Large, peer-reviewed studies repeatedly show that the more children are hit, the more likely they are to hit others, including peers and siblings. As adults, they are more likely to hit their spouses. The more parents spank children for antisocial behavior, the more the antisocial behavior increases. All of the peer reviewed studies being published continue to confirm these findings.
A major study at Tulane University, published in Pediatrics (http://pediatrics.aappublications.org/content/early/2010/04/12/peds.2009-2678.abstract) controlled for other factors that have been found to contribute to aggressiveness in children, including the mother's depression, alcohol and drug use, spousal abuse and even whether the mother considered abortion while pregnant with the child. Spanking remained a strong predictor of violent behavior in the child. As five-year-olds, the children who had been spanked were more likely than the non-spanked to be defiant, demand immediate satisfaction of their wants and needs, become frustrated easily, have temper tantrums and lash out physically against other people or animals.
Quite simply, spanking produces WORSE behavior, not better behavior. It also begets more violence, because hitting children teaches them that it is acceptable to hit others who are smaller