Hi, I'm Michael Corayer and this is Psych Exam Review. In this video I want to go into a little more detail on B. F. Skinner's work on operant
conditioning. First we'll look at a device that Skinner created called an operant box, although other people have
referred to as a "Skinner box". So what an operant box was was
a box
that allowed Skinner to track behavior over time.
Inside this box we'll have
some animal, so here's a rat
inside of this operant box.
The box
contains a section
where food can be dropped into the box. So we have a rat in here who's hungry and we know he's hungry because the animals that Skinner
used, the rats and the pigeons were kept a little bit underweight about 3/4 of their normal weight.
This would ensure that they're always hungry, therefore they're always motivated to learn. We'll come back to this idea when we talk about
motivation later.
So we have this food dispenser here and so
the food can be dropped into this little tray here so the rat can eat and this happens when the rat does some specified behavior.
We can have some lever here. Let's say every time the rat presses on this lever then food
will be dropped in here and he'll get the reward, he'll get the reinforcement.
Or it could be a disc that a pigeon pecks at. I'll put a link in the video description where you can see a video of Skinner working with some
pigeons and you can see these operant boxes in action. The other part of the box was connected to a device over here which was
essentially like a pen and a sheet of paper.
What would happen is the pen would move, over time, to the right so that would tell us about time passing and then each time the
animal did the behavior like press the lever or peck at the disc, the pen would click up.
That would tell us that a behavior had occurred. Over time the pen would be drawing a line on the paper that would tell us the total number of
lever presses over some certain amount of time. This allowed Skinner to keep track
of different schedules of reinforcement and how they influenced behavior. So he could compare something like
continuous reinforcement
where he reinforces the animal every time that the lever is pressed,
to
some other schedule that would involve intermittent reinforcement and that refers to
only rewarding the animal at certain times for a certain number of lever presses or over a certain period of time.
Now we can look at some of the more detailed schedules of reinforcement that Skinner used to
to track of how they influenced the behavior from the animal.
Le's look at some of these different ways he could provide intermittent reinforcement.
OK the first thing he could do was he could change the ratio between how many times do you have to press the lever to how much food
do you get. So you have to press the lever 5 times to get one food pellet or you have to press the lever 3 times.
This would be a fixed
ratio schedule.
That means there's some ratio between
level presses and rewards. So you have some X number of letterpress is
this gonna get you one
food pellet.
It could be five lever presses or it could be one lever press. Continuous reinforcement would be one lever press gets one food pellet every
time. The important point is that it's fixed. It's predictable, the animal knows "if I press five times, I get a food pellet".
A human example for this
would be something like a vending machine.
It's supposed to be predictable. If you put in a dollar and you press this button then you get a soda. It works that way every time.
So that's an example of a fixed-ratio schedule.
In contrast, we could have a variable ratio schedule.
So in a variable ratio
we don't know how many presses
will lead to the food pellet.
It's unpredictable
and it's variable, meaning it's always changing.
That's what makes it unpredictable. Sometimes you press three times and you get a food pellet. Then you press 10 times before you a food
pellet and then you press once and you get a food pellet. So it's a ratio that's always changing. So it's unpredictable. A human
example for this would be a slot machine.
You don't know how many times you have to pull the lever to get the reward.
And it changes, when you win you could win again immediately or you could play 20 more times before you win, right? So this is going to
change the rate of behavior that you're going to have compared to say a vending machine.
Now the other thing that Skinner could change rather than changing the ratio between how many
lever presses get food, he could change the time interval.
So the next two schedules will involve changing the time interval.
One thing he did do was have a fixed interval.
In a fixed interval schedule, this means that
X amount of time
allows you to get one food pellet. In other words, a food pellet is only available once every 2 minutes. You still have to do the
behavior, you still have to press the lever in order to get it. But once you get it, you have to wait until another 2 minutes has passed before
you can get the next one. So we have some set amount of time that's fixed and you're allowed to get a certain amount of reward during that
certain interval of time. What would be a human example of this? Well, you have a regular paycheck.
If you show up and do your job, if you press the lever, then every two weeks you get a paycheck.
Or every month or something like that. It's not the case that if you work really hard you get two paychecks two days in row. It doesn't work that
way. You have to wait, you can only get one paycheck every two weeks.
But you still also have to do your job, right? Just like the animal here still has to press the lever every 2 minutes or something to get that
food pellet. Pressing it more isn't going to get more food pellets until another 2 minutes has passed. So that's a fixed-interval pattern.
Lastly, we have a
you can probably guess, a variable
interval.
So in this case
we have some unknown unit of time that's variable that's always changing
is associated with getting the
food pellet.
Here you don't know how much time passes before the next one is available.
Again, you still have to press the lever to get it but you don't know how long to wait before the next will be available.
So what's this going to do to your behavior? What's a human example of this? A human example would be a
pop quiz. Let's say that
in a certain class you always had pop quizzes for your tests and you never knew when they were coming. You could have two days in a row
where you have a quiz or it could be 2 weeks in between them and it changes every time.
How would this influence your behavior?
You'd probably study a little bit every day to try to be prepared for this pop quiz that may or may not happen.
So here the unpredictable part is how much time will pass before the next one.
OK so now that we have a general idea of these four different patterns
we can think about, what would the pen connected to the operant box draw? What would that line look
like for each of these different schedules? This is what Skinner looked at.
If we imagine one of these charts here
we have time over here and then this is going to show the cumulative
responses, the total number of behaviors. Each time the lever is pressed the pen clicks up and so it's adding up over time the total
number of behaviors. Let's look through each of these schedules and see what their line would look like.
If we did this fixed ratio every certain number of lever presses will get a food pellet. Let's imagine we're looking at our rat here
he's gonna press it, let's say it's five times, so he's going to quickly press it five times and then he stops and eats the food pellet and then
he's going to press it five more times then he eats his food pellet, then he presses it five more times.
So we're going to get a line looking something
like this. We get five behaviors in a row then eat the food pellet, five in a row, five in a row like this.
Now we can compare that to
our variable ratio.
So what's going to happen in a variable ratio? Well he's going to press it rapidly because he doesn't know which press is going to deliver the
reward and it's always changing. So he's going to press it rapidly. Let's say he presses it 10 times then he gets a reward.
Then he presses it three times and he gets a reward but then he has to press it 15 more times. So he's going to do that very rapidly. He's
just going to sit there pressing pressing pressing, hoping the next press is going to be the one that delivers the reward.
So in the variable ratio schedule you get a very rapid response.
The animal will sit there press press press, hoping to get to that. It's kinda similar to what you see with someone playing a slot machine.
You never see anyone sitting at a vending machine pouring money in and pressing buttons but in slot machines you see that all the
time. Very rapid, the idea is the next one could be the reward so you want to get to it as quickly as possible.
Another difference here is that
this variable ratio schedule is very resistant to extinction.
Because what happens if you turn off the food delivery
the animals going to keep pressing that lever rapidly because the animal doesn't know that the food has stopped. It just thinks "now I need
to press it 20 times or maybe it's 21 or maybe it's 22" and they'll keep pressing the lever
and they won't learn that it doesn't work anymore. In comparison, a fixed-ratio
extinction occurs more rapidly. You can remember this if you just think of the difference between a vending machine and a slot
machine. If a vending machine breaks, it's not delivering food, how many times are you going to play? How many times are you going to do
the behavior before you stop? Put your money in, press the button, no soda comes out. Put your money in, press the button, no soda
comes out. Probably after 2 or 3 you're going to give up. But a slot machine let's say is not actually going to ever pay off, how many times
might you play it before you figure that out? You might play it 20 times and just think you're having a streak of bad luck.
The variable ratio is going to be more resistant to extinction. Now let's look at the time intervals. If we have a fixed interval, what's that
going to look like? Every certain amount of time you can get a food pellet, then you have to wait for that time
before you can get another one.
So we press the button, press the lever, then we get a food pellet,
and then there's no point in pressing for awhile. There's going to be another minute or two before
you say ok, "I think it's been", let's say the interval is every 2 minutes, "I think it's been about 2 minutes I'm going to start pressing the
lever again to make sure and then "I just got it, now I don't have to do anything for a while" and then "it's been 2 minutes, press it again".
So you're going to get this, what's called a scalloped pattern.
where you have these rest periods followed by a rapid increase in behavior followed by rest, followed by rapid increase
followed by rest, like this.
You can think about how this would work in the case of your studying. If you have a fixed time
interval between your exams. Let's say you have a big exam ever month,
what's your study going to look like?
Exam's coming up, study study study! Ok, just had the exam, play video games,
oh the exam's coming up in another day, study study study, then take a break.
You're going to see this same sort of pattern.
What's your study going to look like if you never know when the test is coming. You could have two tests in a row or you could have tests
two weeks apart. How are you going to study that way? You're not going to cram every night. What you're probably going to do is have a nice
slow steady rate of response where you're going to study a little bit every day. That's what happens with this variable interval. Imagine if it
was paying off at an unpredictable time. You'd press the lever every once in a while to just check. Can I get some food now? No, alright,
wait a little bit, try again, no, try again. You're going to have this slow and steady rate of behavior and that's what Skinner found in this
variable interval schedule. Ok, I want to quickly describe one other thing that Skinner did
where he just rewarded the animals at random.
By this I mean it wasn't the ratio that was changing, it wasn't the time that was changing. It was random in that they didn't even have to
press any levers. They didn't have to do anything, he just dropped food into their cage at random times. It was unpredictable. You
might think that the animal would just sit there and wait for the food to magically rain down from the sky. If you're a pigeon sitting in there
and food just drops in, you eat it, you don't have to do anything, just wait around for the next
piece of food to drop. But that's not what happened. What Skinner found was
evidence for superstitious behavior, or what he said was superstitious behavior in these pigeons.
What this meant was the pigeons would happen to be doing something before the
reward came. They'd happen to be turning their head to the left and food drops in.
They happen to turn their head to the left again and food drops in again. They think "I know what to do! Turn my head to the left and I'll get
food!" so they keep turning their head to the left, they end up spinning in circles because they thought that was what was causing the
food to drop into the cage. Or the pigeon next to him would be lifting his foot as the food dropped in
and so he'd think "they must want me to keep lifting my foot" and food drops in again and so he'd sit there lifting his foot over and over again
or flapping one of his wings or something. He'd end up with these superstitious behaviors that
were purely chance but that the animals thought were being rewarded.
We can draw a human comparison if we think about you happen to wear a new pair of socks and you just so happen to hit a home run
at your game that day and you think "these are my lucky baseball socks".
Then you happen to be wearing them again and you just so happen to hit a home run again. It's this sort of random chance
but you become convinced that these are your lucky socks. Skinner would say that's because of this random nature of the reinforcement and
this chance occurrence that it's paired with something else like your lucky socks and you become convinced that that's the reason for
the outcome that you're getting.
Ok so in the next video we'll look a little more detail on how we can use conditioning to get more complex behaviors.
So this was operant boxes and these schedules of reinforcement. I hope you found this helpful
if so, please like the video and subscribe to the channel for more. Thanks for watching!