Human sociality is frequently conceptualized through deliberate affiliations, such as families, political organizations, professional teams, and voluntary associations. Yet, a substantial portion of human collective interaction originates not from premeditated design or mutual personal attraction, but through the arbitrary convergence of situational forces, spatial co-presence, and unexpected external stimuli. Understanding how random aggregations of unrelated individuals rapidly coalesce into functioning, psychologically interdependent units remains a foundational pursuit within sociology and social psychology.
Accidental Group
1. Concise Definition
An accidental group is a transient social collective formed involuntarily and spontaneously due to shared physical proximity, arbitrary circumstance, or an unforeseen external event, rather than premeditated intention, formal organizational mandate, or established interpersonal bonds. While initially functioning as a mere statistical aggregate of strangers, an accidental group acquires psychological reality and varying degrees of group cohesion when external events demand coordination, foster mutual awareness, or impose an interdependence of fate.
Unlike intentional or purposive groups, the accidental group does not depend on shared ideological values, reciprocal prior knowledge, or institutional scaffolding for its emergence. Instead, it arises dynamically at the threshold where passive spatial co-presence transforms into active social interdependence. Such collectives frequently emerge during mechanical failures, environmental crises, localized accidents, or sudden spatial confinement, demonstrating the inherent plasticity of human social behavior under abrupt situational shifts.
Over the course of its existence, an accidental group may either dissolve back into unrelated individuals once the circumstantial catalyst subsides, or evolve into an organized, enduring group if structural norms, sustained roles, and collective identities crystallize during the shared experience.
2. Etymology & Linguistic Origin
The term accidental group unites two distinct lexical lineages derived from Latin and Romance linguistic roots. The adjective accidental traces to the Latin verb accidere, compounded from the prefix ad- (meaning “to” or “toward”) and cadere (meaning “to fall”). In Late Latin, the participial noun accidens denoted a chance happening, an unexpected event, or a non-essential attribute of a subject—a philosophical distinction popularized by Aristotelian scholasticism to differentiate essential properties from contingent occurrences. The word entered Middle English via Old French in the fourteenth century, retaining its connotation of that which occurs by chance or contingency rather than by intrinsic design.
The noun group is comparatively younger in the English lexicon, originating in the late seventeenth century from the French groupe, which was borrowed from the Italian gruppo or groppo. Originally a technical term in fine arts describing a cluster of sculpted or painted figures composed harmoniously together, the word is suspected to have Germanic roots (cognate with the West Germanic *kruppaz*, denoting a round mass, knot, or lump). By the eighteenth and nineteenth centuries, social philosophers adapted the term to designate any assemblage of interacting persons.
The synthesis of both terms into accidental group occurred in early twentieth-century social science literature. Early sociologists and crowd psychologists employed the phrase to classify circumstantial aggregations—distinguishing incidental gatherings of citizens from deliberate political bodies, established religious fellowships, and kinship networks.
3. Pronunciation & Grammatical Form
The term is pronounced phonetically in Standard American English as /æk.sɪˈdɛn.təl ɡruːp/ and in British English (Received Pronunciation) as /ˌæk.sɪˈden.tl̩ ɡruːp/. Grammatically, accidental group operates as a compound open noun phrase consisting of the descriptive adjective “accidental” modifying the countable common noun “group.”
Its standard pluralization is accidental groups. Derived and related morphological forms include the nominalized construct accidental grouping, which places greater semantic emphasis on the ongoing, emergent process of collective assembly rather than on the static social entity itself. In empirical contexts, researchers may also employ the adjectival phrasing accidentally formed group to indicate the operational methodology or circumstance governing collective boundary generation.
4. Detailed Conceptual Explanation
To fully grasp the nature of an accidental group, one must examine the theoretical distinction between a social aggregate and a true social group. In standard sociological frameworks, an aggregate consists of individuals who share physical space at a given moment—such as shoppers scattered across a transit terminal or passengers sitting silently across an airport concourse—without interacting or perceiving themselves as a unified entity. These individuals possess what social psychologists describe as minimal entitativity, a construct denoting the degree to which an assemblage of persons is perceived as a coherent, unified social whole.
An accidental group occupies a dynamic liminal space between an aggregate and a mature group. The defining characteristic of an accidental group is the sudden introduction of a shared contingency that shatters psychological detachment. When an elevator stalls between floors, a subway carriage loses electrical power, or a flash flood cuts off a roadway, the previously disconnected individuals are abruptly bound together. This sudden environmental disruption creates what Kurt Lewin identified as an “interdependence of fate”: the well-being, survival, or comfort of each individual becomes inextricably linked with the immediate state and actions of the collective.
Once mutual awareness is activated, psychological boundaries form with remarkable speed. The individuals inside the stranded elevator instantly categorize themselves as “us” (the confined party) in contrast to “them” (the rescue personnel or external bystanders). Within this newly established boundary, internal social roles begin to crystallize spontaneously. Leaders may emerge to manage anxiety or ration resources; liaisons establish contact with external support; and emotional caretakers offer reassurance to distressed individuals. This rapid self-organization occurs in the complete absence of pre-existing organizational charts or contractual relationships.
Moreover, the lifespan of an accidental group is inherently bound to its precipitating condition. Most accidental groups are hyper-ephemeral: once the elevator doors open, the flood waters recede, or the delayed flight reaches its destination, the interdependence of fate dissipates, and the group typically dissolves back into atomized social aggregates. However, if the shared circumstantial event involved severe psychological trauma, protracted collective struggle, or heroic collaboration, the accidental group can transcend its situational origins, developing enduring social rituals, shared collective memories, and permanent social organizations.
5. Historical Development
The scholarly conceptualization of accidental groups emerged alongside the development of modern crowd psychology, urban sociology, and group dynamics during the late nineteenth and twentieth centuries. The initial intellectual impetus arose from the rapid urbanization of industrializing societies, where human beings were routinely forced into close physical proximity with complete strangers.
Early crowd theorists, most notably Gustave Le Bon in his influential 1895 treatise The Crowd: A Study of the Popular Mind, observed how accidental assemblies of urbanites could abruptly exhibit unified psychological properties. Le Bon argued that incidental assemblies could generate a “collective soul,” though his perspective was colored by a profound skepticism regarding crowd rationality, pathologizing spontaneous gatherings as susceptible to contagion, emotional regression, and intellectual degradation.
During the early twentieth century, American sociological pioneers offered more nuanced structural taxonomies. Charles Horton Cooley (1909) articulated the distinction between primary groups (intimate, enduring associations such as families) and secondary groups (goal-oriented, formal associations). Although accidental groups did not neatly match either category, Cooley’s framework inspired researchers to investigate intermediate forms of human association that emerged without deliberate intent.
The middle of the twentieth century marked a fundamental theoretical transition from speculative crowd psychology to empirical social psychology. Kurt Lewin, establishing the Research Center for Group Dynamics at MIT in the 1940s, introduced Field Theory. Lewin demonstrated that group cohesion was not contingent upon long-standing historical affinity or personal similarity, but on active dynamic interdependence. This theoretical shift allowed researchers to understand how sudden situational forces could rapidly transform a collection of strangers into a functionally coherent accidental group.
In the 1960s and 1970s, sociological interest converged around disaster research and collective behavior. Scholars such as Ralph Turner and Lewis Killian formulated Emergent Norm Theory, directly refuting Le Bon’s contagion thesis. Turner and Killian demonstrated that when crisis scenarios disrupt conventional institutional order, accidental groups do not devolve into irrational chaos. Instead, they rapidly generate novel, context-specific normative standards that guide member behavior. Concurrently, disaster sociologists like E. L. Quarantelli and Russell Dynes cataloged the systematic emergence of spontaneous search-and-rescue groups following earthquakes, explosions, and transport collapses, firmly embedding the accidental group within mainstream sociological theory.
6. Theoretical Foundations
The operational mechanics of accidental groups are illuminated by several prominent theoretical frameworks within the behavioral sciences. Each framework explains a distinct phase of the group’s lifecycle, from initial emergence to functional coordination.
Lewin’s Field Theory and Interdependence: Field theory posits that human behavior is determined by the total psychological field or “life space” of the individual, which encompasses both the person and their immediate environment. Kurt Lewin argued that the fundamental criterion for group existence is dynamic interdependence—specifically, the interdependence of fate and the interdependence of goals. In an accidental group, individuals who previously possessed distinct, unrelated life spaces suddenly experience a violent convergence of their environmental fields. When a catastrophic or unexpected event occurs, individual outcomes become interdependent. Lewinian theory explains why strangers cooperate instantly: their individual survival and equilibrium require collective equilibrium.
Emergent Norm Theory: Developed by Ralph Turner and Lewis Killian, this framework explains how order is maintained within unscripted gatherings. In an unexpected situational crisis, institutionalized routines are frequently rendered useless. According to this theory, participants in an accidental group do not behave identically out of primitive emotional contagion. Rather, through subtle verbal and nonverbal cues, key individuals begin performing actions that appear sensible under the circumstances. These actions are observed, evaluated, and socially validated by others, leading to the rapid emergence of informal behavioral norms. The accidental group thus governs itself through improvised social consensus.
Social Identity and Self-Categorization Theories: Formulated by Henri Tajfel and John Turner, Self-Categorization Theory elucidates the psychological shift that occurs during accidental group formation. Individuals maintain multiple levels of self-representation, ranging from personal identity (“I”) to social identity (“we”). In mundane circumstances, individuals co-present in public spaces operate predominantly at the personal identity level. However, when an external catalyst exposes a common salience or shared vulnerability, cognitive depersonalization occurs: individuals recategorize themselves as members of a distinct in-group. This cognitive realignment fosters mutual trust, facilitates cooperative altruism, and aligns actions toward collective coping strategies.
Complex Adaptive Systems Theory: From a contemporary systems perspective, accidental groups can be modeled as self-organizing complex adaptive systems. Free agents interacting via local rules without centralized leadership spontaneously generate macroscopic organizational structures in response to environmental disturbances. Information cascades, spontaneous role allocation, and rapid feedback loops characterize the transition of an accidental aggregate into an adaptive functional network.
7. Key Components, Types & Dimensions
Accidental groups can be deconstructed into essential structural components, behavioral dimensions, and operational taxonomies that distinguish them across different contexts.
- Spatial-Temporal Co-presence: The non-negotiable physical or localized proximity of individuals at a singular, shared point in space and time.
- Exogenous Catalyst: An unexpected external event, systemic failure, environmental hazard, or logistical interruption that disrupts baseline activity and demands collective attention.
- Perceived Common Fate: The cognitive and affective recognition among participants that their personal outcomes, well-being, or path forward are mutually dependent upon the situation and each other.
- Absence of Prior Interpersonal Design: The lack of a premeditated plan, shared historical objective, or pre-existing institutional recruitment binding the members together before the event.
- Spontaneous Role Differentiation: The rapid emergence of operational roles—such as task directors, technical problem-solvers, emotional stabilizers, and external communicators—without formal appointments.
- Permeability and Transience: Highly fluid structural boundaries that expand or contract based on environmental developments, generally characterized by an ephemeral lifespan.
Social theorists broadly classify accidental groups into three distinct structural subtypes based on their situational function and operational intensity:
- Passive Circumstantial Aggregates: Collectives brought together by minor inconveniences or administrative delays (e.g., travelers stranded at an airport departure gate overnight). Interdependence is low, and interaction is dominated by informal commiseration and shared information-gathering rather than acute survival behavior.
- Crisis-Emergent Action Collectives: Highly functional groups that crystallize instantaneously around extreme life-or-death emergencies (e.g., passengers working collaboratively to escape a capsized ferry). These groups exhibit high entitativity, intensive self-sacrifice, and immediate functional division of labor.
- Confined-Space Cohorts: Groups formed by unexpected environmental encapsulation (e.g., individuals trapped in an underground mine, stalled elevator, or collapsed building). These collectives prioritize long-term resource conservation, psychological stabilization, and structured internal communication over prolonged periods.
8. Examples & Illustrative Cases
Empirical history offers numerous striking examples illustrating the formation, operation, and dissolution of accidental groups in everyday life and historical crises.
A classic, low-stakes archetype is the stalled elevator cohort. Eight unrelated office workers enter an elevator cab in a metropolitan skyscraper, intentionally avoiding eye contact and maintaining interpersonal distance. Suddenly, the cables seize, the lights flicker, and the cab halts between the 40th and 41st floors. The social dynamic shifts immediately: silent strangers begin conversing, assessing air vents, testing emergency communication buttons, and comforting panicked occupants. Within five minutes, an accidental group has emerged with identifiable task leaders, reassurance givers, and a shared social identity. Once building technicians open the doors an hour later, the individuals trade brief pleasantries and return to their private lives, dissolving the group entirely.
A profound historical example occurred during the evacuation of Lower Manhattan by water on September 11, 2001. When the terrorist attacks severed subway connections, bridges, and tunnels, over half a million civilians were trapped along the seawalls of Manhattan. Spontaneously, an accidental collective of hundreds of civilian tugboat operators, ferry crews, private yacht owners, and stranded commuters formed what became the largest water evacuation in history—larger even than the evacuation of Dunkirk. Unrelated vessel captains organized ad-hoc staging zones, communication protocols, and boarding priorities via radio and hand gestures, rescuing over 500,000 people in under nine hours without prior centralized planning.
Another illustrative instance is found in spontaneous search-and-rescue squads formed in the immediate aftermath of major urban earthquakes, such as the 1985 Mexico City earthquake or the 2010 Port-au-Prince disaster in Haiti. Long before municipal or international emergency units arrived, nearby citizens assembled into informal tactical squads. Strangers formed bucket brigades, crawled into debris voids, and carried the injured to medical clinics. These accidental collectives exhibited extraordinary internal coordination, demonstrating how shared exposure to extreme danger transforms disparate individuals into unified, high-performing crisis response units.
9. Measurement & Assessment
Quantifying, observing, and assessing accidental groups presents distinct methodological challenges due to their spontaneous, unpredictable, and often hazardous nature. Sociologists and social psychologists utilize several specialized empirical techniques to capture their dynamics.
Entitativity Measurement Scales: Researchers evaluate the degree to which an accidental group is perceived by its members and outside observers as a real social entity using validated entitativity scales, such as those refined by Brian Lickel and colleagues (2000). Participants rate the collective on Likert scales measuring dimensions such as common goals, shared outcomes, level of interaction, structural organization, and psychological permeability.
Sociometric Network Mapping: In post-incident investigations, researchers use sociometric surveys to chart the rapid formation of communication and command links within accidental groups. Network centrality metrics (identifying which individuals emerged as central hubs of communication, advice, or emotional reassurance) reveal how flat, unstructured crowds organize organically into structured networks.
High-Fidelity Virtual Reality (VR) Simulation: Because staging real emergencies raises severe ethical and logistical barriers, contemporary experimental researchers employ immersive VR environments. Experimental subjects are placed in virtual building fires, subway evacuations, or aircraft malfunctions alongside computer-controlled avatars or other human participants. Tracking physical movements, communication frequencies, altruistic interventions, and reaction latencies allows researchers to rigorously assess emergent role allocation and collaborative decision-making under controlled, repeatable conditions.
Post-Disaster Archival and Qualitative Coding: Disaster researchers heavily utilize qualitative content analysis, coding audio transcripts of emergency 911 dispatch calls, black box cockpit recordings, social media geolocation data, and post-crisis interviews. Through grounded theory methodologies, analysts trace the minute-by-minute evolution of situational language—tracking the linguistic shift from the singular pronoun “I” to the plural “we” as a direct proxy for the cognitive crystallization of the accidental group.
10. Applications & Practical Significance
The study of accidental groups extends far beyond abstract social theory; it has profound, direct implications for urban design, emergency management, organizational safety, and public policy.
In emergency management and civil defense, outdated operational models treated crowds as passive, panicky masses that required strict authoritarian control. Modern disaster research demonstrates that accidental groups are almost invariably rational, altruistic, and capable of first-line crisis management. Contemporary disaster preparedness protocols now emphasize emergent multi-agency coordination, designing systems that empower rather than suppress accidental collectives. Emergency systems are engineered to provide clear, actionable information directly to affected groups, enabling them to self-organize search, rescue, and triage operations effectively prior to the arrival of professional first responders.
In aviation and public transportation safety, understanding accidental group dynamics governs how crew members are trained to manage emergencies. Cabin crew undergo specialized training to identify and mobilize spontaneous leaders within accidental passenger cohorts. Flight attendant manuals include scripts specifically designed to activate collective accountability—directing specific passengers to open emergency exits, catch evacuees at the bottom of slides, or guide lines away from smoke—leveraging the natural propensity of accidental groups to adopt functional social roles under pressure.
In architectural and urban design, civil engineers leverage knowledge of accidental group formation to build safer environments. Designing stairwells, emergency exits, and public transit terminals requires an understanding of how human flow transitions from individual movement to dense collective movement during bottlenecks. Recognizing that accidental groups act collectively rather than as atomized individuals informs the placement of spatial wayfinding markers, wide convergence zones, and decentralized escape paths that facilitate collective navigation.
11. Research & Empirical Evidence
A rich corpus of empirical investigations has examined the cognitive, structural, and behavioral underpinnings of accidental groups across a variety of social disciplines.
In their seminal taxonomy of groups, Brian Lickel and colleagues (2000) conducted extensive multi-method investigations into intuitive human perceptions of group types. In their research, published in the Journal of Personality and Social Psychology, the authors had participants categorize and evaluate broad arrays of human gatherings. The results confirmed that individuals distinguish four robust intuitive group taxonomies: intimacy groups, task groups, loose associations, and transitory/accidental groups (such as people at a bus stop or stranded passengers). The study revealed that although accidental groups are rated lower in interaction duration and past history, their entitativity surges dramatically whenever common fate and dynamic interaction are introduced.
Crucial empirical insights were provided by John Drury and colleagues (2009) in their field research on survivors of real-world disasters, including the July 7, 2005 London bombings and crowd stampedes. Drury’s team tested the Social Identity Model of Collective Resilience. Their empirical data demonstrated that shared environmental threat directly transformed accidental aggregates into cohesive social identity units. Rather than degenerating into selfish, stampeding behavior, survivors consistently exhibited high levels of mutual aid, queuing patience, and self-sacrifice. The researchers demonstrated that the perception of shared vulnerability created an emergent social identity, which directly drove coordinated, prosocial survival behaviors.
Another foundational area of research stems from Bibb Latané and John Darley’s (1968) studies on bystander intervention. Latané and Darley demonstrated that within passive accidental groups, diffusion of responsibility and pluralistic ignorance frequently inhibit individual action during emergencies when the situation remains ambiguous. However, follow-up experiments demonstrated that once the ambiguity of the crisis is broken, or when members of the accidental group interact directly or share a verbal bond, the collective flips rapidly from passive hesitation into a coordinated intervention force. This confirms that communication density is a vital moderating variable in accidental group activation.
12. Cultural & Cross-Cultural Considerations
The formation speed, structural cohesion, and internal norms of accidental groups vary considerably across different socio-cultural settings. Cross-cultural psychology highlights how broad societal orientations influence spontaneous collective behavior.
In collectivistic societies (such as Japan, South Korea, or communal agrarian societies in Sub-Saharan Africa), individuals are socialized from early childhood to maintain high baseline attentiveness to group welfare, relational harmony, and collective responsibility. Consequently, when an accidental group forms during a public disturbance or transport failure in these cultures, the transition from passive co-presence to active, orderly cooperation is often seamless. Norms of social order, deference to age or perceived competence, and public self-restraint emerge rapidly, minimizing chaotic expressions of personal distress.
In contrast, in highly individualistic cultures (such as the United States, the United Kingdom, or Australia), accidental gatherings typically retain personal boundary defenses for longer durations. Initial reactions to situational disturbances may center around individual rights, personal preservation, and personal spatial autonomy. However, research indicates that once a catastrophic threshold is crossed, individualistic norms can rapidly yield to intensive prosocial altruism, frequently manifesting in charismatic, self-nominated leadership and improvisational operational squads.
Furthermore, cultural variations along the dimension of tightness versus looseness, as conceptualized by Michele Gelfand, exert a strong influence on accidental group behavior. “Tight” cultures possess strong social norms and low tolerance for deviant behavior, leading accidental groups to mirror formal institutional hierarchies even in spontaneous crisis settings. In “loose” cultures, where behavioral norms are more permissive and flexible, accidental groups rely heavily on unconventional, improvisational problem-solving mechanisms, exhibiting greater tolerance for experimental role-taking and unstructured action.
13. Criticisms, Debates & Limitations
Despite the recognized utility of the concept, the theoretical framing of accidental groups has sparked notable debates and theoretical critiques within sociology and social psychology.
The Ontological Validity Debate: A primary theoretical criticism raised by purist social structuralists questions whether an “accidental group” is a legitimate group at all, or simply a mislabeled social aggregate. Skeptics argue that defining any circumstantial collection of strangers as a group dilutes the conceptual value of group dynamics. They assert that genuine groups require ongoing relational continuity, enduring social norms, stable role matrices, and a distinct social structure that outlasts any single physical situation. From this perspective, calling a ten-minute elevator gathering a “group” overextends psychological nomenclature.
Methodological and Observational Bias: Another limitation concerns empirical methodology. Because accidental groups form unpredictably, field researchers are rarely on-site during their genesis. Consequently, much of the empirical literature relies on retrospective self-reports, post-disaster qualitative interviews, or simulated laboratory proxies. Retrospective interviews are susceptible to survival bias, memory distortion, and post-hoc narrative rationalization—wherein participants retroactively impose heroic, orderly organizational structure onto what may have been a fundamentally chaotic, disorganized event.
The Rationality versus Panic Controversy: A longstanding tension persists between older crowd contagion theories and modern emergent resilience models. While contemporary researchers often emphasize emergent altruism, critics caution against romanticizing accidental collectives. Under specific conditions—such as extreme perceptual panic, severe exit blockages, or complete sensory deprivation—accidental aggregations can indeed fail to achieve cooperative integration, resulting in fatal crush mechanics, social paralysis, or dysfunctional behavioral fragmentation.
14. Related Terms & Distinctions
To ensure conceptual precision, the accidental group must be clearly differentiated from related sociometric and psychological classifications:
- Social Aggregate: A collection of individuals who happen to be in the same place at the same time but lack physical interaction, shared identity, or mutual interdependence (e.g., pedestrians walking down a sidewalk). Distinction: An accidental group develops interdependence of fate and emergent internal coordination, which an aggregate lacks.
- Deliberate / Formed Group: A group intentionally established to achieve an explicit, pre-planned objective, such as a corporate board, a military unit, or an academic committee. Distinction: Deliberate groups are formed through conscious intent and institutional recruitment, whereas accidental groups are generated entirely by unforeseen circumstances.
- Primary Group: A small, enduring social group characterized by intimate, personal, face-to-face relationships that play a central role in identity formation (e.g., families, close childhood friend circles). Distinction: Accidental groups are transient, formed among strangers, and lack long-term emotional intimacy.
- Secondary Group: A formal, impersonal group bound together by contractual, institutional, or professional relationships (e.g., a labor union or professional association). Distinction: Secondary groups possess formal charters, legal mechanisms, and codified rules, whereas accidental groups rely on emergent, unwritten norms.
- Crowd / Mob: A large, often dense gathering of individuals that can display high emotional arousal, shared attention, or collective contagion. Distinction: Mobs frequently act with emotional contagion or destructive collective impulses, whereas accidental groups typically form around functional problem-solving, situational coping, and mutual assistance.
15. Summary / Key Takeaways
The accidental group serves as a powerful testament to the adaptive, flexible nature of human social organization. When unexpected events disrupt everyday routines, strangers bound only by physical co-presence can rapidly transform into coordinated social systems. Driven by an emergent interdependence of fate, dynamic cognitive self-categorization, and spontaneous norm generation, these transient collectives organize internal roles, execute complex collaborative tasks, and maintain prosocial stability in the absence of pre-existing organizational structures. Recognizing the mechanisms that govern accidental groups deepens our scientific understanding of human sociality and informs critical practical operations in disaster management, architectural safety, and civil defense.
References
- Cooley, C. H. (1909). Social organization: A study of the larger mind. Charles Scribner’s Sons.
- Drury, J., Cocking, C., & Reicher, S. (2009). The nature of the collective: The primary role of social identity in collective resilience. Journal of Personality and Social Psychology, 97(5), 903–925. https://doi.org/10.1037/a0016335
- Latané, B., & Darley, J. M. (1968). Group inhibition of bystander intervention in emergencies. Journal of Personality and Social Psychology, 10(3), 215–221. https://doi.org/10.1037/h0026570
- Lewin, K. (1948). Resolving social conflicts: Selected papers on group dynamics. Harper & Brothers.
- Lickel, B., Hamilton, D. L., Wieczorkowska, G., Lewis, A., Sherman, S. J., & Uhles, A. N. (2000). Varieties of groups and the perception of group entitativity. Journal of Personality and Social Psychology, 78(2), 223–246. https://doi.org/10.1037/0022-3514.78.2.223
- Turner, R. H., & Killian, L. M. (1987). Collective behavior (3rd ed.). Prentice-Hall.