Novel paradigms to measure variability of behavior in early childhood: posture, gaze, and pupil dilation

From pre-processing to advanced dynamic modeling of pupil data

The pupil of the eye provides a rich source of information for cognitive scientists, as it can index a variety of bodily states (e.g., arousal, fatigue) and cognitive processes (e.g., attention, decision-making). As pupillometry becomes a more accessible and popular methodology, researchers have proposed a variety of techniques for analyzing pupil data. Here, we focus on time series-based, signal-to-signal approaches that enable one to relate dynamic changes in pupil size over time with dynamic changes in a stimulus time series, continuous behavioral outcome measures, or other participants' pupil traces. We first introduce pupillometry, its neural underpinnings, and the relation between pupil measurements and other oculomotor behaviors (e.g., blinks, saccades), to stress the importance of understanding what is being measured and what can be inferred from changes in pupillary activity. Next, we discuss possible pre-processing steps, and the contexts in which they may be necessary. Finally, we turn to signal-to-signal analytic techniques, including regression-based approaches, dynamic time-warping, phase clustering, detrended fluctuation analysis, and recurrence quantification analysis. Assumptions of these techniques, and examples of the scientific questions each can address, are outlined, with references to key papers and software packages. Additionally, we provide a detailed code tutorial that steps through the key examples and figures in this paper. Ultimately, we contend that the insights gained from pupillometry are constrained by the analysis techniques used, and that signal-to-signal approaches offer a means to generate novel scientific insights by taking into account understudied spectro-temporal relationships between the pupil signal and other signals of interest.

Seeing awe: How children perceive awe-inspiring visual experiences

Awe is a profound, self-transcendent emotion. To illuminate its origin, four preregistered studies examined how U.S. 4- to 9-year-old children perceive awe-inspiring stimuli (N = 444, 55% female, 58% White, tested in 2020-2023). Awe-inspiring expansive nature (Study 1) and natural disaster scenes (Study 2) evoked perceived vastness, motivation to explore, and awareness of the unknown more than everyday scenes did (d ranging 0.32-1.76). Compared to expansive social stimuli, expansive nature stimuli more positively affected children's sense of self (Study 3). Diverse awe-inspiring scenes (vast nature, natural disasters, and slow-motion objects) all elicited awe and higher learning motivation than everyday scenes did (Study 4). These findings suggest that children appreciate awe-inspiring visual experiences, illuminating the origins and nature of awe as a self-transcendent experience.

Children's affective involvement in early word learning

The current study set out to examine the underlying physiological mechanisms of and the emotional response associated with word learning success in young 3-year-old predominantly white children. In particular, we examined whether children's physiological arousal following a word learning task predicts their word learning success and whether successful learning in turn predicts children's subsequent positive emotions. We presented children (n = 50) with a cross-situational word learning task and measured their pupillary arousal following completion of the task, as well as changes to their upper body posture following completion of the task, as indices of children's emotions following task completion. Children who showed greater physiological arousal following the novel word recognition task (n = 40) showed improved subsequent word recognition performance. We found that children showed more elevated posture after completing a familiar word learning task compared to completing a novel word learning task (n = 33) but results on children's individual learning success and postural elevation were mixed. We discuss the findings with regards to children's affective involvement in word learning.

The pupillometry of the possible: an investigation of infants' representation of alternative possibilities

Contrasting possibilities has a fundamental adaptive value for prediction and learning. Developmental research, however, has yielded controversial findings. Some data suggest that preschoolers might have trouble in planning actions that take into account mutually exclusive possibilities, while other studies revealed an early understanding of alternative future outcomes based on infants' looking behaviour. To better understand the origin of such abilities, here we use pupil dilation as a potential indicator of infants' representation of possibilities. Ten- and 14-month-olds were engaged in an object-identification task by watching video animations where three different objects with identical top parts moved behind two screens. Importantly, a target object emerged from one of the screens but remained in partial occlusion, revealing only its top part, which was compatible with a varying number of possible identities. Just as adults' pupil diameter grows monotonically with the amount of information held in memory, we expected that infants' pupil size would increase with the number of alternatives sustained in memory as candidate identities for the partially occluded object. We found that pupil diameter increased with the object's potential identities in 14- but not in 10-month-olds. We discuss the implications of these results for the foundation of humans' capacities to represent alternatives. This article is part of the theme issue 'Thinking about possibilities: mechanisms, ontogeny, functions and phylogeny'.

The ontogeny of children's social emotions in response to (un)fairness

Humans have a deeply rooted sense of fairness, but its emotional foundation in early ontogeny remains poorly understood. Here, we asked if and when 4- to 10-year-old children show negative social emotions, such as shame or guilt, in response to advantageous unfairness expressed through a lowered body posture (measured using a Kinect depth sensor imaging camera). We found that older, but not younger children, showed more negative emotions, i.e. a reduced upper body posture, after unintentionally disadvantaging a peer on (4,1) trials than in response to fair (1,1) outcomes between themselves and others. Younger children, in contrast, expressed more negative emotions in response to the fair (1,1) split than in response to advantageous inequity. No systematic pattern of children's emotional responses was found in a non-social context, in which children divided resources between themselves and a non-social container. Supporting individual difference analyses showed that older children in the social context expressed negative emotions in response to advantageous inequity without directly acting on this negative emotional response by rejecting an advantageously unfair offer proposed by an experimenter at the end of the study. These findings shed new light on the emotional foundation of the human sense of fairness and suggest that children's negative emotional response to advantageous unfairness developmentally precedes their rejection of advantageously unfair resource distributions.

The ontogeny of children's social emotions in response to (un)fairness

Humans have a deeply rooted sense of fairness, but its emotional foundation in early ontogeny remains poorly understood. Here, we asked if and when 4- to 10-year-old children show negative social emotions, such as shame or guilt, in response to advantageous unfairness expressed through a lowered body posture (measured using a Kinect depth sensor imaging camera). We found that older, but not younger children, showed more negative emotions, i.e. a reduced upper body posture, after unintentionally disadvantaging a peer on (4,1) trials than in response to fair (1,1) outcomes between themselves and others. Younger children, in contrast, expressed more negative emotions in response to the fair (1,1) split than in response to advantageous inequity. No systematic pattern of children's emotional responses was found in a non-social context, in which children divided resources between themselves and a non-social container. Supporting individual difference analyses showed that older children in the social context expressed negative emotions in response to advantageous inequity without directly acting on this negative emotional response by rejecting an advantageously unfair offer proposed by an experimenter at the end of the study. These findings shed new light on the emotional foundation of the human sense of fairness and suggest that children's negative emotional response to advantageous unfairness developmentally precedes their rejection of advantageously unfair resource distributions.

Quality of Life Outcomes With Creative Arts Therapy in Children With Cancer

Introduction: Children with cancer experience distress and decreased quality of life (QOL). Creative arts therapy (CAT) is a therapeutic modality which may improve QOL. This study examined the relationship between CAT and QOL in children and adolescents with cancer. Secondary aims explored relationships between CAT and emotional reactions, resilience, and posture (to investigate future potential as an objective biomarker of QOL). Methods: Children aged 3-18 years undergoing cancer treatments and a parent proxy completed the PedsQL3.0 Cancer Module, Faces Scale for emotional reactions, Resilience Scale in adolescents (>12 years), and an inclinometer to measure thoracic kyphosis before and after CAT. CAT exposure (number of sessions) was recorded. Results: Ninety-eight children with cancer (mean age 7.8 years, range 3-17) and parent proxy were enrolled. Of the 83 participants included in the final analysis, 18 received no CAT, 32 received low dose, and 33 received high dose CAT. A significant improvement in QOL was seen with high dose CAT in (slope change, p  =  .015), but the overall time by group interaction was not significant. Slope change response patterns suggested that CAT led to improved posture as compared to no CAT (time by group interaction, p  =  .044). Discussion: CAT may be an effective intervention to improve QOL in this population. Because initial evidence suggests that posture also improves with CAT, further investigation of posture as a potential objective biomarker of QOL is supported. Further study with a randomized controlled trial is warranted.

Young children show negative emotions after failing to help others

Self-conscious emotions, such as guilt and shame, motivate the adherence to social norms, including to norms for prosociality. The relevance of an observing audience to the expression of negative self-conscious emotions remains poorly understood. Here, in two studies, we investigated the influence of being observed on 4- to 5-year-old children's (N = 161) emotional response after failing to help someone in need and after failing to complete their own goal. As an index of children's emotional response, we recorded the change in children's upper body posture using a motion depth sensor imaging camera. Failing to help others lowered children's upper body posture regardless of whether children were observed by an audience or not. Children's emotional response was similar when they failed to help and when they failed to complete their own goal. In Study 2, 5-year-olds showed a greater decrease in upper body posture than 4-year-olds. Our findings suggest that being observed is not a necessary condition for young children to express a negative self-conscious emotion after failing to help or after failing to complete their own goal. We conclude that 5-year-olds, more so that 4-year-olds, show negative emotions when they fail to adhere to social norms for prosociality.

Preschool children's evaluations of their own unjustified requests

To make a fair request, requesters should consider the perspective of the requestee and contrast his or her needs with their own needs. Making an unjustified request (e.g., requesting something we do not need but the requestee does need) can induce some negative feelings such as guilt. Here, we investigated whether making unjustified requests resulted in negative emotions in 3- and 5-year-old children. Participants (N = 83; 34 girls) requested resources that they did or did not need from an experimenter who either did or did not need them. Both age groups were slower and more hesitant to make an unjustified request (children did not need the sticker, but the experimenter did) and also showed lowered body posture when making an unjustified request compared with when making a justified request (children needed the sticker, but the experimenter did not). Three-year-olds showed more pronounced changes in their posture, whereas 5-year-olds' emotional expression was overall more blunted. Rather, older children relied more on verbal indirect utterances (e.g., "You've got lovely stickers"), as opposed to direct requests (e.g., "Can I have that sticker?"), when making unjustified requests. These results suggest that preschool children already apply impartial normative standards to their requests for help, account for the fairness of their requests, and consider the needs of others when requesting.

Associations between demographics and quality of life in children in the first year of cancer treatment

Symptom distress and decreased quality of life (QOL) among children with cancer are well documented. Research is emerging on the child's voice in QOL-symptom reports, but existing QOL questionnaires are burdensome and objective biologic markers are lacking. We examined children's symptoms and QOL from parent and child perspectives and compared the results to one biologic marker (body posture). A cross-sectional secondary analysis of prospective data from children receiving creative arts therapy explored potential associations among demographics with and between QOL measures (PedsQL, Faces Scale, posture). Children (n = 98) ranged in age from 3 to 17 years (M = 7.8) and were in the first year of cancer treatment. No significant associations were found among the child's sex, race/ethnicity, socioeconomic status (SES), or distance from hospital, and total PedsQL. Older age was associated with worse total PedsQL, pain, nausea, worry, and posture (all P < 0.05). Greater worry (β = 0.51) and worse posture (β = 0.41) were the QOL variables most strongly correlated with older age. Poorer posture was associated with worse child PedsQL (total score, nausea, treatment anxiety, cognitive) and parent PedsQL (pain, nausea). Worse scores on the Faces Scale, PedsQL, and posture were all correlated (r = 0.21-0.39, all P < 0.05). Interventions to improve QOL could target nausea, worry, and older patients. Accuracy and interpretation of symptom distress in children are problematic. The Faces Scale and posture may be suitable, readily obtained measures of QOL in pediatric oncology that hold promise.

Pupil responses to dynamic negative facial expressions of emotion in infants and parents

Observing others’ emotions triggers physiological arousal in infants as well as in adults, reflected in dilated pupil sizes. This study is the first to examine parents’ and infants’ pupil responses to dynamic negative emotional facial expressions. Moreover, the links between pupil responses and negative emotional dispositions were explored among infants and parents. Infants’ and one of their parent's pupil responses to negative versus neutral faces were measured via eye tracking in 222 infants (5‐ to 7‐month‐olds, n = 77, 11‐ to 13‐month‐olds, n = 78, and 17‐ to 19‐month‐olds, n = 67) and 229 parents. One parent contributed to the pupil data, whereas both parents were invited to fill in questionnaires on their own and their infant's negative emotional dispositions. Infants did not differentially respond to negative expressions, while parents showed stronger pupil responses to negative versus neutral expressions. There was a positive association between infants' and their parent's mean pupil responses and significant links between mothers’ and fathers’ stress levels and their infants’ pupil responses. We conclude that a direct association between pupil responses in parents and offspring is observable already in infancy in typical development. Stress in parents is related to their infants’ pupillary arousal to negative emotions.

Cultural values shape the expression of self-evaluative social emotions

Social emotions are key to everyday social life and therefore shaped by cultural values in their expression. Prior research has focused on facial expressions of emotions. What is less clear, however, is the extent to which cultural values shape other modalities of emotional expression. In the present study, we applied a novel paradigm using depth sensor imaging technology to capture changes in participants’ body posture in real time. We aimed to (1) identify the nuances in the postural expression that are thought to characterize social emotions and (2) assess how individual differences in cultural values impact the postural expression of emotions. Participants in two separate studies were 132 undergraduate college students whose upper-body postural expansion was recorded after they recalled emotion episodes. Positive emotions elevated participants’ upper-body posture whereas negative emotions resulted in lowered upper-body posture. The effects on changes in upper-body posture were moderated by participants’ self-ratings of the vertical and horizontal dimensions of individualism and collectivism. The findings provide initial evidence of the nuances in the way cultural values influence the postural expression of emotions.

Visual preference for social vs. non-social images in young children with autism spectrum disorders. An eye tracking study

Autism Spectrum Disorders (ASD) are associated to social attention (SA) impairments. A gaze bias to non-social objects over faces has been proposed as an early marker of ASD. This bias may be related to the concomitant circumscribed interests (CI), which question the role of competing objects in this atypical visual behavior. The aim of this study was to compare visual attention patterns to social and non-social images in young children with ASD and matched typical controls (N = 36; age range 41-73 months) assessing the role of emotion in facial stimuli and the type of competing object. A paired preference task was designed pairing happy, angry, and neutral faces with two types of objects (related or not related to autism CI). Eye tracking data were collected, and three indexes were considered as dependent variables: prioritization (attentional orientation), preference, and duration (sustained attention). Results showed that both groups had similar visual pattern to faces (prioritization, more attention and longer visits to faces paired with objects non-related to their CI); however, the ASD group attended to faces significantly less than controls. Children with ASD showed an emotional bias (late orientation to angry faces and typical preference for happy faces). Finally, objects related to their CI captured attention in both groups, significantly reducing SA in children with ASD. Atypical SA is present in young children with ASD regardless the competing non-social object. Identifying strengths and difficulties in SA in this population may have substantial repercussion for early diagnosis, intervention, and ultimately prognosis.

Challenges in the comparative study of empathy and related phenomena in animals

The aim of this review is to discuss recent arguments and findings in the comparative study of empathy. Based on a multidisciplinary approach including psychology and ethology, we review the non-human animal literature concerning theoretical frameworks, methodology, and research outcomes. One specific objective is to highlight discrepancies between theory and empirical findings, and to discuss ambiguities present in current data and their interpretation. In particular, we focus on emotional contagion and its experimental investigation, and on consolation and targeted helping as measures for sympathy. Additionally, we address the feasibility of comparing across species with behavioural data alone. One main conclusion of our review is that animal research on empathy still faces the challenge of closing the gap between theoretical concepts and empirical evidence. To advance our knowledge, we propose to focus more on the emotional basis of empathy, rather than on possibly ambiguous behavioural indicators, and we provide suggestions to overcome the limitations of previous research .

Physiological regulation and social-emotional processing in female carriers of the FMR1 premutation

The FMR1 gene is associated with a wide range of clinical and cognitive phenotypes, ranging from intellectual disability and autism symptoms in fragile X syndrome (caused by the FMR1 full mutation), to a more varied, and still poorly understood range of clinical and cognitive phenotypes among carriers of the gene in its premutation state. Because the FMR1 premutation is relatively common among women (as high as 1 in 150), investigations of its phenotypic impact could have broad implications for understanding gene-behavior relationships underlying complex human traits, with potential clinical implications. This study investigated physiological regulation measured by pupillary responses, along with fixation patterns while viewing facial expressions among women who carry the FMR1 premutation (PM group; n = 47), to examine whether the FMR1 gene may relate to physiological regulation, social-emotional functioning, and social language skills (where subclinical differences have been previously reported among PM carriers that resemble those documented in autism-related conditions). Relative to controls (n = 25), the PM group demonstrated atypical pupillary responses and fixation patterns, controlling for IQ. In the PM group, pupillary response and fixation patterns were related to social cognition, social language abilities, and FMR1-related variation. Results indicate a pattern of atypical attention allocation among women who carry the FMR1 PM that could reflect different emotion-processing strategies mediated by autonomic dysregulation and the FMR1 gene. These findings lend insight into the FMR1 gene's potential contributions to complex human traits such as social emotional processing and social language.

Toddlers' intrinsic motivation to return help to their benefactor

A natural reaction to receiving help from someone is to help that person in return. In two studies, we investigated the developmental origins of children's motivation to return help. In Study 1, 18- and 24-month-old toddlers were either helped or not helped by an adult, and they could subsequently provide that adult with help or else observe another person providing help. We measured children's internal arousal, via changes in pupil dilation, both before and after help was provided. At both ages, children's internal arousal was higher when they could not help the adult who had previously helped them (and was lower when they could). On the other hand, if the adult needing help had not previously helped children, their internal arousal was equally low regardless of whether they or another person provided the help. Study 2 replicated this result and also found that if children had previously been helped but the person needing help was a different adult (not their benefactor), children's internal arousal was equally low regardless of whether they or another person provided the help. Together, these results suggest that young children are intrinsically motivated to return a received favor specifically to the previous benefactor, perhaps indicating a nascent sense of gratitude.

Increased sharing between collaborators extends beyond the spoils of collaboration

Research has shown that preschoolers increase equal sharing after collaborating to earn resources, suggesting that collaboration may be an important context for the development of fairness. The current study explored the influence of specific components of collaborative interactions to better understand the social cognitive foundations of this precocious increase in equal sharing. The effects of three forms of collaborative interaction on children's sharing were compared: collaborating toward a joint concrete goal of earning resources that could subsequently be shared, collaborating toward a joint concrete goal without earning resources, and playing a social game without earning resources. Replicating previous work, a significant increase in the proportion of equal sharing was observed when children shared collaboratively earned resources. Extending these findings, collaboration toward a concrete goal resulted in increased sharing regardless of whether resources were earned collaboratively or given outside of the collaborative context. Social play alone was not found to influence children's sharing, highlighting the importance of the context of collaboration toward a concrete goal to increase children's sharing. Overall, these findings suggest that collaborating toward a shared concrete goal fosters a general increase in prosociality that extends beyond the context of sharing collaboratively earned resources.

The Development of Prosocial Attention Across Two Cultures

Despite the significance of prosocial attention for understanding variability in children's prosociality little is known about its expression beyond infancy and outside the Western cultural context. In the current study we asked whether children's sensitivity to others' needs varies across ages and between a Western and Non-Western cultural group. We carried out a cross-cultural and cross-sectional eye tracking study in Kenya (n = 128) and Germany (n = 83) with children between the ages of 3 to 9 years old. Half the children were presented with videos depicting an instrumental helping situation in which one adult reached for an object while a second adult resolved or did not resolve the need. The second half of children watched perceptually controlled non-social control videos in which objects moved without any adults present. German children looked longer at the videos than Kenyan children who in turn looked longer at the non-social compared to the social videos. At the same time, children in both cultures and across all age groups anticipated the relevant solution to the instrumental problem in the social but not in the non-social control condition. We did not find systematic changes in children's pupil dilation in response to seeing the problem occur or in response to the resolution of the situation. These findings suggest that children's anticipation of how others' needs are best resolved is a cross-cultural phenomenon that persists throughout childhood.

Can Tai Chi and Qigong Postures Shape Our Mood? Toward an Embodied Cognition Framework for Mind-Body Research

Dynamic and static body postures are a defining characteristic of mind-body practices such as Tai Chi and Qigong (TCQ). A growing body of evidence supports the hypothesis that TCQ may be beneficial for psychological health, including management and prevention of depression and anxiety. Although a variety of causal factors have been identified as potential mediators of such health benefits, physical posture, despite its visible prominence, has been largely overlooked. We hypothesize that body posture while standing and/or moving may be a key therapeutic element mediating the influence of TCQ on psychological health. In the present paper, we summarize existing experimental and observational evidence that suggests a bi-directional relationship between body posture and mental states. Drawing from embodied cognitive science, we provide a theoretical framework for further investigation into this interrelationship. We discuss the challenges involved in such an investigation and propose suggestions for future studies. Despite theoretical and practical challenges, we propose that the role of posture in mind-body exercises such as TCQ should be considered in future research.

Zooming in on children's behavior during delay of gratification: Disentangling impulsigenic and volitional processes underlying self-regulation

When delaying gratification, both motivational and regulatory processes are likely to be at play; however, the relative contributions of motivational and regulatory influences on delay behavior are unclear. By examining behavioral responses during a delay task, this study sought to examine the motivational (anticipatory behavior) and regulatory mechanisms (executive function and self-control strategies) underlying children's self-regulation. The participants, 65 5- to 9-year-old children (M_age=7.19years, SD=0.89), were video-recorded during a delay procedure and later coded for anticipatory behaviors (e.g., gazing intensely at the tablet) and self-control strategies. Children also completed two executive function (EF) tasks. We found that anticipatory behavior was curvilinearly related to delay time. Children showing either very low or very high levels of anticipatory behavior were not able to wait the entire time. Furthermore, our results indicated that anticipatory behavior interacted with EF to predict delay time. Specifically, anticipatory behavior was negatively related to delay time only if EF abilities were low. Finally, self-control strategies also interacted with EF to predict children's ability to delay. Spontaneous engagement in self-control strategies such as fidgeting and engagement in alternative activities were beneficial for children with low EF but were unrelated to delay time for children with high EF. Results indicate the value of examining motivational and regulatory influences on delay behavior. Lapses in self-regulation may be due to the combination of powerful impulsigenic (i.e., anticipatory behavior) and weak volitional processes (i.e., EF, self-control strategies).