Preverbal infants identify emotional reactions that are incongruent with goal outcomes

Effects of conflicting emotional cues on toddlers' emotion perception

The communication of emotion is dynamic and occurs across multiple channels, such as facial expression and tone of voice. When cues are in conflict, interpreting emotion can become challenging. Here, we examined the effects of incongruent emotional cues on toddlers' interpretation of emotions. We presented 33 children (22-26 months, Mage = 23.8 months, 15 female) with side-by-side images of faces along with sentences spoken in a tone of voice that conflicted with semantic content. One of the two faces matched the emotional tone of the audio, whereas the other matched the semantic content. For both congruent and incongruent trials, toddlers showed no overall looking preference to either type of face stimuli. However, during the second exposure to the sentences of incongruent trials, older children tended to look longer to the face matching semantic content when listening to happy vs. angry content. Results inform our understanding of the early development of complex emotion understanding.

Choosing Among Undesirable Options: Children Consider Desirability of Available Choices in Evaluation of Socially Mindful Actions

Previous studies show that adults and children evaluate the act of leaving a choice for others as prosocial, and have termed such actions as socially mindful actions. The current study investigates how the desirability of the available options (i.e., whether the available options are desirable or not) may influence adults' and children's evaluation of socially mindful actions. Children (N = 120, 4- to 6-year-olds) and adults (N = 124) were asked to evaluate characters selecting items for themselves from a set of three items-two identical items and one unique item-in a way that either leaves a choice (two diverse items) or leaves no choice (two identical items) for the next person (i.e., the beneficiary). We manipulated whether the available options were either desirable or undesirable (i.e., damaged). We found that adults' and 6-year-olds' evaluation of socially mindful actions is moderated by the desirability of the options. Although they evaluate the act of leaving a choice for others as nicer than the act of leaving no choice both when the choosing options are desirable and when they are undesirable, the discrepancy in the evaluation becomes significantly smaller when the choosing options are undesirable. We also found that inference of the beneficiary's feeling underlies social evaluation of the actor leaving a choice (or not). These findings suggest that children consider both the diversity of options left and the desirability of the available options in understanding and evaluating socially mindful acts.

Infants expect friends, but not rivals, to be happy for each other when they succeed

A friend telling you good news earns them a smile while witnessing a rival win an award may make you wrinkle your nose. Emotions arise not just from people's own circumstances, but also from the experiences of friends and rivals. Across three moderated, online looking time studies, we asked if human infants hold expectations about others' vicarious emotions and if they expect those emotions to be guided by social relationships. Ten- and 11-month-old infants (N = 154) expected an observer to be happy rather than sad when the observer watched a friend successfully jump over a wall; infants looked longer at the sad response compared to the happy response. In contrast, infants did not expect the observer to be happy when the friend failed, nor when a different, rival jumper succeeded; infants' looking times to the two emotion responses in these conditions were not reliably different. These results suggest that infants are able to integrate knowledge across social contexts to guide expectations about vicarious emotional responses. Here infants connected an understanding of agents' goals and their outcomes with knowledge of social relationships to infer an emotion response. Biased concern for friends but not adversaries is not just a descriptive feature of human relationships, but an expectation about the social world present from early in development. Further, the successful integration of these information types welcomes the possibility that infants can jointly reason about goals, emotions, and social relationships under an intuitive theory of psychology. RESEARCH HIGHLIGHTS: 11-month-old infants use knowledge of relationships to make inferences about others' vicarious emotions. In Experiment 1 infants expected an observer to respond happily to a friend's success but not their failure. Experiments 2 and 3 varied the relationship between the observer and actor and found that infants' expectation of vicarious happiness is strongest for positive relationships and absent for negative relationships. The results may reflect an intuitive psychology in which infants expect friends to adopt concern for one another's goals and to thus experience one another's successes as rewarding.

Reading minds or reading scripts? De-intellectualising theory of mind

Understanding the origins of human social cognition is a central challenge in contemporary science. In recent decades, the idea of a 'Theory of Mind' (ToM) has emerged as the most popular way of explaining unique features of human social cognition. This default view has been progressively undermined by research on 'implicit' ToM, which suggests that relevant precursor abilities may already be present in preverbal human infants and great apes. However, this area of research suffers from conceptual difficulties and empirical limitations, including explanatory circularity, over-intellectualisation, and inconsistent empirical replication. Our article breaks new ground by adapting 'script theory' for application to both linguistic and non-linguistic agents. It thereby provides a new theoretical framework able to resolve the aforementioned issues, generate novel predictions, and provide a plausible account of how individuals make sense of the behaviour of others. Script theory is based on the premise that pre-verbal infants and great apes are capable of basic forms of agency-detection and non-mentalistic goal understanding, allowing individuals to form event-schemata that are then used to make sense of the behaviour of others. We show how script theory circumvents fundamental problems created by ToM-based frameworks, explains patterns of inconsistent replication, and offers important novel predictions regarding how humans and other animals understand and predict the behaviour of others.

Calculated Feelings: How Children Use Probability to Infer Emotions

Developing the ability to accurately infer others' emotions is crucial for children's cognitive development. Here, we offer a new theoretical perspective on how children develop this ability. We first review recent work showing that with age, children increasingly use probability to infer emotions. We discuss how these findings do not fit with prominent accounts of how children understand emotions, namely the script account and the theory of mind account. We then outline a theory of how probability allows children to infer others' emotions. Specifically, we suggest that probability provides children with information about how much weight to put on alternative outcomes, allowing them to infer emotions by comparing outcomes to counterfactual alternatives.

Children's Reasoning About Empathy and Social Relationships

Across the lifespan, empathic and counter-empathic emotions are shaped by social relationships. Here we test the hypothesis that this connection is encoded in children's intuitive theory of psychology, allowing them to predict when others will feel empathy versus counter-empathy and to use vicarious emotion information to infer relationships. We asked 4- to 7-year-old children (N = 79) to make emotion predictions or relationship inferences in response to stories featuring two characters, an experiencer and an observer, and either a positive or negative outcome for the experiencer. In the context of positive outcomes, we found that children engaged in robust joint reasoning about relationships and vicarious emotions. When given information about the characters' relationship, children predicted empathy from a friendly observer and counter-empathy from a rival observer. When given information about the observer's response to the experiencer, children inferred positive and negative relationships from empathic and counter-empathic responses, respectively. In the context of negative outcomes, children predicted that both friendly and rival observers would feel empathy toward the experiencer, but they still used information about empathic versus counter-empathic responses to infer relationship status. Our results suggest that young children in the US have a blanket expectation of empathic concern in response to negative outcomes, but otherwise expect and infer that vicarious emotions are connected to social relationships. Future research should investigate if children use this understanding to select social partners, evaluate their own relationships, or decide when to express empathy toward others.

Early antecedents of emotion differentiation and regulation: Experience tunes the appraisal thresholds of emotional development in infancy

In this review, we synthesize evidence to highlight cognitive appraisal as an important developmental antecedent of individual differences in emotion differentiation and adept emotion regulation. Emotion differentiation is the degree to which emotions are experienced in a nuanced or "granular" way-as specific and separable phenomena. More extensive differentiation is related to positive wellbeing and has emerged as a correlate of emotion regulation skill among adults. We argue that the cognitive appraisal processes that underlie these facets of emotional development are instantiated early in the first year of life and tuned by environmental input and experience. Powerful socializing input in the form of caregivers' contingent and selective responding to infants' emotional signals carves and calibrates the infant's appraisal thresholds for what in their world ought to be noticed, deemed as important or personally meaningful, and responded to (whether and how). These appraisal thresholds are thus unique to the individual child despite the ubiquity of the appraisal process in emotional responding. This appraisal infrastructure, while plastic and continually informed by experience across the lifespan, likely tunes subsequent emotion differentiation, with implications for children's emotion regulatory choices and skills. We end with recommendations for future research in this area, including the urgent need for developmental emotion science to investigate the diverse sociocultural contexts in which children's cognitive appraisals, differentiation of emotions, and regulatory responses are being built across childhood.

Dangerous Ground: One-Year-Old Infants are Sensitive to Peril in Other Agents' Action Plans

Do infants appreciate that other people's actions may fail, and that these failures endow risky actions with varying degrees of negative utility (i.e., danger)? Three experiments, including a pre-registered replication, addressed this question by presenting 12- to 15-month-old infants (N = 104, 52 female, majority White) with an animated agent who jumped over trenches of varying depth towards its goals. Infants expected the agent to minimize the danger of its actions, and they learned which goal the agent preferred by observing how much danger it risked to reach each goal, even though the agent's actions were physically identical and never failed. When we tested younger, 10-month-old infants (N = 102, 52 female, majority White) in a fourth experiment, they did not succeed consistently on the same tasks. These findings provide evidence that one-year-old infants use the height that other agents could fall from in order to explain and predict those agents' actions.

Adopted Utility Calculus: Origins of a Concept of Social Affiliation

To successfully navigate their social world, humans need to understand and map enduring relationships between people: Humans need a concept of social affiliation. Here I propose that the initial concept of social affiliation, available in infancy, is based on the extent to which one individual consistently takes on the goals and needs of another. This proposal grounds affiliation in intuitive psychology, as formalized in the naive-utility-calculus model. A concept of affiliation based on interpersonal utility adoption can account for findings from studies of infants' reasoning about imitation, similarity, helpful and fair individuals, "ritual" behaviors, and social groups without the need for additional innate mechanisms such as a coalitional psychology, moral sense, or general preference for similar others. I identify further tests of this proposal and also discuss how it is likely to be relevant to social reasoning and learning across the life span.

Emotion as Information in Early Social Learning

The majority of research on infants’ and children’s understanding of emotional expressions has focused on their abilities to use emotional expressions to infer how other people feel. However, an emerging body of work suggests that emotional expressions support rich, powerful inferences not just about emotional states but also about other unobserved states, such as hidden events in the physical world and mental states of other people (e.g., beliefs and desires). Here we argue that infants and children harness others’ emotional expressions as a source of information for learning about the physical and social world broadly. This “emotion as information” framework integrates affective, developmental, and computational cognitive sciences, extending the scope of signals that count as “information” in early learning.

Preferential responses to faces in superior temporal and medial prefrontal cortex in three-year-old children

Perceiving faces and understanding emotions are key components of human social cognition. Prior research with adults and infants suggests that these social cognitive functions are supported by superior temporal cortex (STC) and medial prefrontal cortex (MPFC). We used functional near-infrared spectroscopy (fNIRS) to characterize functional responses in these cortical regions to faces in early childhood. Three-year-old children (n = 88, M(SD) = 3.15(.16) years) passively viewed faces that varied in emotional content and valence (happy, angry, fearful, neutral) and, for fearful and angry faces, intensity (100%, 40%), while undergoing fNIRS. Bilateral STC and MPFC showed greater oxygenated hemoglobin concentration values to all faces relative to objects. MPFC additionally responded preferentially to happy faces relative to neutral faces. We did not detect preferential responses to angry or fearful faces, or overall differences in response magnitude by emotional valence (100% happy vs. fearful and angry) or intensity (100% vs. 40% fearful and angry). In exploratory analyses, preferential responses to faces in MPFC were not robustly correlated with performance on tasks of early social cognition. These results link and extend adult and infant research on functional responses to faces in STC and MPFC and contribute to the characterization of the neural correlates of early social cognition.

Let’s Talk About Emotions: the Development of Children’s Emotion Vocabulary from 4 to 11 Years of Age

Learning to use language in an adult-like way is a long-lasting process. This may particularly apply to complex conceptual domains such as emotions. The present study examined children’s and adults’ patterns of emotion word usage regarding their convergence and underlying semantic dimensions, and the factors influencing the ease of emotion word learning. We assessed the production of emotion words by 4- to 11-year-old children (N = 123) and 27 adults (M = 37 years) using a vignette test. We found that the older the children, the more emotion words they produced. Moreover, with increasing age, children’s pattern of emotion word usage converged with adult usage. The analysis for semantic dimensions revealed one clear criterion—the differentiation of positive versus negative emotions—for all children and adults. We further found that broad covering emotion words are produced earlier and in a more adult-like way.

Preschool-Aged Children Jointly Consider Others' Emotional Expressions and Prior Knowledge to Decide When to Explore

Emotional expressions are abundant in children's lives. What role do they play in children's causal inference and exploration? This study investigates whether preschool-aged children use others' emotional expressions to infer the presence of unknown causal functions and guide their exploration accordingly. Children (age: 3.0-4.9; N = 112, the United States) learned about one salient causal function of a novel toy and then saw an adult play with it. Children explored the toy more when the adult expressed surprise than when she expressed happiness (Experiment 1), but only when the adult already knew about the toy's salient function (Experiment 2). These results suggest that children consider others' knowledge and selectively interpret others' surprise as vicarious prediction error to guide their own exploration.

Applying Probabilistic Programming to Affective Computing

Affective Computing is a rapidly growing field spurred by advancements in artificial intelligence, but often, held back by the inability to translate psychological theories of emotion into tractable computational models. To address this, we propose a probabilistic programming approach to affective computing, which models psychological-grounded theories as generative models of emotion, and implements them as stochastic, executable computer programs. We first review probabilistic approaches that integrate reasoning about emotions with reasoning about other latent mental states (e.g., beliefs, desires) in context. Recently-developed probabilistic programming languages offer several key desidarata over previous approaches, such as: (i) flexibility in representing emotions and emotional processes; (ii) modularity and compositionality; (iii) integration with deep learning libraries that facilitate efficient inference and learning from large, naturalistic data; and (iv) ease of adoption. Furthermore, using a probabilistic programming framework allows a standardized platform for theory-building and experimentation: Competing theories (e.g., of appraisal or other emotional processes) can be easily compared via modular substitution of code followed by model comparison. To jumpstart adoption, we illustrate our points with executable code that researchers can easily modify for their own models. We end with a discussion of applications and future directions of the probabilistic programming approach.

Cultural Similarities and Differences in the Development of Sociomoral Judgments: An Eye-Tracking Study

People integrate the valence of behavior and that of outcome when making moral judgments. However, the role of culture in the development of this integration among young children remains unclear. We investigated cultural similarities and differences in moral judgments by measuring both visual attention and verbal evaluations. Three- and four-year-olds from Japan and the U.S. (N = 141) were shown sociomoral scenarios that varied in agents' behavior which reflected prosocial or antisocial intention and recipients' emotional outcome (happy, neutral, or sad); then, they were asked to evaluate agents' moral trait. Their eye fixations while observing moral scenarios were measured using an eye-tracker. We found culturally similar tendencies in the integration of behavior and outcome; however, a cultural difference was shown in their verbal evaluation. The link between implicit attention and explicit verbal evaluation was negligible. Both culturally shared and specific aspects of sociomoral development are discussed.

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.

Infants' Ability to Detect Emotional Incongruency: Deep or Shallow?

Infants can detect individuals who demonstrate emotions that are incongruent with an event and are less likely to trust them. However, the nature of the mechanisms underlying this selectivity is currently subject to controversy. The objective of this study was to examine whether infants' socio-cognitive and associative learning skills are linked to their selective trust. A total of 102 14-month-olds were exposed to a person who demonstrated congruent or incongruent emotional referencing (e.g., happy when looking inside an empty box), and were tested on their willingness to follow the emoter's gaze. Knowledge inference and associative learning tasks were also administered. It was hypothesized that infants would be less likely to trust the incongruent emoter and that this selectivity would be related to their associative learning skills, and not their socio-cognitive skills. The results revealed that infants were not only able to detect the incongruent emoter, but were subsequently less likely to follow her gaze toward an object invisible to them. More importantly, infants who demonstrated superior performance on the knowledge inference task, but not the associative learning task, were better able to detect the person's emotional incongruency. These findings provide additional support for the rich interpretation of infants' selective trust.

The Development of Negative Event-Emotion Matching in Infancy: Implications for Theories in Affective Science

Predicting another person's emotional response to a situation is an important component of emotion concept understanding. However, little is known about the developmental origins of this ability. The current studies examine whether 10-month-olds expect facial configurations/vocalizations associated with negative emotions (e.g., anger, disgust) to be displayed after specific eliciting events. In Experiment 1, 10-month-olds (N = 60) were familiarized to an Emoter interacting with objects in a positive event (Toy Given) and a negative event (Toy Taken). Infants expected the Emoter to display a facial configuration associated with anger after the negative event, but did not expect the Emoter to display a facial configuration associated with happiness after the positive event. In Experiment 2, 10- and 14-month-olds (N = 120) expected the Emoter to display a facial configuration associated with anger, rather than one associated with disgust, after an "anger-eliciting" event (Toy Taken). However, only the 14-month-olds provided some evidence of linking a facial configuration associated with disgust, rather than one associated with anger, to a "disgust-eliciting event" (New Food). Experiment 3 found that 10-month-olds (N = 60) did not expect an Emoter to display a facial configuration associated with anger after an "anger-eliciting" event involving an Unmet Goal. Together, these experiments suggest that infants start to refine broad concepts of affect into more precise emotion concepts over the first 2 years of life, before learning emotion language. These findings are a first step toward addressing a long-standing theoretical debate in affective science about the nature of early emotion concepts.

Understanding Social Display Rules: Using One Person's Emotional Expressions to Infer the Desires of Another

In social contexts, people’s emotional expressions may disguise their true feelings but still be revealing about the probable desires of their intended audience. This study investigates whether children can use emotional expressions in social contexts to recover the desires of the person observing, rather than displaying the emotion. Children (7.0–10.9 years, N = 211 across five experiments) saw a protagonist express one emotional expression in front of her social partner, and a different expression behind her partner’s back. Although the protagonist expressed contradictory emotions (and the partner expressed none), even 7‐year‐olds inferred both the protagonist’s and social partner’s desires. These results suggest that children can recover not only the desire of the person displaying emotion but also of the person observing it.

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.

Developmental progression of mental state understandings in infancy

This study establishes a sequence of developing mental state understandings in infants. We used three violation-of-expectation paradigms to assess fifty-seven 16-month-olds’ ability to (a) infer an actress’s intention from her prior repeated approaches to an object, (b) recognize her emotion by watching her facial-emotional display, and (c) deduce her false belief by noticing her lack of visual access to a change in the experimental setup. Contingencies between passing the three tasks were analyzed. Results showed that the infants made sense of intention first, followed by emotion, and then false belief. This progressive sequence parallels what has been found with preschoolers using verbal theory-of-mind tasks.

Computational Models of Emotion Inference in Theory of Mind: A Review and Roadmap

Research on social cognition has fruitfully applied computational modeling approaches to explain how observers understand and reason about others' mental states. By contrast, there has been less work on modeling observers' understanding of emotional states. We propose an intuitive theory framework to studying affective cognition-how humans reason about emotions-and derive a taxonomy of inferences within affective cognition. Using this taxonomy, we review formal computational modeling work on such inferences, including causal reasoning about how others react to events, reasoning about unseen causes of emotions, reasoning with multiple cues, as well as reasoning from emotions to other mental states. In addition, we provide a roadmap for future research by charting out inferences-such as hypothetical and counterfactual reasoning about emotions-that are ripe for future computational modeling work. This framework proposes unifying these various types of reasoning as Bayesian inference within a common "intuitive Theory of Emotion." Finally, we end with a discussion of important theoretical and methodological challenges that lie ahead in modeling affective cognition.

Children’s Judgments of Epistemic and Moral Agents: From Situations to Intentions

Children’s evaluations of moral and epistemic agents crucially depend on their discerning that an agent’s actions were performed intentionally. Here we argue that children’s epistemic and moral judgments reveal practices of forgiveness and blame, trust and mistrust, and objection or disapproval and that such practices are supported by children’s monitoring of the situational constraints on agents. Inherent in such practices is the understanding that agents are responsible for actions performed under certain conditions but not others. We discuss a range of situational constraints on children’s early epistemic and moral evaluations and clarify how these situational constraints serve to support children’s identification of intentional actions. By monitoring the situation, children distinguish intentional from less intentional action and selectively hold epistemic and moral agents accountable. We argue that these findings inform psychological and philosophical theorizing about attributions of moral and epistemic agency and responsibility.

Violations of Core Knowledge Shape Early Learning

Research on cognitive development has revealed that even the youngest minds detect and respond to events that adults find surprising. These surprise responses suggest that infants have a basic set of "core" expectations about the world that are shared with adults and other species. However, little work has asked what purpose these surprise responses serve. Here we discuss recent evidence that violations of core knowledge offer special opportunities for learning. Infants and young children make predictions about the world on the basis of their core knowledge of objects, quantities, and social entities. We argue that when these predictions fail to match the observed data, infants and children experience an enhanced drive to seek and retain new information. This impact of surprise on learning is not equipotent. Instead, it is directed to entities that are relevant to the surprise itself; this drive propels children-even infants-to form and test new hypotheses about surprising aspects of the world. We briefly consider similarities and differences between these recent findings with infants and children, on the one hand, and findings on prediction errors in humans and non-human animals, on the other. These comparisons raise open questions that require continued inquiry, but suggest that considering phenomena across species, ages, kinds of surprise, and types of learning will ultimately help to clarify how surprise shapes thought.

Fourteen-month-olds selectively search for and use information depending on the familiarity of the informant in both laboratory and home contexts

Infants are selective in their learning from others. However, there is only very limited research on the possible factors that shape this selectivity, especially when it comes to the impact of infants' familiarity with the informant and the context. The current study investigated whether 14-month-olds preferred to receive and use information provided by an unfamiliar informant (experimenter) compared with a familiar informant (parent) and whether this pattern depended on the context (home vs. laboratory). We tested infants either in the laboratory (n = 67) or in their home (n = 70). When both informants presented a novel object with positive or negative emotions, we measured infants' gaze behavior as an indicator for information search. When infants acted on the novel object themselves, we measured their exploratory behavior as an indicator of information use. Results revealed no effect of context on infants' information search and use. Rather, we found that the familiarity of informant had distinct effects on infant attention and object exploration. Namely, infants looked longer at the unfamiliar informant across contexts, but they explored more when the familiar informant presented the object compared with when the unfamiliar informant did so. Thus, during information search, 14-month-olds paid most attention to an unfamiliar source of information. However, participants explored the objects more when they came from a familiar source than when they came from an unfamiliar one. Possible explanations for these findings are discussed.

Rational Inference of Beliefs and Desires From Emotional Expressions

We investigated people's ability to infer others' mental states from their emotional reactions, manipulating whether agents wanted, expected, and caused an outcome. Participants recovered agents' desires throughout. When the agent observed, but did not cause the outcome, participants' ability to recover the agent's beliefs depended on the evidence they got (i.e., her reaction only to the actual outcome or to both the expected and actual outcomes; Experiments 1 and 2). When the agent caused the event, participants' judgments also depended on the probability of the action (Experiments 3 and 4); when actions were improbable given the mental states, people failed to recover the agent's beliefs even when they saw her react to both the anticipated and actual outcomes. A Bayesian model captured human performance throughout (rs ≥ .95), consistent with the proposal that people rationally integrate information about others' actions and emotional reactions to infer their unobservable mental states.

One- to four-year-olds connect diverse positive emotional vocalizations to their probable causes

We find that very young children make fine-grained distinctions among positive emotional expressions and connect diverse emotional vocalizations to their probable eliciting causes. Moreover, when infants see emotional reactions that are improbable, given observed causes, they actively search for hidden causes. The results suggest that early emotion understanding is not limited to discriminating a few basic emotions or contrasts across valence; rather, young children’s understanding of others’ emotional reactions is nuanced and causal. The findings have implications for research on the neural and cognitive bases of emotion reasoning, as well as investigations of early social relationships.

The ability to understand why others feel the way they do is critical to human relationships. Here, we show that emotion understanding in early childhood is more sophisticated than previously believed, extending well beyond the ability to distinguish basic emotions or draw different inferences from positively and negatively valenced emotions. In a forced-choice task, 2- to 4-year-olds successfully identified probable causes of five distinct positive emotional vocalizations elicited by what adults would consider funny, delicious, exciting, sympathetic, and adorable stimuli (Experiment 1). Similar results were obtained in a preferential looking paradigm with 12- to 23-month-olds, a direct replication with 18- to 23-month-olds (Experiment 2), and a simplified design with 12- to 17-month-olds (Experiment 3; preregistered). Moreover, 12- to 17-month-olds selectively explored, given improbable causes of different positive emotional reactions (Experiments 4 and 5; preregistered). The results suggest that by the second year of life, children make sophisticated and subtle distinctions among a wide range of positive emotions and reason about the probable causes of others’ emotional reactions. These abilities may play a critical role in developing theory of mind, social cognition, and early relationships.

Revisiting Young Children's Understanding of the Psychological Causes of Behavior

In 1989, Miller and Aloise challenged the prevailing belief that preschoolers tend to explain others' behavior in terms of external events or a person's physical attributes and have little understanding of psychological causes. That review documented preschoolers' understanding of, and even preference for, psychological causes as part of an emerging renaissance in developmental social-cognitive research. The present, updated review (97 articles, participant ages 3 months to 6 years) suggests the emergence of a transformative new perspective in which social-cognition is balanced between social and cognitive aspects rather than tilted toward cognition. Recent research on infants' awareness of mental states, young children's understanding of social categories and their judgments of the trustworthiness of informants, and cultural context reveals various ways in which preschoolers' social-causal reasoning is social.

Sample size, statistical power, and false conclusions in infant looking-time research

Infant research is hard. It is difficult, expensive, and time consuming to identify, recruit and test infants. As a result, ours is a field of small sample sizes. Many studies using infant looking time as a measure have samples of 8 to 12 infants per cell, and studies with more than 24 infants per cell are uncommon. This paper examines the effect of such sample sizes on statistical power and the conclusions drawn from infant looking time research. An examination of the state of the current literature suggests that most published looking time studies have low power, which leads in the long run to an increase in both false positive and false negative results. Three data sets with large samples (>30 infants) were used to simulate experiments with smaller sample sizes; 1000 random subsamples of 8, 12, 16, 20, and 24 infants from the overall samples were selected, making it possible to examine the systematic effect of sample size on the results. This approach revealed that despite clear results with the original large samples, the results with smaller subsamples were highly variable, yielding both false positive and false negative outcomes. Finally, a number of emerging possible solutions are discussed.

Formalizing emotion concepts within a Bayesian model of theory of mind

Sensitivity to others' emotions is foundational for many aspects of human life, yet computational models do not currently approach the sensitivity and specificity of human emotion knowledge. Perception of isolated physical expressions largely supplies ambiguous, low-dimensional, and noisy information about others' emotional states. By contrast, observers attribute specific granular emotions to another person based on inferences of how she interprets (or 'appraises') external events in relation to her other mental states (goals, beliefs, moral values, costs). These attributions share neural mechanisms with other reasoning about minds. Situating emotion concepts in a formal model of people's intuitive theories about other minds is necessary to effectively capture humans' fine-grained emotion understanding.

Inferring Beliefs and Desires From Emotional Reactions to Anticipated and Observed Events

Researchers have long been interested in the relation between emotion understanding and theory of mind. This study investigates a cue to mental states that has rarely been investigated: the dynamics of valenced emotional expressions. When the valence of a character's facial expression was stable between an expected and observed outcome, children (N = 122; M = 5.0 years) recovered the character's desires but did not consistently recover her beliefs. When the valence changed, older but not younger children recovered both the characters’ beliefs and desires. In contrast, adults jointly recovered agents’ beliefs and desires in all conditions. These results suggest that the ability to infer mental states from the dynamics of emotional expressions develops gradually through early and middle childhood.

Surprise! 20-month-old infants understand the emotional consequences of false beliefs

Recent studies suggest that by the second year of life, infants can attribute false beliefs to agents. However, prior studies have largely focused on infants' ability to predict a mistaken agent's physical actions on objects. The present research investigated whether 20-month-old infants could also reason about belief-based emotional displays. In Experiments 1 and 2, infants viewed an agent who shook two objects: one rattled and the other was silent. Infants expected the agent to express surprise at the silent object if she had a false belief that both objects rattled, but not if she was merely ignorant about the objects' properties. Experiment 3 replicated and extended these findings: if an agent falsely believed that two containers held toy bears (when only one did so), infants expected the agent to express surprise at the empty, but not the full, container. Together, these results provide the first evidence that infants in the second year of life understand the causal relationship between beliefs and emotional displays. These findings thus provide new evidence for false-belief understanding in infancy and suggest that infants, like older children, possess a robust understanding of belief that applies to a broad range of belief-based responses.

Toward an Integration of Deep Learning and Neuroscience

Neuroscience has focused on the detailed implementation of computation, studying neural codes, dynamics and circuits. In machine learning, however, artificial neural networks tend to eschew precisely designed codes, dynamics or circuits in favor of brute force optimization of a cost function, often using simple and relatively uniform initial architectures. Two recent developments have emerged within machine learning that create an opportunity to connect these seemingly divergent perspectives. First, structured architectures are used, including dedicated systems for attention, recursion and various forms of short- and long-term memory storage. Second, cost functions and training procedures have become more complex and are varied across layers and over time. Here we think about the brain in terms of these ideas. We hypothesize that (1) the brain optimizes cost functions, (2) the cost functions are diverse and differ across brain locations and over development, and (3) optimization operates within a pre-structured architecture matched to the computational problems posed by behavior. In support of these hypotheses, we argue that a range of implementations of credit assignment through multiple layers of neurons are compatible with our current knowledge of neural circuitry, and that the brain's specialized systems can be interpreted as enabling efficient optimization for specific problem classes. Such a heterogeneously optimized system, enabled by a series of interacting cost functions, serves to make learning data-efficient and precisely targeted to the needs of the organism. We suggest directions by which neuroscience could seek to refine and test these hypotheses.

The Developmental Origins of Selective Social Learning

The study of children's social learning is a topic of central importance to our understanding of human development. Learning from others allows children to acquire information efficiently; however, not all information conveyed by others is accurate or worth learning. A large body of research conducted over the past decade has shown that preschoolers learn selectively from some individuals over others. In the present article we summarize our work and that of others on the developmental origins of selective social learning during infancy. The results of these studies indicate that infants are sensitive to a number of cues, including competence, age, and confidence, when deciding from whom to learn. We highlight the important implications of this research in improving our understanding of the cognitive and social skills necessary for selective learning, and point out promising avenues for future research.