While conducting the meta-analysis, which included 62 years of collected data, Gershoff looked for associations between parental use of corporal punishment and 11 child behaviors and experiences, including several in childhood (immediate compliance, moral internalization, quality of relationship with parent, and physical abuse from that parent), three in both childhood and adulthood (mental health, aggression, and criminal or antisocial behavior) and one in adulthood alone (abuse of own children or spouse).
Gershoff found "strong associations" between corporal punishment and all eleven child behaviors and experiences. Ten of the associations were negative such as with increased child aggression and antisocial behavior. The single desirable association was between corporal punishment and increased immediate compliance on the part of the child.
The two largest effect sizes (strongest associations) were immediate compliance by the child and physical abuse of the child by the parent. Gershoff believes that these two strongest associations model the complexity of the debate around corporal punishment.
"That these two disparate constructs should show the strongest links to corporal punishment underlines the controversy over this practice. There is general consensus that corporal punishment is effective in getting children to comply immediately while at the same time there is caution from child abuse researchers that corporal punishment by its nature can escalate into physical maltreatment," Gershoff writes.
But, Gershoff also cautions that her findings do not imply that all children who experience corporal punishment turn out to be aggressive or delinquent. A variety of situational factors, such as the parent/child relationship, can moderate the effects of corporal punishment. Furthermore, studying the true effects of corporal punishment requires drawing a boundary line between punishment and abuse. This is a difficult thing to do, especially when relying on parents' self-reports of their discipline tactics and interpretations of normative punishment.