Bluntness, for example, is a virtue. Saying to a child, “Would you put your toys back in the box, please?” turns a command into a question. Saying, “Let’s put your toys back in the box,” implies collaboration. An unadorned “Put your toys back in the box” is clearer for everyone, psychologists say, especially so for a child who is highly distractible.

However it is dressed up, family therapy like this teaches parents to provide what many critics say children these days are missing — discipline. But therapists make a careful distinction between corrective action and cruelty, between firmness and frostiness. Overly punitive parents increase the likelihood that a child will develop mood problems, some studies suggest. So parents learn not to become scolds, but to bring their children into line without demeaning them.

In some programs, parents play-act situations in front of their peers, who critique the performance for emotional tone and the clarity of parents’ statements. As a result, the parents say, they become immediately more deliberate at home. “You end up constantly saying things like, ‘That’s not an appropriate behavior,’ using this unnatural language,” said Ms. Popczynski. “But the point is you don’t get into it with them. The first thing I noticed was that I wasn’t yelling all the time. The house got a lot quieter right away.”

Their instructions to Peter and Scott became more precise, as well. Saying “Clean your room” is too vague and covers a half-dozen tasks, Roman Popczynski, the boys’ father, said. Peter might wonder where to start, or just decide it was too much to worry about, and give up, his father said. “Put your laundry in the hamper” is much more likely to get results, he said, and lead to the next clear step, like “Put your toys where they belong.”

Multiple commands are also confounding: “Put away your crayons, clear away the table, and organize your homework, please” leaves a child wondering which to do first, and whether it is too much work to finish. “It overloads a kid, and then he feels like he’s failing, which only makes it worse,” said Mr. Popczynski, who is a UPS driver.

Starting Slowly

Like most who try to use behavior modification techniques, the Popczynskis relied on a daily report card to keep a running tally of Peter’s specific problem behaviors, like wandering attention, ignoring commands or defiance, and his efforts to correct them.

For instance, at the beginning, Peter, then 7, would get a check mark every time he ignored more than two commands to do his homework, put away his toys or brush his teeth, but he would earn immediate praise if he got started. He received check marks when he slid off his chair at dinner, and earned approval if he stayed seated.