If certain omitted variables are correlated with both, we may confound the two effects, that is, inappropriately attribute an effect to spanking.For example, parents who spank their children may be weaker parents overall, and spanking is simply one way in which this difference in parenting quality manifests itself.A 2009 study examined two cohorts of children within the National Longitudinal Study of Youth (NLSY) and found that, even controlling for other parenting behaviors and demographics, children of mothers who used little or no corporal punishment “gained cognitive ability faster than children who were spanked.” Mac Kenzie et al.(2013) show that father’s high-frequency spanking at age five was associated with lower child vocabulary scores at age nine.Emerging evidence suggests that non-cognitive skills may also be affected.In an experimental study, Talwar, Carlson, and Lee (2011) tested whether attendance in a punitive versus non-punitive school environment had any effect on West African children’s executive functioning (EF) skills.[iii] They measured children’s abilities using three EF tasks: delay of gratification; gift delay; and dimensional change card sort.
Figure 2 shows the distribution of responses, where refers to a mother who did not hit her child in the previous week or during the observation.
As expected, the gaps between mothers who hit and do not hit decrease by about one for both items.[iv] But the resulting gaps are miniscule—just over one-half of a point—and fall well within one standard deviation of the HOME score distribution.
Most studies suggest, however, that spanking becomes problematic with increased frequency and/or intensity.
There is also robust evidence of an increased incidence of aggression among children who are regularly spanked.
A 2002 meta-analysis of 27 studies across time periods, countries, and ages found a persistent association: children who are spanked regularly are more likely to be aggressive, both as a child and as an adult.