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  Psychology Dept.
  University of Idaho

In addition to that, as we see on slide three, if something occurred after the response and the behavior decreased, the procedure was called punishment and the thing that actually caused the decrease was called the punisher.

So as we show again in slide four, reinforcers always increase the behavior and punishers always decrease the behavior. And as I stated several times, there are no exceptions to that rule.

Now, as we talked about right at the end of last time, and as we see here in slide five, there were two types of reinforcers and punishers. Basically is it related to whether you added or removed something. If you added something followed a response, that was considered to be positive, and if you remove something followed that response, that was considered to be negative. So, as we saw from the last section, positive does not mean good and negative does not mean bad, they relate to whether you’re adding or removing something following some kind of response.

So let’s give an example of positive reinforcement. This is shown in slide six. If you add something following a response and the behavior increases, that is that is called positive reinforcement. The classic example of a goodie is a chocolate chip cookie. So when a little kid comes up and gives his mom a big hug and a kiss and he gets a chocolate chip cookie, guess what happens. Pretty soon the little kid is giving moms hugs and kisses all the time and getting lots and lots and lots of chocolate chip cookies. So in essence, mom is positively reinforcing her child with a chocolate chip cookie.

Now the key for Skinner and one of the major key points is how do you get the behavior to occur the first time? This is shown in slide seven. In essence, to get behavior to occur the first time, what we need to use is a procedure called shaping by success of approximations, or what is also called shaping. What you do is you reinforce successive approximations to a desired response, that is, to get a rat to bar press. So what is an example of getting a rat to bar press? Well when you throw the rat in the cage, often they’ll just wander around for an hour or so and won’t even press the bar at all. It doesn’t have any idea of what the bar is, it will just wander in there. So if you want to make the procedure go much faster, you give the rat reinforcement when it gets close to the bar, until then it finally touches the bar, and on and on. We’ll provide more detailed examples a little bit later.

Now the key point with shaping (as we see in slide eight), is this concept. That is, you must deprive the organism of what you wanted to reinforce it with. That is, if you have everything, lets say that you’re trying to bribe Bill Gates with money. Well you probably couldn’t do that because Bill Gates has 37 billion dollars or so, it’s pretty hard to bribe Bill Gates with $100. But on the other hand, you could deprive Bill Gates of food. This often is done (get an animal hungry) before placing the animal in a learning environment. An example of this is depriving the animal to 80% of it’s body weight When it’s hungry, it is much more willing to learn and do a lot more things.

Now kids work exactly the same way and so do adults. So what you want to do if you’re going to reinforce kids is deprive the kid of the reinforcer that you want to use. This is shown in slide nine. So, for example, if kids haven’t had chocolate chip cookies for a long time, and if you wanted to use those as reinforcers, they’re more likely to make the particular responses that you want.

In addition to that, what you want to do is use the chocolate chip cookies for small appropriate behaviors, and small approximate behaviors to the final desired response. For example lets say you want the kid to pick up all of its room and all of the clothes in its room. Well what you might start with is reinforcing them for when they just go into the room. When they’re doing that at a high steady rate, give them a reinforcer when they pick up a piece of clothing in the room, then two pieces of clothing and on and on until ultimately they have all their clothes picked up. Then you could also start working with the rest of the room as well. So in general, what you do is you reinforce for small, appropriate and small approximate behaviors to the ultimate final desired response. That is, a clean room. Gradually what you do is increase the amount of behavior that you want to reinforce before you give it the chocolate chip cookie.

Now in addition to regular shaping, there’s another type of shaping procedure and that is shown in slide 10 and called reverse shaping. Reverse shaping is a lot different from regular shaping. In essence, what you do is you start at the end response and reinforce it, then you take two steps backward and reinforce it, then three steps. The classic examples of reverse shaping an organism or reverse shaping procedure are shown in slide 11. That is, the Stuart Little, the mouse, and teaching a kid to tie their shoes.

Lets start with teaching the kid to tie their shoes first. If you’re going to use the reverse shaping procedure, you first look at all the things that a person has to do to tie their shoes. Well the first thing they have to do is cross one strings over and put one underneath. Then they have to make a loop, then they have to take the other string and wrap it around the loop, then pull it through, and then finally pull the two bows together. In reverse shaping, what you do first, is you start at the very end response. So you would have them pull the two bows together and when the kid can do that and do that well, then you do the next step, that is you wrap one string around the one. That is, you take one strand and wrap it around the loop and pull it through and then pull them both tight. So, in essence just putting the rope through the hole. Then making a bow and pulling them tight, and then wrapping it around the bow and then putting it through the hole, and then pulling it tight and on and on and on, until the kid goes all the way back to the original starting point of tying their shoes. That is, crossing the two strings over and putting one underneath the other. So in essence what you do is you start at the end response and you work back toward the beginning.

Stuart Little, the mouse, is another classic example. This technique is used a lot in animal training where you want an organism to do a lot of different things. Again, you start at the end response. Now Stuart Little was a mouse and what the director wanted the mouse to do was run around and do all sorts of things, go over tables, go under chairs, go behind doors and ultimately get up in his bed and lay down and go to sleep. Ok, so that’s exactly what we start with.

We start is at the end response, so what we do is we deprive Stuart Little of the food and put a little bit of food in Stuart Little’s bed and what does Stuart Little do, Stuart Little gets up in his bed and eats the food. Then what we do is we go one step further. We put Stuart Little on the far end of the counter, we put some food in his bed and then we let him go and he runs across the counter, gets up on his bed and eats the food and lays down. And then what we do is we go back one step further. We have a little ramp that Stuart Little needs to run up. So Stuart Little runs up the ramp, runs across the desk gets in his bed, and eats the food, and on and on and on, until we have Stuart Little at the other end of the house, running across the house, going over this and that, jumping up and down and running through, driving cars, whatever it may be, until finally he gets up and gets on his bed and lays down. This is a classic example of how to train an organism. Again, we start at the end response and work back to the beginning. In essence that gives a wide variety of different behaviors that the organism must go through.

So again, the key to shaping is depriving the organism. And whether you use a regular shaping procedure where you reinforce for behavior prior to the particular ultimate response or starting at the end response. The key is you reinforce closer and closer approximations to the final desired behavior.

Now the next concept that we want to talk about in relation to operant conditioning and in reinforcement relates to what we call negative reinforcement. This is shown in slide 12. Basically, in negative reinforcement what you do is you remove something following a response and the behavior increases. So again, what we’re doing is removing something, (ala the negative stimulus), and the behavior increase. So, removing something following the response and causing the behavior to go up is negative reinforcement.

Now there are two types of negative reinforcement. The first type is shown in slide 13 and is called escape learning and it’s really straightforward and simple. If you escape from something that’s aversive, the next time that you are in the same situation, you will make the same response. So how does that work. Well, let’s use the classic example in relation to spousal abuse. This example is shown in slide 14.

Let’s say that the husband and wife are having an argument in the kitchen, and the wife is yelling and really yelling loud at her husband and on and on and on. Now, that is an extremely aversive stimulus to the husband. So, the husband smacks the wife. As a result of that, the wife stops yelling immediately. Consequently because the husband has removed something that’s aversive to him, in the next situation he will do the same thing again. That is, the husband has been negatively reinforced. He stopped the wife from yelling and so in the next time, when the husband’s in a similar situation, the husband will hit the spouse again. So, if we concentrate only on feelings and nothing else (No I won’t do it, no I won’t do it, I’ll control my temper, on and on and on) it won’t work. We have to control the behavior because the husband was reinforced for a particular behavior and negative reinforcements are very, very powerful.

The second example of negative reinforcing stimuli and negative reinforcement is what we call avoidance and that is shown beginning on slide 15. To avoid something aversive, you basically are avoiding something aversive. The classic example goes something like this and is shown in slide 16. You have a little kid in a candy store, and the little kid wants a candy bar. So the kid is by the counter and it’s saying “Mommy can I have a candy bar, I want a candy bar, please can I have a candy bar,” on and on. “I want a candy bar.” When mom says, “No you can’t have a candy bar,” kid starts to get more persistent. It starts to get more obnoxious, “I want a candy bar, give me a candy bar, I want a candy bar, please give me a candy bar, please, please, please.” As a result, the parent becomes extremely embarrassed and upset and it gives the kid a candy bar. As a result, the kid stops yelling, and as a result of that, the parent is negatively reinforced. They escape from the aversive stimulus. There is no more yelling. So, what will happen the next time when the kid is starting to yell in the aisle? What’s the parent going to do? It’s going to stuff a candy bar in its mouth.

Now how does that relate to an avoidance type of situation. Well instead of waiting for the kid to start yelling about having a candy bar when it gets into the store or right by the aisle, the next time the parent comes up to the counter it just gives the kid the candy bar. So, what the parent does is avoid the major scene that it’s had before.

Now you need to know (as we see in slide 17) that the kid has been positively reinforced for it’s behavior. So what does the kid learn from all of this. When I make some particular kind of response, ala yell and scream, in the store, I get what I want, I get the candy bar. So what are you going to see with the kid’s behavior over time in the store? Every time it wants something, it’s gonna start yelling and screaming in the store because it has been positively reinforced for it’s behavior while the parent has been negatively reinforced for their behavior.

So this section, we again have reviewed a variety of aspects of reinforcement. In the next section, we’re going to continue with this discussion and provide more information and discuss some variables that affect reinforcement.