Neural and Behavioral Effects of Being Excluded by the Targets of a Witnessed Social Exclusion
Year: 2015

The consequences of social exclusion can be extremely detrimental to physical and emotional well being, ranging from mild distress to extreme violence and aggression. Research findings indicate that witnessing exclusion is just as common as experiencing exclusion and can invoke similar levels of distress. As such, it is also important to examine responses and reactions to the targets after witnessing it. Accordingly, this study examined the association between witnessing and experiencing social exclusion and event related brain potential (ERP) activity. ERPs were collected while participants played a game of Cyberball with the previous targets of a witnessed inclusion or exclusion and were either included or excluded themselves. Results showed increased N2 and decreased P3b to exclusionary throws regardless of the overall context of the social interaction and regardless of the context of the witnessed interaction. Additionally, participants who were excluded reported lower needs fulfillment and mood than those who were included providing support for the Need Threat model of social exclusion. Further, results showed increased P3b amplitude to inclusionary events after witnessing exclusion. This lends support to the Social Monitoring System suggesting that witnessed exclusion attunes individuals' attention to social cues in the environment that would increase inclusionary status.  The silent treatment, a cold shoulder, a disapproving or dirty look: all of these are forms of social exclusion, or the act of being ignored, rejected, or isolated (Williams, 2007) Social exclusion is so common that most individuals will both engage in it and suffer the consequences of it (Williams, Cheung, Choi, 2000; Williams, 2001) It is not unique to humans or American culture. In fact, social exclusion has been documented across time, cultures, and social species. It is prevalent among all age groups and in every level of society from institutions and small groups to interpersonal dyadic relationships (Williams et al. 2000; Williams, 2001) Social exclusion serves as a form of social control, punishing deviance and strengthening in group cohesiveness (Williams, 2001) Much of human behavior is motivated by a desire to belong to a group and this is suggested to have stemmed from the early evolution of humans. Specifically, those ostracized from the group were less likely to survive because of the loss of protection and reproductive opportunities. However, members of the excluding group experience increased cohesiveness therefore increasing security and reproductive chances (Williams, 2007) As such, those skilled at detecting exclusion were the most likely to survive and flourish. It is theorized that humans developed an ostracism detection system that signals an alarm directing one's attention to determining the extent of exclusion and allocating resources to cope with it (Williams, 2007) Pain is thought to be the signal that captures the person's attention, and research has shown that physical and social pain share an overlapping neural and computational basis (Eisenberger Lieberman, 2004) Exclusion even in the smallest form, by a computer, strangers, or even by despised outgroup members, has been shown to be physically and psychologically distressing (Zadro,  Williams, Richardson, 2004; Gonsalkorale Williams, 2007; Williams, 2007) The consequences of social exclusion may range from mild distress to extreme violence and aggression seen in school shootings, and often include negative emotional experiences such as depression, anxiety, loneliness and feelings of isolation (Twenge, Baumeister, Tice, Stucke, 2001, Leary, Kowalski, Smith, Phillips, 2003; Masten, Telzer, Eisenberger, 2011) Given the frequency of social exclusion, most have used it, been targeted by it, or have observed it happening to others. In fact, witnessing social exclusion is just as common as experiencing it and may lead to feelings of distress similar to that felt when experiencing it (Masten et al. 2013) The ostracism detection system is theorized to aid in selfand otherdetection and lead individuals to feel the pain of others' as their own (Wesselmann, Bagg, Williams, 2009) As such, it is important to examine how witnessing exclusion may affect an individual's reactions to his or her own subsequent social experiences. Additionally, given that individuals may be sensitive to the exclusion of others, their own responses may be modified when they interact with the people that they just observed being excluded. Feeling the pain of these previously excluded individuals may impact how these individuals process their own social exclusion. Therefore, the goal of the proposed study is to examine the neural and behavioral effects of being excluded by the targets of a witnessed social exclusion. The hope was that this study would shed light on how the social experience of witnessing exclusion and then interacting with the individuals who were just excluded influences individuals' reactions to their own social experiences. This review will begin with the theoretical models of social exclusion. These models offer insight into the effects of social exclusion, responses to it, and mediators of exclusionRunning  5 related effects. A discussion of the literature on the neural and behavioral effects of witnessing social exclusion will follow in order to provide a basis possible effects witnessing exclusion will have on participants. Neuroimaging research revealing the neural correlates of social exclusion and how these neural indices relate to the processes of perceiving and responding to social exclusion will then be discussed followed by a discussion of event related potentials and their advantages over neuroimaging research. The review will conclude with a description of the current study. Models of Social Exclusion Need Threat Model. Proposed in 1997 by Williams and subsequently revised in 2001, the Need Threat Model of social exclusion states that social exclusion threatens the fundamental human needs of belonging, self esteem, control, and meaningful existence. These four needs are important for human motivation and survival and as such, individuals experience physical, emotional and social pain when they are threatened. Each one is unique and important and, according to Williams (2001) even short term exposure to exclusion can immediately trigger a threat to these needs. The need to belong has been suggested to be the most fundamental of all human needs (Baumeister Leary, 1995) Indeed, much of human behavior is motivated by a need to form and maintain social bonds to feel a desired sense of belonging. A lack of strong, stable interpersonal relationships is detrimental to one's physical and mental health. Social exclusion serves as a threat to belonging more than any other unpleasant social response because it removes all feelings of connectedness. Even a strained sense of connectedness like that experienced in an argument is better than none at all (Zadro et al. 2004) Social exclusion also poses a threat to an individual's self esteem because it often occurs without explanation, leaving the individual to notice that they were excluded and devise their Running Head: WITNESSING AND EXPERIENCING SOCIAL EXCLUSION 6 own reasoning for it (Williams, 2001) More than likely, the individual will attribute the reasons for exclusion to internal characteristics or something they did wrong. Actively ruminating on internal reasons for exclusion serves to threaten one's self esteem and leads to feelings of inadequacy (Williams, 2001) Feelings of control are also threatened when one is excluded because the target no longer has control over interactions with the source because there is no opportunity for any kind of responsive exchange (Williams, 2001) Without feelings of control, an individual may develop learned helplessness and subsequently become depressed (Seligman, 1975 as cited in Williams, 2001) The last need that is threatened by social exclusion is the need for a sense of meaningful existence (Williams Zadro, 2005) Social exclusion serves as a lens to what life would be like if the target did not exist and as such acts as a mortality salience cue threatening the individual's sense of importance (Williams Zadro, 2005) According to the Need Threat model, there is a temporal progression of reactions to social exclusion. Immediate reactions to social exclusion include hurt feelings, anger, lowered self esteem, negative mood, and physiological arousal (Williams, 2001) In the short term, the individual attempts to reduce these negative reactions and regain the needs threatened by social exclusion. Thus, an individual may try to form new social bonds, make assertions of selfimportance, and exert control over others or some other aspect of the situation (Williams, 2001; Williams Zadro, 2005) Continual exposure to exclusion thwarts an individual's attempts to regain threatened needs and the ability to recover becomes increasingly difficult. Thus, long term exposure to social exclusion may lead to feelings of helplessness, worthlessness and despair, and isolation (Williams, 2001) Although there is considerable evidence that immediate reactions to even minor instances of social exclusion are quick, powerful and invariant, short term and long term reactions are Running Head: WITNESSING AND EXPERIENCING SOCIAL EXCLUSION 7 dependent on several dimensions including visibility, motive, quantity, and causal clarity as well as various mediators and moderators such as situational and individual differences as well as internal or external attributions of responsibility for the exclusion (Wil