Smacking Hits Kids' IQ

Sept. 27, 2009— -- A good spanking may leave a mark on a child that's worse than the red handprint. Spanking and other corporal punishments stunt children's intelligence, new research shows.

The IQs of 2- to 4-year-olds who received regular spankings from their parents dropped by more than 5 points over four years, compared with kids who were not spanked.

"The practical side of this is that paediatricians and child psychologists need to start doing what none of them do now, and say, 'Never spank under any circumstances,'" says Murray Straus, a sociologist at the University of New Hampshire in Durham, who led the new study along with Mallie Paschall at the Prevention Research Center in Berkeley, California.

Theirs isn't the first evidence that spanking children comes with a cost: several previous studies have hinted at the association, and a recent brain-imaging study found that children who underwent severe corporal punishment had less brain grey matter – which includes neurons – compared with other children. Stress, anxiety and fear might explain why spanking slows cognitive development.

However, the new research makes a stronger case for a cause-effect relationship between spanking and intelligence than other studies, says Elizabeth Gershoff, a child development researcher at the University of Texas, Austin, who was not involved in the new study. This is because it examined children over the course of four years and accounted for many confounding variables, such as a parent's ethnicity, education and whether they read to their children or not.

Straus and Paschall analysed data collected in the 1980s as part of a nationwide survey of children's health. In 1986 a previous study measured the IQ of 1510 2- to 9-year olds and also noted how often their mothers meted out corporal punishment. The researchers repeated the IQ tests four years later.

Straus and Paschall split the kids into two age groups – 2 to 4 years and 5 to 9 – because some child psychologists contend that occasional spanking is acceptable in toddlers, but not older children.