Recent research suggests that there is no experimental evidence to prove that corporal punishment is an effective method of disciplining children. The results of this study show that alternative, non-physical strategies can be just as effective at encouraging children’s cooperation, without the potential risks associated with spanking. The study was published in the journal Child Abuse and Neglect.
Spanking remains a widespread form of discipline and is considered normative and socially acceptable in many cultures. Despite disapproval from some health organizations, it is estimated that two out of three children between the ages of two and four are spanked worldwide.
Scientists conducted this new study in response to the continuing debate about the benefits of corporal punishment. Recently, some scholars have published commentaries claiming that rigorous experimental testing has provided evidence that spanking is an effective method of coercing child obedience. These advocates argued that laws prohibiting physical discipline are wrong and that spanking should remain an option available to parents.
“We considered this topic because a recent invited commentary in a psychiatry journal recommended the use of spanking as a means to enforce compliance in children. The authors claimed that the effectiveness of spanking has been tested in the ‘most rigorous’ clinical trials, specifically (randomized controlled trials),” said Leslie Atkinson of Toronto Metropolitan University, corresponding author of the new study.
“They further argued that studies showing a positive association between spanking and developmental difficulties (e.g., behavioral or emotional problems in children) were not designed to assess causality (e.g., a child’s behavioral difficulties may lead to further spanking, rather than vice versa). They concluded that spanking is an effective disciplinary strategy.”
“We were surprised by this perspective because the United Nations Convention on the Rights of the Child requires children to be protected from corporal punishment. Currently, only 70 countries have signed this convention.”
This discussion is highly relevant to current legal battles in North America. The United States is not a signatory to this convention and does not legally prohibit corporal punishment at the state or national level. In Canada, the Supreme Court previously upheld the use of reasonable physical force for correction, but this decision is currently being challenged in Parliament.
Scientists wanted to evaluate the scientific basis of the claims supporting these laws. They looked at four specific clinical trials published between 1981 and 1990. Proponents of physical discipline often cite these four studies as evidence that spanking works.
Researchers sought to determine whether these old studies actually met modern scientific standards. They also wanted to evaluate a combined analysis of some of these studies, known as a meta-analysis. Meta-analysis is a statistical method that combines the results of multiple independent studies to find overall trends.
Past meta-analyses have historically influenced court decisions and professional pediatric guidelines. However, scientists have identified statistical problems in favor of spanking in several past meta-analyses. Many of these previous reviews examined only one or two narrow measures of children’s compliance, ignoring the variety of other behavioral outcomes recorded in the original trials.
Some previous reviews also used mathematical methods that tended to artificially exaggerate the apparent success of interventions. For example, rather than directly comparing the final behavior of the spanked group to the non-spanked group, we measured the change in behavior from before to after the discipline. This statistical choice breaks the rules of randomized experiments and exaggerates the reported benefits.
Their goal was to objectively assess whether these four old tests really support the claim that spanking is superior to non-physical discipline. To assess the evidence, researchers first conducted a detailed review of four historical trials. These trials originally tested spanking as a back-up method for forcing time-outs in dissident children ages 2 to 6.
In these old experiments, the mother would have the child sit in a chair for a time-out. If the child tries to leave the chair, the mother uses another assigned strategy. These strategies included spanking the child, holding the child back in the chair, or placing the child in a room blocked off by a plywood barrier.
In other conditions, the child was allowed to leave the chair without penalty or without any consequences. The sample size for these first experiments was very small. Only four, eight, or nine mother-infant pairs were included for each experimental condition.
Researchers evaluated the designs of these trials using standardized tools designed to detect bias in scientific research. They found that three of the four trials were at high risk of bias due to flawed procedures by modern standards. For example, the way children were assigned to different disciplinary groups was not strictly randomized.
When looking at the oldest trial, conducted in 1981, researchers noticed a major design flaw that had been overlooked in previous reviews. Children in the spanking group spent significantly more time in the time-out chair than children in the non-physical group. This means that the child’s increased cooperation may be due to the longer time-out period, rather than the spanking itself.
The researchers also determined that the original study lacked external validity. External validity refers to the extent to which research results apply to real-world situations and diverse populations outside of laboratory settings. The original trial only included mothers who were in highly controlled clinical settings more than 30 years ago, so the results do not easily translate to modern families.
In addition to outdated clinical settings, original experiments tested children only on certain types of instructions, such as telling a child to pick up a toy. They never tested instructions that would get children to stop bad behavior. Research provides evidence that a child’s willingness to comply with direct commands does not necessarily predict whether he or she will refrain from prohibited behavior.
Attitudes toward child rearing have also changed significantly since the 1980s. New research suggests that the psychological impact of physical discipline is greatly influenced by how common and accepted the practice is within a particular community. Because the original trial took place decades ago in a single, narrow context, it cannot account for these broader cultural changes.
After reviewing individual trials, scientists conducted their own updated meta-analysis. This new analysis combines data from four trials involving a total of 68 mother-infant pairs.
Scientists compared the effectiveness of spanking to all other non-physical strategies combined. They calculated the effect size, which is a number that represents the strength of the relationship between two variables. To account for the very small sample sizes in older studies, the scientists used a special statistical metric called Hedges’ g that was designed to avoid exaggerating results.
They also calculated confidence intervals to estimate the range of spanking’s true effects. The resulting range is very wide, which indicates a very high level of uncertainty about the actual effectiveness of physical training. Ultimately, the researchers found no significant difference in effectiveness between spanking and alternative strategies combined.
Specifically, when we compared spanking with a strategy that allowed the child to end the time-out early, the difference in compliance was not statistically significant. The findings were based on data from two trials involving 34 mother-infant pairs. Similarly, spanking is not significantly more effective than using a physical barrier to force a timeout.
In fact, the data provided evidence that barrier methods tended to be slightly more effective, although the difference was not significant. This comparison is based on data from three trials involving 34 pairs. The scientists also compared spanking to physically pinning a child to a time-out chair.
Based on data from a single trial of 18 pairs, spanking did not prove to be more effective than holding. Finally, we found that spanking actually causes more destructive behavior during timeouts compared to simply leaving the child in the room. Taken together, these statistics show that spanking does not reliably outweigh non-physical discipline.
“We decided to evaluate the literature underlying claims about the effectiveness of spanking,” Atkinson told SciPost. “The literature consists of four controlled trials published between 1981 and 1990 and a meta-analysis of these trials published in 2024. We reviewed the trials one by one and found that 1) they were poorly designed by current standards and had a high risk of bias, 2) they provided at best vague support for spanking, and 3) We found that such support was relevant in a very limited context; and 4) the results could not be generalized to today’s population.
These new findings differ from some recent publications that recommend limited spanking. For example, a recent review of long-term observational studies suggests that occasional mild spankings have minimal negative behavioral effects. That particular study claimed that for parents of young children, spanking can be an effective back-up tool when gentler responses fail.
Another previous analysis by scientists at Purdue University also suggests that clapping less frequently may reduce defiant behavior. These researchers looked at annual data for children ages 6 to 8 in Tennessee and Indiana. They argued that previous studies have been unable to separate personality differences from the effects of discipline itself and have exaggerated the harm of spanking.
At the same time, this new finding is consistent with extensive global research highlighting the potential risks of physical discipline. For example, a recent large-scale study of children in Bhutan, Cambodia, Ethiopia, and Rwanda found that spanking negatively impacts cognitive and emotional development. The international study showed that children who were spanked performed worse in numeracy, literacy, and emotional regulation.
The debate over the effectiveness of spanking is hampered by very few experimental results. Modern ethical guidelines prevent scientists from conducting new experiments such as hitting children, so it is likely that the available experimental data will always remain scarce. This lack of data undermines the certainty of broad statistical conclusions. Small sample sizes mean that mathematical estimates of effectiveness are relatively unstable.
Still, researchers emphasize that this lack of evidence is precisely the point. People cannot claim that experimental evidence proves the effectiveness of spanking when existing experiments are so limited and flawed.
“Our meta-analysis was based on just four spanking trials available (and likely more to come due to ethical considerations),” Atkinson said. “This deficiency undermines the robustness of our meta-analysis results. However, at this time, there is no experimental evidence supporting the effectiveness of spanking, which contradicts claims to the contrary.”
“Other literature indicates that corporal punishment is associated with negative developmental outcomes, but the causality of these findings is unclear. Taken together, this literature suggests that the most prudent parenting strategies include positive, relational parenting that has been proven to be effective (e.g., positive reinforcement, especially praise, and natural/logical consequences).”
“At this point, it’s safe to say that the use of corporal punishment is a high-risk parenting strategy,” Atkinson concluded.
The study, “Is there any experimental evidence for the effectiveness of punitive spanking? A review and meta-analysis of four controlled trials,” was authored by Leslie Atkinson, Jennifer Cooley, Megan Kenny, and Andrea Gonzalez.
