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Intestinal homeostasis relies on a continuous dialogue between the commensal bacteria and the immune system. Natural killer T (NKT) cells, which recognize CD1d-restricted microbial lipids and self-lipids, contribute to the regulation of mucosal immunity, yet the mechanisms underlying their functions remain poorly understood. Here, we demonstrate that NKT cells respond to intestinal lipids and CD11c(+) cells (including dendritic cells (DCs) and macrophages) are essential to mediate lipid presentation within the gut ultimately controlling intestinal NKT cell homeostasis and activation. Conversely, CD1d and NKT cells participate in the control of the intestinal bacteria composition and compartmentalization, in the regulation of the IgA repertoire and in the induction of regulatory T cells within the gut. These changes in intestinal homeostasis require CD1d expression on DC/macrophage populations as mice with conditional deletion of CD1d on CD11c(+) cells exhibit dysbiosis and altered immune homeostasis. These results unveil the importance of CD11c(+) cells in controlling lipid-dependent immunity in the intestinal compartment and reveal an NKT cell-DC crosstalk as a key mechanism for the regulation of gut homeostasis.

Ostracism--being excluded and ignored--is painful and threatens needs for belonging, self-esteem, control and meaningful existence. Many studies have shown that immediate responses to ostracism tend to be resistant to moderation. Once ostracized individuals are able to reflect on the experience, however, personality and situational factors moderate recovery speed and behavioural responses. Because attachment orientation is grounded in perceptions of belonging, we hypothesized that attachment orientation would moderate both immediate and delayed reactions to laboratory-induced ostracism. Participants from individualistic or collectivistic cultures were either included or ostracized in a game of Cyberball, a virtual ball-toss game. In both cultures, we found that compared to more securely attached individuals, more avoidant participants were less distressed by ostracism, but more distressed by inclusion. It is suggested that over and beyond differences in culture, individuals who avoid meaningful attachment may be less affected by ostracism.

Being ostracized by others threatens the satisfaction of fundamental needs, although less so when individuals first are reminded of a close relationship. What remains unknown is the effect of being ostracized directly by a relationship partner, which may vary depending on attachment security. We examined how a partner's involvement in ostracism affects need satisfaction and relationship evaluations, and explored attachment security. One hundred and twenty-seven couple members played Cyberball in a between-subjects experiment manipulating ostracism and partner involvement. Need satisfaction was more strongly affected by the partner's presence (vs. absence). Individuals evaluated their relationship more negatively as a function of partner ostracism and high attachment avoidance. Attachment anxiety was associated with lower need satisfaction. The results highlight relational expectations and influences on belonging needs.

Ostracism – being excluded and ignored – can cause psychological distress. There has been little research examining how a person's concept of self might influence the effects of ostracism. In the current study, we sought to examine the effect of self-construal on the distress created by ostracism. Specifically, we assessed the potential moderating effects of self-construal on both the initial distress of ostracism and the coping process. Participants, recruited in China, completed a self-construal measure and were either included or ostracized in an online ball-tossing game. They then reported need-satisfaction both immediately following the game and after a filler task. Interdependent self-construal facilitated participants' recovery from some of the negative effects of ostracism, but did not have an impact on the initial pain.

Social pain has been shown to be more easily re-lived than physical pain. This study further examined whether social pain could be more easily pre-lived or pre-experienced than physical pain. Participants were instructed to pre-live a socially or physically painful event and report their feelings of pain. Consistent with our hypotheses, social pain is easily pre-lived, but physical pain is not. In addition, individuals with more vivid mental imageries reported higher levels of pain after pre-living a socially painful event than those with less vivid mental imagery; such a difference was not observed after pre-living a physically painful event. The discussion was centered on the theoretical and metrological implications of these findings. Copyright © 2012 John Wiley & Sons, Ltd.

Current theories suggest that social and physical pain overlap in their neurological and physiological outcomes. We investigated how social and physical pain overlap in their psychological responses by testing the hypothesis that both social and physical pain would thwart satisfaction on four human needs, worsen mood, and increase desire to aggress. In Experiment 1, recalling an experience of social or physical pain produced overlapping effects in the form of thwarted self-esteem and control needs and increased negative affect and desire to aggress. In Experiment 2, we induced social (Cyberball ostracism) or physical pain (cold pressor) within the laboratory session, and found that both pain types produced feelings of being ignored and excluded, and thwarted belonging, self-esteem, control, and meaningful existence. Our results provide further support to pain overlap theories and indicate that social and physical pain cause common psychological consequences, resulting in new ways to understand and manage pain. Copyright © 2011 John Wiley & Sons, Ltd. There is growing evidence in the literature showing that physical pain, the pain caused by a physical injury, and social pain, the pain caused by the threat or actual loss of a social connection (MacDonald & Leary, 2005), share a common neural system. Yet, it is still unclear whether the physiological overlap between the pain types also implies an overlap in their psychological responses. The present paper aims to fill this gap. We examined whether the social/physical pain overlap results in common psychological responses as well. The physiological overlap underlying physical and social pain was initially proposed by Panksepp (1998). Panksepp found that, besides reducing the experience of pain, the administration of an opiate also reduced crying behavior in animals that were socially isolated (Panksepp, Herman, Conner, Bishop, & Scott, 1978). Following Panksepp and colleagues’ early suggestion, several authors investigated whether similar neural brain circuitries are delegated to detect, process, and regulate both social and physical pain in social animals and humans (DeWall et al., 2010; Eisenberger, Lieberman, & Williams, 2003).

Previous research indicates that rejection by a group causes aggressive responses. However, in these previous studies, rejected participants were led to believe that they were liked and accepted before the rejection; likely, this rejection was highly unanticipated. Sociometer theory (Leary et al., 1995) proposes the existence of a psychological mechanism (a "sociometer") that enables individuals to detect potential rejection via others' reactions; a properly working sociometer affords a person predictive control over an interaction. We hypothesized the lack of predictive control inherent in previous rejection studies was a critical contributor to participants' aggressive responses; predictive control should lead to decreased aggression. To test this, we manipulated predictive control by varying confederate behavior toward participants before a rejection manipulation. Results indicate that unpredictable rejection undermined participants' belief that they could predict other's behavior (i.e., led to the perception of a broken sociometer) and led to higher levels of aggression.

To be ostracized is to be ignored and excluded. How does ostracism affect individuals? Considerable research has now shown that the initial (reflexive) reactions to even the most minimal forms of ostracism are painful and distressing. Fundamental needs of belonging, self-esteem, control, and meaningful existence are thwarted; sadness and anger increase. These effects emerge despite individual differences or situational factors that should lead logically to easy dismissal. With time to appraise the ostracism episode, individuals become differentially sensitized based on (i) the specific needs that are thwarted, (ii) their own individual differences, and (iii) their assessment of who ostracizes and why. These differences lead to need-restorative behaviors that range from being overly socially attentive and susceptible to influence to being aggressive and antisocial.

Previous research has shown that ostracism even by outgroup members is aversive. In this study we examined whether ostracism by a particular type of outgroup, a despised outgroup, was sufficient to inflict emotional distress. We manipulated ostracism using Cyberball, an on-line ball toss game. Ostracized participants reported lower levels of belonging, self-esteem, control, and meaningful existence, and more negative mood, than included participants. Moreover, ostracism by despised outgroup members was no less aversive than ostracism by rival outgroup or ingroup members. Participants differentiated between the groups, however; ostracized individuals reported greater outgroup negativity than included participants only when their co-players were members of the despised outgroup. We interpret these results as evidence for the powerful impact of ostracism and the potential importance of distinguishing between qualitatively different outgroups. Copyright © 2006 John Wiley & Sons, Ltd.

Studying survivors of natural disasters and traumatic events provides a unique opportunity to address some of the important and difficult questions in psychology and other social sciences. However, such an opportunity does not come without challenges. Several methodological challenges to studying survivors of natural disasters are discussed, including recruiting participants, choosing appropriate procedures, and the safety of data collectors. Several ethical issues are also presented, such as the ability of participants to make decisions, the impact of participating, and the importance of informed consent. In addition, approaches are suggested that help to deal with these methodological and ethical challenges. We conclude that while attention must be focused on methodological and ethical considerations, research stemming from natural disasters should be employed to answer important basic and applied conceptual questions and address issues of practice and policy, while assuring that steps have been taken to protect participants and that the potential risks are minimal.