The latest study by a veteran analyst of the ill-effects of corporal punishment has uncovered evidence that spanking can damage young children’s developing intelligence. 

The research team led by Murray Straus at the University of New Hampshire investigated the impact of spanking on a representative sample of over 1,500 US children, drawn from the National Longitudinal Survey of Youth.

Reported in the Journal of Aggression, Maltreatment & Trauma the study analyzed data on over 800 children between the ages of two and four, and another 700 between the ages of five and nine, all of whom who grew up during the 1980s. 

At the outset, the National Longitudinal Survey collected information about the cognitive ability of the children and how often they were hit. Cognitive ability was tested again four years later.

Children in the younger age group who experienced corporal punishment scored an average of five points lower on an IQ test than their contemporaries. The same pattern was seen among the older age group, although it was less pronounced, with a 2.8 point gap. The distinction held true after taking into account parental education, income and other environmental variables. 

Spanking younger children is often thought of as more acceptable, Straus suggests. “There is a cruel irony to this, because it is precisely at early stages of development that avoiding spanking and using cognitive modes of correction may be the most beneficial.” The neural connections of younger children are at a more critical stage of development. 

Talking and reasoning with children energizes brain development; hitting children is associated with fright or stress, says Straus. Children experiencing corporal punishment may find it harder to focus and learn.

Defenders of corporal punishment also argue that spanking children occasionally will do them no harm. However, there are suggestions in the New Hampshire findings that the frequency with which kids were punished in this way made a difference. The more often children were spanked, the slower their cognitive development. Even small amounts of spanking made a difference.  

What is not clear is whether spanking inhibits cognitive development or lower cognitive ability induces more spanking. It is possible, Straus concedes, that children whose reasoning skills are relatively poor or who misbehave more often are likely to suffer harsher punishment. The relationship probably works in both directions, he adds.

But, cause or consequence, a violent response is always counter-productive. 

Presenting his findings at the International Conference on Violence, Abuse and Trauma in San Diego, Straus urged psychologists to help parents desist from corporal punishment and to incorporate this objective into their clinical practice. 

See: Straus M A and Paschall M J (2009) “Corporal Punishment by Mothers and Development of Children’s Cognitive Ability: A longitudinal study of two nationally representative age cohorts,” 18, 5, pp 459-483.