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Summary Article: Mob Psychology
From The Corsini Encyclopedia of Psychology and Behavioral Science

Crowds are defined as “co-acting, shoulder-to-shoulder, anonymous, casual, temporary, and unorganized collectivities” (Brown, (1954), p. 840). According to Floyd Allport (1924), “A crowd is a collection of individuals who are all attending and reacting to some common object, their reactions being of a simple prepotent sort and accompanied by strong emotional responses” (p. 292). Crowds can be subdivided according to whether they are active or passive, the former being a mob and the latter an audience. Mobs are further classified according to the dominant behavior of participants, whether aggressive, escapist, acquisitive, or expressive.

Aggressive mobs, which include riot and lynch mobs, involve a display of aggression toward persons or objects. The dominant behavior of escapist mobs is one of panic, as during a fire in a theater. Orderly escape is not panic. According to Brown (1954), “Panic is emotional and irrational. The escape behavior of the fear-driven mob must either be maladaptive from the point of view of the individual, or, if personally adaptive, the behavior must ruthlessly sacrifice the interests of others who also seek to escape” (p. 858). Acquisitive mobs are similar to escapist mobs in that both involve a competition for some object that is in short supply—tickets to the theater in the case of the acquisitive mob, and exits from the theater in the case of the escapist mob. Expressive mobs represent a wastebasket category that includes all mobs not in the first three categories. Included here is behavior that can best be described by the obsolete word revelous: behavior that might be displayed at religious revivals, sporting events, and rock music concerts.

Although there is no universal agreement among theorists, certain features tend to be attributed to mobs, such as like-mindedness, or “mental homogeneity,” and emotionality. Gustav Le Bon (1903), in his classic work, The Crowd, explained the mental homogeneity of mobs in terms of “contagion”—a mechanical, disease-like spreading of affect from one member to another. More recent research suggests that contagion is not mechanical, but rather is dependent on a number of conditions. Milgram and Toch (1969) suggest that the mechanism of “convergence” may also account for the seeming mental homogeneity of mobs: likeminded individuals tend to converge and join mobs. Thus, homogeneity precedes rather than follows from membership in the mob. Brown (1954) questioned the homogeneity of aggressive mobs and suggested that the composition of such mobs could be ordered in terms of mob members’ readiness to deviate from conventional norms of society. He identified five types of participants, ranging from the “lawless,” whose actions trigger the mob, to the “supportive onlookers,” who stand on the fringes shouting encouragement.

A central issue in the study of mob behavior is determining why restraints that produce conventional behavior break down when individuals find themselves in a crowd. Two important mechanisms that account for the violation of conventional behavior in crowds are (1) the loss of responsibility through anonymity and (2) the impression of universality. Both mechanisms are enhanced by the size of the crowd. Le Bon (1903) and many others have pointed out that aggressive mob members find it easier to act out their impulses because of the difficulty legal authorities have in singling them out and holding them responsible for their actions. Mob participants will feel safer from legal reprisals in large crowds because the sheer size of the crowd will pose impediments to identification and apprehension by the authorities.

Allport (1924) and more recently Turner and Killian (1957) have contended that an individual is swayed by the mob because of a belief that if everyone else is acting in a certain way, the actions cannot be wrong—the mob simply redefines the norm for correct behavior. In their “emergent norm theory,” Turner and Killian (1957) take issue with the causal role of emotional contagion and argue instead that people act the way they do in crowds because the crowd helps to define the situation and the appropriate behavior. In the crowd context, the less anonymous people are to their coacting peers, the greater their conformity to crowd norms. The greater the number of crowd participants, the stronger the impression of universality. Crowd size has different implications for aggressive as opposed to acquisitive and escapist mobs. Whereas in aggressive mobs, a larger number of crowd members enhances beliefs in anonymity and impressions of universality, in acquisitive and escapist mobs, a large number of crowd members increases the competition for scarce resources (e.g., theater tickets, escape exits), thereby amplifying crowd responses.

Until recently, mob psychology has attracted little attention from social psychologists. Thanks to the efforts of Stephen Reicher, interest in the subject has been re-kindled. Taking a social identity perspective, Reicher cites evidence from experimental and field studies showing that social identity forms the basis of much of mob behavior. People define themselves in part in terms of the groups to which they belong. Crowd or mob actions represent an expression of this identity. Thus, rather than losing their sense of identity in crowds, mob behavior acts to reaffirm participants’ identity.

See also


  • Allport, F. H. (1924). Social psychology. Boston: Houghton Mifflin.
  • Brown, R. (1954). Mass phenomena. In Lindzey, G. (Ed.), Handbook of social psychology (Vol. 2, pp. 833-876). Cambridge, MA: Addison-Wesley.
  • Le Bon, G. (1903). The crowd. London: Unwin.
  • Milgram, S., & Toch, H. (1969). Collective behavior: Crowds and social movements. In Lindzey, G., & Aronson, E. (Eds.), The handbook of social psychology (2nd ed., Vol. 4, pp. 507-610). Reading, MA: Addison-Wesley.
  • Turner, R. H., & Killian, L. M. (1957). Collective behavior. Englewood Cliffs, NJ: Prentice-Hall.
  • Suggested Readings
  • Postmes, T., & Spears, R. (1998). Deindividuation and antinormative behavior: A meta-analysis. Psychological Bulletin, 123, 238-259.
  • Reicher, S. (2001). The psychology of crowd dynamics. In Hogg, M. A. & Tindale, S. (Eds.), Blackwell handbook of social psychology: Group processes (pp. 182-208). Malden, MA: Blackwell.
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