The Kindness Revolution: 3 students, 1 mission.

Introduction

The term "subjective well-being" (SWB) describes how individuals think about and evaluate their life. It is well documented in the literature that subjective well-being is positively related to income (Kahneman & Deaton, 2010; Lindqvist et al., 2020; Stevenson & Wolfers, 2013). Even so, certain research has revealed weaknesses in this established association. For example, Jebb et al. (2018) have identified income thresholds for subjective well-being- specifically life evaluation, positive affect, and negative affect; beyond which higher incomes no longer increase well-being. For example, the life evaluation threshold ranged from $40,000 in some regions to $105,000 in others. It also depends on where your income is moving up from, where Diener and Biswas-Diener (2002) found that increasing income is unlikely to significantly improve subjective wellbeing for middle-class and upper-class individuals in economically developed countries. Not to mention, people's aspirations tend to increase in tandem with increases in their income (Binswanger, 2006), creating a discrepancy, called the ‘hedonic treadmill’ (Brickman, 1971). This can eventually cause happiness to stagnate. 

There are other ways to improve the SWB of individuals. For example, humans are able to derive emotional benefits from simply spending money on others. This type of behaviour is called prosocial spending. When participants chose the option to donate money as well as to recall instances when they had spent money on others, Aknin et al. (2013) found participants reporting greater levels of happiness than when they spent money on themselves. This effect was observed in nations with varying economic climates and cultural backgrounds. According to Hill & Howell (2014), the primary reason behind this effect is concern for others rather than a lack of concern for oneself. Akinin et al (2013) concluded that this helping behaviour effect was a psychological universal. The rest of the research base certainly supports this assertion, where improvements in the SWB of adults and adolescents due to prosocial activity has been found both at the between-person level, which describes when we compare prosocial conduct across individuals, (Aknin et al., 2020; Titova & Sheldon, 2021) and at the within-person level (Gregori et al, 2024), describing when individuals increase their level of prosocial behaviour beyond their typical conduct.

There have been many explanations as to why this effect is observed. From an evolutionary standpoint, the emotional benefit from helping others might have evolved as a mechanism to promote greater prosociality. Although this kind of behaviour could have short-term consequences, it would on the whole, benefit our long-term survival (Akin et al, 2013). This would be through helping the greater good of the group and increasing the likelihood of reciprocal kindness (Curry et al., 2018). Chen (2024) in a systematic review, proposed that prosocial behaviour improved SWB because it satisfied one or more of our basic psychological needs (autonomy, competence and relatedness). For example, prosocial conduct satisfies our competence needs when people are aware of the beneficial impact their helpful behaviour has on the recipient. 

Have non-monetary prosocial behaviours been shown to have the same positive impact on SWB? Most of the research in this area has examined whether formal volunteering can enhance our SWB (Tabassum et al., 2016). In particular, the positive impact this type of prosocial activity has on the SWB of older individuals (Jiang et al., 2018). Nevertheless, sporadic research has been conducted with younger populations. For example, Kim and Morgül (2017) found an association between youth volunteering and psychological well-being in adulthood. Moreover, Layous et al. (2012) found significant improvements to life satisfaction, happiness and positive affect in schoolchildren when they engaged in acts of kindness. However, there is discussion over whether this prosociality benefit can be attributed to social connectedness. That being said, Martela and Ryan (2016) discovered that even in the absence of face-to-face connection, benevolent acts can still improve well-being. In addition, Miles et al. (2022) found small, lasting benefits to emotional wellbeing when participants performed 3 acts of prosociality a week amidst the COVID-19 pandemic. 

In this project, we drew upon research conducted by Lyubomirsky and colleagues (2004). Over six weeks, college students completed five acts of kindness per week as part of a happiness-based intervention. Other condition groups included students who completed no acts of kindness and students who completed all of their acts of kindness for a week in a single day. Our project's research question was whether engaging in a variety of prosocial activities would result in similar observed improvements to SWB. Our time scale was set at 2 weeks, with 14 total acts of kindness performed in both experimental conditions. The intent behind the reduced time scale was to determine whether the effect on SWB might still be acquired after only a short period of prosocial involvement. Research suggests that the benefit of prosocial activity on wellbeing, specifically formal volunteering, could plateau if overdone (Yang, 2020). 

Each condition was completed by a single individual under the age of 25. Currently there is a lack of research investigating the benefit prosociality, particularly volunteering, has on the wellbeing of young adult populations (Stuart et al., 2020). We were able to contribute to this gap in the literature. Three measures of subjective wellbeing—positive and negative affect, life satisfaction, and subjective happiness—were measured to gauge each person's level of SWB. We predicted that across all three measures of SWB , each participant's scores would be greater in the 2 prosociality conditions, compared to the control (Hypothesis 1). We also predicted that wellbeing scores would be greater in the 7 acts of kindness in one day condition compared to the 1 acts of kindness each day condition (Hypothesis 2). This was predicted due to the findings from Lyubomirksy et al. (2004), who discovered that participants' wellbeing only improved when they completed all of their weekly acts of kindness in a single day. 

Method

Our study followed a self-experimental, mixed design in which three of us researchers acted as experimenters and participants. Each participant completed one of the three study conditions over two weeks. The intervention conditions were modelled on the study conducted by Lyubomirsky et al. (2004), with our primary modification being a condensed duration and an altered structure of the kindness acts.

Each of the three researchers were randomly selected into one of the following groups: the first condition involved performing one act of kindness each day for 14 consecutive days; the second condition required the participant to carry out all 14 acts of kindness over two days (e.g., seven acts each day, spaced one week apart); the third condition functioned as a control, with the participant continuing their routine without any instructed prosocial behaviour. All three participants completed the same three validated measures of SWB at four different time points: prior to the intervention (pre-week 1), after the first week (post-week 1), at the beginning of the second week (pre-week 2), and after the study (post-week 2). These measures were selected to provide a multi-dimensional view of subjective well-being, assessing emotional and cognitive components.

Positive and negative affect were measured using the Positive and Negative Affect Schedule (PANAS; Watson et al., 1988), which includes 20 adjectives rated on a 5-point Likert scale according to how strongly they are felt "at this moment." Scores for the 10 positive and 10 negative items are summed separately, producing a possible range of 10–50 for each dimension. The Satisfaction With Life Scale (SWLS; Diener et al., 1985) was used to measure cognitive evaluations of one's life. It consists of five statements rated on a 7-point scale (1 = strongly disagree to 7 = strongly agree), yielding a score between 5 and 35, with higher scores indicating greater life satisfaction. Subjective happiness was assessed using the Subjective Happiness Scale (SHS; Lyubomirsky & Lepper, 1999), which contains four items evaluated on a 7-point scale. One item is reverse scored before the mean of the four items is calculated, resulting in a total score ranging from 1 to 7, with higher values indicating greater happiness. 

Each participant completed the questionnaires individually and privately. Those in the intervention groups were encouraged to carry out their acts of kindness as naturally as possible, without documenting or reflecting formally on their experiences in order to minimise demand characteristics and preserve the intervention's ecological validity. All acts were self-initiated and consistent with the examples provided in previous research. For example, some of the acts of kindness performed in both experimental conditions included donating blood, baking a cake for someone, donating clothes to charity, volunteering as a park run marshall, hugging a stranger, leaving kind notes in public places, giving a lift home to a work colleague, and paying for a little kid’s Easter egg after seeing him cry when his mum kept saying no.

 Results 

Overall, the results revealed a promising improvement in SWB across both prosocial conditions, with some positive change also noted in the control condition. The two-day kindness condition consistently showed the most improvement across all three well-being measures, aligning with previous findings that condensed prosocial activity may generate a more substantial psychological impact (Lyubomirksy et al., 2004). This shows the potential of prosocial behaviour to enhance SWB significantly.

Regarding positive affect, the participant in the one-a-day kindness condition experienced a steady increase from a baseline score of 25 to 34 by the end of week two. The participant in the two-day condition demonstrated a sharper rise, from 26 to 36 by the end of week one, followed by a temporary drop to 12 before recovering to 32 by post-week two. The control condition also improved, with positive affect scores increasing from 25 to 33. This suggests that external factors, such as improved weather or personal life events, may have contributed to elevated mood during the intervention and increased the scores. While negative affect remained low across conditions, fluctuations were present nonetheless, highlighting the importance of individual and contextual factors in influencing well-being.

                   

                                                                    

Life satisfaction scores (SWLS) revealed a stronger contrast between conditions. The two-day kindness participant showed the most significant gain in SWLS scores, rising from 16 at baseline to 28 at post-week two. The control participant also improved notably, from 20 to 29, while the one-a-day participant experienced a slight decline, from 22 to 20. This suggests that although daily acts of kindness may improve emotional affect, their impact on cognitive life evaluation may take longer to see significant differences or require more reflective processing.

Subjective happiness (SH) scores followed a similar trend. The one-a-day participant’s score increased modestly from 5.0 to 5.5, while the two-day participant showed the most significant improvement from 4.75 to 6.5. Interestingly, the control participant’s happiness also rose substantially, from a low baseline of 3.0 to 5.75 by the end of the intervention period. These findings highlight the complexity of subjective well-being, as we can see improvements can occur through intentional behaviour or even through unmeasured life events or internal shifts.

Discussion 

This project set out to explore whether engaging in non-monetary prosocial behaviour over a short period of time could meaningfully improve SWB in young adults. Drawing on the experimental design of Lyubomirsky et al. (2004), we implemented two prosocial conditions, one involving 14 acts of kindness distributed daily across two weeks, and another condensing the same number of acts into just two specific days (once per week). A third condition served as the control, where no acts of kindness were performed. To evaluate changes in well-being, we used three validated measures: the PANAS to assess emotional affect (Watson et al., 1988), the Satisfaction With Life Scale (SWLS; Diener et al., 1985), and the Subjective Happiness Scale (SHS; Lyubomirsky & Lepper, 1999).

Our findings were in line with what was predicted in Hypothesis 1, where participants in both prosocial conditions experienced improvements in overall SWB by the end of the two-week intervention. Positive affect scores increased, life satisfaction rose, and participants reported feeling generally happier. Although all three participants were young adults under the age of 25 and engaged in different kindness schedules, the emotional and cognitive gains were consistent with the existing body of literature, suggesting that helping others, whether briefly or consistently, yields tangible emotional benefits (Aknin et al., 2013; Layous et al., 2012). Interestingly, a slight advantage appeared for the one-day-per-week kindness condition, supporting hypothesis 2 and aligning with the Lyubomirsky et al. (2004) finding that grouping acts together may create a more noticeable and memorable psychological impact.

These results align with a growing body of evidence suggesting that acts of kindness improve well-being not just because of what is done, but because of how they fulfil certain human needs. Self-determination theory (Deci & Ryan, 2000) provides a useful lens for understanding this effect. According to the theory, behaviours that satisfy psychological needs such as competence, autonomy, and relatedness are more likely to enhance well-being. When individuals perform acts of kindness, they may feel more socially connected, more capable of making a difference, and more in control of their actions, all of which contribute to elevated happiness. The universality of this finding is particularly compelling: prosocial behaviour has been shown to benefit individuals across cultures, age groups, and income levels (Aknin et al., 2020), reinforcing its robustness as a pathway to improved mental health and greater life satisfaction. In the context of our study, these theoretical perspectives help explain why even a relatively short intervention period was sufficient to generate positive changes. Participants didn’t need to spend money, volunteer extensively, or engage in complex activities—simply performing intentional, thoughtful acts of kindness was enough to foster meaningful shifts in how they felt and evaluated their lives.

While the findings offer promising insights, several limitations must be acknowledged. The most significant is the extremely small sample size; just one participant per condition means the results are illustrative rather than conclusive. With such a limited number of data points, it is difficult to draw strong generalisations or run meaningful statistical analyses. Additionally, the study relied on self-report measures, which, while widely validated, are still vulnerable to subjective biases such as social desirability or mood fluctuations unrelated to the intervention. The short duration of the project (two weeks) may also have constrained the potential for long-term or sustained well-being changes to emerge. In contrast, many existing interventions, such as those discussed in Lyubomirsky et al. (2005) and Sheldon and Lyubomirsky (2006), spanned six weeks or more. A longer timeframe may allow for deeper internalization of the benefits of prosocial behaviour and offer a clearer understanding of whether those benefits plateau, persist, or fade over time (Lyubomirsky et al., 2011). It is also important to consider the broader context: this study took place during a time when students were likely under academic pressure and approaching a holiday break. Factors such as coursework deadlines, personal stress, or even the positive anticipation of Easter could have independently influenced participants' well-being scores. Because these external variables were not controlled for, they represent potential confounds that could have skewed the results.

To build on these initial insights, future research should aim for greater scale and rigour. Larger, randomised samples would allow researchers to draw firmer conclusions and examine whether the effects of prosocial behaviour vary by personality, socioeconomic status, or baseline SWB. Future studies might also benefit from incorporating qualitative methods, such as reflective journaling or post-intervention interviews, to better understand how participants experience and make meaning from their kind acts. This could shed light on whether it is the act itself, the intention behind it, or the response it receives that contributes most to well-being. It would also be valuable to test the effects of different types of prosocial behaviour, particularly comparing monetary and non-monetary acts, or visible versus anonymous gestures, to explore which are most impactful. Curry et al. (2018) highlighted that while acts of kindness generally enhance SWB, future research should investigate how different forms of kindness, such as those directed toward friends versus strangers, might vary in their emotional benefits. Furthermore, future interventions could manipulate the degree of personal connection involved in kindness, such as helping friends versus strangers, to assess whether social closeness moderates the emotional outcomes.

Overall, while this project was small in scale, it contributes meaningfully to the growing evidence base on kindness and SWB. It offers a simple but powerful takeaway: even short-term, intentional efforts to be kind, regardless of their format, have the potential to create real emotional benefits.

References

Aknin, L. B., Barrington-Leigh, C. P., Dunn, E. W., Helliwell, J. F., Burns, J., Biswas-Diener, R., Kemeza, I., Nyende, P., Ashton-James, C. E., & 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. https://doi.org/10.1037/a0031578

Aknin, L. B., Dunn, E. W., Proulx, J., Lok, I., & Norton, M. I. (2020). Does spending money on others promote happiness?: A registered replication report. Journal of Personality and Social Psychology, 119(2), e15–e26. https://doi.org/10.1037/pspa0000191 

Binswanger, M. (2006b). Why does income growth fail to make us happier? The Journal of Socio-Economics, 35(2), 366–381. https://doi.org/10.1016/j.socec.2005.11.040

Brickman, P. (1971). Hedonic relativism and planning the good society. Adaptation level theory, 287-301.

Chen, Y. (2024). Prosocial Behavior and Well-Being: An Empirical review of the role of Basic Psychological Need satisfaction. The Journal of Psychology, 158(5), 325–346. https://doi.org/10.1080/00223980.2024.2307377 

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. https://doi.org/10.1016/j.jesp.2018.02.014

Deci, E. L., & Ryan, R. M. (2000). The "what" and "why" of goal pursuits: Human needs and the self-determination of behavior. Psychological Inquiry, 11(4), 227–268. https://doi.org/10.1207/S15327965PLI1104_01

Diener, E., Emmons, R. A., Larsen, R. J., & Griffin, S. (1985). The Satisfaction With Life Scale. Journal of Personality Assessment, 49(1), 71–75. https://doi.org/10.1207/s15327752jpa4901_13

Diener, E., & Biswas-Diener, R. (2002). Will money increase subjective well-being? Social Indicators Research, 57(2), 119–169. https://doi.org/10.1023/A:1014411319119

Gregori, F., López‐Pérez, B., Manfredi, L., Eisenberg, N., Lundie, D., Lee, S., Gerbino, M., Pastorelli, C., & Zuffianò, A. (2024). The relations among prosocial behavior, hedonic, and eudaimonic well‐being in everyday life. Journal of Personality. https://doi.org/10.1111/jopy.12937 

Hill, G., & Howell, R. T. (2014). Moderators and mediators of pro-social spending and well-being: The influence of values and psychological need satisfaction. Personality and Individual Differences, 69, 69–74. https://doi.org/10.1016/j.paid.2014.05.013

Jebb, A. T., Tay, L., Diener, E., & Oishi, S. (2018). Happiness, income satiation and turning points around the world. Nature Human Behaviour, 2(1), 33–38. https://doi.org/10.1038/s41562-017-0277-0 

Jiang, D., Hosking, D., Burns, R., & Anstey, K. J. (2018). Volunteering benefits life satisfaction over 4 years: The moderating role of social network size. Australian Journal of Psychology, 71(2), 183–192. https://doi.org/10.1111/ajpy.12217

Kahneman, D., & Deaton, A. (2010). High income improves evaluation of life but not emotional well-being. Proceedings of the National Academy of Sciences, 107(38), 16489–16493. https://doi.org/10.1073/pnas.1011492107

Kim, J., & Morgül, K. (2017). Long-term consequences of youth volunteering: Voluntary versus involuntary service. Social Science Research, 67, 160–175. https://doi.org/10.1016/j.ssresearch.2017.05.002 

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), e51380. https://doi.org/10.1371/journal.pone.0051380

Lindqvist, E., Östling, R., & Cesarini, D. (2020). Long-Run Effects of Lottery Wealth on Psychological Well-Being. The Review of Economic Studies, 87(6), 2703–2726. https://doi.org/10.1093/restud/rdaa006

Lyubomirsky, S., Dickerhoof, R., Boehm, J. K., & Sheldon, K. M. (2011). Becoming happier takes both a will and a proper way: An experimental longitudinal intervention to boost well-being. Emotion, 11(2), 391–402. https://doi.org/10.1037/a0022575

Lyubomirsky, S., Lepper, H. S. (1999). A measure of subjective happiness: Preliminary reliability and construct validation. Social Indicators Research, 46(2), 137–155. https://doi.org/10.1023/A:1006824100041

Lyubomirsky, S., Tkach, C., & Sheldon, K. M. (2004). [Pursuing sustained happiness through random acts of kindness and counting one's blessings: Tests of two six-week interventions]. Unpublished raw data. 

Lyubomirsky, S., Sheldon, K. M., & Schkade, D. (2005). Pursuing happiness: The architecture of sustainable change. Review of General Psychology, 9(2), 111–131. https://doi.org/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. https://doi.org/10.1007/s11031-016-9552-z

Miles, A., Andiappan, M., Upenieks, L., & Orfanidis, C. (2022). Using prosocial behavior to safeguard mental health and foster emotional well-being during the COVID-19 pandemic: A registered report of a randomized trial. PLoS ONE, 17(7), e0272152. https://doi.org/10.1371/journal.pone.0272152 

Stevenson, B., & Wolfers, J. (2013). Subjective Well-Being and Income: Is there any evidence of satiation? American Economic Review, 103(3), 598–604. https://doi.org/10.1257/aer.103.3.598  

Stuart, J., Kamerade, D., Connolly, S., Ellis Paine, A., Nichols, G., & Grotz, J. (2020). The impacts of volunteering on the subjective wellbeing of volunteers: A rapid evidence assessment. What Works Wellbeing. 

Titova, L., & Sheldon, K. M. (2021). Happiness comes from trying to make others feel good, rather than oneself. The Journal of Positive Psychology, 17(3), 341–355. https://doi.org/10.1080/17439760.2021.1897867 

Watson, D., Clark, L. A., & Tellegen, A. (1988). Development and validation of brief measures of positive and negative affect: The PANAS scales. Journal of Personality and Social Psychology, 54(6), 1063–1070. https://doi.org/10.1037/0022-3514.54.6.1063

Yang, J. (2020). Formal Volunteering Buffers the Negative Impact of Unemployment among Older Workers: A Longitudinal Analysis. Journal of Gerontological Social Work, 63(3), 189–208. https://doi.org/10.1080/01634372.2020.1744057