Cited by 528Psychological Well-being and Life SatisfactionNonprofit Sector and VolunteeringMindfulness and Compassion Interventions

The DOI matches its Crossref record; 143 of the 143 references it cites were found in a registry or an index; none of the 15 sources its claims cite is checked for support yet.

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 access
Curry, Oliver Scott, Rowland, Lee A., Van Lissa, Caspar J., Zlotowitz, Sally, McAlaney, John, Whitehouse, Harvey·2018·Journal of Experimental Social Psychology

Abstract

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

AI snapshot

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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Integrity signals

Registry

Crossref · 10.1016/j.jesp.2018.02.014

Cites

143 of 143 references verified0 citation errors · 0 not checkable

Statistics

Verification

Claims the paper makes

0 of 15 cited sources checked · 0 supported · 0 flagged

Show all 13 claims

  • Probably not a substantial claim. 18
  • It may state two separate claims as one. 18
30 of 30
  • 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.”
1 of 1

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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”

2 of 2

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Citations

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Research works printed but not linked: 1

  1. Gardner, 2014, Special issue: Inclusive fitness; 50 years on, Philosophical Transactions of the Royal Society, B: Biological Sciences, 369

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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
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

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