Research: Spanked children have lower IQs

Those against corporal punishment may have found support in research presented last fall that suggests kids who are spanked have lower IQs than kids who are not.

Murray Straus, Ph.D., a sociology professor and co-director of the Family Research Laboratory at the University of New Hampshire and Mallie Paschall, Ph.D., senior research scientist at the Pacific Institute for Research and Evaluation, studied nationally representative samples of 806 children ages 2 to 4 and 704 children ages 5 to 9. They looked at the children’s IQ scores and how often the kids were subjected to corporal punishment, as reported by their mothers. When the researchers retested the children’s IQ four years later, they found the younger children who had been spared the rod had gained five IQ points compared to kids who had been spanked, while older children who hadn’t been spanked gained 2.8 points.

How often children were spanked seemed to make a difference, though even infrequent spanking appeared to have an effect, Straus says. The findings were announced at the 14th International Conference on Violence, Abuse and Trauma in San Diego, Calif.

The relationship between spanking and IQ is complex and is likely bidirectional, Straus acknowledges. Parents may hit because their child isn’t doing something right – which may have to do with cognitive ability – without realizing their actions might be harmful in the long run.

“Corporal punishment is very stressful for kids and affects the brain very deeply,” he says. Comparing brain scans of children who have endured a lot of corporal punishment with those of children who haven’t suggests that corporal punishment permanently affects brain structure, he adds.

The stress involved in physical punishment might hinder concentration; it also may short-circuit language development and emotional expression. Research shows the more parents talk to children, the larger their vocabulary and the higher their IQ. Spanking, on the other hand, may seem a quick fix.

“Parents might think ‘I don’t have time to explain to a child, I know something that works,'” Straus says. Hitting also weakens the bond between parent and child, he adds, so that down the road, if a parent is trying to get a child to study, the message might not be taken as seriously. In an earlier paper, Straus and Paschall cited research that’s found that even after taking parental education and occupation into account, children who have experienced corporal punishment are less likely than other kids to graduate from college.

Working with colleagues in 32 countries, Straus also found that nations in which spanking was more prevalent had a lower average IQ. The relationship between corporal punishment and IQ was strongest for people who continued to be hit as teenagers. Straus acknowledged that a higher level of economic development might underlie both fewer parents using corporal punishment and a higher national IQ.

Today, corporal punishment appears to be declining worldwide. It is banned in 29 countries, including three that have outlawed it this year.