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history, usually age in different ways. For example, the enjoyment of ‘‘midlife’’ experienced at around age 50 by cohort members studied in the 1990s may not be felt by some future cohort until age 85.

Intercohort Perspectives. Broader than the intracohort focus, is a focus on the lives of members of two or more successive cohorts who are growing older under differing historical or sociocultural conditions. Studies of intercohort differences in the late-twentieth century demonstrated for other sciences what sociologists had learned early: the central principle that the process of aging is not immutable or fixed for all time, but varies across and within cohorts as society changes (Riley 1978). Such studies have shown that members of cohorts already old differ markedly from those in cohorts not yet old in such respects as standard of living, education, work history, age of menarche, experience with acute vs. chronic diseases, and perhaps most importantly the number of years they can expect to live. These cohort differences cannot be explained by evolutionary changes in the human genome, which remains much the same from cohort to cohort; instead, they result from a relatively unchanging genetic background combined with a continually changing society (Riley and Abeles 1990, p.iii). Thus the

finding of cohort differences has pointed to possible linkages of lives with particular social or cultural changes over historical time, or with particular ‘‘period’’ events such as epidemics, wars, or depressions (e.g., Elder and Rockwell 1979). These linkages are useful in postulating explanations for changes—or absence of changes—in the process of aging.

Studies of cohort differences focus on aging processes at either the individual or the collective level. At the individual level, cohort membership is treated as a contextual characteristic of the individual, and then analyzed together with education, religion, and other personal characteristics to investigate how history and other factors affect the heterogeneous ways individuals grow older (e.g.,

Messeri 1988; but see Riley 1998). At the collective level, the lives of members are aggregated within each cohort to examine alterations in average patterns of aging. Striking advances have recently been made in the data banks available for intercohort comparisons. Archived data from many large-scale studies now cover long periods of history, multiple societies, and multidisciplinary aspects of the life

course; and repeated longitudinal studies are being launched, such as the National Institute on Aging’s Health and Retirement Study (HRS) and Asset and Health Dynamics Among the Oldest

Old (AHEAD) (cf. Campbell 1994; O’Rand and

Campbell 1999).

Cohort perspectives are useful, not only in explaining past changes in aging processes, but also in improving forecasts of future changes. Unlike the more usual straight projections of crosssectional information, forecasts based on cohorts can be informed by established facts about the past lives of people in each of the cohorts already alive (e.g., Manton 1989). Thus, if cohorts of teenagers today are on the average less healthy, less cared for, or less prepared for life than their parents were at the same age (National Association of State Boards of Education 1990), the lives of both offspring and parents will predictably also differ in the future when both have grown older.

COMPOSITIONAL PERSPECTIVES.

Complementing sociological work on cohort differences (or similarities) in the aging process are studies of how cohort succession contributes to formation and change in the age composition of the population. Thus in Figure 1, the perpendicular lines indicate how cohorts of people fit together at given historical periods to form the crosssectional age strata of society; and how, as society changes, new cohorts of people are continually aging and entering these strata, replacing the previous incumbents.

Single Period of Time. In Figure 1, as indicated above, a single vertical line at a given period (as in 1990) is a cross-sectional slice through all the coexisting cohorts, each with its unique size, composition, earlier life experiences, and historical background. This familiar cross-sectional view of all the age strata is often denigrated because its misinterpretation is the source of the life-course fallacy—that is, the erroneous assumption that cross-sectional age differences refer directly to the process of aging, hence disregarding the cohort differences that may also be implicated (Riley 1973). That people who are differentially located in the age composition of society differ not only in age but also in cohort membership was dramatized early by Mannheim ([1928] 1952) and Ryder

(1968); yet persistent failure to comprehend this duality has perpetuated numerous false stereotypes (e.g., that intelligence or physical functioning begin inevitable declines at very early ages).

Properly interpreted, of course, a cross-sec- tional perspective has its special uses: for describing current differences and similarities, social relationships, and interactions among coexisting people who differ in age-cum-cohort membership. Thus, for example, issues of ‘‘intergenerational equity’’ require explication by both age and cohort, as a larger share of the federal budget is reportedly spent on cohorts of people now old than on cohorts of children (Duncan, Hill, and Rodgers 1986; Preston 1984).

Across Time. Comprehension of the underlying dynamics of the age strata requires going beyond the single cross-sectional snapshot to a sequence of cross-sections (the moving perpendicular line in Figure 1), as successive cohorts interact with historical trends in the society (Ryder 1965; Riley 1982). Historical change means not only that new cohorts are continually entering the system through birth or immigration, while others are leaving it through death or emigration (e.g., men tend to die earlier than women, and blacks earlier than whites). Historical change also means that the members of all existing cohorts are simultaneously aging and thus moving from younger to older strata. As successive cohorts move concurrently through the system, they affect the age strata in several ways. They can alter the numbers and kinds of people in particular strata, as each cohort starts the life course with a characteristic size, genetic makeup, sex ratio, racial and ethnic background, and other properties that are subsequently modified through migration, mortality, and environmental contact. The succession of cohorts can also affect the capacities, attitudes, and actions of people in particular strata as the members of each cohort bring to society their experiences with the social and environmental events spanned by their respective lifetimes.

The most significant alterations in the age composition of modern societies stem from the dramatic and unprecedented increases in the longevity of successive cohorts. Age pyramids diagramming the age composition of the United States in 2010 compared with 1955, for example, demonstrate that entirely new strata have been added at

the oldest ages (Taeuber 1992)—strata of old people who are healthier and more competent than their predecessors (Manton, Corder, and Stallard

1997). The advent of these ‘‘new’’ old people is already having untold consequences: Individuals now have time to spread education, work, family activities, and leisure more evenly over their long lives, and wider structural opportunities are needed in society for the age-heterogenous population.

SOCIAL STRUCTURAL PERSPECTIVES

Cohorts, as described above, are composed of people, who age and fit together in strata to form the composition of the population; but cohorts also shape, and are shaped by social structures— the surrounding families, communities, work organizations, educational institutions, and the like. Against the backdrop of history, social structures, like lives, tend to change, and two ‘‘dynamisms’’— changing structures and changing lives—are in continuing interplay, as each influences the other.

Thus full understanding of cohorts requires understanding their reciprocal relations with structures (as in Foner and Kertzer 1978; Mayer 1988).

Toward this end, some studies examine how the processes of aging and cohort flow relate to structures, while other studies examine the congru- ence—or lack of congruence—between age composition and social structures.

Aging and Structures . Because cohorts differ in size and character, and because their members age in new ways (the diagonal lines in Figure 1), they exert collective pressures for adjustments— not only in people’s ideas, values, and beliefs—but also in role opportunities throughout the social institutions.

As one example, the influences of cohort differences in size were defined early by Joan Waring’s (1975) powerful analysis of ‘‘disordered cohort

flow.’’ This disordered flow has been dramatically brought to attention as the Baby Boom cohorts first pressed for expansions in the school systems and the labor force, and will become the twentyfirst century ‘‘senior boom’’ that will exacerbate the inadequacy of roles for the elderly. Later, as large cohorts were followed by smaller successors, ways were sought to reduce these expanded structures again. Meanwhile, as structures changed, the lives of people moving through these structures also changed.

In another example, the influences of cohort differences in norms has been analyzed as the process of ‘‘cohort norm formation’’ (Riley 1978).

As members of a cohort respond to shared historical experiences, they gradually and subtly develop common patterns of response, common definitions, and common beliefs, that crystallize into new norms and become institutionalized in altered social structures. For instance, over the past century many individual women in successive cohorts have responded to common social changes by making many millions of separate but similar personal decisions to move in new directions: to go to college, have a career, or form their families in innovative ways. Such decisions, beginning in one cohort and transmitted from cohort to cohort, can feed back into the social structures and gradually pervade entire segments of society. Thus, many new age norms have become expectations that women should work, and have stimulated the demand for new role opportunities at work and in the family for people of all ages.

Age Composition and Structures. At any given period of history, the coexisting cohorts of people that form the age strata coincide with the existing role structures (both indicated by the perpendicular lines in Figure 1). People who differ in age and experience confront the available agerelated opportunities, or lack of opportunities, in work, education, recreation, the family, and elsewhere. However, people and structures rarely fit together smoothly: there is a mismatch or ‘‘lag’’ of one dynamism behind the other.

Structural Lag. While people sometimes lag behind structures as technology advances, more frequent in modern society is the failure of structural changes to keep pace with the increasing numbers of long-lived and competent people (Riley,

Kahn, and Foner 1994). Cohorts of those who are young today have few ‘‘real-world’’ opportunities; those in the middle years are stressed by the combined demands of work and family; and those who have reached old age are restive in the prolonged ‘‘roleless role’’ of retirement. Cohorts of people now old are more numerous, better educated, and more vigorous than their predecessors were in 1920 or 1950; but few changes in the places for them in society have been made. Capable people and empty role structures cannot long coexist. Thus, implicit in the lag are perpetual pressures toward structural change.

Age Integration. Among societal responses to structural lag are current tendencies toward ‘‘age integration’’ (Riley, Foner, and Riley 1999, p.338). With pressures from the expanded numbers of age strata, many age barriers dividing education, work and family, and retirement are gradually becoming more flexible. People of different ages are more often brought together, as lifelong education means that old and young study together, as new entrepreneurships hire employees of mixed ages, as in many families four generations are alive at the same time, or as the age segregation of nursing homes is replaced by home health care with wide access to others. Where such tendencies may lead in the future is not yet known. But the interdependence between cohorts and structure is clear.

RESEARCH METHODS.

When aspects of these broad cohort perspectives are translated into empirical studies, a variety of research methods are required for specific objectives: from analyses of historical documents and subjective reports, to panel analyses and mathematical modeling, to rigorous tests of specific hypotheses. This brief overview can only hint at the diverse research designs involved in analyses of the multiple factors affecting lives of people in particular cohorts; or in the shifting role opportunities for cohort members confronting economic, religious, political, and other social institutions (for one example, see Hendricks and Cutler 1990).

Cohort Analysis. The tool most widely used in large-scale studies is ‘‘cohort analysis,’’ which takes the intercohort aging perspective—in contrast to ‘‘period analysis’’ (Susser 1969), which takes the cross-sectional perspective. (The difference is illustrated in Figure 1 by comparison of the diagonal cohort lines, in contrast to comparison of a sequence of vertical compositional slices). In his 1992 formulation of the technical aspects of cohort analysis, Ryder defines the term as ‘‘the parameterization of the life cycle behavior of individuals over personal time, considered in the aggregate, and the study of change in those parameters over historical time’’ (p. 230). He conceptualizes the cohort as ‘‘providing a macro-analytic link between movements of individuals from one to another status, and movements of the population composition from one period to the next.’’

His classic work on ‘‘demographic translation’’ sets out the mathematical procedure for moving between the cohort and the period ‘‘modes of temporal aggregation’’ (Ryder 1963, 1983).

Central to this method is the identification problem confounding many attempts at cohort analysis. This problem occurs from efforts to interpret the separate effects of three concepts—cohort, period, and age (C, P, and A)—when only two variables, such as date and years of age, are indexed. Apart from various procedures that assume one of the parameters is zero, the most appropriate solution to this problem is to specify and measure directly the three concepts used in the particular analysis (Cohn 1972; Rodgers 1982; Riley, Foner, and Waring 1988, pp. 260–261). After all, as Ryder puts it (1992, p. 228), the cohort

(C) is a set of actors, the age (A) is their age, and the period (P) stands for the social context at the time of observation..

Wide Range of Methods. Ryder’s exegesis of this particular method illustrates, through its strengths and limitations, the utility of the tripartite conceptualization of cohort perspectives as a heuristic guide. The strengths in Ryder’s formulation focus exclusively on the significance of cohorts as a macro-analytic vehicle for social change. In the broader cohort perspectives outlined here, many other methods are useful for specific objectives where cohort analysis is inappropriate. Some employ a cross-sectional approach. Others utilize intercohort comparisons to focus on aging processes at the individual as well as the collective levels. Still others complement demographic analyses of populations with examination of the related structures of social roles and institutions.

Thus, despite its signal contributions, neither cohort analysis nor any other single method can comprehend the full power of cohorts as ingredients of aging processes, age composition, and the complex interplay with social structure.

(SEE ALSO: Structural Lag)

Cohn Richard 1972 ‘‘On Interpretation of Cohort and Period Analyses: A Mathematical Note.’’ In Matilda White Riley, Marilyn Johnson, and Anne Foner, eds.,

Aging and Society: A Sociology of Age Stratification, Vol. III. New York: Russell Sage Foundation.

Dannefer, Dale 1987 ‘‘Aging as Intracohort Differentiation: Accentuation, the Matthew Effect, and the Life Course.’’ Sociological Forum 2 (spring):211–236.

Duncan, Greg J., Martha Hill, and Willard Rodgers 1986 ‘‘The Changing Fortunes of Young and Old.’’American Demographics 8:26–34.

Elder, Glenn H., Jr., and R. C. Rockwell 1979 ‘‘Economic Depression and Postwar Opportunity in Men’s Lives: A Study of Life Patterns and Mental Health.’’ In R. G. Simmons, ed., Research in Community and Mental Health, Vol. 1. Greenwich, Conn.: JAI Press.

Featherman, David L. 1981 ‘‘The Life-Span Perspective.’’ In The National Science Foundation’s 5-Year Outlook on Science and Technology, Vol. 2. Washington, D.C.: Government Printing Office.

Foner, Anne and David I. Kertzer 1978 ‘‘Transitions Over the Life Course: Lessons from Age-Set Societies.’’ American Journal of Sociology 83:1081–1104.

Hendricks, Jon, and Stephen J. Cutler 1990 ‘‘Leisure and the Structure of our Life Worlds.’’ Aging and Society 10:85–94.

Mannheim, Karl (1928) 1952 ‘‘The Problem of Generations.’’ In Paul Kecskemeti, ed., Essays on the Sociology of Knowledge. London: Routledge & Kegan Paul.

Manton, Kenneth G. 1989 ‘‘Life-Style Risk Factors.’’ In M. W. Riley and J. W. Riley, Jr., eds., The Quality of Aging: Strategies for Interventions, Special issue of The Annals (503). Newbury Park, Calif.: Sage.

———, Larry Corder, and Eric Stallard 1997 ‘‘Chronic Disability Trends in Elderly United States Populations: 1982–1994.’’ Proceedings of the National Academy of Sciences 94:2593–2598

Mayer, Karl Ulrich 1988 ‘‘German Survivors of World War II: The Impact of the Life Course of the Collective Experiences of Birth Cohorts.’’ In M. W. Riley, B. J. Huber, and B. B. Hess, eds., Social Structures and Human Lives. Newbury Park, Calif.: Sage.

Messeri, Peter 1988 ‘‘Age, Theory Choice, and the Complexity of Social Structure.’’ In M. W. Riley, B. J. Huber, and B. B. Hess, eds., Social Structures and Human Lives. Newbury Park, Calif.: Sage.

REFERENCES

Campbell, Richard T. 1994 ‘‘A Data-Based Revolution in the Social Sciences.’’ ICPSR Bulletin, XIV, 1–4.

Clausen, John A. 1986 The Life Course: A Sociological Perspective. Englewood Cliffs, N.J.: Prentice-Hall.

National Association of State Boards of Education 1990

Code Blue: Uniting for Healthier Youth. Alexandria, Va.: National Association of State Boards of Education.

Nesselroade, John R. 1991 ‘‘The Warp and the Woof of the Development Fabric.’’ In R. M. Downs, L. S.

Liben, and D. S. Palermo, eds., Visions Of Aesthetics. Hillsdale, N.J.: Lawrence Erlbaum.

O’Rand, Angela M. and Richard T. Campbell 1999 ‘‘On Reestablishing the Phenomenon and Specifying Ignorance: Theory Development and Research Design in Aging.’’ In Vern L. Bengtson and K. Warner Schaie, eds., Handbook of Theories of Aging. New York: Springer.

Preston, Samuel 1984 ‘‘Children and the Elderly: Diverse Paths for America’s Dependents.’’Demography 21:435–457.

Riley, Matilda White 1973 ‘‘Aging and Cohort Succession: Interpretations and Misinterpretation.’’ Public Opinion Quarterly 37:35–49.

———1978 ‘‘Aging, Social Change, and the Power of Ideas.’’ Daedalus 107:39–52.

———1982 ‘‘Aging and Social Change.’’ In M. W. Riley, R. P. Abeles, and M. S. Teitelbaum, eds., Aging from Birth to Death: Sociotemporal Perspectives, Vol. II, AAAS Selected Symposium 79. Boulder, Colo.: Westview Press.

———1988 ‘‘The Aging Society: Problems and Prospects.’’ In Proceedings of the American Philosophical Society, Vol. 132, No. 2, 148–153.

———1994 ‘‘A Life Course Approach.’’ In J. Z. Giele and G. H. Elder, Jr., eds., Methods of Life Course Research. Thousand Oaks: Sage.

———, and Ronald P. Abeles 1990 The Behavioral and Social Research Program at the National Institute of Aging: History of a Decade. Bethesda, Md.: National Institute on Aging, National Institutes of Health.

Riley, Matilda White, Anne Foner, and John W. Riley, Jr. 1999 In Vern L. Bengtson and K. Warner Schaie, eds., Handbook of Theories of Aging. New York: Springer.

Riley, Matilda White, Robert L. Kahn, and Anne Foner 1994 Age and Structural Lag: Society’s Failure to Provide Meaningful Opportunities in Work, Family, and Leisure. New York: Wiley.

Riley, Matilda White, Anne Foner, and Joan Waring 1988 ‘‘Sociology of Age.’’ In Neil J. Smelser, ed., Handbook of Sociology. Newbury Park, Calif.: Sage Publications.

Riley, Matilda White, Marilyn Johnson, and Anne Foner 1972 Aging and Society, Vol. III: A Sociology of Age Stratification. New York: Russell Sage Foundation.

Rodgers, Willard L. 1982 ‘‘Estimable Functions of Age, Period, and Cohort Effects.’’ American Sociological Review 47:774–787.

Ryder, Norman B. 1963 ‘‘The Translation Model of Demographic Change.’’ In Norman B. Ryder, ed.,

Emerging Techniques in Population Research. New York: Milbank Memorial Fund.

———1965 ‘‘The Cohort as a Concept in the Study of Social Change.’’ American Sociological Review 30:843–861.

———1968 ‘‘Cohort Analysis.’’ International Encyclopedia of the Social Sciences 5:546–550.

———1983 ‘‘Cohort and Period Measures of Changing Fertility.’’ In Rodolfo A. Bulatao and Ronald D. Lee, eds., Determinants of Fertility in Developing Countries. New York: Academic Press.

———1992 ‘‘Cohort Analysis.’’ In E. F. Borgatta and M. L. Borgatta, eds., Encyclopedia of Sociology, Vol. 1,. New York: MacMillan.

Schaie, K.Warner 1996 Intellectual Development in Adulthood: The Seattle Longitudinal Study. New York: Cambridge University Press.

Susser, Mervyn 1969 ‘‘Aging and the Field of Public Health.’’ In M. W. Riley, J. W. Riley, Jr., and M. E. Johnson, eds., Aging and Society, Vol. II, Aging and the Professions. New York: Russell Sage Foundation.

Taeuber, Cynthia M. 1992 ‘‘Sixty-five Plus in America.’’

Current Population Reports, P23-178RV. Washington, D.C.: U.S. Bureau of the Census.

Waring, Joan M. 1975 ‘‘Social Replenishment and Social Change.’’ American Behavioral Scientist 19:237–256.

Zuckerman, Harriet and Robert K. Merton 1972 ‘‘Age, Aging and Age Structure in Science.’’ In M. W. Riley, M. Johnson, and A. Foner, eds., Aging and Society: Volume II, A Sociology of Age Stratification. New York: Russell Sage Foundation.

MATILDA WHITE RILEY

COLLECTIVE BEHAVIOR

Collective behavior consists of those forms of social behavior in which the usual conventions cease to guide social action and people collectively transcend, bypass, or subvert established institutional patterns and structures. As the name indicates, the behavior is collective rather than individual. Unlike small group behavior, it is not principally coordinated by each-to-each personal relationships, though such relationships do play an important part. Unlike organizational behavior, it is not coordinated by formally established goals, authority, roles, and membership designations, though emergent leadership and an informal role structure are important components. The best known forms of collective behavior are rumor, spontaneous collective responses to crises such as natural disasters; crowds, collective panics,

crazes, fads, fashions, publics (participants in forming public opinion), cults, followings; and reform and revolutionary movements. Social movements are sometimes treated as forms of collective behavior, but are often viewed as a different order of phenomena because of the degree of organization necessary to sustain social action. This essay will include only those social movement theories that also have relevance for the more elementary forms of collective behavior.

Theories of collective behavior can be classi-

fied broadly as focusing on the behavior itself

(microlevel) or on the larger social and cultural settings within which the behavior occurs (macrolevel or structural). An adequate theory at the microlevel must answer three questions, namely: How is it that people come to transcend, bypass, or subvert institutional patterns and structures in their activity; how do people come to translate their attitudes into significant overt action; and how do people come to act collectively rather than singly? Structural theories identify the processes and conditions in culture and social structure that are conducive to the development of collective behavior. Microlevel theories can be further divided into action or convergence theories and interaction theories.

MICROLEVEL CONVERGENCE THEORIES

Convergence theories assume that when a critical mass of individuals with the same disposition to act in a situation come together, collective action occurs almost automatically. In all convergence theories it is assumed that: ‘‘The individual in the crowd behaves just as he would behave alone, only more so,’’ (Allport 1924, p. 295), meaning that individuals in collective behavior are doing what they wanted to do anyway, but could not or feared to do without the ‘‘facilitating’’ effect of similar behavior by others. The psychological hypothesis that frustration leads to aggression has been widely applied in this way to explain racial lynchings and riots, rebellion and revolution, and other forms of collective violence. Collective behavior has been conceived as a collective pursuit of meaning and personal identity when strains and imbalances in social institutions have made meaning and identity problematic (Klapp 1972). In order to explain the convergence of a critical mass of people experiencing similar frustrations, investigators

posit deprivation shared by members of a social class, ethnic group, gender group, age group, or other social category. Because empirical evidence has shown consistently that the most deprived are not the most likely to engage in collective protest, more sophisticated investigators assume a condition of relative deprivation (Gurr 1970), based on a discrepancy between expectations and actual conditions. Relative deprivation frequently follows a period of rising expectations brought on by improving conditions, interrupted by a setback, as in the J-curve hypothesis of revolution (Davies 1962). Early explanations for collective behavior, generally contradicted by empirical evidence and repudiated by serious scholars, characterized much crowd behavior and many social movements as the work of criminals, the mentally disturbed, persons suffering from personal identity problems, and other deviants.

Rational decision theories. Several recent convergence theories assume that people make rational decisions to participate or not to participate in collective behavior on the basis of selfinterest. Two important theories of this sort are those of Richard Berk and Mark Granovetter.

Berk (1974) defines collective behavior as the behavior of people in crowds, which means activity that is transitory, not well planned in advance, involving face-to-face contact among participants, and considerable cooperation, though he also includes panic as competitive collective behavior. Fundamental to his theory is the assumption that crowd activity involves rational, goal-directed action, in which possible rewards and costs are considered along with the chances of support from others in the crowd. Rational decision making means reviewing viable options, forecasting events that may occur, arranging information and choices in chronological order, evaluating the possible consequences of alternative courses of action, judging the chances that uncertain events will occur, and choosing actions that minimize costs and maximize benefits. Since the best outcome for an individual in collective behavior depends fundamentally on what other people will do, participants attempt to advance their own interests by recruiting others and through negotiation. Berk’s theory does not explain the origin and nature of the proposals for action that are heard in the crowd, but describes the process by which these proposals

are sifted as the crowd moves toward collaborative action, usually involving a division of labor. To explain decision making, he offers a simple equation in which the probability of a person beginning to act (e.g., to loot) is a function of the product of the net anticipated personal payoff for acting (e.g., equipment or liquor pilfered) and the probability of group support in that action (e.g., bystanders condoning or joining in the looting.)

Granovetter’s (1978) application of rational decision theory focuses on the concept of threshold. He assumes that each person, in a given situation, has a threshold number or percentage of other people who must already be engaging in a particular action before he or she will join in. Since it can be less risky for the individual to engage in collective behavior (riotous behavior, for example) when many others are doing so than when few are involved, the benefit-to-cost ratio improves as participation increases. Based on the personal importance of the action in question, individual estimation of risk, and a host of other conditions, individual thresholds will vary widely in any situation. Collective behavior cannot develop without low-threshold individuals to get it started, and development will stop when there is no one with the threshold necessary for the next escalation step. Collective behavior reaches an equilibrium, which can be ascertained in advance from knowing the distribution of thresholds, when this point is reached. Like Berk, Granovetter makes no effort to explain what actions people will value. Furthermore, intuitively appealing as the theory may be, operationalizing and measuring individual thresholds may be, for all practical purposes, impossible.

MICRO-LEVEL INTERACTION THEORIES

Contagion Theories. Early interaction theories, which lay more emphasis on what happens to people in the context of a crowd or other collectivity than on the dispositions people bring to the collectivity, stressed either the emergence of a group mind or processes of imitation, suggestion, or social contagion. Serge Moscovici (1985a, 1985b) is a defender of these early views, stressing that normal people suffer a lowering of intellectual faculties, an intensification of emotional reactions, and a disregard for personal profit in a crowd. The fundamental crowd process is suggestion, emanating from charismatic leaders. During the twentieth

century, the breakdown of social ties has created masses who form larger and larger crowds that are controlled by a few national and international leaders, creating an historically new politics or appeal to the masses.

Herbert Blumer (1939) developed a version of the contagion approach that has been the starting point for theories of collective behavior for most American scholars. Blumer explains that the

fitting together of individual actions in most group behavior is based on shared understandings under the influence of custom, tradition, conventions, rules, or institutional regulations. In contrast, collective behavior is group behavior that arises spontaneously, and not under the guidance of preestablished understandings, traditions, or rules of any kind. If sociology in general studies the social order, collective behavior consists of the processes by which that order comes into existence. While coordination in publics and social movements and involving more complex cognitive processes called interpretation interaction, coordination in the crowd and other elementary forms of collective behavior is accomplished through a process of circular reaction. Circular reaction is a type of interstimulation in which the response by others to one individual’s expression of feeling simply reproduces that feeling, thereby reinforcing the first individual’s feeling, which in turn reinforces the feelings of the others, setting in motion an escalating spiral of emotion. Circular reaction begins with individual restlessness, when people have a blocked impulse to act. When many people share such restlessness, and are already sensitized to one another, circular reaction can set in and create a process of social unrest in which the restless state is mutually intensified into a state of milling. In milling, people move or shift their attention aimlessly among each other, thereby becoming preoccupied with each other and decreasingly responsive to ordinary objects and events. In the state of rapport, collective excitement readily takes over, leading to a final stage of social contagion, the ‘‘relatively rapid, unwitting, and non-rational dissemination of a mood, impulse, or form of conduct.’’(Blumer 1939) Social unrest is also a prelude to the formation of publics and social movements. In the case of the public, the identification of an issue rather than a mood or point of view converts the interaction into discussion rather than circular reaction. Social movements begin with circular

reaction, but with persisting concerns they acquire organization and programs, and interpretative interaction prevails.

Emergent Norm Theory. Ralph Turner and Lewis Killian [(1957] 1989) criticize convergence theories for underemphasizing the contribution of interaction processes in the development of collective behavior, and found both convergence and contagion theories at fault for assuming that participants in collective behavior become homogeneous in their moods and attitudes. Instead of emotional contagion, it is the emergence of a norm or norms in collective behavior that facilitates coordinated action and creates the illusion of unanimity. The emergent norm is characteristically based on established norms, but transforms or applies those norms in ways that would not ordinarily be acceptable. What the emergent norm permits or requires people to believe, feel, and do corresponds to a disposition that is prevalent but not universal among the participants. In contrast to convergence theories, however, it is assumed that participants are usually somewhat ambivalent, so that people could have felt and acted in quite different ways if the emergent norm had been different. For example, many rioters also have beliefs in law and order and fair play that might have been converted into action had the emergent norm been different. Striking events, symbols, and keynoting—a gesture or symbolic utterance that crystallizes sentiment in an undecided and ambivalent audience—shape the norm and supply the normative power, introducing an element of unpredictability into the development and direction of all collective behavior.

Emergent norm theory differs from contagion theories in at least six important and empirically testable ways. First, the appearance of unanimity in crowds, social movements, and other forms of collective behavior is an illusion, produced by the effect of the emergent norm in silencing dissent. Second, while the collectivity’s mood and definition of the situation are spontaneously induced in some of the participants, many participants experience group pressure first and only later, if at all, come to share the collectivity’s mood and definition of the situation. Third, unlike collective excitement and contagion, normative pressure is as applicable to quiet states such as dread and sorrow as it is to excited states. Fourth,

according to emergent norm theory, a conspicuous component in the symbolic exchange connected with the development of collective behavior should consist of seeking and supplying justifications for the collectivity’s definition of the situation and action, whereas there should be no need for justifications if the feelings were spontaneously induced through contagion. Fifth, a norm not only requires or permits certain definitions and behaviors; it also sets acceptable limits, while limits are difficult to explain in terms of a circular reaction spiral. Finally, while contagion theories stress anonymity within the collectivity as facilitating the diffusion of definitions and behavior that deviate from conventional norms, emergent norm theory asserts that familiarity among participants in collective behavior enhances the controlling effect of the emergent norm.

Emergent norm theory has been broadened to make explicit the answers to all three of the key questions microlevel theories must answer: The emergent normative process as just described provides the principal answer to the question, why people adopt definitions and behavior that transcend, bypass, or contravene established social norms; participants translate their attitudes into overt action rather than remaining passive principally because they see action as feasible and timely; and action is collective rather than individual primarily because of preexisting groupings and networks and because an event or events that challenge conventional understandings impel people to turn to others for help in fashioning a convincing definition of the problematic situation. In addition, these three sets of processes interact and are mutually reinforcing in the development and maintenance of collective behavior. This elaboration of the emergent norm approach is presented as equally applicable to elementary forms of collective behavior such as crowds and to highly developed and organized forms such as social movements.

Other Interaction Theories. Although all interactional theories presume that collective behavior develops through a cumulative process, Max Heirich (1964) makes this central to his theory of collective conflict, formulated to explain the 1964–1965 year of spiraling conflict between students and the administration at the University of California, Berkeley. Common action occurs when observers perceive a situation as critical, with limited time for action, with the crisis having a simple

cause and being susceptible to influence by simple acts. Heirich specifies determinants of the process by which such common perceptions are created and the process by which successive redefinitions of the situation take place. Under organizational conditions that create unbridged cleavages between groups that must interact regularly, conflict escalates through successive encounters in which cleavages become wider, issues shift, and new participants join the fray, until the conflict becomes focused around the major points of structural strain in the organization.

Also studying collective conflict as a cumulative process, Bert Useem and Peter Kimball (1989) developed a sequence of stages for prison riots, proceeding from pre-riot conditions, to initiation, expansion, siege, and finally termination. While they identify disorganization of the governing body as the key causative factor, they stress that what happens at any one stage is important in determining what happens at the next stage.

Clark McPhail (1991), in an extensive critique of all prior work, rejects the concept of collective behavior as useless because it denotes too little and fails to recognize variation and alternation within assemblages. Instead of studying collective behavior or crowds, he proposes the study of temporary gatherings, defined as two or more persons in a common space and time frame. Gatherings are analyzed in three stages, namely, assembling, gathering, and dispersing. Rather than positing an overarching principle such as contagion or norm emergence, this approach uses detailed observation of individual actions and interactions within gatherings and seeks explanations at this level. Larger events such as campaigns and large gatherings are to be explained as the ‘‘repetition and/or combination of individual and collective sequences of actions.’’(McPhail 1991, p. 221). These elementary actions consist of simple observable actions such as clustering, booing, chanting, collective gesticulation, ‘‘locomotion,’’ synchroclapping, and many others. The approach has been implemented by precise behavioral observation of people assembling for demonstrations and other preplanned gatherings. A promised further work will help determine how much this approach will contribute to the understanding of those fairly frequent events usually encompassed by the term collective behavior.

MACROLEVEL OR STRUCTURAL

THEORIES

Microlevel theories attempt first to understand the internal dynamics of collective behavior, then use that understanding to infer the nature of conditions in the society most likely to give rise to collective behavior. In contrast, macrolevel or structural theories depend primarily on an understanding of the dynamics of society as the basis for developing propositions concerning when and where collective behavior will occur. Historically, most theories of elementary collective behavior have been microlevel theories, while most theories of social movements have been structural. Neil Smelser’s 1993value-added theory is primarily structural but encompasses the full range from panic and crazes to social movements.

Smelser attempted to integrate major elements from the Blumer and Turner/Killian tradition of microtheory into an action and structural theory derived from the work of Talcott Parsons. Smelser describes the normal flow of social action as proceeding from values to norms to mobilization into social roles and finally to situational facilities. Values are the more general guides to behavior; norms specify more precisely how values are to be applied. Mobilization into roles is organization for action in terms of the relevant values and norms. Situational facilities are the means and obstacles that facilitate and hinder attainment of concrete goals. The four ‘‘components of social action’’ are hierarchized in the sense that any redefinition of a component requires readjustment in the components below it, but not necessarily in those above. Each of the four components in turn has seven levels of specificity with the same hierarchical ordering as the components. Types of collective behavior differ in the level of the action components they aim to restructure. Social movements address either values, in the case of most revolutionary movements, or norms, in the case of most reform movements. Elementary collective behavior is focused at either the mobilization or the situational facilities level. Collective behavior is characterized formally as ‘‘an uninstitutionalized mobilization for action in order to modify one or more kinds of strain on the basis of a generalized reconstitution of a component of action.’’ (Smelser

1963 p. 71). The distinguishing feature of this action is a shortcircuiting of the normal flow of

action from the general to the specific. There is a jump from extremely high levels of generality to specific, concrete situations, without attention to the intervening components and their levels of specificity. Thus, in Smelser’s view, collective behavior is intrinsically irrational.

In order for collective behavior to occur, six conditions must be met, each of which is necessary but insufficient without the others. Smelser likens the relationship among the six determinants to the value-added process in economics, with each adding an essential component to the finished product. The first determinant is structural conduciveness, meaning that the social structure is organized in a way that makes the particular pattern of action feasible. The second determinant is structural strain, consisting of ambiguities, deprivations, conflicts, and discrepancies experienced by particular population segments. Third (and central in Smelser’s theorizing), is the growth and spread of a generalized belief that identifies and characterizes the supposed source of strain and specifies appropriate responses. The generalized belief incorporates the short-circuiting of the components of action that is a distinctive feature of collective behavior. Fourth are precipitating factors, usually a dramatic event or series of events that give the generalized belief concrete and immediate substance and provide a concrete setting toward which collective action can be directed. The fifth determinant is mobilization of participants for action, in which leadership behavior is critical. The final determinant is the operation of social control. Controls may serve to minimize conduciveness and strain, thus preventing the occurrence of an episode of collective behavior, or they may come into action only after collective behavior has begun to materialize, either dampening or intensifying the action by the way controls are applied. These determinants need not occur in any particular order.

Addressing a more limited range of phenomena, David Waddington, Karen Jones, and Chas Critcher (1989) have formulated a flashpoint model to explain public disorders that bears some resemblance to the value-added component of Smelser’s theory. Public disorders typically begin when some ostensibly trivial incident becomes a

flashpoint. The flashpoint model is a theory of the conditions that give a minor incident grave significance. Explanatory conditions exist at six levels. At

the structural level are conflicts inherent in material and ideological differences between social groups that are not easily resolvable within the existing social structure, meaning especially the state. At the political/ideological level, dissenting groups are unable to express their dissent through established channels, and their declared ends and means are considered illegitimate. At the cultural level, the existence of groups with incompatible definitions of the situation, appropriate behavior, or legitimate rights can lead to conflict. At the contextual level, a history of past conflicts between a dissenting group and police or other authorities enhances the likelihood that a minor incident will become a flashpoint. At the situational level, immediate spatial and social conditions can make public control and effective negotiation difficult. Finally, at the interactional level, the dynamics of interaction between police and protesters, as influenced by meanings derived from the other five levels, ultimately determine whether there will or will not be public disorder and how severe it will be. Unlike

Smelser, Waddington and associates make no assumption that all levels of determinants must be operative. Also, they make no explicit assumption that disorderly behavior is irrational, though their goal is to formulate public policy that will minimize the incidence of public disorders.

Resource mobilization theories have been advanced as alternatives to Smelser’s value-added theory and to most microlevel theories. Although they have generally been formulated to explain social movements and usually disavow continuity between social movements and elementary collective behavior, they have some obvious implications for most forms of collective behavior. There are now several versions of resource mobilization theory, but certain core assumptions can be identified.

Resource mobilization theorists are critical of prior collective behavior and social movement theories for placing too much emphasis on ‘‘structural strain,’’ social unrest, or grievances; on ‘‘generalized beliefs,’’ values, ideologies, or ideas of any kind; and on grass-roots spontaneity in accounting for the development and characteristics of collective behavior. They assume that there is always sufficient grievance and unrest in society to serve as the basis for collective protest (McCarthy and

Zald 1977), and that the ideas and beliefs exploited in protest are readily available in the culture

(Oberschall 1973). They see collective protest as