About these endnotes

About these endnotes

This is where we provide references and in-depth information about everything in the Kindness playbook.


We honor and thank the scientists and their teams whose research on prosocial behavior, social support, and well-being inspired this Playbook. Any errors or omissions are ours.

How we define this strength

Prosocial behavior—i.e., the opposite of antisocial behavior—is broadly defined as actions undertaken to help others. See Wispé (1972) for one of the earliest usages, and Batson and Powell (2003) and Penner, Dovidio, Piliavin and Schroeder (2005) for more recent perspectives. Typically, prosocial behavior refers to actions that one takes to help others, like pulling a drowning person out of a river or bringing coffee for coworkers. However, as reviewed by social support expert Shelley Taylor (2011), in reality, people regularly give each other numerous kinds of support, including informational support (knowledge sharing and co-processing), instrumental support (tangible help, including favors or resource-sharing), and emotional support (warmly reassuring another person of his or her worth). These types of support introduce the possibility of kind acts based on physical touch, action, sharing, and verbal interaction.

Benefits of kindness

Numerous studies have found a correlation between being kind—for instance, by volunteering or donating—with all sorts of good outcomes, including happiness and decreased mortality (Dunn, Aknin, & Norton, 2008; Glanville, Paxton & Wang, 2016; Gruenwald, Liao, & Seeman, 2012; Post, 2005). An avalanche of experimental work further reveals that, in general, kindness tends to make people feel happy (see Curry, Rowland, Van Lissa, Ziotowitz, McAlaney, & Whitehouse, 2018, for a review).

Peer effects

9- to 11-year-old children instructed to perform three acts of kindness per week (over four weeks) became more popular with their peers than did those who visited three places each week (Layous, Nelson, Oberle, Schonert-Reichl, & Lyubomirsky, 2012).

Self-signaling effects

Less is known about why acts of kindness make people feel happier. However, the most common explanations are based on the notion that human beings have three fundamental psychological needs: they need to believe that they have autonomy, that they are competent, and that they are socially connected (Deci & Ryan, 1985).

First, social interactions with other people play a clear role in the benefits of kindness. One study found that charitable giving only made givers happier when they interacted with a representative of the charity (Aknin, Dunn, Sandstrom, & Norton, 2013). Second, prosocial behavior has been shown to lead individuals to perceive themselves as more competent and autonomous (Chancellor, Margolis, Jacobs Bao, & Lyubomirsky, 2018), thus boosting well-being.

Pulse Check

Paying attention to what other people want or need may be key to effective relationship building. In fact, it is possible that the actual helpfulness of a prosocial act to the recipient may depend on whether it is done with responsiveness—that is, whether the act is a) based on an understanding of the other’s actual needs, b) indicating value and support for the other person, and c) supporting them to fulfill their personal needs and goals (Reis & Clark, 2013).

Considering how much my actions mean to others can help in reframing a negative experience as a positive one. Benefit-finding has been shown to be linked with better well-being and lower depression across many studies (Helgeson, Reynolds, & Tomich, 2006).

Regularly recounting kind acts can be helpful, as some research has found that simply recounting one’s kindnesses has positive effects similar to actually doing more kind acts (Ko, Margolis, Revord, & Lyubomirsky, 2018). Additionally, this might create a positive feedback loop, in which recalling past acts leads to future kind acts (Anik, Aknin, Norton, & Dunn, 2009; Aknin, Dunn, Sandstrom, & Norton, 2013; Layous, Nelson, Kurtz, & Lyubomirsky, 2016).

Making “If ___, then ___” plans can aid in habit formation. Known as “implementation intentions,” plans about what you will do when an opportunity arises can increase the likelihood of achieving these goals (Gollwitzer, 1999; Sheeran, Webb, & Gollwitzer, 2005).


Aknin, L. B., Dunn, E. W., & Norton, M. I. (2012). Happiness runs in a circular motion: Evidence for a positive feedback loop between prosocial spending and happiness. Journal of Happiness Studies13, 347-355.

Aknin, L. B., Dunn, E. W., Sandstrom, G. M., & Norton, M. I. (2013). Does social connection turn good deeds into good feelings?: On the value of putting the ‘social’ in prosocial spending. International Journal of Happiness and Development1(2), 155-171.

Anik, L., Aknin, L. B., Norton, M. I., & Dunn, E. W. (2009). Feeling good about giving: The benefits (and costs) of self-interested charitable behavior. Working paper, Harvard Business School, Cambridge, MA.

Batson, C. D., & Powell, A. A. (2003). Altruism and prosocial behavior. In I. B. Weiner (Ed.), Handbook of Psychology (pp. 453-484). Hoboken, N.J.: John Wiley & Sons, Inc.

Chancellor, J., Margolis, S. M., Jacobs Bao, K., & Lyubomirsky, S. (2018). Everyday prosociality in the workplace: The benefits of giving, getting, and glimpsing. Emotion, 18, 507-517

Curry, O. S., Rowland, L. A., Van Lissa, C. J., Zlotowitz, S., McAlaney, J., & Whitehouse, H. (2018). Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor. Journal of Experimental Social Psychology, 76, 320–329.

Deci, E., & Ryan, R. M. (1985). Intrinsic motivation and self-determination in human behavior. Springer Science & Business Media.

Dunn, E. W., Aknin, L. B., & Norton, M. I. (2008). Spending money on others promotes happiness. Science319, 1687-1688.

Glanville, J. L., Paxton, P., & Wang, Y. (2016). Social capital and generosity: A multilevel analysis. Nonprofit and Voluntary Sector Quarterly, 45(3), 526–547.

Gollwitzer, P. M. (1999). Implementation intentions: Strong effects of simple plans. American Psychologist54(7), 493.

Gruenewald, T. L., Liao, D. H., & Seeman, T. E. (2012). Contributing to others, contributing to oneself: Perceptions of generativity and health in later life. Journals of Gerontology Series B: Psychological Sciences and Social Sciences67(6), 660-665.

Helgeson, V. S., Reynolds, K. A., & Tomich, P. L. (2006). A meta-analytic review of benefit finding and growth. Journal of Consulting and Clinical Psychology74(5), 797.

Ko, K., Margolis, S., Revord, J., & Lyubomirsky, S. (2018). Comparing the effects of performing and recalling acts of kindness. Manuscript submitted for publication.

Layous, K., Nelson, S. K., Kurtz, J. L., & Lyubomirsky, S. (2016). What triggers prosocial effort? A positive feedback loop between positive activities, kindness, and well-being. The Journal of Positive Psychology, 1–14.

Layous, K., Nelson, S. K., Oberle, E., Schonert-Reichl, K. A., & Lyubomirsky, S. (2012). Kindness counts: Prompting prosocial behavior in preadolescents boosts peer acceptance and well-being. PLOS ONE7, e51380.

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

Post, S. G. (2005). Altruism, happiness, and health: It’s good to be good. International journal of behavioral medicine12(2), 66-77.

Reis, H. T. & Clark, M. S. (2013). Responsiveness. In J. Simpson & L. Campbell (Eds.), The Oxford handbook of close relationships (pp. 400-423). Oxford: Oxford University Press.

Sheeran, P., Webb, T. L., & Gollwitzer, P. M. (2005). The interplay between goal intentions and implementation intentions. Personality and Social Psychology Bulletin31(1), 87-98.

Taylor, S. E. (2011). Social support: A review. In Howard S. Friedman (Ed.), Oxford Handbook of Health Psychology (pp. 189–214). New York: Oxford University Press.

Wispé, L. G. (1972). Positive forms of social behavior: An overview. Journal of Social Issues, 28, 1-20.