Children develop a complex understanding of honesty, promise-keeping and secret-keeping during early school years. Yet, these concepts have largely been examined in isolation and little is known about how they develop together across relational contexts, particularly in relation to children's trust beliefs. We investigated how age-related changes in children's trust vary across these bases and relational contexts in Sweden and Turkey, two societies that differ markedly in trust beliefs. Children aged 7–10 years (N = 200) rated their trust towards familiar and unfamiliar targets across hypothetical scenarios tapping each trust base. In Sweden, developmental changes in trust depended on both the trust base and the familiarity of the target. In contrast, in Turkey, age-related changes were driven primarily by growing selectivity based on target familiarity rather than by the trust base. These findings suggest that how trust attitudes are developmentally organized across trust bases and relational contexts may be shaped by children's broader sociocultural environment.

Interpersonal trust in others varies across societies with important implications. We examined the developmental course of this variability in Sweden and Turkey, two countries with distinct interpersonal trust attitudes. Two hundred children aged 7–10 (101 females, 99 males) rated how much they would trust others in hypothetical scenarios. Across cultures, children exhibited higher interpersonal trust for familiar than unfamiliar individuals. Further, trust towards familiar individuals increased with age in both countries, while trust towards unfamiliar individuals increased only in Sweden. Thus, greater trust for familiar over unfamiliar individuals became more pronounced with age in Turkey, a country characterized by a narrow trust radius and low interpersonal trust rates towards strangers. These findings suggest that societal disparities in trust beliefs emerge in childhood and highlight the importance of examining the underlying socialization processes.

Background People with Williams syndrome (WS) face challenges in various areas of cognitive processing, including attention. Previous studies suggest that these challenges are particularly pronounced when disengagement of attention from a previously attended stimulus is required, as compared to shifting attention without the need to disengage. Difficulties with attention could in turn be implicated in several of the behavioral characteristics of WS. Here, disengagement and shifting of visual attention, together with pupil dilation, were independently assessed in one of the largest eye-tracking studies of WS to date.

Methods We investigated shifting, disengagement, and the effects of auditory alerting cues on pupil dilation in WS individuals (n = 45, age range = 9–58 years), non-WS individuals with intellectual disability (ID) (n = 36, age range = 6–59 years), and typically developed (TD) infants (n = 32, age range = 6–7 months), children and adults (n = 31, age range = 9–60 years), using a modified gap-overlap task. Data were analyzed using linear mixed-effect models (LMMs).

Results Individuals with WS were less likely to shift their attention to upcoming targets than TD individuals (all ages), but more likely than the ID group to do so. When they did shift attention, participants with WS and ID were slower to initiate a gaze shift than TD participants regardless of whether disengagement was needed. In the WS group, failure to shift attention was strongly predicted by higher arousal (pupil dilation), which was induced by auditory alerting cues.

Conclusions Contrasting with previous theories of attention in WS, we found no evidence for a specific challenge in disengaging attention. Instead, our results point to a more general challenge in shifting attention. Reduced attention shifting in WS may be partly explained by atypical arousal regulation. These results contribute to our understanding of the WS phenotype.

Prosocial behaviour develops early in life yet also shows increasing gender differences over development, pointing to a role for learning and socialization connected to gender. Here, we examine prosocial behaviour in 5-year-old children (N = 54) in Sweden and how it relates to their binary gender as well as their self-rated gender identity, using two continuous scales. Prosocial behaviour was assessed using tasks for empathy, comforting, and anonymous costly sharing. We find that children are capable of identifying their gender beyond binary categories using continuous scales for identification with girls and with boys. Further, this variation in gender identity relates to their prosocial behaviour such that costly sharing is related to less identification with boys, particularly for boys. These findings shed light on the origins and development of gender differences in prosocial behaviour as well as children’s gender identity.

Children begin to reason about gender and others' gender-typed preferences from early in life, yet not enough is known about whether their reasoning reflects only binary categorization or a more nuanced way understanding of variation in gender. Further, little is known about how children's conception of their own gender affects how they think about others. In the current study, 3–6-year-old preschool children (n = 56) were asked to predict preferred and nonpreferred toys that included feminine, neutral, and masculine options for other children who were described using their binary gender identity (i.e., a gender-typical hairstyle, name, pronouns) and their home environment (i.e., room decoration and toys which were provided by their parents and were either feminine, neutral, or masculine). Children also participated in tasks to assess their own gender-typed toy preferences and their own gender identity using two continuous scales for identification with girls and with boys and their gender-typed behavior was rated by their preschool teachers. Results indicated that children considered both binary gender and information about the home environment when predicting others' toy preferences. Further, children's greater reliance on an individual's binary gender identity when allocating toys was related to the rigidity of their own gender identity and their own gender-typed toy preferences. Together, these findings add nuance to our understanding of children's developing reasoning about gender identity and preferences and reinforce that children can conceptualize gender as more than a binary category.

Typically developing humans automatically synchronize their arousal levels, resulting in pupillary contagion, or spontaneous adaptation of pupil size to that of others. This phenomenon emerges in infancy and is believed to facilitate social interaction. Williams syndrome (WS) is a genetic condition characterized by a hyper-social personality and social interaction challenges. Pupillary contagion was examined in individuals with WS (n = 44), age-parallel-matched typically developing children and adults (n = 65), and infants (n = 79). Bayesian statistics were used. As a group, people with WS did not show pupillary contagion (Bayes factors supporting the null: 25–50) whereas control groups did. This suggests a very early emerging atypical developmental trajectory. In WS, higher pupillary contagion was associated with lower autistic symptoms of social communication. Diminished synchronization of arousal may explain why individuals with WS have social challenges, whereas synchronization of arousal is not a necessary correlate of high social motivation.

Moving in time to others, as is often observed in dance, music, sports and much of children’s play cross-culturally, is thought to make people feel and act more prosocially towards each other. In a recent paper, Atwood et al. (2022) argued that the inferential validity of this link found between synchronous behaviour and prosociality might be mainly due to “expectancy effects generated by a combination of (1) experimenter expectancy, leading to experimenter bias; and (2) participant expectancy (i.e., placebo effects)”. Here, we counter these arguments with (1) examples of studies devoid of experimenter expectancy effects that nevertheless demonstrate a positive link between synchrony and prosociality, and (2) insights from the developmental literature that address participant expectancy by showing how expectations formed through lived experiences of synchronous interactions do not necessarily threaten inferential validity. In conclusion, there is already sufficient good-quality evidence showing the positive effects of synchronous behaviours on prosociality beyond what can be explained by experimenter or participant expectation effects.

Sensitivity to others’ emotional signals is an important factor for social interaction. While many studies of emotional reactivity focus on facial emotional expressions, signals such as pupil dilation which can indicate arousal, may also affect observers. For example, observers’ pupils dilate when viewing someone with dilated pupils, so-called pupillary contagion. Yet it is unclear how pupil size and emotional expression interact as signals. Further, examining individual differences in emotional reactivity to others can shed light on its mechanisms and potential outcomes. In the current study, adults’ (N = 453) pupil size was assessed while they viewed images of the eye region of individuals varying in emotional expression (neutral, happy, sad, fearful, angry) and pupil size (large, medium, small). Participants showed pupillary contagion regardless of the emotional expression. Individual differences in demographics (gender, age, socioeconomic status) and psychosocial factors (anxiety, depression, sleep problems) were also examined, yet the only factor related to pupillary contagion was socioeconomic status, with higher socioeconomic status predicting less pupillary contagion for emotionally-neutral stimuli. The results suggest that while pupillary contagion is a robust phenomenon, it can vary meaningfully across individuals. 

One of the great tasks of child development is to make sense of other people’s behavior by appealing to their internal thoughts, beliefs, and desires [“intuitive psychology” (1)], as well as the groups and relationships that they are a part of [“intuitive sociology” (2)]. There has long been debate over the extent to which these intuitions can be learned from social experience or whether they require some evolved capacity to interpret and categorize behavior. On page 311 of this issue, Thomas et al. (3) examine children’s intuitions about so-called “thick” relationships—intimate bonds that people have with kin or romantic partners that are characterized by certain behaviors and obligations (4). The authors suggest that saliva sharing between individuals is a cue that young children use to infer thick relationships, and that these inferences are based on evolutionary processes that have shaped how young children interpret the social world.