Does spanking affect a child's brain development?

What five decades of research found

In 2016, the researchers Gershoff and Grogan-Kaylor pooled five decades of research on 160,927 children. Spanking, meaning an open-handed hit on the bottom or limbs, was linked to worse outcomes on 13 of 17 measures and better outcomes on none. The worse outcomes included more defiance, more aggression, more mental health problems and more thinking difficulties. Adults who'd been spanked were more likely to support hitting their own children.

A 2021 review in The Lancet looked at 69 long-term studies that followed children over time. Physical punishment predicted increases in behavior problems and wasn't linked to any good outcome, with some signs that more spanking went with more problems.

An honest note on the evidence: nobody can run a randomized trial that assigns children to be hit, for obvious ethical reasons. So the proof comes from long-term and other careful studies. Their findings have been unusually consistent, and they all point the same way.

What a smack does to a young brain in the moment

The part of the brain that runs planning, waiting and "stop," the prefrontal cortex, is one of the last parts to mature. A toddler or preschooler has big feelings and very weak brakes. When she melts down or lashes out, her alarm system is already firing.

Children build self-control through co-regulation first. Your calm voice, slow breathing and steady presence do the job her brain can't do yet, and over hundreds of repeats she learns to do it herself. A smack does the opposite. It floods an already-flooded brain with fear. The American Academy of Pediatrics (AAP) notes that hitting, yelling at or shaming a child can raise stress hormones.

It also teaches a lesson you didn't intend: big people hit when they're upset. The behavior may stop for a minute. The child hasn't learned to stop herself.

The big reviews measured behavior, mental health and thinking skills over years. They point to the same thing: hitting doesn't give a child's growing brain what it needs to learn self-control.

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What pediatricians and the WHO say

The AAP's 2018 policy on discipline advises against spanking. In one study it cites, children spanked more than twice a month at age 3 were more aggressive at age 5. The AAP adds that harsh yelling and shaming carry their own risks.

The World Health Organization estimates that about 1.2 billion children aged 0 to 18 face physical punishment at home each year. It says this kind of punishment "harms children's physical and mental health" and calls it "a violation of children's rights."

What works instead

The AAP recommends rewarding good behavior, setting expectations ahead of time, redirecting, and being consistent. In practice, for a toddler or preschooler:

• "I won't let you." Calm, firm, and it says what you'll do. "I won't let you hit. Hitting hurts." Then gently block or move her.
• Time-in. Move her away from the trouble and stay close until the storm passes. Name the feeling once. Teach in one short line afterward. Our page on time-out vs. time-in walks through it, and notes that a brief, calm time-out is fine too.
• Limits set before the moment. "Two more slides, then we go." Keep it short and follow through.
• Choices and when/then. "Climb in or should I lift you?" "When your shoes are on, then we go outside."
• Routines. Toddlers fight less about what happens the same way every day: bath, pajamas, two books, song, lights. Fewer battles means fewer moments when you're tempted to hit.
• Words for feelings. A child who can say "I'm mad!" has less need to hit it. See how to handle toddler tantrums for scripts.

All feelings are allowed. Not all behavior is. That one line covers most of discipline at this age.

If you've spanked, or you were spanked

If you were spanked as a child, you don't have to judge your parents, or yourself. You can simply choose differently from today.

If you've spanked your own child, the same is true. Children's brains keep building for years, and relationships bend without breaking when the breaks get repaired. A repair takes under a minute: calm yourself, get low, name what you did ("I hit you. That was wrong"), own it without blaming her, reconnect with a hug, then go back to the limit kindly. Our page on what to do after you yell at your toddler has the full version. You're also teaching her how to say sorry and mean it.

Hard moments often come when you're exhausted and out of patience. If you feel close to hitting, step away for 10 slow breaths if your child is safe. Build in help where you can, and tell your doctor if stress or low mood is hanging on. That's care for your child too.

Go deeper

Grow a Genius

In the book: Chapter 21: Toddler Psychology

The chapter explains why spanking backfires and gives you the replacement toolkit: time-in, calm limits, emotion coaching and the one-minute repair, with scripts for the hardest everyday moments.

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