The purpose of this study was to examine the effect of gratitude-expression skills on the benefactor in a dilemma situation. The method experimentally employed a confederate who met participants for the first time and executed gratitude-expression skills on them in a “Prisoner’s Dilemma Game” (PDG). An experimental group in which the confederate executed the gratitude-expression skills was compared with a control group in which the confederate did not do so. The results showed the experimental group had higher average and medium or higher effect size regarding the participants’ cooperative behavior in a PDG, the state of reciprocity consciousness, and interpersonal attraction for the confederate than the control group. This study found the positive effect of gratitude-expression skills on motivating the benefactor’s cooperative behavior and enhancing reciprocity consciousness and interpersonal attraction for the confederate even in a dilemma situation.

This study examined the association between socioeconomic status (SES) and anger expression in public situations. Specific studies have indicated that people with low SES tend to be aggressive. However, Park et al.(2013) demonstrated that in Japan, where there are strong norms favoring the control of emotional expression, people with high SES tend to express their anger. In this study, we assumed that psychological entitlement would engage their anger expression. We then hypothesized that psychological entitlement mediates relationships between SES and anger expression in public situations because highly entitled people might justify their anger and its expression. The results of Study 1 (n＝599) supported this hypothesis. Furthermore, the results of Study 2 (n＝598) indicated that people with high SES tended to evaluate their anger expression as justifiable due to high psychological entitlement, even though their opponents were blamless. We discussed the possibility that anger expression is promoted not only by a lack of self-control but also by justification for the anger.

Despite recent advancements in the theory and assessment of maximization, only outdated scales of maximization have been available in Japanese. Based on the two-component model of maximization, I translated into Japanese the Maximizing Tendency Scale and the alternative search subscale of the Maximization Inventory as indexes of high standards and alternative search, respectively, and also tested the validity of both scales. The results of exploratory and confirmatory factor analyses and item response theory revealed considerable internal reliability for both scales. The correlation analyses depicted a significant positive relationship between the Maximizing Tendency Scale and the Multidimensional Perfectionism Cognition Inventory as predicted, implying external validity of the Maximizing Tendency Scale as an index of high standards. Conversely, the Maximization Inventory did not correlate with the General Procrastination Scale, though a positive correlation was expected between alternative search and procrastination tendency. However, considering that correlations between the two factors of maximization and psychological traits were hardly reported, the result is not decisive.

Whether engaging in costly punishment can be an adaptive strategy by enhancing the punisher’s reputation is a crucial question in efforts to explain punishment behaviors. However, empirical findings on this question are mixed. Based on Raihani and Bshary’s (2015) argument, the current study empirically examined the possibility that how a punisher’s motives are estimated affects the reputation of the punisher. We employed a vignette experiment which was designed to make it simple for respondents to estimate each punisher’s motives. Each vignette described a defector in a social dilemma and a punisher who punished the defector using one of four types of punishment. Respondents then estimated the punisher’s motives and evaluated their impressions. The results revealed that the estimated motives depended on the type of punishment which the punishers utilized and that evaluations of punishers varied across the four types of punishment. Thus, the context in which punishment is employed may affect a punisher’s reputation, and this in turn might ultimately determine whether engaging in punishment is adaptive.

Previous research has shown that mind wandering improves creativity while it may simultaneously lead to mental illness. However, it has also been shown that some kinds of mind wandering are not related to negative mood or mental illness, and such mind wandering seems to improve creativity while maintaining good mental health. Therefore, our study examined what kinds of mind wandering are generated in highly creative people with a high level of mental health, focusing on daily life. Seventy-eight undergraduate and graduate students participated in the study. We measured indicators of creativity and mental health in the experiment room and measured the situation and features of mind wandering using an experience sampling method over three days. Results showed that highly creative people with a high level of mental health do not think much about social-related and future-related thought. In the future, we need to examine whether evoking MW that does not include things about others actually enhances creativity without inhibiting mental health.