A new report from the American Academy of Pediatrics highlights the serious, lasting effects that psychological abuse can have on children.

Since there is no universal definition of psychological abuse, the authors break down various offenses into categories, including "spurning" (which can mean belittling children or making fun of them for showing normal emotions), "terrorizing" (placing kids in unpredictable circumstances, for example) or "isolating" (confining them in a space or restricting their social interactions).

And while many of those behaviors may seem obviously hurtful, not all forms of psychological abuse are. The report, published in the journal Pediatrics on Monday, points out that much of what hurts children goes beyond clear-cut forms of emotional or mental maltreatment.

"Many are things that parents may, very appropriately, do in isolated circumstances," said Roberta Hibbard, director of Child Protection Programs at Indiana University's School of Medicine and one of the report's authors.

"For example, it's often appropriate to send children to their room and put them in time-out," she said. "But at what point does three minutes become five minutes, and five minutes becomes 10 hours?"

Parents, Hibbard said, sometimes have a difficult time knowing where that limit is.

"It's hard to distinguish what is a single incident of poor parenting or one indiscretion where you say something critical, versus something that would qualify as abuse," said Alec Miller, chief of child and adolescent psychology at the Montefiore Medical Center in New York, who was not involved with the new report.

"As a parent myself, I'm fallible. I make mistakes," he said. "And yet I try not to repeat my mistakes."

The report stresses that repetition usually signals that a behavior has gone from being an error or lapse and has become abuse. Repeatedly making children feel unloved or unwanted, or even certain non-actions, qualify. The latter can include denying a child emotional responsiveness, or being detached and uninvolved.

Given how many actions and behaviors can fit under the broad umbrella of "psychological abuse," its burden has been difficult to track.

Between 8 and 9 percent of women and 4 percent of men say they were exposed to severe psychological abuse as children, according to both U.K. and U.S. studies cited in the new report, which updates a 2000 report also issued by the American Academy of Pediatrics.

What is essential, the authors write, is to make sure pediatricians know how to look out for psychological abuse, just as they would physical or sexual maltreatment.

Experts must also help come up with effective treatment and prevention programs, and spread awareness among anyone who takes care of children that psychological abuse can cause major, long-term problems.

"A lot of attention is paid to sexual and physical abuse," Miller said. "This is another form of child maltreatment that is more insidious, in some instances, and it doesn't get the treatment attention that is due."