Question: My 4 1/2 -year-old daughter is a monster from hell when she watches more than an hour of television a day. When she doesn’t get television, she acts like she’s withdrawing from heroin — regresses to baby state, screams, acts out, constant tantrums. Is this normal? We have had periodic blackouts, which are miserable. Is it time to just cut the cord entirely and live with it? Or try a moderate diet? Neither is going to be a happy state for our family.

Answer: These are some great and vexing questions for you and much of society today.

When your daughter (let’s call her Jenny) watches TV for more than an hour, she doesn’t listen, becomes obstinate, hard to direct and ends up screaming like a banshee. (You don’t say that’s exactly how she acts, but trust me, I know.)

Periodic blackouts don’t seem to work, so trust your instinct when you talk about “cutting the cord entirely.”

Which leads me to this: boundaries. The definition of a boundary is “a line that marks the limits of an area; a dividing line.” I like this definition because we can see more clearly what we are trying to do as parents.

Boundary setting can be clear and easy or confusing and tough. For instance, when it is time to place a child into a car seat, this is a clear and easy boundary. “In order to be in the car, you must be secured.” No debate. Does this mean the child enjoys it? No. But no amount of screaming will undo this boundary. Ever.

The boundaries around technology get a little fuzzier, don’t they?

Jenny is not in mortal danger when she watches TV. And yet, you must create a boundary because this situation is not working.

Jenny is having trouble. Her young brain loves the whirling lights and action so much that her brain craves it when it is not on. The reward center of Jenny’s brain is frustrated when it does not get what it wants. And so all of the frustration comes pouring out in the form of tantrums, screaming and rage.

So even though Jenny is not “in danger,” you know the TV is sparking this cycle over and over. It is your job to stop the cycle.

Even in the face of all this ugly frustration.

Even in the face of the tantrum.

The beautiful thing about a properly held boundary is that, if it is held long enough, the brain eventually says, “Aha! So, the TV is not going on. No matter what.”

If we move the boundary around (give up in the face of the tantrum, get too stressed or tired to deal with the child, whatever), the brain doesn’t have a chance to learn where the boundary actually is.

So, to get an effective boundary set, here are some ground rules to consider:

1. Make your plan when you are not stressed. This is hugely important. Otherwise, you are reactively parenting, which will make you feel out of control, which will make you feel resentful which will . . . . You get the point.

2. Keep it reasonable for her age and development. A full hour of TV seems to be too much for Jenny. Listen to your instinct and see what the problems are in front of you. This can help you decide what is reasonable for your child.

3. Keep the boundary, especially in the face of the tantrum and screaming.

4. Do not allow the boundary to become a punishment. For instance, a good fence that separates the child from a dangerous cliff does not come out and attack the child when the child runs into it. It just stands there. Being a fence. Holding strong. You need to be the fence. Hold strong and resist the urge to attack.

5. In addition to holding strong, stay loving and softhearted with your child. Jenny’s brain wants the TV. The tantrums and yelling are not personal. Remember: She is a little girl. She is not a monster or a brat. All brains want what they want; most adults are just mature enough to manage that. So empathize, “It is hard to not watch the TV now . . .” or “I know, I love TV, too . . .” without giving up your boundary.

The more consistent you are about keeping your boundaries and not punishing Jenny, the sooner her brain will learn what is expected. And trust me, you will use this in your parenting life again and again.

Can you imagine the iPhone discussion?

8Send questions about parenting to meghan@ positivelyparenting.com.

Read a transcript of a recent live Q&A with Leahy at washingtonpost.com/advice . You can find previous columns at washingtonpost.com/onparenting. Her next chat is scheduled for Wednesday.