Decoding “us” and “them”: Neural representations of generalized group concepts.

Abstract

Humans form social coalitions in every society on earth, yet we know very little about how the general concepts us and them are represented in the brain. Evolutionary psychologists have argued that the human capacity for group affiliation is a byproduct of adaptations that evolved for tracking coalitions in general. These theories suggest that humans possess a common neural code for the concepts in-group and out-group, regardless of the category by which group boundaries are instantiated. The authors used multivoxel pattern analysis to identify the neural substrates of generalized group concept representations. They trained a classifier to encode how people represented the most basic instantiation of a specific social group (i.e., arbitrary teams created in the lab with no history of interaction or associated stereotypes) and tested how well the neural data decoded membership along an objectively orthogonal, real-world category (i.e., political parties). The dorsal anterior cingulate cortex/middle cingulate cortex and anterior insula were associated with representing groups across multiple social categories. Restricting the analyses to these regions in a separate sample of participants performing an explicit categorization task, the authors replicated cross-categorization classification in anterior insula. Classification accuracy across categories was driven predominantly by the correct categorization of in-group targets, consistent with theories indicating in-group preference is more central than out-group derogation to group perception and cognition. These findings highlight the extent to which social group concepts rely on domain-general circuitry associated with encoding stimuli's functional significance. (PsycINFO Database Record

The Partisan Brain: An Identity-Based Model of Political Belief

“…According to the theory, people can define themselves according to who they are as individuals as well as their membership in various social groups (defining themselves as a woman, parent, professor, Democrat, or American). Likewise, evolutionary theory has argued that the brain evolved to detect coalitional alliances [17] and neuroimaging research has found that the human brain represents political affiliations, such as Republican or Democrat, similarly to other forms of social identity [18,19]. However, the relevance of any given social identity varies with social context.…”

Mere membership

“…While the MGP is widely known, its consequences are broader than generally recognized, making it paradoxically both familiar and underappreciated. Indeed, a central goal of this review is to detail some fundamental challenges these effects pose to common accounts of the origins of ingroup bias [25][26][27].…”

“…Cognitively, ingroup bias in both real and minimal groups can be described as a form of cognitive consistency or "balance" between group identification and self-esteem, such that manipulations of any one "leg" of this cognitiveaffective triangle affect the other two [30,31]. And neuroscientifically, recent work has identified distinct brain signatures of intergroup categorization [26,32]. In one such study, individuals were placed into minimal groups and a classifier was trained on patterns of brain activation from the incidental observation of minimal ingroup and outgroup targets; that classifier was than tested on brain activation in response to political ingroup and outgroup targets, and was able to identify group membership along this orthogonal dimension with high accuracy [26].…”

“…And neuroscientifically, recent work has identified distinct brain signatures of intergroup categorization [26,32]. In one such study, individuals were placed into minimal groups and a classifier was trained on patterns of brain activation from the incidental observation of minimal ingroup and outgroup targets; that classifier was than tested on brain activation in response to political ingroup and outgroup targets, and was able to identify group membership along this orthogonal dimension with high accuracy [26]. Thus, at multiple levels of analysis, from individual phenomena through more general aspects of cognitive and neural structure, minimal groups seem capable of explaining many aspects of intergroup functioning.…”

Decoding the neural representation of self and person knowledge with multivariate pattern analysis and data‐driven approaches

“…Thus far, much of this prior work has focused on detecting a social target's race or group membership based on facial characteristics; however, a pair of recent studies (Cikara, Van Bavel, Ingbretsen, & Lau, ; Lau & Cikara, ) has examined how broader social groups based not on faces but on shared group affiliations (e.g., political preferences, assignment to teams) are represented in the brain. In both of these studies, a minimal groups approach (Tajfel, Billig, Bundy, & Flament, ) was used to assign a group of 23 self‐identified democrat participants to one of two arbitrary teams (i.e., eagles or rattlers) in order to generate the feeling of group affiliation without the baggage of stereotypes associated with real‐world social groups.…”