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

Mapping the mental space of emotional concepts through kinematic measures of decision uncertainty

Emotional concepts and their mental representations have been extensively studied. Yet, some ecologically relevant aspects, such as how they are processed in ambiguous contexts (e.g., in relation to other emotional stimuli that share similar characteristics), are incompletely known. We employed a similarity judgement of emotional concepts and manipulated the contextual congruency of the responses along the two main affective dimensions of hedonic valence and physiological activation, respectively. Behavioural and kinematics (mouse-tracking) measures were combined to gather a novel 'similarity index' between emotional concepts, to derive topographical maps of their mental representations. Self-report (interoceptive sensibility, positive-negative affectivity, depression) and physiological measures (heart rate variability, HRV) have been collected to explore their possible association with emotional conceptual representation. Results indicate that emotional concepts typically associated with low arousal profit by contextual congruency, with faster responses and reduced uncertainty when contextual ambiguity decreases. The emotional maps recreate two almost orthogonal axes of valence and arousal, and the similarity measure captures the smooth boundaries between emotions. The emotional map of a subgroup of individuals with low positive affectivity reveals a narrower conceptual distribution, with variations in positive emotions and in individuals with reduced arousal (such as those with reduced HRV). Our work introduces a novel methodology to study emotional conceptual representations, bringing the behavioural dynamics of decision-making processes and choice uncertainty into the affective domain. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

Sorting out emotions: How labels influence emotion categorization

The ability to categorize emotions has long-term implications for children's social and emotional development. Therefore, identifying factors that influence early emotion categorization is of great importance. Yet, whether and how language impacts emotion category development is still widely debated. The present study aimed to assess how labels influence young children's ability to group faces into emotion categories for both earliest-learned and later-learned emotion categories. Across two studies, 128 two- and 3-year-olds (77 female; Mean age = 3.04 years; 35.9% White, 12.5% Multiple ethnicities or races, 6.3% Asian, 3.1% Black, and 42.2% not reported) were presented with three emotion categories (Study 1 = happy, sad, angry; Study 2 = surprised, disgusted, afraid). Children sorted 30 images of adults posing stereotypical facial expressions into one of the three categories. Children were randomly assigned to either hear the emotion labels before sorting (e.g., "happy faces go here") or were not given labels (e.g., "faces like this go here"). Study 1 results indicated no significant effects of labels for earlier-learned emotion categories, F(1, 60) = .94, p = .337, ηp² = .013. However, the Study 2 results revealed that labels improved emotion categorization for later-learned categories, F(1, 60) = 8.15, p = .006, ηp² = .024. Taken together, these results suggest that labels are important for emotion categorization, but the impact of labels may depend on children's familiarity with the emotion category. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Acquiring Complex Communicative Systems: Statistical Learning of Language and Emotion

During the early postnatal years, most infants rapidly learn to understand two naturally evolved communication systems: language and emotion. While these two domains include different types of content knowledge, it is possible that similar learning processes subserve their acquisition. In this review, we compare the learnable statistical regularities in language and emotion input. We then consider how domain-general learning abilities may underly the acquisition of language and emotion, and how this process may be constrained in each domain. This comparative developmental approach can advance our understanding of how humans learn to communicate with others.

How Tone, Intonation and Emotion Shape the Development of Infants’ Fundamental Frequency Perception

Fundamental frequency (ƒ₀), perceived as pitch, is the first and arguably most salient auditory component humans are exposed to since the beginning of life. It carries multiple linguistic (e.g., word meaning) and paralinguistic (e.g., speakers’ emotion) functions in speech and communication. The mappings between these functions and ƒ₀ features vary within a language and differ cross-linguistically. For instance, a rising pitch can be perceived as a question in English but a lexical tone in Mandarin. Such variations mean that infants must learn the specific mappings based on their respective linguistic and social environments. To date, canonical theoretical frameworks and most empirical studies do not view or consider the multi-functionality of ƒ₀, but typically focus on individual functions. More importantly, despite the eventual mastery of ƒ₀ in communication, it is unclear how infants learn to decompose and recognize these overlapping functions carried by ƒ₀. In this paper, we review the symbioses and synergies of the lexical, intonational, and emotional functions that can be carried by ƒ₀ and are being acquired throughout infancy. On the basis of our review, we put forward the Learnability Hypothesis that infants decompose and acquire multiple ƒ₀ functions through native/environmental experiences. Under this hypothesis, we propose representative cases such as the synergy scenario, where infants use visual cues to disambiguate and decompose the different ƒ₀ functions. Further, viable ways to test the scenarios derived from this hypothesis are suggested across auditory and visual modalities. Discovering how infants learn to master the diverse functions carried by ƒ₀ can increase our understanding of linguistic systems, auditory processing and communication functions.

How the Emotional Environment Shapes the Emotional Life of the Child

Emotion understanding facilitates the development of healthy social interactions. To develop emotion knowledge, infants and young children must learn to make inferences about people's dynamically changing facial and vocal expressions in the context of their everyday lives. Given that emotional information varies so widely, the emotional input that children receive might particularly shape their emotion understanding over time. This review explores how variation in children's received emotional input shapes their emotion understanding and their emotional behavior over the course of development. Variation in emotional input from caregivers shapes individual differences in infants' emotion perception and understanding, as well as older children's emotional behavior. Finally, this work can inform policy and focus interventions designed to help infants and young children with social-emotional development.

Emotion words link faces to emotional scenarios in early childhood

Recent theories have suggested that emotion words may facilitate the development of emotion concepts. The present study investigates whether emotion words affect children's performance on an emotion category learning task. Across two experiments, 72 three-year-old children (49 female) were asked to identify which emotional face best matched particular emotional scenarios during nine pretest and nine posttest trials. The scenarios in the present studies aligned with emotions typically learned among older age groups (annoyed, disgusted, and nervous). Between pretest and posttest, children participated in training in which a facial configuration (annoyed, disgusted, or nervous) was paired with an associated scenario while they heard the emotion labeled explicitly or heard irrelevant information (Experiment 1) or heard a broad emotion label versus irrelevant information (Experiment 2). Aside from the labels presented, all other information was kept the same across conditions, including the specific faces and scenarios heard during learning trials. In Experiment 1, children's emotion understanding increased more from pretest to posttest in the explicit label versus irrelevant condition, t(34) = 2.26, p = .030, d = .75, but in Experiment 2 the broad emotion labels did not provide an advantage over irrelevant information, t(34) = .72, p = .474, d = .24. These results suggest that emotion labels may be particularly helpful for young children learning about unfamiliar emotions, because specific labels may help children to aggregate disparate emotional information into meaningful categories. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Assessing the Power of Words to Facilitate Emotion Category Learning

Previous research suggests that labels shape the categorization of emotional stimuli such as facial configurations, yet the strongest evidence of labels' influence on category learning comes from work on object categories. In particular, Lupyan et al. (Psychol Sci 18(12):1077-1083, 2007) found that novel categories of aliens were learned faster by participants provided with nonsense labels during feedback. We summarize a series of five studies in which we examined whether this word-enhancement effect on learning would extend to novel categories of emotion. These studies were conceptual replications of the paradigm used by Lupyan et al. (Psychol Sci 18(12):1077-1083, 2007) designed so that participants would associate novel expressive behaviors with situated experiences. We hypothesized that participants would learn to categorize exemplars of novel emotion categories over the duration of the task, and that categorization would be facilitated for participants who were presented with category labels during learning. We simultaneously analyzed data from all five studies in an integrative data analysis, allowing us to test the effects of learning over time and label condition with increased statistical power. Across all five studies, we found that, while participant performance did improve over time, in no case was it facilitated by including emotion labels at feedback. These results join others in suggesting that the effect of labels on emotion categorization may be more context-dependent than previously supposed-varying by the type of category learning task as well as the specific categories being learned and their relationship to previously acquired knowledge-such that there may be multiple pathways for emotion category learning.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42761-021-00084-4.

The representation of emotion knowledge across development

The present study examined how children spontaneously represent facial cues associated with emotion. 106 three‐ to six‐year‐old children (48 male, 58 female; 9.4% Asian, 84.0% White, 6.6% more than one race) and 40 adults (10 male, 30 female; 10% Hispanic, 30% Asian, 2.5% Black, 57.5% White) were recruited from a Midwestern city (2019–2020), and sorted emotion cues in a spatial arrangement method that assesses emotion knowledge without reliance on emotion vocabulary. Using supervised and unsupervised analyses, the study found evidence for continuities and gradual changes in children's emotion knowledge compared to adults. Emotion knowledge develops through an incremental learning process in which children change their representations using combinations of factors—particularly valence—that are weighted differently across development.

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.

Emotion Words in Early Childhood: A Language Transcript Analysis

Children learn the abstract, challenging categories of emotions from young ages, and it has recently been suggested that language (and more specifically emotion words) may aid this learning. To examine the language that young children hear and produce as they're learning emotion categories, the present study examined nearly 2,000 transcripts from 179 children ranging from 15- to 47-months from the Child Language Data Exchange System (CHILDES). Results provide key descriptive, developmental, and predictive information regarding child emotion language production, including the finding that child emotion word production was predicted by mothers' emotion word production (β=.21, p<.001), but not by child or mother language complexity (β=.01, p=.690; β=.00, p=.872). Frequency of specific emotion words are presented, as are developmental trends in early emotion language production and input. These results improve the understanding of children's daily emotional language environments and may inform theories of emotional development.

Adversity and Emotional Functioning

Exposure to early adversity has been linked to variations in emotional functioning. To date, however, the precise nature of these variations has been difficult to pinpoint given widespread differences in the ways in which aspects of emotional functioning are defined and measured. Here, more consistent with models of emotional functioning in typically developing populations (e.g., Halberstadt et al., 2001), we propose defining emotional functioning as consisting of distinct domains of emotion expression, perception, knowledge, reactivity, and regulation. We argue that this framework is useful for guiding hypothesis generation about the specific impact of early adversity on children's emotional functioning. We operationalize the construct of emotional functioning, highlight what is currently known about the association between adversity exposure and each domain of emotional functioning, propose potential mechanisms for these associations, and set the stage for future research examining the development of emotional functioning in the context of early adversity.

Examining Preverbal Infants' Ability to Map Labels to Facial Configurations

Language is important for emotion perception, but very little is known about how emotion labels are learned. The current studies examine how preverbal infants map novel labels onto facial configurations. Across studies, infants were tested with a modified habituation paradigm ("switch design"). Experiments 1 and 2 found that 18-month-olds, but not 14-month-olds, mapped novel labels ("blicket" and "toma") to human facial configurations associated with happiness and sadness. Subsequent analyses revealed that vocabulary size positively correlated with 14-month-olds' ability to form the mappings. Experiment 3 found that 14-month-olds were able to map novel labels to facial configurations when the visual complexity of the stimuli was reduced (i.e., by using cartoon facial configurations). This suggests that cognitive maturation and language development influence infants' associative word learning with facial configurations. The current studies are a critical first step in determining how infants navigate the complex process of learning emotion labels.

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.

Young Children Do Not Label Facial Expressions Spontaneously: A Brief Investigation of the Label Superiority Effect

A label superiority effect refers to the tendency of young children to categorize facial expressions based on emotion labels (e.g., "happy") more accurately than those based on photographs of facial expressions (e.g., "smile"). However, it is unclear whether this effect stems from inaccuracies in children's spontaneous labeling of facial expressions or their tendency not to label facial expressions spontaneously. To further explore the label superiority effect, Japanese children aged 3-5 years (N = 48) were assigned to one of three conditions: label cue, photo cue, and compelled to label, and asked to categorize facial expressions by emotion by placing cards in a box. The children correctly put more facial expressions in the box for label cues than photo cues, but the compelled to label group performed as well as the label cues group. These results suggest that the label superiority effect occurs because children do not label facial expressions spontaneously, and this tendency may explain their difficulty in understanding facial expressions.

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.