Experimental evidence suggests intergroup relations are, by default, neutral rather than aggressive.

The target article offers a game-theoretical analysis of primitive intergroup aggression (i.e., raiding) and discusses difficulties in achieving peace. We argue the analysis does not capture the actual strategy space, missing out "do-nothing." Experimental evidence robustly shows people prefer doing nothing against out-group members over cooperating with/attacking them. Thus, the target article overestimates the likelihood of intergroup aggression.

Towards the elucidation of evolution of out-group aggression.

We focus on the implications of De Dreu and Gross's findings for the evolutionary perspective on out-group aggression and in-group cooperation. Although their experimental protocols are potentially useful in determining the origins of out-group aggression in humans, they so far provide inconclusive evidence only. We suggest ways of furthering our understanding of the connection between parochial cooperation and intergroup conflict.

Rejection of unfair offers in the ultimatum game is no evidence of strong reciprocity.

The strong reciprocity model of the evolution of human cooperation has gained some acceptance, partly on the basis of support from experimental findings. The observation that unfair offers in the ultimatum game are frequently rejected constitutes an important piece of the experimental evidence for strong reciprocity. In the present study, we have challenged the idea that the rejection response in the ultimatum game provides evidence of the assumption held by strong reciprocity theorists that negative reciprocity observed in the ultimatum game is inseparably related to positive reciprocity as the two sides of a preference for fairness. The prediction of an inseparable relationship between positive and negative reciprocity was rejected on the basis of the results of a series of experiments that we conducted using the ultimatum game, the dictator game, the trust game, and the prisoner's dilemma game. We did not find any correlation between the participants' tendencies to reject unfair offers in the ultimatum game and their tendencies to exhibit various prosocial behaviors in the other games, including their inclinations to positively reciprocate in the trust game. The participants' responses to postexperimental questions add support to the view that the rejection of unfair offers in the ultimatum game is a tacit strategy for avoiding the imposition of an inferior status.

Apathy/depression, but not subjective fatigue, is related with cognitive dysfunction in patients with multiple sclerosis.

BACKGROUND: Cognitive impairment could affect quality of life for patients with multiple sclerosis (MS), and cognitive function may be correlated with several factors such as depression and fatigue. This study aimed to evaluate cognitive function in Japanese patients with MS and the association between cognitive function and apathy, fatigue, and depression. METHODS: The Brief Repeatable Battery of Neuropsychological tests (BRB-N) was performed in 184 Japanese patients with MS and 163 healthy controls matched for age, gender, and education. The Apathy Scale (AS), Fatigue Questionnaire (FQ), and Beck Depression Inventory Second Edition (BDI-II) were used to evaluate apathy, fatigue, and depression, respectively. Student's t-test was used to compare MS patients and healthy controls. Correlations between two factors were assessed using the Pearson correlation test, and multiple regression analysis was used to evaluate how much each factor affected the BRB-N score. RESULTS: In all BRB-N tests, patients with MS scored significantly lower than controls, and the effect size of symbol digit modalities test was the highest among the 9 tests of the BRB-N. Patients with MS had higher AS (p < 0.001), FQ (p < 0.0001), and BDI-II (p < 0.0001) scores than controls. In patients with MS, scores on most of the BRB-N tests correlated with scores on the AS and BDI-II; however, there was little correlation between scores on the BRB-N tests and those on the FQ. CONCLUSIONS: Cognitive function was impaired, particularly information-processing speed, and decreased cognitive function was correlated with apathy and depression in Japanese patients with MS. Despite the association between cognitive variables and depression/apathy, cognitive function was impaired beyond the effect of depression and apathy. However, subjective fatigue is not related with cognitive impairment. Taken together, this suggests that different therapeutic approaches are needed to improve subjective fatigue and cognition, and thereby quality of life, in patients with MS.

Structural equation modeling of factors contributing to quality of life in Japanese patients with multiple sclerosis.

BACKGROUND: To improve quality of life (QOL) in patients with multiple sclerosis (MS), it is important to decrease disability and prevent relapse. The aim of this study was to examine the causal and mutual relationships contributing to QOL in Japanese patients with MS, develop path diagrams, and explore interventions with the potential to improve patient QOL. METHODS: Data of 163 Japanese MS patients were obtained using the Functional Assessment of MS (FAMS) and Nottingham Adjustment Scale-Japanese version (NAS-J) tests, as well as four additional factors that affect QOL (employment status, change of income, availability of disease information, and communication with medical staff). Data were then used in structural equation modeling to develop path diagrams for factors contributing to QOL. RESULTS: The Expanded Disability Status Scale (EDSS) score had a significant effect on the total FAMS score. Although EDSS negatively affected the FAMS symptom score, NAS-J subscale scores of anxiety/depression and acceptance were positively related to the FAMS symptom score. Changes in employment status after MS onset negatively affected all NAS-J scores. Knowledge of disease information improved the total NAS-J score, which in turn improved many FAMS subscale scores. Communication with doctors and nurses directly and positively affected some FAMS subscale scores. CONCLUSIONS: Disability and change in employment status decrease patient QOL. However, the present findings suggest that other factors, such as acquiring information on MS and communicating with medical staff, can compensate for the worsening of QOL.

Punishment in the public goods game is evaluated negatively irrespective of non-cooperators' motivation.

The evolution of human cooperation toward strangers remains puzzling. While the punishment of non-cooperators is a possible explanation, whether punishments can help cooperation evolve depends on how people evaluate punishers. Thus, it is of vital importance to elucidate the perception of punishers. Previous studies have found that punishment is evaluated differently in different contexts; punishers are negatively and positively evaluated in the public goods game with punishment (PGG-P) and in the third-party punishment game (TPP), respectively. To disentangle the mixed evidence, our research focused on motivations for non-cooperation and examined whether different motivations for non-cooperation could explain the inconsistent findings. We hypothesized that people positively evaluate punishers when they punish those who non-cooperated to exploit others (greed), e.g., in a TPP situation. Contrastingly, people negatively evaluate punishers when they punish those who non-cooperated to avoid exploitation (fear), e.g., in a PGG-P situation. If so, in either game, punishers would be evaluated positively in situations where greed dominates, and negatively in situations where fear dominates the non-cooperation motivation. To test this, we conducted two online experiments with hypothetical scenarios in which the decision-making order was used to manipulate the motivations of non-cooperators. The results of Study 1 (N = 240) using only PGG-P and Study 2 (N = 602) using both PGG-P and TPP showed that the non-cooperation motivation did not have a significant effect on the evaluations of punishers and non-punishers. Punishers (vs non-punishers) were evaluated negatively in PGG-P and positively in TPP regardless of the decision-making order of non-cooperation. We discussed the role of higher-order information in the evaluation of punishment.

Differences in and associations between belief in just deserts and human rights restrictions over a 3-year period in five countries during the COVID-19 pandemic.

Discrimination, which arose during the coronavirus disease 2019 outbreak, is a global public health issue. This study aimed to provide fundamental knowledge in proposing control measures to mitigate discrimination. We focused on two psychological variables: belief in just deserts (BJD, i.e., the belief that the infected individual deserves to be infected), a psychological factor that potentially promotes discrimination and prejudice, and human rights restrictions (HRR; i.e., the degree of individuals' agreement with government restrictions on citizens' behavior during emergencies). Differences in these items, as well as their annual trends from 2020 to 2022, were examined in Japan, the United States (US), the United Kingdom (UK), Italy, and China. In addition, the associations between BJD and HRR by country and year and the direction of the associations between them in Japan and Italy were analyzed. Online surveys were conducted annually, with 392-518 participants per country and year. The BJD was higher in Japan and lower in the UK. BJD increased significantly from 2020 to 2021 in all countries, except in China. Meanwhile, HRR was higher in China and lower in Japan. The HRR decreased from 2020 to 2021 in Japan and decreased from 2020 to 2022 in the US, the UK, and Italy. There were significant positive associations between BJD and HRR in Japan and Italy. Cross-lagged panel models revealed positive bidirectional associations between BJD and HRR in Japan and Italy, respectively, indicating that the HRR declined among those with weak BJD and that the BJD increased among those with high HRR. In Japan and Italy, the dissemination of public messages targeting those with a high HRR in the early stages of an infectious disease outbreak could potentially mitigate the adverse impact of the BJD, eventually reducing discrimination, especially when the infection is not attributed to the fault of the infected individuals.

Health-related quality of life in Japanese patients with multiple sclerosis.

OBJECTIVES: Neurological disabilities, especially physical issues, can adversely affect the daily lives of people with multiple sclerosis (MS) and negatively impact their health-related quality of life (HRQOL). On the other hand, physical and psychiatric symptoms are variable in people with MS, and QOL can be influenced by cultural and educational background. This study aimed to evaluate the association of HRQOL with disabilities, fatigue, and depression in Japanese subjects with MS. METHODS: Evaluation of HRQOL, fatigue, and depression was performed in 184 Japanese individuals with MS, using the Functional Assessment of MS (FAMS), Fatigue Severity Scale (FSS), and Beck Depression Inventory-Second Edition (BDI-II), respectively. RESULTS: Multiple linear regression analysis demonstrated negative correlations of the Expanded Disability Status Scale (EDSS) with scores on the FAMS subscales of mobility, symptoms, thinking and fatigue, total FAMS, and additional concerns. The FSS score had negative correlations with mobility, symptoms, emotional well-being, thinking and fatigue, total FAMS, and additional concerns. There were negative correlations between BDI-II scores and all items of FAMS. CONCLUSIONS: HRQOL had relatively close correlations with disabilities and fatigue, and depression had an especially close relationship with HRQOL.

Null results for the steal-framing effect on out-group aggression.

Whether intergroup conflict is a necessary condition for the evolution of human prosociality has been a matter of debate. At the center of the debate is the coevolutionary model of parochial altruism-that human cooperation with in-group members has coevolved with aggression toward out-group members. Studies using the intergroup prisoner's dilemma-maximizing difference game to test the model have repeatedly shown that people do not exhibit out-group aggression, possibly because of an inappropriate operationalization and framing of out-group aggression. The coevolutionary model predicts out-group aggression when the actor understands that it will lead to the in-group's benefit. However, in the game, such an aspect of out-group aggression that benefits the in-group is typically not well communicated to participants. Thus, this study tested the hypothesis that out-group aggression in the game would be promoted by a framing that emphasizes that attacking out-group members enhances the in-group's gain. Results of two laboratory experiments with 176 Japanese university students in total showed that such a framing did not promote out-group aggression and individuals invested more money to cooperate with in-group members only, avoiding the strategy of cooperating with in-group members to harm out-group members. These results do not support the coevolutionary model.

Willingness to be the recipient during the dictator game.

OBJECTIVE: Researchers have investigated human altruism toward strangers for decades, using economic games such as the dictator game (DG) in their experiments. However, factors that cause the allocating behavior exhibited by those participants willing to be recipients in the DG have not been identified and the psychological mechanism of avoiding decision-making in economic games has not been widely addressed in previous studies. This study aimed to replicate previous findings regarding the number of people who are willing to be assigned the role of recipient and their allocation behavior and to explore why they share more than people who are willing to be dictators. RESULTS: We demonstrate that there are people willing to be assigned the role of the recipient, rather than the role of the dictator during the dictator game. In addition, we find evidence indicating that people who are willing to be recipients behave more altruistically in the dictator game than those who prefer to be dictators. Based on our results, we argue that willingness to be a recipient, in relation to the psychological unwillingness to assume responsibility and reputational concerns, is a strategic consideration.

Positive reputation for altruism toward future generations regardless of the cost for current others.

Recently, altruism toward future generations (future altruism) has become a hot research topic. Although future altruism has been observed in several previous experiments, it is not yet clear when and why people are more likely to engage in future altruism. Drawing upon the empirical literature of reputation and cooperation, we predicted that future altruism brings reputational disadvantages. Accordingly, we investigated whether future altruism was evaluated positively or negatively by others in the current generation in two vignette studies (total N = 1,237). Contrary to our initial prediction, we found that future altruism was positively evaluated even when it decreased the payoff of the members of the current generation. The difference in the evaluation of future altruism, as opposed to unsustainable current-generation focused behavior, was most pronounced when people do not know how a future altruist allocates rewards among individuals in the current generation. However, the positive evaluation of future altruism did not stem from the expectation that future altruists would also be altruistic toward the current generation. These results indicated that reputational benefits (i.e., positive reputation from others in the current generation) promote future altruism.

Correlation of the symbol digit modalities test with the quality of life and depression in Japanese patients with multiple sclerosis.

BACKGROUND: This study aimed to evaluate the association between cognitive impairment and health-related quality of life (HRQOL), fatigue, and depression in Japanese patients with multiple sclerosis (MS). METHODS: The Brief International Cognitive Assessment for MS (BICAMS) was performed in 184 Japanese patients with MS. The Functional Assessment of MS (FAMS), Fatigue Severity Scale (FSS), and Beck Depression Inventory-Second Edition (BDI-II) were used to evaluate HRQOL, fatigue, and depression, respectively. RESULTS: Multiple linear regression analysis demonstrated positive correlations of the Symbol Digit Modalities Test (SDMT) with the scores on the FAMS subscales of mobility, symptoms, emotional well-being, and additional concerns and with the total FAMS score even after controlling for the Expanded Disability Status Scale score, age at examination, and duration of education. The SDMT score in the BICAMS battery had negative correlations with the BDI-II score, as revealed by multiple linear regression analysis. None of the three tests in the BICAMS had any correlation with the FSS score. CONCLUSION: The SDMT has a significant relationship with HRQOL and depression in Japanese patients with MS.

Impact and characteristics of quality of life in Japanese patients with multiple sclerosis.

PURPOSE: To evaluate health-related quality of life (HRQOL) in Japanese patients with multiple sclerosis (MS) and investigate associations between the results of these QOL assessments and disease severity. METHODS: One-hundred sixty-three Japanese MS patients completed a questionnaire battery comprising the Functional Assessment of MS (FAMS), the Nottingham Adjustment Scale-Japanese version (NAS-J), and the European QOL scale (EQ-5D). Additional five factors affecting QOL as identified by MS patients in a focus group interview were also investigated: employment status, change of income, availability of disease information, communication with medical staff, and care received. Disease severity was determined using the Expanded Disability Status Scale (EDSS). RESULTS: There was a strong negative correlation of the subscale scores for mobility, symptoms, emotional well-being, thinking and fatigue, and additional concerns on the FAMS with EDSS score. For the NAS-J, only acceptance of the condition was correlated with disease severity. Among the five additional aspects of the condition identified by patients, employment status, income, and disease information were shown to be important for maintaining QOL in patients with MS. CONCLUSIONS: Support for finding employment and having increased or maintained household income and readily available information about the disease contribute to improving QOL in Japanese MS patients.

Pathogen Threat and In-group Cooperation.

Disease-causing parasites and pathogens play a pivotal role in intergroup behavior. Previous studies have suggested that the selection pressure posed by pathogen threat has resulted in in-group assortative sociality, including xenophobia and in-group favoritism. While the current literature has collated numerous studies on the former, strikingly, there has not been much research on the relationship between pathogen threat and in-group cooperation. Drawing upon prior studies on the function of the behavioral immune system (BIS), we argued that the BIS might facilitate cooperation with in-group members as a reactive behavioral immune response to pathogen threat. More specifically, we held that individuals might utilize cooperative behavior to ensure that they can receive social support when they have contracted an infectious disease. We reviewed existing findings pertaining to the potential role of the BIS in in-group cooperation and discussed directions for future studies.

People prefer joint outcome prosocial resource distribution towards future others.

Today, developing and maintaining sustainable societies is becoming a notable social concern, and studies on altruism and prosociality toward future generations are increasing in importance. Although altruistic behaviors toward future generations have previously been observed in some experimental situations, it remains unknown whether prosocial preferences toward future others are based on equality or joint outcome orientations. In the present research, we exploratorily investigated preferences regarding resource distribution by manipulating the time points (i.e., present/future) of the participants and their imaginary partners. The results indicate that prosocial preference toward future others was as strong as that toward present others and seemed to be based on a joint outcome prosocial preference. Notably, when participants and their partners were at different time points, participants preferred to leave resources for the persons in the future. The findings indicate that the type of altruistic preference toward future others may differ from that toward present others, which is mainly equality.

Salivary testosterone levels and autism-spectrum quotient in adults.

OBJECTIVES: The purpose of this study is to examine the relationship between salivary testosterone levels and autistic traits in adults. METHODS: A total of 92 male and female adults participated in the present study. Their salivary testosterone level (T) and score of Japanese version of Autism-spectrum Quotient (AQ) were assessed to examine the relationship between salivary testosterone level and autistic traits in adults. RESULTS: We observed a positive correlation between T and AQ in a group of both sexes. The correlation disappeared when we conducted correlation analysis by sex. However, although there was no sex difference in the score of the subscale of attention switching, attention switching was related to T. CONCLUSIONS: Although the relationship between T and AQ may mainly result from sex differences, the subscale of attention switching may be modulated by testosterone.

Salivary alpha-amylase levels and big five personality factors in adults.

OBJECTIVES: Salivary alpha-amylase (sAA) has been utilized as a non-invasive measure of sympathoadrenal medullary (SAM) activation. Little is known regarding the relationship between personality inventories and baseline sAA. This study was designed to examine the relationships between the scores of big five inventory (BFI) factors, age, and sAA in adults (aged twenty to seventy years old). METHODS: We assessed 97 participants' BFI scores and sAA. The correlations between the BFI factor scores and sAA were examined. RESULTS: We observed (1) a positive correlation between Neuroticism and sAA, and a negative correlation between Agreeableness and sAA and (2) a positive correlation between age and sAA. These correlations between BFI scores and sAA remained significant after controlling for age. After controlling for age, all BFI factors except Conscientiousness were related to sAA. CONCLUSIONS: Subjects with high Neuroticism and low Extraversion, Agreeableness and Openness may have high sAA. sAA has been demonstrated to be useful for examining the relationship between adrenergic activity and personality, in a non-invasive manner.

Stress hormones predict hyperbolic time-discount rates six months later in adults.

OBJECTIVES: Stress hormones have been associated with temporal discounting. Although time-discount rate is shown to be stable over a long term, no study to date examines whether individual differences in stress hormones could predict individuals' time-discount rates in the relatively distant future (e.g., six month later), which is of interest in neuroeconomics of stress-addiction association. METHODS: We assessed 87 participants' salivary stress hormone (cortisol, cortisone, and alpha-amylase) levels and hyperbolic discounting of delayed rewards consisting of three magnitudes, at the time-interval of six months. For salivary steroid assays, we employed a liquid chromatography/ mass spectroscopy (LC/MS) method. The correlations between the stress hormone levels and time-discount rates were examined. RESULTS: We observed that salivary alpha-amylase (sAA) levels were negatively associated with time-discount rates in never-smokers. Notably, salivary levels of stress steroids (i.e., cortisol and cortisone) negatively and positively related to time-discount rates in men and women, respectively, in never-smokers. Ever-smokers' discount rates were not predicted from these stress hormone levels. CONCLUSIONS: Individual differences in stress hormone levels predict impulsivity in temporal discounting in the future. There are sex differences in the effect of stress steroids on temporal discounting; while there was no sex defference in the relationship between sAA and temporal discounting.

[Accuracy of judgment about others' cooperative behavior: effects of attractiveness and facial expressiveness].

Cooperation in interdependent relationships is based on reciprocity in repeated interactions. However, cooperation in one-shot relationships cannot be explained by reciprocity. Frank, Gilovich, & Regan (1993) argued that cooperative behavior in one-shot interactions can be adaptive if cooperators displayed particular signals and people were able to distinguish cooperators from non-cooperators by decoding these signals. We argue that attractiveness and facial expressiveness are signals of cooperators. We conducted an experiment to examine if these signals influence the detection accuracy of cooperative behavior. Our participants (blind to the target's behavior in a Trust Game) viewed 30-seconds video-clips. Each video-clip was comprised of a cooperator and a non-cooperator in a Trust Game. The participants judged which one of the pair gave more money to the other participant. We found that participants were able to detect cooperators with a higher accuracy than chance. Furthermore, participants rated male non-cooperators as more attractive than male cooperators, and rated cooperators more expressive than non-cooperators. Further analyses showed that attractiveness inhibited detection accuracy while facial expressiveness fostered it.

Social dominance orientation as an obstacle to intergroup apology.

Social Dominance Orientation (SDO) has engaged the interest of social and personality psychologists as it has deep implications for the psychology of intergroup conflict, particularly regarding factors such as prejudice and discrimination, as well as international conflict resolution. Nevertheless, few studies have directly assessed how SDO relates to intergroup reconciliation. This study (effective N = 819) measured participants' SDO along with their attitudes toward various governmental apologies to test the hypothesis that SDO is associated with unwillingness to issue intergroup apologies. The results showed that SDO was negatively correlated with supportive attitudes toward government-issued international apologies. This negative correlation remained intact after controlling for the effects of political conservatism and militarism.