Mass Behavior

Abstract

Mass behavior is a type of social behavior: the collective conduct of people acting together as a crowd, a mass, or a public, from a panicked evacuation to a protest march to a fashion craze. Cognitive and social psychology ask how individual minds produce coordinated collective action, and whether a crowd strips away the self or expresses a shared one. This article develops the field's main threads: the classical crowd psychology of Le Bon; the collective behavior theories of Turner and Killian and of Smelser; deindividuation and its reinterpretation by the social identity model; the social identity approach to crowds and mass emergencies, which recasts panic as rare and mutual aid as the rule; and threshold models of how collective action cascades. A worked example and three interactive demonstrations make the mechanisms manipulable.

Keywords: mass behavior, crowd psychology, collective behavior

A football stadium empties in orderly lines after a bomb threat; a rumour of petrol shortage empties the pumps in an afternoon; a peaceful demonstration turns, in one quarter of a crowd and not the rest, into a confrontation with police. Each is behavior that belongs to no single person—it exists only in the aggregate—and each has struck observers as evidence that people in crowds act differently from people alone. The question that has organised the field for over a century is how differently, and why (Reicher, 2001).

The behavioural sciences approach mass behavior through several distinct questions. Does the crowd dissolve the rational individual into a suggestible “group mind,” as the first crowd psychologists claimed? If anonymity changes conduct, does it release a universal impulse or shift people toward a particular standard? Where does the apparent order or disorder of a crowd come from—the situation, the composition, or a shared sense of who “we” are? And when disaster strikes a mass of strangers, do they trample one another or help? The sections below take these in turn, after first placing mass behavior within the broader category of social behavior under which it is classified.

What Mass Behavior Is

Mass behavior, in the sense the behavioural sciences study it, is the relatively spontaneous and unstructured conduct of a large number of people responding to a common stimulus or situation—what the Medical Subject Headings vocabulary places among forms of social behavior as the behavior of people in crowds, masses, and publics. It is the umbrella term for a family of phenomena: the crowd (people physically co-present, from a queue to a riot), the mass (dispersed people responding to the same event, such as a stock-market panic or a run on a product), and diffuse collective episodes such as rumour, fashion, craze, and moral panic. What unites them is that the behavior is a property of the collective, not reducible to the sum of individual intentions decided in advance (Turner & Killian, 1987).

Two distinctions organise the field. The first separates the collective behavior tradition in sociology—concerned with how such episodes emerge, spread, and subside—from crowd psychology proper, concerned with the mental processes of the individual in the crowd. The second, and more consequential, separates accounts on which the crowd subtracts something from the person (reason, self-awareness, moral restraint) from accounts on which it supplies something (a shared social identity that makes coordinated action possible). Much of the history below is the story of the field moving from the first kind of account to the second (Reicher, 2001).

In the Medical Subject Headings vocabulary, Mass Behavior is a descriptor filed under Social Behavior, and the placement is apt: mass behavior is the limiting case of social behavior, interpersonal conduct scaled up to the collective, where the actors are often strangers and the relevant unit is the group rather than the dyad. The remainder of this article takes the field's major perspectives in turn, from the classical crowd psychology that opened it to the social identity approach that now dominates it.

Perspectives on Mass Behavior

The study of mass behavior is organised less by one grand theory than by a succession of perspectives, each reacting to the last. Classical crowd psychology treated the crowd as a primitive group mind. The sociological collective behavior tradition replaced that with emergent norms and value-added sequences. Deindividuation research brought the question into the laboratory as a loss of self, and the social identity tradition then overturned the loss-of-self account, recasting the crowd as the expression of a shared identity—an account that now anchors the study of crowds, policing, and mass emergencies. A separate, formal tradition models collective action as a threshold cascade. Table 1 summarises them, and the sections that follow develop each in turn.

Table 1

Perspectives on Mass Behavior

Classical Crowd Psychology

The scientific study of crowds opens with Gustave Le Bon, whose 1895 book The Crowd gave the field its founding image and its founding error. Le Bon argued that an individual absorbed into a crowd undergoes a transformation: a collective “mental unity” takes hold—a group mind—in which conscious personality dissolves, reason gives way to emotion and instinct, and ideas spread from person to person by contagion as if by hypnotic suggestion. The crowd, on this account, is impulsive, credulous, and intellectually inferior to its members taken singly, a “psychological crowd” capable of both atrocity and heroism but never of deliberation (Le Bon, 1896).

The influence of this picture far outran its evidence. Its enduring appeal lies in capturing something real—that people in crowds do act in concert and do things they would not do alone—while explaining it with a mechanism, the submergence of the rational self, that later work would reject. Two features of the account proved especially durable and especially misleading: the idea that the crowd is defined by the loss of individual identity, and the idea that its behavior is essentially mindless. Nearly every subsequent perspective can be read as a response to Le Bon—either refining the mechanism of submergence or denying that submergence is what happens at all (Reicher, 2001).

Collective Behavior: Emergent Norms and Value-Added

American sociology recast the problem without the group mind. Ralph Turner and Lewis Killian advanced emergent norm theory: a crowd is not uniform and is not governed by contagion, but develops, in the course of an ambiguous situation, a norm—a shared definition of what is happening and how one ought to act—that appears to justify the crowd's behavior and pressures members to conform or at least not to dissent. What looks like unanimity is often the silencing of dissent by a vocal few whose conduct defines the emergent norm; the crowd only seems of one mind (Turner & Killian, 1987).

Neil Smelser offered a more architectural account. His value-added theory held that an episode of collective behavior requires a sequence of determinants that accumulate like stages in a manufacturing process, each necessary and each narrowing what can follow: structural conduciveness (conditions that make the behavior possible), structural strain (tension or deprivation), the spread of a generalised belief, a precipitating factor, the mobilisation of participants for action, and the operation (or failure) of social control. No single factor produces the crowd; the behavior emerges only when the full value-added chain is present (Smelser, 1962). Both theories were advances on Le Bon in treating crowd behavior as meaningful and situated—but both still located the crowd's conduct in the situation rather than in any positive social identity the members might share.

Deindividuation

Experimental social psychology took up Le Bon's submergence idea and tried to operationalise it as deindividuation: a psychological state, induced by anonymity and immersion in a group, in which self-observation and concern for social evaluation are reduced, weakening the normal internal restraints on behavior. Leon Festinger and colleagues coined the term, proposing that in a group people are not seen as individuals, which lowers inner restraints and frees behavior that would otherwise be inhibited (Festinger et al., 1952). The best-known demonstration was Edward Diener's field study of Halloween trick-or-treaters, which found that children were more likely to steal extra candy when they were anonymous and in a group than when alone and identifiable—apparently confirming that anonymity releases transgression (Diener et al., 1976).

Yet when Tom Postmes and Russell Spears meta-analysed the whole deindividuation literature, the classical prediction failed. Across the studies, anonymity and group immersion did not reliably increase antinormative or antisocial behavior; what deindividuating conditions actually did was increase conformity to situation-specific norms—sometimes antisocial, but just as often prosocial, depending on the setting (Postmes & Spears, 1998). This result motivated a reinterpretation. The SIDE model—the Social Identity model of Deindividuation Effects, developed by Stephen Reicher, Russell Spears, and Tom Postmes—argued that anonymity in a group does not abolish the self but shifts it: by submerging personal identity and personal differences, anonymity makes a shared social identity more salient, so people conform more to the norms of the group that is salient in the situation, not less to norms in general (Reicher et al., 1995). Deindividuation, on this reading, is not a loss of identity but a change in which identity governs behavior—the point the second demonstration makes concrete. Demo 1 lets the reader vary anonymity and the salient group norm and watch antinormative behavior rise or fall accordingly.

The Social Identity Approach to Crowds

The decisive break came from Stephen Reicher's analysis of a real crowd event. Studying the 1980 St Pauls “riot” in Bristol, Reicher showed that the crowd's behavior was neither mindless nor unlimited: the crowd attacked symbols of the state and of outside commercial exploitation—police, banks—but left homes, local shops, and bystanders untouched, and its action was confined to the St Pauls neighbourhood. The pattern made sense only if the crowd was acting from a shared social identity as members of a community, whose norms defined both legitimate targets and legitimate limits. Far from losing identity, the crowd members had shifted to a collective one that patterned their conduct (Reicher, 1984).

This grew into the elaborated social identity model (ESIM) of crowd behavior, which adds a crucial intergroup dimension: crowd events are typically encounters between two groups—say, demonstrators and police—each acting on its own understanding of the situation. When police treat an entire crowd as dangerous and impose indiscriminate force, they can change how crowd members see themselves: people who came with varied aims come to share a sense of common, illegitimate treatment, unite around an oppositional identity, and support confrontation they would earlier have rejected. Conflict, on this account, is often an emergent product of the intergroup dynamic rather than the expression of a pre-existing mob (Reicher, 2001). John Drury and Reicher extended the model to show that acting on a shared identity, and prevailing, can be empowering—a source of collective psychological empowerment and positive emotion that sustains participation and can outlast the event itself through what they term collective psychological empowerment (Drury & Reicher, 2009). Frank Neville and Reicher documented the experiential side of this: shared identity in a crowd brings a felt sense of relatedness and intensified, shared emotion (Neville & Reicher, 2011).

The approach has had its sharpest practical payoff in the policing of crowds. Clifford Stott's research on football crowds and public order showed that policing built on the old group-mind assumption—treating a whole crowd as a latent mob and meeting it with indiscriminate force—tends to create the very disorder it fears, whereas a graded, identity-sensitive approach that facilitates lawful crowd aims and differentiates the few from the many keeps the peace (Stott et al., 2012). Alexander Templeton and colleagues added the behavioural signature of a psychological crowd: people who share an identity literally move together, coordinating their walking in ways a mere aggregate of strangers does not (Templeton et al., 2018). Demo 2 lets the reader see how indiscriminate versus differentiated policing shifts a crowd's shared identity and the proportion willing to confront.

Mass Emergencies and Collective Resilience

The image of the panicking mob—a crowd reduced by fear to a selfish stampede—is the emergency-services counterpart of Le Bon's group mind, and it has fared no better under scrutiny. Anthony Mawson argued that the “mass panic” model misreads human responses to threat and disaster: flight is typically oriented toward the familiar—toward attachment figures and known others—rather than being a blind, antisocial scramble, and affiliation, not panic, is the dominant response (Mawson, 2005). The empirical record of real disasters bears this out: trampling and selfish flight are the exception, and mutual help among strangers is the rule.

John Drury and colleagues gave this a social identity explanation and a name: collective resilience. In a comparative study of survivors of emergencies and disasters—including the 2005 London bombings—they found that a sense of common fate in the emergency transforms a mere physical crowd of strangers into a psychological group with a shared identity, and that this emergent shared identity is what motivates the orderly, mutually supportive, often self-sacrificing behavior that survivors actually report (Drury et al., 2009). Drury's integrative review consolidated the evidence that shared social identity is the mechanism converting a crowd from a source of danger into a source of support in emergencies (Drury, 2018), and translated it into concrete guidance for emergency planners, who are advised to treat the public as a resource and to build rather than override the crowd's own solidarity (Drury et al., 2019). Evangelos Ntontis and colleagues followed the solidarity after the emergency, tracing how the emergent groups that form during a disaster endure or decline in the months of recovery that follow—and what sustains them (Ntontis et al., 2020). The same framework was brought to bear on the COVID-19 pandemic, where Reicher and Stott argued that public adherence and “order” depend on shared identity and trust rather than on an assumed fragility or selfishness of the public (Reicher & Stott, 2020). Demo 3 lets the reader vary the degree of shared identity in an evacuating crowd and read off how mutual helping rises as selfish flight falls.

Threshold Models of Collective Action

A quite different tradition asks a formal question: given that individuals differ in how readily they will join a collective action, when does a crowd tip from a few actors into a mass? Mark Granovetter's threshold model supplies the sharpest answer. Each person has a threshold—the proportion of others who must already be acting before that person will join—and the crowd's outcome is a cascade determined by the distribution of thresholds, not by the average radicalism of its members. A crowd composed entirely of people with moderate average thresholds may do nothing if there is no instigator with a low enough threshold to start the chain; a crowd with the same average but one more instigator may riot completely (Granovetter, 1978).

The model's enduring lesson is that collective behavior cannot be read off the dispositions of individuals. Two crowds with nearly identical members can produce opposite outcomes because of a single person's threshold at the margin, and an observer who infers from a riot that the rioters were uniformly radical—or from quiescence that they were uniformly moderate—commits a basic error. Threshold models thereby formalise what emergent norm theory and the social identity approach assert qualitatively: that the crowd is a system, and its behavior is a property of the interaction among its members, not a simple aggregate of what each brought to it. The third mechanism—cascade from a threshold distribution—is the subject of the worked example below.

Worked Example

The mechanisms become concrete in three small exercises, each matching one of the demonstrations. The numbers below are illustrative—they capture the qualitative shape of the published findings rather than reproducing any single reported statistic.

Deindividuation as a shift, not a loss (SIDE). Model the probability of antinormative behavior as a function of two inputs: anonymity a (from 0 to 1) and the salient group norm n, coded +1 when the salient norm is aggressive and −1 when it is prosocial. The classical deindividuation prediction is P = a: anonymity alone releases transgression. The SIDE prediction instead makes anonymity amplify the salient norm: P = 0.5 + 0.4 × a × n. Set full anonymity, a = 1. Under an aggressive salient norm (n = +1), P = 0.5 + 0.4×1×1 = 90%. Under a prosocial salient norm (n = −1), the same deindividuating condition gives P = 0.5 + 0.4×1×(−1) = 10%. Identical anonymity, opposite behavior: the point is that anonymity does not release a universal antisocial impulse but shifts conduct toward whichever identity is salient (Postmes & Spears, 1998). Demo 1 lets the reader move a and flip n and read off P.

Policing and the escalation of conflict (ESIM). Represent the proportion of a crowd willing to confront police as a function of shared oppositional identity s (0 to 1), with confrontation C = 0.1 + 0.8 × s. Suppose a crowd begins fragmented, with low shared identity s = 0.2, so C = 0.1 + 0.8×0.2 = 26%. Indiscriminate force—treating the whole crowd as a mob—unites it around a shared sense of illegitimate treatment, raising s to 0.8: now C = 0.1 + 0.8×0.8 = 74%. The crowd did not arrive a mob; the policing made it one by changing who the members took themselves to be (Stott et al., 2012). A differentiated approach that leaves s low keeps confrontation near its floor. Demo 2 lets the reader apply either policing style and watch s and C move.

Collective resilience in a mass emergency. Model the fraction of people who help strangers during an evacuation as a function of shared social identity s (0 to 1): helping H = 0.2 + 0.6 × s, with selfish flight the complement 1 − H. In a mere physical crowd with no shared identity (s = 0), H = 0.2 + 0.6×0 = 20% help and 80% flee for themselves—the mass-panic image. But let a common threat forge a shared identity (s = 1): H = 0.2 + 0.6×1 = 80% help and only 20% flee selfishly. The same crowd, facing the same danger, behaves in opposite ways depending on whether a shared identity has emerged—which is why disaster research finds mutual aid, not stampede, to be the norm (Drury et al., 2009). Demo 3 lets the reader vary s and trace helping against selfish flight.

Discussion

Read across its perspectives, the science of mass behavior tells a single long story: the slow replacement of a subtraction account of the crowd with a social identity account. Le Bon's crowd was defined by what it took away—reason, self-awareness, restraint—leaving a primitive group mind governed by contagion (Le Bon, 1896). The sociological tradition stripped out the group mind but still explained the crowd by its situation: an emergent norm that defines the moment, or a value-added chain of structural conditions (Turner & Killian, 1987; Smelser, 1962). Deindividuation research carried the submergence idea into the laboratory, only for meta-analysis to find that anonymity does not release antisocial impulse but amplifies the salient norm (Postmes & Spears, 1998).

The social identity approach completed the inversion. The crowd does not subtract identity; it supplies one, shifting members from personal to shared social identity whose norms pattern their conduct, set its targets, and define its limits (Reicher, 1984; Reicher et al., 1995). That reframing carried real consequences: it explained how crowd conflict escalates through the intergroup dynamic with police rather than erupting from a latent mob, and it reformed public-order practice accordingly (Stott et al., 2012); and it overturned the mass-panic myth, showing that shared identity under common threat produces collective resilience and mutual aid far more reliably than selfish stampede (Mawson, 2005; Drury, 2018). The honest summary is that mass behavior is neither mindless nor identityless: it is the meaningful, norm-governed, often orderly expression of a social identity that the crowd itself brings into being—and that the formal threshold tradition reminds us is a property of the system, never a simple sum of its members (Granovetter, 1978).

Current Directions

The most visible recent work extends the social identity model of crowds beyond the street into public health and disaster management. The COVID-19 pandemic became a natural experiment in mass behavior at scale, and researchers in the social identity tradition argued—against renewed talk of public “fatigue” and selfishness—that adherence to collective measures depended on shared identity, trust, and a sense that burdens were fair, not on coercing an inherently unruly public (Reicher & Stott, 2020). The same framework now informs formal guidance for emergency planning, which treats the affected public as the first and most capable responder rather than as a hazard to be managed (Drury et al., 2019).

A second thread follows collective experience over longer timescales. Where early crowd research captured the event, newer work asks what happens after—how the emergent solidarity of a disaster endures or erodes through the months of recovery, and what sustains the community groups it spawns (Ntontis et al., 2020). A third thread is methodological: the study of the behavioural signatures of psychological crowds, such as the coordinated movement of people who share an identity, is bringing crowd dynamics within reach of precise measurement and simulation (Templeton et al., 2018). The open questions that remain concern how far findings drawn largely from Western crowds and emergencies generalise, and how online “crowds”—masses that assemble and act without physical co-presence—fit a theory built for people in the same place.

Common Misconceptions

People in crowds lose their minds and their individuality.

This is Le Bon's group-mind image, and the evidence is against it. Crowd members do not lose identity; they shift from a personal to a shared social identity whose norms pattern and limit their conduct, which is why real crowds attack some targets and spare others rather than behaving indiscriminately (Reicher, 1984).

Anonymity in a group releases people's antisocial impulses.

Meta-analysis finds that deindividuating conditions do not reliably increase antinormative behavior. Anonymity amplifies conformity to whatever norm is salient—prosocial as readily as antisocial—so its effect depends entirely on the identity in play (Postmes & Spears, 1998).

Disasters cause mass panic and selfish stampedes.

“Mass panic” is rare. People in emergencies orient toward the familiar and help strangers far more than they trample them; a shared identity born of common fate produces collective resilience, and mutual aid is the typical response, not the exception (Mawson, 2005; Drury et al., 2009).

A riot proves the rioters were a uniformly radical mob.

Threshold models show this inference is invalid. Whether a crowd cascades into action depends on the distribution of individual thresholds, so two crowds with the same average disposition can produce opposite outcomes—a mass action need not imply radical members (Granovetter, 1978).

Glossary

Collective behavior.

The sociological term for relatively spontaneous, unstructured conduct by a large number of people responding to a common situation, including crowds, rumour, fashion, and craze; studied without recourse to a group mind.

Collective psychological empowerment.

Drury and Reicher's term for the sense of efficacy and positive emotion that arises when a crowd acts on a shared identity and prevails, which can sustain participation beyond the event itself.

Collective resilience.

The mutually supportive, coordinated behavior that a crowd of strangers displays in an emergency once a shared identity emerges from their common fate; the empirical rule in disasters, in place of mass panic.

Contagion.

Le Bon's proposed mechanism by which emotions and ideas spread automatically through a crowd as if by hypnotic suggestion; central to classical crowd psychology and rejected by later work.

Crowd psychology.

The study of the mental processes and behavior of individuals in crowds; opened by Le Bon's group-mind account and transformed by the social identity approach.

Deindividuation.

A proposed state, induced by anonymity and group immersion, of reduced self-observation and weakened behavioral restraint; later recast by the SIDE model as a shift toward the salient social identity rather than a loss of self.

Elaborated social identity model.

Reicher's intergroup account (ESIM) of crowd events, on which conflict emerges from the dynamic between a crowd and an out-group such as police, rather than from a pre-existing mob.

Emergent norm theory.

Turner and Killian's theory that a crowd develops, in an ambiguous situation, a shared definition of acceptable action that pressures members to conform, so that apparent unanimity may mask the silencing of dissent.

Group mind.

Le Bon's notion of a collective “mental unity” in which the conscious personality of crowd members dissolves into a single, suggestible, emotional entity; the founding and discredited image of crowd psychology.

Mass behavior.

The collective conduct of people acting together as a crowd, mass, or public; a form of social behavior that exists only in the aggregate and is not reducible to individual intentions decided in advance.

Mass panic.

The popular model of emergency crowds as reduced by fear to a selfish, antisocial stampede; largely a myth, since flight orients toward the familiar and mutual aid predominates.

SIDE model.

The Social Identity model of Deindividuation Effects (Reicher, Spears & Postmes), on which anonymity in a group makes a shared social identity salient and so increases conformity to that group's norms rather than releasing impulse.

Social identity.

The part of a person's self-concept derived from membership in a group; when it becomes salient in a crowd, it supplies the shared norms that pattern collective action.

Threshold model.

Granovetter's formal account on which each person joins a collective action once a threshold proportion of others has acted, so the outcome is a cascade determined by the distribution of thresholds, not the average disposition.

Value-added theory.

Smelser's account on which an episode of collective behavior requires an accumulating sequence of determinants—conduciveness, strain, generalised belief, precipitant, mobilisation, and social control—each necessary for the next.

Key Researchers

Gustave Le Bon

(1841–1931; French social psychologist). Author of The Crowd (1895), the founding text of crowd psychology, whose group-mind and contagion account framed—by provoking its rejection—every perspective that followed. Wikipedia · Wikidata

John Drury

(Professor of Social Psychology, University of Sussex). Extended the social identity approach to mass emergencies, establishing collective resilience as the typical response to disaster and translating it into emergency-planning guidance. ORCID · Google Scholar · Wikipedia

Tom Postmes

(Professor of Social Psychology, University of Groningen). Co-developed the SIDE model and, with Russell Spears, produced the meta-analysis that overturned the classical deindividuation account of crowd behavior. ORCID · Google Scholar · Faculty Page

Stephen D. Reicher

(Bishop Wardlaw Professor of Social Psychology, University of St Andrews). Founded the social identity approach to crowds with his analysis of the St Pauls riot, co-developed the SIDE model and the elaborated social identity model, and reshaped the psychology of collective action. Google Scholar · Faculty Page · Wikipedia

Russell Spears

(Professor of Social Psychology, University of Groningen). Co-developer of the SIDE model, who with Tom Postmes reinterpreted deindividuation as a shift toward the salient social identity rather than a loss of self. ORCID · Google Scholar · Faculty Page

Clifford Stott

(Professor of Social Psychology, Keele University). A leading authority on crowd behavior and public-order policing, whose identity-based model of football crowds reformed policing practice away from the group-mind assumption. Google Scholar · Faculty Page · Wikipedia

Frequently Asked Questions

What is mass behavior in psychology?

Mass behavior is the collective conduct of people acting together as a crowd, a mass, or a public—from an evacuation to a protest to a fashion craze. It is studied as a form of social behavior that exists only in the aggregate and is not simply the sum of individual intentions decided in advance (Turner & Killian, 1987).

Do people really lose their individuality in a crowd?

No. The idea that crowds dissolve individuality into a “group mind” comes from Le Bon and is not supported by evidence. Crowd members shift from a personal to a shared social identity whose norms actually pattern and limit their behavior, which is why real crowds act selectively rather than indiscriminately (Reicher, 1984).

What is deindividuation, and does anonymity make people antisocial?

Deindividuation is a proposed state of reduced self-awareness and restraint in groups. But meta-analysis finds anonymity does not reliably increase antisocial behavior; instead it increases conformity to whatever norm is salient—prosocial or antisocial—as the SIDE model predicts (Postmes & Spears, 1998).

What is the social identity approach to crowds?

It is the view, originating with Stephen Reicher, that crowd action expresses a shared social identity rather than a loss of self. The identity supplies the norms that set the crowd's targets and limits, and crowd conflict is understood as an intergroup process—often shaped by how police respond (Reicher, 2001).

Does mass panic really happen in disasters?

Rarely. The “mass panic” image is largely a myth: people in emergencies orient toward the familiar and help strangers far more than they trample them. A shared identity born of common fate produces collective resilience, making mutual aid the typical response (Mawson, 2005; Drury et al., 2009).

How does policing affect crowd behavior?

Policing that treats a whole crowd as a dangerous mob and uses indiscriminate force tends to create disorder by uniting the crowd around a shared sense of illegitimate treatment. A graded, identity-sensitive approach that facilitates lawful aims and differentiates the few from the many keeps the peace (Stott et al., 2012).

What are threshold models of collective behavior?

Threshold models, due to Mark Granovetter, hold that each person joins a collective action once a certain proportion of others already has. Because the outcome is a cascade driven by the distribution of thresholds, two crowds with the same average disposition can behave completely differently (Granovetter, 1978).

How is collective behavior explained without a group mind?

Sociological theories did this first: emergent norm theory holds that a crowd develops a shared definition of acceptable action in the moment, while Smelser's value-added theory holds that collective behavior requires an accumulating chain of structural conditions. Both treat crowd conduct as meaningful and situated rather than mindless (Turner & Killian, 1987; Smelser, 1962).

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