When Minnesota running back Adrian Peterson was arrested Saturday morning for hitting his 4-year-old son with a switch, the reaction was mixed. Some were appalled by his actions. Many others expressed solidarity with Peterson. “Whippingwe do that all the time,” former NBA star Charles Barkley said Sunday. “Every black parent in the South is going to be in jail under those circumstances.” He's not the only one who thinks that way. As Harry Enten at FiveThirtyEight found, approval of spanking as a disciplinary measure has fallen over time, but is still higher than 60 percent.

What do psychologists and medical researchers think about it? How does corporal punishment affect children’s well-being? To help answer those questions, we decided to ask an expert. Stacy Drury, a well-respected professor of psychiatry and behavioral science at Tulane University. researches early childhood development with a focus on improving long-term health outcomes in children. We spoke Tuesday about Peterson, spanking and child abuse.

Danny Vinik: Adrian Peterson’s comments seem like a good representation of how many people think of corporal punishment. Peterson said, “I am not a perfect parent, but I am, without a doubt, not a child abuser. I am someone that disciplined his child and did not intend to cause him any injury.” Is Adrian Peterson a child abuser?

Stacy Drury: Part of that question is a legal definition. That stems from the definition across each state about what child abuse is. Each state defines its own definition of what is and is not child abuse. Almost universally, the leaving of visible marks is one of the criteria for child abuse. Child abuse is a legal definition and certainly not something that I can speak to, but that being said, that is one of the main criteria that seems to cross all of the states in terms of how they define child abuse. Leaving physical marks, lacerations or anything that lasts more than a couple of minutes is part of the definition of what child abuse is.

I think that part of his statement that is so important, so critical, is saying that he went beyond what he intended to do. That is the crux of why there are such strong policy statements from those in the American Academy of Pediatrics and the American Academy of Child and Adolescent Psychiatry saying corporal punishment is not in the best interest of the child or the parent-child relationship. There is a significant number of parents who when they talk about physical discipline of their children, report similar things to what he [Peterson] reported which was that it went beyond his initial intentions: I didn’t mean to leave lacerations on my child.

DV: That seems to be a common reaction from people who don’t see anything wrong with corporal punishment. The spanking wasn’t intended to hurt the child. It was intended to change their behavior.

SD: Along those lines, what I can tell you, is that the goal of discipline, which actually comes from the Latin root meaning “to teach,” is to change behavior. And physical discipline across many, many, many studies is ineffective at changing behavior and it’s ineffective for many reasons. The first is that it doesn’t provide children with an alternative. They don’t know what else they could have done when they are being physically abused, like when they’re being physically hit or punished. One of the goals of discipline is to have them understand what happened to make sure that behavior doesn’t occur again.

The second is that when corporal punishment is utilized, it creates an emotional state of fear in the child. Physical pain leads children to fear things and when we are afraid, we don’t learn well. We don’t respond well. And if we learning anything, we learn to respond to that behavior with fear. And the third thing that corporal punishment actually teaches children is that aggression is an acceptable method of problem solving.

DV: What we think about the effects of corporal punishment, should we think of them any differently if there was disciplinary intent versus non-disciplinary? Or should we not think of these different actions that impact a child’s life?

SD: That’s a really tricky question. I think that what I would tell you is that physical maltreatment against children without a goal of any discipline or behavior modification is incredibly damaging to children. It has negative effects across mental health and physical health. That has been very well established.

When we are talking about the use of physical approaches or corporal punishment to discipline, are they different? I think the problem is that it’s a very grey line. There is good evidence individuals who use physical discipline are more likely to actually end up using physical abuse or getting to the point where there’s physical abuse. There’s a progression and that is absolutely more common in parents of children that use physical discipline approaches. There’s an increased risk that you will end up maltreating your child down the line if you end up using physical discipline strategies.

I just want to clarify that there are clear differences at least in the data between spanking and discipline that goes beyond spanking. Spanking meaning using the hand to slap the child’s buttocks or part of the body [and] doesn’t leave marks for more than a minute. I think there’s a greater amount of controversy on that ground, but clearly physical discipline that leaves marks or utilizes tools are not associated with anything good. The separation of maltreatment and violence against children done with a discipline strategy versus without is not as clear as we would like it to be. Unfortunately, when many parents use corporal punishment they do exactly what is described in this case, which is “I lost control.” Using control is not effective discipline. If you’re leaving visible marks on your child, even if you started out with the goal of discipline, you really crossed that line.

DV: One of the other things that Adrian Peterson said is that “I always believed that the way my parents disciplined me has a great deal to do with the success I enjoyed as a man.” This is a comment I’ve heard frequently. I’m sure it varies on a case-by-case basis, but is there any evidence that this is true?

SD: There’s actually solid evidence that if you were physically disciplined as a child, you’re much more likely to use physical discipline as a parent. That is clear. There is evidence that effective discipline—effective discipline meaning discipline that is designed to teach, done by supportive parents, and that is done in a way that has a more positive reinforcement versus negative reinforcement—is associated with increased self-esteem, increased peer-relationships, better outcomes for children across the board. Physical discipline doesn’t have to be a part of that. It really is about the supportive parent relationship. It’s about providing the appropriate outlets or alternative choices for negative behavior. And it’s about the different balance between positive and negative reinforcement that end up having children turn out really well. So while he may have had parents that utilized physical discipline approaches, my bet is that the discipline involved way more than that and that they were supportive and provided structure, sent him to school and monitored his behavior. All of that is why he turned out as well as he did. That does not link to the fact that he might’ve been spanked as a child for negative behavior.

I’ll also say that there is a developmental component to this which is that with young children and toddlers, the impact of physical discipline strategies on them is greater, because their relationship and reliance on their parents is bigger. The parents are supposed to be supportive and protective environment for children in which to explore the outside word. And when that supportive and protective environment actually causes you pain early on, it’s a much greater impact than when you’re older.

DV: What are the long-term effects on kids who receive corporal punishment?

SD: Increased risk for physical abuse later on other people. Increased externalizing behaviors,: aggression, oppositional behavior in school and academic settings, but also with their own peers. Also we see increased risks for anxiety [and] other types of mental illness. There have been some studies that have looked at decreased language in children that have been exposed to corporal punishment. There have been some long-term studies in other countries showing that there is a clear relationship between physical discipline strategies and negative outcomes across culture. So, this isn’t a U.S. thing. It’s something that has been seen in many other countries.

Unfortunately, the U.S. is one of the few countries that hasn’t outlawed it. There are studies now in Finland where they look at the change in rate of alcoholism and child murders and many other things 28 years after they outlaw physical discipline. There’s longitudinal data suggesting that there is tremendous public health policy implications for outlawing it.

DV: There probably isn’t political support for outlawing corporal punishment in the U.S. What else can the government do to nudge people away from this practice?

SD: The part that I think is so frustrating is that we have such effective, evidence-based parenting interventions out there. One of the challenges is often parents think that they have no other option, that this is the only way they can get their point across. I’ve heard that many times. Fortunately, we have great evidence-based treatments, particularly for little kids. Parent-child interaction therapy is an excellent public behavior parenting approach that teaches parents different disciplinary strategies. It’s not that we don’t want parents to feel they can effectively discipline their children. We just know there are effective ways to do it.

So, from a government standpoint, a bit earlier my son said something striking: We outlaw whipping prisoners and yet we think it’s okay for parents to whip their kids. In this case, what I would say the government can do is to really focus on programs that are evidence-based. Build that into greater support for governmental health services at every level. Give parents access to better strategies and really provide support for particularly high-risk families and families with young children.

DV: It seems that reaction to Peterson’s arrest has been relatively cavalier, particularly when compared to Ray Rice’s domestic violence incident. Everyone rightfully condemned Rice’s actions immediately. That should happen with Peterson’s actions as well, but it hasn’t. That disparity seems like a problem in and of itself.

SD: I wonder if people remember that physical discipline and they ascribe much to it. They miss all the other positive and supportive actions that their parents provided outside of the physical discipline. Many people in my generation have that moment where they remember getting and we’re like, “Well, that’s why we turned out OK.” But really what happened was we had really supportive parents who, in a moment of really high-level fear and anxiety for the safety of their child, made a mistake in their parenting. The many, many other instances where the parents demonstrated parental warmth and positive discipline strategies actually happened. If you retrospectively think about all the other approaches to discipline that parents used besides physical strategies, then it’s probably a lot more than people think.

Anybody who has been a parent has had that moment where things got out of control when they were frustrated [and] upset and they utilized a strategy that they didn’t want to use. If we say that this is bad, many people will be worried that they’ve done something really horrible. One of the things we want to emphasize is that being a parent is incredibly challenging. At every age, we are faced with stresses and challenges to being a parent and to admit that there are times when we are not perfect is OK. But also to know that when were about to get to that point, we need to call in the cavalry, to tag a number family member or a spouse or a partner—someone who can keep us from using discipline strategies that aren’t effective when we are upset or agitated.

This interview has been edited and condensed for clarity.