Theory of mind (TOM) is an important cognitive factor of children’s distributive justice and prosocial sharing. The multiple forces hypothesis indicates that TOM can help children balance their self-interest and the needs of others in distributive situations (Chen and Wu, 2017). Children who have passed the second-order false belief task allocated more resources to strangers than those who have not. Second-order false beliefs, likewise, did not affect children’s allocation to friends and relatives (Yu et al., 2016). These findings are consistent with the multiple forces hypothesis. However, the TOM predicted that children would distribute more stickers to their friends over time (Vonk et al., 2020). Priming children’s speculation on recipients’ goals in the competitive situation could significantly affect children’s allocation behavior and reduce children’s resources allocated to competitors (Nilsen and Valcke, 2018). Inducing children’s perspective taking significantly increases the rejection of unfair distribution (Tsoi and McAuliffe, 2019).

The multiple forces hypothesis indicates that the effect of the TOM is not obvious in relatively simple sharing situations. A meta-analysis found that children’s TOM was significantly associated with helping and cooperative among prosocial behaviors but not with sharing behaviors (Imuta et al., 2016). Nevertheless, in more complex sharing situations, TOM allows children to understand each other’s needs more accurately and quickly, thus promoting prosocial sharing behavior (Kogut et al., 2016). These results may indicate that when children have clear social norms to follow, the relationship between TOM and sharing behavior is no longer significant.

There are two main ways in which for children can obtain resources in an allocation situation: windfall gains and earned rewards. The former are directly provided by adults, making it a windfall for the distributor and recipient. The latter are obtained through effort (participation in collaborative or parallel work). In the case of windfall, infants in the first year of life already have the sensitivity to the fairness of third-party distribution (Buyukozer et al., 2019). The infants expect a reward to be distributed by a third party to the person who protects the victim from attack (Geraci, 2020; Geraci and Surian, 2021). Similarly, infants expect third parties to allocate comforter rewards, that go beyond the principle of equality (Geraci et al., 2021). Studies the use provided by adults have shown that disadvantageous inequity aversion appears around 4 years old, and advantageous inequity aversion appears at 8 years old (Blake and McAuliffe, 2011; McAuliffe et al., 2013). When the resources were obtained by the children’s own efforts, however, they can spontaneously distributed the rewards of cooperation equally among everyone as early as 3 years old. When they worked in parallel and received their rewards separately, they accepted the inequality of the results (Hamann et al., 2011). In short, children’s distributive equity is particularly sensitive to means of resource acquisition.

In a prosocial sharing study in children, researchers divided the resources into things occasionally gained and things one possesses according to the way in which they were acquired. The things occasionally gained were directly provided by the experimenter and thus were windfalls for the sharer; things one possess marked the rewards that children earned through their own hard work. The probability of natural sharing is very low in infancy regardless of the item. According to parents’ reports in interviews, naturalistic sharing occurs at 9 months of age (Ziv and Sommerville, 2017). In the laboratory, infants at 15 and 18 months of age were able to engage in sharing behavior after being presented with a series of progressively more explicit cues (Schmidt and Sommerville, 2011; Brownell et al., 2013; Ziv and Sommerville, 2017). Studies found that preschool children are more willing to share things that are occasionally gained (Wang et al., 2005; Liu et al., 2013). Another study found that preschoolers shared prizes they earned through hard work the most, followed by their favorite toys, and least of all occasionally gained food (Li and Zhao, 2008). This study may be inconsistent with others may be that everything occasionally gained is plasticine, and the items accidentally obtained are small pieces of food. It is possible that different types of resources may entail different levels of attraction to children. For another, it may be that toys are not shared in the same way as food. Therefore, the resource types should be unified in future sharing studies.

Social reputation relates to how far children are willing to make a reasonable allocation of resources in the name of equity and represent prosocial sharing that meets social expectations. In the distribution situation, children’s social reputation indicates that when children realize that others may judge their distribution behavior, they adjust this behavior to behave more fairly to obtain a positive evaluation from others.

Many studies have shown that 5-year-old children are more generous in the presence of peers than when no one is present. When they are with different people, they make different allocation decisions (Dunham et al., 2011; Engelmann et al., 2012; Leimgruber et al., 2012). Children aged 6–8 years may be more concerned with their social reputation, making it more likely that they will behave fairly when their peers are present or when experimenters can learn of their choices. However, if the distribution that they give will not be found by others, the originally fair children may become unfair. In other words, the fair distribution is partly due to the children’s desire to appear fair in front of others (Shaw et al., 2014). Children aged 6–9 are more likely to accept an advantageous distribution if their peers are unaware of their advantages (McAuliffe et al., 2020). The results of these studies show that even if children have learned fair norms, internalized norms may also be strategically used in social situations that can improve their reputation. Social reputation concerns can narrow the knowledge and behavior gap in fair distribution among children.

Children’s concern for their social reputation can affect their sharing behavior in different sharing situations. In prosocial research, an individual’s reputation refers to others’ evaluation of his or her prosocial ability and motivation, such as whether others consider that he or she often treats others generously (Engelmann and Rapp, 2018). Children share more resources when they are aware of the presence of the recipient or other observers than when they are not; that is, children are more generous when they realize that their behavior is observed by others (Leimgruber et al., 2012; Sampaio and Neto Pires, 2015). In addition, because 5-year-olds are concerned about their reputation within the in-group, they tend to share more resources when observed by members of their in-group (Engelmann et al., 2013). More recently, study found that 5- to 9-year-old children’s sharing with in- and out-group members was affected by reputation in all groups (Yazdi et al., 2020). In conclusion, children’s attention to their reputation can affect their generosity in the context of prosocial sharing.

Social distance reflects the level and degree of closeness or alienation between people and groups. In one study, children aged 3–6 gave significantly more stickers or candy to their friends than to unfamiliar children whom they have never met (Yu et al., 2016). In the event of conflict between social relationships and contributions to allocation, children younger than seven decide based on social relationship. They adjust these allocation decisions in relation to the size of the recipient’s contribution (Zhang, 2020). At the group level, social distance affects individuals’ response to the unfair behavior of in- and out-group members, and individuals show in-group preferences even if in-group members violate the distribution principle (Zhang and Zhao, 2018). Blake generally explains these findings as indicating a social distance effect, which means that individuals can give more resources to recipients who are more closely related to them (Charness and Gneezy, 2008; Wu et al., 2011; Blake, 2018).

Children will allocate different amounts of resources to different recipients in the process of sharing according to the closeness of the relationship with the recipients. Preschool children aged 3–6 years share more rewards with their friends than non-friends and strangers (Vonk et al., 2020). In another study, in the exploration of whether preschool children choose to share with friends out of reciprocity, the researchers found that there were no differences between 3- and 5-year-olds in giving to friends with and without reciprocity, which shows that children’s preference to share with friends is independent of reciprocity (Lenz and Paulus, 2021). More studies are needed to explore the specific effects of social distance on children’s prosocial sharing.

The development of individual social behavior cannot be separated from the social cultural environment. Cross-cultural study of distribution indicates that advantageous inequity aversion varies from culture to culture. In some cultures, advantageous inequity aversion appears in middle childhood, but it not in others (Blake et al., 2015). When a quantity of items presented cannot be distributed equally, children would rather throw away some items than distribute them unfairly. However, unlike American children, Ugandan children tend to allocate resources unfairly rather than throw away extra resources (Paulus, 2015). Moreover, in Uganda, preschool and primary school children show a high level of generosity independent of social relationships (Scharpf et al., 2016). When recipients are different in wealth and contribution, children from individualistic cultures are more likely than those from collectivist cultures to favor fair distribution (more to the poor and to those with greater merit) than equal distribution. When recipients differ in degrees of injury, children from more collectivist culture tend to allocate more resources to more injured recipients than children from more individualistic cultures (Huppert et al., 2019). Recent studies have found that the role of merit in distribution seems to be different across cultures. Compared with Kenyan children, Chinese and German children selectively allocate resources to individuals who have more work. When friendship and merit are opposed, in all three cultures, children tend to share equally between friends who contribute less and less familiar people who contribute more (Engelmann et al., 2021). These results indicated that both commonality and individuality factor into individual equity in different cultures, which illustrates the significance of cross-cultural research in understanding the development of human distribution equity.

There have been few studies on the impact of social culture on sharing. Previous studies have shown that Asian children are more likely to share spontaneously and less likely to share passively (Rao and Stewart, 1999). Children in collectivist cultures tend to live in communities where harmonious interaction is highly valued, and they are more likely to share with their peers than children in individualistic cultures are (Stewart and McBride-Chang, 2000). However, a study on the sharing behavior of nearly 2,500 children aged 3–12 years from 12 countries on five continents did not find the expected significant differences between children from collectivist and from individualist countries (Samek et al., 2020). Therefore, more research is needed to determine whether social culture has an impact on children’s prosocial sharing behavior and internal mechanisms.