Three terms are commonly used in the broad research area that investigates positive interpersonal action: prosocial behavior, helping behavior, and altruism. ”Prosocial behavior” is the broadest of the three; it refers to any behavior that can be construed as consistent with the norms of a given society. Thus, murder, when enacted on behalf of one’s country on a battlefield, is as prosocial a behavior as intervening to prevent a crime. ”Helping behavior” refers simply to any behavior that provides some benefit to its recipient. ”Altruism” is the narrowest of the three concepts. Altruism is behavior that not only provides benefits to its recipient but also provides no benefits to the actor and even incurs some costs. If one conceives of psychological rewards as benefits to the actor, this definition of altruism is so narrow that it excludes virtually all human behavior. Hence, many social psychologists maintain simply that altruistic behavior need exclude only the receipt of material benefits by the actor. Some theorists require as part of the definition that the act be motivated ”with an ultimate goal of benefiting someone else” (Batson 1991, p. 2), but do not rule out the incidental receipt of benefits by the actor.
Related terms include philanthropy, charity, volunteering, sharing, and cooperating. Philanthropy and charity have largely come to mean donation of money or material goods. Volunteering, similarly, generally refers to giving time for the ultimate purpose of benefiting others, under the aegis of some nonprofit organization. Sharing and cooperating refer to coordinated actions among members of a group or collectivity in the service of better outcomes for the group as a whole. All of these terms may be subsumed under the generic term ”prosocial behavior,” and often under ”helping behavior,” although they would seldom meet the stringent criteria for altruism.
The origins of the contemporary study of altruism have been traced back to August Comte, who explored the development of altruism and ”sympathetic instincts.” The existence of an altruistic instinct was emphasized in McDougall’s Introduction to Social Psychology (1908) but argued against by the naturalistic observational research of Lois Murphy (1937). Early symbolic interactionists attributed altruistic behavior to the capacity to ”take the role of the other”—to imagine oneself in another person’s situation (Mead 1934). The developmental study of altruism has built on the theoretical work of Piaget (1932), who explored stages in the development of sharing behavior, as well as on the work of Kohiberg (1969) on the development of moral judgment. Hartshorne and May conducted one of the earliest series of empirical studies (1928-30), focusing on honesty and altruism in children. Sorokin (1950, 1970) wrote extensively on love and altruism, and carried out the first empirical work on informal helping and volunteering by studying individuals nominated by others as ”good neighbors.” It is only since the mid-1960s, however, that altruism has been extensively examined through systematic research.
Most social psychology textbooks attribute this upsurge of interest in altruism and helping behavior to the murder of Kitty Genovese in 1964 and the failure of the thirty-nine witnesses to intervene. The subject of widespread media coverage, this incident motivated Latane and Darley’s experimental investigations of bystander inaction, published in The Unresponsive Bystander: Why Doesn’t He Help? (1970). During the 1970s, helping behavior became one of the most popular topics in social psychological research, although this emphasis declined considerably through the 1980s and 1990s (see Batson 1998 for figures on the number of published studies by decade). Because of this beginning, the vast majority of the studies deal with intervention in the momentary problems of strangers. Only since the 1990s has there been much attention to informal and formal volunteering, charitable donation, and blood donation. Virtually all textbooks now have a topic on altruism and helping behavior, and a number of books on the topic have been published in the past three decades.
THEORIES OF ALTRUISM AND HELPING BEHAVIOR
Helping behavior has been explained within a variety of theoretical frameworks, among them evolutionary psychology, social learning, and cognitive development. One sociobiological approach maintains that helping behavior and altruism have developed through the selective accumulation of behavioral tendencies transmitted genetically. Three mechanisms have been suggested: kin selection, reciprocal altruism, and group selection (see Sober and Wilson 1998). These mechanisms explain the evolution of altruistic behavior as a function of, in turn: the greater likelihood that altruists would save kin, through perpetuating an altruistic gene shared among them; a tendency to help others who have engaged in helpful acts, presumably based on a reciprocity gene; and the greater likelihood of survival of entire groups that include a higher proportion of altruists. A second sociobiological theory maintains that helping behavior has developed through sociocultural evolution, the selective accumulation of behavior retained through purely social modes of transmission. (See Krebs and Miller  for an excellent review of this literature.) The cognitive-developmental approach to the development of helping behavior in children emphasizes the transformation of cognitive structures and experiential role-taking opportunities as determinants. Social learning theory explains altruism and helping behavior as learned through interaction with the social environment, mainly through imitation and modeling, but also through reinforcement. Reflecting the same behaviorist principles, exchange theory suggests that individuals perform helping acts while guided by the principles of maximizing rewards and minimizing costs. Helping behavior is instrumental in acquiring rewards that may be material, social, or even self-administered. A more explicitly sociological framework suggests that individuals help out of conformity to social norms that prescribe helping. Three norms have received special attention: the norm of giving, which prescribes giving for its own sake; the norm of social responsibility, which prescribes helping others who are dependent; and the norm of reciprocity, which prescribes that individuals should help those who have helped them.
Reflecting the contemporary social psychological emphasis on cognition, several decision-making models of helping behavior have guided much of the research into adult helping behavior (Latane and Darley 1970; Piliavin et al. 1981; Schwartz and Howard 1981). These models specify sequential decisions that begin with noticing a potential helping situation and end with a decision to help (or not). Research has focused on identifying those personality and situational variables that influence this decision-making process and specifying how they do so. There also has begun to be more attention to the social and sociological aspects of helping—to the context in which helping occurs, to the relationship between helper and helped, and to structural factors that may affect these interactions (Gergen and Gergen 1983; Callero 1986). A very active focus of work, mainly identified with Batson (see, e.g., Batson 1991) and Cialdini and colleagues, has been the attempt to demonstrate (or refute) the existence of ”true” altruistic motivations for helping.
RESEARCH ON ALTRUISM AND HELPING BEHAVIOR
Person Variables. There has been an extensive and confused debate, due both to definitional and measurement problems, about the existence of an altruistic personality (see Schroeder et al. 1995). There is now good evidence of a pattern of prosocial personality traits that characterize individuals whose behavior involves long-term, sustained forms of helping behavior (e.g., community mental health workers, see Krebs and Miller 1985; volunteers who work with AIDS patients, see Penner et al. 1995; Penner and Finkelstein 1998). The traits that make up the prosocial personality include empathy, a sense of responsibility, concern for the welfare of others, and a sense of self-efficacy. With regard to helping in emergencies, the evidence is stronger for person by situation effects; that is, interactions of characteristics of both individuals and situations that influence helping in emergencies. For example, self-confidence and independence can predict differentially how individuals will behave in emergency situations when there are others present or when the person is alone (Wilson 1976). And Batson and his colleagues have found that prosocial personality characteristics correlate with helping, but only when helping is egoistically motivated, not when true altruism is involved. The general proposal that individual difference factors are most effective when situa-tional pressures are weak seems generally applicable in the helping area.
Internalized values as expressed in personal norms have also been shown to influence helping. Personal norms generate the motivation to help through their implications for self-based costs and benefits; behavior consistent with personal norms creates rewards such as increased self-esteem, whereas behavior that contradicts personal norms generates self-based costs such as shame. This influence has been demonstrated in high-cost helping such as bone marrow donation (Schwartz 1977). Other personality correlates of helping are less directly related to the costs and benefits of the helping act itself. For example, information-processing styles such as cognitive complexity influence helping.
Clary and Snyder (1991) have pursued a functional approach to understanding motivations for helping. They have developed a questionnaire measure that distinguishes six potential motives for long-term volunteering (e.g. value expression, social motivation, career orientation) and have demonstrated both predictive and discriminant validity for the instrument (Clary, Snyder et al. 1998). In one study, they showed that it was not the more purely altruistic motivations that predicted long-term commitment. Temporary emotional states or moods may also affect helping. A series of studies by Isen (1970) and her colleagues demonstrate that the ”glow of good will” induces people to perform at least low-cost helping acts such as helping someone pick up a pile of dropped papers, and research by Cialdini and colleagues has shown that helping can be motivated by the need to dispel a bad mood.
Situation Variables. Characteristics of the situation also influence the decision to help. The salience and clarity of a victim’s need influence both the initial tendency to notice need and the definition of the perceived need as serious. Salience and clarity of need increase as the physical distance between an observer and a victim decreases; thus, victims of an emergency are more likely to be helped by those physically near by. Situational cues regarding the seriousness of another’s need influence whether need is defined as serious enough to warrant action. Bystanders are more likely to offer aid when a victim appears to collapse from a heart attack than from a hurt knee, for example, presumably because of perceived seriousness. The presence of blood, on the other hand, can deter helping, perhaps because it suggests a problem serious enough to require medical attention.
One of the most strongly supported findings in the area of helping is that the number of others present in a potential helping situation influences an individual’s decision to help. Darley and Latane (1968) demonstrated experimentally that the higher the number of others present, the lower the chance of any one individual helping. One process underlying this effect involves the diffusion of responsibility: the higher the number of potential helpers, the less any given individual perceives a personal responsibility to intervene. The presence of an individual who may be perceived as having special competence to help also reduces the felt responsibility of others to help. Thus, when someone in medical clothing is present at a medical emergency, others are less likely to help. A second process underlying the effect, when bystanders can see each other, involves definition of the situation. If no one moves to intervene, the group may collectively provide a social definition for each other that the event is not one that requires intervention.
Social Variables. Research has also demonstrated the influence of other social variables on helping. Darley and Latane (1968) showed experimentally that people were more likely to provide help in an emergency in the presence of a friend rather than in the presence of strangers. They reasoned that in emergency situations in which a friend does not respond, one is not likely to attribute this to lack of concern, but rather will seek other explanations. In addition, bystanders who are acquainted are more likely to talk about the situation. Thus, preexisting social relationships among bystanders affect helping. Individuals are also more likely to help others who are similar to them, whether in dress style or in political ideology. The perceived legitimacy of need, a variable defined by social norms, also affects rates of helping. In one field study of emergency intervention, bystanders were more likely to help a stranger who collapsed in a subway car if the distress was attributed to illness rather than to drunkenness (Piliavin, Rodin, and Piliavin 1969).
Other demographic variables, such as sex, age, socioeconomic status, and race have also been investigated. Race appears to affect helping mainly when the costs for helping are relatively high, or when failure to help can be attributed to factors other than prejudice (Dovidio 1984). In the study cited above (Piliavin et al. 1969) the rate of helping by white and black bystanders was unrelated to the race of the victim who appeared to be ill, but help offered to the drunk was almost always by people of his own race. Females are usually helped more than males, but who helps more depends heavily on the nature of the help required. Males tend to help females more than they help males, whereas females are equally helpful to females and males (see Piliavin and Unger 1985). This pattern may reflect stereotypic gender roles: Females are stereotyped as dependent and weaker than males. Other studies of the effect of social statuses on helping indicate, consistent with social categorization theory, that members of one’s own group tend to be helped more than outgroup members. Studies of reactions following natural disasters show that people tend to give aid first to family members, then to friends and neighbors, and last to strangers.
THE SOCIOLOGICAL CONTEXT OF HELPING
Gergen and Gergen (1983) call for increased attention to the social structural context of helping and to the interactive history and process of the helping relationship (see also Piliavin and Charng 1990). Social structure is clearly important as a context for helping. Social structure specifies the pool of social roles and meaning systems associated with any interaction (Callero, Howard, and Piliavin 1987). Social structure also influences the distribution of resources that may be necessary for certain helping relationships. One needs money to be able to donate to a charity and medical expertise to be able to help earthquake victims. Wilson and Musick (1997) have presented data in support of a model using both social and cultural capital as predictors of involvement in both formal and informal volunteering. Social structure also determines the probability of both social and physical interaction among individuals and thus influences the possibility of helping.
Interaction history is also crucial to understanding helping behavior. If a relationship has been positive and mutually supportive, this context suggests that beneficial actions should be defined as helping. If a relationship has been characterized by competition and conflict, this context does not support defining beneficial action as helping. In this case, alternative, more self-serving motivations may underlie helping. Thus the provision of U.S. foreign aid to countries with which the United States has had conflict is often viewed as a strategic tool, whereas when such aid has been provided to countries with which the United States has had positive relationships, it is viewed generally as genuine helping. Such patterns illustrate this influence of interaction history on the interpretation of helping behavior.
Another sociological approach emphasizes helping as role behavior and is guided by Mead’s (1934) conception of roles as patterns of social acts framed by a community and recognized as distinct objects of the social environment. Roles define individual selves and thus also guide individual perception and action. Helping behavior has been shown to express social roles. A series of studies of blood donors (Callero, Howard, and Piliavin 1987; Piliavin and Callero 1991) demonstrate that role-person merger (when a social role becomes an essential aspect of self) predicts blood donation, independent of the effects of both personal and social norms, and is more strongly associated with a history of blood donation than are social or personal norms. This study demonstrates the importance of helping for self-validation and reproduction of the social structure as expressed in roles. More recent research has shown similar effects for identities tied to volunteering time and giving money (Grube and Piliavin in press; Lee, Piliavin, and Call in press). This attention to concepts such as roles, interaction history, and social structure is evidence of the sociological significance of altruism and helping behavior.
CROSS-CULTURAL RESEARCH IN ALTRUISM
Until the last few decades, little work had been done systematically comparing altruism and helping behavior across cultures. Beginning in the 1970s, researchers have compared helping in rural and urban areas, rather consistently finding that helping of strangers, although not of kin, is more likely in less densely populated areas all around the world. In a real sense, urban and rural areas have different ”cultures”; small towns are more communal or collective, while cities are more individualistic. A review of other cross-cultural comparisons (Ting and Piliavin forthcoming) examines similarities and differences not only in the helping of strangers but also in the development of moral reasoning, socialization of prosocial behavior, and participation in ”civil society.” The collectivism-individualism distinction across societies provides a good organizing principle for understanding many of the differences that are found. Not only do societies differ in the level of helping, but in the pattern. For example, in communal societies, the difference between the amount of help offered to ingroup and outgroup members is exaggerated in comparison with the more individualistic societies.
ALTRUISM RESEARCH IN OTHER FIELDS
Scholars from many fields other than social psychology have also addressed the question of altruism. The long debate in evolutionary biology regarding the possibility that altruism could have survival value appears to have been answered in the affirmative (Sober and Wilson 1998). Some authors (e.g. Johnson 1986; Rushton 1998) in fact view patriotism or ethnic conflict, or both, as rooted in altruism fostered by kin selection. Game theorists have discovered that in repeated prisoner’s dilemma games and public goods problems, some individuals consistently behave in more cooperative or altruistic ways than do others (Liebrand 1986). Even economists and political scientists, who have long held to the belief that all motivation is essentially selfish, have begun to come to grips with evidence (such as voting behavior and the public goods issue) that indicates that this is not true (see Mansbridge 1990; Clark 1998).
Recommended reading. The interested reader is referred Schroeder et al., The Psychology of Helping and Altruism (1995) for a relatively nontechnical overview of the field, or Batson, ”Altruism and Prosocial Behavior” (1998) for a briefer, more technical approach emphasizing work demonstrating that ”true altruism” can be a motivation for helping. For an excellent examination of approaches to the topic of altruism by economists and political scientists, read Mansbridge, Beyond Self-Interest (1990). For an engaging read on the topic of both evolutionary and psychological altruism, try Sober and Wilson’s Unto Others (1998). Finally, for a view toward the practical application of ideas from altruism research, read Oliner et al., Embracing the Other (1992). (Full citations for these works are in the references that follow.)