(DALLAS) -- Researcher George Holden set off to study how often parents yelled at their children, but after listening to 36 hours of real-time audiotapes he heard something else -- the cracks of spanking and the screams that followed.
Most of the behavioral incidents were "petty" in nature, according Holden, a professor of psychology at Southern Methodist University in Texas, but the punishment was "virtually all highly inappropriate."
In one incident recorded on tape, a mother spanked her 3-year-old 11 times for fighting with his sister and is reduced to tears and coughing. One child was punished for not cleaning his room. Another was slapped for being overzealous during a bedtime story by pointing and turning the page.
"They were pretty shocking," said Holden, who has written five books on child development.
"They highlight that so much of corporal punishment are misguided notions of parenting that are bad for the child," he said. "It's sad that a parent inadvertently ruins the quality of their relationship by jumping on the child for being a normal kid."
The study, Real Life Mother-Child Interaction in the Home, was conducted over six nights, when parents and children were most tired. Holden found 36 mothers and one father at Dallas day care centers who agreed to leave a tape running between the time they got home and put the kids to bed.
The parents were evenly divided from all economic backgrounds. Most were white and a third were African Americans.
So as not to skew the study, they were told that it was about parents' interaction with their children.
"The vast majority -- 90 percent of parents -- admit yelling at their kids, but we didn't have a good data what is it like," Holden told ABC News.
But the tapes showed more than yelling.
"We have not totally coded all the tapes yet, so we actually expect to find a lot more examples of this inadvertent window into parents' use of corporal punishment," said Holden. "It presents a unique view that no one ever had before about what goes on in these families."
Holden presented his study this month in Dallas at the Global Summit on Ending Corporal Punishment and Promoting Positive Discipline and it was reported in Time magazine.
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