Neural processing of social exclusion in individuals with psychopathic traits: Links to anger and aggression

Highlights

• We measured a neural index of elaborative processing during a Cyberball task.

• Psychopathic traits were related to greater elaborative processing of ambiguous exclusion.

• Psychopathic traits were related to less elaborative processing of social inclusion.

• Elaborative processing interacted with psychopathic traits to predict anger and aggression.

• Aberrant processing of exclusion may drive aggression in those with psychopathic traits.

Abstract

Psychopathy is a cluster of personality traits associated with high rates of aggression. While research on psychopathic traits largely focuses on neurobiological factors implicated in aggression, other research suggests that contextual factors, such as social exclusion, also contribute to promoting aggression. Yet, the relationships among psychopathic traits, neural processing of exclusion, and aggression remain unknown. A sample of 76 adolescents and young adults completed Cyberball, a task involving conditions of social inclusion, ambiguous exclusion, and unambiguous exclusion. During Cyberball, a slow wave (SW) event-related potential (an index of elaborative processing) and self-reported anger were measured. Additionally, acts of real-world aggression were assessed. Results indicated that as psychopathic traits increased, SW during ambiguous exclusion also increased, but SW during inclusion decreased. However, the combination of smaller SW during ambiguous exclusion and higher psychopathic traits predicted heightened anger following Cyberball and more frequent real-world aggression. This response to social exclusion among individuals with elevated psychopathic traits may represent an unreflective, reactive style that exacerbates anger and aggression in certain contexts. These data suggest that neurobiological dysfunction in elaborative processing is related to psychopathic traits, and social context comprises another important influence on the aggression of individuals with elevated psychopathic traits.

Introduction

Aggression is hostile, unfriendly behavior that often results in physical, social, and/or emotional harm. Aggressive acts entail not only tangible costs (e.g., financial; Corso et al., 2007, Waters et al., 2005), but also intangible costs (e.g., psychological; McCollister et al., 2010). A host of factors (e.g., personality traits, environmental conditions, neural dysfunction, genetics) are known to influence risk for engaging in aggression. One factor reliably linked to higher rates and severity of aggression is psychopathy (Hare and McPherson, 1984, Kruh et al., 2005, Murrie et al., 2004, Salekin et al., 1996, Serin and Amos, 1995), a disorder characterized by a set of traits including callousness, manipulativeness, and impulsivity. Longitudinal research shows that elevated psychopathic traits in adolescence predict aggression and violent crime in adulthood (Gretton et al., 2004). Therefore, psychopathy represents a key risk factor in the development and persistence of aggressive behavior. Although there is substantial evidence that individuals with elevated psychopathic traits are more aggressive, research is lacking regarding the contexts in which they behave aggressively.

Social exclusion, sometimes referred to as ostracism or peer rejection, is a particularly powerful context that can lead to negative affect, hostility, anger, and aggression (Lansford et al., 2010, Williams, 2001, Leary et al., 2006). In a series of longitudinal studies, Dodge et al. (2003) reported that for both boys and girls social exclusion by peers around age 6 was a strong predictor of aggressive behavior around age 8, particularly for those who were already above the median on aggression at age 6. Consistent with this finding, studies focused on adolescence show that social rejection can lead to negative affect (Sebastian et al., 2010) and aggression (Reijntjes et al., 2011). The experience of social exclusion unleashes a cascade of negative consequences that span cognitive (Buelow et al., 2015), emotional, and behavioral domains (e.g., self-regulation; Baumeister et al., 2005, Chester and DeWall, 2014; risky behavior; Peake et al., 2013, Svetieva et al., 2016). Unsurprisingly, exclusion also affects interpersonal functioning, such that individuals who have been excluded are less likely to engage in prosocial behavior (Twenge et al., 2007, Will et al., 2016, Moor et al., 2012) and are more likely to attribute hostile intent to others (DeWall et al., 2009a, Reijntjes et al., 2011). Thus, exclusion may heighten risk for aggression through multiple psychosocial avenues.

Social exclusion also impacts neurobiological processes, with evidence for altered perceptual and attentional processing of social cues following exclusion (Chester et al., 2014, Kawamoto et al., 2014, DeWall et al., 2009b). In a laboratory-induced form of social exclusion (i.e., the Cyberball task), the slow-wave (SW) event-related potential (ERP) is a widely studied and validated measure of cognitive-affective processing of this social context (Crowley et al., 2009, Crowley et al., 2010, White et al., 2012, Sreekrishnan et al., 2014, Baddam et al., 2016). Broadly, the SW, which is maximal at centroparietal sites and is evident from as early as 300 ms following stimulus presentation, indexes the extent to which individuals engage in elaborative processing, particularly of intrinsically motivating stimuli (Cuthbert et al., 2000, Hajcak et al., 2010, Ruchkin et al., 1992, Schupp et al., 2004). More specifically, in the Cyberball task, enhanced SW is related to experiences of heightened threat to basic needs (e.g., control, self-esteem) following exclusion (Crowley et al., 2010, Sreekrishnan et al., 2014). The SW responses to both unambiguous, clear slights (being continuously excluded by peers) and ambiguous slights (being subtly excluded in the context of overall inclusion) track cognitive-affective reactions to Cyberball (Crowley et al., 2010, Crowley et al., 2009). However, only a small number of studies examined how neural processing during exclusion relates to aggression (e.g., Chester et al., 2014, Eisenberger et al., 2007), and no studies used ERP for this purpose, despite the advantageousness of ERP for measuring how individuals process rapidly unfolding social interactions.

Moreover, no research has examined neural processing of social exclusion as it relates to psychopathic traits. There is some evidence that children with elevated psychopathic traits are at higher risk for experiencing exclusion in the first place (Waller et al., 2017) and that social exclusion mediates the relationship between psychopathic traits and later affiliation with antisocial peers (Kimonis et al., 2004). However, it is unclear if individuals with elevated psychopathic traits process the experience of exclusion differently from individuals with lower levels of these traits, and whether these potential variations in information processing are associated with engagement in real-world aggression. Exploring the relationships among psychopathic traits, neural processing of social exclusion, and aggression is especially important, as it is precisely the way in which psychopathic individuals process information that is implicated in their deviant behavior (Baskin-Sommers and Newman, 2012, Brennan et al., 2017, Blair, 2010).

To examine the relationships among psychopathic traits, social exclusion, and emotional-behavioral outcomes, we used a Cyberball social exclusion task paired with dense-array electroencephalography (EEG) in an at-risk sample of adolescents and young adults. The goals of the study were three-fold. First, we were interested in the relationship between psychopathic traits and neural responses to social exclusion, specifically the SW ERP. Based on research suggesting that neural responses to ambiguous and unambiguous social exclusion index overlapping yet separable cognitive-affective reactions to the Cyberball task (Crowley et al., 2009, van Noordt et al., 2015), we examined responses to both types of exclusion events. Second, the feeling of anger is a key aspect of the exclusion-aggression link (Chow et al., 2008, Zimmer-Gembeck et al., 2016); however, since not all individuals experience exclusion in the same way, we were interested in assessing for whom this relationship was strongest. Specifically, we examined whether the relationship between SW and anger following the Cyberball task varied depending on level of psychopathic traits. Finally, given the association between exclusion and aggression (Lansford et al., 2010, Leary et al., 2006), we also examined whether psychopathic traits moderated the relationship between SW and real-world aggression. Delineating the relationship between psychopathic traits and responses to social exclusion is crucial for shedding light on whether aberrant processing of social contexts underlies the aggression that renders psychopathy so impairing and destructive.