The costs and benefits of kindness for kids

What do children think makes an act kind? Which kind acts are children likely to perform? Previous research with adults suggests that the kindness of acts depends largely on the benefit provided and to a lesser extent on the cost incurred, and that adults are more likely to perform low-cost, high-benefit kind acts. In the current study, children (9-12 years, n = 945) and teens (13-17 years, n = 939) rated the benefit, cost, kindness, and likelihood of performing 173 acts of kindness, and adults (18+ years, n = 891) rated how beneficial, costly, kind, and likely the acts would be for young people to perform. Among children and teens, benefit but not cost predicted the kindness of acts, and benefit positively predicted, but cost negatively predicted, performance (for "kindness quotients" of 61% and 65%, respectively). Among adults, benefit and cost predicted the kindness of acts, and cost, but not benefit, negatively predicted performance (for a kindness quotient of 59%). The results for children and teens are similar to those from previous research with adults; however, adults are more sensitive to cost when rating kindness, are less sensitive to benefit when rating performance by young people, and are less likely to think young people will perform acts of kindness overall. In practical terms, the results suggest that recommending cost-effective acts may be the best way to encourage children to be kinder.

The effects of family, culture and sex on linguistic development across 20 languages

Languages vary in their complexity; caregivers vary in the way they structure their communicative interactions with children; and boys and girls can differ in their language skills. Using a multilevel modelling approach, we explored how these factors influence the path of language acquisition for young children growing up around the world (mean age 2-years 9-months; 56 girls). Across 43 different sites, we analysed 103 mother-child pairs who spoke 3,170,633 utterances, 16,209,659 morphemes, divided across 20 different languages: Afrikaans, Catalan, Cantonese, Danish, Dutch, English, Farsi, French, German, Hebrew, Icelandic, Irish, Italian, Japanese, Mandarin, Norwegian, Portuguese, Spanish, Swedish and Turkish. Using mean length of utterance (MLU) as a measure of language complexity and developmental skill, we found that variation in children's MLU was significantly explained by (a) between-language differences; namely the rate of child MLU growth was attuned to the complexity of their mother tongue, and (b) between-mother differences; namely mothers who used higher MLUs tended to have children with higher MLUs, regardless of which language they were learning and especially in the very young (<2.5 years-old). Controlling for family and language environment, we found no evidence of MLU sex differences in child speech nor in the speech addressed to boys and girls. By modelling language as a multilevel structure with cross-cultural variation, we were able to disentangle those factors that make children's pathway to language different and those that make it alike. RESEARCH HIGHLIGHTS: The speech of 103 mother-child pairs from 20 different languages showed large variation in the path of early language development. Language, family, but not the sex of the child, accounted for a significant proportion of individual differences in child speech, especially in the very young. The rate at which children learned language was attuned to the complexity of their mother tongue, with steeper trajectories for more complex language. Results demonstrate the relative influence of culture, family, and sex in shaping the path of language acquisition for different children.

Recalling experiences of scarcity reduces children's generosity relative to recalling abundance

Does a sense of having less or more than what one needs affect one's generosity? The question of how resource access influences prosocial behavior has received much attention in studies with adults but has produced conflicting findings. To better understand this relationship, we tested whether resource access affects generosity in the developing mind. In our preregistered investigation, we used a narrative recall method to explore how temporary, experimentally evoked states of resource abundance or scarcity affect children's sharing. In this study, 6- to 8-year-old American children (N = 148) recalled an experience of scarcity or abundance and then chose how many prizes to share with another child. We found that children in the scarce condition rated themselves as sadder, viewed their resource access as more limited, and shared fewer tokens than children in the abundant condition. Our results indicate that recalling past experiences of resource access creates distinct behavioral consequences for children and suggest that a sense of "having less" may encourage a strategy of resource conservation relative to a sense of "having more," even at a young age.

Approach-avoidance orientations can predict young children's decision-making

When facing situations that involve risk and reward, some may focus on the opportunity for reward, whereas others may focus on potential risks. Here, we used an original set of pictorial scenarios to try and predict 3- to 8-year-olds' reward-seeking and risk-avoiding behavior in three decision-making scenarios (N = 99; Mage = 5.6; 47% girls). We found that children's reward-risk tendencies did not predict sharing behavior in a dictator-game 'sharing' task. However, they predicted children's monopolizing behavior in a dictator-game 'taking' task and their preferences between taking home a 'risky' or a 'safe' reward in a novel prize-preference task. Overall, using a set of original pictorial scenarios to assess individual differences early on in development now provides initial evidence that bridges individual differences and decision-making domains and exposes behavioral patterns that were thus far hidden.

Children's consideration of collaboration and merit when making sharing decisions in private

Young children share equally when they acquire resources through collaboration with a partner, yet it is unclear whether they do so because in such contexts resources are encountered as common and distributed in front of the recipient or because collaboration promotes a sense of work-based fairness. In the current studies, 5- and 8-year-old children from Germany (N = 193) acquired resources either by working individually alongside or by collaborating with a peer. After finding out that the partner's container was empty, they decided in private whether they wanted to donate some resources to the peer. When both partners had worked with equal efforts (Study 1), children shared more after collaboration than after individual work. When one partner had worked with much more effort than the other (Study 2), children shared more with a harder-working partner than with a less-working partner independently of whether they had collaborated or worked individually. Younger children were more generous than older children, in particular after collaboration. These findings support the view that collaboration promotes a genuine sense of fairness in young children, but they also indicate that merit-based notions of fairness in the context of work may develop independently of collaboration, at least by the beginning of middle childhood and in Western societies.

Developing a sentence level fairness metric using word embeddings

Fairness is a principal social value that is observable in civilisations around the world. Yet, a fairness metric for digital texts that describe even a simple social interaction, e.g., 'The boy hurt the girl' has not been developed. We address this by employing word embeddings that use factors found in a new social psychology literature review on the topic. We use these factors to build fairness vectors. These vectors are used as sentence level measures, whereby each dimension reflects a fairness component. The approach is employed to approximate human perceptions of fairness. The method leverages a pro-social bias within word embeddings, for which we obtain an F1 = 79.8 on a list of sentences using the Universal Sentence Encoder (USE). A second approach, using principal component analysis (PCA) and machine learning (ML), produces an F1 = 86.2. Repeating these tests using Sentence Bidirectional Encoder Representations from Transformers (SBERT) produces an F1 = 96.9 and F1 = 100 respectively. Improvements using subspace representations are further suggested. By proposing a first-principles approach, the paper contributes to the analysis of digital texts along an ethical dimension.

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.

Priming Behavioral Control Enhances Sharing in Preschoolers

Although young children demonstrate knowledge of fairness norms, their actual sharing is often inconsistent with their understanding. A possible explanation for this discrepancy is the failure of behavioral control in young children. Thus, the present research manipulated behavioral control experimentally and examined its effect on the sharing behavior in 3- to 4-year-olds (N = 64). Children were randomly assigned to either the behavioral control or the neutral prime conditions. In the behavioral control prime condition, the children listened to a story in which a protagonist exerted behavioral control actively, refraining from eating candies. In the neutral prime condition, the children listened to a story in which a protagonist did not explicitly engage in behavioral control. The children then participated in the dictator game. The experimenter asked the children to share as many stickers as they wanted or should with an anonymous child. Children in the behavioral control prime condition shared more stickers than those in the neutral prime condition. However, the two groups did not differ in their judgments of fairness and emotional experiences. The current research provides evidence that preschoolers’ sharing behaviors can be facilitated by behavioral control.

Fairness takes time: Development of cooperative decision making in fairness context

The current study examined the development of fairness behavior and tested whether children's fair choices are fast and intuitive or slow and deliberate. Reaction times were measured while 4- to 9-year-olds (N = 94, 49 girls, 84.6% White) completed a novel social decision-making task contrasting fair choices with selfish choices. Fairness behavior increased during childhood, shifting from predominantly selfish choices among young children to fair choices by 7 years of age. Moreover, young children's fair choices were slow and deliberate, whereas reaction times did not predict older children's choices. These findings contrast with adults' intuitive cooperation and point to protracted development and learning of cooperative decision making in fairness contexts.

Economic trust in young children

Mutually beneficial interactions often require trust that others will reciprocate. Such interpersonal trust is foundational to evolutionarily unique aspects of human social behaviour, such as economic exchange. In adults, interpersonal trust is often assessed using the 'trust game', in which a lender invests resources in a trustee who may or may not repay the loan. This game captures two crucial elements of economic exchange: the potential for greater mutual benefits by trusting in others, and the moral hazard that others may betray that trust. While adults across cultures can trust others, little is known about the developmental origins of this crucial cooperative ability. We developed the first version of the trust game for use with young children that addresses these two components of trust. Across three experiments, we demonstrate that 4- and 6-year-olds recognize opportunities to invest in others, sharing more when reciprocation is possible than in a context measuring pure generosity. Yet, children become better with age at investing in trustworthy over untrustworthy partners, indicating that this cooperative skill emerges later in ontogeny. Together, our results indicate that young children can engage in complex economic exchanges involving judgements about interpersonal trust and show increasing sensitivity to appropriate partners over development.

Children, but not great apes, respect ownership

Access to and control of resources is a major source of costly conflicts. Animals, under some conditions, respect what others control and use (i.e. possession). Humans not only respect possession of resources, they also respect ownership. Ownership can be viewed as a cooperative arrangement, where individuals inhibit their tendency to take others' property on the condition that those others will do the same. We investigated to what degree great apes follow this principle, as compared to human children. We conducted two experiments, in which dyads of individuals could access the same food resources. The main test of respect for ownership was whether individuals would refrain from taking their partner's resources even when the partner could not immediately access and control them. Captive apes (N = 14 dyads) failed to respect their partner's claim on food resources and frequently monopolized the resources when given the opportunity. Human children (N = 14 dyads), tested with a similar apparatus and procedure, respected their partner's claim and made spontaneous verbal references to ownership. Such respect for the property of others highlights the uniquely cooperative nature of human ownership arrangements.

Giving Is Nicer than Taking: Preschoolers Reciprocate Based on the Social Intentions of the Distributor

Recent research has found that even preschoolers give more resources to others who have previously given resources to them, but the psychological bases of this reciprocity are unknown. In our study, a puppet distributed resources between herself and a child by taking some from a pile in front of the child or else by giving some from a pile in front of herself. Although the resulting distributions were identical, three- and five-year-olds reciprocated less generously when the puppet had taken rather than given resources. This suggests that children’s judgments about resource distribution are more about the social intentions of the distributor and the social framing of the distributional act than about the amount of resources obtained. In order to rule out that the differences in the children’s reciprocal behavior were merely due to experiencing gains and losses, we conducted a follow-up study. Here, three- and-five year olds won or lost resources in a lottery draw and could then freely give or take resources to/from a puppet, respectively. In this study, they did not respond differently after winning vs. losing resources.