The study “Kindness Counts: Prompting Prosocial Behavior in Preadolescents Boosts Peer Acceptance and Well-Being” published by Layous and colleagues in the journal PLOS One on December 26, 2012 was cited by multiple websites as proof of how important it is to teach children to be kind. NPR commented on the study in the blog post “Random Acts Of Kindness Can Make Kids More Popular“, and the study was also discussed in ScienceDaily in “Kindness Key to Happiness and Acceptance for Children“, Fox News in “No bullies: Kind kids are most popular” and the Huffington Post in “Kind Kids Are Happier And More Popular (STUDY)“.

According to most of these news reports, the design of the study was rather straightforward. Schoolchildren ages 9 to 11 in a Vancouver school district were randomly assigned to two groups for a four week intervention: Half of the children were asked to perform kind acts, while the other half were asked to keep track of pleasant places they visited. Happiness and acceptance by their peers was assessed at the beginning and the end of the four week intervention period. The children were allowed to choose the “acts of kindness” or the “pleasant places”. The “acts of kindness” group chose acts such as sharing their lunch or giving their mothers a hug. The “pleasant places” group chose to visit places such as the playground or a grandparent’s house.

At the end of the four week intervention, both groups of children showed increased signs of happiness, but the news reports differed in terms of the impact of the intervention on the acceptance of the children.

The NPR blog reported:

… the children who performed acts of kindness were much more likely to be accepting of their peers, naming more classmates as children they’d like to spend time with.

This would mean that the children performing the “acts of kindness” were the ones that became more accepting of others.

The conclusion in the Huffington Post was quite different:

The students were asked to report how happy they were and identify classmates they would like to work with in school activities. After four weeks, both groups said they were happier, but the kids who had performed acts of kindness reported experiencing greater acceptance from their peers – they were chosen most often by other students as children the other students wanted to work with.

The Huffington Post interpretation (a re-post from Livescience) was that the children performing the “acts of kindness” became more accepted by others, i.e. more popular.

Which of the two interpretations was the correct one? Furthermore, how significant were the improvements in happiness and acceptance?

I decided to read the original PLOS One paper and I was quite surprised by what I found:

The manuscript (in its published form, as of December 27, 2012) had no figures and no tables in the “Results” section. The entire “Results” section consisted of just two short paragraphs. The first paragraph described the affect and happiness scores:

Consistent with previous research, overall, students in both the kindness and whereabouts groups showed significant increases in positive affect (γ00 = 0.15, S.E. = 0.04, t(17) = 3.66, p<.001) and marginally significant increases in life satisfaction (γ00 = 0.09, S.E. = 0.05, t(17) = 1.73, p = .08) and happiness (γ00 = 0.11, S.E. = 0.08, t(17) = 1.50, p = .13). No significant differences were detected between the kindness and whereabouts groups on any of these variables (all ps>.18). Results of t-tests mirrored these analyses, with both groups independently demonstrating increases in positive affect, happiness, and life satisfaction (all ts>1.67, all ps<.10).

There are no actual values given, so it is difficult to know how big the changes are. If a starting score is 15, then a change of 1.5 is only a 10% change. On the other hand, if the starting score is 3, then a change of 1.5 represents a 50% change. The Methods section of the paper also does not describe the statistics employed to analyze the data. Just relying on arbitrary p-value thresholds is problematic, but if one were to use the infamous p-value threshold of 0.05 for significance, one can assume that there was a significant change in the affect or mood of children (p-value <0.001), a marginally significant trend of increased life satisfaction (p-value of 0.08) and no really significant change in happiness (p-value of 0.13).

It is surprising that the authors do not show the actual scores for each of the two groups. After all, one of the goals of the study was to test whether performing “acts of kindness” has a bigger impact on happiness and acceptance than the visiting “pleasant places” (“whereabouts” group). There is a generic statement “ No significant differences were detected between the kindness and whereabouts groups on any of these variables (all ps>.18).”, but what were the actual happiness and satisfaction scores for each of the groups? The next sentence is also cryptic: “Results of t-tests mirrored these analyses, with both groups independently demonstrating increases in positive affect, happiness, and life satisfaction (all ts>1.67, all ps<.10).” Does this mean that p<0.1 was the threshold of significance? Do these p-values refer to the post-intervention versus pre-intervention analysis for each tested variable in each of the two groups? If yes, why not show the actual data for both groups?

The second (and final) paragraph of the Results section described acceptance of the children by their peers. Children were asked who they would like to “would like to be in school activities [i.e., spend time] with’’:

All students increased in the raw number of peer nominations they received from classmates (γ00 = 0.68, S.E. = 0.27, t(17) = 2.37, p = .02), but those who performed kind acts (M = +1.57; SD = 1.90) increased significantly more than those who visited places (M = +0.71; SD = 2.17), γ01 = 0.83, S.E. = 0.39, t(17) = 2.10, p = .05, gaining an average of 1.5 friends. The model excluded a nonsignificant term controlling for classroom size (p = .12), which did not affect the significance of the kindness term. The effects of changes in life satisfaction, happiness, and positive affect on peer acceptance were tested in subsequent models and all found to be nonsignificant (all ps>.54). When controlling for changes in well-being, the effect of the kindness condition on peer acceptance remained significant. Hence, changes in well-being did not predict changes in peer acceptance, and the effect of performing acts of kindness on peer acceptance was over and above the effect of changes in well-being.

This is again just a summary of the data, and not the actual data itself. Going to “pleasant places” increased the average number of “friends” (I am not sure I would use “friend” to describe someone who nominates me as a potential partner in a school activity) by 0.71, performing “acts of kindness” increased the average number of friends by 1.57. It did answer the question that was raised by the conflicting news reports. According to the presented data, the “acts of kindness” kids were more accepted by others and there was no data on whether they also became more accepting of others. I then looked at the Methods section to understand the statistics and models used for the analysis and found that there were no details included in the paper. The Methods section just ended with the following sentences:

Pre-post changes in self-reports and peer nominations were analyzed using multilevel modeling to account for students’ nesting within classrooms. No baseline condition differences were found on any outcome variables. Further details about method and results are available from the first author.

Based on reviewing the actual paper, I am quite surprised that PLOS One accepted it for publication. There are minimal data presented in the paper, no actual baseline scores regarding peer acceptance or happiness, incomplete methods and the rather grand title of “Kindness Counts: Prompting Prosocial Behavior in Preadolescents Boosts Peer Acceptance and Well-Being” considering the marginally significant data. One is left with many unanswered questions:

1) What if kids had not been asked to perform additional “acts of kindness” or additional visits to “pleasant places” and had instead merely logged these positive activities that they usually performed as part of their routine? This would have been a very important control group.

2) Why did the authors only show brief summaries of the analyses and omit to show all of the actual affect, happiness, satisfaction and peer acceptance data?

3) Did the kids in both groups also become more accepting of their peers?

It is quite remarkable that going to places one likes, such as a shopping mall is just as effective pro-social behavior (performing “acts of kindness”) in terms of improving happiness and well-being. The visits to pleasant places also helped gain peer acceptance, just not quite as much as performing acts of kindness. However, the somewhat selfish sounding headline “Hanging out at the mall makes kids happier and a bit more popular” is not as attractive as the warm and fuzzy headline “Random acts of kindness can make kids more popular“. This may be the reason why the “prosocial” or “kindness” aspect of this study was emphasized so strongly by the news media.

In summary, the limited data in this published paper suggests that children who are asked to intentionally hang out at places they like and keep track of these for four weeks seem to become happier, similar to kids who make an effort to perform additional acts of kindness. Both groups of children gain acceptance by their peers, but the children who perform acts of kindness fare slightly better. There are no clear descriptions of the statistical methods, no actual scores for the two groups (only the changes in scores are shown) and important control groups (such as children who keep track of their positive activities, without increasing them) are missing. Therefore, definitive conclusions cannot be drawn from these limited data. Unfortunately, none of the above-mentioned news reports highlighted the weaknesses, and instead jumped on the bandwagon of interpreting this study as scientific evidence for the importance of kindness. Some of the titles of the news reports even made references to bullying, even though bullying was not at all assessed in the study.

This does not mean that we should discourage our children from being kind. On the contrary, there are many moral reasons to encourage our children to be kind, and there is no need for a scientific justification for kindness. However, if one does invoke science as a reason for kindness, it should be based on scientifically rigorous and comprehensive data.