The majority of U.S. children have been spanked at some time in their life, despite a robust body of evidence suggesting that spanking a child leads to problems.
The latest evidence of the negative effects of spanking comes from researchers at Columbia University. After analyzing data from more than 1,500 families, they found that children who are spanked in early childhood are not only more likely to be aggressive as older children, they are also more likely to do worse on vocabulary tests than their non-spanked peers.
The study was published this week in the journal Pediatrics.
While several studies have found a connection between spanking and aggressive behavior, the finding that spanking could be linked to cognitive ability is somewhat new.
"Only a few studies have looked at the cognitive effects of spanking," said Michael MacKenzie, an associate professor at Columbia University and lead author of the study. "We are still trying to learn if spanking has a direct effect on early brain development, or if families that spank more are less likely to read to their kids and use more complex language."
MacKenzie analyzed data collected from more than 1,500 families as part of the Fragile Families and Child Well-Being Study. The study followed children from 20 U.S. cities from birth to age 10. Most of the children were born from 1998 to 2000.
The study collected other data that might influence a 9-year old's behavior and performance on the vocabulary test, including the age of the mother when the child was born, the mother's self-reported stress levels, her intelligence scores, and her own impulsivity. The researchers also had indicators of low birth weight and temperament during the first year of life.
But even when the researchers controlled for these differences, "we still saw that spanking is an influencing factor in future behaviors."
"Spanking is still the typical experience for most kids," he said. "We have to start being more thoughtful about how we present this information for parents in a way that they can receive it."