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Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor
Open accessAbstract
Do acts of kindness improve the well-being of the actor? 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. 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 identified 489 articles; of which 24 (27 studies) met the inclusion criteria (total N = 4045). These 27 studies, some of which included multiple control conditions and dependent measures, yielded 52 effect sizes. Multi-level modeling revealed that the overall effect of kindness on the well-being of the actor is small-to-medium (δ = 0.28). The effect was not moderated by sex, age, type of participant, intervention, control condition or outcome measure. There was no indication of publication bias. We discuss the limitations of the current literature, and recommend that future research test more specific theories of kindness: taking kindness-specific individual differences into account; distinguishing between the effects of kindness to specific categories of people; and considering a wider range of proximal and distal outcomes. Such research will advance our understanding of the causes and consequences of kindness, and help practitioners to maximise the effectiveness of kindness interventions to improve well-being.
Overview
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Written from the paper’s full text.
TL;DR
This systematic review and meta-analysis of experimental kindness interventions found that performing acts of kindness improves the actor’s subjective well-being, with a small-to-medium overall effect (δ = 0.28). Across 27 studies (N = 4045), effects were not moderated by tested demographic, intervention, control, or outcome variables, and there was no indication of publication bias.
Key findings
- The overall effect of kindness on actor well-being was δ = 0.28, 95% CI [0.16, 0.41], Z = 4.36, p < .001, described as approximately equivalent to a 0.6 increase on a standard 0–10 happiness scale.
- The review identified 24 articles containing 27 studies (total N = 4045) and 52 effect sizes; individual effect sizes ranged from −0.46 to 1.25 (M = 0.25, SD = 0.32), and sample sizes ranged from 26 to 474 (M = 158.57, SD = 132.05).
- The effect was not moderated by sex, age, type of participant, intervention, control condition, or outcome measure; metaforest screening yielded a median out-of-bootstrap explained variance of R²_oob = −0.11.
- There was no indication of publication bias: Begg’s test was Z = 1.07, p = .28, and file drawer analysis indicated 1919 unpublished null studies would be needed to bring the average unweighted effect to nonsignificance.
Methods
- Systematic searches of Web of Science and PsychInfo plus other sources yielded 489 articles after duplicate removal; 24 articles (27 studies) met inclusion criteria requiring experiments that randomly allocated participants to kind-behaviour interventions versus controls and subsequently measured well-being.
- Study characteristics were coded, including age, sex, location, participant type, intervention type, recipient type, control condition, dependent measures, group sizes, and Cohen’s d effect sizes; effect sizes were taken from papers or computed from reported statistics.
- Main analysis used three-level meta-analysis in R with metafor to account for dependent effect sizes within studies; metaforest random forests with 10,000 bootstrap samples were used to screen potential moderators.
Limitations
- The paper states that most reviewed studies were underpowered (average sample size per condition N = 79; power 1−β = 0.42 to detect d = 0.28; at least 202 per group needed for 1−β = 0.80), mostly used non-clinical student samples from W.E.I.R.D. societies, did not manipulate the motive behind kind acts, did not test fine-grained predictions from specific altruism theories or systematically vary recipient type, and mostly examined immediate rather than longer-term or distal outcomes.
- The text also makes evident that some effect sizes could not be calculated because statistics were not reported in the paper or available from the authors (Table 1 note), and that the small sample size limited moderator analysis, requiring metaforest to avoid overfitting.
- The paper notes that control conditions varied, and some studies compared kindness with doing nothing, which may confound kindness effects with the effects of performing any novel fun activity.
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In the paper
“Email correspondence with the author revealed that the data are no longer available.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
What the sources say
- Not checked yetcites Lyubomirsky, Sheldon, & Schkade, 2005 source
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIn the paper
“File drawer analysis (Rosenthal, 1979) revealed that 1919 unpublished, filed, or unretrieved studies averaging null results would be required to bring the average unweighted effect size to nonsignificance.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.3. Meta-analysis
What the sources say
- Not checked yetcites Rosenthal, 1979 source
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesA result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Multi-level modeling revealed that the overall effect of kindness on the well-being of the actor is small-tomedium (δ = 0.28).”
- Also stated in: § 5.3. Meta-analysis · plain
“Results revealed that the overall effect size estimate was δ = 0.28, 95% CI [0.16, 0.41], Z = 4.36, p < .001(see Fig. 2).This is a small-to-medium effect, approximately equivalent to an increase of 0.6 on a standard 0-10 happiness scale (Helliwell, Layard, & Sachs, 2016).”
- Also stated in: § 6. Discussion · hedged
“The results of this systematic review and meta-analysis of the experimental kindness literature suggests that performing acts of kindness improves the well-being of the actor (δ = 0.28).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes- Also stated in: § 5.3. Meta-analysis · plain
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Fourth, although the finding is consistent with the general evolutionary account of altruism outlined above, existing research has not tested the more fine-grained predictions that arise from the more specific theories of helping (kin altruism, mutualism, reciprocal altruism and competitive altruism).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIn the paper
“Second, most of the reviewed studies used non-clinical samples of students, from Western, Educated, Industrial, Rich, Democratic societies (W.E.I.R.D.; Henrich, Heine, & Norenzayan, 2010).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
What the sources say
- Not checked yetcites Henrich, Heine, & Norenzayan, 2010 source
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In the paper
“The effect size estimates ranged from -0.46 to 1.25 (M = 0.25, SD = 0.32).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.2. Descriptive statistics
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesA result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The recipients of kindness included colleagues and charities, but were for the most part left unspecified, and could be 'anyone'familiar or unfamiliar, family, friend, community member of stranger.”
- Also stated in: § 6. Discussion · plain
“In fact, in most cases the recipient was left unspecified that is, they could be 'anyone'.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.1. Study characteristics
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes- Also stated in: § 6. Discussion · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“There was no indication of publication bias.”
- Also stated in: § 5.3. Meta-analysis · hedged
“Begg's test of funnel asymmetry (based on random-effects meta-analysis) similarly did not indicate significant bias, Z = 1.07, p = 0.28.”
- Also stated in: § 6. Discussion · plain
“And there was no evidence of publication bias.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Strength:plain· not yet calibratedn = 4,045Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes- Also stated in: § 5.3. Meta-analysis · hedged
In the paper
“This is a small-to-medium effect, approximately equivalent to an increase of 0.6 on a standard 0-10 happiness scale (Helliwell, Layard, & Sachs, 2016).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.3. Meta-analysis
What the sources say
- Not checked yetcites Helliwell, Layard, & Sachs, 2016
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesWhat the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The small sample size limits our ability to include these moderators in mixed-effects meta-analysis without risking overfitting (modeling random noise in the data, rather than true moderating effects).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.4. Moderation
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- Probably not a substantial claim. 18
- It may state two separate claims as one. 18
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Three-level model | 3 | 22.14 28.16 -8.07 | | |”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Sample sizes ranged from 26 to 474 participants (M = 158.57,SD = 132.05).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.2. Descriptive statistics
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Likelihood ratio tests also indicated that constraining the within-studies variance to zero would not worsen model fit, whereas constraining either the between-studies variance or both variance components to zero did lead to significant deteriorations in model fit (see Table 2).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.3. Meta-analysis
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Fifth and finally, existing research has tended to look at the immediate effects of kindness well-being.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesProbably not a substantial claim.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The studies reviewed here varied whether actions benefitting others were performed, they did not vary whether the benefits were intended or notin other words, they did not manipulate the motive behind the action.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“First, most of the reviewed studies were under-powered.The average sample size per condition was N = 79; this gives power of only 1-β = 0.42 to detect a typical effect size of d = 0.28.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
Strength:plain· not yet calibratedn = 79Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The within-studies variance component σ w 2 was negligible, 0.00, 95% CI [ < 0.01, 0.02].The between-studies variance σ b 2 , on the other hand, differed significantly from zero, 0.08, 95% CI [0.04, 0.18].”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.3. Meta-analysis
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The median estimated explained variance in out-of-bootstrap cases was negative (R oob 2 = -0.11),with a large standard deviation across replications (SD = 0.19).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.4. Moderation
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Between-studies variance constrained | 2 | 33 | 36.76 -14.37 12.61 0 | |”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
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In the paper
“However, the article does not report the size of the sample, the dependent measure, or any inferential statistics (for example, effect size or significance).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
What the sources say
- Not checked yetcites Lyubomirsky, Sheldon, & Schkade, 2005 source
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The effect was not moderated by sex, age, type of participant, intervention, control condition or outcome measure.”
- Also stated in: § 5.4. Moderation · plain
“we did not find evidence for associations between the moderators and effect size.”
- Also stated in: § 6. Discussion · plain
“The effect was not moderated by sex, age, type of participant, intervention, control condition or outcome measure.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
- Also stated in: § 5.4. Moderation · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Our initial search of the literature identified 489 articles; of which 24 (27 studies) met the inclusion criteria (total N = 4045).”
- Also stated in: § 5.1. Study characteristics · plain
“These 27 studies included a total of 4045 participants (mean proportion male = 35%, mean age = 25.04,SD = 11.05).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
- Also stated in: § 5.1. Study characteristics · plain
In the paper
“The most highly cited paper in the kindness literature (with citations at the time of the last search) purports to provide evidence that kind acts boosts the well-being of the actor(Lyubomirsky, Sheldon, & Schkade, 2005).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
What the sources say
- Not checked yetcites Lyubomirsky, Sheldon, & Schkade, 2005 source
Strength:hedged· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“These 27 studies, some of which included multiple control conditions and dependent measures, yielded 52 effect sizes.”
- Also stated in: § 5.1. Study characteristics · plain
“Some studies had multiple control conditions, and/or multiple outcome measures, and hence provided more than one effect size; there were 52 in total.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Strength:plain· not yet calibratedn = 4,045Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
- Also stated in: § 5.1. Study characteristics · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Within-studies variance constrained | 2 | 20.14 24.15 -8.07 | 0 | 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 ☆ > 7. Conclusion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Both variance components constrained 1 | 78 | 80.25 -38.12 60.1 | 0 | |”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“In order to detect such an effect with power 1-β = 0.80, future researchers should use a sample size of at least 202 per group (Faul, Erdfelder, Lang, & Buchner, 2007).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
What the sources say
- Not checked yetcites Faul, Erdfelder, Lang, & Buchner, 2007 source
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“These theories predict that people will be 'happy to help' family, friends, community members, spouses, and even strangers under some conditions.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Abstract
Strength:plain· not yet calibratedCausal:conditional· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✗ Based: failsProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“We replicated the analysis 100 times to ensure the reliability of findings.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.4. Moderation
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Thus it remains unclear whether the current findings would generalise to clinical samples of participants diagnosed with specific mental health problems, in non-WEIRD societies.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
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In the paper
“The data and analysis script for this study are available on its Open Science Framework page (https://osf.io/sey6x/).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > Additional information
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Together, these results suggest that policy-makers and practitioners are correct to see kindness interventions as effective ways of improving wellbeing.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“These averages are approximate (~), because the age and sex ratio of the samples were not available for some studies.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Helping others makes you happy, but the effect is relatively modest.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The fact that the between-studies component was larger than the within-studies component indicates that the variation in effect sizes was primarily accounted for by differences between studies, whereas differences between effect sizes within the same studies were negligible.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 5.3. Meta-analysis
Strength:hedged· not yet calibratedCausal:correlational· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
In the paper
“Previous research has found an association between motive and outcome; one longitudinal study found that volunteers motivated by a desire to help others lived longer than non-volunteers, but that volunteers motivated by a desire to help themselves did not (Konrath, Fuhrel-Forbis, Lou, & Brown, 2012).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
What the sources say
- Not checked yetcites Konrath, Fuhrel-Forbis, Lou, & Brown, 2012
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Note that the argument here is that biology and culture have equipped us to help automatically, intuitively, innocentlythere is no suggestion that people are necessarily aware of the causes of their benevolent behaviour, or are acting from any ulterior motive.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✗ Checkable: fails✗ Load-bearing: fails✗ Based: failsProbably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. The paper may give no reason why it holds. It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“The effect of kindness is small-to-mediumcomparable to other positive psychology interventions (such as 'mindfulness', 'positive thinking' and 'counting your blessings'; d = 0.34, Bolier et al., 2013;d = 0.31, Sin & Lyubomirsky, 2009;d = 0.44, Weiss, Westerhof, & Bohlmeijer, 2016).”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
What the sources say
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“And they support the general claim that, as social animals, humans possess a range of psychological mechanisms that motivate them to help others, and that they derive satisfaction from doing so.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 6. Discussion
Strength:plain· not yet calibratedCausal:correlational· not yet calibratedTests✓ Asserted: passes✗ Checkable: fails✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“*= Statistics neededto calculate effect size were not reported in the paper, nor available from the authors.”
§ Happy to help? A systematic review and meta-analysis of the effects of performing acts of kindness on the well-being of the actor ☆ > 7. Conclusion
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
The paper relies on this without support.
The experimental studies included in the meta-analysis validly manipulated kindness and measured well-being, so their effect sizes can be interpreted as causal.
“experiments that randomly allocated participants to (b) interventions involving kind behaviour and controls and (c) subsequently measured and compared participant well-being.”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“Altruistic and prosocial social behavior appears to promote well-being for the helpers [18, 39].”
From Psychiatric symptoms, risk, and protective factors among university students in quarantine during the COVID-19 pandemic in China (2021) · cites this paper as [18]
In the citing paper
“Prosocial behavior has been associated with a plethora of positive mental health outcomes, including increased positive affect, family and community impact, social network, overall mental health, and satisfaction with life, as reviewed by Curry et al. ( 2018 ).”
From A latent profile analysis of aggression and prosocial behavior in relation to adolescent wellbeing (2025) · cites this paper as Curry et al., 2018
In the citing paper
“a meta-analysis of 27 experimental studies shows that practising acts of kindness has a small-to-moderate effect on increasing well-being of the kindness-actors 5 .”
From Kindness as a public health action (2025) · cites this paper as [5]
Statistics recomputed
Every reported test result, recomputed from its test statistic and degrees of freedom. A result shows as not adding up only once an independent check has confirmed it.
- Consistentz = 4.36reported p < .001 · recomputed p < .001
“Z = 4.36, p < .001”
- Consistentz = 1.07reported p = .28 · recomputed p = .285
“Z = 1.07, p = .28”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Self-check results appear here once an independent check has confirmed them.
Citations
Cites
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Watson, D., Clark, L. A., & Tellegen, A. (1988) · Journal of Personality and Social Psychology · doi:10.1037/0022-3514.54.6.1063 · Cited by 32,433
The satisfaction with life scale
Diener, E., Emmons, R. A., Larsen, R. J., & Griffin, S. (1985) · Journal of Personality Assessment · doi:10.1207/s15327752jpa4901_13 · Cited by 31,768
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Viechtbauer, W. (2010) · Journal of Statistical Software · doi:10.18637/jss.v036.i03 · Cited by 20,464
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On Happiness and Human Potentials: A Review of Research on Hedonic and Eudaimonic Well-Being
Ryan, R. M., & Deci, E. L. (2001) · Annual Review of Psychology · doi:10.1146/annurev.psych.52.1.141 · Cited by 11,567
The Evolution of Reciprocal Altruism
Trivers, R. L. (1971) · The Quarterly Review of Biology · doi:10.1086/406755 · Cited by 11,010
The file drawer problem and tolerance for null results.
Rosenthal, R. (1979) · Psychological Bulletin · doi:10.1037/0033-2909.86.3.638 · Cited by 9,068 · cited 1×
“File drawer analysis (Rosenthal, 1979) revealed that 1919 un-published, fi led, or unretrieved studies averaging null results would be required to bring the average unweighted e ff ect size to nonsigni fi cance.”
Flagged first, then by citations
Research works printed but not linked: 1
- Gardner, 2014, Special issue: Inclusive fitness; 50 years on, Philosophical Transactions of the Royal Society, B: Biological Sciences, 369
Cited by
Sorted by citations
Effectiveness of positive psychology interventions: a systematic review and meta-analysis
Carr, A., Cullen, K., Keeney, C., Canning, C., Mooney, O., Chinseallaigh, E., & O’Dowd, A. (2021) · The Journal of Positive Psychology · doi:10.1080/17439760.2020.1818807 · Cited by 645
Aknin, L. B., De Neve, J.-E., Dunn, E. W., Fancourt, D. E., Goldberg, E., Helliwell, J. F., Jones, S. P., Karam, E., Layard, R., Lyubomirsky, S., et al. (2022) · Perspectives on Psychological Science · doi:10.1177/17456916211029964 · Cited by 418
Rewards of kindness? A meta-analysis of the link between prosociality and well-being.
Hui, B. P. H., Ng, J. C. K., Berzaghi, E., Cunningham-Amos, L. A., & Kogan, A. (2020) · Psychological Bulletin · doi:10.1037/bul0000298 · Cited by 430
Sun, S., Goldberg, S. B., Lin, D., Qiao, S., & Operario, D. (2021) · Globalization and Health · doi:10.1186/s12992-021-00663-x · Cited by 221
Fernández‐Castilla, B., Jamshidi, L., Declercq, L., Beretvas, S. N., Onghena, P., & Noortgate, W. V. D. (2020) · Behavior Research Methods · doi:10.3758/s13428-020-01373-9 · Cited by 195
Metadata
- Authors
- Curry, O. S., Rowland, L. A., Van Lissa, C. J., Zlotowitz, S., McAlaney, J., & Whitehouse, H.
- Affiliations
- University of Oxford (GB)
- University College London (GB)
- Bournemouth University (GB)
- Corresponding author
- Curry, Oliver Scott
- Venue
- Journal of Experimental Social Psychology
- Publisher
- Elsevier BV
- Published
- 2018-05
- Volume
- 76
- Pages
- 320-329
- ISSN
- 0022-1031 (ISSN-L)
- OpenAlex
- W2776060271
- Cited by
- 528
- References
- 143
- Citations by year
- 2026: 66 · 2025: 80 · 2024: 92 · 2023: 72 · 2022: 93 · 2021: 75 · 2020: 29 · 2019: 15 · 2018: 5
- FWCI
- 4.81
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Journal of Experimental Social Psychology (publishedVersion, cc-by-nc-nd)
- Bournemouth University Research Online (Bournemouth University) (acceptedVersion)
- Utrecht University Repository (Utrecht University) (submittedVersion, other-oa)
- Funders
- kindness.org (R46536/CN001)
- Topics
- Social Sciences › Psychology › Social Psychology › Psychological Well-being and Life Satisfaction
- Social Sciences › Sociology and Political Science › Nonprofit Sector and Volunteering
- Social Sciences › Psychology › Clinical Psychology › Mindfulness and Compassion Interventions
- Keywords
- acts of kindness, random acts of kindness, subjective well-being, altruism, prosocial behavior, happiness, individual differences
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-06, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-06 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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