upright and inverted White and Asian faces while visual fixations were recorded. Face orientation was found to have robust effects on children's visual fixations, such that children exhibited shorter first fixation and average fixation durations and a greater number of fixations for inverted compared to upright face trials. First fixations to the eye region were also greater for upright compared to inverted faces. Fewer fixations and longer duration fixations were found for trials with male compared to female faces and for upright compared to inverted unfamiliar-race faces, but not familiar-race faces. These findings demonstrate evidence of differential fixation strategies toward different types of faces in 3- to 6-year-old children, illustrating the importance of experience in the development of visual attention to faces.

Oxytocin attenuates racial categorization in 14-month-old infants

Intergroup bias - the preferential attitudes one holds towards one's social group - is a ubiquitous socio-cognitive phenomenon. In fact, studies show that already in the first months of life, infants manifest a preference for members of their own social group. This points to the possibility of inborn mechanisms involved in social group cognition. Here we assess the effect of a biological activation of infants' affiliative motivation on their social categorization capacity. In a first visit to the lab, mothers self-administered either Oxytocin (OT) or placebo (PL) via a nasal spray and then engaged in a face-to-face interaction with their 14-month-old infants, a procedure previously shown to increase OT levels in infants. Infants then performed a racial categorization task presented on an eye-tracker. Mothers and infants returned a week later and repeated the procedure while self-administering the complementary substance (i.e., PL or OT, respectively). In total, 24 infants completed the two visits. We found that whereas infants in the PL condition on the first visit exhibited racial categorization, infants in the OT condition in their first visit did not. Moreover, these patterns remained a week later despite the change in substance. Thus, OT inhibited racial categorization when infants first encountered the to-be-categorized faces. These findings highlight the role of affiliative motivation in social categorization, and suggest that the neurobiology of affiliation may provide insights on mechanisms that may be involved in the downstream prejudicial consequences of intergroup bias.

No strong evidence for universal gender differences in the development of cooperative behaviour across societies

Human cooperation varies both across and within societies, and developmental studies can inform our understanding of the sources of both kinds of variation. One key candidate for explaining within-society variation in cooperative behaviour is gender, but we know little about whether gender differences in cooperation take root early in ontogeny or emerge similarly across diverse societies. Here, we explore two existing cross-cultural datasets of 4- to 15-year-old children's preferences for equality in experimental tasks measuring prosociality (14 societies) and fairness (seven societies), and we look for evidence of (i) widespread gender differences in the development of cooperation, and (ii) substantial societal variation in gender differences. This cross-cultural approach is crucial for revealing universal human gender differences in the development of cooperation, and it helps answer recent calls for greater cultural diversity in the study of human development. We find that gender has little impact on the development of prosociality and fairness within these datasets, and we do not find much evidence for substantial societal variation in gender differences. We discuss the implications of these findings for our knowledge about the nature and origin of gender differences in cooperation, and for future research attempting to study human development using diverse cultural samples. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

The effect of masks on the visual preference for faces in the first year of life

To prevent the spread of COVID-19, face masks were mandatory in many public spaces around the world. Since faces are the gateway to early social cognition, this raised major concerns about the effect face masks may have on infants' attention to faces as well as on their language and social development. The goal of the present study was to assess how face masks modulate infants' attention to faces over the course of the first year of life. We measured 3, 6, 9, and 12-month-olds' looking behavior using a paired visual preference paradigm under two experimental conditions. First, we tested infants' preference for upright masked or unmasked faces of the same female individual. We found that regardless of age, infants looked equally long at the masked and unmasked faces. Second, we compared infants' attention to an upright masked versus an inverted masked face. Three- and 6-month-olds looked equally long to the masked faces when they were upright or inverted. However, 9- and 12-month-old infants showed a novelty preference for the inverted masked face. Our findings suggest that more experience with faces, including masked faces, leads to efficient adaptations of infants' visual system for processing impoverished social stimuli, such as partially occluded faces.

Face processing in the infant brain after pandemic lockdown

The role of visual experience in the development of face processing has long been debated. We present a new angle on this question through a serendipitous study that cannot easily be repeated. Infants viewed short blocks of faces during fMRI in a repetition suppression task. The same identity was presented multiple times in half of the blocks (repeat condition) and different identities were presented once each in the other half (novel condition). In adults, the fusiform face area (FFA) tends to show greater neural activity for novel versus repeat blocks in such designs, suggesting that it can distinguish same versus different face identities. As part of an ongoing study, we collected data before the COVID-19 pandemic and after an initial local lockdown was lifted. The resulting sample of 12 infants (9-24 months) divided equally into pre- and post-lockdown groups with matching ages and data quantity/quality. The groups had strikingly different FFA responses: pre-lockdown infants showed repetition suppression (novel > repeat), whereas post-lockdown infants showed the opposite (repeat > novel), often referred to as repetition enhancement. These findings provide speculative evidence that altered visual experience during the lockdown, or other correlated environmental changes, may have affected face processing in the infant brain.

Gender Development in Gender Diverse Children

Within "mainstream" developmental science, gender researchers largely study the developmental trajectory of children considered to be "gender-typical", while research housed primarily in psychiatry and clinical psychology often documents the trajectories of gender diverse children. This article aims to bridge the studies of gender diversity and "mainstream" gender development. First, we review literature on the development of four commonly studied subgroups of gender diverse children - children referred to medical clinics because of their gender identity and expression, transgender children, female children with congenital adrenal hyperplasia, and tomboys - highlighting how these gender trajectories do or do not align with modal developmental patterns. We then describe social, cognitive, and biological determinants of gender in light of their implications for understanding diverse gender development. Finally, we note methodological suggestions for future research, with an eye toward better integrating research on gender diversity into "mainstream" gender development research.

Language as a cue for social categorization in bilingual communities

This registered report article investigates the role of language as a dimension of social categorization. Our critical aim was to investigate whether categorization based on language occurs even when the languages coexist within the same sociolinguistic context, as is the case in bilingual communities. Bilingual individuals of two bilingual communities, the Basque Country (Spain) and Veneto (Italy), were tested using the memory confusion paradigm in a 'Who said what?' task. In the encoding part of the task, participants were presented with different faces together with auditory sentences. Two different languages of the sentences were presented in each study, with half of the faces always associated with one language and the other half with the other language. Spanish and Basque languages were used in Study 1, and Italian and Venetian dialect in Study 2. In the test phase, the auditory sentences were presented again and participants were required to decide which face uttered each sentence. As expected, participants error rates were high. Critically, participants were more likely to confuse faces from the same language category than from the other (different) language category. The results indicate that bilinguals categorize individuals belonging to the same sociolinguistic community based on the language these individuals speak, suggesting that social categorization based on language is an automatic process.

Understanding trait impressions from faces

Impressions from faces are made remarkably quickly and they can underpin behaviour in a wide variety of social contexts. Over the last decade many studies have sought to trace the links between facial cues and social perception and behaviour. One such body of work has shown clear overlap between the fields of face perception and social stereotyping by demonstrating a role for conceptual stereotypes in impression formation from faces. We integrate these results involving conceptual influences on impressions with another substantial body of research in visual cognition which demonstrates that much of the variance in impressions can be predicted from perceptual, data-driven models using physical cues in face images. We relate this discussion to the phylogenetic, cultural, individual and developmental origins of facial impressions and define priority research questions for the field including investigating non-WEIRD cultures, tracking the developmental trajectory of impressions and determining the malleability of impression formation.

Construal level mindsets modulate gender categorizations in preschool children

Social categorization is a crucial information processing strategy that adults deliberately adjust depending on goals and situational requirements. This study investigated whether flexibility in categorization is similarly present among preschool children. More specifically, we tested whether spontaneous gender categorizations are more pronounced for children with a situationally induced abstract compared to concrete construal level mindset. Sixty-one children first participated in a construal mindset induction task before completing a visual variant of the "who said what" memory task. Systematic memory confusions indicated that all children engaged in gender-based social categorization but that this tendency was accentuated in the abstract compared to concrete mindset condition. These results suggest an ability of children to modulate social categorizations. Implications for the development of intergroup biases are discussed.

Maturational trajectory of fusiform gyrus neural activity when viewing faces: From 4 months to 4 years old

Infant and young child electrophysiology studies have provided information regarding the maturation of face-encoding neural processes. A limitation of previous research is that very few studies have examined face-encoding processes in children 12-48 months of age, a developmental period characterized by rapid changes in the ability to encode facial information. The present study sought to fill this gap in the literature via a longitudinal study examining the maturation of a primary node in the face-encoding network-the left and right fusiform gyrus (FFG). Whole-brain magnetoencephalography (MEG) data were obtained from 25 infants with typical development at 4-12 months, and with follow-up MEG exams every ∼12 months until 3-4 years old. Children were presented with color images of Face stimuli and visual noise images (matched on spatial frequency, color distribution, and outer contour) that served as Non-Face stimuli. Using distributed source modeling, left and right face-sensitive FFG evoked waveforms were obtained from each child at each visit, with face-sensitive activity identified via examining the difference between the Non-Face and Face FFG timecourses. Before 24 months of age (Visits 1 and 2) the face-sensitive FFG M290 response was the dominant response, observed in the left and right FFG ∼250-450 ms post-stimulus. By 3-4 years old (Visit 4), the left and right face-sensitive FFG response occurred at a latency consistent with a face-sensitive M170 response ∼100-250 ms post-stimulus. Face-sensitive left and right FFG peak latencies decreased as a function of age (with age explaining greater than 70% of the variance in face-sensitive FFG latency), and with an adult-like FFG latency observed at 3-4 years old. Study findings thus showed face-sensitive FFG maturational changes across the first 4 years of life. Whereas a face-sensitive M290 response was observed under 2 years of age, by 3-4 years old, an adult-like face-sensitive M170 response was observed bilaterally. Future studies evaluating the maturation of face-sensitive FFG activity in infants at risk for neurodevelopmental disorders are of interest, with the present findings suggesting age-specific face-sensitive neural markers of a priori interest.

Which group matters more: The relative strength of minimal vs. gender and race group memberships in children's intergroup thinking

Experimentally created "minimal" social groups are frequently used as a means to investigate core components of intergroup cognition in children and adults. Yet, it is unclear how the effects of such arbitrary group memberships compare to those of salient real-world group memberships (gender and race) when they are directly pitted against each other in the same studies. Across three studies, we investigate these comparisons in 4-7-year-olds. Study 1 (N = 48) establishes the minimal group paradigm, finding that children develop ingroup preferences as well as other forms of group-based reasoning (e.g., moral obligations) following random assignment to a minimal group. Study 2 (N = 96) and Study 3 (N = 48) directly compare this minimal group to a real-world social group (gender or race) in a cross-categorization paradigm, in which targets are participants' ingroups in terms of the minimal group and outgroups in terms of a real-world social group, or vice versa. The relative strength of the minimal group varies, but in general it either has a similar effect or a stronger effect as compared to race and in some cases even gender. Our results support the contention that an abstract tendency to divide the world into "us" and "them" is a central force in early intergroup cognition.

Asymmetrical responding to male versus female other-race categories in 9- to 12-month-old infants

Faces can be categorized along various dimensions including gender or race, an ability developing in infancy. Infant categorization studies have focused on facial attributes in isolation, but the interaction between these attributes remains poorly understood. Experiment 1 examined gender categorization of other-race faces in 9- and 12-month-old White infants. Nine- and 12-month-olds were familiarized with Asian male or female faces, and tested with a novel exemplar from the familiarized category paired with a novel exemplar from a novel category. Both age groups showed novel category preferences for novel Asian female faces after familiarization with Asian male faces, but showed no novel category preference for novel Asian male faces after familiarization with Asian female faces. This categorization asymmetry was not due to a spontaneous preference hindering novel category reaction (Experiment 2), and both age groups displayed difficulty discriminating among male, but not female, other-race faces (Experiment 3). These results indicate that category formation for male other-race faces is mediated by categorical perception. Overall, the findings suggest that even by 12 months of age, infants are not fully able to form gender category representations of other-race faces, responding categorically to male, but not female, other-race faces.

Nonverbal emotion perception and vocabulary in late infancy

Language has been proposed as a potential mechanism for young children's developing understanding of emotion. However, much remains unknown about this relation at an individual difference level. The present study investigated 15- to 18-month-old infants' perception of emotions across multiple pairs of faces. Parents reported their child's productive vocabulary, and infants participated in a non-linguistic emotion perception task via an eye tracker. Infant vocabulary did not predict nonverbal emotion perception when accounting for infant age, gender, and general object perception ability (β = -0.15, p = .300). However, we observed a gender difference: Only girls' vocabulary scores related to nonverbal emotion perception when controlling for age and general object perception ability (β = 0.42, p = .024). Further, boys showed a stronger preference for the novel emotion face vs. girls (t(48) = 2.35, p = .023, d= 0.67). These data suggest that pathways of processing emotional information (e.g., using language vs visual information) may differ for girls and boys in late infancy.

Infant sensitivity to age-based social categories in full-body displays

This study examined 3.5- and 6-month-old infants' visual preferences for individuals from different age groups: adults versus infants. Unlike previous studies that only studied faces, here we included bodies, which are as frequent as faces in our environment, and highly salient, and in consequence, may play a role in identifying social categories and driving social preferences. In particular, we studied three salient dimensions along which individuals of different ages differ: body length, body typology, and face typology. In Experiment 1, adult and infant stimuli were presented in real proportions, differing both in body length and face typology, and infants preferred the adult stimuli. Experiment 2 demonstrated that given identical adult stimuli, which differ only in body length, infants attended more to the longer stimuli. In Experiment 3, infant and adult stimuli were matched on body length with the infant stimuli having larger heads, and infants preferred the infant stimuli. Experiment 4 measured infant visual preference for infant or adult bodies in the absence of face information, and found that 4-month-olds attended more to the infant bodies. Experiment 5 measured infants' sensitivity to matching or mismatching faces and bodies based on age, and infants demonstrated a preference for the incongruent stimuli (i.e., adult head with an infant body). Altogether these studies show that while face typology and body size are main drivers of infant visual preference for adults, when body typology information is provided for bodies matched in size, infant preference shifts towards their peers. Thus, our results suggest that infants have early developing age-based body representations, and that body information shifts their pattern of visual behavior from a visual preference for adult faces, to a visual preference for full-body peers.

Seven-month-old infants detect symmetrical structures in multi-featured abstract visual patterns

The present study investigated 7-month-old infants' ability to perceive structural symmetry in mosaic-like abstract visual patterns. We examined infants' (n = 98) spontaneous looking behaviour to mosaic-like sequences with symmetrical and asymmetrical structures. Sequences were composed of square tiles from two categories that differed in their colour scheme and internal shape. We manipulated sequence length (3 or 5 tiles) and abstractness of the symmetry (token vs. category level). The 7-month-olds discriminated structurally symmetrical from asymmetrical mosaics in the first half of the test phase (first 8 trials). Sequence length, level of symmetry, or number of unique tiles per sequence did not significantly modulate infants' looking behaviour. These results suggest that very young infants detect differences in structural symmetry in multi-featured visual patterns.

The Detection of Face-like Stimuli at the Edge of the Infant Visual Field

Human infants are highly sensitive to social information in their visual world. In laboratory settings, researchers have mainly studied the development of social information processing using faces presented on standard computer displays, in paradigms exploring face-to-face, direct eye contact social interactions. This is a simplification of a richer visual environment in which social information derives from the wider visual field and detection involves navigating the world with eyes, head and body movements. The present study measured 9-month-old infants’ sensitivities to face-like configurations across mid-peripheral visual areas using a detection task. Upright and inverted face-like stimuli appeared at one of three eccentricities (50°, 55° or 60°) in the left and right hemifields. Detection rates at different eccentricities were measured from video recordings. Results indicated that infant performance was heterogeneous and dropped beyond 55°, with a marginal advantage for targets appearing in the left hemifield. Infants’ orienting behaviour was not influenced by the orientation of the target stimulus. These findings are key to understanding how face stimuli are perceived outside foveal regions and are informative for the design of infant paradigms involving stimulus presentation across a wider field of view, in more naturalistic visual environments.

A New Perspective on Assessing Cognition in Children through Estimating Shared Intentionality

This theoretical article aims to create a conceptual framework for future research on digital methods for assessing cognition in children through estimating shared intentionality, different from assessing through behavioral markers. It shows the new assessing paradigm based directly on the evaluation of parent-child interaction exchanges (protoconversation), allowing early monitoring of children’s developmental trajectories. This literature analysis attempts to understand how cognition is related to emotions in interpersonal dynamics and whether assessing these dynamics shows cognitive abilities in children. The first part discusses infants’ unexpected achievements, observing the literature about children’s development. The analysis supposes that due to the caregiver’s help under emotional arousal, newborns’ intentionality could appear even before it is possible for children’s intention to occur. The emotional bond evokes intentionality in neonates. Therefore, they can manifest unexpected achievements while performing them with caregivers. This outcome shows an appearance of protoconversation in adult-children dyads through shared intentionality. The article presents experimental data of other studies that extend our knowledge about human cognition by showing an increase of coordinated neuronal activities and the acquisition of new knowledge by subjects in the absence of sensory cues. This highlights the contribution of interpersonal interaction to gain cognition, discussed already by Vygotsky. The current theoretical study hypothesizes that if shared intentionality promotes cognition from the onset, this interaction modality can also facilitate cognition in older children. Therefore in the second step, the current article analyzes empirical data of recent studies that reported meaningful interaction in mother-infant dyads without sensory cues. It discusses whether an unbiased digital assessment of the interaction ability of children is possible before the age when the typical developmental trajectory implies verbal communication. The article develops knowledge for a digital assessment that can measure the extent of children’s ability to acquire knowledge through protoconversation. This specific assessment can signalize the lack of communication ability in children even when the typical trajectory of peers’ development does not imply verbal communication.

The "Fat Face" illusion: A robust adaptation for processing pairs of faces

Converging evidence has demonstrated our remarkable capacities to process individual faces. However, in real-life contexts, we rarely see faces in isolation. It is largely unknown how our visual system processes a multitude of faces. The current study explored this question by using the "Fat Face" illusion: when two identical faces are vertically aligned, the bottom face appears bigger. In Experiment 1, we tested the robustness of this illusion by using faces varied by gender and race, by recruiting participants from different countries (Canadian, Chinese, and French), and by implementing different task requirements. We found that the illusion was stable and immune to variations in face gender or face race, perceptual familiarity, and task requirements. Experiment 2 further indicated that binocular vision was essential for this visual illusion. When participants performed the task with one eye covered, the previously robust illusion completely disappeared. Together, these findings revealed a visual adaptation for processing multiple faces in the environment: the face at the top is perceived as more distant from the viewer and appears smaller in size than the face at the bottom. More broadly, overestimating the size of the bottom face may represent a fundamental mechanism for social interactions, ensuring the deployment of attention to those closest to self.

Illusory faces are more likely to be perceived as male than female

Face pareidolia is the phenomenon of perceiving illusory faces in inanimate objects. Here we show that illusory faces engage social perception beyond the detection of a face: they have a perceived age, gender, and emotional expression. Additionally, we report a striking bias in gender perception, with many more illusory faces perceived as male than female. As illusory faces do not have a biological sex, this bias is significant in revealing an asymmetry in our face evaluation system given minimal information. Our result demonstrates that the visual features that are sufficient for face detection are not generally sufficient for the perception of female. Instead, the perception of a nonhuman face as female requires additional features beyond that required for face detection.

Despite our fluency in reading human faces, sometimes we mistakenly perceive illusory faces in objects, a phenomenon known as face pareidolia. Although illusory faces share some neural mechanisms with real faces, it is unknown to what degree pareidolia engages higher-level social perception beyond the detection of a face. In a series of large-scale behavioral experiments (n_total = 3,815 adults), we found that illusory faces in inanimate objects are readily perceived to have a specific emotional expression, age, and gender. Most strikingly, we observed a strong bias to perceive illusory faces as male rather than female. This male bias could not be explained by preexisting semantic or visual gender associations with the objects, or by visual features in the images. Rather, this robust bias in the perception of gender for illusory faces reveals a cognitive bias arising from a broadly tuned face evaluation system in which minimally viable face percepts are more likely to be perceived as male.

Infants' visual exploration strategies for adult and child faces

By the end of the first year of life, infants' discrimination abilities tune to frequently experienced face groups. Little is known about the exploration strategies adopted to efficiently discriminate frequent, familiar face types. The present eye-tracking study examined the distribution of visual fixations produced by 10-month-old and 4-month-old singletons while learning adult (i.e., familiar) and child (i.e., unfamiliar) White faces. Infants were tested in an infant-controlled visual habituation task, in which post-habituation preference measured successful discrimination. Results confirmed earlier evidence that, without sibling experience, 10-month-olds discriminate only among adult faces. Analyses of gaze movements during habituation showed that infants' fixations were centered in the upper part of the stimuli. The mouth was sampled longer in adult faces than in child faces, while the child eyes were sampled longer and more frequently than the adult eyes. At 10 months, but not at 4 months, global measures of scanning behavior on the whole face also varied according to face age, as the spatiotemporal distribution of scan paths showed larger within- and between-participants similarity for adult faces than for child faces. Results are discussed with reference to the perceptual narrowing literature, and the influence of age-appropriate developmental tasks on infants' face processing abilities.

Effects of interracial experience on the race preferences of infants

Over their first year of life, infants express visual preferences for own- versus other-race faces. This developmental transition has primarily been investigated in monoracial societies where infants have limited personal or societal contact with other races. We investigated whether previously reported visual preferences for race generalize to a multiracial society (i.e., Singapore). In addition, we investigated effects of caregiver race on visual preferences for race. In Experiment 1, race preferences were measured at 3, 6, and 9 months of age for own-race (Chinese) versus other-race (Indian) faces in infants with no regular interaction with Indian-race individuals. Singaporean infants displayed a significant visual preference for Indian-race faces at each age group. Furthermore, infants raised with other-race caregivers demonstrated an age-related increase in other-race visual preferences. The visual preferences of infants for other-race faces were predicted by the extent of other-race contact. In Experiment 2, we confirmed that an other-race visual preference was not exclusive to Indian faces in a sample of 6-month-old Singaporean Chinese infants who demonstrated a similar other-race visual preference for Caucasian faces over Chinese faces. Findings are discussed in terms of the influence of other-race contact on visual preferences for race in infants.

Logical word learning: The case of kinship

We examine the conceptual development of kinship through the lens of program induction. We present a computational model for the acquisition of kinship term concepts, resulting in the first computational model of kinship learning that is closely tied to developmental phenomena. We demonstrate that our model can learn several kinship systems of varying complexity using cross-linguistic data from English, Pukapuka, Turkish, and Yanomamö. More importantly, the behavioral patterns observed in children learning kinship terms, under-extension and over-generalization, fall out naturally from our learning model. We then conducted interviews to simulate realistic learning environments and demonstrate that the characteristic-to-defining shift is a consequence of our learning model in naturalistic contexts containing abstract and concrete features. We use model simulations to understand the influence of logical simplicity and children’s learning environment on the order of acquisition of kinship terms, providing novel predictions for the learning trajectories of these words. We conclude with a discussion of how this model framework generalizes beyond kinship terms, as well as a discussion of its limitations.

Cognitive-Based Interventions Break Gender Stereotypes in Kindergarten Children

Despite the growing recognition of gender equality worldwide, plausible strategies that reduce young children's gender stereotypes remain limited. Cognitive-based interventions have been widely used in school settings and have been suggested to play important roles in children's gender stereotyping and in their processing of counter-stereotypic information. We aimed to determine whether exposure to counter-stereotypical information could break gender stereotypes in kindergarten children. Fifty-four children (61-79 months old) from two public kindergarten classes in northern Taiwan participated in this study. One of the two classes was randomly selected as the experimental group (n = 28), and the other was the control group (n = 26). The experimental group consisted of a gender equality curriculum including script relationship training for two months, while the control group continued their regular curriculum. The picture classification task (PCT) was measured before and after the intervention to assess gender stereotypes. Before interventions, 87.50% of the children chose a gender stereotypic relationship, while 12.50% chose script/other relationships in PCT. After the interventions, the gender stereotypic relationship dropped to 73.22% in the experimental group. Children in the control group were more likely to maintain their gender stereotypic relationship choices in PCTs. Our findings suggest that cognitive-based interventions, such as a gender equality curriculum, have the potential to break gender stereotypes in kindergarten children.

Face Masks Bolsters the Characteristics From Looking at a Face Even When Facial Expressions Are Impaired

Face masks impact social interactions because emotion recognition is difficult due to face occlusion. However, is this enough to conclude that face masks negatively impact social interactions? We investigated the impact of face masks on invariant characteristics (sex, age), trait-like characteristics (trustworthiness, attractiveness, and approachability), and emotional expressions (happiness and excitability). Participants completed an online survey and rated masked and no-masked faces. The same face remained masked or no-masked throughout the survey. Results revealed that, when compared to no-masked faces, masked happy faces appeared less happy. Face masks did not negatively impact the ratings of other characteristics. Participants were better at judging the sex of masked faces. Masked faces also appeared younger, more trustworthy, more attractive, and more approachable. Therefore, face masks did not always result in unfavorable ratings. An additional post hoc modeling revealed that trustworthiness and attractiveness ratings for masked faces predicted the same trait ratings for no-masked faces. However, approachability ratings for no-masked faces predicted the same trait ratings for masked faces. This hinted that information from masked/no-masked faces, such as from the eye and eye region, could aid in the understanding of others during social interaction. Future directions were proposed to expand the research.

Small groups lead, big groups control: Perceptions of numerical group size, power, and status across development

Participants (N = 384 three- to ten-year-olds; 51% girls, 49% boys; 73% White, 18% multiracial/other, 5% Asian, and 3% Black; N = 610 adults) saw depictions of 20 individuals split into two social groups (1:19; 2:18; 5:15; or 8:12 per group) and selected which group was "in charge" (Experiment 1), "the leader" (Experiment 2), or likely to "get the stuff" (resources) in a conflict (Experiment 3). Whereas participants across ages predicted the larger group would "get the stuff," a tendency to view smaller groups as "in charge" and "the leader" strengthened with age and when the smaller group was rarer. These findings suggest the perceived relation between numerical group size and hierarchy is flexible and inform theory regarding the developmental trajectories of reasoning about power and status.