Knowing When to Say ‘No’ : Child psychology: Parents can break bad habits without squelching creativity, experts say.

This was the young mother’s question for the famous child psychologist: Her baby throws food from the highchair. Should she forbid it?

“I don’t mind cleaning it up,” she said.

Another mother at the talk Dr. Lee Salk recently gave in Waterbury, Conn., wanted to pursue the topic. If you stop the baby from throwing the food, she asked, doesn’t that deprive the child of learning about cause and effect?

What is it that makes parents so unsure that they cannot decide how they feel about their children reflooring the kitchen with mashed potatoes?

“They have trouble knowing what to do, and they’re anxious,” said Salk in a phone interview from New York, where he practices and is a professor of psychology, psychiatry and pediatrics at Cornell University Medical College. “There’s a fear that by letting the baby do too much, they will be ‘spoiling the baby.’ And by setting any limits, you will be constricting them. But you’ve got to do both.”

It would be great if there were a consensus: Allow your baby to do these things; forbid him to do those. But after forbidding any dangerous activity--playing with electrical outlets or the stove--you are back to the tough business of being a parent: making judgment calls. You have to consider what the child is capable of and his or her need to explore.

When a baby plays with an outlet, a parent will say “no,” and the baby gets the idea that the parent disapproves, said Dr. Charles Zeanah, associate professor of psychiatry and human behavior at Brown University in Providence, R.I. “That doesn’t necessarily mean that the children have learned the lesson that they’re not supposed to do that, and it doesn’t necessarily mean that a 1-year-old is defying the parents, thinking, ‘They don’t want me to do this, but I’m going to do it anyway’ if they go back and play with it again.”

Generally, children must be at least 18 months old before they can really understand the rules.

Children need to explore, but “if they don’t know what the limits are, then the child doesn’t really figure things out,” Salk said. “If you let your child pick up a bunch of peas and slam them against the wall, and you smile and think what a great artistic production this is, you’re not preparing this child for the real world.” Provide crayons or paints at other times.

But you can’t expect a 1-year-old to see the house as you do.

“Toddlers in particular are fascinated with making things happen. They develop all sorts of irritating habits like turning light switches on and off--anything they can do that can make something exciting and different happen,” Zeanah says. “When they find something unfamiliar, they practice it over and over again. . . . It’s a good thing for kids to do that. You don’t want to come down too hard. But when you don’t want them to turn the TV on and off, it’s a good idea to have some alternative to offer them. That doesn’t squelch the urge to master things but at the same time achieves your goal of trying to get them away.”