Expectations of Social Inclusion and Exclusion

Individuals engage in social interactions generally expecting inclusion (Kerr and Levine, 2008; Wesselmann et al., 2010, 2013). This expectation seems reasonable, given individuals’ basic need to establish and maintain social connections to sustain physical and psychological well-being (Baumeister and Leary, 1995). However, individuals often experience social exclusion; situations broadly involving someone being disengaged or separated from others physically or emotionally (Riva and Eck, 2016). Exclusion experiences include various phenomena, such as interpersonal rejection, ostracism, and various types of discrimination (Smart Richman and Leary, 2009; Wesselmann et al., 2016). These diverse threats to social inclusion are so detrimental, researchers argue that humans likely developed mechanisms safeguarding social inclusion (Lieberman, 2013), facilitating quick detection of threats to inclusionary status (Pickett and Gardner, 2005; Kerr and Levine, 2008; Wesselmann et al., 2012b). When threats occur, individuals experience cognitive and behavioral changes to facilitate recovery (Smart Richman and Leary, 2009; Williams, 2009). Considerable research has examined individuals’ responses to exclusion, but less has focused on how expectations of inclusion or exclusion moderate those responses. In this article, we highlight research focused on how individuals calibrate their expectations of social inclusion and exclusion, and how these expectations influence the effect of exclusion on individuals’ feelings of relational value and other adverse effects of social exclusion.

Individuals engage in social interactions generally expecting inclusion (Kerr and Levine, 2008;Wesselmann et al., 2010Wesselmann et al., , 2013. This expectation seems reasonable, given individuals' basic need to establish and maintain social connections to sustain physical and psychological well-being (Baumeister and Leary, 1995). However, individuals often experience social exclusion; situations broadly involving someone being disengaged or separated from others physically or emotionally (Riva and Eck, 2016). Exclusion experiences include various phenomena, such as interpersonal rejection, ostracism, and various types of discrimination (Smart Richman and Leary, 2009;Wesselmann et al., 2016).
These diverse threats to social inclusion are so detrimental, researchers argue that humans likely developed mechanisms safeguarding social inclusion (Lieberman, 2013), facilitating quick detection of threats to inclusionary status (Pickett and Gardner, 2005;Kerr and Levine, 2008;Wesselmann et al., 2012b). When threats occur, individuals experience cognitive and behavioral changes to facilitate recovery (Smart Richman and Leary, 2009;Williams, 2009). Considerable research has examined individuals' responses to exclusion, but less has focused on how expectations of inclusion or exclusion moderate those responses. In this article, we highlight research focused on how individuals calibrate their expectations of social inclusion and exclusion, and how these expectations influence the effect of exclusion on individuals' feelings of relational value and other adverse effects of social exclusion.

PERCEIVING EXCLUSIONARY CUES
Individuals monitor their environment for exclusionary cues using their sociometer, which detects fluctuations in an individual's relational evaluation (Leary, 1999;Leary and Baumeister, 2000). Relational evaluation is operationalized as "the degree to which others regard their relationship with the individual as valuable, important, or close" (Leary, 1999, p. 33). Individuals' perceived relational value is a proxy for inclusionary status (Leary, 1999;Leary and Baumeister, 2000). Exclusionary cues vary from direct to subtle (e.g., language, facial expression, non-verbal behaviors; Kerr and Levine, 2008), yet all produce feelings of social pain (Williams, 2009). Such exclusionary cues may be unambiguously clear, such as a partner stating they do not want to work with you (Maner et al., 2007), not being included during a game (Williams et al., 2000), or being treated in a cold and aloof manner (Geller et al., 1974;Wesselmann et al., 2010). Conversely, exclusion can occur in various subtle ways, such as not receiving eye contact from an avatar, which causes feelings of exclusion (Böckler et al., 2014) and lowered implicit self-esteem (Wirth et al., 2010). Even being stared through by a passerby (as if one does not exist) causes feelings of social disconnection (Wesselmann et al., 2012a).
Conversation dynamics can provide cues to one's inclusionary status (Koudenburg, 2014). Smooth conversations indicate relationship solidarity, while uncomfortable pauses are threatening to social connectedness (Koudenburg et al., 2011(Koudenburg et al., , 2013. Exclusion can occur during conversations when group members switch to a language unfamiliar to the target (Hitlan et al., 2006;Dotan-Eliaz et al., 2009), when others use unknown acronyms (Hales et al., in press), through exclusive laughter (Klages and Wirth, 2014), or when the conversation makes people feel "out-of-the-loop"-when a person is included in the group, but feels excluded due to knowing there is information that they lack (Jones et al., 2009(Jones et al., , 2011.

WHEN EXPECTATIONS OF INCLUSION ARE VIOLATED
During exclusion, relational devaluation occurs, and individuals suffer aversive physical and psychological consequences (Williams, 2009). However, little work has examined how expectations of inclusion/exclusion affect exclusion's consequences. Does expecting exclusion temper the negative outcomes, and unexpected exclusion intensify them, perhaps by threatening individuals' confidence in their sociometers? Because individuals monitor their environments for inclusion-relevant social cues (Leary, 1999;Williams, 2009), they likely experience unexpected exclusion more extremely than excepted exclusion. For example, Wesselmann et al. (2010) found that although excluded individuals aggressed more than included individuals, individuals who experienced unexpected exclusion demonstrated the most aggression and showed the least confidence in their sociometer. Further, Wirth et al. (2017) found participants who were unexpectedly excluded experienced increased basic need threat and negative affect, as well as decreased confidence in their sociometer, compared to participants who expected their exclusion. The latter group experienced need threat and negative affect once they received exclusionary social cues, and these negative effects continued on after they were ultimately excluded. Additionally, individuals who expected exclusion did not indicate decreased confidence in their sociometer between the time they received exclusionary cues and when they were excluded. Finally, Rudert and Greifeneder (2016) explicitly manipulated participants' expectations of situational norms and found that excluded participants experienced less negative effects when perceiving exclusion (rather than inclusion) as the norm. Collectively, these studies support neuroscience research suggesting that exclusion-related pain partially involves expectation violations (Somerville et al., 2006).
Based on previous theory (Leary, 1990;Wesselmann et al., 2016), relational evaluation is a key mechanism in understanding the degree to which social exclusion causes negative psychological outcomes. Specifically, deflated relational evaluation can cause negative feelings (Leary et al., 2001;Buckley et al., 2004) and may be related to lowered fulfillment of psychological needs, implicit self-esteem, and aggressive behavior temptations (Wirth et al., 2010;Bernstein et al., 2013). In response, individuals engage in behaviors aimed at safeguarding their relational evaluation. Socially excluded individuals have enhanced memory for social information (Gardner et al., 2000), increased desire to make new friends, and preferences for new potential interaction partners (Maner et al., 2007). Further, excluded individuals show increased attention to genuine signals of social inclusion (Bernstein et al., 2008(Bernstein et al., , 2010a and emotional expressions of happiness vs. anger (Sacco et al., 2011). Excluded individuals may be guided perceptually and behaviorally toward sources of social inclusion (i.e., increased attunement to positive, inclusive targets; DeWall et al., 2009). To our knowledge, no studies have directly assessed whether relational evaluation mediates excluded participants' perceptual and behavioral biases toward re-inclusion, but some evidence suggests participants' threatened need for belonging can mediate these effects (Bernstein et al., 2010a).

Social Cue Attention and Response as Adaptation
Research on cognitive responses to exclusion are mixed: some studies show cognitive depletion (Baumeister et al., 2002), whereas others show cognitive benefits such as increased attention to and memory for social information (e.g., Gardner et al., 2000;Pickett et al., 2004;Bernstein et al., 2008). This apparent contradiction may be due to the paradigm used to examine the effects; paradigms revealing deficits tend to involve non-social tasks, while paradigms involving social tasks typically reveal benefits post-exclusion. Perhaps excluded individuals allocate available cognitive resources to tasks most effective to restoring relational evaluation levels, which non-social tasks may not do (Shilling and Brown, 2016).
To our knowledge, research has not directly tested this strategic re-distribution hypothesis (but see Gardner et al., 2000 comparing social and non-social memory). Such studies would strengthen the theoretical argument that individuals respond to exclusion in adaptive ways (i.e., survival-enhancing: Wesselmann et al., 2012b). Additionally, research should investigate if and how expectation violations influence any strategic re-distribution patterns. Williams (2009) argues that once individuals experience the immediate negative effects of exclusion, they subsequently focus cognitive resources on interpreting the situation to assess methods of recovery. These efforts may involve attributional processes or behavioral strategies. If individuals unexpectedly experience decreased relational evaluation, they may show strategic re-distribution more intensely than excluded individuals who expected exclusion because they experienced a more intense threat. Alternatively, simply experiencing any exclusion may trigger a strategic re-distribution response that is broad and undifferentiated to maximize re-inclusion efforts (Pickett and Gardner, 2005), and expectations may have little (or no) influence pattern.
Future research should examine if and how expectations matter for chronically excluded individuals. Williams (2009) refers to these individuals as being in the resignation stage, and argues that they likely come to expect exclusion in daily interactions. These individuals may experience learned helplessness that effectively comes from being unable to avoid exclusion or alter its consequences. Even though resigned individuals may anticipate exclusion, they may find unexpected exclusionary episodes (either in daily life or in a laboratory setting) more painful than other individuals precisely because they are caught unaware. Alternatively, resigned individuals may simply be numb to the negative effects of exclusion regardless of their momentary expectations (Bernstein and Claypool, 2012;Riva et al., 2014).The resignation stage of exclusion is relatively new and research is sparse (but see , so we can merely speculate on the influence of expectations in this context.

Paradigm Constraints, Expectation Cues, and Responses
Exclusion paradigms often blindside participants with exclusion (Williams and Wesselmann, 2011), but many exclusion experiences outside the laboratory likely involve some warning (Spoor and Williams, 2007;Kerr and Levine, 2008) or clear attributional information relevant during reflection (Nezlek et al., 2012). Thus, the conclusions drawn from most exclusion research may be limited in how well the research represents these everyday exclusion experiences. We have already discussed how Wirth et al. (2017) showed that the social cues prior to exclusion can affect individuals' expectations of, and ultimately responses to, their exclusion. Tuscherer et al. (2016) examined an additional understudied factor, participants' perceptions of fairness for an exclusion experience, and found that participants who perceived their exclusion as unfair experienced greater threat to efficacy needs (i.e., control and meaningful existence) than participants who perceived their exclusion as fair. These studies suggest that researchers should be mindful of how these two factors may relate to their future research questions and design their paradigms accordingly. Researchers should also consider how social cues and perceptions of fairness may influence each other both within a single exclusion episode and across subsequent episodes.
Participants' expectations of inclusion also likely influence whether participants will choose to respond pro-or anti-socially to exclusion, as well as the degree of their response, which is a current paradox in the literature (Wesselmann et al., 2015). Some research demonstrates that excluded participants will only respond pro-socially when they perceive the opportunity for reaffiliation (Maner et al., 2007;Mead et al., 2011). Potentially, any exclusion paradigm could be adapted to influence participants' expectations by manipulating explicit situational norms (Rudert and Greifeneder, 2016), confederate social cues in face-to-face or virtual get-acquainted paradigms (Wesselmann et al., 2010;Wirth et al., 2017), or explicit instructions involving opportunities to meet the target of participants' pro-/anti-social behavior (Maner et al., 2007). Researcher could also use the life alone paradigm (Twenge et al., 2001), which provides participants with fake feedback about their future social lives (e.g., their future will be lonely), as an expectations manipulation and then examine how those expectations influence the effects of subsequent exclusion using in vivo paradigms.

Further Integrating Relational Evaluation into Research
Researchers should investigate the specific role that relational evaluation plays in the consequences of exclusion, and how situation-level and individual-level characteristics influence this construct. Situational factors that may influence expectations of relational evaluation could be the psychological closeness of the sources of inclusion (e.g., a romantic partner; Arriaga et al., 2014), exclusion by in-group vs. out-group members (e.g., Gonsalkorale and Williams, 2007;Bernstein et al., 2010b;Goodwin et al., 2010;Cursan et al., 2016), or situations that require some type of exclusion (i.e., role-based exclusion, Nezlek et al., 2012;Rudert and Greifeneder, 2016); although exclusion in each case may hurt, violations of one's expected relational evaluation may help explain if and when exclusion may hurt more (or less) initially, and may also explain differential recovery (e.g., Wirth and Williams, 2009). Individual factors may also influence one's expected relational evaluation levels. For example, narcissistic individuals may expect high relational evaluation and thus respond with more aggression than non-narcissists when their expectations are violated (Bushman and Baumeister, 1998;Twenge and Campbell, 2003). Additionally, individuals high in rejection sensitivity (Downey and Feldman, 1996) may have lower expectations for perceived relational evaluation because they presume social interactions will not likely be positive. However, rejection-sensitive individuals expect exclusion in social situations, yet they respond with more hostility to exclusion than less-sensitive individuals (Ayduk et al., 2008;Pfundmair et al., 2015), suggesting accurate expectations may not always offer advantages. Regardless, individuals' expectations of inclusion, and the subsequent effects on relational evaluation, should be considered in future theorizing and research on the effects of social exclusion.

AUTHOR CONTRIBUTIONS
EW, JW, and MB each contributed to the theoretical arguments in this article.