Normative foundations of reciprocity in preschoolers

Journal of Experimental Child Psychology 188 (2019) 104693

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Normative foundations of reciprocity in preschoolers Monika Wörle ⇑, Markus Paulus Developmental Psychology, Ludwig-Maximilians-Universität München, 80802 Munich, Germany

a r t i c l e

i n f o

Article history: Received 27 November 2018 Revised 2 August 2019 9 August 2019 Available online 16 September 2019 Keywords: Reciprocity norm Normativity Moral development Fairness Social development Preschool children

a b s t r a c t 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. Ó 2019 Elsevier Inc. All rights reserved.

Introduction Direct reciprocity—the tendency to repay positive and negative behavior to others—is a powerful mechanism to establish cooperation among humans and has been considered an evolutionary advantageous strategy (Trivers, 1971). Studies applying game-theoretic models found that on a group level contingent reciprocal behavior gives rise to a superior level of cooperation (Axelrod & Hamilton, ⇑ Corresponding author. E-mail address: [email protected] (M. Wörle). https://doi.org/10.1016/j.jecp.2019.104693 0022-0965/Ó 2019 Elsevier Inc. All rights reserved.

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1981). Consequently, acting reciprocally leads to long-term benefits for individuals. Indeed, human adults readily show reciprocal behavior when interacting with others (e.g., Gurven, 2006). Given the widely recognized importance of reciprocity for human social behavior, influential theories have even suggested that reciprocity represents a universal normative principle for humans (Gouldner, 1960). That is, it has been proposed that humans might conceive of reciprocal behavior as being normatively required. This theoretical notion is supported by empirical findings showing that people experience negative feelings such as guilt when they do not have the opportunity to reciprocate (e.g., Shumaker & Jackson, 1979). Moreover, people adhere to the principle of reciprocity even when it is in conflict with their self-interest (Gallucci & Perugini, 2000) or when their reciprocal act remains unnoticed by the recipient (Burger, Sanchez, Imberi, & Grande, 2009; Whatley, Webster, Smith, & Rhodes, 1999). These results are in line with the view that reciprocity is a norm. The current study was designed to examine the early development of a norm of reciprocity in young children. Early roots of general prosociality and reciprocity Reciprocity might play an important role, even in young children, because it represents the basis of many social interactions and it stabilizes social relationships. For example, turn taking in conversations and give-and-take scenarios are social interactions that are structured by reciprocity. Thus, on a practical level, in their everyday interactions and play, even preschoolers are confronted with reciprocity. Moreover, reciprocity plays a role in initiating and maintaining friendships. Sharing and interpersonal resource allocation contexts might be crucial for the early emergence of contingent reciprocity among individuals. This is because reciprocity prevents being exploited by giving away all resources without receiving anything in return. Indeed, reciprocity arises in a sharing context before it does in a helping context (Warneken & Tomasello, 2013). Therefore, an understanding of the principle of reciprocity, especially in sharing and resource allocation contexts, might be part of adequate social functioning from early on. Recently, it has been revealed that sensitivity for the principle of reciprocity might emerge much earlier in human ontogeny than classical theories (Piaget, 1932) and previous empirical research (e.g., Damon, 1977) have assumed. It has been suggested that by the end of the first year of life, infants have some intuitive understanding of reciprocity, as indicated by longer looking times at nonreciprocal events than at reciprocal events and a preference for reciprocal agents over nonreciprocal agents (e.g., Hamlin, Wynn, Bloom, & Mahajan, 2011; Meristo & Surian, 2013). In forced-choice scenarios, children in their second year of life already showed selective helping behavior toward partners who have demonstrated prosocial behavior (Van de Vondervoort, Aknin, Kushnir, Slevinsky, & Hamlin, 2018) or showed an inclination to distribute resources fairly (Burns & Sommerville, 2014). Yet, in other studies, such selectivity on the behavioral level was not found before 2 years of age (Dahl, Schuck, & Campos, 2013) or even 4 years of age (Kenward & Dahl, 2011). Thus, ‘‘partner choice” (i.e., the selection of social partners as targets of prosocial behavior; Baumard, André, & Sperber, 2013) seems to depend on a variety of contextual factors and seems to emerge during toddlerhood or the early preschool years (cf. Kuhlmeier, Dunfield, & O’Neill, 2014). In contrast, ‘‘partner control” (cf. Bull & Rice, 1991) refers to the ability to consistently match one’s behavior with a partner’s behavior in a repeated interaction (also known as contingent reciprocity or direct reciprocity). Practically, this ability helps to foster trust and cooperation and to prevent free riding by punishing defectors. Developmental studies provide consistent evidence that in sharing contexts children first show contingent reciprocal behavior between 3 and 5 years of age (Levitt, Weber, Clark, & McDonnell, 1985; Warneken & Tomasello, 2013) but not at 2 years of age (Sebastián-Enesco, Hernández-Lloreda, & Colmenares, 2013). In a theoretical integration of current work, Warneken and Tomasello (2013) presented a model on the early emergence of contingent reciprocity. In their ‘‘reciprocity is secondary” model, they suggested that children initially show a spontaneous tendency to help and share that is at first unaffected by reciprocal concerns. Around 3 years of age, this tendency gets shaped by a consideration of reciprocity. Thereby, children become selective and direct their prosocial behavior specifically toward those who have been or could be prosocial to them. This model provides a valuable framework to understand the early emergence of contingent reciprocal behavior (‘‘partner control”) even though it must be recognized that first

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instances of reciprocity do not mark the endpoint of development. Thus, the ‘‘reciprocity is secondary” model suggests a developmental shift from a rather unspecific inclination to act prosocially toward others to a tendency for contingent reciprocal behavior from 3 years of age onward. Taken together, children show an understanding of reciprocity and first instances of reciprocal behavior at a young age. If young children show behavioral manifestations of reciprocity and seem to react surprised at nonreciprocal behavior, this opens up the possibility (yet does not provide unequivocal evidence) for an early manifestation of a reciprocity norm, a norm that gratifications should be mutually exchanged (cf. Gouldner, 1960). In other words, because reciprocal behavior is fundamental for human social life and emerges early in development, it could be possible that already young children acquire normative expectations about reciprocity. Reciprocity: From strategic expectations to normative evaluations Although the infant studies point to the early developmental roots of humans’ concern with reciprocal behavior, they leave open the question of whether reciprocity is considered to be a norm. That is, it has been questioned whether the infant and toddler measures of visual or behavioral preferences allow for the unequivocal ascription of a normative stance (Dahl, 2014; Killen & Smetana, 2015; Rakoczy & Schmidt, 2013). The reported infant studies used forced-choice scenarios and so mainly assessed ‘‘partner choice,” which possibly facilitated children’s performance. Thus, the question regarding the precise developmental dynamics and, most interesting for our research question, a normative understanding of reciprocity requires further empirical examination. Another line of studies focuses on the development of strategic behavior. Some studies show that children at 3 and 4 years of age expect others to act reciprocally (Olson & Spelke, 2008), selectively demand resources from someone they have previously benefitted (Paulus, 2016), and strategically allocate more resources to someone who has the intention and resources to reciprocate (Kenward, Hellmer, Winter, & Eriksson, 2015). Sebastián-Enesco and Warneken (2015) found that, in a repeated interaction with another individual, children from 5 years of age consistently adapted their behavior to the behavior of their partner in anticipation of reciprocation. These studies, however, focused on strategic expectations rather than on normative evaluations of behavior. It remains an open question whether children’s expectations are based just on statistical regularities or whether they indicate normative understanding. Taken together, the reported findings of reciprocity on a behavioral level do not yield clear evidence of whether or not young children have a normative understanding of reciprocity. This is because reciprocal behavior can be motivated not only by norms but also by different factors such as emotions and strategic considerations (cf. Brownell, 2013; Martin & Olson, 2015; Paulus, 2014b). Thus, the current study aimed to investigate the presence of a reciprocity norm in young children and to explore its developmental trajectory. Thereby, reciprocity in interpersonal sharing situations was focused because this represents one important context in which the fairness principle is typically applied from early on. Behavioral indications of normativity The presence of a normative stance would be reflected most clearly in children’s explicit evaluations of behavior. This is because norms are used as a basis for evaluations (Rakoczy & Schmidt, 2013). If children evaluate an action based on a certain norm, it would provide evidence that they have acquired that norm. In studies on moral development, interview measures that assess children’s verbal evaluations are widely used, most often in the context of moral transgressions (e.g., Killen, Mulvey, Richardson, Jampol, & Woodward, 2011). Some contemporary studies investigated young children’s understanding of fairness norms by means of interview measures and could indeed show a normative understanding of equality (Cooley & Killen, 2015) as well as charity (Wörle & Paulus, 2018). Even children’s understanding of reciprocity has been investigated by means of interview measures (e.g., Damon, 1977). Berndt (1977) found that when reasoning about hypothetical scenarios, 6-year-olds, like adults, considered reciprocity as a causal and legitimate reason for sharing decisions even though they did not fully grasp the obligation to act reciprocally in a way that adults did. Such understanding

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was absent in younger children (Berndt, 1979). Yet, against the background of recent work that demonstrates an early onset of reciprocity on a behavioral level (e.g., Warneken & Tomasello, 2013), interview measures need to be rethought and systematically applied in younger age groups to uncover the early normative foundations of reciprocity. A more recent line of research uses children’s protest behavior as a measure of early normativity (e.g., Josephs, Kushnir, Gräfenhain, & Rakoczy, 2016; Rakoczy, Warneken, & Tomasello, 2008; Vaish, Missana, & Tomasello, 2011). If children verbally protest when they observe a norm violation from a third-party perspective, it indicates that they understand a critical feature of norms, namely their agent-neutral validity (see Rakoczy & Schmidt, 2013). Two studies provide evidence that children protest against the violation of the fairness norm of equal distribution at 3 years of age (Rakoczy, Kaufmann, & Lohse, 2016) and the violation of a charity norm at 5 years of age (Wörle & Paulus, 2018). The latter study reported that children also showed affirmation toward a norm-compliant agent, which can be explained as an attempt to maintain norm conformity. Thus, a measure of spontaneous protest and affirmation would be perfectly suitable to investigate the normative foundations of reciprocity in preschoolers. A third way to grasp children’s normative understanding is to assess their tendency to punish defectors and to reward people who have complied with a norm. Third-party punishment toward defectors can be seen as a mechanism to retain the integrity of a norm (Fehr & Fischbacher, 2004; Fehr, Fischbacher, & Gächter, 2002; Jensen, 2010). People indeed readily punish norm violations, and even children seem to understand that bad acts deserve punishment, whereas good acts should be rewarded (Karniol, 1978; Leman & Björnberg, 2010). Children make use of this option if they consider a norm of not harming others (Kenward & Dahl, 2011; Kenward & Östh, 2012, 2015; Vaish, Carpenter, & Tomasello, 2010) or fairness norms (McAuliffe, Jordan, & Warneken, 2015; Robbins & Rochat, 2011; Salali, Juda, & Henrich, 2015) being violated. All the above-mentioned measures, namely norm-based verbal evaluations, protest/affirmation, and third-party punishment, are suitable for studying the normative foundations of reciprocity in young children. More specifically, we aimed at examining the developmental trajectory of reciprocity on a normative level and at figuring out whether this trajectory equals the trajectory on the behavioral level as described in the ‘‘reciprocity is secondary” model (Warneken & Tomasello, 2013). Because in this model a general inclination to act prosocially gets complemented (not replaced) by reciprocal behavior during the course of development, we expected the same to be true on the normative level. Concretely spoken, we tested the idea that younger preschool children generally enforce prosocial behavior (without seeing reciprocity as normatively binding), whereas older preschool children also value reciprocity and consider it a norm that should be obeyed. The current study We investigated the development of a reciprocity norm in a sharing context. To this end, we presented children with three conditions in a within-participants design. In these three conditions, children could observe the sharing decisions of an agent whose behavior varied with respect to reciprocity and the total proportion of shared resources. In two conditions, an agent complied with a reciprocity norm by either reciprocating the sharing of a large proportion of resources or the sharing of a small proportion of resources. In a third condition, an agent violated a reciprocity norm by sharing only a small proportion of resources as a response to having received a large proportion of resources. We opted for this third condition because it is considered to capture the development of a reciprocity norm more sensitively than a condition in which sharing a small proportion is answered by sharing a large proportion. This is because we expected a reciprocity norm to complement, but not replace children’s appreciation of prosociality. Therefore, in a condition where an agent shares a large proportion in response to receiving a small proportion, children’s normative understanding of reciprocity might be overshadowed by the value they assign to prosociality. See Table 1 for a detailed overview of the different conditions. We hypothesized that a norm of reciprocity emerges by 5 years of age. One reason for this is that on the level of expectations children’s understanding of reciprocity seems to develop until 5 years of age (Sebastián-Enesco & Warneken, 2015). Because expectations can be seen as the conceptual basis of

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M. Wörle, M. Paulus / Journal of Experimental Child Psychology 188 (2019) 104693 Table 1 Number of items the initial allocator and protagonist shared as a function of condition. Initial allocator Condition Match-high Match-low Not matched

Trial Trial Trial Trial Trial Trial

1 2 1 2 1 2

Protagonist

Keep

Give

Keep

Give

1 0 2 3 1 0

2 3 1 0 2 3

1 0 2 3 2 3

2 3 1 0 1 0

normativity (Mead, 1934), we consider them to be a crucial prerequisite for the development of a normative understanding. Moreover, we focused on fairness norms that require the consideration of another person’s status and/or behavior (instead of just focusing on the way of splitting items, as is the case for a norm of equal distribution). Previous work on a norm of charity indicated that it emerges around 5 years of age (Wörle & Paulus, 2018). We also included a sample of younger preschool children in our study given that a number of studies provided evidence that behavioral contingent reciprocity (‘‘partner control”) emerges around 3 years of age (e.g., Warneken & Tomasello, 2013). Thus, we were specifically interested in whether there is a difference between the normative responses of 3- and 4-year-olds and 5- and 6-year-olds when the reciprocity norm is at stake. We hypothesized a developmental shift between these two age groups. Based on a ‘‘reciprocity is secondary” model, we also hypothesized that a norm for prosociality is complemented by a reciprocity norm during the course of development. Consequently, 3- and 4-yearolds were expected to just take into account the total amount of resources shared by the agents and, therefore, to react positively to the agent who shared a large proportion of resources and to react equally negatively to the agents who shared a small proportion of resources. In contrast, 5- and 6year-olds were expected to also consider reciprocity and, thus, demonstrate a normative understanding of reciprocity. Therefore, they were expected to react positively to the agents who shared reciprocally (and even most positively to the agent who did so by sharing a large proportion of resources) and to react negatively to the agent who did not share reciprocally. In sum, we expected 5- and 6-yearolds, but not 3- and 4-year-olds, to have a normative understanding of reciprocity. Method Participants The final sample consisted of 47 3- and 4-year-old children (M = 48.69 months, SD = 6.15, range = 36–59; 28 girls) and 45 5- and 6-year-old children (M = 69.75 months, SD = 6.43, range = 60–82; 15 girls). Two additional children were tested but not included in the final sample due to a loss of attention during the test situation (n = 1) and an experimental error (n = 1). Participants were typically developing children from day-care centers located in the surroundings of a large European city. Children were from heterogeneous socioeconomic backgrounds. The current study was noninvasive and strictly adhered to the legal requirements of the country in which it was conducted. The study was approved by the local ethics board. Informed written consent for participation was given by the children’s caregivers. Children provided verbal assent that they wanted to take part in the research. Materials The study consisted of three conditions. For each condition, we used a different pair of puppets: a protagonist and an initial allocator. We decided to do the current study with puppets because they have been successfully used in previous work with preschoolers (e.g., Kanngiesser & Warneken, 2012; Kenward & Dahl, 2011; Wörle & Paulus, 2018) and they allowed us to easily manipulate the

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behavior we presented to children. The protagonists were 65-cm-tall hand puppets that were played by the experimenter. The initial allocators were represented by portraits of another three puppets. (Portraits of) puppets were used for the initial allocators just like for the protagonists because we aimed to demonstrate interactions between peers. All puppets (protagonists and initial allocators) differed in hair color and clothing. The pairings of the puppets and assignments to conditions were counterbalanced. A ball, two puzzles, paper and pencils, and a wind-up toy were used for the warm-up trials. Stickers, colorful erasers, and gummy bears served as items. Two different types of items were used per condition: one type for the number the protagonist had received from the initial allocator and another type for the protagonist’s sharing. By not using the same type of item twice within one condition, we ensured that reciprocation could not result in an equal distribution. Thus, equality versus inequality unlikely affected children’s normative responses because all three conditions that we presented resulted in an unequal distribution of a certain type of items. Items were assigned to the conditions in a randomized fashion so that each type was received in one condition and shared in another condition. All protagonists and initial allocators got an envelope to store their items. For the punishment/rewarding, we provided participants with ‘‘tasty” (colorfully decorated) and ‘‘disgusting” (plain green) cookies. For the evaluation, we used a 4-point smiley scale. Design and procedure Children were tested individually in a quiet room. Experimental sessions were videotaped for later reliability coding. The study comprised three conditions that were presented to the participants after a warm-up and familiarization with the test material. All children saw all three conditions; the order of presentation of the conditions was counterbalanced. Each condition consisted of a sharing scenario in which a protagonist puppet was presented as the recipient of an initial allocator’s sharing. Subsequently, the protagonist had the opportunity to reciprocate, and children observed her acting out her sharing decision. Thereafter, a punishment/rewarding phase and an evaluation phase followed. It was manipulated whether the protagonist did or did not reciprocate the initial allocator’s behavior to see how this manipulation affects children’s responses toward the respective protagonist. In the following sections, the procedure is described in detail. Warm-up trials The experimenter introduced the protagonist puppets by their names, and each of them played ball with participants. Thereafter, one task-specific warm-up trial was administered with each protagonist individually in which she made a salient instrumental mistake. It was counterbalanced which protagonist did which of the following three trials: (a) puzzle, where the protagonist places a puzzle piece incorrectly; (b) drawing, where the protagonist tries to make a drawing with a broken pencil; and (c) wind-up toy, where the protagonist incorrectly moves a wind-up toy by hand. If participants did not intervene after a few seconds, they were prompted to do so. Thereby, their potential inhibition to criticize or correct the protagonists should be diminished. Familiarization After the warm-up trials, participants were familiarized with the tasty and disgusting cookies (procedure modified after Kenward & Östh, 2015). To this end, the experimenter tried one of each type and commented on its specific taste (‘‘delicious” vs. ‘‘worm-like”), displaying a matching facial expression. After this demonstration as well as at the end of the procedure, all participants were able to correctly identify the different cookie types. Moreover, following Killen et al. (2011), participants were familiarized with a 4-point smiley scale, ranging from very bad to very good, by means of a daily life example. After the familiarization, participants were presented with three conditions in a row. Sharing scenario Each condition started with a sharing scenario. In the sharing scenario, a protagonist puppet and a picture of an initial allocator were placed on the table. Then the experimenter told participants that the previous day the initial allocator had played a game in which she could share 6 items with the protagonist in two trials (3 items per trial). The experimenter reenacted the trials by twice putting 3 items

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next to the picture of the initial allocator and distributing them the way she said the initial allocator had done. Importantly, the amount the initial allocator was said to have shared was experimentally manipulated and differed between conditions (see Table 1 for an overview). In one condition we demonstrated a protagonist receiving a small proportion of resources (match-low condition), whereas in the other two conditions (match-high and not matched conditions) we showed protagonists receiving a high proportion of resources. In the match-low condition the initial allocator kept the majority of items for herself (2 of 3 in the first trial and 3 of 3 in the second trial), whereas in the match-high and not matched conditions the initial allocator shared the majority of items with the protagonist (2 of 3 in the first trial and 3 of 3 in the second trial). Across trials, the initial allocator’s behavior was consistent. Two different splits were used to highlight the initial allocators’ general inclination for sharing either a small or large proportion of her resources and to prevent the impression that she always used one particular way of splitting the items. After the sharing of the initial allocator, participants needed to indicate the number of items she had shared/kept for herself to test whether they had followed the demonstration. The experimenter corrected participants if they answered incorrectly. This was the case with two participants. Thereafter, the protagonist could in turn share items with the initial allocator and, thereby, decide how many items to give. This was the start of the crucial test phase of each trial. Just like the initial allocator before, the protagonist could distribute 6 items in two trials (3 items per trial). We used a different type of resource for the protagonist’s sharing than we had used for the initial allocator’s sharing. This is because we knew from previous research that children consider the relative wealth of recipients (Li, Spitzer, & Olson, 2014; Paulus, 2014a) and expect others to rectify inequalities by allocating more of the same resource to a recipient who has little (Wörle & Paulus, 2018). It was important to prevent participants from justifying the protagonists’ item distributions with the unequal endowment of items that had resulted from the initial allocator’s sharing. The protagonist split the items in the same proportions as the initial allocator had done (2–1 in the first trial and 3–0 in the second trial) and either consistently favored herself or the initial allocator across trials, depending on the condition. In the match-high condition, the protagonist who had received 5 of 6 items from the initial allocator paid the same amount of a different resource back to the partner and, thus, reciprocated sharing a high proportion of resources. In the match-low condition, the protagonist who had received only 1 of 6 items from the initial allocator paid the same amount of a different resource back to the partner and, thus, reciprocated sharing a small proportion of resources. In the not matched condition, the protagonist who had received 5 of 6 items from the initial allocator paid only 1 of 6 items back to the partner and, thus, did not reciprocate sharing a high proportion of resources but rather shared only a small proportion. Following previous research, the protagonists’ sharing followed a stepwise procedure with a 5-s pause between the steps in order to give participants the chance to intervene or protest. The steps were the following for each trial. In Step 1, the protagonist verbally stated the numbers of items she intended to share with the initial allocator and keep for herself while pointing to the respective person. In Step 2, the first step was repeated and also the protagonist moved the stated numbers of items a little bit in the direction of herself and the initial allocator. In Step 3, the protagonist distributed the items one by one, put them on her envelope and the initial allocator’s envelope, and verbally described her actions. Participants’ verbal comments on the protagonists’ sharing behavior (i.e., our main variable of interest during this phase of the protocol) were ignored, and the experimenter moved on. At the end of each sharing scenario, participants were asked check questions to test their memory of how many items the initial allocator had shared with the protagonist and of how many items the protagonist had in turn given to the initial allocator. Children who were not able to answer the check questions correctly were excluded from the analyses of those measures that are based on memory (punishment/rewarding and evaluation). Two participants were excluded.

Punishment/rewarding phase After the sharing scenario, a bowl with 3 tasty cookies and 3 disgusting cookies was handed out to participants. They were asked to allocate any number of cookies they wanted to the protagonist they had just observed in the sharing scenario. Participants were free to leave (all) cookies in the bowl.

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Evaluation phase First, participants needed to make a binary choice regarding the quality of the protagonist’s behavior (‘‘Do you think it was good or bad what [name of the puppet] did?”). Thereafter, they needed to refine their evaluation on the smiley scale (‘‘How good/bad do you think it was?”). Such a stepwise questioning procedure has been successfully used in other studies (Marsh, Ellis, & Craven, 2002). Moreover, children were asked to justify the evaluations they had given (‘‘Why do you think it was good/bad what [name of the protagonist] did?”) and to indicate what else the protagonist could have done. With the evaluation, a condition was complete and the next condition followed, starting again with the respective sharing scenario. Coding and data analysis The punishment/rewarding and evaluation were coded online by the experimenter for each session. Participants’ verbal protest/affirmation during the sharing scenarios was transcribed from videotape and coded from the transcriptions. Evaluation For children’s evaluation of each protagonist’s behavior on the 4-point smiley scale, a score from 1 (frowning smiley; very bad) to 4 (happy smiley; very good) was assigned. The justifications of the evaluations were categorized into three qualitatively different categories. The category action based comprised responses referring to the amount of items that the protagonist had shared/kept for herself (e.g., ‘‘I find it bad because [name of the puppet] has kept 5 stickers for herself and shared only 1 sticker”) or to the distribution of items that resulted from the protagonist’s sharing (e.g., ‘‘I find it bad because [name of the puppet] now has 5 gummy bears and [name of the recipient] has only 1 gummy bear”). Responses were classified into the category reciprocity based if they referred to the reciprocal aspect of the protagonist’s resource allocation (e.g., ‘‘I find it bad because [name of the recipient] has shared so much and [name of the puppet] has given her very little”). Responses that could not be clearly classified into one of these categories because, for example, they contained a (normative) judgment without any unambiguous reference to the item distribution or the aspect of reciprocity (e.g., ‘‘I find it bad because it’s unfair”), as well as inappropriate responses or no answer, were categorized as other responses/no answer. A random sample of 40% of all the sessions was chosen and recoded by a second independent person. For the evaluation justifications, Cohen’s kappa as a measure of Interrater reliability indicated nearly perfect agreement with a value of j = .84. Protest/affirmation Verbal protest/affirmation was coded during the phase when the protagonist puppet shared items with the initial allocator. First, participants’ utterances during the trials were transcribed. The onset of a trial was defined as the moment the experimenter handed out items to the protagonist. A trial was complete when the protagonist had distributed all items. Second, the utterances of each trial were, according to their valence, categorized into protest and affirmation. Both protest and affirmation could arise on different qualitative levels, so they were further classified into three distinct subcategories. The subcategory expectation-related comments (e) was used if participants stated that their expectations regarding the protagonist’s behavior were violated in the category of protest (e.g., ‘‘Really?”) or were met in the category of affirmation (e.g., ‘‘I knew it”). The subcategory imperative protest/affirmation (i) was used in the category of protest if participants tried to make the protagonist act differently (e.g., ‘‘No, you should give him something!”) and in the category of affirmation if participants reinforced the protagonist’s behavior (e.g., ‘‘Yes, you can do it like that!”). The subcategory normative protest/affirmation (n) was used if children commented on the protagonist’s behavior using normative vocabulary (e.g., ‘‘I find this very bad” in the category of protest, ‘‘Now it is fair” in the category of affirmation) or if children’s comments made evident some norm-related emotional reactions such as indignation. This coding scheme was based on the coding of protest behavior in previous work (e.g., Rakoczy et al., 2016; Wörle & Paulus, 2018). For the categorization of children’s verbal protest/affirma-

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tion during the different phases (see above), Cohen’s kappa indicated substantial agreement for protest, j = .78, and nearly perfect agreement for affirmation, j = .90. A protest (e/i/n) and affirmation (e/i/n) score was computed, indicating the number of trials (out of two) in which any form of protest/affirmation occurred, including expectation-related comments (e), imperative protest/affirmation (i), and normative protest/affirmation (n). Punishment/rewarding For the punishment/rewarding measure, the number of tasty and disgusting cookies (out of 3) that was given to the protagonist in each condition (match-high, match-low, or not matched) entered the analyses. Results Evaluation For the analysis of the measures that require a correct memory of the protagonists’ behaviors (evaluation and punishment/rewarding), two additional 3- and 4-year-old children were excluded from the final sample based on their incorrect answers to the check questions. This resulted in a subsample of 45 3- and 4-year-olds and 45 5- and 6-year-olds for these measures. Children’s ratings of the protagonist puppets’ behavior on the 4-point smiley scale were analyzed. Fig. 1 shows the mean evaluations that children of different age groups gave to the protagonists in the different conditions. A 3  2  2 mixed-model analysis of variance (ANOVA) with the within-participants factor Condition (matchhigh, match-low, or not matched) and the between-participants factors Age group (3- and 4-yearolds or 5- and 6-year-olds) and Gender (male or female) was conducted on children’s ratings. The analysis revealed a main effect of Condition, F(2, 170) = 31.24, p < .001, g2 = .27. Importantly, this effect was further qualified by a Condition  Age group interaction effect, F(2, 170) = 8.00, p < .001, g2 = .09. In addition, the overall ANOVA revealed a main effect of Gender on children’s ratings of the protagonists, F(1, 85) = 6.61, p = .012, g2 = .07. Across conditions and age groups, girls evaluated more positively (M = 2.79, SE = 0.12) than boys (M = 2.29, SE = 0.11). To follow up on the interaction between Condition and Age group, a repeated-measures ANOVA was conducted for each age group separately to test the effect of the factor Condition on children’s ratings. The analysis revealed a significant effect of Condition for 3- and 4-year-old children, F(2, 86) = 5.04, p = .009, g2 = .11, as well as for 5- and 6-year-old children, F(2, 88) = 40.57, p < .001, g2 = .48.

4

Evaluation (1-4)

3.5

3

2.5

2

1.5

1 Match-high

Match-low

Not matched

Condition 3-4-year-olds

5-6-year-olds

Fig. 1. Mean evaluations (1–4) as a function of Condition (match-high, match-low, or not matched) and Age group (3- and 4year-olds or 5- and 6-year-olds). Error bars indicate standard errors of the means.

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To further explore between which of the three conditions children of the different age groups differentiated in their evaluations, pairwise comparisons among all conditions were made for each age group using paired-samples t tests. For all follow-up tests that were conducted in the current study, Bonferroni correction was used to account for multiple comparisons. For 3- and 4-year-olds, the t tests revealed significant differences between the match-high condition and the match-low condition, t(43) = 3.01, p = .004, d = 0.49, as well as between the match-high condition and the not matched condition, t(43) = 2.64, p = .012, d = 0.51. However, the difference between the match-low condition and the not matched condition was not significant, t(44) = 0.10, p = .925, d = 0.02. For 5- and 6-year-olds, the t tests revealed significant differences among all three conditions. That is, 5- and 6-year-olds differentiated not only between the match-high condition and the match-low condition, t(44) = 5.30, p < .001, d = 1.04, and between the match-high condition and the not matched condition, t(44) = 9.19, p < .001, d = 1.96, but also between the match-low condition and the not matched condition, t(44) = 3.45, p = .001, d = 0.70. In sum, 3- and 4-year-olds evaluated the protagonist in the match-high condition more positively than the other two protagonists but did not differentiate between the match-low condition and the not matched condition. However, 5- and 6-year-olds also differentiated between the match-low condition and the not matched condition, evaluating the protagonist in the match-high condition most positively and the protagonist in the not matched condition most negatively. In addition to the comparisons between conditions, we conducted one-sample t tests for each age group to determine whether children not only distinguished between conditions but also actively evaluated the behavior of specific protagonists as positive or negative. To this end, children’s evaluations were tested against chance level, that is, a neutral evaluation. The results show that 3- and 4-year-olds’ evaluation significantly differed from chance only in the match-high condition, t(43) = 3.54, p = .001. Children of this age group actively rated the protagonist’s behavior in the match-high condition as positive. In contrast, their evaluations in the match-low condition, t(44) = 0.06, p = .954, and the not matched condition, t(44) = 0.17, p = .867, did not significantly differ from a neutral evaluation. The results show that 5- and 6-year-olds’ evaluations differed from chance in both the match-high condition, t(44) = 5.34, p < .001, and the not matched condition, t (44) = 8.25, p < .001. In the match-low condition, the difference failed to reach significance, t(44) = 1.83, p = .074. Notably, in the match-high condition children gave a positive evaluation, and in the not matched condition they gave a negative evaluation. In the match-low condition the tendency was also in the negative direction. Justifications Descriptive analyses were conducted for children’s evaluation justifications. For each condition (match-high, match-low, or not matched), data were first split into children who had evaluated the respective protagonist’s behavior positively (i.e., as good or very good on the smiley scale) and children who had evaluated the protagonist’s behavior negatively (i.e., as bad or very bad on the smiley scale), collapsed across age groups. Table 2 shows the number of children who provided answers from the different categories to justify their evaluations. The numbers show that action-based justifications were mostly used to justify a positive evaluation in the match-high condition and to justify a negative

Table 2 Evaluation justification: Children’s justifications of their evaluation in each condition subdivided according to the valence of their evaluation. Match-high

Action based Reciprocity based Other responses/no answer

Match-low

Not matched

Positive evaluation

Negative evaluation

Positive evaluation

Negative evaluation

Positive evaluation

Negative evaluation

26 (36.6) 13 (18.3) 32 (45.1)

9 (47.4) 1 (5.3) 9 (47.4)

7 (17.9) 9 (23.1) 23 (59.0)

28 (54.9) 1 (2.0) 22 (43.1)

4 (14.8) 1 (3.7) 22 (81.5)

34 (54.0) 7 (11.1) 22 (34.9)

Note. The table shows numbers (and percentages) of children who provided answers from the different categories.

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evaluation in the match-low and not matched conditions. In contrast, reciprocity-based justifications were most often used to justify a positive evaluation in the match-high condition and the match-low condition and to justify a negative evaluation in the not matched condition. In addition, descriptive analyses of children’s evaluation justifications were conducted for each age group separately, collapsing the data across conditions. Apart from no answer, action-based answers were most frequent in the group of 3- and 4-year-olds, being used 39 times (28.9%). Reciprocity-based answers were least frequent in this age group, being used only 4 times (3.0%). In between, there were other answers, being used 34 times (25.2%). No answer was given 58 times (43.0%) by 3- and 4-yearolds. In the group of 5- and 6-year-olds, action-based answers also represented the category that was used most often, namely 69 times (51.1%). Yet, the proportion of reciprocity-based answers was higher in that age group with 28 instances (20.7%). Other answers occurred 20 times (14.8%) among 5- and 6year-olds, and these children gave no answer 18 times (13.3%). Affirmation Fig. 2A shows the mean numbers of trials in which children showed some form of affirmation toward the protagonist in the match-high condition, the match-low condition, and the not matched condition. A 3  2 mixed-model ANOVA with the within-participants factor Condition (match-high, match-low, or not matched) and the between-participants factor Age group (3- and 4-year-olds or 5- and 6-year-olds) was computed on the mean number of trials in which children showed some form of affirmation (e/i/n). A preliminary analysis including the factor Gender (male or female) yielded no significant effect of this factor on children’s affirmation (e/i/n), so it was dropped from the main analysis. The ANOVA revealed a main effect of Condition, F(2, 178) = 7.61, p = .001, g2 = .08. Moreover, there was a Condition  Age group interaction effect, F(2, 178) = 3.28, p = .045, g2 = .04. To follow up on the interaction effect, we calculated for each age group separately whether children showed different amounts of affirmation (e/i/n) in the different conditions using a repeated-measures ANOVA. The analyses revealed a significant effect of the factor Condition for 3- and 4-year-olds, F(2, 90) = 5.54, p = .009, g2 = .11, as well as for 5- and 6-year-olds, F(2, 88) = 5.38, p = .006, g2 = .11. Pairwise comparisons revealed that 3- and 4-year-olds showed more affirmation in the match-high condition than in the not matched condition, t(46) = 2.48, p = .017, d = 0.41. Moreover, they showed more affirmation in the match-high condition than in the match-low condition, t(45) = 2.69, p = .010, d = 0.49. The difference between the not matched condition and the match-low condition was not significant, t(45) = 0.37, p = .710, d = 0.08. Pairwise comparisons revealed that 5- and 6-year-olds also showed significantly more affirmation in the match-high condition than in the not matched condition, t(44) = 2.85, p = .007. In addition, they showed more affirmation in the match-low condition than in the not matched condition, t(44) = 2.85, p = .007. However, there was no difference between the matchhigh condition and the match-low condition, t(44) = 0.00, p = 1.000, d = 0.00. Taken together, in line with their evaluations, 3- and 4-year-olds selectively showed more affirmation toward the protagonist in the match-high condition than toward the protagonists in the other two conditions. However, 5and 6-year-olds selectively affirmed both the protagonist in the match-high condition and the protagonist in the match-low condition but not the protagonist in the not matched condition. Protest Fig. 2B shows the mean numbers of trials in which children showed some form of protest in the match-high condition, the match-low condition, and the not matched condition. An ANOVA on the mean number of trials in which children showed some form of protest (e/i/n) was computed. A preliminary analysis including the factor Gender (male or female) yielded no significant effect of this factor on children’s protest (e/i/n), so it was dropped from the main analysis. Results revealed a main effect of Condition, F(2, 180) = 3.40, p = .039, g2 = .04. The Condition  Age group interaction effect did not reach significance, F(2, 180) = 0.79, p = .447, g2 = .01. To follow up on the significant main effect of Condition, we collapsed the data across age groups and further explored between which of the three conditions children differentiated in their protest (e/i/n). To this end, pairwise comparisons among all conditions were conducted using pairedsamples t tests. When correcting for multiple comparisons, results revealed no significant differences between the conditions [not matched condition–match-high condition, t(91) = 2.32, p = .023,

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A 0.7

Affirmation (0-2)

0.6 0.5 0.4 0.3 0.2 0.1 0 Match-high

Match-low

Not matched

Match-high

3-4-year-olds

Match-low

Not matched

5-6-year-olds

Condition by age group normative

imperative

expectation-related

B 0.7 0.6

Protest (0-2)

0.5 0.4 0.3 0.2 0.1 0 Match-high

Match-low

Not matched

Match-high

3-4-year-olds

Match-low

Not matched

5-6-year-olds

Condition by age group normative

imperative

expectation-related

Fig. 2. Protest/affirmation: Mean numbers of trials (0–2) in which participants showed some form of protest/affirmation as a function of Condition (match-high, match-low, or not matched) and Age group (3- and 4-year-olds or 5- and 6-year-olds). (A) Affirmation. (B) Protest. Error bars indicate standard errors of the means.

d = 0.31; not matched condition–match-low condition, t(91) = 0.89, p = .374, d = condition–match-low condition, t(91) = 1.75, p = .083, d = 0.25].

0.09; match-high

Punishment/rewarding Fig. 3 shows the descriptive results for the punishment/rewarding measure. Children’s distribution of tasty and disgusting cookies to the protagonists in the different conditions was analyzed. A 3  2  2 mixed-model ANOVA with the within-participants factors Condition (match-high, matchlow, or not matched) and Cookie type (tasty or disgusting cookies) and the between-participants factor Age group (3- and 4-year-olds or 5- and 6-year-olds) was computed on the number of given cook-

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Number of given cookies (out of 3)

3

2.5

2

1.5

1

0.5

0 Tasty cookies

Disgusting cookies

Match-high

Tasty cookies

Disgusting cookies

Match-low

Tasty cookies

Disgusting cookies

Not matched

Condition by cookie type 3-4-year-olds

5-6-year-olds

Fig. 3. Punishment/rewarding: Mean numbers of cookies (0–3) participants allocated to the protagonists as a function of Condition (match-high, match-low, or not matched), Age group (3- and 4-year-olds or 5- and 6-year-olds), and Cookie type (tasty or disgusting cookies). Error bars indicate standard errors of the means.

ies. A preliminary analysis including the factor Gender (male or female) yielded no significant effects of this factor, so it was dropped from the main analysis. The ANOVA revealed a significant main effect of Cookie type, F(1, 88) = 8.17, p = .005, g2 = .09, which was further qualified by a Cookie type  Condition interaction effect, F(2, 176) = 4.38, p = .014, g2 = .05, and a Cookie type  Age group interaction effect, F(1, 88) = 4.87, p = .030, g2 = .05. The Cookie type  Condition  Age group interaction effect was not significant, F(2, 176) = 0.13, p = .877, g2 = .00. To explore the Cookie type  Condition interaction effect, we performed post hoc t tests (across the factor age group) for all three conditions separately, comparing whether there was a difference in the number of tasty and disgusting cookies given to the protagonists in the different conditions. Results revealed that children gave more tasty cookies than disgusting cookies in the match-high condition, t(89) = 4.23, p < .001, d = 0.65. For the match-low condition and the not matched condition, the number of given tasty cookies was not significantly different from the number of given disgusting cookies. To follow up on the Cookie type  Age group interaction effect, we performed post hoc t tests (across the factor condition) for both age groups separately, comparing whether 3- and 4-year-olds and 5- and 6-year-olds gave a different number of tasty and disgusting cookies across conditions. Results revealed that, overall, 3- and 4-year-olds gave more tasty cookies than disgusting cookies, t (44) = 3.78, p < .001, d = 0.74. This difference was not significant for 5- and 6-year-olds, who gave as many tasty cookies as disgusting cookies.

Discussion The current study aimed at investigating whether reciprocity represents a norm for humans and whether such a norm develops during the preschool period. Given that a core element of normativity is to appreciate the agent-neutral validity of norms, we explored how children would react if they observed norm violations and norm compliance from a third-party perspective (i.e., when self-interest is unlikely to play a role). We investigated 3- to 6-year-old children’s normative understanding of reciprocity in a sharing context. Thereby, they were presented with three scenarios

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in which they could observe an agent either reciprocating the sharing of a high proportion of resources, reciprocating the sharing of a small proportion of resources, or not reciprocating at all, giving only a small proportion of resources to someone who had previously benefitted her. The results showed that, in line with our hypotheses, children of all age groups appreciated it when a high proportion of resources was shared, but only children among the group of 5- and 6-year-olds also considered reciprocity as normatively relevant. On a group level, a normative understanding of reciprocity is clearly reflected in 5- and 6-year-olds’ verbal evaluations and reasoning. Moreover, some of the 5- and 6-year-olds actively enforced reciprocal behavior through affirmation. Yet, violations against the reciprocity norm seem to be not so severe for children at that age that they are willing to protest against defectors or to punish them by allocating negatively valued resources. Overall, the findings provide some support for the theoretical notion of a reciprocity norm in humans (Gouldner, 1960). Moreover, the developmental effect speaks for a ‘‘reciprocity is secondary” model, according to which an initial appreciation of prosociality gets shaped by normative concerns for reciprocity during the course of development. At the end of the preschool years, a norm for prosociality and a reciprocity norm seem to coexist. The current study contributes to a recent line of research that explores the early foundations of normativity. It demonstrates that young children not only have norms regarding antisocial behavior such as harm (Vaish et al., 2011) but also think of fairness principles in normative terms and actively enforce fairness norms, in this case a reciprocity norm, in others. Thereby, the current study complements evidence of an equality norm (Cooley & Killen, 2015; Rakoczy et al., 2016) and a charity norm (Wörle & Paulus, 2018) in preschoolers. Regarding the principle of reciprocity, we found that children’s understanding develops earlier than classical theories (Piaget, 1932) and empirical research (Berndt, 1977, 1979; Damon, 1977) have suggested. Our study adds to more recent research showing that already infants implicitly evaluate certain types of reciprocity as positive (e.g., Meristo & Surian, 2013), that 3-year-olds have descriptive expectations that others would reciprocate (e.g., Olson & Spelke, 2008), and that 3-year-olds show contingent reciprocal behavior (e.g., Warneken & Tomasello, 2013) by demonstrating that at 5 or 6 years of age children endorse a norm of reciprocity. In our study, 5- and 6-year-olds demonstrated an appreciation of a reciprocity norm next to an appreciation of prosociality. This was evident in their normative judgments and reasoning. Moreover, they relied on spontaneous verbal affirmation to actively promote norm compliance in others. The fact that they did so spontaneously in a third-party scenario indicates that they have already internalized the reciprocity norm and apply it in an agent-neutral manner. We focus on both measures in the following paragraphs. The developmental trend toward a normative understanding of reciprocity is most evident in children’s evaluations. Children of all age groups evaluated the agent who reciprocated sharing a high proportion of resources most positively, suggesting that prosociality plays an important role in preschoolers’ normative views. Yet, most important, 5- and 6-year-olds, but not 3- and 4-year-olds, also differentiated between the agent who reciprocated sharing a small proportion of resources and the agent who did not reciprocate at all, evaluating the latter even more negatively. Given that these two agents did not differ in the total (small) amount of resources that they shared but differed only in terms of reciprocity, this finding can be interpreted as evidence for 5- and 6-year-olds’ normative conceptualization of reciprocity. Not only did 5- and 6-year-olds differentiate between all agents, but comparisons against a neutral evaluation also revealed that they actively evaluated the agent who reciprocated sharing a high proportion of resources positively and evaluated the agent who did not reciprocate negatively. Their evaluation of the agent who reciprocated sharing a small proportion of resources showed a negative yet not significant tendency in the negative direction. This also shows that 5- and 6-year-olds understand reciprocity in normative terms and that a reciprocity norm seems to coexist with an appreciation of prosociality. Moreover, children’s evaluations speak for a simultaneous consideration of prosociality and reciprocity in 5- and 6-year-olds, whereas 3- and 4-year-olds seem to disregard reciprocity in their explicit evaluations by exclusively focusing on the proportion that was shared. These conclusions are underpinned by children’s justifications of their evaluations; whereas 3- and 4-year-olds almost exclusively relied on justifications that referred to the proportion of shared resources, 5- and 6-year-olds also, yet not exclusively, used justifications that referred to reciprocity. This suggests that older preschoolers consider the proportion of shared

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resources, and thus prosociality, as well as reciprocity. Importantly, they specifically used reciprocitybased justifications for positive evaluations of the agents who acted reciprocally and for a negative evaluation of the agent who did not act reciprocally. Taken together, these findings suggest that reciprocity plays an important role in older preschoolers’ explicit normative judgments and reasoning and that it complements an appreciation of general prosociality. In line with their evaluations, 5- and 6-year-old preschoolers spontaneously enforced compliance with a reciprocity norm through affirmation, both when sharing a high proportion of resources was reciprocated and when sharing a small proportion of resources was reciprocated. However, 3- and 4-year-olds did not selectively enforce any agent. These findings further support the conclusion that 5- and 6-year-olds consider reciprocity to be a norm. In contrast to the findings on affirmation, no selective enforcement of a reciprocity norm through protest could be found. On a mere descriptive level, however, the pattern of children’s protest matches the pattern that we found for their evaluations and affirmation. Whereas 3- and 4-year-olds were more likely to protest against the agents who shared only a small proportion of resources (irrespective of reciprocity), 5- and 6-year-olds tended to selectively protest against the agent who did not share reciprocally. In sum, older preschoolers enforced a reciprocity norm, in addition to prosociality, through affirmation, whereas younger children did not enforce any norm. These findings are in line with children’s evaluations, speaking for the development of a reciprocity norm in older preschoolers that is preferably enforced through affirmation (rather than protest). The development toward a normative understanding of reciprocity, as evident in the other measures, is not reflected in children’s punishment and reward behavior. Besides a general inclination to allocate more tasty cookies than disgusting cookies that was found only in 3- and 4-year-olds, children across age groups allocated more tasty cookies than disgusting cookies to the agent who reciprocated sharing a high proportion of resources but allocated the same amount of both cookie types to the other two agents. Thus, across age groups, children seem to selectively reward sharing a high proportion of resources but not reciprocity. In contrast to the other measures of normativity, no consideration of reciprocity could be found in 5- and 6-year-olds’ punishment and reward behavior. There are different possible interpretations of these results. One could argue that they speak against a norm for reciprocity in preschoolers. Yet, this interpretation seems unlikely given the corroborative findings from the other measures. An alternative explanation of these findings is that children do not consider violations of a reciprocity norm as so severe that they deserve punishment. One might speculate why this is the case. On the one hand, it could be that the consequences of norm violations—concern for victims has been suggested to play a role in third-party punishment (Riedl, Jensen, Call, & Tomasello, 2015)—are less obvious in the context of fairness norm violations. Along these lines, our findings converge with previous work, showing that children younger than 6 years do not readily punish fairness norm violations (McAuliffe et al., 2015; Salali et al., 2015) even though they punish norm violations inflicting antisocial behavior (Kenward & Dahl, 2011; Kenward & Östh, 2012, 2015; Vaish et al., 2010). On the other hand, it is possible that the allocation of sweets, even though successfully applied in previous work (e.g., Wörle & Paulus, 2018), does not represent a sensitive measure of punishment and rewarding. In future work, alternative measures should be considered such as asking children whether an agent should get in trouble for what the agent did (cf. Killen et al., 2011). A third possibility is that children think of reciprocity as a value rather than a duty. Whereas duties refer to obligations with deontic force, values refer to what is desirable in the sense of virtues (cf. Heyd, 2016). Thus, values are supererogatory, which means that they go beyond one’s obligation. The absence of protest against violations of a reciprocity norm would be in line with this interpretation. Taken together, we interpret the findings as evidence for the development of a reciprocity norm in preschoolers. The developmental pattern suggests that on a normative level there is an initial appreciation of prosociality that gradually gets shaped by a concern for reciprocity. At first, our findings seem surprising in the light of previous research that demonstrates sensitivity to the principle of reciprocity even in infants (e.g., Meristo & Surian, 2013). Yet, as outlined, such implicit understanding does not equal a normative stance as it was conceptualized in the current study. Some key features of norms, such as their binding force and their application in an agent-neutral manner, are not addressed by the preference measures used in preverbal infants (cf. Dahl, 2014). In the current study, we directly addressed these features. From our findings, we conclude that a reciprocity norm develops during the

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preschool years and is clearly present in older preschoolers. It critically affected 5- and 6-year-olds’ explicit normative judgments and reasoning as well as their spontaneous norm enforcement toward third parties in the form of affirmation. These findings are informative with respect to the existence of a reciprocity norm in humans and its early ontogeny. Yet, the current study also has some limitations and leaves us with open research questions. We will highlight five of them in the following paragraphs. First, future studies are needed to explore which factors contribute to the development of a reciprocity norm. For example, it is possible that the ability to take into account different aspects of a situation (decentration; cf. Piaget, 1932) plays a role in the developmental changes that were found. Only older preschoolers were able to simultaneously consider the total amount that was shared and the history of sharing that preceded the actual decision. However, it should be noted that normative development cannot be reduced to advances in more general cognitive abilities. Although decentration might indeed have enabled children to consider all relevant aspects, it does not explain why children conceive of reciprocity as being normatively required instead of considering it as unimportant. Thus, the development of a reciprocity norm rests on both cognitive and motivational processes, and it is up to future studies to uncover the factors that add to its development. Second, given the diverging findings of reciprocity on an implicit evaluative level, a behavioral level, and a normative level, future research is needed to investigate how these different levels relate to each other. Especially the differences between the current study and infant studies (e.g., Hamlin et al., 2011) require more in-depth investigation. More specifically, it should be examined whether or not children’s abilities form a developmental sequence and which factors drive the development on each level. Another important aspect is the behavioral significance of a reciprocity norm in children. There is a longstanding debate on whether people comply with their normative views (e.g., Blasi, 1983; Killen & Dahl, 2018; Turiel, 2003; Walker, 2004). For young children, the situation is least clear. On the one hand, there is evidence that even preschoolers align their behavior with the norms they endorse (Abramson, Daniel, & Knafo-Noam, 2018; Paulus, Nöth, & Wörle, 2018). On the other hand, studies found that the behavioral level and normative level become integrated only after the preschool years (e.g., Smith, Blake, & Harris, 2013). Kogut (2012) demonstrated that norm compliance in preschoolers still depends on potential sanctions. The absence of selective protest and punishment in the current study might suggest that preschoolers do not yet fully grasp the severity of reciprocity norm violations. Thus, it might be that they themselves would not comply with a reciprocity norm either. It is up to future studies to further examine this possibility. Third, the current study shows us that reciprocity seems to develop through at least 5 years, but it does not tell us anything about the further development of a reciprocity norm. Because reciprocal behavior changes until early adolescence (House, 2017), a reciprocity norm might also develop beyond toddlerhood. In the current study, evidence for a reciprocity norm was not found in children’s protest and punishment behavior but was found only in their evaluations and affirmation. Future studies could investigate whether a normative understanding of reciprocity develops beyond the age of 5 or 6 years, with an inclination to punish and protest against norm violations. Thus, from considering reciprocity as supererogatory, children might come to think of reciprocity as a duty with a high degree of obligation. Alternatively, the classification of reciprocity as either a supererogatory value or a duty might depend on the context rather than on developmental factors. For example, it might vary as a function of the specific act that is to be reciprocated. In addition, given ample work on crosscultural variation in the development of prosocial and strategic behavior (e.g., Blake et al., 2015), cross-cultural examinations on the development of children’s normative views on reciprocity would be valuable. Particularly given strong claims that reciprocity might be a universal norm (Gouldner, 1960), empirical research is necessary to critically examine whether or not this norm already affects young children from different cultures. Fourth, an open question concerns the generalizability of our findings. The current study was conducted in a laboratory, and children observed puppets as agents. Future research should investigate whether our findings generalize to children’s behavior in their natural environments, namely to their everyday interactions with peers and/or adults. Moreover, we investigated children’s normative understanding of reciprocity in a sharing situation as one important yet specific context. Future studies could investigate how broad children’s normative understanding of reciprocity is and whether it

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generalizes to other types of prosocial behavior (e.g., helping, comforting) or even to antisocial behavior (e.g., stealing). Adults indeed show a strong behavioral tendency toward negative reciprocity in the form of antisocial behavior (Gray, Ward, & Norton, 2014; Keysar, Converse, Wang, & Epley, 2008). Children were found to act similarly, and they even indicate this to be the way one should act (Chernyak, Leimgruber, Dunham, Hu, & Blake, 2019). Thus, repaying antisocial acts (i.e., punishment) might be a normative obligation because it is crucial for establishing norm compliance and, therefore, social stability. A final point concerns the question of how different fairness norms relate to each other and how they are weighed when in conflict. The current research design was optimized to examine the emergence of a reciprocity norm. A limitation is that it is not suitable to measure the relative strength of a reciprocity norm in contrast to other norms. The current data suggest that prosociality might also represent a norm in preschoolers. Indeed, a ‘‘norm of giving” (Leeds, 1963) that complements a norm of reciprocity in certain situations has been theoretically described. Our findings are in line with this assumption, suggesting a simultaneous consideration of prosociality and reciprocity in older preschoolers. This was most evident in the condition where an agent reciprocated but in doing so shared only a small amount of resources. Yet, to determine the relative strength of children’s normative concern for reciprocity, a context in which prosociality and reciprocity are in conflict would be interesting. Such a study could present children with an agent who shares a high proportion of resources but thereby violates a reciprocity norm. If children still enforced reciprocal behavior in this situation, it would indicate that they appreciate reciprocity more than prosociality. Yet, based on the evidence that preschool children highly appreciate generous and altruistic others (e.g., Kenward & Dahl, 2011; Van de Vondervoort et al., 2018), it is unlikely that they prioritize reciprocity over generosity. In sum, while providing first evidence for the presence of a reciprocity norm in preschoolers, the current data do not reveal the strength of a reciprocity norm at that age. It seems that the normative concern for reciprocity is rather weak when it first emerges given that children did not protest against or punish reciprocity norm violations. It is up to future studies to determine whether or not it gets stronger as children get older. In sum, the current study provides evidence for significant developmental changes in children’s normative understanding of reciprocity during the preschool period. Although a reciprocity norm does not seem to play a role for younger preschool children, older preschool children clearly endorse it. By demonstrating an early normative conceptualization of reciprocity, we provide evidence for an influential theory suggesting reciprocity to be a universal normative principle in humans. Acknowledgments For help with data acquisition and coding, we are thankful to Christina Seidel and Sarah Schober. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. References Abramson, L., Daniel, E., & Knafo-Noam, A. (2018). The role of personal values in children’s costly sharing and non-costly giving. Journal of Experimental Child Psychology, 165, 117–134. Axelrod, R., & Hamilton, W. D. (1981). The evolution of cooperation. Science, 211, 1390–1396. Baumard, N., André, J. B., & Sperber, D. (2013). A mutualistic approach to morality: The evolution of fairness by partner choice. Behavioral and Brain Sciences, 36, 59–78. Berndt, T. J. (1977). The effect of reciprocity norms on moral judgment and causal attribution. Child Development, 48, 1322–1330. Berndt, T. J. (1979). Lack of acceptance of reciprocity norms in preschool children. Developmental Psychology, 15, 662–663. Blake, P. R., McAuliffe, K., Corbit, J., Callaghan, T. C., Barry, O., Bowie, A., ... Wrangham, R. (2015). The ontogeny of fairness in seven societies. Nature, 528, 258–261. Blasi, A. (1983). Bridging moral cognition and moral action: A theoretical perspective. Developmental Review, 3, 178–210. Brownell, C. A. (2013). Early development of prosocial behavior: Current perspectives. Infancy, 18, 1–9. Bull, J. J., & Rice, W. R. (1991). Distinguishing mechanisms for the evolution of cooperation. Journal of Theoretical Biology, 149, 63–74. Burger, J. M., Sanchez, J., Imberi, J. E., & Grande, L. R. (2009). The norm of reciprocity as an internalized social norm: Returning favors even when no one finds out. Social Influence, 4, 11–17.

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Burns, M. P., & Sommerville, J. (2014). ‘‘I pick you”: The impact of fairness and race on infants’ selection of social partners. Frontiers in Psychology, 5. https://doi.org/10.3389/fpsyg.2014.00093. Chernyak, N., Leimgruber, K., Dunham, Y., Hu, J., & Blake, P. (2019). Paying back those who harmed us but not those who helped us: Direct negative reciprocity precedes direct positive reciprocity in early development. Psychological Science. https://doi. org/10.31234/osf.io/vjb6q. Advance online publication. Cooley, S., & Killen, M. (2015). Children’s evaluations of resource allocation in the context of group norms. Developmental Psychology, 51, 554–563. Dahl, A. (2014). Definitions and developmental processes in research on infant morality. Human Development, 57, 241–249. Dahl, A., Schuck, R. K., & Campos, J. J. (2013). Do young toddlers act on their social preferences?. Developmental Psychology, 49, 1964–1970. Damon, W. (1977). The social world of the child. San Francisco: Jossey-Bass. Fehr, E., & Fischbacher, U. (2004). Third-party punishment and social norms. Evolution and Human Behavior, 25, 63–87. Fehr, E., Fischbacher, U., & Gächter, S. (2002). Strong reciprocity, human cooperation, and the enforcement of social norms. Human Nature, 13, 1–25. Gallucci, M., & Perugini, M. (2000). An experimental test of a game-theoretical model of reciprocity. Journal of Behavioral Decision Making, 13, 367–389. Gouldner, A. W. (1960). The norm of reciprocity: A preliminary statement. American Sociological Review, 25, 161–178. Gray, K., Ward, A. F., & Norton, M. I. (2014). Paying it forward: Generalized reciprocity and the limits of generosity. Journal of Experimental Psychology: General, 143, 247–254. Gurven, M. (2006). The evolution of contingent cooperation. Current Anthropology, 47, 185–192. Hamlin, J. K., Wynn, K., Bloom, P., & Mahajan, N. (2011). How infants and toddlers react to antisocial others. Proceedings of the National Academy of Sciences of the United States of America, 108, 19931–19936. Heyd, D. (2016). Supererogation. In N. Zalta (Ed.), The Stanford encyclopedia of philosophy (Spring 2016 ed.). Retrieved from https://plato.stanford.edu/archives/spr2016/entries/supererogation/. House, B. R. (2017). Diverse ontogenies of reciprocal and prosocial behavior: Cooperative development in Fiji and the United States. Developmental Science, 20, e12466. Jensen, K. (2010). Punishment and spite, the dark side of cooperation. Philosophical Transactions of the Royal Society B: Biological Sciences, 365, 2635–2650. Josephs, M., Kushnir, T., Gräfenhain, M., & Rakoczy, H. (2016). Children protest moral and conventional violations more when they believe actions are freely chosen. Journal of Experimental Child Psychology, 141, 247–255. Kanngiesser, P., & Warneken, F. (2012). Young children consider merit when sharing resources with others. PLoS One, 7(8), e43979. Karniol, R. (1978). Children’s use of intention cues in evaluating behavior. Psychological Bulletin, 85, 76–85. Kenward, B., & Dahl, M. (2011). Preschoolers distribute scarce resources according to the moral valence of recipients’ previous actions. Developmental Psychology, 47, 1054–1064. Kenward, B., Hellmer, K., Winter, L. S., & Eriksson, M. (2015). Four-year-olds’ strategic allocation of resources: Attempts to elicit reciprocation correlate negatively with spontaneous helping. Cognition, 136, 1–8. Kenward, B., & Östh, T. (2012). Enactment of third-party punishment by 4-year-olds. Frontiers in Psychology, 3. https://doi.org/ 10.3389/fpsyg.2012.00373. Kenward, B., & Östh, T. (2015). Five-year-olds punish antisocial adults. Aggressive Behavior, 41, 413–420. Keysar, B., Converse, B. A., Wang, J., & Epley, N. (2008). Reciprocity is not give and take: Asymmetric reciprocity to positive and negative acts. Psychological Science, 19, 1280–1286. Killen, M., & Dahl, A. (2018). Moral judgment: Reflective, interactive, spontaneous, challenging, and always evolving. In K. Gray & J. Graham (Eds.), Atlas of moral psychology (pp. 20–30). New York: Guilford. Killen, M., Mulvey, K. L., Richardson, C., Jampol, N., & Woodward, A. (2011). The accidental transgressor: Morally-relevant theory of mind. Cognition, 119, 197–215. Killen, M., & Smetana, J. G. (2015). Origins and development of morality. In M. E. Lamb (Ed.), Handbook of child psychology and developmental science (Vol. 3, 7th ed., pp. 701–749). New York: Wiley–Blackwell. Kogut, T. (2012). Knowing what I should, doing what I want: From selfishness to inequity aversion in young children’s sharing behavior. Journal of Economic Psychology, 33, 226–236. Kuhlmeier, V. A., Dunfield, K. A., & O’Neill, A. C. (2014). Selectivity in early prosocial behavior. Frontiers in Psychology, 5. https:// doi.org/10.3389/fpsyg.2014.00836. Leeds, R. (1963). Altruism and the norm of giving. Merrill-Palmer Quarterly of Behavior and Development, 9, 229–240. Leman, P. J., & Björnberg, M. (2010). Conversation, development, and gender: A study of changes in children’s concepts of punishment. Child Development, 81, 958–971. Levitt, M. J., Weber, R. A., Clark, M. C., & McDonnell, P. (1985). Reciprocity of exchange in toddler sharing behavior. Developmental Psychology, 21, 122–123. Li, V., Spitzer, B., & Olson, K. R. (2014). Preschoolers reduce inequality while favoring individuals with more. Child Development, 85, 1123–1133. Marsh, H. W., Ellis, L. A., & Craven, R. G. (2002). How do preschool children feel about themselves? Unraveling measurement and multidimensional self-concept structure. Developmental Psychology, 38, 376–393. Martin, A., & Olson, K. R. (2015). Beyond good and evil: What motivations underlie children’s prosocial behavior? Perspectives on Psychological Science, 10, 159–175. McAuliffe, K., Jordan, J. J., & Warneken, F. (2015). Costly third-party punishment in young children. Cognition, 134, 1–10. Mead, G. H. (1934). Mind, self, and society. Chicago: University of Chicago Press. Meristo, M., & Surian, L. (2013). Do infants detect indirect reciprocity? Cognition, 129, 102–113. Olson, K. R., & Spelke, E. S. (2008). Foundations of cooperation in young children. Cognition, 108, 222–231. Paulus, M. (2014a). The early origins of human charity: Developmental changes in preschoolers’ sharing with poor and wealthy individuals. Frontiers in Psychology, 5. https://doi.org/10.3389/fpsyg.2014.00344.

M. Wörle, M. Paulus / Journal of Experimental Child Psychology 188 (2019) 104693

19

Paulus, M. (2014b). The emergence of prosocial behavior: Why do infants and toddlers help, comfort, and share?. Child Development Perspectives, 8, 77–81. Paulus, M. (2016). It’s payback time: Preschoolers selectively request resources from someone they had benefitted. Developmental Psychology, 52, 1299–1306. Paulus, M., Nöth, A., & Wörle, M. (2018). Preschoolers’ resource allocations align with their normative judgments. Journal of Experimental Child Psychology, 175, 117–126. Piaget, J. (1932). The moral judgment of the child. New York: Free Press. Rakoczy, H., Kaufmann, M., & Lohse, K. (2016). Young children understand the normative force of standards of equal resource distribution. Journal of Experimental Child Psychology, 150, 396–403. Rakoczy, H., & Schmidt, M. F. H. (2013). The early ontogeny of social norms. Child Development Perspectives, 7, 17–21. Rakoczy, H., Warneken, F., & Tomasello, M. (2008). The sources of normativity: Young children’s awareness of the normative structure of games. Developmental Psychology, 44, 875–881. Riedl, K., Jensen, K., Call, J., & Tomasello, M. (2015). Restorative justice in children. Current Biology, 25, 1731–1735. Robbins, E., & Rochat, P. (2011). Emerging signs of strong reciprocity in human ontogeny. Frontiers in Psychology, 2. https://doi. org/10.3389/fpsyg.2011.00353. Salali, G. D., Juda, M., & Henrich, J. (2015). Transmission and development of costly punishment in children. Evolution and Human Behavior, 36, 86–94. Sebastián-Enesco, C., Hernández-Lloreda, M. V., & Colmenares, F. (2013). Two and a half-year-old children are prosocial even when their partners are not. Journal of Experimental Child Psychology, 116, 186–198. Sebastián-Enesco, C., & Warneken, F. (2015). The shadow of the future: 5-Year-olds, but not 3-year-olds, adjust their sharing in anticipation of reciprocation. Journal of Experimental Child Psychology, 129, 40–54. Shumaker, S. A., & Jackson, J. S. (1979). The aversive effects of nonreciprocated benefits. Social Psychology Quarterly, 42, 148–158. Smith, C. E., Blake, P. R., & Harris, P. L. (2013). I should but I won’t: Why young children endorse norms of fair sharing but do not follow them. PLoS One, 8(3), e59510. Trivers, R. L. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46, 35–57. Turiel, E. (2003). Morals, motives, and actions. In L. Smith, C. Rogers, & P. Tomlinson (Eds.), Development and motivation: Joint perspectives (Monograph Series II, Serial No. 2, pp. 29–40). Leicester, UK: British Psychological Society. Vaish, A., Carpenter, M., & Tomasello, M. (2010). Young children selectively avoid helping people with harmful intentions. Child Development, 81, 1661–1669. Vaish, A., Missana, M., & Tomasello, M. (2011). Three-year-old children intervene in third-party moral transgressions. British Journal of Developmental Psychology, 29, 124–130. Van de Vondervoort, J. W., Aknin, L. B., Kushnir, T., Slevinsky, J., & Hamlin, J. K. (2018). Selectivity in toddlers’ behavioral and emotional reactions to prosocial and antisocial others. Developmental Psychology, 54, 1–14. Walker, L. J. (2004). Gus in the gap: Bridging the judgment–action gap in moral functioning. In D. K. Lapsley & D. Narvaez (Eds.), Moral development, self, and identity (pp. 1–20). Mahwah, NJ: Lawrence Erlbaum. Warneken, F., & Tomasello, M. (2013). The emergence of contingent reciprocity in young children. Journal of Experimental Child Psychology, 116, 338–350. Whatley, M. A., Webster, J. M., Smith, R. H., & Rhodes, A. (1999). The effect of a favor on public and private compliance: How internalized is the norm of reciprocity?. Basic and Applied Social Psychology, 21, 251–259. Wörle, M., & Paulus, M. (2018). Normative expectations about fairness: The development of a charity norm in preschoolers. Journal of Experimental Child Psychology, 165, 66–84.