Spanking and Physical Punishment Effects on Children

I had a recent discussion with a friend on the effectiveness and/or trauma caused by physical punishments for misbehaviour for children. The most pointed to paper by articles and AI alike is this 2016 meta-analysis titled Spanking and Child Outcomes: Old Controversies and New Meta-Analyses. It provides the best view on corporal punishment effects and effect sizes while differentiating between spanking/light physical punishments and what would be deemed abusive behavior. The paper reviewed two concerns about the existing research:

1. Spanking Has Been Confounded With Harsher Forms of Physical Punishment

2. Spanking Has Only Been Linked With Negative Child Outcomes in Cross-Sectional or Methodologically Weak Studies

By coding the the types of physical punishments, the meta-analysis removed abusive behavior from the analysis and built bivariate links; relationships between spanking and one single outcome. It compared more spanking, less spanking, and in some studies no spanking. By coding papers based on type like cross sectional vs longitudinal, it evaluated outcomes based on the study type. Its conclusion:

The meta-analyses presented here found no evidence that spanking is associated with improved child behavior and rather found spanking to be associated with increased risk of 13 detrimental outcomes. These analyses did not find any support for the contentions that spanking is only associated with detrimental outcomes when it is combined with abusive methods or that spanking is only associated with such outcomes in methodologically weak studies.

The detrimental outcomes are interesting to examine, a litany of issues with the biggest including being a victim of physical abuse, child mental health problems, and negative parent-child relationships.

Two other studies reinforce this finding. A 2021 review in the Lancet stated:

Our review of prospective longitudinal studies has shown that physical punishment is linked with increases in negative child outcomes. Many of these studies used statistical methods to minimise potential confounding and selection bias. The review has documented compelling evidence that physical punishment is harmful to children’s development and wellbeing and has shown no evidence that it is beneficial for children.

And this 2025 meta-analysis found similar results when examining studies focused on lower and middle income families. This controls for confounding factors like norms or socioeconomic factors.

It is not surprise that the read from AI on the matter is that overwhelming strength of evidence lies against physical punishments, often in line with UN calls to uphold children's human rights against this type of means of compliance.

That being said, I retain some skepticism on the results. As the 2016 meta-analysis pointed out:

parents’ use of spanking is not easily or ethically studied through an experimental design, as children cannot be randomly assigned to parents with varying predispositions to spank, nor can parents typically be randomly assigned to spank or not spank...The circumstances of experimentally manipulated spanking thus are likely to be unusual, leading to concern that experiments with parental spanking may suffer from a lack of external validity.

The study says their results show little reduction in negative outcomes when comparing weaker cross sectional studies against more powerfully designed prospective longitudinal studies but I find this reasoning limited because prospective longitudinal studies still lack the ability to control for some confounding factors like a child's baseline behavior. The directionality of outcomes and spanking is in my view still a question and not well controlled.

Coding of physical punishment was also largely self reported. I question the strength of this coding as the ambiguity between abuse and controlled punishment is not verified nor blinded.

Finally, a 2005 study controlled for cultural norms. In countries where physical punishment is more common, it found the negative outcomes dampened but still persistent. With examples like Singapore that still incorporate caning as a punishment means for extreme cases, I think the literature has gaps on how well managed punishment systems effect outcomes.

TLDR; My read

The evidence is clear that the higher end of physical punishment in terms of harshness and volume is strongly associated with negative outcomes for the child. And these observations persist across cultures and socioeconomics. The line between physical punishment and abuse is thin and I believe easily crossed. This is a two way bridge for the evidence, as I think that makes controlling for limited and well defined proportional physical punishment difficult to design and assess.

The 2016 meta-analysis was clear in its conclusion, but the majority of the evidence it examined was showing impacts of more spanking vs less spanking and wasn't designed to analyze spanking vs non-spanking. I think it is clear that at best physical punishments should be used as sparingly as possible if at all. However, I don't think its fair to say the evidence discounts any physical punishment as the ability to create experiments is infeasible. I'd also contend that that conclusion of no physical punishments is culturally loaded and invites societal bias and judgement. As a rule parents should exhaust other means of punishment first.