Children's affiliation toward peers reflected in their picture drawings.

Previous studies have demonstrated that a picture-drawing task can be an indicator of the affiliation children have with their peers. When a child draws himself/herself along with a peer, the distance between them is assumed to represent the extent of the affiliation held by the child toward the peer: the shorter the distance is, the more affiliation the child has. However, some issues remain before the picture-drawing task is established as a way to measure children's affiliation, including the possibility that the instructions might bias the children's responses (Thomas & Gray, 1992), and inconsistency over where to measure in the children's drawings (e.g., Song et al., 2015). In this study, we focused on the above two issues and addressed whether the picture-drawing task can be used for measuring children's affiliation toward peers. We conducted our study in Japanese nursery schools with 3- to 6-year-old children (N = 676), who drew pictures of themselves and a classmate. Teachers rated how much the children had played with the drawn peer. We found that the more a child had an affiliative relationship with a peer, the shorter the distance between the drawn child and peer was when measuring the closest points and the center between the two drawn figures. Our research sheds light on the validity of the picture-drawing task for measuring children's affiliation.

Possible mechanism for improving the endogenous immune system through the blockade of peripheral µ-opioid receptors by treatment with naldemedine.

BACKGROUND: It has been considered that activation of peripheral µ-opioid receptors (MORs) induces side effects of opioids. In this study, we investigated the possible improvement of the immune system in tumour-bearing mice by systemic administration of the peripheral MOR antagonist naldemedine. METHODS: The inhibitory effect of naldemedine on MOR-mediated signalling was tested by cAMP inhibition and ß-arrestin recruitment assays using cultured cells. We assessed possible changes in tumour progression and the number of splenic lymphocytes in tumour-bearing mice under the repeated oral administration of naldemedine. RESULTS: Treatment with naldemedine produced a dose-dependent inhibition of both the decrease in the cAMP level and the increase in ß-arrestin recruitment induced by the MOR agonists. Repeated treatment with naldemedine at a dose that reversed the morphine-induced inhibition of gastrointestinal transport, but not antinociception, significantly decreased tumour volume and prolonged survival in tumour-transplanted mice. Naldemedine administration significantly decreased the increased expression of immune checkpoint-related genes and recovered the decreased level of toll-like receptor 4 in splenic lymphocytes in tumour-bearing mice. CONCLUSIONS: The blockade of peripheral MOR may induce an anti-tumour effect through the recovery of T-cell exhaustion and promotion of the tumour-killing system.

Children's understanding of friendship formation caused by gossip.

Previous studies with adults argued that gossiping contributes to friendship formation. Although some evidence suggests that gossip is also ubiquitous in children's lives, whether children understand its effect has not been investigated. In this study, we examined how children aged 6-10 years understand the effect of gossip on friendship formation between two individuals. They heard six vignettes where a protagonist heard a piece of gossip about a target from a gossip spreader and answered whether the protagonist wanted to be friends with the spreader. In these vignettes, we manipulated the valence of gossip (positive/negative) and the shared mindset between the protagonist and the gossip spreader (having the same/opposite/no opinion about the gossip target). We found that the children thought that the protagonist wanted to form a friendship with the person who spread positive gossip, but the extent of the protagonist's desire to befriend the gossip spreader depended on their shared mindset. On the other hand, the children thought that the protagonist wanted to befriend the person who spread negative gossip when the protagonist had the same opinion about the target. These findings suggest that the children's inference of friendship formation caused by gossip depended on the valence of gossip and whether a shared mindset existed between the two individuals. This is the first evidence that reveals how children understand the social consequences of gossiping.

Children are sensitive to the number of sources when relying on gossip.

Gossip allows children to effectively identify cooperative or trustworthy partners. However, the risk of being deceived must be faced because gossip may be false. One clue for determining gossip's veracity is the number of its sources since multiple informants spreading identical reputational information about others might imply that another's moral traits are viewed unanimously among members of a social group. We investigated whether 7-year-olds (N = 108) would trust gossip from multiple independent sources. In our study, they received multiple pieces of positive/negative reputational information about one agent and neutral information about another agent by gossip from either single or multiple informants. Then they allocated rewards to and chose rewards from the gossip targets. The 7-year-olds acted upon positive gossip from multiple informants and did not rely on positive gossip from a single informant. By contrast, they relied on negative gossip regardless of the number of informants. In either valence, however, they were more likely to allocate rewards based on gossip from multiple informants than a single informant. This result indicates they are sensitive to an objective index, specifically the number of sources, for judging the veracity of gossip.

The impact of positive and negative testimony on children's attitudes toward others.

Children can identify who is benevolent or malevolent not only through first-hand experiences and observations but also from the testimony of others. In this study, we investigated whether 5- and 7-year-olds (N = 128) would form their attitudes toward others after hearing testimony about that person's past moral behavior and whether the valence of testimony would differently influence the children. In the positive condition, half of the participants gained information about three puppets: puppet A's prosocial behavior by their own first-hand observation, testimony about puppet B's past prosocial behavior, and testimony about puppet C's past neutral behavior. In the negative condition, the other half also learned information about the three puppets: puppet A's antisocial behavior by their own first-hand observation, testimony about puppet B's past antisocial behavior, and testimony about puppet C's past neutral behavior. Then they engaged in tasks that measured their behavioral attitudes toward the puppets and evaluated the goodness of each puppet to assess their attitudes at a cognitive level. Our results concluded that the children form their behavioral attitudes toward others based on testimony starting at the age of 7, and attitude formation at the cognitive level based on testimony is seen at age 5. Negative testimony, rather than positive testimony, influences the children's attitudes toward others. In addition, the 7-year-olds' use of testimony differs depending whether they are the allocators or the receivers of rewards. Our findings deepen understanding of how children rely on the verbal information around themselves when they navigate interactions with others.

No Evidence for the Watching-Eyes Effect on Human Impulsivity.

People often become more altruistic when they think or feel that someone is watching them. Known as the "watching-eyes effect," this is argued to be caused by the motivation to gain and maintain a positive social reputation as an altruistic individual (the "reputation seeking" mechanism). However, an alternative mechanism underlying the watching-eyes effect could be that people suppress their impulsive tendency to pursue benefit rather than increase their altruism, and this may lead to apparent increases in altruistic tendencies. This "suppressing impulsivity" mechanism is considered intrapersonal rather than socially mediated which is associated with "reputation seeking." We examined whether the suppressing impulsivity mechanism would be associated with the watching-eyes effect by measuring participants' impulsivity in the presence of watching-eyes stimuli. In a controlled experiment, we presented life-size pictures of human faces with a direct gaze on a monitor in front of participants taking part in a time-discounting task. Two types of faces, "in-group" (faces of participants' classmates) and "out-group" (unfamiliar faces) were presented to examine the effect of social attribution. We used a flower picture as a control stimulus. In the time-discounting task, participants chose one of two options: a small amount of money that they could get immediately or a larger amount of money that they could get after a given time interval. The results showed no significant difference in participants' time-discount rate regardless of the types of stimuli presented during the time-discount task. A post-task questionnaire confirmed that the participants were aware of the presented stimuli and revealed that they paid more attention to the in-group stimuli than to the out-group and flower stimuli, though this difference in attentive states had no effect on their impulsivity during the task. These results suggest that suppressing impulsivity is not a plausible mechanism for the watching-eyes effect. The null effect for the difference between the in-group and out-group stimuli also supports this conclusion. Thus, it is plausible that the watching-eyes effect is caused by the human tendency to boost social reputation and can be mediated by the social relationship with others.