Corporal punishment as a means to deter certain bad behavior remains one of the more controversial parenting techniques. While some parents favor a simple timeout or a face-to-face conversation, others choose to curb bad behavior physically and immediately. While lay opinions remain divided, a new study adds to the evidence that spanking provides no advantages to a children’s development, and could actually make them more aggressive later in life.

Children who get spanked as early as age 5 have demonstrably more aggressive tendencies by the time they reach 9 years old, according to researchers at Columbia University. Using the Fragile Families and Child Well-Being Study, a longitudinal study of kids who live in single-parent or impoverished households across 20 U.S. cities, the team found spanking had significant negative effects in terms of physical behavior. Moreover, it caused slight declines in cognitive development as well.

The present study echoes past research, some of which even goes as far to implicate spanking as a precursor to anxiety disorders and alcohol abuse. Other studies found less of an association, though while they profess there to be no disadvantages, they concede the advantages are slim to none, too.

"There's just no evidence that spanking is good for kids,” Professor Elizabeth Gershoff, of the University of Texas at Austin, and who was not involved in the study, told Reuters Health. "Spanking models aggression as a way of solving problems, that you can hit people and get what you want.”

The problem, as Gershoff sees it, is that parents who spank their kids are implicitly telling them that physical force should be the default way to resolve conflict. "When (children) want another kid's toy, the parents haven't taught them how to use their words or how to negotiate,” she said.

Despite over a decade of research into its harmful effects, the practice is still widely used in the United States. One 2000 survey found 61 percent of parents believed spanking was an acceptable form of punishment. And it’s even more prevalent in Eastern parts of the world, but history seems to suggest legislation may have a hand in slowing its acceptance. Before a 1979 ban on corporal punishment, Sweden saw more than half its population spanking their kids. By 1996, the rate had fallen to 11 percent.

"Most kids experience spanking at least some point in time," Dr. Michael MacKenzie, lead author of the present study, told Reuters Health. "So there's this disconnect."

Parents involved with the study, overseeing roughly 1,900 children, answered questions about their spanking habits and how their children behaved later in life. The team surveyed parents when their kids were 3 and 5 years old, and also administered a vocabulary test at age nine.

Fifty-seven percent of mothers and 40 percent of fathers reported spanking their kids when they were 3 years old. At age 5, that rate fell to 52 percent of mothers and 33 percent of fathers. On the team’s 70-point scale of aggression, children who were spanked twice a week at age 5 scored, on average, two points higher. The team found no link between spanking at age 3 and negative behavior later in life.

The average vocabulary score for all 9-year-olds in the study was a 93, with the test average calibrated to 100. And while the researchers couldn’t be sure the difference was due to chance, a four-point difference was also observed among children whose fathers regularly spanked them.

The data is admittedly foggy, but it’s clear enough to MacKenzie and his colleagues that spanking doesn’t confer any benefits on a child’s upbringing.

"We know that spanking doesn't work, we know that yelling doesn't work," Gershoff added. "Timeout is kind of a mixed bag. We know that reasoning does work."

Given the population breakdown of the study — namely, “fragile families” — the findings have more explaining to do when it comes to more stable homes. As the team acknowledges, families that live in strained circumstances often direct their stress and frustration toward their children.

The goal, many experts argue, is to work with doctors in establishing healthy ways to relieve that stress, and discipline children more safely. Unfortunately, for a family with limited resources, patience isn’t always an option.

"The techniques that are designed to promote positive behaviors,” MacKenzie said, “oftentimes take more effort and time to put into place.”

Source: MacKenzie M, Nicklas E, Waldfogel J, Brooks-Gunn J. Spanking and Child Development Across the First Decade of Life. Pediatrics. 2013.