When it comes to rearing children, no debate is more contentious — or longer running — than the dispute over spanking.
The question of whether a swat on the behind is an acceptable method of discipline has bedeviled parents, divided pediatricians (who were split close to 50-50 in one survey) and spawned impassioned anti-spanking and pro-spanking camps.
PHOTO: Peter DaSilva for The New York Times
Dr. Diana Baumrind found little evidence against mild spankings.
At one end of the spectrum are opponents like Dr. Murray Straus of the University of New Hampshire, who blames spanking for ills including depression, juvenile delinquency, spousal abuse and lowered mental ability. At the other are tough-love advocates like Dr. James Dobson, a conservative Christian psychologist, who advises that "the spanking should be of sufficient magnitude to cause the child to cry genuinely."
The warring sides have argued their cases on Web sites, in scientific journals and in the courts, where anti-spankers have fought to have the practice legally banned and pro- spankers have fought for laws protecting parents who spank from abuse charges.
But a talk given yesterday at the annual meeting of the American Psychological Association in San Francisco is likely to amplify the uproar by several decibels. In it, Dr. Diana Baumrind of the University of California, asserted that social scientists had overstepped the evidence in claiming that spanking caused lasting harm to the child.
"The scientific case against the use of normative physical punishment is a leaky dike, not a solid edifice," Dr. Baumrind said.
Dr. Baumrind, a psychologist known for her classic studies of authoritative, authoritarian and permissive styles of child-rearing, said she did not advocate spanking. But she argued that an occasional swat, when delivered in the context of good child-rearing, had not been shown to do any harm.
The studies cited by opponents of corporal punishment, Dr. Baumrind contended, often do not adequately distinguish the effects of spanking, as practiced by nonabusive parents, from the impact of severe physical punishment and abuse. Nor do they consider other factors that might account for problems later in life, like whether parents are rejecting or whether defiant or aggressive children might be more likely to be spanked in the first place.
Dr. Baumrind described findings from her own research, an analysis of data from a long-term study of more than 100 families, indicating that mild to moderate spanking had no detrimental effects when such confounding influences were separated out. When the parents who delivered severe punishment — for example, frequently spanking with a paddle or striking a child in the face — were removed from the analysis, Dr. Baumrind and her colleague, Dr. Elizabeth Owens, found that few harmful effects linked with spanking were left. And the few that remained could be explained by other aspects of the parent-child relationship.
"When parents are loving and firm and communicate well with the child," Dr. Baumrind said, "the children are exceptionally competent and well adjusted, whether or not their parents spanked them as preschoolers."
The study drew upon data from the Family Socialization and Developmental Competence Project, which followed families in the Berkeley, Calif., area over 12 years, from the time their children were preschoolers until they were adolescents.
Dr. Baumrind argued that, without compelling evidence that spanking is harmful, parents should be free to rear their children in accordance with their own values and traditions.
Dr. Straus, who attended Dr. Baumrind's talk, praised her study.
"It may be the best single study available," he said, in terms of methodology. But the findings did not change his view that spanking is harmful.
"There is not absolutely conclusive evidence but there is very strong evidence, and there's strong evidence that other methods work just as well," said Dr. Straus, a co- author of "Beating the Devil Out of Them: Corporal Punishment by American Families and Its Effects on Children."
Dr. George Holden, a professor of psychology at the University of Texas, agreed that many spanking studies were flawed. But Dr. Holden said enough studies had found harmful outcomes to suggest that spanking was "a damaging practice in certain cases under certain situations."
For his part, Dr. Straus said that, as in many scientific debates, each side tended to marshal the evidence that supported its view.
In fact, two scholarly reviews, one by a researcher who does not oppose spanking and one by a researcher who does, came to very different conclusions.
Dr. Robert Larzelere of the University of Nebraska Medical Center reviewed 38 studies and found that in children under 7, nonabusive spanking produced no harmful effects and reduced misbehavior when used as a backup for milder discipline techniques like reasoning or timeouts.
In other studies, however, children older than 6 did show detrimental effects when spanking was used too often, for example, three or more times a week.
The review was published last year in the Clinical Child and Family Psychology Review.
Dr. Larzelere said that he advocated "conditional, nonabusive" spanking, which he defined as "two open- handed swats, not out of control due to anger" as a backup for children between the ages of 2 and 6.
In contrast, Dr. Elizabeth Gershoff, an associate research scientist at Columbia University's National Center for Children in Poverty, conducted an analysis of 88 studies. Dr. Gershoff concluded that corporal punishment was associated with 10 negative effects, like increased aggression and a higher risk of being physically abused, and one positive outcome: immediate compliance. The review will appear in the journal Psychological Bulletin next year.
"I think that parents would be best off trying to avoid using corporal punishment, because it appears that there is a risk for certain negative long-term consequences," Dr. Gershoff said.
Her view coincides with guidelines issued in 1998 by the American Academy of Pediatrics, which recommend that "parents be encouraged and assisted in developing methods other than spanking in response to undesired behavior."
A majority of American adults still endorse spanking as a disciplinary tool, though that number has dropped over the last three decades. And a 1999 study found that 94 percent of 3- and 4-year-olds in the United States had been spanked at least once by a parent in the last year.
In deciding how to discipline their children, many parents say they rely on their pediatricians' advice, the model provided by their own parents, their religious beliefs or their own experience of what works.
Lisa Many, for example, a legal assistant in Chapel Hill, N.C., said that she had spanked her children a few times in frustration but that she did not believe in the practice or think it was effective.
"I've probably spanked my son maybe three or five times, and my daughter maybe three or five times," Ms. Many, 37, said. "All it does is gets them angry. I mean it gets their attention, but in the long run, I don't know."
And Ms. Many said spanking left her with "a terrible feeling."
On the other hand, Michael Shannon, 47, of Clemmons, N.C., said he and his wife decided years ago to spank their three children, now 15, 20 and 22, because they found that timeouts did not always work when the children were small.
"It seemed to get our child's attention a lot quicker," Mr. Shannon said.
He said he had been spanked with a paddle by his own father and did not believe it had negative effects.
"My parents weren't strict," Mr. Shannon said, "But I knew where the line was right away."
Dr. Holden said one problem in understanding spanking's effects was that researchers were only beginning to study the practice in any depth.
Some parents spank emotionally. Others spank with the firm belief that it is necessary to socialize their children. And children react differently to being spanked.
"Like all social behaviors, spanking is pretty complex if you dig into it," Dr. Holden said, "and a lot of that complexity has been completely ignored by previous researchers."