Looking Across Domains to Understand Infant Representation of Emotion

Child mask mandates for COVID-19: a systematic review

BACKGROUND

Mask mandates for children during the COVID-19 pandemic varied in different locations. A risk-benefit analysis of this intervention has not yet been performed. In this study, we performed a systematic review to assess research on the effectiveness of mask wearing in children.

METHODS

We performed database searches up to February 2023. The studies were screened by title and abstract, and included studies were further screened as full-text references. A risk-of-bias analysis was performed by two independent reviewers and adjudicated by a third reviewer.

RESULTS

We screened 597 studies and included 22 in the final analysis. There were no randomised controlled trials in children assessing the benefits of mask wearing to reduce SARS-CoV-2 infection or transmission. The six observational studies reporting an association between child masking and lower infection rate or antibody seropositivity had critical (n=5) or serious (n=1) risk of bias; all six were potentially confounded by important differences between masked and unmasked groups and two were shown to have non-significant results when reanalysed. Sixteen other observational studies found no association between mask wearing and infection or transmission.

CONCLUSIONS

Real-world effectiveness of child mask mandates against SARS-CoV-2 transmission or infection has not been demonstrated with high-quality evidence. The current body of scientific data does not support masking children for protection against COVID-19.

Should perception of emotions be classified according to threat detection rather than emotional valence? An updated meta-analysis for a whole-brain atlas of emotional faces processing

BACKGROUND

Human navigation of social interactions relies on the processing of emotion on faces. This meta-analysis aimed to produce an updated brain atlas of emotional face processing from whole-brain studies based on a single emotional face-viewing paradigm (PROSPERO CRD42022251548).

METHODS

We conducted a systematic literature search of Embase, MEDLINE and PsycINFO from May 2008 to October 2021. We used seed-based d mapping with permutation of subject images to conduct a quantitative meta-analysis of functional neuroimaging contrasts between emotional (e.g., angry, happy) and neutral faces. We conducted agglomerative hierarchical clustering of meta-analytic map contrasts of emotional faces relative to neutral faces. We investigated lateralization of emotional face processing.

RESULTS

From 5549 studies identified, 55 data sets (1489 healthy participants) met our inclusion criteria. Relative to neutral faces, we found extensive activation clusters by fearful faces in the right inferior temporal gyrus, right fusiform area, left putamen and amygdala, right parahippocampalgyrus and cerebellum; we found smaller activation clusters by angry faces in the right cerebellum and right middle temporal gyrus (MTG) and by disgusted faces in the left MTG. Happy and sad faces did not reach statistical significance. Clustering analyses showed similar activation patterns of fearful and angry faces; activation patterns of happy and sad faces showed the least correlation with other emotional faces. Emotional face processing was predominantly left-lateralized in the amygdala and anterior insula, and right-lateralized in the ventromedial prefrontal cortex.

LIMITATIONS

Reliance on discretized effect sizes based on peak coordinate location instead of statistical brain maps, and the varying level of statistical threshold reporting from original studies, could lead to underdetection of smaller clusters of activation.

CONCLUSION

Processing of emotional faces appeared to be oriented toward identifying threats on faces, from highest (i.e., angry or fearful faces) to lowest level (i.e., happy or sad faces), with a more complex lateralization pattern than previously theorized. Emotional faces may be processed in latent grouping but organized by threat content rather than emotional valence.

Infants aren't biased toward fearful faces

Grossmann's argument for the "fearful ape hypothesis" rests on an incomplete review of infant responses to emotional faces. An alternate interpretation of the literature argues the opposite, that an early preference for happy faces predicts cooperative learning. Questions remain as to whether infants can interpret affect from faces, limiting the conclusion that any "fear bias" means the infant is fearful.

A neural marker of rapid discrimination of facial expression in 3.5- and 7-month-old infants

Infants’ ability to discriminate facial expressions has been widely explored, but little is known about the rapid and automatic ability to discriminate a given expression against many others in a single experiment. Here we investigated the development of facial expression discrimination in infancy with fast periodic visual stimulation coupled with scalp electroencephalography (EEG). EEG was recorded in eighteen 3.5- and eighteen 7-month-old infants presented with a female face expressing disgust, happiness, or a neutral emotion (in different stimulation sequences) at a base stimulation frequency of 6 Hz. Pictures of the same individual expressing other emotions (either anger, disgust, fear, happiness, sadness, or neutrality, randomly and excluding the expression presented at the base frequency) were introduced every six stimuli (at 1 Hz). Frequency-domain analysis revealed an objective (i.e., at the predefined 1-Hz frequency and harmonics) expression-change brain response in both 3.5- and 7-month-olds, indicating the visual discrimination of various expressions from disgust, happiness and neutrality from these early ages. At 3.5 months, the responses to the discrimination from disgust and happiness expressions were located mainly on medial occipital sites, whereas a more lateral topography was found for the response to the discrimination from neutrality, suggesting that expression discrimination from an emotionally neutral face relies on distinct visual cues than discrimination from a disgust or happy face. Finally, expression discrimination from happiness was associated with a reduced activity over posterior areas and an additional response over central frontal scalp regions at 7 months as compared to 3.5 months. This result suggests developmental changes in the processing of happiness expressions as compared to negative/neutral ones within this age range.

Linguistic and developmental influences on superordinate facial configuration categorization in infancy

Humans perceive emotions in terms of categories, such as "happiness," "sadness," and "anger." To learn these complex conceptual emotion categories, humans must first be able to perceive regularities in expressive behaviors (e.g., facial configurations) across individuals. Recent research suggests that infants spontaneously form "basic-level" categories of facial configurations (e.g., happy vs. fear), but not "superordinate" categories of facial configurations (e.g., positive vs. negative). The current studies further explore how infant age and language impact superordinate categorization of facial configurations associated with different negative emotions. Across all experiments, infants were habituated to one person displaying facial configurations associated with anger and disgust. While 10-month-olds formed a category of person identity (Experiment 1), 14-month-olds formed a category that included negative facial configurations displayed by the same person (Experiment 2). However, neither age formed the hypothesized superordinate category of negative valence. When a verbal label ("toma") was added to each of the habituation events (Experiment 3), 10-month-olds formed a category similar to 14-month-olds in Experiment 2. These findings intersect a larger conversation about the nature and development of children's emotion categories and highlight the importance of considering developmental processes, such as language learning and attentional/memory development, in the design and interpretation of infant categorization studies.

Infants show pupil dilatory responses to happy and angry facial expressions

Facial expressions are one way in which infants and adults communicate emotion. Infants scan expressions similarly to adults, yet it remains unclear whether they are receptive to the affective information they convey. The current study investigates 6-, 9- and 12-month infants' (N = 146) pupillary responses to the six "basic" emotional expressions (happy, sad, surprise, fear, anger, and disgust). To do this we use dynamic stimuli and gaze-contingent eye-tracking to simulate brief interactive exchanges, alongside a static control condition. Infants' arousal responses were stronger for dynamic compared to static stimuli. And for dynamic stimuli we found that, compared to neutral, infants showed dilatory responses for happy and angry expressions only. Although previous work has shown infants can discriminate perceptually between facial expressions, our data suggest that sensitivity to the affective content of all six basic emotional expressions may not fully emerge until later in ontogeny.

The encoding of race during face processing, an event-related potential study

It is well known that adults spontaneously classify people into social categories and this categorization in turn guides their cognition and behavior. A wealth of research has examined how people perceive race and investigated the effect of race on social behavior. But what about race encoding? Although considerable behavioral research has investigated the encoding of race, that is, the social categorization by race, the neural underpinning of it is largely underexplored. To investigate the time course of race encoding, the current study employed a modified category verification task and a multivariate analyzing approach. We found that racial information became decodable from event-related potential topographies as early as about 200 ms after stimulus onset. At this stage, the brain can differentiate different races in a task-relevant manner. Nonetheless, it is not until 100 ms later that racial information is encoded in a socially relevant manner (own- versus other-race). Importantly, perceptual differentiation not only occurs before the encoding of the race but actually influences it: the faces that are more easily perceptually categorized are actually encoded more readily. Together, we posit that the detection and the encoding of race are decoupled although they are not completely independent. Our results provide powerful constraints toward the theory-building of race.

The Interplay Between Affective Processing and Sense of Agency During Action Regulation: A Review

Sense of agency is the feeling of being in control of one's actions and their perceivable effects. Most previous research identified cognitive or sensory determinants of agency experience. However, it has been proposed that sense of agency is also bound to the processing of affective information. For example, during goal-directed actions or instrumental learning we often rely on positive feedback (e.g., rewards) or negative feedback (e.g., error messages) to determine our level of control over the current task. Nevertheless, we still lack a scientific model which adequately explains the relation between affective processing and sense of agency. In this article, we review current empirical findings on how affective information modulates agency experience, and, conversely, how sense of agency changes the processing of affective action outcomes. Furthermore, we discuss in how far agency-related changes in affective processing might influence the ability to enact cognitive control and action regulation during goal-directed behavior. A preliminary model is presented for describing the interplay between sense of agency, affective processing, and action regulation. We propose that affective processing could play a role in mediating the influence between subjective sense of agency and the objective ability to regulate one's behavior. Thus, determining the interrelation between affective processing and sense of agency will help us to understand the potential mechanistic basis of agency experience, as well as its functional significance for goal-directed behavior.

Going virtual in the early years: 30-month-old toddlers recognize commonly used emojis

People nowadays do not only display facial expressions in face to face communication but also in on-line communication using graphical symbols named emojis. The present study explored 30-month-old toddlers' ability to recognize emojis that represented six basic human emotions. In the study, 38 toddlers first saw scenarios that elicited different emotions in an actor and were asked to visually identify the matching emoji in the presence of a distractor. Eye-tracking results showed that toddlers could correctly identify the emoji that represented the emotion in each scenario. Toddlers then heard different emotion words and were again found to be able to identify the matching emoji. These findings provide preliminary evidence that the ability to recognize and understand the emotional value of emotion symbols in the virtual world emerges early in development.

The Development of Emotion Reasoning in Infancy and Early Childhood

Historically, research characterizing the development of emotion recognition has focused on identifying specific skills and the age periods, or milestones, at which these abilities emerge. However, advances in emotion research raise questions about whether this conceptualization accurately reflects how children learn about, understand, and respond to others’ emotions in everyday life. In this review, we propose a developmental framework for the emergence of emotion reasoning—that is, how children develop the ability to make reasonably accurate inferences and predictions about the emotion states of other people. We describe how this framework holds promise for building upon extant research. Our review suggests that use of the term emotion recognition can be misleading and imprecise, with the developmental processes of interest better characterized by the term emotion reasoning. We also highlight how the age at which children succeed on many tasks reflects myriad developmental processes. This new framing of emotional development can open new lines of inquiry about how humans learn to navigate their social worlds.

Dynamic Advances in Emotion Processing: Differential Attention towards the Critical Features of Dynamic Emotional Expressions in 7-Month-Old Infants

Infants' visual processing of emotion undergoes significant development across the first year of life, yet our knowledge regarding the mechanisms underlying these advances is limited. Additionally, infant emotion processing is commonly examined using static faces, which do not accurately depict real-world emotional displays. The goal of this study was to characterize 7-month-olds' visual scanning strategies when passively viewing dynamic emotional expressions to examine whether infants modify their scanning patterns depending on the emotion. Eye-tracking measures revealed differential attention towards the critical features (eyes, mouth) of expressions. The eyes captured the greatest attention for angry and neutral faces, and the mouth captured the greatest attention for happy faces. A time-course analysis further elucidated at what point during the trial differential scanning patterns emerged. The current results suggest that 7-month-olds are sensitive to the critical features of emotional expressions and scan them differently depending on the emotion. The scanning patterns presented in this study may serve as a link to understanding how infants begin to differentiate between expressions in the context of emotion recognition.

Comparing race, gender, age, and career categories in recognizing and grouping tasks

The purpose of our research was to compare how participants weighed age, gender, race, and career categories in recognizing and grouping tasks. In Study 1, we used a category recognition task to compare participants' speeds in recognizing information from different categories. The results showed that participants recognized the gender information most quickly, followed by career, race, and age information. In Study 2, a categorization task was used to compare participants' category preferences. The results showed that the career category had the greatest weight, and the gender category had the lowest weight. Two targets who had different career identities were more possible considered as belonging to different groups than two targets with different gender, race or age identities. Our results have implications in understanding the weight of different categories, with gender and career category are the most important category that affects perception and evaluation.

Superordinate categorization of negative facial expressions in infancy: The influence of labels

Accurate perception of emotional (facial) expressions is an essential social skill. It is currently debated whether emotion categorization in infancy emerges in a "broad-to-narrow" pattern and the degree to which language influences this process. We used an habituation paradigm to explore (a) whether 14- and 18-month-old infants perceive different facial expressions (anger, sad, disgust) as belonging to a superordinate category of negative valence and (b) how verbal labels influence emotion category formation. Results indicated that infants did not spontaneously form a superordinate category of negative valence (Experiments 1 and 3). However, when a novel label ("toma") was added to each event during habituation trials (Experiments 2 and 4), infants formed this superordinate valance category when habituated to disgust and sad expressions (but not when habituated to anger and sadness). These labeling effects were obtained with two stimuli sets (Radboud Face Database and NimStim), even when controlling for the presence of teeth in the expressions. The results indicate that infants, at 14 and 18 months of age, show limited superordinate categorization based on the valence of different negative facial expressions. Specifically, infants only form this abstract emotion category when labels were provided, and the labeling effect depends on which emotions are presented during habituation. These findings have important implications for developmental theories of emotion. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Do Preverbal Infants Understand Discrete Facial Expressions of Emotion?

An ongoing debate in affective science concerns whether certain discrete, “basic” emotions have evolutionarily based signals (facial expressions) that are easily, universally, and (perhaps) innately identified. Studies with preverbal infants (younger than 24 months) have the potential to shed light on this debate. This review summarizes what is known about preverbal infants’ understanding of discrete emotional facial expressions. Overall, while many studies suggest that preverbal infants differentiate positive and negative facial expressions, few studies have tested whether infants understand discrete emotions (e.g., anger vs. disgust). Moreover, results vary greatly based on methodological factors. This review also (a) discusses how language may influence the development of emotion understanding, and (b) proposes a new developmental hypothesis for infants’ discrete emotion understanding.

Face Processing in Infancy and Beyond: The Case of Social Categories

Prior reviews of infant face processing have emphasized how infants respond to faces in general. This review highlights how infants come to respond differentially to social categories of faces based on differential experience, with a focus on race and gender. We examine six different behaviors: preference, recognition, scanning, category formation, association with emotion, and selective learning. Although some aspects of infant responding to face race and gender may be accounted for by traditional models of perceptual development, other aspects suggest the need for a broader model that links perceptual development with social and emotional development. We also consider how responding to face race and gender in infancy may presage responding to these categories beyond infancy and discuss how social biases favoring own-race and female faces are formed.

The eyes know it: Toddlers' visual scanning of sad faces is predicted by their theory of mind skills

The current research explored toddlers' gaze fixation during a scene showing a person expressing sadness after a ball is stolen from her. The relation between the duration of gaze fixation on different parts of the person's sad face (e.g., eyes, mouth) and theory of mind skills was examined. Eye tracking data indicated that before the actor experienced the negative event, toddlers divided their fixation equally between the actor's happy face and other distracting objects, but looked longer at the face after the ball was stolen and she expressed sadness. The strongest predictor of increased focus on the sad face versus other elements of the scene was toddlers' ability to predict others' emotional reactions when outcomes fulfilled (happiness) or failed to fulfill (sadness) desires, whereas toddlers' visual perspective-taking skills predicted their more specific focusing on the actor's eyes and, for boys only, mouth. Furthermore, gender differences emerged in toddlers' fixation on parts of the scene. Taken together, these findings suggest that top-down processes are involved in the scanning of emotional facial expressions in toddlers.

Implicit preference for human trustworthy faces in macaque monkeys

It has been shown that human judgements of trustworthiness are based on subtle processing of specific facial features. However, it is not known if this ability is a specifically human function, or whether it is shared among primates. Here we report that macaque monkeys (Macaca Mulatta and Macaca Fascicularis), like humans, display a preferential attention to trustworthiness-associated facial cues in computer-generated human faces. Monkeys looked significantly longer at faces categorized a priori as trustworthy compared to untrustworthy. In addition, spatial sequential analysis of monkeys’ initial saccades revealed an upward shift with attention moving to the eye region for trustworthy faces while no change was observed for the untrustworthy ones. Finally, we found significant correlations between facial width-to-height ratio– a morphometric feature that predicts trustworthiness’ judgments in humans – and looking time in both species. These findings suggest the presence of common mechanisms among primates for first impression of trustworthiness.

Humans infer the trustworthiness of others based on subtle facial features such as the facial width-to-height ratio, but it is not known whether other primates are sensitive to these cues. Here, the authors show that macaque monkeys prefer to look at human faces which appear trustworthy to humans.

Fearful but not happy expressions boost face detection in human infants

Human adults show an attentional bias towards fearful faces, an adaptive behaviour that relies on amygdala function. This attentional bias emerges in infancy between 5 and 7 months, but the underlying developmental mechanism is unknown. To examine possible precursors, we investigated whether 3.5-, 6- and 12-month-old infants show facilitated detection of fearful faces in noise, compared to happy faces. Happy or fearful faces, mixed with noise, were presented to infants (N = 192), paired with pure noise. We applied multivariate pattern analyses to several measures of infant looking behaviour to derive a criterion-free, continuous measure of face detection evidence in each trial. Analyses of the resulting psychometric curves supported the hypothesis of a detection advantage for fearful faces compared to happy faces, from 3.5 months of age and across all age groups. Overall, our data show a readiness to detect fearful faces (compared to happy faces) in younger infants that developmentally precedes the previously documented attentional bias to fearful faces in older infants and adults.

Face Experience and the Attentional Bias for Fearful Expressions in 6- and 9-Month-Old Infants

Infants demonstrate an attentional bias toward fearful facial expressions that emerges in the first year of life. The current study investigated whether this attentional bias is influenced by experience with particular face types. Six-month-old (n = 33) and 9-month-old (n = 31) Caucasian infants' spontaneous preference for fearful facial expressions when expressed by own-race (Caucasian) or other-race (East Asian) faces was examined. Six-month-old infants showed a preference for fearful expressions when expressed by own-race faces, but not when expressed by other-race faces. Nine-month-old infants showed a preference for fearful expressions when expressed by both own-race faces and other-race faces. These results suggest that how infants deploy their attention to different emotional expressions is shaped by experience: Attentional biases might initially be restricted to faces with which infants have the most experience, and later be extended to faces with which they have less experience.

Early preschool environments and gender: Effects of gender pedagogy in Sweden

To test how early social environments affect children's consideration of gender, 3- to 6-year-old children (N=80) enrolled in gender-neutral or typical preschool programs in the central district of a large Swedish city completed measures designed to assess their gender-based social preferences, stereotypes, and automatic encoding. Compared with children in typical preschools, a greater proportion of children in the gender-neutral school were interested in playing with unfamiliar other-gender children. In addition, children attending the gender-neutral preschool scored lower on a gender stereotyping measure than children attending typical preschools. Children at the gender-neutral school, however, were not less likely to automatically encode others' gender. The findings suggest that gender-neutral pedagogy has moderate effects on how children think and feel about people of different genders but might not affect children's tendency to spontaneously notice gender.

Recognizing facial expressions of emotion in infancy: A replication and extension

Infants may recognize facial expressions of emotion more readily when familiar faces express the emotions. Studies 1 and 2 investigated whether familiarity influences two metrics of emotion processing: Categorization and spontaneous preference. In Study 1 (n = 32), we replicated previous findings showing an asymmetrical pattern of categorization of happy and fearful faces in 6.5-month-old infants, and extended these findings by demonstrating that infants' categorization did not differ when emotions were expressed by familiar (i.e., caregiver) faces. In Study 2 (n = 34), we replicated the spontaneous preference for fearful over happy expressions in 6.5-month-old infants, and extended these findings by demonstrating that the spontaneous preference for fear was also present for familiar faces. Thus, infants' performance on two metrics of emotion processing did not differ depending on face familiarity.

Integrated Emotion Processing in Infancy: Matching of Faces and Bodies

Accurate assessment of emotion requires the coordination of information from different sources such as faces, bodies, and voices. Adults readily integrate facial and bodily emotions. However, not much is known about the developmental origin of this capacity. Using a familiarization paired-comparison procedure, 6.5-month-olds in the current experiments were familiarized to happy, angry, or sad emotions in faces or bodies and tested with the opposite image type portraying the familiar emotion paired with a novel emotion. Infants looked longer at the familiar emotion across faces and bodies (except when familiarized to angry images and tested on the happy/angry contrast). This matching occurred not only for emotions from different affective categories (happy, angry) but also within the negative affective category (angry, sad). Thus, 6.5-month-olds, like adults, integrate emotions from bodies and faces in a fairly sophisticated manner, suggesting rapid development of emotion processing early in life.

Further evidence of early development of attention to dynamic facial emotions: Reply to Grossmann and Jessen

Adults exhibit enhanced attention to negative emotions like fear, which is thought to be an adaptive reaction to emotional information. Previous research, mostly conducted with static faces, suggests that infants exhibit an attentional bias toward fearful faces only at around 7months of age. In a recent study (Journal of Experimental Child Psychology, 2016, Vol. 147, pp. 100-110), we found that 5-month-olds also exhibit heightened attention to fear when tested with dynamic face videos. This indication of an earlier development of an attention bias to fear raises questions about developmental mechanisms that have been proposed to underlie this function. However, Grossmann and Jessen (Journal of Experimental Child Psychology, 2016, Vol. 153, pp. 149-154) argued that this result may have been due to differences in the amount of movement in the videos rather than a response to emotional information. To examine this possibility, we tested a new sample of 5-month-olds exactly as in the original study (Heck, Hock, White, Jubran, & Bhatt, 2016) but with inverted faces. We found that the fear bias seen in our study was no longer apparent with inverted faces. Therefore, it is likely that infants' enhanced attention to fear in our study was indeed a response to emotions rather than a reaction to arbitrary low-level stimulus features. This finding indicates enhanced attention to fear at 5months and underscores the need to find mechanisms that engender the development of emotion knowledge early in life.

The development of attention to dynamic facial emotions

Appropriate processing of emotions is paramount for successful social functioning. Adults' enhanced attention to negative emotions such as fear is thought to be a critical aspect of this adaptive functioning. Prior studies indicate that increased attention to fear relative to positive or neutral emotions begins at around 7months of age, and it has been suggested that this negativity bias is related to self-locomotion. However, these studies mostly used static faces, potentially limiting information available to the infants. In the current study, 3.5-month-olds (n=24) and 5-month-olds (n=24) were exposed to dynamic faces expressing fear, happy, or neutral emotions and a distracting peripheral checkerboard. The 5-month-olds looked proportionally longer at the face compared with the checkerboard when the face was fearful than when it was happy or neutral. Conversely, the 3.5-month-olds did not differentiate their attention as a function of emotion. These results indicate that the onset of enhanced attention to fear occurs between 3.5 and 5months of age. This finding raises questions about the developmental mechanisms that drive attentional bias given that the idea of the onset of self-locomotion being a catalyst for the development of negativity bias might no longer hold.

Building emotion categories: Children use a process of elimination when they encounter novel expressions

Recent research has indicated that language provides an important contribution to adults' conceptions of emotional expressions and their associated categories, but how language influences children's expression category acquisition has yet to be explored. Across two studies, we provide evidence that when preschoolers (2-4years) encounter a novel label, they use a process of elimination to match it with its expected expression. Children successfully used a process of elimination to match a single expression to one of several labels (Study 1) and to match a single label to one of several expressions (Study 2). These data highlight one possible mechanism that children may use to learn about the expressions they encounter and may shed light on the ways in which children's expression categories are constructed.

Heterogeneity in perceptual category learning by high functioning children with autism spectrum disorder

Previous research suggests that high functioning (HF) children with autism spectrum disorder (ASD) sometimes have problems learning categories, but often appear to perform normally in categorization tasks. The deficits that individuals with ASD show when learning categories have been attributed to executive dysfunction, general deficits in implicit learning, atypical cognitive strategies, or abnormal perceptual biases and abilities. Several of these psychological explanations for category learning deficits have been associated with neural abnormalities such as cortical underconnectivity. The present study evaluated how well existing neurally based theories account for atypical perceptual category learning shown by HF children with ASD across multiple category learning tasks involving novel, abstract shapes. Consistent with earlier results, children’s performances revealed two distinct patterns of learning and generalization associated with ASD: one was indistinguishable from performance in typically developing children; the other revealed dramatic impairments. These two patterns were evident regardless of training regimen or stimulus set. Surprisingly, some children with ASD showed both patterns. Simulations of perceptual category learning could account for the two observed patterns in terms of differences in neural plasticity. However, no current psychological or neural theory adequately explains why a child with ASD might show such large fluctuations in category learning ability across training conditions or stimulus sets.

Face Gender Influences the Looking Preference for Smiling Expressions in 3.5-Month-Old Human Infants

Young infants are typically thought to prefer looking at smiling expressions. Although some accounts suggest that the preference is automatic and universal, we hypothesized that it is not rigid and may be influenced by other face dimensions, most notably the face's gender. Infants are sensitive to the gender of faces; for example, 3-month-olds raised by female caregivers typically prefer female over male faces. We presented neutral versus smiling pairs of faces from the same female or male individuals to 3.5-month-old infants (n = 25), controlling for low-level cues. Infants looked longer to the smiling face when faces were female but longer to the neutral face when faces were male, i.e., there was an effect of face gender on the looking preference for smiling. The results indicate that a preference for smiling in 3.5-month-olds is limited to female faces, possibly reflective of differential experience with male and female faces.

Affective matching of odors and facial expressions in infants: shifting patterns between 3 and 7 months

Recognition of emotional facial expressions is a crucial skill for adaptive behavior. Past research suggests that at 5 to 7 months of age, infants look longer to an unfamiliar dynamic angry/happy face which emotionally matches a vocal expression. This suggests that they can match stimulations of distinct modalities on their emotional content. In the present study, olfaction-vision matching abilities were assessed across different age groups (3, 5 and 7 months) using dynamic expressive faces (happy vs. disgusted) and distinct hedonic odor contexts (pleasant, unpleasant and control) in a visual-preference paradigm. At all ages the infants were biased toward the disgust faces. This visual bias reversed into a bias for smiling faces in the context of the pleasant odor context in the 3-month-old infants. In infants aged 5 and 7 months, no effect of the odor context appeared in the present conditions. This study highlights the role of the olfactory context in the modulation of visual behavior toward expressive faces in infants. The influence of olfaction took the form of a contingency effect in 3-month-old infants, but later evolved to vanish or to take another form that could not be evidenced in the present study.

"Aren't you supposed to be sad?" Infants do not treat a stoic person as an unreliable emoter

The current study examined how 18-month-old infants react to a "stoic" person, that is, someone who displays a neutral facial expression following negative experiences. Infants first watched a series of events during which an actor had an object stolen from her. In one condition, infants then saw the actor display sadness, while she remained neutral in the other condition. Then, all infants interacted with the actor in emotional referencing, instrumental helping, empathic helping, and imitation tasks. Results revealed that during the exposure phase, infants in both groups looked an equal amount of time at the scene and engaged in similar levels of hypothesis testing. However, infants in the sad group expressed more concern toward the actor than those in the neutral group. No differences were found between the two groups on the interactive tasks. This conservative test of selective learning and altruism shows that, at 18 months, infants are sensitive to the valence of emotional expressions following negative events but also consider an actor's neutral expression just as appropriate as a sad expression following a negative experience. These findings represent an important contribution to research on the emergence of selective trust during infancy.

Young children's automatic encoding of social categories

The present research investigated young children's automatic encoding of two social categories that are highly relevant to adults: gender and race. Three- to 6-year-old participants learned facts about unfamiliar target children who varied in either gender or race and were asked to remember which facts went with which targets. When participants made mistakes, they were more likely to confuse targets of the same gender than targets of different genders, but they were equally likely to confuse targets within and across racial groups. However, a social preference measure indicated that participants were sensitive to both gender and race information. Participants with more racial diversity in their social environments were more likely to encode race, but did not have stronger racial preferences. These findings provide evidence that young children do not automatically encode all perceptible features of others. Further, gender may be a more fundamental social category than race.

Doing It With Feeling: The Emotion in Early Socioemotional Development

Carroll Izard’s theoretical and research contributions to the study of early socioemotional development are profiled. His studies of early emotional expression and the formulations of differential emotions theory have stimulated contemporary inquiry into the organization of early emotional life, the developmental processes by which distinct feelings and facial expressions become progressively concordant, and how the emotional expressions of others become imbued with emotion meaning. His work on emotion, attachment, and emotion–cognition relations has contributed to contemporary study of the emotional bases of attachment organization and the development of the internal working models associated with attachment security. Because of Izard’s contributions, developmental emotions research is theoretically richer, and emotion has a more central place in our understanding of development and motivation.

Color preferences in infants and adults are different

Adults commonly prefer blues most and greenish yellows least, but these hue preferences interact with lightness and saturation (e.g., dark yellow is particularly disliked: Palmer & Schloss (Proceedings of the National Academy of Sciences 107:8877-8882, 2010)). Here, we tested for a similar hue-by-lightness interaction in infant looking preferences, to determine whether adult preferences are evident early in life. We measured looking times for both infants and adults in the same paired-comparison task using all possible pairs of eight colors: four hues (red/yellow/green/blue) at two lightness levels (dark/light). The adult looking data were strikingly similar to other adults' explicit preference responses, indicating for the first time that adults look longer at colors that they like. Infants showed a significant hue-by-lightness interaction, but it was quite different from the adult pattern. In particular, infants had a stronger looking preference for dark yellow and a weaker preference for light blue than did adults. The findings are discussed in relation to theories on the origins of color preference.

On the Links Among Face Processing, Language Processing, and Narrowing During Development

From the beginning of life, face and language processing are crucial for establishing social communication. Studies on the development of systems for processing faces and language have yielded such similarities as perceptual narrowing across both domains. In this article, we review several functions of human communication, and then describe how the tools used to accomplish those functions are modified by perceptual narrowing. We conclude that narrowing is common to all forms of social communication. We argue that during evolution, social communication engaged different perceptual and cognitive systems-face, facial expression, gesture, vocalization, sound, and oral language-that emerged at different times. These systems are interactive and linked to some extent. In this framework, narrowing can be viewed as a way infants adapt to their native social group.

Cry babies and pollyannas: Infants can detect unjustified emotional reactions

Infants are attuned to emotional facial and vocal expressions, reacting most prominently when they are exposed to negative expressions. However, it remains unknown if infants can detect whether a person's emotions are justifiable given a particular context. The focus of the current paper was to examine whether infants react the same way to unjustified (e.g., distress following a positive experience) and justified (e.g., distress following a negative experience) emotional reactions. Infants aged 15 and 18 months were shown an actor experiencing negative and positive experiences, with one group exposed to an actor whose emotional reactions were consistently unjustified (i.e., did not match the event), while the other saw an actor whose emotional reactions were justified (i.e., always matched the event). Infants' looking times and empathic reactions were examined. Only 18-month-olds detected the mismatching facial expressions: those in the unjustified group showed more hypothesis testing (i.e., checking) across events than the justified group. Older infants in the justified group also showed more concerned reactions to negative expressions than those in the unjustified group. The present findings indicate that infants implicitly understand how the emotional valence of experiences is linked to subsequent emotional expressions.