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.

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, , the belief that the infected individual deserves to be infected), a psychological factor that potentially promotes discrimination and prejudice, and human rights restrictions (HRR; , the degree of individuals' agreement with government restrictions on citizens' behavior during emergencies).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Validation of the Brief International Cognitive Assessment for Multiple Sclerosis in Japan.

Background: The Brief International Cognitive Assessment for MS (BICAMS) is a practical battery for measuring cognitive function in multiple sclerosis (MS).

Objectives: We aimed to validate a Japanese version of the BICAMS in patients with MS and healthy controls.

Methods: The Symbol Digit Modalities Test (SDMT), the California Verbal Learning Test-Second Edition (CVLT2) and the Brief Visuospatial Memory Test Revised (BVMTR) were administered to 156 patients with MS and 126 healthy controls (HCs).

Providing compensation promotes forgiveness for replaceable, but not irreplaceable, losses.

The present study aimed to examine how the replaceability of a loss moderates the effectiveness of compensation. In Study 1, we sampled real-life experiences of experiential loss, material loss, or loss of materials to which the victims had special attachment, and assayed subsequent feelings toward the transgressor who caused the loss. The results showed that for those who reported losses of an experience or cherished material object, perpetrators' offers of compensation did not facilitate forgiveness.

War or Peace? How the Subjective Perception of Great Power Interdependence Shapes Preemptive Defensive Aggression.

Why do great powers with benign intentions end up fighting each other in wars they do not seek? We utilize an incentivized, two-person "Preemptive Strike Game" (PSG) to explore how the subjective perception of great power interdependence shapes defensive aggression against persons from rival great powers. In Study 1, college students from the United States ( = 115), China ( = 106), and Japan ( = 99) made PSG decisions facing each other. This natural experiment revealed that Chinese and Japanese participants (a) made more preemptive attacks against each other and Americans than against their compatriots, and that (b) greater preexisting perceptions of bilateral competition increased intergroup attack rates.

Intergroup Biases in Fear-induced Aggression.

Using a recently created preemptive strike game (PSG) with 176 participants, we investigated if the motivations of spite and/or fear promotes aggression that requires a small cost to the aggressor and imposes a larger cost on the opponent, and confirmed the earlier finding that fear does but spite does not promote intergroup aggression when the groups are characterized as minimal groups; additionally, the rate of intergroup aggression did not vary according to the group membership of the opponent. The PSG represents a situation in which both the motivations of spite and of fear can logically drive players to choose an option of aggression against an opponent. Participants decide whether or not to attack another participant, who also has the same capability.

Negotiating with the future: incorporating imaginary future generations into negotiations.

People to be born in the future have no direct influence on current affairs. Given the disconnect between people who are currently living and those who will inherit the planet left for them, individuals who are currently alive tend to be more oriented toward the present, posing a fundamental problem related to sustainability. In this study, we propose a new framework for reconciling the disconnect between the present and the future whereby some individuals in the current generation serve as an imaginary future generation that negotiates with individuals in the real-world present.

Preemptive Striking in Individual and Group Conflict.

In this study, we conducted a laboratory experiment to assess preemptive striking by and towards individuals or groups. In the framework of a preemptive strike game, we set the following four conditions: one person faced another person, one person faced a three-person group, a three-person group faced an individual, and a three-person group faced another three-person group. Previous studies have revealed that greed is activated when participants belong to a group, while fear is activated when participants interact with a group, and further, that attacking behaviors in the preemptive strike game are driven by fear.

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.

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).

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.

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).

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.

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.