Children's moral reasoning about self- versus other-benefiting public health measures.

The COVID-19 pandemic has introduced novel public health measures such as masking and social distancing. In adults, framing these behaviors as benefiting others versus the self has been shown to affect people's perceptions of public health measures and willingness to comply. Here we asked whether self- versus other-oriented frames of novel public health measures influence children's endorsement and moral reasoning. Children aged 5 to 10 years viewed hypothetical dilemmas of aliens in which we manipulated the frame (other-oriented or self-oriented) of the prevention behavior and the severity (high or low) of the potential harm. Across two studies (Study 1: N = 48; Study 2: N = 61), results showed that across ages framing the behaviors as other-oriented, but not self-oriented, yielded more positive ratings of individuals who followed the public health measures and more negative ratings of those who did not. Across both frames, children generally endorsed these public health measures when the severity was high. Children used more moralizing concepts in other-oriented frames and were more critical of intentional transgressions over accidental transgressions, demonstrating further evidence that other-oriented frames induce moral reasoning. We discuss the theoretical and practical implications of these framing effects for sociomoral reasoning and action.

Children's judgments of interventions against norm violations: COVID-19 as a naturalistic case study.

The coronavirus pandemic has had a significant influence on social interactions, introducing novel social norms such as mask-wearing and social distancing to protect people's health. Because these norms and associated practices are completely novel, it is unknown how children assess what kinds of interventions are appropriate under what circumstances and what principles they draw on in their decisions. We investigated children's reasoning about interventions against individuals who failed to adhere to COVID-19 norms. In this pre-registered study (N = 128), 4- to 7-year-olds heard stories about a norm violator, that is, a person who refuses to wear a mask in class (COVID condition) or wear indoor shoes in class when his or her shoes are muddy (Muddy Shoes condition). Children evaluated four different interventions-giving a mask/indoor shoes (Giving), preventing the person from entering (Exclusion), throwing a paper ball at the person (Throwing), and not intervening (Doing Nothing)-in terms of their rightness, niceness, and effectiveness. We found that across measures children evaluated Giving most positively, whereas they viewed Throwing most negatively. Doing Nothing and Exclusion received mixed evaluations across measures, revealing nuanced judgments of these interventions in children. In most measures, there was no difference between the COVID and Muddy Shoes conditions, suggesting that children's evaluations are not specific to the novel COVID-19 context. Together, our results show that children dynamically evaluate each intervention, taking multiple factors into account. The current study has implications for the development of interventions against norm violations.

Why do children punish? Fair outcomes matter more than intent in children's second- and third-party punishment.

Humans punish fairness violations both as victims and as impartial third parties, which can maintain cooperative behavior. However, it is unknown whether similar motivations underlie punishment of unfairness in these two contexts. Here we approached this question by focusing on how both types of punishment develop in children, asking the question: What motivates young children to punish in response to fairness norm violations? We explored two potential factors: the direct experience of unfair outcomes and a partner's fair versus unfair intentions. The participants, 5- and 7-year-olds, were given the chance to engage in both second- and third-party punishment in response to either intended or unintended fairness norm violations in a single paradigm. In both age-groups, children were more likely to punish when they were directly affected by the allocation (second-party punishment) than when they were an uninvolved third party (third-party punishment). Reliable third-party punishment was shown only in the older age-group. Moreover, children's punishment was driven by outcome rather than intent, with equal rates of punishment when unequal outcomes were either the result of chance or the intentional act of another child. These findings suggest that younger children may be mainly motivated to create equal outcomes between themselves and others, whereas older children are motivated to enforce fairness norms as a general principle.

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.

Worth the wait: Children trade off delay and reward in self- and other-benefiting decisions.

Human prosocial behaviors are supported by early-emerging psychological processes that detect and fulfill the needs of others. However, little is known about the mechanisms that enable children to deliver benefits to others at costs to the self, which requires weighing other-regarding and self-serving preferences. We used an intertemporal choice paradigm to systematically study and compare these behaviors in 5-year-old children. Our results show that other-benefiting and self-benefiting behavior share a common decision-making process that integrates delay and reward. Specifically, we found that children sought to minimize delay and maximize reward, and traded off delays against rewards, regardless of whether these rewards were for the children themselves or another child. However, we found that children were more willing to invest their time to benefit themselves than someone else. Together, these findings show that from childhood, other- and self-serving decisions are supported by a general mechanism that flexibly integrates information about the magnitude of rewards, and the opportunity costs of pursuing them. A video abstract of this article can be viewed at: https://youtu.be/r8S0DGe7f8Q.

How Children Solve the Two Challenges of Cooperation.

In this review, I propose a new framework for the psychological origins of human cooperation that harnesses evolutionary theories about the two major problems posed by cooperation: generating and distributing benefits. Children develop skills foundational for identifying and creating opportunities for cooperation with others early: Infants and toddlers already possess basic skills to help others and share resources. Yet mechanisms that solve the free-rider problem-critical for sustaining cooperation as a viable strategy-emerge later in development and are more sensitive to the influence of social norms. I review empirical studies with children showing a dissociation in the origins of and developmental change seen in these two sets of processes. In addition, comparative studies of nonhuman apes also highlight important differences between these skills: The ability to generate benefits has evolutionary roots that are shared between humans and nonhuman apes, whereas there is little evidence that other apes exhibit comparable capacities for distributing benefits. I conclude by proposing ways in which this framework can motivate new developmental, comparative, and cross-cultural research about human cooperation.

Pay to play: Children's emerging ability to use acts of generosity for selfish ends.

Adults will offer favors to advance their standing and solicit a favor in return, using ostensibly prosocial acts strategically for selfish ends. Here we assessed the developmental emergence of such strategic behaviors in which individuals are generous to elicit future reciprocation from others. In a novel experimental paradigm with children aged 3 to 7 years, we tested whether children are willing to share more valuable resources when this act could prompt subsequent reciprocation. In an Experimental condition, children could share a more attractive or less attractive resource with a person who they knew would subsequently choose to play a game with either the children or another individual. In the Control condition, children knew the person would play alone. Across two studies, we found that over repeated trials, 5- and 7-year-olds, but not 3-year-olds, learned to share more valuable resources in the Experimental condition than in the Control condition. This shows that older age groups were able to quickly learn how to influence the subsequent partner choice in a novel situation. We address theoretical questions about the various types of reciprocity as being supported by different psychological mechanisms and discuss whether the current results could be explained by children's emerging ability for future-directed thinking.

Children's fairness in two Chinese schools: A combined ethnographic and experimental study.

Recent research has shown that children's sense of fairness is shaped in part by cultural practices, values, and norms. However, the specific social factors that motivate children's fairness decisions remain poorly understood. The current study combined an ethnographic approach with experimental tests of fairness (the Inequity Game) in two Chinese schools with qualitatively different practices and norms. In the "University school," children received explicit moral instruction on fairness reinforced by adults when supervising children's activities. By contrast, in the "Community school," children received less formal moral education and little adult supervision during play time, but norms of cooperation and fairness emerged through informal interactions with peers and other members of the community. Contrary to our predictions, children in both schools (N = 66) rejected both disadvantageous and advantageous allocations of resources in the test trials. However, in the very first practice trials, children from the Community school tended to reject all inequalities, whereas children from the University school tended to accept inequalities. We draw on the ethnographies of the schools to interpret these results, concluding that, despite the similarities in the experimental results, different motivations and social factors likely underlie the rejection of inequality in the two schools.

Conversation about the future self improves preschoolers' prospection abilities.

Prospection, the ability to engage in future-oriented thinking and decision making, begins to develop during the preschool years yet remains far from adult-like. One specific challenge for children of this age is with regard to thinking and reasoning about their future selves. Drawing from work indicating the importance of adult-child conversation in language and cognitive development, the current study examined the extent to which conversations about the future and the self may facilitate preschool-aged children's prospective thinking. The participants, 4- and 5-year-old children (N = 68), were randomly assigned to read books surrounding one of four topics with an adult experimenter: their present self, their future self, another child's present self, or another child's future self. Children whose conversations were centered on their future selves outperformed other children in the sample on a battery of prospection assessments taken immediately after the manipulation. Of the three prospection assessments administered, the manipulation had the strongest effect on children's prospective memories. Results are discussed in terms of the role that everyday conversation can play in fostering children's cognitive development during the early childhood years.

Collaboration encourages equal sharing in children but not in chimpanzees.

Humans actively share resources with one another to a much greater degree than do other great apes, and much human sharing is governed by social norms of fairness and equity. When in receipt of a windfall of resources, human children begin showing tendencies towards equitable distribution with others at five to seven years of age. Arguably, however, the primordial situation for human sharing of resources is that which follows cooperative activities such as collaborative foraging, when several individuals must share the spoils of their joint efforts. Here we show that children of around three years of age share with others much more equitably in collaborative activities than they do in either windfall or parallel-work situations. By contrast, one of humans' two nearest primate relatives, chimpanzees (Pan troglodytes), 'share' (make food available to another individual) just as often whether they have collaborated with them or not. This species difference raises the possibility that humans' tendency to distribute resources equitably may have its evolutionary roots in the sharing of spoils after collaborative efforts.

Development of in-group favoritism in children's third-party punishment of selfishness.

When enforcing norms for cooperative behavior, human adults sometimes exhibit in-group bias. For example, third-party observers punish selfish behaviors committed by out-group members more harshly than similar behaviors committed by in-group members. Although evidence suggests that children begin to systematically punish selfish behavior around the age of 6 y, the development of in-group bias in their punishment remains unknown. Do children start off enforcing fairness norms impartially, or is norm enforcement biased from its emergence? How does bias change over development? Here, we created novel social groups in the laboratory and gave 6- and 8-year-olds the opportunity to engage in costly third-party punishment of selfish sharing behavior. We found that by age 6, punishment was already biased: Selfish resource allocations received more punishment when they were proposed by out-group members and when they disadvantaged in-group members. We also found that although costly punishment increased between ages 6 and 8, bias in punishment partially decreased. Although 8-y-olds also punished selfish out-group members more harshly, they were equally likely to punish on behalf of disadvantaged in-group and out-group members, perhaps reflecting efforts to enforce norms impartially. Taken together, our results suggest that norm enforcement is biased from its emergence, but that this bias can be partially overcome through developmental change.

The psychology of cooperation: Insights from chimpanzees and children.

Across all cultures, humans engage in cooperative activities that can be as simple as preparing a meal or sharing food with others and as complex as playing in an orchestra or donating to charity. Although intraspecific cooperation exists among many other animal species, only humans engage in such a wide array of cooperative interaction and participate in large-scale cooperation that extends beyond kin and even includes strangers.

How comparative psychology can shed light on human evolution: Response to Beran et al.'s discussion of "Cognitive capacities for cooking in chimpanzees".

We recently reported a study (Warneken & Rosati Proceedings of the Royal Society B, 282, 20150229, 2015) examining whether chimpanzees possess several cognitive capacities that are critical to engage in cooking. In a subsequent commentary, Beran, Hopper, de Waal, Sayers, and Brosnan Learning & Behavior (2015) asserted that our paper has several flaws. Their commentary (1) critiques some aspects of our methodology and argues that our work does not constitute evidence that chimpanzees can actually cook; (2) claims that these results are old news, as previous work had already demonstrated that chimpanzees possess most or all of these capacities; and, finally, (3) argues that comparative psychological studies of chimpanzees cannot adequately address questions about human evolution, anyway. However, their critique of the premise of our study simply reiterates several points we made in the original paper. To quote ourselves: "As chimpanzees neither control fire nor cook food in their natural behavior, these experiments therefore focus not on whether chimpanzees can actually cook food, but rather whether they can apply their cognitive skills to novel problems that emulate cooking" (Warneken & Rosati Proceedings of the Royal Society B, 282, 20150229, 2015, p. 2). Furthermore, the methodological issues they raise are standard points about psychological research with animals-many of which were addressed synthetically across our 9 experiments, or else are orthogonal to our claims. Finally, we argue that comparative studies of extant apes (and other nonhuman species) are a powerful and indispensable method for understanding human cognitive evolution.

Give as I give: Adult influence on children's giving in two cultures.

Adult influence on children's altruistic behavior may differ between cultural communities. We used an experimental approach to assess the influence of adult models on children's altruistic giving in a city in the United States and rural villages in India. Children between 3 and 8 years of age were tested with their parents in the United States (n=163) and India (n=154). Parents modeled either a generous or stingy donation; children then performed a similar task in private. Children in both communities were influenced by the stingy model, but only children in India increased their giving after viewing a generous model. The model's influence also increased with age in India. Results of a questionnaire revealed that parents in both communities believed that children learned sharing behavior from them. We consider these results in light of differences between these societies, including different socialization goals, cultural values, and content biases that may affect altruistic giving.

Cognitive capacities for cooking in chimpanzees.

The transition to a cooked diet represents an important shift in human ecology and evolution. Cooking requires a set of sophisticated cognitive abilities, including causal reasoning, self-control and anticipatory planning. Do humans uniquely possess the cognitive capacities needed to cook food? We address whether one of humans' closest relatives, chimpanzees (Pan troglodytes), possess the domain-general cognitive skills needed to cook. Across nine studies, we show that chimpanzees: (i) prefer cooked foods; (ii) comprehend the transformation of raw food that occurs when cooking, and generalize this causal understanding to new contexts; (iii) will pay temporal costs to acquire cooked foods; (iv) are willing to actively give up possession of raw foods in order to transform them; and (v) can transport raw food as well as save their raw food in anticipation of future opportunities to cook. Together, our results indicate that several of the fundamental psychological abilities necessary to engage in cooking may have been shared with the last common ancestor of apes and humans, predating the control of fire.

The shadow of the future: 5-year-olds, but not 3-year-olds, adjust their sharing in anticipation of reciprocation.

Cooperation can be maintained if individuals reciprocate favors over repeated interactions. However, it is not known when during development the psychological capacities to engage in contingent reciprocation emerge. Therefore, we tested when children begin to differentiate between reciprocal and nonreciprocal interactions in their resource sharing. We compared the sharing behavior of 3- and 5-year-olds in two situations. In an experimental condition, the child and a puppet partner alternated the roles of donor and recipient. In a control condition, the puppet had no opportunity to reciprocate. Results showed that 5-year-olds, but not 3-year-olds, increased their sharing toward a potential reciprocator. In addition, we found that children's ability to delay gratification was positively related to their tendency to share in both conditions. These findings show that reciprocity in anticipation of repeated interactions emerges during middle childhood. Moreover, our results highlight the importance of the ability to delay gratification as a prerequisite for children's sharing. We discuss how children's emerging cognitive abilities enable reciprocal sharing in situations where a child must react to or anticipate a partner's behavior.

Children reject inequity out of spite.

When confronted with inequality, human children and adults sacrifice personal gain to reduce the pay-offs of other individuals, exhibiting apparently spiteful motivations. By contrast, sacrifice of personal gain by non-human animals is often interpreted as frustration. Spite may thus be a uniquely human motivator. However, to date, no empirical study has demonstrated that psychological spite actually drives human behaviour, leaving the motivation for inequity aversion unclear. Here, we ask whether 4- to 9-year-old children and adults reject disadvantageous inequity (less for self, more for peer) out of spite or frustration. We show that children, but not adults, are more likely to reject disadvantageous allocations when doing so deprives their peer of a better reward (spite) than when their peer has already received the better reward (frustration). Spiteful motivations are thus present early in childhood and may be a species-specific component of humans' developing cooperative and competitive behaviour.

Children's norm enforcement in their interactions with peers.

This study investigates how children negotiate social norms with peers. In Study 1, 48 pairs of 3- and 5-year-olds (N = 96) and in Study 2, 48 pairs of 5- and 7-year-olds (N = 96) were presented with sorting tasks with conflicting instructions (one child by color, the other by shape) or identical instructions. Three-year-olds differed from older children: They were less selective for the contexts in which they enforced norms, and they (as well as the older children to a lesser extent) used grammatical constructions objectifying the norms ("It works like this" rather than "You must do it like this"). These results suggested that children's understanding of social norms becomes more flexible during the preschool years.

Children's third-party punishment does not change depending on the prospect of future interaction.

Children pay a cost to punish third parties for unfairness. However, theoretical debates highlight that such behaviors could reflect a strategic attempt to manipulate others in future interactions. The personal deterrence hypothesis claims that punishment is motivated to deter future unfairness toward punishers. Here we tested this hypothesis with a total of n = 248 five- to 10-year-olds. In two experiments, participants witnessed that a divider shared resources either fairly or selfishly with a third party. Participants learned that the same divider (same divider condition) or a new divider (different divider condition) would subsequently decide how to share resources with the participant. If children's punishment is motivated by personal deterrence, they should punish unfairness more often in the same divider condition (vs. different divider). Conversely, if children fear retaliation from dividers, they should punish dividers less often in the same divider condition (vs. different divider). Children intervened by taking resources away from the divider (Experiment 1) or by sending a disapproving or an approving verbal message (Experiment 2). Children were more likely to punish unfair than fair allocations through material punishment and disapproving messages, while being more likely to reward fair than unfair allocations by sending approving messages. However, children did so at the same level regardless of their future divider's identity. We discuss how these results speak to a children's emerging concern with fairness and how it challenges the notion that children punish for self-oriented reasons as suggested by the personal deterrence hypothesis. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The emergence of contingent reciprocity in young children.

Contingent reciprocity is important in theories of the evolution of human cooperation, but it has been very little studied in ontogeny. We gave 2- and 3-year-old children the opportunity to either help or share with a partner after that partner either had or had not previously helped or shared with the children. Previous helping did not influence children's helping. In contrast, previous sharing by the partner led to greater sharing in 3-year-olds but not in 2-year-olds. These results do not support theories claiming either that reciprocity is fundamental to the origins of children's prosocial behavior or that it is irrelevant. Instead, they support an account in which children's prosocial behavior emerges spontaneously but is later mediated by reciprocity.