Do infants detect indirect reciprocity?

Core Moral Concepts and the Sense of Fairness in Human Infants

We review recent experimental studies relevant to assess the proposal that human infants possess a sense of fairness that relies on sociomoral knowledge. We propose that this knowledge may include a core concept of justice with four foundational aspects: impartiality, agency, obligatoriness and conflicting claims. Infants' and toddlers' looking times, manual preferences and spontaneous actions provide some evidence for the first three features. Very early-emerging sociomoral evaluations and expectations about resource distributions show that infants process morally relevant information about distributors and recipients, suggesting that they are sensitive to the agency and impartiality constraints. Early evaluations appear to be linked to third-party expressions of praise or admonishment and to the deliverance of rewards and punishment, providing initial support for the obligatoriness constraint. More work is needed to investigate the sensitivity to conflicting claims, to assess the universality of early emerging evaluation skills and to show how core concepts relate to the development of explicit judgments and beliefs about duties and rights.

Understanding a Third-Party Communicative Situation in Korean-Learning Infants

The present study tested 14-month-old monolingual infants (N = 64, 52% female, 75% Korean, and 25% American) in a looking-time task adapted from previous referent identification research. In three experiments, Korean-learning infants watched a speaker, who could only see one of two identical balls, ask a recipient, "gong jom jul-lae?" ("Will you give me Ø ball?" because Korean lacks an article system). They expected the recipient to reach for the ball visible to the speaker, but not the one hidden from her, only when the speaker was introduced separately to facilitate perspective-taking. Korean infants were also found to hold these expectations when the speaker said, "jeo gong jom jul-lae?" ("Will you give me that ball?"), presumably because the added demonstrative "jeo" rendered the speech more informative. A group of American English-learning infants performed similarly, but not as robustly as did their Korean peers, when the speaker requested "Give me that ball." These findings shed new light on how infants use their emergent perspective-taking and language skills to interpret a speaker's intended referent and expand the previous focus on English-learning infants.

11-month-olds recognize the teacher-student relationship

Understanding how preverbal infants perceive and differentiate the roles of teachers and students can provide profound insights into the early stages of human learning and cognition. We thus developed a paradigm based on the task order and the interactive position to determine if infants understand teacher-student relationships. Five experiments (N = 104), reveal that, after watching the teacher agent instruct the student agent from failure to success, 11-month-old infants looked at the teacher for a longer time when they watched a new naïve agent seek information in a new ambiguous scenario. Three additional control experiments excluded alternative interpretations of infants' selective looking, suggesting that agents' order-related actions influenced infants' identification. Another control experiment demonstrated the importance of the position when the teacher and the student had interactive exchanges. These findings indicate that preverbal infants can recognize the teacher-student relationship, which is crucial to accessing effective information in early life.

Infants expect some degree of positive and negative reciprocity between strangers

Social scientists from different disciplines have long argued that direct reciprocity plays an important role in regulating social interactions between unrelated individuals. Here, we examine whether 15-month-old infants (N = 160) already expect direct positive and negative reciprocity between strangers. In violation-of-expectation experiments, infants watch successive interactions between two strangers we refer to as agent1 and agent2. After agent1 acts positively toward agent2, infants are surprised if agent2 acts negatively toward agent1 in a new context. Similarly, after agent1 acts negatively toward agent2, infants are surprised if agent2 acts positively toward agent1 in a new context. Both responses are eliminated when agent2's actions are not knowingly directed at agent1. Additional results indicate that infants view it as acceptable for agent2 either to respond in kind to agent1 or to not engage with agent1 further. By 15 months of age, infants thus already expect a modicum of reciprocity between strangers: Initial positive or negative actions are expected to set broad limits on reciprocal actions. This research adds weight to long-standing claims that direct reciprocity helps regulate interactions between unrelated individuals and, as such, is likely to depend on psychological systems that have evolved to support reciprocal reasoning and behavior.

The Cognitive Architecture of Infant Attachment

Meta-analytic evidence indicates that the quality of the attachment relationship that infants establish with their primary caregiver has enduring significance for socioemotional and cognitive outcomes. However, the mechanisms by which early attachment experiences contribute to subsequent development remain underspecified. According to attachment theory, early attachment experiences become embodied in the form of cognitive-affective representations, referred to as internal working models (IWMs), that guide future behavior. Little is known, however, about the cognitive architecture of IWMs in infancy. In this article, we discuss significant advances made in the field of infant cognitive development and propose that leveraging insights from this research has the potential to fundamentally shape our understanding of the cognitive architecture of attachment representations in infancy. We also propose that the integration of attachment research into cognitive research can shed light on the role of early experiences, individual differences, and stability and change in infant cognition, as well as open new routes of investigation in cognitive studies, which will further our understanding of human knowledge. We provide recommendations for future research throughout the article and conclude by using our collaborative research as an example.

No one is going to recess: How children evaluate collective and targeted punishment

This study examined children's responses to targeted and collective punishment. Thirty-six 4-5-year-olds and 36 6-7-year-olds (36 females; 54 White; data collected 2018-2019 in the United States) experienced three classroom punishment situations: Targeted (only transgressing student punished), Collective (one student transgressed, all students punished), and Baseline (all students transgressed, all punished). The older children evaluated collective punishment as less fair than targeted, whereas younger children evaluated both similarly. Across ages, children distributed fewer resources to teachers who administered collective than targeted punishment, and rated transgressors more negatively and distributed fewer resources to transgressors in Collective and Targeted than Baseline. These findings demonstrate children's increasing understanding of punishment and point to the potential impact of different forms of punishment on children's social lives.

Infants can use temporary or scant categorical information to individuate objects

In a standard individuation task, infants see two different objects emerge in alternation from behind a screen. If they can assign distinct categorical descriptors to the two objects, they expect to see both objects when the screen is lowered; if not, they have no expectation at all about what they will see (i.e., two objects, one object, or no object). Why is contrastive categorical information critical for success at this task? According to the kind account, infants must decide whether they are facing a single object with changing properties or two different objects with stable properties, and access to permanent, intrinsic, kind information for each object resolves this difficulty. According to the two-system account, however, contrastive categorical descriptors simply provide the object-file system with unique tags for individuating the two objects and for communicating about them with the physical-reasoning system. The two-system account thus predicts that any type of contrastive categorical information, however temporary or scant it may be, should induce success at the task. Two experiments examined this prediction. Experiment 1 tested 14-month-olds (N = 96) in a standard task using two objects that differed only in their featural properties. Infants succeeded at the task when the object-file system had access to contrastive temporary categorical descriptors derived from the objects' distinct causal roles in preceding support events (e.g., formerly a support, formerly a supportee). Experiment 2 tested 9-month-olds (N = 96) in a standard task using two objects infants this age typically encode as merely featurally distinct. Infants succeeded when the object-file system had access to scant categorical descriptors derived from the objects' prior inclusion in static arrays of similarly shaped objects (e.g., block-shaped objects, cylinder-shaped objects). These and control results support the two-system account's claim that in a standard task, contrastive categorical descriptors serve to provide the object-file system with unique tags for the two objects.

Reputation and reciprocity

Reputation and reciprocity are key mechanisms for cooperation in human societies, often going hand in hand to favor prosocial behavior over selfish actions. Here we review recent researches at the interface of physics and evolutionary game theory that explored these two mechanisms. We focus on image scoring as the bearer of reputation, as well as on various types of reciprocity, including direct, indirect, and network reciprocity. We review different definitions of reputation and reciprocity dynamics, and we show how these affect the evolution of cooperation in social dilemmas. We consider first-order, second-order, as well as higher-order models in well-mixed and structured populations, and we review experimental works that support and inform the results of mathematical modeling and simulations. We also provide a synthesis of the reviewed researches along with an outlook in terms of six directions that seem particularly promising to explore in the future.

Evaluations of pro-environmental behaviors by 7-month-old infants

Environmental morality is the foundation of a sustainable future, yet its ontogenetic origin remains unknown. In the present study, we asked whether 7-month-olds have a sense of 'environmental morality'. Infants' evaluations of two pro-environmental actions were assessed in both visual and reaching preferential tasks. In Experiment 1, the overt behavior of protecting (i.e., collecting artificial objects spread on a lawn) was compared with the action of harming the environment (i.e., by disregarding the objects). In Experiment 2, the covert behavior of protecting the environment (i.e., maintaining artificial objects inside a container) was compared with the action of harming the environment (i.e., littering the artificial objects on a lawn). The results showed infants' reaching preference for the agent who performed overt pro-environmental actions (Experiment 1), and no preference for the agent who performed covert pro-environmental actions (Experiment 2). These findings reveal a rudimentary ecological sense and suggest that infants require different abilities to evaluate overt impact-oriented and covert intend-oriented pro-environmental behaviors.

Age-dependent changes in intuitive and deliberative cooperation

Cooperation is one of the most advantageous strategies to have evolved in small- and large-scale human societies, often considered essential to their success or survival. We investigated how cooperation and the mechanisms influencing it change across the lifespan, by assessing cooperative choices from adolescence to old age (12-79 years, N = 382) forcing participants to decide either intuitively or deliberatively through the use of randomised time constraints. As determinants of these choices, we considered participants' level of altruism, their reciprocity expectations, their optimism, their desire to be socially accepted, and their attitude toward risk. We found that intuitive decision-making favours cooperation, but only from age 20 when a shift occurs: whereas in young adults, intuition favours cooperation, in adolescents it is reflection that favours cooperation. Participants' decisions were shown to be rooted in their expectations about other people's cooperative behaviour and influenced by individuals' level of optimism about their own future, revealing that the journey to the cooperative humans we become is shaped by reciprocity expectations and individual predispositions.

Intention-based evaluations of distributive actions by 4-month-olds

Four-month-olds' ability to consider the intentions of agents performing distributive actions was investigated in four experiments, using the Violation of Expectation paradigm (VoE) (Experiments 1-3) and the Preferential Looking paradigm (Experiment 4). In Experiment 1, infants were presented with two events showing two types of failed attempts to perform a distribution. In an attempt to distribute fairly, the distributor first tried to reach one of the recipients to deliver an apple, he failed, and then attempted to reach the other recipient to deliver a second apple and also failed. In an attempt to distribute unfairly, a different distributor tried unsuccessfully to bring resources always to the same recipient. Infants looked reliably longer at failed fair distribution events, suggesting that they did not just react to the actions outcomes and they attended to agents' intentions. Experiments 2 and 3 assessed alternative explanations based on perceptual factors or affiliative behaviors. In Experiment 4, during the test trials, infants were shown both distributors simultaneously and they preferred to look at the fair rather than at the unfair distributor. Overall, these findings reveal an early ability to take into account distributors' intentions and a preference for watching agents that tried to distribute resources fairly.

Preverbal infants' reactions to third-party punishments and rewards delivered toward fair and unfair agents

Rewarding individuals who distribute resources fairly and punishing those who distribute resources unfairly may be very important actions for fostering cooperation. This study investigated whether 9-month-olds have some expectations concerning punishments and rewards that follow distributive actions. Infants were shown simple animations and were tested using the violation-of-expectation paradigm. In Experiment 1, we found that infants looked longer when they saw a bystander delivering a corporal punishment to a 'fair distributor,' who distributed some windfall resources equally to the possible recipients, rather than to an 'unfair distributor,' who distributed the resources unequally. This pattern of looking times was reversed when, in Experiment 2, punishments were replaced with rewards. These findings suggest an early emergence of expectations about punishing and rewarding actions in third-party contexts, and they help to evaluate competing claims about the origins of a sense of fairness.

Socially evaluative contexts facilitate mentalizing

Our ability to understand others' minds stands at the foundation of human learning, communication, cooperation, and social life more broadly. Although humans' ability to mentalize has been well-studied throughout the cognitive sciences, little attention has been paid to whether and how mentalizing differs across contexts. Classic developmental studies have examined mentalizing within minimally social contexts, in which a single agent seeks a neutral inanimate object. Such object-directed acts may be common, but they are typically consequential only to the object-seeking agent themselves. Here, we review a host of indirect evidence suggesting that contexts providing the opportunity to evaluate prospective social partners may facilitate mentalizing across development. Our article calls on cognitive scientists to study mentalizing in contexts where it counts.

Infants infer third-party social dominance relationships based on visual access to intergroup conflict

During a conflict, having a greater number of allies than the opposition can improve one's success in a conflict. However, allies must be aware that has a conflict has occurred, and this is often influenced by what they are able to see. Here, we explored whether infants' assessment of social dominance is influenced by whether or not social allies have visual access to an episode of intergroup conflict. In Experiment 1, 9-12-month-olds only expected an agent to be socially dominant if their allies were able to witness the conflict. Experiment 2 provided further support for this finding, as infants did not expect an agent from a numerically larger group to be socially dominant when allies were unable to witness the conflict. Together, these results suggest that infants do not simply use a heuristic in which "numerically larger groups are always more dominant". Importantly, infants are able to incorporate social allies' ability to witness a conflict when predicting social dominance between groups.

Third-party punishment by preverbal infants

Third-party punishment of antisocial others is unique to humans and seems to be universal across cultures. However, its emergence in ontogeny remains unknown. We developed a participatory cognitive paradigm using gaze-contingency techniques, in which infants can use their gaze to affect agents displayed on a monitor. In this paradigm, fixation on an agent triggers the event of a stone crushing the agent. Throughout five experiments (total N = 120), we show that eight-month-old infants punished antisocial others. Specifically, infants increased their selective looks at the aggressor after watching aggressive interactions. Additionally, three control experiments excluded alternative interpretations of their selective gaze, suggesting that punishment-related decision-making influenced looking behaviour. These findings indicate that a disposition for third-party punishment of antisocial others emerges in early infancy and emphasize the importance of third-party punishment for human cooperation. This behavioural tendency may be a human trait acquired over the course of evolution.

Is Distributional Justice Equivalent to Prosocial Sharing in Children's Cognition?

Distribution and sharing are social preference behaviors supported and shaped by selection pressures, which express individuals' concern for the welfare of others. Distributive behavior results in distributive justice, which is at the core of moral justice. Sharing is a feature of the prosocial realm. The connotations of distribution and sharing are different, so the principles, research paradigms, and social functions of the two are also different. Three potential causes of confusion between the two in the current research on distribution and sharing are discussed. First, they share common factors in terms of individual cognition, situation, and social factors. Second, although they are conceptually different, prosocial sharing and distribution fairness sensitivity are mutually predictive in individual infants. Similarly, neural differences in preschoolers' perception of distribution fairness predict their subsequent sharing generosity. Finally, similar activation regions are relevant to distribution and sharing situations that need behavioral control on a neural basis.

Cross-cultural differences in early expectations about third party resource distribution

Research using non-verbal looking-time methods suggests that pre-verbal infants are able to detect inequality in third party resource allocations. However, nothing is known about the emergence of this capacity outside a very narrow Western context. We compared 12- to 20-month-old infants (N = 54) from one Western and two non-Western societies. Swedish infants confirmed the pattern from previous Western samples by looking longer at the unequal distribution, suggesting that they expected the resources to be distributed equally. Samburu infants looked longer at the equal distribution, suggesting an expectation of unequal distribution. The Kikuyu infants looked equally at both distributions, and did not show any specific exactions. These results suggest that expectations of equal distributions in third party allocations are affected by experience of cultural variations of distributive norms and social interaction early in development.

Adopted Utility Calculus: Origins of a Concept of Social Affiliation

To successfully navigate their social world, humans need to understand and map enduring relationships between people: Humans need a concept of social affiliation. Here I propose that the initial concept of social affiliation, available in infancy, is based on the extent to which one individual consistently takes on the goals and needs of another. This proposal grounds affiliation in intuitive psychology, as formalized in the naive-utility-calculus model. A concept of affiliation based on interpersonal utility adoption can account for findings from studies of infants' reasoning about imitation, similarity, helpful and fair individuals, "ritual" behaviors, and social groups without the need for additional innate mechanisms such as a coalitional psychology, moral sense, or general preference for similar others. I identify further tests of this proposal and also discuss how it is likely to be relevant to social reasoning and learning across the life span.

Infants' intention-based evaluations of distributive actions

Recent research revealed that infants attend to agents' intentions when they evaluate helping actions. The current study investigated whether infants also consider agents' intentions when they evaluate distributive actions. In Experiment 1, 9-month-old infants were first shown two failed attempts to perform a distribution. In the "failed equal distribution," the distributor first tried to reach one of the recipients to deliver an apple, failed, and then attempted to reach the other possible recipient to deliver a different apple and also failed. In the "failed unequal distribution," a different distributor always tried unsuccessfully to reach the same beneficiary. Then, in the test phase, infants were presented with the two distributors side by side, and infants' spontaneous preferential looking and reaching actions were recorded. We found a reliable preference for the equal distributor in both the visual and manual responses. Experiments 2 and 3 helped to rule out alternative explanations based on perceptual cues and affiliative biases. Overall, these findings suggest that infants' ability to evaluate distributive actions relies not only on the outcomes but also on the distributors' intentions.

The evolution of moral rules in a model of indirect reciprocity with private assessment

Moral rules allow humans to cooperate by indirect reciprocity. Yet, it is not clear which moral rules best implement indirect reciprocity and are favoured by natural selection. Previous studies either considered only public assessment, where individuals are deemed good or bad by all others, or compared a subset of possible strategies. Here we fill this gap by identifying which rules are evolutionary stable strategies (ESS) among all possible moral rules while considering private assessment. We develop an analytical model describing the frequency of long-term cooperation, determining when a strategy can be invaded by another. We show that there are numerous ESSs in absence of errors, which however cease to exist when errors are present. We identify the underlying properties of cooperative ESSs. Overall, this paper provides a first exhaustive evolutionary invasion analysis of moral rules considering private assessment. Moreover, this model is extendable to incorporate higher-order rules and other processes.

Can 5-month-old infants consider the perspective of a novel eyeless agent? New evidence for early mentalistic reasoning

Is early reasoning about an agent's knowledge best characterized by a mentalistic stance, a teleological stance, or both? In this research, 5-month-old infants (N = 64, 50% female, 83% White) saw a novel eyeless agent consistently approach object-A as opposed to object-B. Although infants could always see both objects, a screen separated object-B from the agent. When object-B protruded above the screen, infants interpreted the agent's actions as revealing a preference for object-A over object-B. When object-B did not protrude above the screen, however, infants refrained from attributing such a preference: Consistent with mentalistic accounts, they reasoned that the agent's representation of the scene did not include object-B, and they used the agent's incomplete representation, non-egocentrically, to interpret its actions.

Toddlers draw broad negative inferences from wrongdoers' moral violations

By 2 y of age, children possess expectations about several different moral principles. Building on these results, we asked whether children who observed a wrongdoer violate a principle would draw negative inferences from this violation about how the wrongdoer was likely to behave in other contexts. In four experiments, 25-mo-old toddlers (n = 152) first saw a wrongdoer harm a protagonist. When toddlers judged the wrongdoer's behavior to violate the principle of ingroup support or harm avoidance, they did not find it unexpected if the wrongdoer next violated the principle of fairness by dividing resources unfairly between two other protagonists (Exps. 2 and 3), but they did find it unexpected if the wrongdoer next acted generously by giving another protagonist most of a resource to be shared between them (Exp. 4). When toddlers did not construe the wrongdoer's harmful behavior as a moral violation, these responses reversed: They found it unexpected if the wrongdoer next acted unfairly (Exp. 1) but not if the wrongdoer next acted generously (Exp. 4). Detecting a moral violation thus lowered toddlers' assessment of the wrongdoer's moral character and brought down their expectations concerning the likelihood that the wrongdoer would perform: 1) obligatory actions required by other principles and 2) supererogatory or virtuous actions not required by the principles. Together, these findings expand our understanding of how young children evaluate others' moral characters, and they reveal how these evaluations, in turn, enable children to form sophisticated expectations about others' behavior in new contexts.

Toddlers' expectations of third-party punishments and rewards following an act of aggression

Rewarding someone who defends the victim of an unjust aggression and punishing someone who chose not to defend her may be very important acts of reciprocation in social life. This study investigates whether 21-month-olds have some expectations concerning such punishing and rewarding actions. Infants were shown simple puppet shows and were tested using the violation-of-expectation paradigm. In Experiment 1, we found that infants looked longer when they saw a bystander puppet punishing the puppet who defended the victim rather than the puppet who did not defend her. This pattern of looking times was reversed when the punishing action was replaced with a rewarding action (Experiment 2). These findings reveal early-emerging expectations about punitive and reward motivations in third-party contexts, and provide some support for theoretical claims about the hardwiring of the human mind for cooperation and prosociality.

I'm not a little kid anymore! Reciprocal social influence in child-adult interaction

Human decisions are often influenced by others' opinions. This process is regulated by social norms: for instance, we tend to reciprocate the consideration received from others, independently of their reliability as information sources. Nonetheless, no study to date has investigated whether and how reciprocity modulates social influence in child-adult interaction. We tested 6-, 8- and 10-year-old children in a novel joint perceptual task. A child and an adult experimenter made perceptual estimates and then took turns in making a final decision, choosing between their own and partner's response. We manipulated the final choices of the adult partner, who in one condition chose often the child's estimates, whereas in another condition tended to confirm her own response. Results reveal that 10-year-old children reciprocated the consideration received from the partner, increasing their level of conformity to the adult's judgements when the partner had shown high consideration towards them. At the same time, 10-year-old children employed more elaborate decision criteria in choosing when trusting the adult partner compared to younger children and did not show egocentric biases in their final decisions. Our results shed light on the development of the cognitive and normative mechanisms modulating reciprocal social influence in child-adult interaction.

Toddlers' interventions toward fair and unfair individuals

Cooperative societies rely on reward and punishment for norm enforcement. We examined the developmental origin of these interventions in the context of distributive fairness: past research has shown that infants expect resources to be distributed fairly, prefer to interact with fair distributors, and evaluate others based on their fair and unfair resource allocations. In order to determine whether infants would intervene in third-party resource distributions by use of reward and punishment we developed a novel task. Sixteen-month-old infants were taught that one side of a touch screen produces reward (vocal statements expressing praise; giving a cookie), whereas the other side produces punishment when touched (vocal statements expressing admonishment; taking away a cookie). After watching videos in which one actor distributed resources fairly and another actor distributed resources unfairly, participants' screen touches on the reward and punishment panels while the fair and unfair distributors appeared on screen were recorded. Infants touched the reward side significantly more than the punishment side when presented with the fair distributor but touched the screen sides equally when the unfair distributor was shown. Control experiments revealed no evidence of reward or punishment when infants saw food items they liked and disliked, or individuals uninvolved in the resource distribution events. These results provide the earliest evidence that infants are able to spontaneously intervene in socio-moral situations by rewarding positive actions.

Five-month-old infants attribute inferences based on general knowledge to agents

To make sense of others' actions, we generally consider what information is available to them. This information may come from different sources, including perception and inference. Like adults, young infants track what information agents can obtain through perception: If an agent directly observes an event, for example, young infants expect the agent to have information about it. However, no investigation has yet examined whether young infants also track what information agents can obtain through inference, by bringing to bear relevant general knowledge. Building on the finding that by 4 months of age most infants have acquired the physical rule that wide objects can fit into wide containers but not narrow containers, we asked whether 5-month-olds would expect an agent who was searching for a wide toy hidden in her absence to reach for a wide box as opposed to a narrow box. Infants looked significantly longer when the agent selected the narrow box, suggesting that they expected her (a) to share the physical knowledge that wide objects can fit only into wide containers and (b) to infer that the wide toy must be hidden in the wide box. Three additional conditions supported this interpretation. Together, these results cast doubt on two-system accounts of early psychological reasoning, which claim that infants' early-developing system is too inflexible and encapsulated to integrate inputs from other cognitive processes, such as physical reasoning. Instead, the results support one-system accounts and provide new evidence that young infants' burgeoning psychological-reasoning system is qualitatively similar to that of older children and adults.

The Origins of Intergroup Resource Inequality Influence Children's Decision to Perpetuate or Rectify Inequality

Previous studies have explored children's intergroup resource allocation in the context of preexisting intergroup resource inequality. However, resource inequality between social groups often originates from different factors. This study explored the role of the origins of resource inequality on children's intergroup resource allocations. In experiment 1, when there was no explicit origin of the intergroup inequality, children of different ages mainly allocated resources in an equal way and 5- to 6-year-olds showed ingroup bias. In experiment 2, we examined the influence of different origins of intergroup inequality and found that 5- to 6-year-olds perpetuated intergroup inequality when resource inequality was based on either a structural (regional disparity) or an internal factor (difference in performance). However, 10- to 11-year-olds rectified inequality or allocated equally when intergroup inequality was based on regional disparity and perpetuated resource inequality when intergroup inequality was based on performance difference. The origins of inequality appear to play an important role in children's intergroup resource allocations, and older children can distinguish different origins of intergroup inequality in resource allocation.

Infants Consider the Distributor's Intentions in Resource Allocation

Recent experimental studies suggest that preverbal infants are able to evaluate agents on the basis of their distributive actions. Here we asked whether such evaluations are based on infants' understanding of the distributors' intentions, or only the outcome of their actions. Ten-month-old infants observed animated movies of unequal resource allocations by distributors who attempted but failed to distribute resources equally or unequally between two individuals. We found that infants attended longer to the test event showing a third agent approaching a distributor who was unable to make an unequal distribution, compared to the test event where the third agent approached a distributor who was unable to make an equal distribution of resources. Our results suggest that infants' ability to encode distributive actions goes beyond an analysis of the outcome of these actions, by including the intentions of the distributors whose actions lead to these outcomes.

Moral judgements of fairness-related actions are flexibly updated to account for contextual information

In everyday life we are constantly updating our moral judgements as we learn new information. However, this judgement updating process has not been systematically studied. We investigated how people update their moral judgements of fairness-related actions of others after receiving contextual information regarding the deservingness of the action recipient. Participants (N = 313) observed a virtual ‘Decision-maker’ share a portion of $10 with a virtual ‘Receiver’. Participants were aware that the Decision-maker made these choices knowing the Receiver’s previous offer to another person. Participants first made a context-absent judgement of the Decision-maker’s offer to the Receiver, and then a subsequent context-present judgement of the same offer after learning the Receiver’s previous offer. This sequence was repeated for varying dollar values of Decision-makers’ and Receivers’ offers. Patterns of judgements varied across individuals and were interpretable in relation to moral norms. Most participants flexibly switched from relying on context-independent norms (generosity, equality) to related, context-dependent norms (relative generosity, indirect reciprocity) as they integrated contextual information. Judgement of low offers varied across individuals, with a substantial minority of participants withholding their context-absent judgements of selfishness, and another minority that was lenient towards selfishness across both judgements. Our paradigm provides a novel framework for investigating how moral judgements evolve in real time as people learn more information about a given situation.

Knowledge before Belief

Research on the capacity to understand others' minds has tended to focus on representations of beliefs, which are widely taken to be among the most central and basic theory of mind representations. Representations of knowledge, by contrast, have received comparatively little attention and have often been understood as depending on prior representations of belief. After all, how could one represent someone as knowing something if one doesn't even represent them as believing it? Drawing on a wide range of methods across cognitive science, we ask whether belief or knowledge is the more basic kind of representation. The evidence indicates that non-human primates attribute knowledge but not belief, that knowledge representations arise earlier in human development than belief representations, that the capacity to represent knowledge may remain intact in patient populations even when belief representation is disrupted, that knowledge (but not belief) attributions are likely automatic, and that explicit knowledge attributions are made more quickly than equivalent belief attributions. Critically, the theory of mind representations uncovered by these various methods exhibit a set of signature features clearly indicative of knowledge: they are not modality-specific, they are factive, they are not just true belief, and they allow for representations of egocentric ignorance. We argue that these signature features elucidate the primary function of knowledge representation: facilitating learning from others about the external world. This suggests a new way of understanding theory of mind-one that is focused on understanding others' minds in relation to the actual world, rather than independent from it.

Paying it back and forward: The impact of experiencing and observing others' sharing and stinginess on preschoolers' own sharing behavior and expectations

Recent research suggests that children's sharing behavior is affected by experiencing or observing others' sharing. These effects have been studied within research on the development of reciprocity and the effects of social modeling. In the current study, direct and indirect types of reciprocity and social modeling were assessed in 3- to 6-year-old children in three experiments (overall N = 382). In each experiment, we explored whether negative and positive social behavior were similarly paid back and forward in each of the different types of reciprocity. Moreover, we assessed the extent to which children reciprocated toward the protagonist who had performed the actual behavior and toward a neutral other. In Experiment 1, children experienced another's sharing behavior as recipients and could then allocate resources to this character and a neutral other. In Experiment 2, children observed another's sharing behavior and could then allocate resources to this character and a neutral other. In Experiment 3, children were asked to predict another protagonist's sharing in the same context as in Experiment 1. Overall, children treated the protagonist and the neutral other similarly and predicted others to do the same. Yet, they were more likely to reciprocate negative acts in indirect types of reciprocity. The results are interpreted with respect to the impact of observational learning and representational development on children's social behavior.

First steps toward an understanding of procedural fairness

In four experiments, we tested whether 20-month-old infants are sensitive to violations of procedural impartiality. Participants were shown videos in which help was provided in two different ways. A main character provided help to two other agents either impartially, by helping them at the same time, or in a biased way, by helping one agent almost immediately while the other after a longer delay. Infants looked reliably longer at the biased than at the unbiased help scenarios despite the fact that in both scenarios help was provided to each beneficiary. This suggests that human infants can attend to departures from impartiality and, in their second year, they already show an initial understanding of procedural fairness.

Paying it forward: The development and underlying mechanisms of upstream reciprocity

Two studies investigated the development and motivations underlying children's upstream reciprocity. In Study 1, 3- and 4-year-olds (n = 40 per age group) received or did not receive help while playing a game. Subsequently, children could share stickers with a new child. The 4-year-olds, but not the 3-year-olds, showed evidence of upstream reciprocity: Those who had received help were more generous toward the new child. Study 2 (N = 46) replicated the results with 4-year-olds and found evidence for a gratitude-like motivation underlying the upstream reciprocity: Children who received help evaluated the benefactor more positively, and positive evaluations of the benefactor correlated with children's upstream reciprocity. Thus, upstream reciprocity emerges by 4 years of age and may already be motivated by a gratitude-like mechanism.

Normative foundations of reciprocity in preschoolers

Reciprocity has been suggested to represent a crucial normative principle for humans. The current study aimed to investigate the normative foundations of reciprocity and the development of a reciprocity norm in young children. To this end, we presented 3- to 6-year-olds with three conditions. In one condition, a protagonist reciprocated sharing a large proportion of resources. In another condition, a protagonist reciprocated sharing a small proportion of resources. In a third condition, a protagonist did not reciprocate sharing a large proportion by giving rather few resources and, thus, violated a reciprocity norm. Results show that 5- and 6-year-olds endorse compliance with a reciprocity norm, which is reflected in their evaluations of the protagonists and their spontaneous verbal affirmation of reciprocal behavior. In contrast, 3- and 4-year-olds exclusively valued general prosociality, neglecting reciprocity. This indicates that children acquire a norm of reciprocity during the course of the preschool period.

Preschoolers consider (absent) others when choosing a distribution procedure

This study investigated how the presence of others and anticipated distributions for self influence children’s fairness-related decisions in two different socio-moral contexts. In the first part, three- and five-year-old children (N = 120) decided between a fair and an unfair wheel of fortune to allocate resources (procedural justice). In the second part, they directly chose between two distributions of resources (distributive justice). While making a decision, each child was either observed by the affected group members (public), alone (private), or no others were introduced (non-social control). Children choose the fair option more often when others were affected (independently of their presence) only in the procedural justice task. These results suggest that using a fair procedure to distribute resources allows young preschoolers to overcome selfish tendencies.

What evidence is required to determine whether infants infer the kinship of third parties? A commentary on Spokes and Spelke (2017)

Research into the cognitive capacities of infants has revealed a rich assortment of competencies that help to structure inferences across multiple content domains. Despite these advances, researchers have paid relatively little attention to a domain crucial to social life: kinship. One recent exception is a set of studies by Spokes and Spelke (2017), who report evidence that 15 to 18-month-old infants expect social affiliation between two babies receiving care from the same adult. The experiments reported by Spokes and Spelke raise the key question of whether infants harbor intuitions regarding kinship-and provide tantalizing hints that they do. But determining whether the infant inferences found in these experiments in fact do implicate a kin-specific psychology is not straightforward, as kinship and social group membership overlap. Researchers need a set of criteria for ascertaining whether individuals (preverbal infants in particular but also children and adults alike) infer kinship-the likely genetic relatedness-between agents based on interactions with a common 3rd party and then use this information to guide expectations of behavior. Here, we consider the nature of evidence that would be needed to establish in principle that infants make inferences specific to kinship. In doing so, we link the developmental literature on infant social cognition to adult kin detection research, which has previously grappled with the question of what evidentiary standards reasonably establish the presence of kin-specific inferences. In light of prior empirical and theoretical work, we advance four criteria for establishing the presence of tacit knowledge of kinship, assess the extent to which the studies presented by S&S meet these criteria, and use the criteria to inform and spark directions for future research.