Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor Oliver Scott Curry ([email protected]) Lee Rowland Sally Zlotowitz John McAlaney Harvey Whitehouse September 2016
Abstract Does being kind make you happy? Recent advances in the behavioural sciences have provided a number of explanations of human social, cooperative and altruistic behaviour. These theories predict that people will be ‘happy to help’ family, friends, community members, spouses, and even strangers under some conditions. As a preliminary test of whether and to what extent these predictions are supported by the existing literature, here we conduct a systematic review and meta-analysis of the experimental evidence that kindness interventions (for example, performing ’random acts of kindness’) boost subjective well-being. Our initial search of the literature identifies 376 articles; of which 19 (21 studies) meet the inclusion criteria (total N=2,685). We find that the overall effect of kindness on well-being is small-to-medium (d = 0.38). There is also some indication of publication bias – lower quality studies tended to find larger effects – suggesting that the true effect size may be smaller still (0.31 ≤ d ≤ 0.34). We also find that the design and methodological limitations of existing studies preclude the testing of specific theories of kindness. We recommend that future research: distinguish between the effects of kindness to specific categories of people (for example, family, friends, strangers); take kindness- specific individual differences into account; and consider a wider range of distal outcome measures. Such research will advance our understanding of the causes and consequences of kindness, and help practitioners to maximise the effectiveness of kindness interventions.
Keywords: kindness, altruism, happiness, well-being, positive psychology
"1 Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor Oliver Scott Curry ([email protected]) Lee Rowland Sally Zlotowitz John McAlaney Harvey Whitehouse September 2016
Introduction Does being kind make you happy? Does doing good make you feel good?
Over the past few decades, advances in the evolutionary behavioural sciences have developed numerous theories of human social, cooperative and altruistic behaviour. These theories — kin altruism, mutualism, reciprocal altruism, and competitive altruism — make it possible to explain a variety of different ‘kinds of kindness’ (for example, love, sympathy, gratitude and heroism). And they predict that people will be ‘happy to help’ family, friends, community members, spouses, and even strangers under some conditions.
More recently, there has been growing interest in using kindness as an intervention to boost ‘subjective well-being’ (including happiness, life-satisfaction and positive affect). It has been argued that altruism — acting at a cost to benefit others – benefits the altruist as well as the beneficiary. The appeal of this ‘good news story’ is obvious: if it is true that ‘helping helps the helper’, then encouraging people to be kind(er) to others could provide a simple, accessible, inexpensive, self-sustaining and effective means of tackling a variety of social problems.
Here we outline existing theories of altruism and their relation to kindness, and consider the predictions these theories make about well-being. And in order to investigate whether and to what extent these predictions have been tested, and to give an overview of the literature as a whole, we conduct a systematic review and meta-analysis of the experimental studies of the effects of kind acts on the well-being of the actor. We end with a discussion of the limitations of the existing literature, and make recommendations for future research.
"2 The causes of kindness Humans are social animals. Their ancestors have been living in social groups for over 50 million years (Shultz, Opie, & Atkinson, 2011), and for the past 2 million years humans have been making a living as intensely collaborative hunter-gathers (Tooby & DeVore, 1987). Social life affords numerous opportunities for mutually beneficial cooperative interactions. And humans, like other social animals, have been equipped by natural selection with a variety of traits and dispositions – love, loyalty, benevolence and bravery – that enable them to seize these opportunities. In addition, the human capacity for culture – the ability to invent and share new ways of living – has allowed them to build and elaborate upon this benevolent biological foundation, with rules, norms and other social institutions that further inculcate and amplify cooperation and altruism (Hammerstein, 2003).
According to game theory – the mathematical analysis of social interaction – there is not one type of cooperation, there are many, and hence many different types of social, cooperative and altruistic behaviour (Curry, 2016; Lehmann & Keller, 2006; Nunn & Lewis, 2001; Sachs, Mueller, Wilcox, & Bull, 2004). These theories make it possible to identify and distinguish between several different ‘kinds of kindness’.
People will be kind to their families Natural selection will favour altruism when the cost to the acting gene is outweighed by the benefits to copies of that gene that reside in other individuals – that is in genetic relatives or family members (Dawkins, 1979; Hamilton, 1964). As predicted by this theory of ‘kin selection’, many organisms possess adaptations for detecting and delivering benefits (or avoiding harm) to kin (Gardner & West, 2014) — the most common example being parental care of offspring (Clutton-Brock, 1991; Royle, Smiseth, & Kölliker, 2012). Humans and their recent primate ancestors have always lived in groups composed mostly of genetic relatives (Chapais, 2014; Walker, 2014), and there is evidence to suggest that they too possess adaptations for kin altruism. Humans detect kin by means of a variety of cues, including maternal perinatal association, co-residence (Lieberman, Tooby, & Cosmides, 2003, 2007), and possibly phenotype matching (DeBruine, 2005; Mateo, 2015). A preference for helping kin has been demonstrated in numerous experiments (Curry, Roberts, & Dunbar, 2013; Madsen, et al., 2007). And human kin altruism is evident in patterns of parental (Geary & Flinn, 2001) and grandparental (Euler & Weitzel, 1996) investment, as well as its absence (Daly & Wilson, 1996). It has also been argued that
"3 sympathy – a sensitivity to the needs of others – originally evolved to facilitate parental care (Hublin, 2009; Preston & de Waal, 2002), before becoming available to facilitate other types of cooperation.
Thus, kin selection can explain kindness in the form of love, care, sympathy and compassion. And the theory predicts that these tendencies will be elicited by others who exhibit cues of genetic relatedness, especially vulnerable children. Consistent with this perspective, research has shown that people are more generous when donating to charities using images of children with negative (sad, distressed) as opposed to neutral emotional expressions (Burt & Strongman, 2005; Small & Verrochi, 2009).
People will be kind to members of their communities Natural selection will favour altruism to those with whom the actor shares a common interest – team mates, group members, coalition partners, and others who are ‘in the same boat’. Game theorists typically model such ‘mutualistic’ interactions as coordination problems (D. K. Lewis, 1969; Schelling, 1960) – including ‘stag hunts’ (Skyrms, 2004) and ‘soldiers dilemmas’ (Clutton-Brock, 2009). The benefits of ‘working together’ are evident from the ubiquity in nature of herds, shoals, flocks, and collaborative hunting (Boinski & Garber, 2000; Boos, Kolbe, Kappeler, & Ellwart, 2011), as well as the formation of alliances and coalitions (Bissonnette, et al., 2015; Harcourt & de Waal, 1992). Coordinating to mutual advantage has been a recurrent feature of the social lives of humans and their recent ancestors, especially with regard to collaborative hunting (Alvard, 2001; Alvard & Nolin, 2002), and forming coalitions to compete with rival coalitions (Wrangham, 1999). Humans have psychological adaptations for detecting coalitions by means of a variety of different ‘badges of membership’ (Kurzban, Tooby, & Cosmides, 2001; McElreath, Boyd, & Richerson, 2003; Pietraszewski, Curry, Petersen, Cosmides, & Tooby, 2015; Tooby & Cosmides, 2010); and they spontaneously form, and are altruistic to, their own groups (sometimes at the expense of other groups) (Balliet, Wu, & De Dreu, 2014; Bernhard, Fischbacher, & Fehr, 2006; Sherif, Harvey, White, Hood, & Sherif, 1954/1961; Tajfel, 1970). Coordination to mutual advantage also seems to have spurred the evolution of a sophisticated ‘theory of mind’ – the ability to think about what others are thinking and feeling (Tomasello, Carpenter, Call, Behne, & Moll, 2005; Young, Camprodon, Hauser, Pascual-Leone, & Saxe, 2010).
"4 Thus, mutualism (coordination to mutual advantage) can explain kindness in the form of loyalty, solidarity, camaraderie, civic-mindedness, community spirit, and commitment to a cause ‘greater than oneself’. And the theory predicts that these tendencies will be elicited by other members of the groups with which one identifies (including strangers) (Whitehouse & Lanman, 2014). Consistent with this perspective, research has demonstrated that geographical proximity (and perhaps perceptions of cultural and genetic similarity) is a major predictor of the size of U.S. donations to foreign communities affected by large scale natural disasters (Adams, 1986). Research has also shown that participants primed with words related to ‘connectedness’ (for example, ‘community’, ‘together’, ‘connected’, ‘relationship’) donated more money to charity (Pavey, Greitemeyer, & Sparks, 2011).
People will be kind to their friends, and others whom they might meet again Natural selection also favours altruism to those who might return the favour at a later date (Axelrod, 1984; Trivers, 1971). Under some conditions – modelled by game theorists as ‘prisoner’s dilemmas’ – cooperation can be undermined by ‘cheats’, individuals who accept the benefit of cooperation without paying the cost. In repeated interactions, a strategy of ‘conditional cooperation’ or ‘reciprocal altruism’ – which initiates and continues cooperation with cooperators, but which detects and avoids (or punishes) cheats – can overcome this ‘free-rider’ problem (Ostrom & Walker, 2002). Surprisingly, few if any examples of full blown ‘reciprocal altruism’ have been found in non-human species (Amici, et al., 2014; Clutton-Brock, 2009), although some aspects of reciprocity have been identified in cleaner fish (Bshary & Grutter, 2006), vampire bats (Carter & Wilkinson, 2013), and primates (Mitani, 2009). However, it has been argued that reciprocal social exchange has been a recurrent feature of the social lives of humans since our last common ancestors with chimpanzees 6 million years ago (Jaeggi & Gurven, 2013); and there is some suggestive evidence for trade between human groups from 82,000 years ago (Bouzouggar, et al., 2007). Humans appear to be equipped with adaptations for detecting (Cosmides & Tooby, 2005), punishing (Price, Cosmides, & Tooby, 2002), and forgiving (McCullough, Kurzban, & Tabak, 2013) ‘cheats’. And reciprocity emerges early in children’s behaviour (Harbaugh, Krause, Liday, & Vesterlund, 2002), and is used as a strategy for social exchange cross- culturally (Henrich, et al., 2005; Kocher, Cherry, Kroll, Netzer, & Sutter, 2008).
Thus, reciprocal altruism can explain kindness in the form of trust (initiating cooperation), returning favours, gratitude (for favours yet to be returned), forgiveness and friendship.
"5 The theory can also explain kindness to strangers. An altruistic act may be the start of a beautiful friendship, a way of making a new friend (after all, ‘a stranger is just a friend you haven’t met yet’). And in any case, it might be better to ‘err on the side of caution’, and be altruistic just in case you happen to see the person again (Delton, Krasnow, Cosmides, & Tooby, 2011; Krasnow, Delton, Tooby, & Cosmides, 2013).
The theory of reciprocal altruism predicts that these tendencies will most likely be elicited in repeated interactions where individuals expect to meet again, where one’s cooperative (or uncooperative) behaviour can be observed by others, and towards others who have helped in the past, or will be able to help them in the future (Kraft-Todd, Yoeli, Bhanot, & Rand, 2015). For example, in an experimental game investigating donations made in public to UNICEF, researchers found that those who gave more money away received more from their fellow players (Milinski, Semmann, & Krambeck, 2002). And in a test of eight different messages designed to increase organ donation, an appeal to ‘reciprocity’ – “If you needed an organ transplant, would you have one? If so, please help others” – was found to be the most effective (Harper, 2013; see also: Sanders, Halpern, & Service, 2013, Trial 4).
People will be kind to others when it enhances their status Natural selection can also favour altruism if it intimidates rivals or impresses potential mates. Organisms often come into conflict over resources such as food, territory, and mates (Huntingford & Turner, 1987). Although such conflicts appear purely competitive, in fact there are costs involved in conflict – time, energy, and injury – that individuals have a common interest in avoiding. One way of avoiding a damaging fight is for contestants to display reliable indicators of “fighting ability” (“resource holding power”, or “formidability”), and for the weaker party to cede the resource to the stronger. In this way, the stronger party still wins, but both avoid the costs of a real fight (Maynard Smith & Price, 1973). Such ‘ritual contests’ are widespread in nature (C. W. Hardy & Briffa, 2013; Riechert, 1998). In stable social groups, in which relative ‘power’ is already known by reputation (through direct experience or third-party observation), individuals can dispense with the contest, and allocate disputed resources by ‘rank’. Such ‘dominance hierarchies’ represent a further de-escalation of conflict, and are also widespread(Preuschoft & van Schaik, 2000). Depending on the species, displays of size, weight, age, or experience may carry the day — but conspicuous displays of altruism can also work (Gintis, Smith, & Bowles, 2001; Zahavi & Zahavi, 1997). Humans and their recent ancestors have always faced the
"6 problem of resolving conflict, because such problems are inherent in group living (Shultz & Dunbar, 2007). And all human societies feature status hierarchies, which individuals (especially males) seek to climb and derive satisfaction from climbing (Anderson, Hildreth, & Howland, 2015; Anderson, Kraus, Galinsky, & Keltner, 2012; Mazur, 2005). As predicted, humans – especially males – commonly engage in costly and conspicuous displays of prowess, resources, and even altruism (including generosity and bravery), especially in the context of mate-competition (C. L. Hardy & Van Vugt, 2006; Hawkes, 1991; Hawkes, O'Connell, & Blurton Jones, 2001; Mazur, 2005; Miller, 2000; Smith & Bleige Bird, 2000). Experiments suggest that a tendency for the strong to display status by helping the weak – noblesse oblige – is present cross-culturally (Fiddick, Cummins, Janicki, Lee, & Erlich, 2013).
Thus, ‘competitive altruism’ can explain kindness in the form of generosity, bravery, heroism, chivalry, magnanimity and public service. This includes acts of kindness to strangers. Helping a stranger may improve your status (Barclay, 2011; N. J. Raihani & Bshary, 2015) of whether the recipient is in a position to return the favour or not. And the theory predicts that these tendencies will be elicited in the presence of rivals, or potential mates, where acting altruistically may enhance one’s status. Consistent with this perspective, research has shown that male donors give more when donating to an attractive female fundraiser, especially in response to a large donation made by a competing male (Nichola J. Raihani & Smith, 2015). (See also: Bereczkei, Birkas, & Kerekes, 2007; Iredale & Van Vugt, 2011).
Summary Thus multiple theories – kin altruism, mutualism, reciprocal altruism, competitive altruism – explain multiple types of altruism, and multiple types of kindness. Although such kindness is usually directed towards family, friends, colleagues and spouses, these theories also explain kindness to strangers under some conditions. Rather than attempting to force these diverse theories and mechanisms into a single definition, for the remainder of this paper we will simply use kindness, altruism, helping, prosociality and related terms interchangeably, to refer broadly to actions that benefit others (at a cost to self), usually accompanied by benevolent subjective emotions.
"7 The consequences of kindness: Why would helping make you happy? Broadly speaking, happiness (well-being, pleasure) can be seen as an internal reward system for acting in ways that promote survival and reproduction (Buss, 2000). Happiness is: “a psychological reward, an internal signaling device that tells us that an adaptive problem has been, or is in the process of being, solved successfully” (Hill, DelPriore, & Major, 2013).
From this perspective, it is no problem to explain why ‘eating’ or ‘having sex’ makes people happy. These behaviours meet important adaptive goals. And, for the reasons outlined above, it is equally straightforward to explain why performing acts of kindness might make people happy. It is because caring for family, maintaining coalitions, trading favours and increasing status are also important adaptive goals. Indeed, we might even expect helping others to produce more happiness than helping yourself. It is precisely because helping others can sometimes give a better return on investment than helping yourself that evolution has favoured kindness in the first place.
Thus, the evolutionary behavioural science approach to altruism predicts that people will be happy to help family, friends, community members, spouses, and even strangers under some conditions.
This approach to kindness and well-being also predicts that there will be individual differences in the degree to which individuals derive satisfaction for helping specific others. Like all personality traits (Polderman, et al., 2015), various different types of cooperative behaviours have been found to be moderately heritable – including in-group favouritism (G. J. Lewis & Bates, 2010), trust (Cesarini, et al., 2008), and fairness (Wallace, Cesarini, Lichtenstein, & Johannesson, 2007). And the satisfaction derived from helping others, and establishing cooperative social relationships is no exception (Haworth, et al., 2016). In addition, there are also obvious situational and contextual factors that should make a difference. Just as a hungry person derives more pleasure from eating than a full person, we should expect individuals with a greater need or desire to establish cooperative relationships to derive more satisfaction from being kind to others. For example, lonely or isolated people — perhaps those who have moved to a new city, or a new school — might be happier to seize opportunities to make new friends, or connect with their communities, than are people who ‘have enough friends already’ or who are well-established in their communities. Ambitious people (with more resources to spare) seeking status may have a
"8 greater appetite for, and be happier to seek, opportunities for conspicuous altruism or public service — “You make a living by what you get; you make a life by what you give” as Winston Churchill didn’t say. Single people who are courting may be happier to help potential mates. Indeed, we might also expect sex differences, with women happier to help children, and men happier to perform chivalry or heroics.
To what extent have these predictions been tested, and received support, from the existing literature on well-being? In order to find out, below we conduct a systematic review and meta-analysis of the experimental literature on the effects of kind acts on the well-being of the actor.
And again, given that well-being encapsulates a range of states and associated behaviours (OECD, 2013), and is generally "measured by simply asking people about their happiness” (Dolan & Metcalfe, 2012), for the remainder of this paper we will use well- being, happiness, life-satisfaction and related terms interchangeably.
The present study The past decade has seen a growing interest in the relationship between kindness and well-being. A large number of research groups and charity organisations [see Appendix A] have been created to pursue and promote the idea that, for example, ‘random acts of kindness’ boosts the well-being, happiness and mental health not only of the recipient, but also the actor. The idea has even been explored by the UK government (Aked, Marks, Cordon, & Thompson, 2008; Aked & Thompson, 2011; Huppert, 2009; Laura Stoll, 2011). The appeal of the idea is clear: it suggests that there is a simple, effective, inexpensive and widely-available means of addressing social problems ranging from social isolation to more serious mental and physical health conditions.
What is the evidence for the claim that altruism makes the altruist happy? A large body of research has established an association between kindness and happiness and health (Anik, Aknin, Norton, & Dunn, 2009; Konrath & Brown, 2013). However, much of the research has been correlational — showing, for example, that around the world people who spend more money on others are happier (Lara B. Aknin, et al., 2013), or people who volunteer to help others are healthier (Jenkinson, et al., 2013).1
"9 While such correlational evidence is consistent with the prediction that people will be happy to help others, it is not sufficient to establish a causal relationship between kindness and happiness. After all, it’s possible that helping makes you happy, but it could also be that happiness makes you helpful, or it could be that some third variable – health, income, personality – makes you both happy and helpful.
Distinguishing correlation and cause is not a mere philosophical nicety — it has important practical implications. In the absence of a clear causal connection, kindness interventions may not work. They may waste time and money, or displace other more effective interventions. Worse, they may be counter-productive. If happiness causes helping (rather than the other way around), then forcing unhappy people to help may make them less happy still.
In order to establish that performing acts of kindness can cause happiness, what’s needed is experimental research that randomly allocates participants to kindness and non- kindness conditions, and then measures and compares their subsequent happiness. And so we undertook a systematic review and meta-analysis of this experimental literature. The review sought to answer two questions. First, to what extent have the theories of the effects of kindness on well-being outlined above been tested and supported? Second, what is the overall effectiveness of kindness interventions on well-being?
Methods In order to identify suitable experimental studies of the effects of altruism on the altruist's well-being, we conducted searches of the scientific databases Web of Science and PsychInfo for academic articles in English. The most recent search was conducted on 1st September 2016. The process is summarised in the flow diagram in Figure 1. We used the search string: (kindness OR altruis* OR prosocial OR co-operat* OR cooperat*) AND (wellbeing OR well-being OR happiness) AND (experiment* OR control OR condition OR random* OR empirical OR trial) NOT mindfulness OR meditation OR loving-kindness. This search identified 583 articles. To this we added 19 articles identified by other means (following references in books and journal articles, Google scholar searches, viewing academic researchers’ web-pages). After removing duplicates, we were left with 376 articles.
"10 This initial set of 376 articles was screened. Two researchers (LAR and OSC) read the titles and abstracts. Subsequently 328 articles were excluded for not meeting the inclusion criteria. These articles were not experimental (that is, they were qualitative or correlational); or the kindness-well-being effect was reversed (that is, they looked at whether making people happy made them kinder, or whether kindness made the recipient happy or healthy); or they were review papers presenting no new data; or they were on topics not directly relevant to the current review and in which the effect of kindness on well-being was not measured (for example, drug-alcohol rehabilitation programmes; kindness in animal husbandry; climate change and planetary wellbeing; loving-kindness meditation/mindfulness). Cases in which the researchers disagreed were given greater scrutiny and discussed, and where no consensus was reached, the articles were included in the next stage of the analysis.
The remaining 48 articles were then read in full, and assessed for appropriateness for the meta-analysis [see Appendix B for the full list]. This process excluded a further 29 records (and several studies from included articles) for reasons summarised in Table 1.2 At the end of this process we were left with 19 articles, containing a total of 21 studies that had experimentally tested the hypothesis that kindness causes well-being.
For each of these 21 studies we coded the following characteristics:
(a) theory of kindness being tested (b) mean age of sample (c) sex of participants (d) location of study (e) type of altruist (for example, whether sample was likely to be especially in need of social connection) (f) type of recipient (for example, whether family, friend, stranger) (g) the nature of the intervention (for example, ‘random act of kindness’, prosocial purchase, charitable donation) (h) size of the intervention group (i) nature of the control (for example, no treatment, self-kindness, other activity) (j) size of the control group (k) dependent measure (for example, well-being, happiness, life-satisfaction) (l) effect size (Cohen’s d)
"11 When coding studies with multiple (control) groups, and / or multiple dependent measures, we chose the most appropriate comparison (usually kindness versus neutral) and the most appropriate measure (usually some measure of happiness).
Results
Study characteristics The characteristics of the 21 studies are presented in Table 2. These 21 studies included a total of 2,685 participants (~34% male, mean age ~25.49, SD=12.39).3 The majority of participants came from Canada, USA and Europe, although there were also studies conducted in South Africa, Korea and Vanuatu. Most participants were university students, although there were also two studies with children, one study of Vanuatu villagers, and one with elderly participants.
The two most common interventions were ‘acts of kindness’ and ‘prosocial purchasing’. Typical instructions for the ‘acts of kindness’ intervention were as follows:
“During the coming week, please perform at least five acts of kindness per day and report on them in the evening, including the responses of others that you received. Examples of acts of kindness are: holding a door for someone at university, greeting strangers in the hallway, helping other students in preparing for an exam, etcetera. It does not matter whether you address your acts of kindness to people you know or not” (Ouweneel, Le Blanc, & Schaufeli, 2014).
Prosocial purchasing interventions involved giving participants a sum of money, and instructing them to spend it on someone else.
Most studies used a self-report measure of subjective well-being, happiness, life- satisfaction, or positive and negative affect. These included the Subjective Happiness Scale (SHS; S. Lyubomirsky & Lepper, 1999), the Steen Happiness Index (SHI; Seligman, Steen, Park, & Peterson, 2005), the Satisfaction With Life Scale (SWLS; Diener, Emmons, Larsen, & Griffin, 1985), and the Positive Affect and Negative Affect Scale (PANAS; Watson, Clark, & Tellegen, 1988). Three studies used more objective measures: two used other-rated smiling, and one used blood pressure.
"12 Scrutiny of the 21 studies identified a number of methodological limitations.
Crucially, from the point of view of the present study, we found that almost all of the studies were designed to investigate the effects of kindness in general; none of the studies distinguished between the different types of kindness outlined above. Hence none of the studies systematically varied the type of altruist (for example, those in need of friends, and those not in need; the majority of participants were ‘typical’ although two studies focussed on ‘socially anxious’ individuals). And none of the studies systematically varied type of recipient, for example family, colleague, friend, stranger; in most cases the recipient was left unspecified – that is, they could be ‘anyone’. This means that the predictions regarding the effects of kindness on the well-being of different types of altruists, with regard to different types of recipients, has not been tested by previous research, and could not be tested by the present meta-analysis.
We also identified a number of other potential problems.
In two studies, participants were not only not blind to the hypothesis, but were explicitly told that performing acts of kindness would improve their mood (Nelson, et al., 2015; Trew & Alden, 2015).
There was also considerable variation in control conditions. Some studies compared acting kindly with doing nothing (thus possibly confounding the effects of kindness with the effects of performing any novel fun activity), whereas others compared acting kindly with some other similarly interesting activity. (For a direct comparison of these two control conditions, see: Buchanan & Bardi, 2010).
There was also considerable variation in whether the kindness intervention involved a cost to the actor. Most ‘acts of kindness’ involved a cost; but, the ‘prosocial spending’ studies that involved a windfall payment to the participant did not. It was not even clear that spending the windfall on others even constituted an opportunity cost. In two studies, the intervention involved either keeping or donating a children’s goody bag (consisting of chocolate and juice) (Lara B. Aknin, et al., 2013; L. B. Aknin, Fleerackers, & Hamlin, 2014). For the adult participants in the study, keeping a child’s goody bag is not presumably not much of a benefit, and donating it not much of a cost.
"13 We also note that many studies exhibited many ‘researcher degrees of freedom’, through the use of multiple dependent measures; and that the results across these measures were not always consistent (for example, the intervention would improve ‘positive affect’ but not ‘life satisfaction’, or vice versa). Similarly, studies varied in duration, and were able to report results from multiple different times, not all of which were consistent. For example “The kindness intervention had a positive influence on both positive emotions and academic engagement, though not in the long run” (Ouweneel, et al., 2014).
However, in the interests of providing as broad an overview of the experimental literature as possible we erred on the side of including these studies in the meta-analysis.
Meta-analysis Meta-analysis was conducted in SPSS V21 and R, following the recommendations summarised in (Field & Gillett, 2010).
A random-effects model revealed that the mean effect size of the 21 studies was d = .38, 95% confidence interval (CI) = [.27, .49], Z = 6.92, p < .001 (see Figure 2). This is a small- to-medium effect, approximately equivalent to an increase of 0.8 on a standard 0-10 happiness scale (Helliwell, Layard, & Sachs, 2016).
A chi-square test of homogeneity of effect sizes was not significant, 2(19) 21.35, p=.38. These measures suggest considerable similarity in effect sizes across studies.
Moderator analysis suggested that the effect of age or sex on the overall effect size was not significant. However, as noted above, limitations in the design of the studies meant that further moderator analysis — for example, to investigate the effects on the well-being of different types of altruists of giving to different types of recipients — was not possible.
A file-drawer analysis, revealed that 653 unpublished, filed, or unretrieved studies would be required to bring the significance of this average effect size to nonsignificance.
However, there was evidence of significant publication or reporting bias. Visual inspection of the Funnel plots (Figure 3) suggests – and Begg's test τ(N = 21) = 0.31, p = 0.046 confirms – that smaller studies tended to find larger effects. This indicates that smaller
"14 studies finding smaller (or negative) effects have not been submitted or published. Adjusting for severe to moderate one-tailed selection suggests that the true effect size is likely to be 0.31 ≤ d ≤ 0.35 (Vevea & Woods, 2005).
Discussion The results of this systematic review and meta-analysis of the experimental kindness literature suggests that the overall effect of kindness interventions is small-to-medium (d ≤ 0.38). These effects are comparable to other positive psychology interventions (d=0.31, Sin & Lyubomirsky, 2009; d=0.44, Weiss, Westerhof, & Bohlmeijer, 2016).4 This suggests that performing acts of kindness will not change your life, but might help to nudge it in the right direction.
However, perhaps a more important discovery of the present review is that the predictions of the various theories of kindness outlined above – kin altruism, mutualism, reciprocal altruism, competitive altruism – have not been tested by previous empirical work. The studies reviewed here have instead focussed on kindness ‘in general’, rather than any of the more specific theories. This huge gap in the literature means that there are many very basic questions about the relationship between kindness and well-being that remain unanswered. For example, we do not know whether people are happier giving to family and friends, as opposed to (anonymous) strangers. (In fact, because no study investigated the effects of acting at a cost to help an (anonymous) stranger, there is no evidence (either way) on whether helping strangers makes you happy.) We do not know whether people are happier giving to needy or unlucky recipients, as opposed to affluent or lazy recipients. We do not know whether people are happier giving to children as opposed to adults; in- group as opposed to out-groups; females as opposed to males. Nor do we know whether some people benefit from performing acts of kindness more than others. We do not know whether lonely people appreciate the opportunity to reach out to others more than people whose ‘diaries are full’. We do not know whether single people are happier performing romantic gestures than couples. We do not know whether men and women are happier performing different types of kindness acts. Nor do we know how these two variables interact – that is, whether the effect of specific types of helping depend on the specific type of helper.
However, this gap – this disconnect between theory and experiment – also creates a huge opportunity for future research to enhance our understanding of the effects of kindness on
"15 well-being and, by targeting kindness interventions more effectively, maximise their therapeutic potential. After all, the overall effect size reported above is the average across all types of altruists and recipients (including those for whom it works, and those for whom it does not). With the help of more precise theories regarding which altruists, and which recipients, benefit most, future research should be able to zero-in on the kind of kindness that works best, and thus ‘put our good where it will do the most’.
To that end, in order to overcome the limitations of previous research, we make the following recommendations for future research:
There is no scientific theory that predicts that humans will be selfish under all conditions. As such, repeated tests of the folk intuition that people are selfish (and the discovery that they are not) will not help to advance the science. Future research on the effects of kindness on well-being should instead focus on developing and testing the more fine- grained predictions of the numerous theories of altruism outlined above. Specifically, future research should investigate whether people are happier to help some types of people more than others — for example, family and friends as opposed to anonymous strangers. We note that, in the present review, some of the studies with the largest effect sizes involved altruism towards ‘friends and family’ (L. B. Aknin, Broesch, Hamlin, & Van de Vondervoort, 2015; L. B. Aknin, Dunn, Whillans, Grant, & Norton, 2013; Geenen, Hoheluchter, Langholf, & Walther, 2014); and other studies have shown that ‘social connection’ with the recipient increases positive affect in the donor (L. Aknin, Dunn, Sandstrom, & Norton, 2013; L. B. Aknin, Sandstrom, Dunn, & Norton, 2011). But the findings of these studies need to be replicated more systematically. There is already a large literature on whether people behave more or less altruistically to specific types of people; it would be fairly straightforward to add measures of subjective well-being to replications and extensions of these designs.
Future research should also investigate whether performing acts of kindness benefits some types of people more than others. Do people with a greater desire for social connections benefit from being benevolent more than others? To what extent does sex, age and income influence the satisfaction derived from acts of kindness? Do personality traits, and social and moral values, play a mediating role? Do kindness interventions have a greater effect on some mental health problems than others, perhaps those most related to social interaction? And are kindness interventions particularly effective with people
"16 (re)integrating into society after being absent from it – recent immigrants, ex-offenders, recovering addicts?
Future research could also seek to generalise these findings by employing more representative community samples (including participants diagnosed with specific mental health problems) and fewer college students, as well conducting further cross-cultural experiments (Henrich, Heine, & Norenzayan, 2010). Such research could harness the unparalleled data collection opportunities provided by the internet, including on-line fundraising platforms. And, given the predicted importance of non-anonymous, face-to- face contact for cooperation and social relations, these internet methods should be combined with field experiments to further generalise the finding, establish external validity, and pilot actual interventions.
Future research could also investigate the effects of different types of altruism on the recipient which, despite a couple of interesting studies, has yet to be systematically studied (Baskerville, et al., 2000; Pressman, Kraft, & Cross, 2015). For example, are people happier to be helped by family, and friends as opposed to strangers? By in-group members as opposed to out-group? Is there any element of shame or resentment at being a ‘charity case’? Was Orwell right to argue that “A man receiving charity always hates his benefactor”. To what extent are people suspicious of the motives of altruistic strangers?
Looking further ahead, future research should also consider the long-term consequences of acts of kindness. Research on the ‘hedonic treadmill’ suggests that people might have a hedonic ‘set point’ that they return to whatever happens to them, good or bad (Ryan & Deci, 2001). So it’s possible that existing outcome measures, which tend to rely on self- report well-being, are looking for effects in the wrong places (or at the wrong times). Happiness is a quick hit, which rewards you now for doing things that have long-term benefits in the future. So, rather than chasing the fleeting effects of happiness, it might be better to employ or develop measures that assess those long-term benefits. If the function of altruistic behaviour is to help families, improve communities, make new friends, find a mate, or increase status, then studies should be measuring these outcomes. Do people allocated to the kindness condition report better relations with their families? More identification with their communities? More friends? More sexual partners (Arnocky, Piché, Albert, Ouellette, & Barclay, 2016)? More committed relationships (Kogan, et al., 2010)? More resilient marriages? More recognition and honours? More pride in one’s
"17 achievements (Sznycer, et al., submitted)? If so, then future research might be able to finally connect the two types of happiness — hedonic and eudaemonic — that have hitherto remained apart.
Conclusion Through sheer chance and serendipity random acts of kindness may have desirable consequences, perhaps in ways that could not have happened otherwise. But by their very nature, random acts are unlikely to be directed towards those who need them, or might appreciate them, the most. And we have shown that their effects are relatively modest. Could better outcomes be achieved for the same amount of effort? Might non-random acts of kindness to significant others have greater effects than random acts of kindness to strangers? Further empirical work is required to answer these important questions. This research will advance our understanding of the causes and consequences of kindness, and help practitioners to maximise the effectiveness of kindness interventions – helping people to reconnect with their families, get to know their neighbours, make new friends, meet a mate, play an active role in their communities, and compete in socially productive ways.
"18 Acknowledgements This research was supported by Kindness.org. Thanks to Caspar van Lissa and Rongqin Yu for statistical advice, to Rosalind Arden for useful discussions, and to Steve Rowland and Emma Seymour for research assistance.
"19 Table 1: Excluded studies
Exclusion Criterion Records/Studies Exluded 1. Use of kindness recall Aknin, Barrington-Leigh et al., Study 2a/b; Aknin, Dunn, rather than acts of & Norton, 2012; Aknin et al, 2013, Study 2; Aknin et al., kindness 2011 2. Counting acts of Gander et al., 2013; Kerr et al., 2015; Ng, 2016; Otake, kindness, but no new 2006 ones instigated 3. Use of expected or Aknin et al., 2015; Huang, 2016; Weinstein et al., 2010 imaginary kindness 4. No control group Pressman et al., 2015; Rudd et al., 2014 5. Comparing two kindness Social connection: Aknin et al 2013. Impact: Aknin et al, groups on a different I.V. 2013, Study 1. Intentions: Liu & Aaker, 2008; Peer pressure: Reyniers & Bhalla, 2013. Autonomy: Weinstein & Ryan, 2010 6. Including acts of Chancellor, et al., 2015; Drozd et al., 2014; Haworth, et kindness with other al., 2016; Layous et al., 2016; Meier & Stutzer, 2008; positive activity Schwartz & Sendor, 1999 interventions, i.e. no direct test of kindness 7. Incomplete description of Lyubomirsky et al., 2005 experimental details 8. Review or meta-analysis Lyubomirsky & Layous, 2013; McNulty, 2012; Sin & Lyubomirsky, 2009 9. Correlational studies Aknin, Barrington-Leigh, et al., Study 1; Dunn, et al., 2008, Study 1 & 2; Huang, 2016; Poulin et al, 2013; Proctor, 2011; Raposa, 2016
"20 Table 2 Main characteristics of studies included in the meta-analysis Study Theory Sex Age Location Donor Intervention (IV) Control Recipient(s) Outcome (DV) n1 (I) n2 (C) d Notes Prosocial Personal Anonymous Aknin, Barrington-Leigh, et al. (2013) Study 3 Prosocial 38 21 Canada / South Africa Typical Purchase Purchase Sick Children PA 100 100 0.46 Donated kids goody bag. No effect on LS. Prosocial Personal Family / Aknin, Broesch, et al. (2015) Study 1 Prosocial 42 45 Vanuatu Typical PA 13 13 0.93 Purchase Purchase Friends Donate own Donate other Aknin, Broesch, et al. (2015) Study 2 Prosocial 70 ~3 Vanuatu Typical Puppet Smiling 20 20 0.30 sweets sweets
Aknin, Dunn, et al. (2013) Study 3 Prosocial 34 21.00 Canada Typical Social/High Personal/Low Friend SHS 12 36 0.70 Impact Impact Donated kids goody bag. Other results ns. Aknin, Fleerackers, et al. (2014) Prosocial 41 19.90 USA Typical Prosocial Personal Anonymous PA 60 59 0.38 Third party rated prosocial group with greater Purchase Purchase Sick Children happiness d=0.44.
Aknin, Hamlin, et al. (2012) Prosocial 55 1.90 Canada Typical Donate own Donate other Puppet Smiling 20 20 0.46 sweets sweets Positive Affect / Socially Alden, & Trew (2013) Social Anxiety 28 19.56 Canada Anxious AK BE Anyone PA 38 43 0.50 Also included ‘Life Details’ control condition. Buchanan, & Bardi (2010) No theory 26 38.00 UK? Typical AK Novelty Anyone LS 28 28 0.21
Dunn, Aknin, et al. (2008) Study 3 Prosocial 26 na Canada Typical Prosocial Personal Anyone / H 23 23 0.67 Purchase Purchase Charity Prosocial Personal Geenen, Hoheluchter, et al. (2014) Prosocial / Egoism 21 na Germany Typical Purchase Purchase Friends H 34 34 0.70 Prosocial / East v Layous, Lee, et al. (2013) 38 na USA/Korea Typical AK Control Anyone WB 213 104 0.18 West Prosocial / Peer Layous, Nelson, et al. (2012) na 10.60 Canada Typical AK Whereabouts Anyone H 138 138 0.16 Acceptance
Martela, & Ryan (2016) Prosocial / 36 20.40 na Typical Benevolence Neutral Charity PA 34 42 0.55 No cost; freerice.com Anonymous / SDT Eastern traditions / Typical / Mongrain, Chin, et al. (2011) SIT 16 33.63 Canada Anxious AK Memory Anyone SHI 229 229 0.31 Effect was not greater for ‘anxious’ participants Nelson, Della Porta, et al. (2015) US Prosocial 39 19.11 US Typical AK Work Anyone WB 52 52 -0.10 Confounded by ‘autonomy’ manipulation. Nelson, Della Porta, et al. (2015) Korea Prosocial 54 20.77 Korea Typical AK Work Anyone WB 57 57 0.82 ns. Confounded by ‘autonomy’ manipulation. Nelson, Layous, et al. (2016) Prosocial 40 29.95 USA Typical AK Self Other/World PF 238 118 0.29 Also included Neutral control. Social Also included Neutral control. Significant O'Connell, O'Shea, et al. (2016) PPA/Social Support ~54 ~34.17 USA Typical AK Self SHS 28 31 0.33 Network effects on other outcome (RS). Positive Neutral Ouweneel, Le Blanc, et al. (2014) Study 2 Psychology / 16 20.88 Netherlands Typical AK Anyone SR-P(N)E 25 24 0.97 “The kindness intervention had a positive influence…though not in the long run.” Academic Activity Also include ‘Life Details’, control condition. Social Participants in treatment condition “were Trew, & Alden (2015) Social Avoidance 26 20.47 Canada Anxious AK Anyone PA 38 41 0.00 informed that acts of kindness may reduce Exposure anxiety by affecting mood and social interactions”. Prosocial Personal No cost. Effect on diastolic blood pressure Whillans, Dunn, et al. (2016) Study 2 Prosocial 50 72.02 USA Hypertense Anyone BP (s) 36 37 0.63 Purchase Purchase d=0.97 Note. N = sample size; Sex = % men in sample; AK=Acts of Kindness; BE=Behavioural Experiments; BPs=Blood Pressure (systolic); DSA=Depressive Symptoms; H=Happiness; LS=Life Satisfaction; na = not available; PA=Positive Affect; PF=Psychological Flourishing; RS=Relationship Satisfaction; S=Study; SA=Social Anxiety; SHI=Steen Happiness Index; SHS=Subjective Happiness Scale ; SIT=Social Interdependence Theory; SR-P(N)E=Self-report Positive and (Negative) Emotions; UG=Undergraduate; WB=Well-being. Figure 1: Flow diagram of the search and selection procedure of studies
Records identified through Additional records identified database searching through other sources (n = 583) (n = 19) Identification
Records after duplicates removed (n = 376)
Records screened Records excluded Screening (n = 376) (n = 328)
Full-text articles Full-text articles excluded assessed for eligibility (n = 29) (n = 48) 1) No kind acts, just recall n=3 2) Counting kind acts, no
Eligibility new ones n=4 3) Expected or imaginary kindness n=3 4) No control n=2 5) Comparing kindness on other IV n=4 6) Kind acts embedded with other positive activities n=6 Studies included in 7) Incomplete description quantitative synthesis of experiment n=1 Included (meta-analysis) 8) Review or meta- (n = 21) analysis n=3 9) Correlational n=3
"22 Figure 2: Forest plot for the effect of kindness acts on actor’s well-being
Nelson, Della Porta, et al. (2015; Korea) Trew, & Alden (2015) Layous, Nelson, et al. (2012) Layous, Lee, et al. (2013) Buchanan, & Bardi (2010) Nelson, Layous, et al. (2016) Aknin, Broesch, et al. (2015; S2) Mongrain, Chin, et al. (2011) O'Connell, O'Shea, et al. (2016) Aknin, Fleerackers, et al. (2014) Aknin, Barrington-Leigh, et al. (2013; S3) Aknin, Hamlin, et al. (2012) Alden, & Trew (2013) Martela, & Ryan (2016) Whillans, Dunn, et al. (2016; S2) Dunn, Aknin, et al. (2008; S3) Aknin, Dunn, et al. (2013; S3) Geenen, Hoheluchter, et al. (2014) Nelson, Della Porta, et al. (2015; USA) Aknin, Broesch, et al. (2015; S1) Ouweneel, Le Blanc, et al. (2014; S2) OVERALL
-0.5 0 0.5 1 1.5 2 Effect Size (d)
"23 Figure 3: Funnel plot for the effect of acts of kindness on actor’s well-being
0.0 0.1 0.2 Standard Error Standard 0.3 0.4
-0.5 0.0 0.5 1.0
Effect Size (d)
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"32 Appendix A: Organisations working on kindness and happiness
Ark Project Now (ARK) started with a simple question: “What if kindness became normal?” http://www.arkprojectnow.com
Be Kind to Human Kind aims to celebrate people and their kind acts and is a platform to share positive news, stories, photos, videos, poems and quotes. http://bk2hk.org/about/
Centre for Effective Altruism aims to “foster projects which use evidence and analysis to help others as much as possible” which they believe will lead to a world where everyone is “healthy, happy, fulfilled and free.” Toby Ord, a Trustee, founded Giving What We Can (https://www.givingwhatwecan.org) https://www.centreforeffectivealtruism.org
Happify defines itself as “the single [online] destination for effective, evidence-based solutions for emotional health and well-being in the 21st century.” http://www.happify.com
Life Vest Inside is a “non-profit organization dedicated to empowering the masses to engage in acts of love and kindness.” http://www.lifevestinside.com
Random Acts is “committed to creating a network of kindness through strategic partnerships with organizations from around the world.” http://www.randomacts.org
Random Acts of Kindness (RAK) is a foundation that encourages the spread of kindness in schools, communities and homes. https://www.randomactsofkindness.org
SpreadKindness is a “non-profit organization dedicated to encouraging and empowering people to practice kindness in their everyday lives. We provide individuals and groups with tools, ideas, projects and events that help make the world a kinder place.” http://www.spreadkindness.org
The Sugar Cube Factory is a website that helps people to distribute (digitally) their words of kindness around the world. http://www.sugarcubefactory.com
Some Research Centres:
The Cambridge Prosociality and Well-being Lab at the University of Cambridge investigates “the psychology and biology of human kindness and well-being.” http://cpwlab.azurewebsites.net/Welcome.aspx
The Center for Compassion and Altruism Research and Education, Stanford School of Medicine (CCARE) investigates methods for cultivating compassion and promoting altruism within individuals and society through rigorous research, scientific collaborations, and academic conferences http://ccare.stanford.edu "33
The Greater Good Science Center (GGSC) at the University of California, Berkeley “studies the psychology, sociology, and neuroscience of well-being, and teaches skills that foster a thriving, resilient and compassionate society.” http://greatergood.berkeley.edu/about
The Human Cooperation Laboratory at Yale University “brings together researchers from across the social and natural sciences to study prosociality: Why are people willing to help each other and, and how can prosociality be promoted?” Directed by Professor David Rand. http://davidrand-cooperation.com/lab/
The Institute for Research on Unlimited Love in New York has three goals. It seeks to “increase public awareness of the growing dialogue on Unlimited Love that is taking place at the interface of (1) new scientific investigations (e.g., in the health sciences, psychology, sociology, neuroscience, physics, and mathematics); (2) insights of the world’s great philosophical, spiritual and theological traditions; and (3) inspiring works of love by exemplars across the world.” http://unlimitedloveinstitute.org/about.php
The Virtual Human Interaction Lab at Stanford University, whilst not focusing on Kindness, has done research in this area (http://vhil.stanford.edu/mm/2013/rosenberg- plos-virtual-superheroes.pdf) and also into empathy (https://vhil.stanford.edu/projects/ 2015/empathy-at-scale/).
"34 Appendix B: List of 48 reviewed articles (* = included in meta-analysis) Aknin, L., Dunn, E., Sandstrom, G., & Norton, M. (2013). Does social connection turn good deeds into good feelings? *Aknin, L. B., Barrington-Leigh, C. P., Dunn, E. W., Helliwell, J. F., Burns, J., Biswas- Diener, R., . . . Norton, M. I. (2013). Prosocial spending and well-being: Cross-cultural evidence for a psychological universal. Journal of Personality and Social Psychology, 104(4), 635-652. doi:10.1037/a0031578 10.1037/a0031578.supp (Supplemental) *Aknin, L. B., Broesch, T., Hamlin, J. K., & Van de Vondervoort, J. W. (2015). Prosocial behavior leads to happiness in a small-scale rural society. Journal of Experimental Psychology: General, 144(4), 788-795. doi:10.1037/xge0000082 *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 Studies, 13(2), 347-355. doi:10.1007/s10902-011-9267-5 Aknin, L. B., Dunn, E. W., Whillans, A. V., Grant, A. M., & Norton, M. I. (2013). Making a difference matters: Impact unlocks the emotional benefits of prosocial spending. Journal of Economic Behavior & Organization, 88, 90-95. doi:10.1016/j.jebo.2013.01.008 *Aknin, L. B., Fleerackers, A. L., & Hamlin, J. K. (2014). Can third-party observers detect the emotional rewards of generous spending? Journal of Positive Psychology, 9(3), 198-203. doi:10.1080/17439760.2014.888578 *Aknin, L. B., Hamlin, J. K., & Dunn, E. W. (2012). Giving leads to happiness in young children. PLoS ONE, 7(6). doi:10.1371/journal.pone.0039211 Aknin, L. B., Sandstrom, G. M., Dunn, E. W., & Norton, M. I. (2011). It’s the recipient that counts: Spending money on strong social ties leads to greater happiness than spending on weak social ties. PLoS ONE, 6(2). doi:10.1371/journal.pone.0017018 Aknin, L. B., Van Boven, L., & Johnson-Graham, L. (2015). Abstract construals make the emotional rewards of prosocial behavior more salient. The Journal of Positive Psychology, 10(5), 458-462. doi:10.1080/17439760.2014.967801 *Alden, L. E., & Trew, J. L. (2013). If it makes you happy: Engaging in kind acts increases positive affect in socially anxious individuals. Emotion, 13(1), 64-75. doi:10.1037/ a0027761 *Buchanan, K. E., & Bardi, A. (2010). Acts of Kindness and Acts of Novelty Affect Life Satisfaction. Journal of Social Psychology, 150(3), 235-237. Chancellor, J., Layous, K., & Lyubomirsky, S. (2015). Recalling positive events at work makes employees feel happier, move more, but interact less: A 6-week randomized controlled intervention at a Japanese workplace. Journal of Happiness Studies, 16(4), 871-887. doi:10.1007/s10902-014-9538-z Drozd, F., Mork, L., Nielsen, B., Raeder, S., & Bjorkli, C. A. (2014). Better Days - A randomized controlled trial of an internet-based positive psychology intervention. Journal of Positive Psychology, 9(5), 377-388. doi:10.1080/17439760.2014.910822 *Dunn, E. W., Aknin, L. B., & Norton, M. I. (2008). Spending money on others promotes happiness. Science, 319(5870), 1687-1688. doi:10.1126/science.1150952 Gander, F., Proyer, R. T., Ruch, W., & Wyss, T. (2013). Strength-based positive interventions: Further evidence for their potential in enhancing well-being and alleviating depression. Journal of Happiness Studies, 14(4), 1241-1259. doi:10.1007/ s10902-012-9380-0 *Geenen, N. Y. R., Hohelüchter, M., Langholf, V., & Walther, E. (2014). The beneficial effects of prosocial spending on happiness: Work hard, make money, and spend it on others? The Journal of Positive Psychology, 9(3), 204-208. doi: 10.1080/17439760.2014.891154 Haworth, C. M. A., Nelson, S. K., Layous, K., Carter, K., Bao, K. J., Lyubomirsky, S., & Plomin, R. (2016). Stability and Change in Genetic and Environmental Influences on
"35 Well-Being in Response to an Intervention. PLoS ONE, 11(5). doi:10.1371/journal.pone. 0155538 Huang, Y. H. (2016). Downward Social Comparison Increases Life-Satisfaction in the Giving and Volunteering Context. Social Indicators Research, 125(2), 665-676. doi: 10.1007/s11205-014-0849-6 Kerr, S. L., O'Donovan, A., & Pepping, C. A. (2015). Can Gratitude and Kindness Interventions Enhance Well-Being in a Clinical Sample? Journal of Happiness Studies, 16(1), 17-36. doi:10.1007/s10902-013-9492-1 *Layous, K., Lee, H., Choi, I., & Lyubomirsky, S. (2013). Culture matters when designing a successful happiness-increasing activity: A comparison of the United States and South Korea. Journal of Cross-Cultural Psychology, 44(8), 1294-1303. doi: 10.1177/0022022113487591 Layous, K., Nelson, Kurtz, & Lyubomirsky. (2016). What triggers prosocial effort? A positive feedback loop between positive activities, kindness, and well-being. *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 ONE, 7(12). doi:10.1371/journal.pone.0051380 Liu, W., & Aaker, J. (2008). The happiness of giving: The time-ask effect. Journal of Consumer Research, 35(3), 543-557. doi:10.1086/588699 Lyubomirsky, S., & Layous, K. (2013). How do simple positive activities increase well- being? Current Directions in Psychological Science, 22(1), 57-62. doi: 10.1177/0963721412469809 Lyubomirsky, S., Sheldon, K. M., & Schkade, D. (2005). Pursuing happiness: The architecture of sustainable change. Review of General Psychology, 9(2), 111-131. doi: 10.1037/1089-2680.9.2.111 *Martela, F., & Ryan, R. M. (2016). Prosocial behavior increases well-being and vitality even without contact with the beneficiary: Causal and behavioral evidence. Motivation and Emotion, 40(3), 351-357. doi:10.1007/s11031-016-9552-z McNulty, J. K., & Fincham, F. D. (2012). Beyond positive psychology? Toward a contextual view of psychological processes and well-being. American Psychologist, 67(2), 101-110. doi:10.1037/a0024572 Meier, S., & Stutzer, A. (2008). Is Volunteering Rewarding in Itself? Economica, 75(297), 39-59. doi:10.1111/j.1468-0335.2007.00597.x *Mongrain, M., Chin, J. M., & Shapira, L. B. (2011). Practicing Compassion Increases Happiness and Self-Esteem. Journal of Happiness Studies, 12(6), 963-981. doi: 10.1007/s10902-010-9239-1 *Nelson, S. K., Della Porta, M. D., Bao, K. J., Lee, H. C., Choi, I., & Lyubomirsky, S. (2015). ‘It’s up to you’: Experimentally manipulated autonomy support for prosocial behavior improves well-being in two cultures over six weeks. The Journal of Positive Psychology, 10(5), 463-476. doi:10.1080/17439760.2014.983959 Nelson, S. K., Layous, K., Cole, S. W., & Lyubomirsky, S. (2016). Do Unto Others or Treat Yourself? The Effects of Prosocial and Self-Focused Behavior on Psychological Flourishing. Emotion. doi:10.1037/emo0000178 10.1037/emo0000178.supp (Supplemental) Ng, W. (2016). Use of positive interventions: Does neuroticism moderate the sustainability of their effects on happiness? The Journal of Positive Psychology, 11(1), 51-61. doi: 10.1080/17439760.2015.1025419 *O’Connell, B. H., O’Shea, D., & Gallagher, S. (2016). Enhancing social relationships through positive psychology activities: A randomised controlled trial. The Journal of Positive Psychology, 11(2), 149-162. doi:10.1080/17439760.2015.1037860
"36 Otake, K., Shimai, S., Tanaka-Matsumi, J., Otsui, K., & Fredrickson, B. L. (2006). Happy people become happier through kindness: A counting kindnesses intervention. Journal of Happiness Studies, 7(3), 361-375. doi:10.1007/s10902-005-3650-z *Ouweneel, E., Le Blanc, P. M., & Schaufeli, W. B. (2014). On being grateful and kind: Results of two randomized controlled trials on study-related emotions and academic engagement. The Journal of Psychology: Interdisciplinary and Applied, 148(1), 37-60. doi:10.1080/00223980.2012.742854 Poulin, M. J., Brown, S. L., Dillard, A. J., & Smith, D. M. (2013). Giving to Others and the Association Between Stress and Mortality. American Journal of Public Health, 103(9), 1649-1655. doi:10.2105/Ajph.2012.300876 Pressman, S. D., Kraft, T. L., & Cross, M. P. (2015). It’s good to do good and receive good: The impact of a ‘pay it forward’ style kindness intervention on giver and receiver well- being. The Journal of Positive Psychology, 10(4), 293-302. doi: 10.1080/17439760.2014.965269 Proctor, C., Maltby, J., & Linley, P. A. (2011). Strengths use as a predictor of well-being and health-related quality of life. Journal of Happiness Studies, 12(1), 153-169. doi:10.1007/ s10902-009-9181-2 Raposa, E. B., Laws, H. B., & Ansell, E. B. (2016). Prosocial Behavior Mitigates the Negative Effects of Stress in Everyday Life. Clinical psychological science : a journal of the Association for Psychological Science, 4(4), 691-698. doi: 10.1177/2167702615611073 Reyniers, D., & Bhalla, R. (2013). Reluctant altruism and peer pressure in charitable giving. Judgment and Decision Making, 8(1), 7-15. Rudd, M., Aaker, J., & Norton, M. I. (2014). Getting the most out of giving: Concretely framing a prosocial goal maximizes happiness. Journal of Experimental Social Psychology, 54, 11-24. doi:10.1016/j.jesp.2014.04.002 Schwartz, C. E., & Sendor, R. M. (1999). Helping others helps oneself: response shift effects in peer support. Social Science & Medicine, 48(11), 1563-1575. doi:10.1016/ s0277-9536(99)00049-0 Sin, N. L., & Lyubomirsky, S. (2009). Enhancing well-being and alleviating depressive symptoms with positive psychology interventions: a practice-friendly meta-analysis. Journal of Clinical Psychology, 65(5), 467-487. doi:10.1002/jclp.20593 *Trew, J. L., & Alden, L. E. (2015). Kindness reduces avoidance goals in socially anxious individuals. Motivation and Emotion, 39(6), 892-907. doi:10.1007/s11031-015-9499-5 Weinstein, N., DeHaan, C. R., & Ryan, R. M. (2010). Attributing autonomous versus introjected motivation to helpers and the recipient experience: Effects on gratitude, attitudes, and well-being. Motivation and Emotion, 34(4), 418-431. doi:10.1007/ s11031-010-9183-8 Weinstein, N., & Ryan, R. M. (2010). When helping helps: Autonomous motivation for prosocial behavior and its influence on well-being for the helper and recipient. Journal of Personality and Social Psychology, 98(2), 222-244. doi:10.1037/a0016984 Weiss, L. A., Westerhof, G. J., & Bohlmeijer, E. T. (2016). Can We Increase Psychological Well-Being? The Effects of Interventions on Psychological Well-Being: A Meta-Analysis of Randomized Controlled Trials. PLoS ONE, 11(6), e0158092. doi:10.1371/ journal.pone.0158092 *Whillans, A. V., Dunn, E. W., Sandstrom, G. M., Dickerson, S. S., & Madden, K. M. (2016). Is spending money on others good for your heart? Health Psychology, 35(6), 574-583. doi:10.1037/hea0000332
"37 Endnotes
1 Even then the effects are modest. This meta-analysis of the relationship between volunteering and health in the elderly found that volunteers were 22% less likely that non-volunteers to die during the follow-up period of the studies (Jenkinson, et al., 2013). However, the import of this finding depends on the base-rate. By way of illustration, if on average 10 out of 1000 (1%) non-volunteers die during the follow-up period, then a 22% percent decrease means that 7.8 out of 1000 (0.78%) volunteers would die during the same period. Moreover, as this review goes on to say: “These findings were not confirmed by experimental studies.”
2 The most highly cited paper in the kindness literature (with 597 citations at the time of the last search) purports to provide evidence that kind acts boosts the well-being of the actor (Sonja Lyubomirsky, Sheldon, & Schkade, 2005). However, the article does not report the size of the sample, the dependent measure, or any inferential statistics (for example, effect size or significance). Email correspondence with the author revealed that the data are no longer available.
3 4 Although see critical commentary, suggesting that this might be an over-estimate.
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