Professor Paul Bloom:
I actually want to begin by going back to Freud and hitting
a couple of loose ends. There was a point in my lecture
on Wednesday where I skipped over some parts.
I said, “We don’t have time for this” and I just whipped past
it. And I couldn’t sleep over the
weekend. I’ve been tormented.
I shouldn’t have skipped that and I want to hit–Let me tell
you why I skipped it. The discussion I skipped was
the discussion of why we would have an unconscious at all.
So, I was talking about the scientifically respectable ideas
of Freud and I want to talk about some new ideas about why
there could be an unconscious. Now, the reason why I skipped
it is I’m not sure this is the best way to look at the
question. As we will learn throughout the
course, by far the vast majority of what our brains do,
the vast majority of what our minds do, is unconscious and
we’re unaware of it. So the right question to ask
may not be, “Why are some things unconscious?”
but rather, why is this tiny subset of mental life–why is
this conscious? On the other hand,
these claims about the utility of unconsciousness,
I think, are provocative and interesting.
So I just wanted to quickly share them with you.
So, the question is, from an evolutionary
standpoint, “Why would an unconscious evolve?”
And an answer that some psychologists and biologists
have given is deception. So, most animals do some
deception. And deception defined broadly
is simply to act or be in some way that fools others into
believing or thinking or responding to something that’s
false. There’s physical examples of
deception. When threatened,
chimpanzees–their hair stands up on end and that makes them
look bigger to fool others to thinking they’re more dangerous
than they are. There’s an angler fish at the
bottom of the ocean that has a rod sticking up from the top of
its head with a lure to capture other fish – to fool them in
thinking that this is something edible and then to themselves be
devoured. But humans, primates in general
but particularly humans, are masters of deception.
We use our minds and our behaviors and our actions
continually to try to trick people into believing what’s not
true. We try to trick people,
for instance, into believing that we’re
tougher, smarter, sexier, more reliable,
more trustworthy and so on, than we really are.
And a large part of social psychology concerns the way in
which we present ourselves to other people so as to make the
maximally positive impression even when that impression isn’t
true. At the same time,
though, we’ve also evolved very good lie detection mechanisms.
So not only is there evolutionary pressure for me to
lie to you, for me to persuade you for instance,
that if we’re going to have a–if you are threatening me
don’t threaten me, I am not the sort of man you
could screw around with. But there’s evolutionary
pressure for you to look and say, “No.
You are the sort of man you could screw around with.
I can tell.” So how do you become a good
liar? And here’s where the
unconscious comes in. The hypothesis is:
the best lies are lies we tell ourselves.
You’re a better liar, more generally,
if you believe the lie that you’re telling.
This could be illustrated with a story about Alfred Hitchcock.
The story goes–He hated working with child actors but he
often had to. And the story goes–He was
dealing with a child actor who simply could not cry.
And, finally frustrated, Hitchcock went to the actor,
leaned over, whispered in his ear,
“Your parents have left you and they’re never coming back.”
The kid burst into tears. Hitchcock said,
“Roll ‘em” and filmed the kid.
And the kid, if you were to see him,
you’d say, “That’s–Boy, he’s–he really looks as if
he’s sad” because he was. If I had a competition where
I’d give $100,000 to the person who looks the most as if they
are in pain, it is a very good tactic to
take a pen and jam it into your groin because you will look
extremely persuasively as if you are in pain.
If I want to persuade you that I love you, would never leave
you, you can trust me with everything, it may be a superb
tactic for me to believe it. And so, this account of the
evolution of the unconscious is that certain motivations and
goals, particularly sinister ones,
are better made to be unconscious because if a person
doesn’t know they have them they will not give them away.
And this is something I think we should return to later on
when we talk about social interaction and social
relationships. One other thing on Freud–just
a story of the falsification of Freud.
I was taking my younger child home from a play date on Sunday
and he asked me out of the blue, “Why can’t you marry your
mother or your father?” Now, that’s actually a
difficult question to ask–to answer for a child,
but I tried my best to give him an answer.
And then I said–then I thought back on the Freud lecture and so
I asked him, “If you could marry anybody you want,
who would it be?” imagining he’d make explicit
the Oedipal complex and name his mother.
Instead, he paused for a moment and said, “I would marry a
donkey and a big bag of peanuts.”
[laughter] Both his parents are
psychologists and he hates these questions and at times he just
screws around with us. [laughter] Okay.
Last class I started with Freud and now I want to turn to
Skinner. And the story of Skinner and
science is somewhat different from the story of Freud.
Freud developed and championed the theory of psychoanalysis by
himself. It is as close as you could
find in science to a solitary invention.
Obviously, he drew upon all sorts of sources and
predecessors but psychoanalysis is identified as Freud’s
creation. Behaviorism is different.
Behaviorism is a school of thought that was there long
before Skinner, championed by psychologists
like John Watson, for instance.
Skinner came a bit late into this but the reason why we’ve
heard of Skinner and why Skinner is so well known is he packaged
these notions. He expanded upon them;
he publicized them; he developed them
scientifically and presented them both to the scientific
community and to the popular community and sociologically in
the 1960s and 1970s. In the United States,
behaviorism was incredibly well known and so was Skinner.
He was the sort of person you would see on talk shows.
His books were bestsellers. Now, at the core of behaviorism
are three extremely radical and interesting views.
The first is a strong emphasis on learning.
The strong view of behaviorism is everything you know,
everything you are, is the result of experience.
There’s no real human nature. Rather, people are infinitely
malleable. There’s a wonderful quote from
John Watson and in this quote John Watson is paraphrasing a
famous boast by the Jesuits. The Jesuits used to claim,
“Give me a child until the age of seven and I’ll show you the
man,” that they would take a child
and turn him into anything they wanted.
And Watson expanded on this boast,
Give me a dozen healthy infants, well-formed and my own
specified world to bring them up and I’ll guarantee to take any
one at random and train them to become any type of specialist I
might select–doctor, lawyer, artist,
merchant, chief, and yes, even beggar-man and
thief, regardless of his talents,
penchants, tendencies, abilities, vocations and race
of his ancestors. Now, you could imagine–You
could see in this a tremendous appeal to this view because
Watson has an extremely egalitarian view in a sense.
If there’s no human nature, then there’s no sense in which
one group of humans by dint of their race or their sex could be
better than another group. And Watson was explicit.
None of those facts about people will ever make any
difference. What matters to what you are is
what you learn and how you’re treated.
And so, Watson claimed he could create anybody in any way simply
by treating them in a certain fashion. A second aspect of behaviorism
was anti-mentalism. And what I mean by this is the
behaviorists were obsessed with the idea of doing science and
they felt, largely in reaction to Freud,
that claims about internal mental states like desires,
wishes, goals, emotions and so on,
are unscientific. These invisible,
vague things can never form the basis of a serious science.
And so, the behaviorist manifesto would then be to
develop a science without anything that’s unobservable and
instead use notions like stimulus and response and
reinforcement and punishment and environment that refer to real
world and tangible events. Finally, behaviorists believed
there were no interesting differences across species.
A behaviorist might admit that a human can do things that a rat
or pigeon couldn’t but a behaviorist might just say,
“Look. Those are just general
associative powers that differ” or they may even deny it.
They might say, “Humans and rats aren’t
different at all. It’s just humans tend to live
in a richer environment than rats.”
From that standpoint, from that theoretical
standpoint, comes a methodological approach which
is, if they’re all the same then
you could study human learning by studying nonhuman animals.
And that’s a lot of what they did.
Okay. I’m going to frame my
introduction–my discussion of behaviors in terms of the three
main learning principles that they argue can explain all of
human mental life, all of human behavior.
And then, I want to turn to objections to behaviorism but
these three principles are powerful and very interesting. The first is habituation.
This is the very simplest form of learning.
And what this is is technically described as a decline in the
tendency to respond to stimuli that are familiar due to
repeated exposure. “Hey!”
“Hey!” The sudden noise startles but
as it–as you hear it a second time it startles less.
The third time is just me being goofy.
It’s just–It’s–You get used to things.
And this, of course, is common enough in everyday
life. We get used to the ticking of a
clock or to noise of traffic but it’s actually a very important
form of learning because imagine life without it.
Imagine life where you never got used to anything,
where suddenly somebody steps forward and waves their hand and
you’d go, “Woah,” and then they wave
their hand again and you’d go, “Whoah,” and you
keep–[laughter] And there’s the loud ticking of
a clock and you say, “Hmmm.”
And that’s not the way animals or humans work.
You get used to things. And it’s actually critically
important to get used to things because it’s a useful adaptive
mechanism to keep track on new events and objects.
It’s important to notice something when it’s new because
then you have to decide whether it’s going to harm you,
how to deal with it, to attend to it,
but you can’t keep on noticing it.
And, in fact, you should stop noticing it
after it’s been in the environment for long enough.
So, this counts as learning because it happens through
experience. It’s a way to learn through
experience, to change your way of thinking through experience.
And also, it’s useful because harmful stimuli are noticed but
when something has shown itself to be part of the environment
you don’t notice it anymore. The existence of habituation is
important for many reasons. One thing it’s important for is
clever developmental psychologists have used
habituation as a way to study people,
creatures who can’t talk like nonhuman animals,
and young babies. And when I talk on Wednesday
about developmental psychology I’ll show different ways in
which psychologists have used habituation to study the minds
of young babies. The second sort of learning is
known as classical conditioning. And what this is in a very
general sense is the learning of an association between one
stimulus and another stimulus, where stimulus is a technical
term meaning events in the environment like a certain smell
or sound or sight. It was thought up by Pavlov.
This is Pavlov’s famous dog and it’s an example of scientific
serendipity. Pavlov, when he started this
research, had no interest at all in learning.
He was interested in saliva. And to get saliva he had to
have dogs. And he had to attach something
to dogs so that their saliva would pour out so he could study
saliva. No idea why he wanted to study
saliva, but he then discovered something.
What he would do is he’d put food powder in the dog’s mouth
to generate saliva. But Pavlov observed that when
somebody entered the room who typically gave him the food
powder, the dog–the food powder saliva
would start to come out. And later on if you–right
before or right during you give the dog some food – you ping a
bell – the bell will cause the saliva to come forth.
And, in fact, this is the apparatus that he
used for his research. He developed the theory of
classical conditioning by making a distinction between two sorts
of conditioning, two sorts of stimulus response
relationships. One is unconditioned.
An unconditioned is when an unconditioned stimulus gives
rise to an unconditioned response.
And this is what you start off with.
So, if somebody pokes you with a stick and you say,
“Ouch,” because it hurts, the poking and the “ouch” is an
unconditioned stimulus causing an unconditioned response.
You didn’t have to learn that. When Pavlov put food powder in
the dog’s mouth and saliva was generated, that’s an
unconditioned stimulus giving rise to an unconditioned
response. But what happens through
learning is that another association develops – that
between the conditioned stimulus and the conditioned response.
So when Pavlov, for instance–Well,
when Pavlov, for instance,
started before conditioning there was simply an
unconditioned stimulus, the food in the mouth,
and an unconditioned response, saliva.
The bell was nothing. The bell was a neutral stimulus.
But over and over again, if you put the bell and the
food together, pretty soon the bell will
generate saliva. And now the bell–When–You
start off with the unconditioned stimulus, unconditioned
response. When the conditioned stimulus
and the unconditioned stimulus are brought together over and
over and over again, pretty soon the conditioned
stimulus gives rise to the response.
And now it’s known as the conditioned stimulus giving rise
to the conditioned response. This is discussed in detail in
the textbook but I also–I’m going to give you–Don’t panic
if you don’t get it quite now. I’m going to give you further
and further examples. So, the idea here is,
repeated pairings of the unconditioned stimulus and the
conditioned stimulus will give rise to the response.
And there’s a difference between reinforced trials and
unreinforced trials. A reinforced trial is when the
conditioned stimulus and the unconditioned stimulus go
together. You’re–and to put it in a
crude way, you’re teaching the dog that the bell goes with the
food. An unreinforced trial is when
you get the food without the bell.
You’re not teaching the dog this.
And, in fact, once you teach an animal
something, if you stop doing the teaching the response goes away
and this is known as extinction. But here’s a graph.
If you get–They really count the number of cubic centimeters
of saliva. The dog is trained so that when
the bell comes on–Actually, I misframed it.
I’ll try again. When the bell comes connected
with food, there’s a lot of saliva.
An unreinforced response is when the bell goes on but
there’s no food. So, it’s–Imagine you’re the
dog. So, you get food in your mouth,
“bell, food, bell, food,” and now “bell.”
But next you get “bell, bell, bell.”
You give it up. You stop.
You stop responding to the bell. A weird thing which is
discussed in the textbook is if you wait a while and then you
try it again with the bell after a couple of hours,
the saliva comes back. This is known as spontaneous
recovery. So, this all seems a very
technical phenomena related to animals and the like but it’s
easy to see how it generalizes and how it extends.
One interesting notion is that of stimulus generalization.
And stimulus generalization is the topic of one of your
articles in The Norton Reader,
the one by Watson, John Watson,
the famous behaviorist, who reported a bizarre
experiment with a baby known as Little Albert.
And here’s the idea. Little Albert originally liked
rats. In fact, I’m going to show you
a movie of Little Albert originally liking rats. See.
He’s okay. No problem.
Now, Watson did something interesting.
As Little Albert was playing with the rat,
“Oh, I like rats, oh,” Watson went behind the
baby–this is the–it’s in the chapter–and banged the metal
bar right here . The baby, “Aah,” screamed,
started to sob. Okay.
What’s the unconditioned stimulus?
Somebody. The loud noise,
the bar, the bang. What’s the unconditioned
response? Crying, sadness, misery.
And as a result of this, Little Albert grew afraid of
the rat. So there–what would be the
conditioned stimulus? The rat.
What would be the conditioned response?
Moreover, this fear extended to other things.
So, this is a very weird and unpersuasive clip.
But the idea is–the clip is to make the point that the fear
will extend to a rabbit, a white rabbit.
So, the first part, Little Albert’s fine with the
white rabbit. The second part is after he’s
been conditioned and he’s kind of freaked out with the white
rabbit. The problem is in the second
part they’re throwing the rabbit at him but now he’s okay. [laughter] Is the mic on?
Oh. This is fine.
This is one of a long list of experiments that we can’t do
anymore. So, classical conditioning is
more than a laboratory phenomena.
The findings of classical conditioning have been extended
and replicated in all sorts of animals including crabs,
fish, cockroaches and so on. And it’s been argued to be an
extension of–it’s argued to underlie certain interesting
aspects of human responses. So, I have some examples here.
One example is fear. So, the Little Albert idea–The
Little Albert experiment, provides an illustration for
how phobias could emerge. Some proportion of people in
this room have phobias. Imagine you’re afraid of dogs.
Well, a possible story for the–for why you became afraid
of dogs is that one day a dog came up and he was a neutral
stimulus. No problem.
And all of a sudden he bit you. Now the pain of a bite,
being bit, and then the pain and fear of that is an
unconditioned stimulus, unconditioned response.
You’re just born with that, “ow.”
But the presence of the dog there is a conditioned stimulus
and so you grew to be afraid of dogs.
If you believe this, this also forms the basis for
ways for a theory of how you could make phobias go away.
How do you make conditioned stimulus, conditioned response
things go away? Well, what you do is you
extinguish them. How do you extinguish them?
Well, you show the thing that would cause you to have the fear
without the unconditioned stimulus.
Here’s an illustration. It’s a joke.
Sorry. He’s simultaneously confronting
the fear of heights, snakes, and the dark because
he’s trapped in that thing and the logic is–the logic of–the
logic is not bad. He’s stuck in there.
Those are all the–his conditioned stimulus.
But nothing bad happens so his fear goes away.
The problem with this is while he’s stuck in there he has this
screaming, horrific panic attack and then it makes his fear much
worse. So, what they do now though,
and we’ll talk about this much later in the course when we talk
about clinical psychology–but one cure for phobias does draw
upon, in a more intelligent way,
the behaviorist literature. So, the claim about a phobia is
that there’s a bad association between, say dog and fear,
or between airplanes or snakes and some bad response.
So, what they do is what’s called, “systematic
desensitization,” which is they expose you to what causes you
the fear but they relax you at the same time so you replace the
aversive classical conditioned fear with something more
they used to teach people relaxation exercises but that
proves too difficult. So nowadays they just pump you
full of some drug to get you really happy and so you’re
really stoned out of your head, you’re and this isn’t so bad.
It’s more complicated than that but the notion is you can use
these associative tools perhaps to deal with questions about
fear, phobias and how they go away.
Hunger. We’ll spend some time in this
course discussing why we eat and when we eat.
And one answer to why we eat and when we eat is that there’s
cues in the environment that are associated with eating.
And these cues generate hunger. For those of you who are trying
to quit smoking, you’ll notice that there’s
time–or to quit drinking there’s times of the day or
certain activities that really make you want to smoke or really
make you want to drink. And from a behaviorist point of
view this is because of the associative history of these
things. More speculatively,
classical conditioning has been argued to be implicated in the
formation of sexual desire, including fetishes.
So a behaviorist story about fetishes, for instance,
is it’s straightforward classical conditioning.
Just as your lover’s caress brings you to orgasm,
your eyes happen to fall upon a shoe.
Through the simple tools of classical conditioning then,
the shoe becomes a conditioned stimulus giving rise to the
conditioned response of sexual pleasure.
This almost certainly is not the right story but again,
just as in phobias, some ideas of classical
conditioning may play some role in determining what we like and
what we don’t like sexually. And in fact,
one treatment for pedophiles and rapists involved controlled
fantasies during masturbation to shift the association from
domination and violence, for instance,
to develop more positive associations with sexual
pleasure. So the strong classical
conditioning stories about fetishes and fears sound silly
and extreme and they probably are but at the same time
classical conditioning can be used at least to shape the focus
of our desires and of our interests.
Final thought actually is–Oh, yeah.
Okay. So, what do we think about
classical conditioning? We talked about what
habituation is for. What’s classical conditioning
for? Well, the traditional view is
it’s not for anything. It’s just association.
So, what happens is the UCS and the CS, the bell and the food,
go together because they happen at the same time.
And so classical conditioning should be the strongest when
these two are simultaneous and the response to one is the same
as the response to the other. This is actually no longer the
mainstream view. The mainstream view is now a
little bit more interesting. It’s that what happens in
classical conditioning is preparation.
What happens is you become sensitive to a cue that an event
is about to happen and that allows you to prepare for the
event. This makes certain predictions.
It predicts that the best timing is when the conditioned
stimulus, which is the signal, comes before the unconditioned
stimulus, which is what you have to prepare for.
And it says the conditioned response may be different from
the unconditioned response. So, move away from food.
Imagine a child who’s being beaten by his father.
And when his father raises his hand he flinches.
Well, that’s classical conditioning.
What happened in that case is he has learned that the raising
of a hand is a signal that he is about to be hit and so he
responds to that signal. His flinch is not the same
response that one would give if one’s hit.
If you’re hit, you don’t flinch. If you’re hit,
you might feel pain or bounce back or something.
Flinching is preparation for being hit.
And, in general, the idea of what goes on in
classical conditioning is that the response is sort of a
preparation. The conditioned response is a
preparation for the unconditioned stimulus.
Classical conditioning shows up all over the place.
As a final exercise, and I had to think about
it–Has anybody here seen the movie “Clockwork Orange”?
A lot of you. It’s kind of a shocking movie
and unpleasant and very violent but at its core one of the main
themes is right out of Intro Psych.
It’s classical conditioning. And a main character,
who is a violent murderer and rapist, is brought in by some
psychologists for some therapy. And the therapy he gets is
classical conditioning. In particular,
what happens is he is given a drug that makes him violently
ill, extremely nauseous. And then his eyes are propped
open and he’s shown scenes of violence.
As a result of this sort of conditioning,
he then – when he experiences real world violence – he
responds with nausea and shock; basically, training him to get
away from these acts of violence.
In this example–Take a moment. Don’t say it aloud.
Just take a moment. What’s the unconditioned
Anybody, what’s the unconditioned stimulus?
Somebody just say it. The drug.
What’s the unconditioned response?
Nausea. What’s the conditioned stimulus?
Violence. What’s the conditioned response?
Perfect. The third and final type of
learning is known as operant conditioning or instrumental
conditioning. And this is the thing,
this is the theory championed and developed most extensively
by Skinner. What this is is learning the
relationships between what you do and how successful or
unsuccessful they are, learning what works and what
doesn’t. It’s important.
This is very different from classical conditioning and one
way to see how this is different is for classical conditioning
you don’t do anything. You could literally be strapped
down and be immobile and these connections are what you
appreciate and you make connections in your mind.
Instrumental conditioning is voluntary.
You choose to do things and by dint of your choices.
Some choices become more learned than others.
So, the idea itself was developed in the nicest form by
Thorndike who explored how animals learn.
Remember behaviorists were entirely comfortable studying
animals and drawing extrapolations to other animals
and to humans. So, he would put a cat in a
puzzle box. And the trick to a puzzle box
is there’s a simple way to get out but you have to kind of pull
on something, some special lever,
to make it pop open. And Thorndike noted that cats
do not solve this problem through insight.
They don’t sit in the box for a while and mull it over and then
figure out how to do it. Instead, what they do is they
bounce all around doing different things and gradually
get better and better at it. So, what they do is,
the first time they might scratch at the bars,
push at the ceiling, dig at the floor,
howl, etc., etc. And one of their behaviors is
pressing the lever. The lever gets them out of the
box, but after more and more trials they stopped scratching
at the bars, pushing at the ceiling and so on.
They just pressed the lever. And if you graph it,
they gradually get better and better.
They throw out all of these behaviors randomly.
Some of them get reinforced and those are the ones that survive
and others don’t get reinforced and those are the ones that go
extinct. And it might occur to some of
you that this seems to be an analogy with the Darwinian
theory of natural selection where there’s a random
assortment of random mutations. And sexual selections give rise
to a host of organisms, some of which survive and are
fit and others which aren’t. And in fact,
Skinner explicitly made the analogy from the natural
selection of species to the natural selection of behavior.
So this could be summarized as the law of effect,
which is a tendency to perform – an action’s increased if
rewarded, weakened if it’s not. And Skinner extended this more
generally. So, to illustrate Skinnerian
theory in operant conditioning I’ll give an example of training
a pig. So here is the idea.
You need to train a pig and you need to do so through operant
conditioning. So one of the things you want
to do is–The pig is going to do some things you like and some
things you don’t like. And so what you want to do,
basically drawing upon the law of effect, is reinforce the pig
for doing good things. Suppose you want the pig to
walk forward. So, you reinforce the pig for
walking forward and you punish the pig for walking backward.
And if you do that over the fullness of time,
your reinforcement and punishment will give rise to a
pig who walks forward. There’s two–One technical
distinction that people love to put on Intro Psych exams is that
the difference between positive reinforcement and negative
reinforcement. Reinforcement is something that
makes the behavior increase. Negative reinforcement is very
different from punishment. Negative reinforcement is just
a type of reward. The difference is in positive
reinforcement you do something; in negative reinforcement you
take away something aversive. So, imagine the pig has a heavy
collar and to reward the pig for walking forward you might remove
the heavy collar. So, these are the basic
techniques to train an animal. But it’s kind of silly because
suppose you want your pig to dance.
You don’t just want your pig to walk forward.
You want your pig to dance. Well, you can’t adopt the
policy of “I’m going to wait for this pig to dance and when it
does I’m going to reinforce it” because it’s going to take you a
very long time. Similarly, if you’re dealing
with immature humans and you want your child to get you a
beer, you can’t just sit,
wait for the kid to give you a beer and uncap the bottle and
You’ve got to work your way to it.
And the act of working your way to it is known as shaping.
So, here is how to get a pig to dance.
You wait for the pig to do something that’s halfway close
to dancing, like stumbling, and you reward it.
Then it does something else that’s even closer to dancing
and you reward it. And you keep rewarding it as it
gets closer to closer. Here’s how to get your child to
bring you some beer. You say, “Johnny,
could you go to the kitchen and get me some beer?”
And he walks to the kitchen and then he forgets why he’s there
and you run out there. “You’re such a good kid.
And then you get him to–and then finally you get him to also
open up the refrigerator and get the beer,
open the door, get the–and in that way you
can train creatures to do complicated things.
Skinner had many examples of this.
Skinner developed, in World War II,
a pigeon guided missile. It was never actually used but
it was a great idea. And people, in fact–The
history of the military in the United States and other
countries includes a lot of attempts to get animals like
pigeons or dolphins to do interesting and deadly things
through various training. More recreational,
Skinner was fond of teaching animals to play Ping-Pong.
And again, you don’t teach an animal to play Ping-Pong by
waiting for it to play Ping-Pong and then rewarding it.
Rather, you reward approximations to it.
And basically, there are primary reinforcers.
There are some things pigs naturally like,
food for instance. There are some things pigs
actually automatically don’t like, like being hit or shocked.
But in the real world when dealing with humans,
but even when dealing with animals,
we don’t actually always use primary reinforcers or negative
reinforcers. What we often use are things
like–for my dog saying, “Good dog.”
Now, saying “Good dog” is not something your dog has been
built, pre-wired, to find pleasurable.
But what happens is you can do a two-step process.
You can make “Good dog” positive through classical
conditioning. You give the dog a treat and
say, “Good dog.” Now the phrase “good dog” will
carry the rewarding quality. And you could use that
rewarding quality in order to train it.
And through this way behaviorists have developed
token economies where they get nonhuman animals to do
interesting things for seemingly arbitrary rewards like poker
chips. And in this way you can
increase the utility and ease of training.
Finally, in the examples we’re giving, whenever the pig does
something you like you reinforce it.
But that’s not how real life works.
Real life for both humans and animals involved cases where the
reinforcement doesn’t happen all the time but actually happens
according to different schedules.
And so, there is the distinction between fixed
schedules versus ratios – variable schedules and ratio
versus interval. And this is something you could
print out to look at. I don’t need to go over it in
detail. The difference between ratio is
a reward every certain number of times somebody does something.
So, if every tenth time your dog brought you the newspaper
you gave it hugs and treats; that’s ratio.
An interval is over a period of time.
So, if your dog gives you–if your dog, I don’t know,
dances for an hour straight, that would be an interval
thing. And fixed versus variable
speaks to whether you give a reward on a fixed schedule,
every fifth time, or variable,
sometimes on the third time, sometimes on the seventh time,
and so on. And these are–There are
examples here and there’s no need to go over them.
It’s easy enough to think of examples in real life.
So, for example, a slot machine is variable
ratio. It goes off after it’s been hit
a certain number of times. It doesn’t matter how long it
takes you for–to do it. It’s the number of times you
pull it down. But it’s variable because it
doesn’t always go off on the thousandth time.
You don’t know. It’s unpredictable.
The slot machine is a good example of a phenomena known as
the partial reinforcement effect.
And this is kind of neat. It makes sense when you hear it
but it’s the sort of finding that’s been validated over and
over again with animals and nonhumans.
Here’s the idea. Suppose you want to train
somebody to do something and you want the training such that
they’ll keep on doing it even if you’re not training them
anymore, which is typically what you
want. If you want that,
the trick is don’t reinforce it all the time.
Behaviors last longer if they’re reinforced
intermittently and this is known as “the partial reinforcement
effect.” Thinking of this
psychologically, it’s as if whenever you put
something in a slot machine it gave you money,
then all of a sudden it stopped.
You keep on doing it a few times but then you say,
“Fine. It doesn’t work,” but what if
it gave you money one out of every hundred times?
Now you keep on trying and because the reinforcement is
intermittent you don’t expect it as much and so your behavior
will persist across often a huge amount of time.
Here’s a good example. What’s the very worst thing to
do when your kid cries to go into bed with you and you don’t
want him to go into bed with you?
Well, one–The worst thing to do is for any–Actually,
for any form of discipline with a kid is to say,
“No, absolutely not. No, no, no, no.”
“Okay.” And then later on the kid’s
going to say, “I want to do it again” and you
say no and the kid keeps asking because you’ve put it,
well, put it as in a psychological way,
not the way the behaviorists would put it.
The kid knows okay, he’s not going to get it right
away, he’s going to keep on asking.
And so typically, what you’re doing inadvertently
in those situations is you’re exploiting the partial
reinforcement effect. If I want my kid to do
something, I should say yes one out of every ten times.
Unfortunately, that’s the evolution of
nagging. Because you nag,
you nag, you nag, the person says,
“Fine, okay,” and that reinforces it.
If Skinner kept the focus on rats and pigeons and dogs,
he would not have the impact that he did but he argued that
you could extend all of these notions to humans and to human
behavior. So for an example,
he argued that the prison system needs to be reformed
because instead of focusing on notions of justice and
retribution what we should do is focus instead on questions of
reinforcing good behaviors and punishing bad ones.
He argued for the notions of operant conditioning to be
extended to everyday life and argued that people’s lives would
become fuller and more satisfying if they were
controlled in a properly behaviorist way.
Any questions about behaviorism? What are your questions about
behaviorism? [laughter] Yes.
Student: [inaudible]–wouldn’t there be
extinction after a while? [inaudible]
Professor Paul Bloom: Good question.
The discussion was over using things like poker chips for
reinforcement and the point is exactly right.
Since the connection with the poker chips is established
through classical conditioning, sooner or later by that logic
the poker chips would lose their power to serve as reinforcers.
You’d have to sort of start it up again, retrain again.
If you have a dog and you say “Good dog” to reward the dog,
by your logic, which is right,
at some point you might as well give the dog a treat along with
the “Good dog.” Otherwise, “Good dog” is not
going to cut it anymore. Yes.
Professor Paul Bloom: As far as I know,
Skinner and Skinnerian psychologists were never
directly involved in the creation of prisons.
On the other hand, the psychological theory of
behaviorism has had a huge impact and I think a lot of
people’s ways of thinking about criminal justice and criminal
law has been shaped by behaviorist principles.
So for instance, institutions like mental
institutions and some prisons have installed token economies
where there’s rewards for good behavior,
often poker chips of a sort. And then you could cash them in
for other things. And, to some extent,
these have been shaped by an adherence to behaviorist
So, here are the three general positions of behaviorism.
(1) That there is no innate knowledge.
All you need is learning. (2) That you could explain
human psychology without mental notions like desires and goals.
(3) And that these mechanisms apply across all domains and
across all species. I think it’s fair to say that
right now just about everybody agrees all of these three claims
are mistaken. First, we know that it’s not
true that everything is learned. There is considerable evidence
for different forms of innate knowledge and innate desires and
we’ll look–and we’ll talk about it in detail when we look at
case studies like language learning,
the development of sexual preference, the developing
understanding of material objects.
There’s a lot of debate over how much is innate and what the
character of the built-in mental systems are but there’s nobody
who doubts nowadays that a considerable amount for humans
and other animals is built-in. Is it true that talking about
mental states is unscientific? Nobody believes this anymore
either. Science, particularly more
advanced sciences like physics or chemistry,
are all about unobservables. They’re all about things you
can’t see. And it makes sense to explain
complex and intelligent behavior in terms of internal mechanisms
and internal representations. Once again, the computer
revolution has served as an illustrative case study.
If you have a computer that plays chess and you want to
explain how the computer plays chess,
it’s impossible to do so without talking about the
programs and mechanisms inside the computer.
Is it true that animals need reinforcement and punishment to
learn? No, and there’s several
demonstrations at the time of Skinner suggesting that they
don’t. This is from a classic study by
Tolman where rats were taught to run a maze.
And what they found was the rats did fine.
They learn to run a maze faster and faster when they’re
regularly rewarded but they also learn to run a maze faster and
faster if they are not rewarded at all.
So the reward helps, but the reward is in no sense
necessary. And here’s a more sophisticated
illustration of the same point. Professor Paul Bloom:
And this is the sort of finding, an old finding from
before most of you were born, that was a huge embarrassment
for the Skinnerian theory, as it suggests that rats in
fact had mental maps, an internal mechanism that they
used to understand the world – entirely contrary to the
behaviorist idea everything could be explained in terms of
reinforcement and punishment. Finally, is it true that
there’s no animal-specific constraints for learning?
And again, the answer seems to be “no.”
Animals, for instance, have natural responses.
So, you could train a pigeon to peck for food but that’s because
pecking for food is a very natural response.
It’s very difficult to train it to peck to escape a situation.
You can train it to flap its wings to escape a situation but
it’s very difficult to get it to flap its wings for food.
And the idea is they have sort of natural responses that these
learning situations might exploit and might channel,
but essentially, they do have certain natural
ways of acting towards the world.
We know that not all stimuli and responses are created equal.
So, the Gray textbook has a very nice discussion of the
Garcia effect. And the Garcia effect goes like
this. Does anybody here have any food
aversions? I don’t mean foods you don’t
like. I mean foods that really make
you sick. Often food aversions in humans
and other animals can be formed through a form of association.
What happens is suppose you have the flu and you get very
nauseous and then at the same point you eat some sashimi for
the first time. The connection between being
nauseous and eating a new food is very potent.
And even if you know intellectually full well that
the sashimi isn’t why you became nauseous, still you’ll develop
an aversion to this new food. When I was younger – when I
was a teenager – I drank this Greek liqueur,
ouzo, with beer. I didn’t have the flu at the
time but I became violently ill. And as a result I cannot abide
the smell of that Greek liqueur. Now, thank God it didn’t
develop into an aversion to beer but– [laughter]
Small miracles. But the smell is very
distinctive and for me–was new to me.
And so, through the Garcia effect I developed a strong
aversion. What’s interesting though is
the aversion is special so if you take an animal and you give
it a new food and then you give it a drug to make it nauseous it
will avoid that food. But if you take an animal and
you give it a new food and then you shock it very painfully it
won’t avoid the new food. And the idea is that a
connection between what something tastes and getting
sick is natural. We are hard wired to say, “Look.
If I’m going to eat a new food and I’m going to get nauseous,
I’m going to avoid that food.” The Garcia effect is that this
is special to taste and nausea. It doesn’t extend more
generally. Finally, I talked about phobias
and I’ll return to phobias later on in this course.
But the claim that people have formed their phobias through
classical conditioning is almost always wrong.
Instead, it turns out that there are certain phobias that
we’re specially evolved to have. So, both humans and
chimpanzees, for instance, are particularly prone to
develop fears of snakes. And when we talk about the
emotions later on in the course we’ll talk about this in more
detail. But what seems likely is the
sort of phobias you’re likely to have does not have much to do
with your personal history but rather it has a lot to do with
your evolutionary history. Finally, the other reading
you’re going to do for this part–section of the course is
Chomsky’s classic article, his “Review of Verbal
Behavior.” Chomsky is one of the most
prominent intellectuals alive. He’s still a professor at MIT,
still publishes on language and thought, among other matters.
And the excerpt you’re going to read is from his “Review of
Verbal Behavior.” And this is one of the most
influential intellectual documents ever written in
psychology because it took the entire discipline of behaviorism
and, more than everything else,
more than any other event, could be said to have destroyed
it or ended it as a dominant intellectual endeavor.
And Chomsky’s argument is complicated and interesting,
but the main sort of argument he had to make is–goes like
this. When it comes to humans,
the notions of reward and punishment and so on that
Skinner tried to extend to humans are so vague it’s not
science anymore. And remember the discussion we
had with regard to Freud. What Skinner–What Chomsky is
raising here is the concern of unfalsifiablity.
So, here’s the sort of example he would discuss.
Skinner, in his book Verbal Behavior,
talks about the question of why do we do things like talk to
ourselves, imitate sounds,
create art, give bad news to an enemy, fantasize about pleasant
situations? And Skinner says that they all
involve reinforcement; those are all reinforced
behaviors. But Skinner doesn’t literally
mean that when we talk to ourselves somebody gives us food
pellets. He doesn’t literally mean even
that when we talk to ourselves somebody pats us on the head and
says, “Good man. Perfect.
I’m very proud.” What he means,
for instance, in this case is well,
talking to yourself is self-reinforcing or giving bad
news to an enemy is reinforcing because it makes your enemy feel
bad. Well, Chomsky says the problem
is not that that’s wrong. That’s all true.
It’s just so vague as to be useless.
Skinner isn’t saying anything more.
To say giving bad news to an enemy is reinforcing because it
makes the enemy feel bad doesn’t say anything different from
giving bad news to an enemy feels good because we like to
give bad news to an enemy. It’s just putting it in more
scientific terms. More generally,
Chomsky suggests that the law of effect when applied to humans
is either trivially true, trivially or uninterestingly
true, or scientifically robust and obviously false.
So, if you want to expand the notion of reward or
reinforcement to anything, then it’s true.
So why did you come–those of you who are not freshmen–Oh,
you–Why did you come? All of you, why did you come to
Yale for a second semester? “Well, I repeated my action
because the first semester was rewarding.”
Okay. What do you mean by that?
Well, you don’t literally mean that somebody rewarded you,
gave you pellets and stuff. What you mean is you chose to
come there for the second semester.
And there’s nothing wrong with saying that but we shouldn’t
confuse it with science. And more generally,
the problem is you can talk about what other people do in
terms of reinforcement and punishment and operant
conditioning and classical conditioning.
But in order to do so, you have to use terms like
“punishment” and “reward” and “reinforcement” in such a vague
way that in the end you’re not saying anything scientific.
So, behaviorism as a dominant intellectual field has faded,
but it still leaves behind an important legacy and it still
stands as one of the major contributions of twentieth
century psychology. For one thing,
it has given us a richer understanding of certain
learning mechanisms, particularly with regard to
nonhumans. Mechanisms like habituation,
classical conditioning and operant conditioning are real;
they can be scientifically studied;
and they play an important role in the lives of animals and
probably an important role in human lives as well.
They just don’t explain everything.
Finally, and this is something I’m going to return to on
Wednesday actually, behaviorists have provided
powerful techniques for training particularly for nonverbal
creatures so this extends to animal trainers.
But it also extends to people who want to teach young children
and babies and also want to help populations like the severely
autistic or the severely retarded.
Many of these behaviorist techniques have proven to be
quite useful. And in that regard,
as well as in other regards, it stands as an important