The 4 Functions of Behavior in Applied Behavior Analysis

Most people in the ABA community know that there are 4 functions of behavior. However, we usually only hear and talk about 3 of the functions of behavior. The fourth function that usually isn’t discussed is behaviors related to pain or stress, which in technical terms is called automatic negative reinforcement. Today, I’m breaking down the 4 functions of behavior in an easy to understand format and discuss in detail the all-important forgotten function.

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Function 1: Socially Mediated Positive Reinforcement

So we have 4 functions of behavior and 1 function is the child cries or hits, bites, kicks, or screams. So let’s just say child bites his hand. The first function is what we call socially mediated positive reinforcement, which means in the past when he’s bitten his hand it has meant that something good happens. That he has received positive reinforcement that has followed biting his hand. This might be that the child bites his hands because he wants something and in the past, he’s gotten it.

So this could be that the child wants candy in the candy aisle at the grocery store. That’s the first function, socially mediated positive reinforcement. Socially mediated means people are involved and positive means he’s given the candy.

Function 2: Socially Mediated Negative Reinforcement

Then we have socially mediated negative reinforcement. We’re talking about the same child, Johnny, and he bites his hand when he doesn’t want to do something, to get out of something.

So it’s time to take a bath, he bites his hand, and then mom says, well, you know what? He got a bath last night. He’s not that dirty. Let’s not do it. And now Johnny has learned, okay, so I bite my hand to get things. I bite my hand to get out of things. That’s socially mediated negative reinforcement. So both of those functions, people are involved.

We tend to see those functions a lot in the classroom setting and home settings. This isn’t just for children with autism, this is children or adults. These are functions that have been proven as to why behaviors occur. So we have the 2 socially mediated functions, positive and negative reinforcement.

Function 3: Automatic Positive Reinforcement

Then we have 2 additional functions that are called automatic, which means people don’t have to be involved. The adults don’t have to be in the picture. They can be included in the environment, but it’s not that they are adding or taking away.

The third function is automatic positive reinforcement. It tends to feel good or sound good to the student or the child and Johnny may bite his hand just to stimulate himself. I know that sounds weird because you would think that that would cause pain. Let’s just say he’s not really biting on his hands. He’s biting the cuticles of his fingers and he’s biting them kind of raw. He’s doing that because he likes the way it feels potentially.

Let’s use another example, like self-stimulatory behavior where the child might be rocking or might be verbal stimming or making noises. Because either way, this positive reinforcement, this stimming or this biting on the cuticles or this rocking, some headbanging may occur, is because the child doesn’t have the language, doesn’t have the play skills and other skills that are needed to occupy his mind.

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Function 4: Automatic Negative Reinforcement

The last function is the automatic negative reinforcement, which is pain attenuation. So a child might bite his hand if he’s in pain or stress. This is what happened to Lucas. When he was 13 or 14 years old, he started to bite his hand and he also at that point was able to tell us he had a headache. So he’s biting his hand and he was saying head hurts and it was like stabbing pain that I think the biting actually drew his attention to the pain in his hand and then the headache miraculously went away even before I could run downstairs to get Motrin. But why would that be? In early August, I went to The National Autism Conference at Penn State University and I’ve been there many times.

It’s a great conference, always in early August, and it’s always great. They do live-streaming and some of the 3-hour lectures are recorded. I saw Dr. Tim Vollmer there who’s an expert in these 4 functions of behavior. He was talking a decent amount about automatic positive and negative reinforcement. Check out the show notes from my podcast with Dr. Tim Vollmer so that you can watch the lecture by him if you are interested. I think it’s a fascinating lecture. I told him that I was interested in studies on automatic negative reinforcement, the pain attenuation because I have a strong interest in this.

I know that over time it’s been proven that Lucas’s self-injurious behavior and aggression were related to pain and distress. When I asked Dr. Tim Vollmer about the studies on automatic negative reinforcement, he said right away that there are 0 studies on automatic negative reinforcement and he also added later in the lecture that all animals like monkeys and birds and rats, they bite on things when they’re in distress, when they’re in pain or stressed. He hypothesizes that some of the biting behavior, whether it be biting on your hand or biting others, could definitely indicate that the child is in some kind of distress and possibly pain.

He also added that in the past, before anesthesia, that humans were given a towel to bite on. My dad said like in the cowboy movies that to get a bullet out, they’d often show a person biting on a towel. I’m also trying to tell behavior analysts, we can’t just use bite guards and use helmets if the kids are having self-injurious behavior. We really need to get to the bottom of this and we are, by our ethical code, behavior analysts need to have these medical conditions ruled out before we go treating problem behaviors with a keeping the demand on procedure or any kinds of behavioral procedures, we need to figure out what’s going on medically.

It’s really impossible when children are either not speaking at all or have limited language. If you want more content like this, check out the podcast at You’ll also be able to listen to the full episode on the functions of behavior there too. Wherever you’re watching/reading this, I’d love it if you would leave me a comment, give me a thumbs up, share this video/article with others who may benefit. And for more information, you can attend a free online workshop at and I’ll see you right here next week.

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