Adrian Peterson, the NFL running back, has been indicted for injuring his 4-year-old son. According to sources in law enforcement, Peterson used a tree branch to discipline the boy, leaving cuts and bruises.

Peterson’s lawyer says his client meant no harm. “Adrian is a loving father who used his judgment as a parent to discipline his son,” says the attorney. “He used the same kind of discipline with his child that he experienced as a child growing up in East Texas.”

Of course he did. I know all about Peterson’s world. I grew up in East Texas, about 40 miles from where he struck his son. I was never hit with what Peterson calls a “switch.” My parents didn’t believe in corporal punishment. But the public schools did. That’s where I was paddled.

My public elementary school began every day with a Christian prayer over the loudspeaker. By sixth grade, kids were getting paddled. One teacher was so well known for her corporal punishment that boys made paddles for her in wood shop. She hung the paddles in her classroom. They had holes drilled through them for extra velocity and bite.

I can tell you what kids learn from being hit. They learn about hitting, and about you.

I wasn’t paddled until junior high. I couldn’t tell you what my offense was. The principal offered me a choice between detention and “swats.” The detention would have taken hours. The swats would be over in seconds. It was a no-brainer. I stood, as instructed, with my hands against a desk in the principal’s office. I don’t remember what I was hit with, how many times, or whether the principal did the deed. I wasn’t looking.

Did he say anything while it happened? What was he trying to teach me? I have no idea. When somebody’s hitting you, what you think about is being hit. And that’s what you remember afterward. Every child absorbs this differently. Some kids think they deserve it. (Presumably this includes the boys who made paddles in wood shop.) Others get upset. Others, like me, feel nothing but contempt. But all of us think about the hitting. We remember the punishment, not the crime.

That shouldn’t surprise anyone who has looked at research on child development, or who has reflected on parental experience. You start out thinking that you’re going to teach your child a lesson. You talk, or you gesture, or you spank, or you withhold. You’re trying to convey a message. But your kid doesn’t focus on the message. He focuses on you. What he experiences is the talking, the gesturing, the spanking, or the withholding. That’s what he learns. You’re not an instructor. You’re a model.

Study after study documents this pattern. It suffuses every interaction between adults and children: love, cooperation, exploitation, violence. The strongest predictor of whether a child thinks it’s OK to hit kids, and whether he’ll grow up to do so, is how often he’s been disciplined that way. Light spanking isn’t as bad as wielding a tree branch. But it’s part of the continuum. Researchers call this the “hidden curriculum”: Corporal punishment teaches itself.

Peterson thought he was teaching the opposite. According to reports, he was punishing his son for pushing and scratching another child. He says he explained this to the boy. “Anytime I spank my kids, I talk to them before, let them know what they did, and of course after,” he told investigators.

But when you hit a child for hitting another child, the hitting does all the talking. That’s the upshot of a recent study of more than 100 children and their parents. Every parent who approved of spanking a child for hitting a sibling passed this belief on to their kids. And 79 percent of kids who came from homes with lots of spanking said they’d hit a sibling for trying to watch a different TV show — almost the same scenario that led to Peterson’s beating of his son. According to the researchers, “Not one child from a no-spanking home chose to resolve these conflicts by hitting.” The kids absorbed the model, not the lecture.

Peterson isn’t a monster. Nor are the millions of parents who spank their children every day. Raising kids can be frustrating. You try so hard to make them behave, but they just don’t listen. You hope a spanking will get their attention, and it does. But they’re not listening to your words. They’re listening to the switch, or the belt, or the sting of your palm. With every blow, you’re losing contact. Remember that the next time you raise your hand.

William Saletan writes about politics, science, technology and other stuff for Slate. He’s the author of “Bearing Right.” This column appeared on Slate.com, an online current affairs and culture magazine owned by The Washington Post.