Short-term direct reciprocity of prosocial behaviors in Japanese preschool children.

Direct reciprocity plays an essential role in forming cooperative relationships. Direct reciprocity requires individuals to keep track of past interactions and condition their behavior on the previous behavior of their partners. In controlled experimental situations, it is known that children establish direct reciprocity according to the partner's behavior, but this has not been verified in real life. This study aims to identify the establishment of short-term direct reciprocity in response to peers' behaviors among Japanese preschoolers aged 5 and 6. It employs naturalistic observation at a nursery school. In addition, the psychological process for direct reciprocity was examined. The findings demonstrated that after receiving prosocial behavior, the recipient child returned the prosocial behavior more frequently within 7 minutes, compared with control situations; this suggests that 5-to 6-year-olds formed direct reciprocity in the short term when interacting with their peers. Additionally, recipient children tended to display affiliative behavior after receiving prosocial behavior. Positive emotions toward initiating children may have been caused by receiving prosocial behavior, and this psychological change modified short-term direct reciprocity.

Preschool children's behavioral tendency toward social indirect reciprocity.

Social indirect reciprocity seems to be crucial in enabling large-scale cooperative networks among genetically unrelated individuals in humans. However, there are relatively few studies on social indirect reciprocity in children compared to adults. Investigating whether young children have a behavioral tendency toward social indirect reciprocity will help us understand how and when the fundamental ability to form cooperative relationships among adults is acquired. Using naturalistic observation at a nursery school, this study examined whether 5- to 6-year-olds show a behavioral tendency to engage in social indirect reciprocity in response to their peers' prosocial behavior toward a third party. The results revealed that bystander children tended to display prosocial behavior toward their peers more frequently after observing these peers' prosocial behavior toward third-party peers, compared with control situations; this suggests that 5- to 6-year-olds may have an essential behavioral tendency to establish social indirect reciprocity when interacting with peers in their daily lives. In addition, bystanders tended to display affiliative behavior after observing focal children's prosocial behavior. In other words, observing peers' prosocial behavior toward third-party peers evoked bystanders' positive emotions toward the helpers. Considering both the present results and previous findings, we speculate that in preschoolers, such positive emotions might mediate the increase in the bystander's prosocial behavior toward the helper. In addition, an intuitional emotional process plays an important role in the preschooler's behavioral tendency toward social indirect reciprocity in natural interactions with peers.

Gaze following among toddlers.

Children's cooperative activities with their peers become markedly coordinated during the 3rd year of life. During these activities, the child needs to follow his/her peers' gaze to objects, and look at the same objects to initiate coordinated action. Since 3-year-olds' ability to follow their peers' gaze has not been studied, we experimentally investigated this in our study. In the experimental trials, an experimenter induced a child (looker) to look at a doll on display, and observed the reaction of another child (follower) who was in front of the looker (and not looking at the doll). In the control trials, the experimenter displayed the doll in an identical manner when the follower was alone. The followers followed the gaze of the lookers, looking at the doll in approximately 90% of the experimental trials, compared with 20% of the control trials. These results indicate that 3-year-olds can follow their peers' gaze.

Do pointing gestures by infants provoke comments from adults?

In the field of developmental psychology, there is speculation that pointing gestures by infants are good precursors of infant language acquisition, and some researchers have found correlations between these pointing gestures and some indices of language acquisition. Infants' pointing gestures are presumably related to language acquisition because they provoke verbal responses from adults. To test this, seven boys and six girls were observed during free play time in a nursery classroom, and post-pointing and matched-control data were collected. Comparison between these data confirmed that the nursery staff spoke to infants at a significantly earlier stage in post-pointing sequences, compared with control sequences, indicating that pointing gestures elicit verbal responses from adult caregivers.

Development of eating behavior by Japanese toddlers in a nursery school: relation to independent walking.

The eating behavior of 32 toddlers in a nursery school at 10, 12, and 14 months old was observed in relation to the age at onset of independent walking. With increasing age, the frequency at which the toddlers ate food given by a teacher decreased, and the frequency at which the toddlers ate by themselves increased. The toddlers who started walking earlier also advanced faster in the development of eating behavior. The time when the frequency of eating by oneself surpassed the frequency of passive eating coincided with the time when the toddlers started walking.

[Indoor and outdoor peer relations in preschool children].

This study examined whether the choice of interactors is influenced by indoor and outdoor situations. Peer relations among twenty three-year-old, eighteen four-year-old, and twenty five-year-old children in an urban preschool in Japan were observed during indoor and outdoor free play situations. We analyzed the partners in the interactions, the number, and the stability of interactors. The Shannon-Wiener diversity index (H) was used to measure the stability of interactors. In outdoor situations, three-year-old and four-year-old children were involved with a diversity of interactors, while four-year-old children's preferred friends were stable. Five-year-old children showed a relation with stable interactors in both indoor and outdoor situations, choosing different interactors in each situation. In addition, the children who had few interactors in indoor situations increased their relations with interactors in outdoor situations. These results suggest that three-year-old and four-year-old children are affected by environmental factors that seem to stimulate the children's physiognomic perception, whereas five-year-old children make use of the environment. Opportunities for children to encounter various situations and meet various peers may facilitate the development of social relations.

Grooming relationships of adolescent orphans in a free-ranging group of Japanese macaques (Macaca fuscata) at Katsuyama: a comparison among orphans with sisters, orphans without sisters, and females with a surviving mother.

The present study examined grooming relationships of adolescent females in a free-ranging group of Japanese macaques (Macaca fuscata) at Katsuyama. To assess whether the loss of the mother influenced the grooming relationships of adolescent females (5-7 years old), we compared the time spent in grooming interactions and the number of grooming partners among the following three groups: 6 adolescent orphans with sisters, 9 adolescent orphans without sisters, and 11 adolescent non-orphans with surviving mothers. In Japanese macaques, grooming most frequently occurs between mothers and their daughters. Therefore, it is expected that if the mother is lost, orphans will devote less time to grooming interactions than non-orphans. However, the time spent in overall grooming interactions did not differ among the three groups. While non-orphans maintained grooming relationships with their mothers, orphans acquired alternative grooming relationships with other group members. Orphans adopted two kinds of tactics to compensate for the loss of the mother. First, adolescent orphans with sisters developed more affiliative grooming relationships with their sisters than non-orphans with sisters. Secondly, adolescent orphans without sisters spent more time in grooming interactions with same-aged females and non-related adult females. Moreover, regarding grooming interactions with same-aged females and non-related adult females, orphans without sisters had a larger number of grooming partners than non-orphans. These results indicate that adolescent females have enough flexibility to develop their grooming network after the loss of their mothers, and that the lack of mother and sisters might accelerate socialization of adolescent females and enable them to be integrated in reciprocal adult grooming relationships.