8. Helping and Altruism

Understanding Altruism: Self and Other Concerns

Learning Objectives

  1. Understand the differences between altruism and helping, and explain how social psychologists try to differentiate the two.
  2. Review the roles of reciprocity and social exchange in helping.
  3. Describe the evolutionary factors that influence helping.
  4. Summarize how the perceptions of rewards and costs influence helping.
  5. Outline the social norms that influence helping.

 

Altruism refers to any behavior that is designed to increase another person’s welfare, and particularly those actions that do not seem to provide a direct reward to the person who performs them (Batson, Ahmad, & Stocks, 2011; Dovidio, Piliavin, Schroeder, & Penner, 2006; Penner, Dovidio, Piliavin, & Schroeder, 2005). Rather than being the exception to the rule, recent research seems to indicate that these kinds of behaviors are intuitive, reflexive, and even automatic (Zaki & Mitchell, 2013). Altruism occurs when we donate blood, when we stop to help a stranger who has been stranded on the highway, when we volunteer at a homeless shelter or donate to a charity, or when we get involved to prevent a crime from occurring. Every day there are numerous acts of helping that occur all around us. As we will see, some of these represent true altruism, whereas others represent helping that is motivated more by self-concern. And, of course, there are also times when we do not help at all, seeming to not care about the needs of others.

Helping is strongly influenced by affective variables. Indeed, the parts of the brain that are most involved in empathy, altruism, and helping are the amygdala and the prefrontal cortex, areas that are responsible for emotion and emotion regulation (Figure 8.2, “Empathy and Helping in the Human Brain”).

Figure 8.2 Empathy and Helping in the Human Brain

Figure 8.2 Empathy and Helping in the Human Brain

This figure shows the areas of the human brain that are known to be important in empathy and helping. They include the amygdala (area 1) and sections of the prefrontal cortex (areas 2 and 3). From Lieberman (2010).

Kinship

Is the tendency to help others, at least in part, a basic feature of human nature? Evolutionary psychologists believe so. They argue that although helping others can be costly to us as individuals, altruism does have a clear benefit for the group as a whole. Remember that in an evolutionary sense the survival of the individual is less important than the survival of the individual’s genes (McAndrew, 2002). Therefore, if a given behavior such as altruism enhances our reproductive success by helping the species as a whole survive and prosper, then that behavior is likely to increase fitness, be passed on to subsequent generations, and become part of human nature.

If we are altruistic in part to help us pass on our genes, then we should be particularly likely try to care for and to help our relatives. Research has found that we are indeed particularly helpful to our kin (Madsen et al., 2007; Stewart-Williams, 2007). Burnstein, Crandall, and Kitayama (1994) asked students in the United States and Japan to report how they would respond to a variety of situations in which someone needed help. The students indicated that in cases in which a person’s life was at stake and the helping involved a lot of effort, time, and danger, they would be more likely to help a person who was closely related to them (for instance, a sibling, parent, or child) than they would be to help a person who was more distantly related (for example, a niece, nephew, uncle, or grandmother). People are more likely to donate kidneys to relatives than to strangers (Borgida, Conner, & Manteufel, 1992), and even children indicate that they are more likely to help their siblings than they are to help a friend (Tisak & Tisak, 1996).

genetic

Figure 8.3 We are particularly helpful to people who share our genetic background. Source: Father and Son by Stephen Marchetti (https://www.flickr.com/photos/csb555/3352401914) used under CC BY SA 2.0 License (https://creativecommons.org/licenses/by-sa/2.0/); Sharing raspberry with grandpa by Sean Dreilinger (https://www.flickr.com/photos/seandreilinger/3839386942) used under CC BY NC SA 2.0 license (https://creativecommons.org/licenses/by-nc-sa/2.0/); Cooking with Nana by Eden, Janine, and Jim (https://www.flickr.com/photos/edenpictures/3850514726) used under CC BY SA 2.0 License (https://creativecommons.org/licenses/by-sa/2.0/)

 

Table 8.1, “Percentage of Genetic Material Shared by the Members of Each Category,” shows the average extent to which we share genes with some of the people we are genetically related to. According to evolutionary principles, this degree of genetic closeness should be positively correlated with the likelihood that we will help each of those people. Do you think that your own likelihood of helping each of the people listed corresponds to the degree to which you are genetically related to that person?

Table 8.1 Percentage of Genetic Material Shared by the Members of Each Category

Identical monozygotic twins 100%
Parents, children, siblings, and fraternal (dizygotic) twins 50%
Half-sibling, grandparent, and grandchild 25%
Cousins, great-grandchildren, great-grandparents, great-aunts, great-uncles 12.5%
Unrelated persons, such as a marital partner, brother-in-law or sister-in-law, adopted or step-sibling, friend, or acquaintance 0%
*Source: Neyer and Lang (2003).

Our reactions to others are influenced not only by our genetic relationship to them but also by their perceived similarity to us. We help friends more than we help strangers, we help members of our ingroups more than we help members of outgroups, and we are even more likely to help strangers who are more similar to us (Dovidio et al., 1997; Krupp, DeBruine, & Barclay, 2008; Sturmer, Snyder, Kropp, & Siem, 2006). It is quite possible that similarity is an important determinant of helping because we use it as a marker—although not a perfect one—that people share genes with us (Park & Schaller, 2005; Van Vugt & Van Lange, 2006).  Cialdini, Brown, Lewis, Luce, and Neuberg (1997) have proposed that it is the sense of perceived similarity—the sense of ‘‘oneness’’ between the helper and the individual in need—that motivates most helping.

Reciprocity and Social Exchange

Although it seems logical that we would help people we are related to or those we perceive as similar to us, why would we ever help people to whom we are not related? One explanation for such behavior is based on the principle of reciprocal altruism (Trivers, 1971). Reciprocal altruism is the idea that if we help other people now, they will return the favor should we need their help in the future. Thus by helping others, we both increase our chances of survival and reproductive success and help others increase their chances of survival too. Over the course of evolution, those who engage in reciprocal altruism should be able to reproduce more often than those who do not, thus enabling this kind of altruism to continue. Reciprocal altruism means that people even may help total strangers, based on the assumption that doing so is useful because it may lead others to help them (when help is most needed) in the future.

One fact that might help convince you that altruism is in fact evolutionarily adaptive is that many animals also engage in reciprocal altruism. Birds emit an alarm to nearby birds to warn them of a predator even at a potential cost to themselves. Dolphins may support sick or injured animals by swimming under them and pushing them to the surface so they can breathe. Male baboons threaten predators and guard the rear of the troop as it retreats. And even bats have a buddy system in which a bat that has had a successful night of feeding will regurgitate food for its less fortunate companion (Wilkinson, 1990).

Altruism can even be found in low-level organisms, such as the cellular slime molds (Figure 8.4, “Altruism”). Slime molds are groups of cells that live as individuals until they are threatened by a lack of food, at which point they come together and form a multicellular organism in which some of the cells sacrifice themselves to promote the survival of other cells in the organism. Altruism, then, is truly all around us.

altruism

Figure 8.4 Altruism is found in many organisms including even cellular slime molds (upper right). Source: Macaca fuscata social grooming by Noneotuho (http://en.wikipedia.org/wiki/File:Macaca_fuscata,_grooming,_Iwatayama,_20090201.jpg) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en); Acrasis Rosea by Shirley Chio (http://en.wikipedia.org/wiki/File:Acrasis_rosea_31330.jpg) used under CC BY SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/deed.en); Lovebird by Peter Békési (https://www.flickr.com/photos/pbekesi/3131154201/) used under CC BY SA 2.0 license (https://creativecommons.org/licenses/by-sa/2.0/); Cheetahs by William Warby (https://www.flickr.com/photos/wwarby/7188662412/) used under CC BY 2.0 licensen (https://creativecommons.org/licenses/by/2.0/)

 

Reciprocal altruism is one example of the general principle of social exchange. We frequently use each other to gain rewards and to help protect ourselves from harm, and helping is one type of benefit that we can provide to others. In some cases, this exchange reflects overt cooperation, such as when two students take notes for each other in classes that they miss or when neighbors care for each other’s pets while one of them is away. In other cases, the exchange may be more subtle and indirect: for instance, when we help someone we don’t really know, with the expectation that someone else may help us in return someday.

Social Reinforcement and Altruism: The Role of Rewards and Costs

Although there continues to be a lively debate within the social psychological literature about the relative contributions of each factor, it is clear that helping is both part of our basic human biological nature and also in part learned through our social experiences with other people (Batson, 2011).

The principles of social learning suggest that people will be more likely to help when they receive rewards for doing so. Parents certainly realize this—children who share their toys with others are praised, whereas those who act more selfishly are reprimanded. And research has found that we are more likely to help attractive rather than unattractive people of the other sex (Farrelly, Lazarus, & Roberts, 2007)—again probably because it is rewarding to do so.

Darley and Batson (1973) demonstrated the effect of the costs of helping in a particularly striking way. They asked students in a religious seminary to prepare a speech for presentation to other students. According to random assignment to conditions, one half of the seminarians prepared a talk on the parable of the altruistic Good Samaritan; the other half prepared a talk on the jobs that seminary students like best. The expectation was that preparing a talk on the Good Samaritan would prime the concept of being helpful for these students.

After they had prepared their talks, the religion students were then asked to walk to a nearby building where the speech would be recorded. However, and again according to random assignment, the students were told that they had plenty of time to get to the recording session, that they were right on time, or that they should hurry because they were already running late. On the way to the other building, the students all passed a person in apparent distress (actually a research confederate) who was slumped in a doorway, coughing and groaning, and clearly in need of help. The dependent variable in the research was the degree of helping that each of the students gave to the person who was in need (Figure 8.5, “The Costs of Helping”).

Darley and Batson found that the topic of the upcoming speech did not have a significant impact on helping. The students who had just prepared a speech about the importance of helping did not help significantly more than those who had not. Time pressure, however, made a difference. Of those who thought they had plenty of time, 63% offered help, compared with 45% of those who believed they were on time and only 10% of those who thought they were late. You can see that this is exactly what would be expected on the basis of the principles of social reinforcement—when we have more time to help, then helping is less costly and we are more likely to do it.

Figure 8.5

Figure 8.5

The seminary students in the research by Darley and Batson (1973) were less likely to help a person in need when they were in a hurry than when they had more time, even when they were actively preparing a talk on the Good Samaritan. The dependent measure is a 5-point scale of helping, ranging from “failed to notice the victim at all” to “after stopping, refused to leave the victim or took him for help.”

Of course, not all helping is equally costly. The costs of helping are especially high when the situation is potentially dangerous or when the helping involves a long-term commitment to the person in need, such as when we decide to take care of a very ill person. Because helping strangers is particularly costly, some European countries have enacted Good Samaritan laws that increase the costs of not helping others. These laws require people to provide or call for aid in an emergency if they can do so without endangering themselves in the process, with the threat of a fine or other punishment if they do not. Many countries and states also have passed “angel of mercy” laws that decrease the costs of helping and encourage people to intervene in emergencies by offering them protection from the law if their actions turn out not to be helpful or even harmful. For instance, in Germany, a failure to provide first aid to someone in need is punishable by a fine. Furthermore, to encourage people to help in any way possible, the individual providing assistance cannot be prosecuted even if he or she made the situation worse or did not follow proper first aid guidelines (Bundesministerium der Justiz und für Verbraucherschutz, 2014).

In addition to learning through reinforcement, we are also likely to help more often when we model the helpful behavior of others (Bryan & Test, 1967). In fact, although people frequently worry about the negative impact of the violence that is seen on TV, there is also a great deal of helping behavior shown on TV. Smith et al. (2006) found that 73% of TV shows had some altruism and that about three altruistic behaviors were shown every hour. Furthermore, the prevalence of altruism was particularly high in children’s shows.

 

role models

Figure 8.6 Altruism and Observational Learning. Altruism is learned in part through observational learning of positive role models. Source: Papa’s Workshop by Vicki Watkins (https://www.flickr.com/photos/jakesmome/2129067885) used under CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/); Fishing with dad by Randy Griffin (https://www.flickr.com/photos/47745061@N05/5966884852) used under CC BY ND 2.0 (https://creativecommons.org/licenses/by-nd/2.0/)

 

Viewing positive role models provides ideas about ways to be helpful to others and gives us information about appropriate helping behaviors. Research has found a strong correlation between viewing helpful behavior on TV and helping. Hearold (1980) concluded on the basis of a meta-analysis that watching altruism on TV had a larger effect on helping than viewing TV violence had on aggressive behavior. She encouraged public officials and parents to demand more TV shows with prosocial themes and positive role models. But just as viewing altruism can increase helping, modeling of behavior that is not altruistic can decrease altruism. Anderson and Bushman (2001) found that playing violent video games led to a decrease in helping.

There are still other types of rewards that we gain from helping others. One is the status we gain as a result of helping. Altruistic behaviors serve as a type of signal about the altruist’s personal qualities. If good people are also helpful people, then helping implies something good about the helper. When we act altruistically, we gain a reputation as a person with high status who is able and willing to help others, and this status makes us better and more desirable in the eyes of others. Hardy and Van Vugt (2006) found that both men and women were more likely to make cooperative rather than competitive choices in games that they played with others when their responses were public rather than private. Furthermore, when the participants made their cooperative choices in public, the participants who had been more cooperative were also judged by the other players as having higher social status than were the participants who had been less cooperative.

Finally, helpers are healthy! Research has found that people who help are happier and even live longer than those who are less helpful (Brown, Nesse, Vinokur, & Smith, 2003).

Social Norms for Helping

The outcome of reinforcement for and modeling of helping is the development of social norms of morality—standards of behavior that we see as appropriate and desirable regarding helping (Eisenberg & Fabes, 1998). One norm that we all are aware of and that we attempt to teach our children is based on the principles of equity and exchange. The reciprocity norm is a social norm reminding us that we should follow the principles of reciprocal altruism—if someone helps us, then we should help that person in the future, and we should help people now with the expectation that they will help us later if we need it. The reciprocity norm is found in everyday adages like “Scratch my back and I’ll scratch yours” and in religious and philosophical teachings such as the golden rule: “Do unto others as you would have them do unto you.” The reciprocity norm forms the basis of human cooperation and is found in every culture. For instance, you can see a list of variations of the golden rule as expressed in 21 different religions, at http://www.religioustolerance.org/reciproc.htm. Because the rule is normally followed, people generally do help others who have helped them (Whatley, Webster, Smith, & Rhodes, 1999).

Because helping following the reciprocity norm is based on the return of earlier help and the expectation of a future return from others, it might not seem so much like true altruism to you. But we might also hope that our children internalize another relevant social norm that seems more altruistic—the social responsibility norm. The social responsibility norm tells us that we should try to help others who need assistance, even without any expectation of future paybacks. The social responsibility norm involves a sense of duty and obligation, in which people are expected to respond to others by giving help to those in need of assistance. The teachings of many religions are based on the social responsibility norm that we should, as good human beings, reach out and help other people whenever we can.

Research Focus

Moral Hypocrisy

We have seen that the reciprocity norm teaches us that we should help others, with the expectation of a future return, and that the social responsibility norm teaches us that we should do the right thing by helping other people whenever we can, without the expectation of a payback. And most of us believe that we should be helpful to others. The problem is that these goals may not always be easy for us to follow because they represent a classic case in which one of the basic human motives (other-concern) conflicts with another basic human motive (self-concern). Trying to do the best thing for ourselves in the short term may lead us to take the selfish road—taking advantage of the benefits that others provide us without returning the favor. Furthermore, we may be particularly likely to act selfishly when we can get away with it. Perhaps you can remember a time when you did exactly that—you acted in a selfish way but attempted nevertheless to appear to others not to have done so.

Daniel Batson and his colleagues (Batson, Thompson, Seuferling, Whitney, & Strongman, 1999) created a simple moral dilemma in the laboratory that pitted the desires of individual student research participants against the interests of other students. They compared what the students said they should do with what they actually did.

Each participant was told that there were two tasks being used in the research: in the positive task the participants would engage in an interesting task and have an opportunity to compete for a $30 prize, but in the neutral task the task was described as boring and there was no opportunity to win anything. The moral dilemma was created when the experimenter informed the student participants that there was another student who had supposedly come to the experiment at the same time, and that each student had to be assigned to one of the two tasks. Furthermore, it was the job of the student participant to determine who should get which task.

The students were told that they could make the decision however they wanted and that the other student would never know who had made the decision. And they were also given a coin that they could use to help them make the decision if they wanted to use it. The coin was clearly marked—on one side it said “SELF to POSITIVE” and on the other side it said “OTHER to POSITIVE.” The participants were then left alone in a room and asked to determine who should get the positive task and then to indicate what they thought the right decision should be.

In terms of what they thought they should do, Batson and his colleagues found that of the 40 students who participated in the experiment, 31 said that flipping the coin was the most morally right thing to do, five said assigning the other participant to the positive consequences task was the most morally right decision, and four said that there was no morally right way to assign the tasks. These results show that the students believed that being generous, or at least fair, was appropriate. This would suggest that most students would have flipped the coin and chosen whatever side came up.

It turned out that 12 of the participants decided not to flip the coin at all. Of these 12, 10 assigned themselves to the positive task and two gave the positive task to others. These students were clearly putting self-concern ahead of other-concern. But what about the 28 students who chose to flip the coin? They were clearly trying to do the “right” thing by being fair. By chance, we would have expected that about 14 of these 28 students would have assigned the other person to the positive task, because the coin would have come up “OTHER to POSITIVE” about half of the time. But in fact only four actually did so; the other 24 took the positive task themselves, a significant difference from what would have been expected by chance if the participants had fairly used the actual results of the coin flip.

It appears that the students who flipped the coin wanted to be fair—they flipped the coin to see who would get the positive task. But in the end, they did not act on the principles of fairness when doing so conflicted with their self-interest. Rather, they tended to accept the results of the coin toss when it favored them but rejected it when it did not. Batson’s research makes clear the trade-offs that exist between helping ourselves and helping others. We know that helping is the right thing to do, but it hurts!

 

Key Takeaways

  • Altruism refers to any behavior that is designed to increase another person’s welfare, and particularly those actions that do not seem to provide a direct reward to the person who performs them.
  • The tendency to help others is at least in part an evolutionary adaptation. We are particularly helpful to our kin and to people we perceive as being similar to us. We also help people who are not related or similar as the result of reciprocal altruism. By cooperating with others, we increase our and others’ chances of survival and reproductive success.
  • We are more likely to help when we are rewarded and less likely when the perceived costs of helping are high.
  • Social norms for helping include the reciprocity norm, which reminds us that we should follow the principles of reciprocal altruism, and the social responsibility norm, which tells us that we should try to help others who need assistance, even without any expectation of future payback.
  • Helping frequently involves a trade-off between self-concern and other-concern. We want to help, but self-interest often keeps us from doing so.

Exercises and Critical Thinking

  1. Determine whether the following behaviors are, or are not, altruism. Consider your answer in terms of your ideas about altruism, but also consider the role of the person and the situation as well as the underlying human motivations of self-concern and other-concern.
  • Idris donates a litre of blood in exchange for $10.
  • Bill stops to help an attractive woman on the highway change a flat tire.
  • In 2007, the U.K. band Radiohead decided to buck the recording industry system and offer its new album In Rainbows directly to fans at whatever price they felt like paying. Although they could have downloaded the songs for free, thousands of people paid something anyway.
  • When Sherry renews her driver’s license, she checks off the box that indicates that she is willing to donate her organs to others when she dies.
  • Nawaz volunteers once a week at a local soup kitchen.
  • George is a Buddhist and believes that true self-understanding comes only from selflessly helping others.

References

Anderson, C. A., & Bushman, B. J. (2001). Effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, and prosocial behavior: A meta-analytic review of the scientific literature. Psychological Science, 12(5), 353–359.

Batson, C. D. (2011). Altruism in humans. New York, NY: Oxford University Press.

Batson, C. D., Ahmad, N., & Stocks, E. L. (2011). Four forms of prosocial motivation: Egoism, altruism, collectivism, and principalism. In D. Dunning (Ed.), Social motivation. (pp. 103–126). New York, NY: Psychology Press.

Batson, C. D., Thompson, E. R., Seuferling, G., Whitney, H., & Strongman, J. A. (1999). Moral hypocrisy: Appearing moral to oneself without being so. Journal of Personality and Social Psychology, 77(3), 525–537.

Borgida, E., Conner, C., & Manteufel, L. (Eds.). (1992). Understanding living kidney donation: A behavioral decision-making perspective. Thousand Oaks, CA: Sage.

Brown, S. L., Nesse, R. M., Vinokur, A. D., & Smith, D. M. (2003). Providing social support may be more beneficial than receiving it: Results from a prospective study of mortality. Psychological Science, 14(4), 320–327.

Bryan, J. H., & Test, M. A. (1967). Models and helping: Naturalistic studies in aiding behavior. Journal of Personality and Social Psychology, 6(4, Pt.1), 400–407.

Bundesministerium der Justiz und für Verbraucherschutz. (2014). German criminal code. (M. Bohlander, Trans.). Retrieved from http://www.gesetze-im-internet.de/englisch_stgb/englisch_stgb.html#p2729

Burnstein, E., Crandall, C., & Kitayama, S. (1994). Some neo-Darwinian decision rules for altruism: Weighing cues for inclusive fitness as a function of the biological importance of the decision. Journal of Personality and Social Psychology, 67(5), 773–789.

Cialdini, R. B., Brown, S. L., Lewis, B. P., Luce, C., & Neuberg, S. L. (1997). Reinterpreting the empathy-altruism relationship: When one into one equals oneness. Journal of Personality and Social Psychology, 73(3), 481–494.

Darley, J. M., & Batson, C. D. (1973). “From Jerusalem to Jericho”: A study of situational and dispositional variables in helping behavior. Journal of Personality and Social Psychology, 27(1), 100–108.

Dovidio, J. F., Gaertner, S. L., Validzic, A., Matoka, K., Johnson, B., & Frazier, S. (1997). Extending the benefits of recategorization: Evaluations, self-disclosure, and helping. Journal of Experimental Social Psychology, 33(4), 401–420.

Dovidio, J. F., Piliavin, J. A., Schroeder, D. A., & Penner, L. (2006). The social psychology of prosocial behavior. Mahwah, NJ: Lawrence Erlbaum.

Eisenberg, N., & Fabes, R. A. (Eds.). (1998). Prosocial development. Hoboken, NJ: John Wiley & Sons.

Farrelly, D., Lazarus, J., & Roberts, G. (2007). Altruists attract. Evolutionary Psychology, 5(2), 313–329.

Hardy, C. L., & Van Vugt, M. (2006). Nice guys finish first: The competitive altruism hypothesis. Personality and Social Psychology Bulletin, 32(10), 1402–1413.

Hearold, S. L. (1980). Meta-analysis of the effects of television on social behavior. Dissertation Abstracts International, 40(8-B), 3902–3903.

Krupp, D. B., Debruine, L. M., & Barclay, P. (2008). A cue of kinship promotes cooperation for the public good. Evolution and Human Behavior, 29(1), 49–55.

Lieberman, M. D. (2010). Social cognitive neuroscience. In S. T. Fiske, D. T. Gilbert, & G. Lindzey (Eds.), Handbook of social psychology (5th ed., Vol. 1, pp. 143–193). Hoboken, NJ: John Wiley & Sons.

Madsen, E. A., Tunney, R. J., Fieldman, G., Plotkin, H. C., Dunbar, R. I. M., Richardson, J.-M., & McFarland, D. (2007). Kinship and altruism: A cross-cultural experimental study. British Journal of Psychology, 98(2), 339–359.

McAndrew, F. T. (2002). New evolutionary perspectives on altruism: Multilevel-selection and costly-signaling theories. Current Directions in Psychological Science, 11(2), 79–82.

Neyer, F. J., & Lang, F. R. (2003). Blood is thicker than water: Kinship orientation across adulthood. Journal of Personality and Social Psychology, 84(2), 310–321.

Park, J. H., & Schaller, M. (2005). Does attitude similarity serve as a heuristic cue for kinship? Evidence of an implicit cognitive association. Evolution and Human Behavior, 26(2), 158–170.

Penner, L. A., Dovidio, J. F., Piliavin, J. A., & Schroeder, D. A. (2005). Prosocial behavior: Multilevel perspectives. Annual Review of Psychology, 56, 365–392.

Smith, S. W., Smith, S. L., Pieper, K. M., Yoo, J. H., Ferris, A. L., Downs, E., & Bowden, B. (2006). Altruism on American television: Examining the amount of, and context surrounding, acts of helping and sharing. Journal of Communication, 56(4), 707–727.

Stewart-Williams, S. (2007). Altruism among kin vs. nonkin: Effects of cost of help and reciprocal exchange. Evolution and Human Behavior, 28(3), 193–198.

Sturmer, S., Snyder, M., Kropp, A., & Siem, B. (2006). Empathy-motivated helping: The moderating role of group membership. Personality and Social Psychology Bulletin, 32(7), 943–956.

Tisak, M. S., & Tisak, J. (1996). My sibling’s but not my friend’s keeper: Reasoning about responses to aggressive acts. Journal of Early Adolescence, 16(3), 324–339.

Trivers, R. L. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46, 35–57.

Van Vugt, M., & Van Lange, P. A. M. (2006). Psychological adaptations for prosocial behavior: The altruism puzzle. In M. Schaller, J. Simpson, & D. Kenrick (Eds.), Evolution and social psychology (pp. 237–262). New York, NY: Psychology Press.

Whatley, M. A., Webster, J. M., Smith, R. H., & Rhodes, A. (1999). The effect of a favor on public and private compliance: How internalized is the norm of reciprocity? Basic and Applied Social Psychology, 21(3), 251–259.

Wilkinson, G. S. (1990, February). Food sharing in vampire bats. Scientific American, 262, 76–82.

Zaki, J., & Mitchell, J. P. (2013). Intuitive prosociality. Current Directions in Psychological Science, 22(6), 466-470.

Creative Commons License
This is a derivative of Principle of Social Psychology by Charles Stangor used under CC BY-NC-SA. This work, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.