IL-23 promotes TCR-mediated negative selection of thymocytes through the upregulation of IL-23 receptor and RORγt.

Transient thymic involution is frequently found during inflammation, yet the mode of action of inflammatory cytokines is not well defined. Here we report that interleukin-23 (IL-23) production by the thymic dendritic cells (DCs) promotes apoptosis of the CD4(hi)CD8(hi) double-positive (DP) thymocytes. A deficiency in IL-23 signalling interferes with negative selection in the male D(b)/H-Y T-cell receptor (TCR) transgenic mice. IL-23 plus TCR signalling results in significant upregulation of IL-23 receptor (IL-23R) expressed predominantly on CD4(hi)CD8(hi)CD3(+)αßTCR(+) DP thymocytes, and leads to RORγt-dependent apoptosis. These results extend the action of IL-23 beyond its peripheral effects to a unique role in TCR-mediated negative selection including elimination of natural T regulatory cells in the thymus.

Stereotype threat affects financial decision making.

The research presented in this article provides the first evidence that one's decision making can be influenced by concerns about stereotypes and the devaluation of one's identity. Many studies document gender differences in decision making, and often attribute these differences to innate and stable factors, such as biological and hormonal differences. In three studies, we found that stereotype threat affected decision making and led to gender differences in loss-aversion and risk-aversion behaviors. In Study 1, women subjected to stereotype threat in academic and business settings were more loss averse than both men and women who were not facing the threat of being viewed in light of negative stereotypes. We found no gender differences in loss-aversion behavior in the absence of stereotype threat. In Studies 2a and 2b, we found the same pattern of effects for risk-aversion behavior that we had observed for loss-aversion behavior. In addition, in Study 2b, ego depletion mediated the effects of stereotype threat on women's decision making. These results suggest that individuals' decision making can be influenced by stereotype concerns.

Ambient belonging: how stereotypical cues impact gender participation in computer science.

People can make decisions to join a group based solely on exposure to that group's physical environment. Four studies demonstrate that the gender difference in interest in computer science is influenced by exposure to environments associated with computer scientists. In Study 1, simply changing the objects in a computer science classroom from those considered stereotypical of computer science (e.g., Star Trek poster, video games) to objects not considered stereotypical of computer science (e.g., nature poster, phone books) was sufficient to boost female undergraduates' interest in computer science to the level of their male peers. Further investigation revealed that the stereotypical broadcast a masculine stereotype that discouraged women's sense of ambient belonging and subsequent interest in the environment (Studies 2, 3, and 4) but had no similar effect on men (Studies 3, 4). This masculine stereotype prevented women's interest from developing even in environments entirely populated by other women (Study 2). Objects can thus come to broadcast stereotypes of a group, which in turn can deter people who do not identify with these stereotypes from joining that group.

A nation challenged: the impact of foreign threat on America's tolerance for diversity.

Three experiments investigated how perceived foreign threats to the United States can influence Americans' endorsement of assimilation and multiculturalism as models for foreign and domestic intergroup relations. The initial study, conducted during the 6-month anniversary of the September 11, 2001, terrorist attacks (9/11), discovered that a diverse group of Americans preferred assimilation as a foreign policy and multiculturalism as a domestic policy. After reading that foreigners were supporting the dominant global status of the United States, however, Americans in Experiment 2 no longer expressed this preference for assimilation as a model for foreign intergroup relations. Experiment 3 discovered that Americans primed with 9/11 (i.e., a foreign threat) revealed higher levels of national identity than did those primed with the Columbine massacre (i.e., a domestic threat); moreover, level of national identity predicted support for multiculturalism as a domestic policy and assimilation as a foreign policy.

The ethics of characterizing difference: guiding principles on using racial categories in human genetics.

We are a multidisciplinary group of Stanford faculty who propose ten principles to guide the use of racial and ethnic categories when characterizing group differences in research into human genetic variation.

Social identity contingencies: how diversity cues signal threat or safety for African Americans in mainstream institutions.

This research demonstrates that people at risk of devaluation based on group membership are attuned to cues that signal social identity contingencies--judgments, stereotypes, opportunities, restrictions, and treatments that are tied to one's social identity in a given setting. In 3 experiments, African American professionals were attuned to minority representation and diversity philosophy cues when they were presented as a part of workplace settings. Low minority representation cues coupled with colorblindness (as opposed to valuing diversity) led African American professionals to perceive threatening identity contingencies and to distrust the setting (Experiment 1). The authors then verified that the mechanism mediating the effect of setting cues on trust was identity contingent evaluations (Experiments 2 & 3). The power of social identity contingencies as they relate to underrepresented groups in mainstream institutions is discussed.

The space between us: stereotype threat and distance in interracial contexts.

Four studies investigate the role that stereotype threat plays in producing racial distancing behavior in an anticipated conversation paradigm. It was hypothesized that the threat of appearing racist may have the ironic effect of causing Whites to distance themselves from Black conversation partners. In Study 1, participants distanced themselves more from Black partners under conditions of threat, and this distance correlated with the activation of a "White racist" stereotype. In Study 2, it was demonstrated that Whites' interracial distancing behavior was not predicted by explicit or implicit prejudice. Study 3 provides evidence that conceiving of interracial interactions as opportunities to learn may attenuate the negative consequences of threat for Whites. Study 4 found that Whites have conscious access to their experience of stereotype threat and that this awareness may mediate the relationship between threat and distance. These results are discussed within a broader discourse of racial distancing and the possibility that certain identity threats may be as important as prejudice in determining the outcomes of interracial interactions.

Signaling threat: how situational cues affect women in math, science, and engineering settings.

This study examined the cues hypothesis, which holds that situational cues, such as a setting's features and organization, can make potential targets vulnerable to social identity threat. Objective and subjective measures of identity threat were collected from male and female math, science, and engineering (MSE) majors who watched an MSE conference video depicting either an unbalanced ratio of men to women or a balanced ratio. Women who viewed the unbalanced video exhibited more cognitive and physiological vigilance, and reported a lower sense of belonging and less desire to participate in the conference, than did women who viewed the gender-balanced video. Men were unaffected by this situational cue. The implications for understanding vulnerability to social identity threat, particularly among women in MSE settings, are discussed.

Clearing the air: identity safety moderates the effects of stereotype threat on women's leadership aspirations.

Exposing participants to gender-stereotypic TV commercials designed to elicit the female stereotype, the present research explored whether vulnerability to stereotype threat could persuade women to avoid leadership roles in favor of nonthreatening subordinate roles. Study 1 confirmed that exposure to the stereotypic commercials undermined women's aspirations on a subsequent leadership task. Study 2 established that varying the identity safety of the leadership task moderated whether activation of the female stereotype mediated the effect of the commercials on women's aspirations. Creating an identity-safe environment eliminated vulnerability to stereotype threat despite exposure to threatening situational cues that primed stigmatized social identities and their corresponding stereotypes.