The model proposed by Whitehouse comprises two stages: (1) phenotypic matching or experiencing of an opaque, emotionally salient event, resulting in an individual's becoming fused with a group, and (2) motivation of self-sacrificial behavior by this group identity fusion (GIF), particularly when the group is under threat, because the individual conceptualizes the group as deserving of self-sacrifice. Relying on a large body of both theoretical and empirical literature, this model provides a reasonable framework for predicting when individuals come to engage in self-sacrifice. However, among those who are highly fused with their group, this model does less in addressing who is particularly likely to engage in self-sacrifice, which is a key question of theoretical and practical importance.

Although past work has noted there are no obvious or consistent demographic variables that reliably predict who is willing to engage in terrorism (Atran Reference Atran2003; Reference Atran, Webel and Arnaldi2011; Weatherston & Moran Reference Weatherston and Moran2003), save being male (Möller-Leimkühler Reference Möller-Leimkühler2018), there likely are psychological risk factors. Therefore, we argue that incorporating one or more individual difference frameworks from the psychological literature into Whitehouse's model will help predict who is most likely to self-sacrifice.

There are a number of relevant individual difference constructs, which may provide insight. For example, in empathy models, those who experience the suffering of victims to a greater degree may be more willing to sacrifice themselves to harm an oppressive group or body (Batson et al. Reference Batson, Kennedy, Nord, Stocks, Fleming, Marzette, Lisher, Hayes, Kolchinsky and Zerger2007; Moskalenko & McCauley Reference Moskalenko and McCauley2011). According to attachment theory, individuals who crave a sense of acceptance and community are motivated to engage in violent, costly acts to feel accepted and valued within their group (Cassidy & Shaver Reference Cassidy and Shaver2010). And in theories related to aggression and honor, individuals who are more concerned with their reputation and inclined toward violence are more sensitive to slights against their group's honor and more likely to respond with violence to signal group dedication (Möller-Leimkühler Reference Möller-Leimkühler2018).

Here, we focus on the central individual difference framework from the dual-process cognition literature, “cognitive style” – the extent to which individuals rely on reflective deliberation versus intuitive gut instincts in their decision making (Evans & Frankish Reference Evans and Frankish2009; Evans & Stanovich Reference Evans and Stanovich2013; Frederick Reference Frederick2005; Kahneman Reference Kahneman2011; Pennycook et al. Reference Pennycook, Fugelsang and Koehler2015b; Rand et al. Reference Rand, Tomlin, Bear, Ludvig and Cohen2017; Sloman Reference Sloman1996). Mapping this individual difference onto Whitehouse's model, we argue that people with a more intuitive cognitive style will be (1) more affected by an initially salient, negative experience – although through a less deliberative pathway than the one emphasized by Whitehouse – and (2) more likely to choose a costly pro-social act of self-sacrifice once identity-fused to the group.

The first stage of Whitehouse's model is heavily reliant on conscious, deliberative processes (memory, reflecting on causation, etc.). Based on this perspective, deliberative people (those more inclined to reflect on experience) should show a stronger link from the salient negative experience to GIF. However, we propose that there are other, less deliberative pathways through which negative and highly emotional experiences can increase GIF. For example, uncertainty identity (Hogg Reference Hogg2007), misattribution of arousal (White et al. Reference White, Fishbein and Rutsein1981), and cognitive dissonance theories (Festinger Reference Festinger1957), to name just a few, could all explain how undergoing a negative experience increases GIF through more intuitive, less deliberative processes. Further, work on the function of deliberation suggests that it is more likely to result in self-serving decision making relative to decisions guided by intuition (Bear & Rand Reference Bear and Rand2016; Rand Reference Rand2016), which seems likely to impede GIF. Finally, group leaders may sometimes intentionally highlight salient, emotional events in an effort to lead others to experience GIF (and, thus, be more likely to fight and die for the cause), and intuitive individuals are likely to be more susceptible to these messages as they are more credulous across a variety of domains (Pennycook & Rand Reference Pennycook and Rand2018; Pennycook et al. Reference Pennycook, Cheyne, Barr, Koehler and Fugelsang2015a; Swami et al. Reference Swami, Voracek, Stieger, Tran and Furnham2014). For these various reasons, individuals who rely on intuition may be more likely to become highly fused in response to a negative emotional event.

The second half of the model argues that when those with high GIF are confronted with a threat to their group, they are more likely to respond by engaging in violent self-sacrifice. Incorporating the cognitive style framework, we argue that among those with high GIF, more intuitive individuals are more likely to engage in costly self-sacrifice for at least two reasons.

The first involves ideological belief (most notably religious belief), which has been linked to intuitive processing (Pennycook et al. Reference Pennycook, Ross, Koehler and Fugelsang2016; Shenhav et al. Reference Shenhav, Rand and Greene2012; Yilmaz et al. Reference Yilmaz, Karadöller and Sofuoglu2016). Here, we would expect more intuitive people to more fully (wholeheartedly) embrace religious narratives, including those that endorse martyrdom, life after death, and other cultural belief narratives that mitigate the perceived costs of self-sacrificial acts. More deliberative people, in contrast, may be more skeptical of, and more likely to critique, these specific narratives of the faith.

Second, we would expect more intuitive people to engage in more heuristic-based reasoning, which (in the appropriate circumstances) has also been linked to costly acts of cooperative behavior (Everett et al. Reference Everett, Ingbretsen, Cushman and Cikara2017; Rand Reference Rand2016; Rand et al. Reference Rand, Greene and Nowak2012). Contingent on membership in a close-knit, cooperative community (as one with high GIF and psychological kinship is expected to be), more intuitive individuals would be more likely to engage in costly cooperative behavior, including self-sacrifice (Rand & Epstein Reference Rand and Epstein2014).

In sum, we argue that the addition of individual difference frameworks, such as cognitive style, would improve the predictive power of Whitehouse's model, as well as provide insight into the type of messaging that may help prevent acts of self-sacrifice.