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  • 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 fishto 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, "Rollem" 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 foodyou ping a bellthe 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 developsthat 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? Fear.

  • Excellent. 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 positive.

  • Traditionally, 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 thenwhen he experiences

  • real world violencehe 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 stimulus?

  • Okay. 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 say,

  • "Excellent. Good.

  • Hugs." 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. Congratulations.

  • Hugs." 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. Student:

  • [inaudible] 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 principles.

  • Okay. 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 youngerwhen 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 contribution.

Professor Paul Bloom: I actually want to begin by

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