04 Foundations: Skinner 心理学基础:斯金纳
作者: 耶鲁大学 / 9768次阅读 时间: 2010年12月01日
标签: 视频 斯金纳 心理学导论

+~p B$V@4l+^ c0Professor Paul Bloom: I actually want to begin by going backto Freud and hitting a couple of loose ends. There was a point in mylecture on Wednesday where I skipped over some parts. I said, "We don'thave time for this" and I just whipped past it. And I couldn't sleepover the weekend. I've been tormented. I shouldn't have skipped thatand I want to hit--Let me tell you why I skipped it. The discussion Iskipped was the discussion of why we would have an unconscious at all.So, I was talking about the scientifically respectable ideas of Freudand I want to talk about some new ideas about why there could be anunconscious.心理学空间n:}8cu0G

nqm'}4n$S0Now, the reason why I skipped it is I'm not sure this is the bestway to look at the question. As we will learn throughout the course, byfar the vast majority of what our brains do, the vast majority of whatour minds do, is unconscious and we're unaware of it. So the rightquestion to ask may not be, "Why are some things unconscious?" butrather, why is this tiny subset of mental life--why is this conscious?On the other hand, these claims about the utility of unconsciousness, Ithink, are provocative and interesting. So I just wanted to quicklyshare them with you.


So, the question is, from an evolutionary standpoint, "Why would anunconscious evolve?" And an answer that some psychologists andbiologists have given is deception. So, most animals do some deception.And deception defined broadly is simply to act or be in some way thatfools others into believing or thinking or responding to somethingthat's false.

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3Cw+m+N dKJ%x_0There's physical examples of deception. When threatened,chimpanzees--their hair stands up on end and that makes them lookbigger 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 rodsticking 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 tothemselves be devoured. But humans, primates in general butparticularly humans, are masters of deception. We use our minds and ourbehaviors and our actions continually to try to trick people intobelieving what's not true. We try to trick people, for instance, intobelieving that we're tougher, smarter, sexier, more reliable, moretrustworthy and so on, than we really are. And a large part of socialpsychology concerns the way in which we present ourselves to otherpeople so as to make the maximally positive impression even when thatimpression isn't true.心理学空间 @5x?f(M |

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At the same time, though, we've also evolved very good lie detectionmechanisms. So not only is there evolutionary pressure for me to lie toyou, for me to persuade you for instance, that if we're going to havea--if you are threatening me don't threaten me, I am not the sort ofman you could screw around with. But there's evolutionary pressure foryou to look and say, "No. You are the sort of man you could screwaround with. I can tell." So how do you become a good liar? And here'swhere the unconscious comes in. The hypothesis is: the best lies arelies we tell ourselves. You're a better liar, more generally, if youbelieve the lie that you're telling.心理学空间"j!_3n1s@)K!{L


This could be illustrated with a story about Alfred Hitchcock. Thestory goes--He hated working with child actors but he often had to. Andthe story goes--He was dealing with a child actor who simply could notcry. And, finally frustrated, Hitchcock went to the actor, leaned over,whispered in his ear, "Your parents have left you and they're nevercoming back." The kid burst into tears. Hitchcock said, "Roll ‘em" andfilmed 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. IfI had a competition where I'd give $100,000 to the person who looks themost as if they are in pain, it is a very good tactic to take a pen andjam it into your groin because you will look extremely persuasively asif you are in pain. If I want to persuade you that I love you, wouldnever leave you, you can trust me with everything, it may be a superbtactic for me to believe it. And so, this account of the evolution ofthe unconscious is that certain motivations and goals, particularlysinister ones, are better made to be unconscious because if a persondoesn't know they have them they will not give them away. And this issomething I think we should return to later on when we talk aboutsocial interaction and social relationships.心理学空间$mlGE9Y7d"z9^

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One other thing on Freud--just a story of the falsification ofFreud. I was taking my younger child home from a play date on Sundayand he asked me out of the blue, "Why can't you marry your mother oryour father?" Now, that's actually a difficult question to ask--toanswer for a child, but I tried my best to give him an answer. And thenI 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'dmake explicit the Oedipal complex and name his mother. Instead, hepaused for a moment and said, "I would marry a donkey and a big bag ofpeanuts." [laughter] Both his parents are psychologists and he hatesthese questions and at times he just screws around with us.[laughter]

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"dM'I a&@PN0Okay. Last class I started with Freud and now I want to turn toSkinner. And the story of Skinner and science is somewhat differentfrom the story of Freud. Freud developed and championed the theory ofpsychoanalysis by himself. It is as close as you could find in scienceto a solitary invention. Obviously, he drew upon all sorts of sourcesand predecessors but psychoanalysis is identified as Freud's creation.Behaviorism is different. Behaviorism is a school of thought that wasthere long before Skinner, championed by psychologists like JohnWatson, for instance. Skinner came a bit late into this but the reasonwhy we've heard of Skinner and why Skinner is so well known is hepackaged these notions. He expanded upon them; he publicized them; hedeveloped them scientifically and presented them both to the scientificcommunity and to the popular community and sociologically in the 1960sand 1970s. In the United States, behaviorism was incredibly well knownand so was Skinner. He was the sort of person you would see on talkshows. His books were bestsellers.心理学空间G/lZ"aO4|0_w

Aa4Z7_(i/C7F5Y-|0Now, at the core of behaviorism are three extremely radical andinteresting views. The first is a strong emphasis on learning. Thestrong 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 JohnWatson and in this quote John Watson is paraphrasing a famous boast bythe Jesuits. The Jesuits used to claim, "Give me a child until the ageof seven and I'll show you the man," that they would take a child andturn him into anything they wanted. And Watson expanded on thisboast,

Give me a dozen healthy infants, well-formed and my ownspecified world to bring them up and I'll guarantee to take any one atrandom and train them to become any type of specialist I mightselect--doctor, lawyer, artist, merchant, chief, and yes, evenbeggar-man and thief, regardless of his talents, penchants, tendencies,abilities, vocations and race of his ancestors.
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Now, you could imagine--You could see in this a tremendous appeal tothis 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 ofhumans by dint of their race or their sex could be better than anothergroup. And Watson was explicit. None of those facts about people willever make any difference. What matters to what you are is what youlearn and how you're treated. And so, Watson claimed he could createanybody in any way simply by treating them in a certain fashion.心理学空间)om7YVuvv

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A second aspect of behaviorism was anti-mentalism. And what I meanby this is the behaviorists were obsessed with the idea of doingscience and they felt, largely in reaction to Freud, that claims aboutinternal mental states like desires, wishes, goals, emotions and so on,are unscientific. These invisible, vague things can never form thebasis of a serious science. And so, the behaviorist manifesto wouldthen be to develop a science without anything that's unobservable andinstead use notions like stimulus and response and reinforcement andpunishment and environment that refer to real world and tangibleevents.心理学空间 wB;[ r2QA U6M/h2E}

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Finally, behaviorists believed there were no interesting differencesacross species. A behaviorist might admit that a human can do thingsthat a rat or pigeon couldn't but a behaviorist might just say, "Look.Those are just general associative powers that differ" or they may evendeny it. They might say, "Humans and rats aren't different at all. It'sjust humans tend to live in a richer environment than rats." From thatstandpoint, from that theoretical standpoint, comes a methodologicalapproach which is, if they're all the same then you could study humanlearning by studying nonhuman animals. And that's a lot of what theydid.

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](Q S zb6k G0Okay. I'm going to frame my introduction--my discussion of behaviorsin terms of the three main learning principles that they argue canexplain all of human mental life, all of human behavior. And then, Iwant to turn to objections to behaviorism but these three principlesare powerful and very interesting.

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Og.UBL/E0The first is habituation. This is the very simplest form oflearning. And what this is is technically described as a decline in thetendency to respond to stimuli that are familiar due to repeatedexposure. "Hey!" [shouting, then pausing] "Hey!" [shouting again] Thesudden noise startles but as it--as you hear it a second time itstartles less. The third time is just me being goofy. It'sjust--It's--You get used to things. And this, of course, is commonenough in everyday life. We get used to the ticking of a clock or tonoise of traffic but it's actually a very important form of learningbecause imagine life without it. Imagine life where you never got usedto anything, where suddenly somebody steps forward and waves their handand you'd go, "Woah," [as if surprised] and then they wave their handagain and you'd go, "Whoah," [as if surprised again] and youkeep--[laughter]心理学空间*Y(sY6G To M#s(I

:V,Dv Oek0And there's the loud ticking of a clock and you say, "Hmmm." [actingas if he's interested in the sound of a clock ticking] And that's notthe way animals or humans work. You get used to things. And it'sactually critically important to get used to things because it's auseful adaptive mechanism to keep track on new events and objects. It'simportant to notice something when it's new because then you have todecide whether it's going to harm you, how to deal with it, to attendto it, but you can't keep on noticing it. And, in fact, you should stopnoticing it after it's been in the environment for long enough. So,this counts as learning because it happens through experience. It's away to learn through experience, to change your way of thinking throughexperience. And also, it's useful because harmful stimuli are noticedbut when something has shown itself to be part of the environment youdon't notice it anymore.

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The existence of habituation is important for many reasons. Onething it's important for is clever developmental psychologists haveused habituation as a way to study people, creatures who can't talklike nonhuman animals, and young babies. And when I talk on Wednesdayabout developmental psychology I'll show different ways in whichpsychologists have used habituation to study the minds of youngbabies.


2F1r%W[)G+|S6\']i/N:v0The second sort of learning is known as classical conditioning. Andwhat this is in a very general sense is the learning of an associationbetween one stimulus and another stimulus, where stimulus is atechnical term meaning events in the environment like a certain smellor sound or sight. It was thought up by Pavlov. This is Pavlov's famousdog and it's an example of scientific serendipity. Pavlov, when hestarted this research, had no interest at all in learning. He wasinterested in saliva. And to get saliva he had to have dogs. And he hadto attach something to dogs so that their saliva would pour out so hecould study saliva. No idea why he wanted to study saliva, but he thendiscovered something. What he would do is he'd put food powder in thedog's mouth to generate saliva. But Pavlov observed that when somebodyentered the room who typically gave him the food powder, the dog--thefood powder saliva would start to come out. And later on if you--rightbefore 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 theapparatus that he used for his research.心理学空间1q0{ Z+lSJ

yZk4fP5V%t`0He developed the theory of classical conditioning by making adistinction between two sorts of conditioning, two sorts of stimulusresponse relationships. One is unconditioned. An unconditioned is whenan unconditioned stimulus gives rise to an unconditioned response. Andthis is what you start off with. So, if somebody pokes you with a stickand you say, "Ouch," because it hurts, the poking and the "ouch" is anunconditioned stimulus causing an unconditioned response. You didn'thave to learn that.

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When Pavlov put food powder in the dog's mouth and saliva wasgenerated, that's an unconditioned stimulus giving rise to anunconditioned response. But what happens through learning is thatanother association develops – that between the conditioned stimulusand the conditioned response. So when Pavlov, for instance--Well, whenPavlov, for instance, started before conditioning there was simply anunconditioned stimulus, the food in the mouth, and an unconditionedresponse, saliva. The bell was nothing. The bell was a neutralstimulus. But over and over again, if you put the bell and the foodtogether, pretty soon the bell will generate saliva. And now thebell--When--You start off with the unconditioned stimulus,unconditioned response. When the conditioned stimulus and theunconditioned stimulus are brought together over and over and overagain, pretty soon the conditioned stimulus gives rise to the response.And now it's known as the conditioned stimulus giving rise to theconditioned response. This is discussed in detail in the textbook but Ialso--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.

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So, the idea here is, repeated pairings of the unconditionedstimulus and the conditioned stimulus will give rise to the response.And there's a difference between reinforced trials and unreinforcedtrials. A reinforced trial is when the conditioned stimulus and theunconditioned stimulus go together. You're--and to put it in a crudeway, you're teaching the dog that the bell goes with the food. Anunreinforced trial is when you get the food without the bell. You'renot teaching the dog this. And, in fact, once you teach an animalsomething, if you stop doing the teaching the response goes away andthis is known as extinction.心理学空间,K4lH-n(Cdqa"]%o L


But here's a graph. If you get--They really count the number ofcubic centimeters of saliva. The dog is trained so that when the bellcomes on--Actually, I misframed it. I'll try again. When the bell comesconnected with food, there's a lot of saliva. An unreinforced responseis when the bell goes on but there's no food. So, it's--Imagine you'rethe dog. So, you get food in your mouth, "bell, food, [making pantingsound] bell, food, [another panting sound]" and now "bell [panting]."But next you get "bell, bell, bell." You give it up. You stop. You stopresponding to the bell. A weird thing which is discussed in thetextbook is if you wait a while and then you try it again with the bellafter a couple of hours, the saliva comes back. This is known asspontaneous recovery.心理学空间X W2UPn,~

)?u.F4u6R0So, this all seems a very technical phenomena related to animals andthe like but it's easy to see how it generalizes and how it extends.One interesting notion is that of stimulus generalization. And stimulusgeneralization is the topic of one of your articles inThe NortonReader, the one by Watson, John Watson, the famous behaviorist, whoreported a bizarre experiment with a baby known as Little Albert. Andhere's the idea. Little Albert originally liked rats. In fact, I'mgoing to show you a movie of Little Albert originally liking rats. See.[pointing to video] He's okay. No problem. Now, Watson did somethinginteresting. As Little Albert was playing with the rat, "Oh, I likerats, oh," Watson went behind the baby--this is the--it's in thechapter--and banged the metal bar right here [simulating a bangingmotion]. The baby, "Aah," screamed, started to sob. Okay. What's theunconditioned stimulus? Somebody. The loud noise, the bar, the bang.What's the unconditioned response? Crying, sadness, misery. And as aresult of this, Little Albert grew afraid of the rat. So there--whatwould be the conditioned stimulus? The rat. What would be theconditioned response? Fear. Excellent.心理学空间-T[8{8o#L%Y:Z-x[k"l

J1YRZ+X(j^,G9rO0Moreover, this fear extended to other things. So, this is a veryweird and unpersuasive clip. But the idea is--the clip is to make thepoint that the fear will extend to a rabbit, a white rabbit. So, thefirst part, Little Albert's fine with the white rabbit. The second partis after he's been conditioned and he's kind of freaked out with thewhite rabbit. The problem is in the second part they're throwing therabbit at him but [looking at the video] now he's okay. [laughter]心理学空间-oH;j4Whu'n

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[Speaking to a teaching assistant] Is the mic on? Oh. This isfine.

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This is one of a long list of experiments that we can't do anymore.So, classical conditioning is more than a laboratory phenomena. Thefindings of classical conditioning have been extended and replicated inall sorts of animals including crabs, fish, cockroaches and so on. Andit's been argued to be an extension of--it's argued to underlie certaininteresting aspects of human responses.


)H B6u#n#K0O7^0So, I have some examples here. One example is fear. So, the LittleAlbert idea--The Little Albert experiment, provides an illustration forhow phobias could emerge. Some proportion of people in this room havephobias. Imagine you're afraid of dogs. Well, a possible story forthe--for why you became afraid of dogs is that one day a dog came upand he was a neutral stimulus. No problem. And all of a sudden he bityou. Now the pain of a bite, being bit, and then the pain and fear ofthat is an unconditioned stimulus, unconditioned response. You're justborn with that, "ow." But the presence of the dog there is aconditioned stimulus and so you grew to be afraid of dogs.心理学空间 T)cs`1j[-W y}
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If you believe this, this also forms the basis for ways for a theoryof how you could make phobias go away. How do you make conditionedstimulus, conditioned response things go away? Well, what you do is youextinguish them. How do you extinguish them? Well, you show the thingthat would cause you to have the fear without the unconditionedstimulus. Here's an illustration. It's a joke. Sorry. [pointing towardsa slide containing a comic of a man trapped in a small booth, filledwith snakes, dangling from the top of a building] He's simultaneouslyconfronting the fear of heights, snakes, and the dark because he'strapped in that thing and the logic is--the logic of--the logic is notbad. 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 iswhile he's stuck in there he has this screaming, horrific panic attackand then it makes his fear much worse.心理学空间 a nfk,vC'fL7ox

?)h;y{ \ u%G/R L0So, what they do now though, and we'll talk about this much later inthe course when we talk about clinical psychology--but one cure forphobias does draw upon, in a more intelligent way, the behavioristliterature. So, the claim about a phobia is that there's a badassociation between, say dog and fear, or between airplanes or snakesand some bad response. So, what they do is what's called, "systematicdesensitization," which is they expose you to what causes you the fearbut they relax you at the same time so you replace the aversiveclassical conditioned fear with something more positive. Traditionally,they used to teach people relaxation exercises but that proves toodifficult. So nowadays they just pump you full of some drug to get youreally happy and so you're really stoned out of your head, you're[makes "sick" noise] and this isn't so bad. It's more complicated thanthat but the notion is you can use these associative tools perhaps todeal with questions about fear, phobias and how they go away.心理学空间 K3d;m|.Y,P{

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Hunger. We'll spend some time in this course discussing why we eatand when we eat. And one answer to why we eat and when we eat is thatthere's cues in the environment that are associated with eating. Andthese cues generate hunger. For those of you who are trying to quitsmoking, you'll notice that there's time--or to quit drinking there'stimes of the day or certain activities that really make you want tosmoke or really make you want to drink. And from a behaviorist point ofview this is because of the associative history of these things.

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More speculatively, classical conditioning has been argued to beimplicated in the formation of sexual desire, including fetishes. So abehaviorist story about fetishes, for instance, is it's straightforwardclassical conditioning. Just as your lover's caress brings you toorgasm, your eyes happen to fall upon a shoe. Through the simple toolsof classical conditioning then, the shoe becomes a conditioned stimulusgiving rise to the conditioned response of sexual pleasure. This almostcertainly is not the right story but again, just as in phobias, someideas of classical conditioning may play some role in determining whatwe like and what we don't like sexually. And in fact, one treatment forpedophiles and rapists involved controlled fantasies duringmasturbation to shift the association from domination and violence, forinstance, to develop more positive associations with sexual pleasure.So the strong classical conditioning stories about fetishes and fearssound silly and extreme and they probably are but at the same timeclassical conditioning can be used at least to shape the focus of ourdesires and of our interests.


Final thought actually is--Oh, yeah. Okay. So, what do we thinkabout classical conditioning? We talked about what habituation is for.What's classical conditioning for? Well, the traditional view is it'snot for anything. It's just association. So, what happens is the UCS[unconditioned stimulus] and the CS [conditioned stimulus], the belland the food, go together because they happen at the same time. And soclassical conditioning should be the strongest when these two aresimultaneous and the response to one is the same as the response to theother. This is actually no longer the mainstream view. The mainstreamview is now a little bit more interesting. It's that what happens inclassical conditioning is preparation. What happens is you becomesensitive to a cue that an event is about to happen and that allows youto prepare for the event. This makes certain predictions. It predictsthat the best timing is when the conditioned stimulus, which is thesignal, comes before the unconditioned stimulus, which is what you haveto prepare for. And it says the conditioned response may be differentfrom the unconditioned response.心理学空间R0k!u&BQ+L y

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So, move away from food. Imagine a child who's being beaten by hisfather. And when his father raises his hand he flinches. Well, that'sclassical conditioning. What happened in that case is he has learnedthat the raising of a hand is a signal that he is about to be hit andso he responds to that signal. His flinch is not the same response thatone would give if one's hit. If you're hit, you don't flinch. If you'rehit, you might feel pain or bounce back or something. Flinching ispreparation for being hit. And, in general, the idea of what goes on inclassical conditioning is that the response is sort of a preparation.The conditioned response is a preparation for the unconditionedstimulus.心理学空间7oj9q2}t

z'FQ:fC0Classical conditioning shows up all over the place. As a finalexercise, 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 andunpleasant and very violent but at its core one of the main themes isright out of Intro Psych. It's classical conditioning. And a maincharacter, who is a violent murderer and rapist, is brought in by somepsychologists for some therapy. And the therapy he gets is classicalconditioning. In particular, what happens is he is given a drug thatmakes him violently ill, extremely nauseous. And then his eyes arepropped open and he's shown scenes of violence. As a result of thissort of conditioning, he then – when he experiences real world violence– he responds with nausea and shock; basically, training him to getaway from these acts of violence.心理学空间+l0}8L1S6co p?

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In this example--Take a moment. Don't say it aloud. Just take amoment. What's the unconditioned stimulus? Okay. Anybody, what's theunconditioned stimulus? Somebody just say it. The drug. What's theunconditioned response? Nausea. What's the conditioned stimulus?Violence. What's the conditioned response? [nausea] Perfect.心理学空间!F/rD#kcl.]`^


The third and final type of learning is known as operantconditioning or instrumental conditioning. And this is the thing, thisis the theory championed and developed most extensively by Skinner.What this is is learning the relationships between what you do and howsuccessful or unsuccessful they are, learning what works and whatdoesn't. It's important. This is very different from classicalconditioning and one way to see how this is different is for classicalconditioning you don't do anything. You could literally be strappeddown and be immobile and these connections are what you appreciate andyou make connections in your mind. Instrumental conditioning isvoluntary. You choose to do things and by dint of your choices. Somechoices become more learned than others.心理学空间#Yt%y2i$g6O%Q{

U4~%nqykM0So, the idea itself was developed in the nicest form by Thorndikewho explored how animals learn. Remember behaviorists were entirelycomfortable studying animals and drawing extrapolations to otheranimals and to humans. So, he would put a cat in a puzzle box. And thetrick to a puzzle box is there's a simple way to get out but you haveto kind of pull on something, some special lever, to make it pop open.And Thorndike noted that cats do not solve this problem throughinsight. They don't sit in the box for a while and mull it over andthen figure out how to do it. Instead, what they do is they bounce allaround doing different things and gradually get better and better atit.心理学空间cG$j-jc et-@


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 oftheir behaviors is pressing the lever. The lever gets them out of thebox, but after more and more trials they stopped scratching at thebars, pushing at the ceiling and so on. They just pressed the lever.And if you graph it, they gradually get better and better. They throwout all of these behaviors randomly. Some of them get reinforced andthose are the ones that survive and others don't get reinforced andthose are the ones that go extinct.心理学空间Q3\#O(G)d#B\

[7xO/W/C)~0And it might occur to some of you that this seems to be an analogywith the Darwinian theory of natural selection where there's a randomassortment of random mutations. And sexual selections give rise to ahost of organisms, some of which survive and are fit and others whicharen't. And in fact, Skinner explicitly made the analogy from thenatural selection of species to the natural selection of behavior. Sothis could be summarized as the law of effect, which is a tendency toperform – an action's increased if rewarded, weakened if it's not. AndSkinner extended this more generally.心理学空间 u`NkeW


So, to illustrate Skinnerian theory in operant conditioning I'llgive an example of training a pig. So here is the idea. You need totrain a pig and you need to do so through operant conditioning. So oneof the things you want to do is--The pig is going to do some things youlike 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 fordoing good things. Suppose you want the pig to walk forward. So, youreinforce the pig for walking forward and you punish the pig forwalking backward. And if you do that over the fullness of time, yourreinforcement and punishment will give rise to a pig who walksforward.

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[e\'tgCD I0There's two--One technical distinction that people love to put onIntro Psych exams is that the difference between positive reinforcementand negative reinforcement. Reinforcement is something that makes thebehavior increase. Negative reinforcement is very different frompunishment. Negative reinforcement is just a type of reward. Thedifference is in positive reinforcement you do something; in negativereinforcement you take away something aversive. So, imagine the pig hasa heavy collar and to reward the pig for walking forward you mightremove the heavy collar.

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8o*v @/B:V$Kh:y0So, these are the basic techniques to train an animal. But it's kindof silly because suppose you want your pig to dance. You don't justwant your pig to walk forward. You want your pig to dance. Well, youcan't adopt the policy of "I'm going to wait for this pig to dance andwhen it does I'm going to reinforce it" because it's going to take youa very long time. Similarly, if you're dealing with immature humans andyou want your child to get you a beer, you can't just sit, wait for thekid 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 yourway to it is known as shaping.心理学空间V] l Q-@#U

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So, here is how to get a pig to dance. You wait for the pig to dosomething that's halfway close to dancing, like stumbling, and youreward it. Then it does something else that's even closer to dancingand you reward it. And you keep rewarding it as it gets closer tocloser. 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 hewalks to the kitchen and then he forgets why he's there and you run outthere. "You're such a good kid. Congratulations. Hugs." And then youget him to--and then finally you get him to also open up therefrigerator and get the beer, open the door, get the--and in that wayyou can train creatures to do complicated things.心理学空间apW a5H ogtt

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Skinner had many examples of this. Skinner developed, in World WarII, a pigeon guided missile. It was never actually used but it was agreat idea. And people, in fact--The history of the military in theUnited States and other countries includes a lot of attempts to getanimals like pigeons or dolphins to do interesting and deadly thingsthrough various training. More recreational, Skinner was fond ofteaching animals to play Ping-Pong. And again, you don't teach ananimal to play Ping-Pong by waiting for it to play Ping-Pong and thenrewarding it. Rather, you reward approximations to it.心理学空间d/_m4TN*z2y3Nt

d5^v vTj2]m8g(K:kG0And basically, there are primary reinforcers. There are some thingspigs naturally like, food for instance. There are some things pigsactually automatically don't like, like being hit or shocked. But inthe real world when dealing with humans, but even when dealing withanimals, we don't actually always use primary reinforcers or negativereinforcers. What we often use are things like--for my dog saying,"Good dog." Now, saying "Good dog" is not something your dog has beenbuilt, pre-wired, to find pleasurable. But what happens is you can do atwo-step process. You can make "Good dog" positive through classicalconditioning. You give the dog a treat and say, "Good dog." Now thephrase "good dog" will carry the rewarding quality. And you could usethat rewarding quality in order to train it. And through this waybehaviorists have developed token economies where they get nonhumananimals to do interesting things for seemingly arbitrary rewards likepoker chips. And in this way you can increase the utility and ease oftraining.心理学空间s(ZQ9Z0Aun E.t

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Finally, in the examples we're giving, whenever the pig doessomething you like you reinforce it. But that's not how real lifeworks. Real life for both humans and animals involved cases where thereinforcement doesn't happen all the time but actually happensaccording to different schedules. And so, there is the distinctionbetween fixed schedules versus ratios – variable schedules and ratioversus 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 areward every certain number of times somebody does something. So, ifevery tenth time your dog brought you the newspaper you gave it hugsand treats; that's ratio. An interval is over a period of time. So, ifyour dog gives you--if your dog, I don't know, dances for an hourstraight, that would be an interval thing. And fixed versus variablespeaks to whether you give a reward on a fixed schedule, every fifthtime, or variable, sometimes on the third time, sometimes on theseventh time, and so on.

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And these are--There are examples here and there's no need to goover them. It's easy enough to think of examples in real life. So, forexample, a slot machine is variable ratio. It goes off after it's beenhit a certain number of times. It doesn't matter how long it takes youfor--to do it. It's the number of times you pull it down. But it'svariable because it doesn't always go off on the thousandth time. Youdon't know. It's unpredictable. The slot machine is a good example of aphenomena known as the partial reinforcement effect. And this is kindof neat. It makes sense when you hear it but it's the sort of findingthat's been validated over and over again with animals and nonhumans.Here's the idea. Suppose you want to train somebody to do something andyou want the training such that they'll keep on doing it even if you'renot training them anymore, which is typically what you want. If youwant that, the trick is don't reinforce it all the time. Behaviors lastlonger if they're reinforced intermittently and this is known as "thepartial reinforcement effect."心理学空间4Q#m\|;\mW

J$UvY.kO0Thinking of this psychologically, it's as if whenever you putsomething in a slot machine it gave you money, then all of a sudden itstopped. You keep on doing it a few times but then you say, "Fine. Itdoesn't work," but what if it gave you money one out of every hundredtimes? Now you keep on trying and because the reinforcement isintermittent you don't expect it as much and so your behavior willpersist 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 bedwith you and you don't want him to go into bed with you? Well, one--Theworst thing to do is for any--Actually, for any form of discipline witha kid is to say, "No, absolutely not. No, no, no, no." [pause] "Okay."And then later on the kid's going to say, "I want to do it again" andyou say no and the kid keeps asking because you've put it, well, put itas 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 tokeep on asking. And so typically, what you're doing inadvertently inthose 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 tentimes. Unfortunately, that's the evolution of nagging. Because you nag,you nag, you nag, the person says, "Fine, okay," and that reinforcesit.

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$b(s,dzi w%{0If Skinner kept the focus on rats and pigeons and dogs, he would nothave the impact that he did but he argued that you could extend all ofthese notions to humans and to human behavior. So for an example, heargued that the prison system needs to be reformed because instead offocusing on notions of justice and retribution what we should do isfocus instead on questions of reinforcing good behaviors and punishingbad ones. He argued for the notions of operant conditioning to beextended to everyday life and argued that people's lives would becomefuller and more satisfying if they were controlled in a properlybehaviorist way. Any questions about behaviorism? What are yourquestions about behaviorism? [laughter] Yes.心理学空间plz)R C+f"EE{9z


Student: [inaudible]--wouldn't there be extinction after awhile? [inaudible]

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Professor Paul Bloom: Good question. The discussion was overusing things like poker chips for reinforcement and the point isexactly right. Since the connection with the poker chips is establishedthrough classical conditioning, sooner or later by that logic the pokerchips would lose their power to serve as reinforcers. You'd have tosort 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 somepoint 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.心理学空间p@8Snp8_d`QhB4I

3l/Z/B1eV0Student: [inaudible]心理学空间0\/w YbD)@\] G)k

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Professor Paul Bloom: As far as I know, Skinner andSkinnerian psychologists were never directly involved in the creationof prisons. On the other hand, the psychological theory of behaviorismhas had a huge impact and I think a lot of people's ways of thinkingabout criminal justice and criminal law has been shaped by behavioristprinciples. So for instance, institutions like mental institutions andsome prisons have installed token economies where there's rewards forgood behavior, often poker chips of a sort. And then you could cashthem in for other things. And, to some extent, these have been shapedby an adherence to behaviorist principles.心理学空间{sU9t6B

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Okay. So, here are the three general positions of behaviorism. (1)That there is no innate knowledge. All you need is learning. (2) Thatyou could explain human psychology without mental notions like desiresand goals. (3) And that these mechanisms apply across all domains andacross all species. I think it's fair to say that right now just abouteverybody agrees all of these three claims are mistaken.

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5n6DYf/T%m0First, we know that it's not true that everything is learned. Thereis considerable evidence for different forms of innate knowledge andinnate desires and we'll look--and we'll talk about it in detail whenwe look at case studies like language learning, the development ofsexual preference, the developing understanding of material objects.There's a lot of debate over how much is innate and what the characterof the built-in mental systems are but there's nobody who doubtsnowadays that a considerable amount for humans and other animals isbuilt-in.心理学空间%\z W#h)Y


Is it true that talking about mental states is unscientific? Nobodybelieves this anymore either. Science, particularly more advancedsciences like physics or chemistry, are all about unobservables.They're all about things you can't see. And it makes sense to explaincomplex and intelligent behavior in terms of internal mechanisms andinternal representations. Once again, the computer revolution hasserved as an illustrative case study. If you have a computer that playschess and you want to explain how the computer plays chess, it'simpossible to do so without talking about the programs and mechanismsinside the computer.

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Is it true that animals need reinforcement and punishment to learn?No, and there's several demonstrations at the time of Skinnersuggesting that they don't. This is from a classic study by Tolmanwhere rats were taught to run a maze. And what they found was the ratsdid fine. They learn to run a maze faster and faster when they'reregularly rewarded but they also learn to run a maze faster and fasterif they are not rewarded at all. So the reward helps, but the reward isin no sense necessary.


Z d\vq0And here's a more sophisticated illustration of the same point.[Professor Bloom plays video]心理学空间K2j1gs/V


Professor Paul Bloom: And this is the sort of finding, an oldfinding from before most of you were born, that was a hugeembarrassment for the Skinnerian theory, as it suggests that rats infact had mental maps, an internal mechanism that they used tounderstand the world – entirely contrary to the behaviorist ideaeverything could be explained in terms of reinforcement andpunishment.

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Finally, is it true that there's no animal-specific constraints forlearning? And again, the answer seems to be "no." Animals, forinstance, have natural responses. So, you could train a pigeon to peckfor food but that's because pecking for food is a very naturalresponse. It's very difficult to train it to peck to escape asituation. You can train it to flap its wings to escape a situation butit's very difficult to get it to flap its wings for food. And the ideais they have sort of natural responses that these learning situationsmight exploit and might channel, but essentially, they do have certainnatural ways of acting towards the world.

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We know that not all stimuli and responses are created equal. So,the Gray textbook has a very nice discussion of the Garcia effect. Andthe Garcia effect goes like this. Does anybody here have any foodaversions? I don't mean foods you don't like. I mean foods that reallymake you sick. Often food aversions in humans and other animals can beformed through a form of association. What happens is suppose you havethe flu and you get very nauseous and then at the same point you eatsome sashimi for the first time. The connection between being nauseousand eating a new food is very potent. And even if you knowintellectually full well that the sashimi isn't why you becamenauseous, still you'll develop an aversion to this new food.


When I was younger – when I was a teenager – I drank this Greekliqueur, ouzo, with beer. I didn't have the flu at the time but Ibecame violently ill. And as a result I cannot abide the smell of thatGreek liqueur. Now, thank God it didn't develop into an aversion tobeer but-- [laughter] Small miracles. But the smell is very distinctiveand for me--was new to me. And so, through the Garcia effect Ideveloped a strong aversion.

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What's interesting though is the aversion is special so if you takean animal and you give it a new food and then you give it a drug tomake it nauseous it will avoid that food. But if you take an animal andyou give it a new food and then you shock it very painfully it won'tavoid the new food. And the idea is that a connection between whatsomething 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 isspecial to taste and nausea. It doesn't extend more generally.

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Finally, I talked about phobias and I'll return to phobias later onin this course. But the claim that people have formed their phobiasthrough classical conditioning is almost always wrong. Instead, itturns out that there are certain phobias that we're specially evolvedto have. So, both humans and chimpanzees, for instance, areparticularly prone to develop fears of snakes. And when we talk aboutthe emotions later on in the course we'll talk about this in moredetail. But what seems likely is the sort of phobias you're likely tohave does not have much to do with your personal history but rather ithas a lot to do with your evolutionary history.心理学空间z5?FP1v{

-C6X!_4hck.P c1i3Dy0Finally, the other reading you're going to do for this part--sectionof the course is Chomsky's classic article, his "Review of VerbalBehavior." 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 influentialintellectual documents ever written in psychology because it took theentire discipline of behaviorism and, more than everything else, morethan any other event, could be said to have destroyed it or ended it asa dominant intellectual endeavor.

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+d'dI`;n e_6d0c0And Chomsky's argument is complicated and interesting, but the mainsort of argument he had to make is--goes like this. When it comes tohumans, the notions of reward and punishment and so on that Skinnertried to extend to humans are so vague it's not science anymore. Andremember the discussion we had with regard to Freud. What Skinner--WhatChomsky is raising here is the concern of unfalsifiablity. So, here'sthe sort of example he would discuss. Skinner, in his bookVerbalBehavior, talks about the question of why do we do things like talkto ourselves, imitate sounds, create art, give bad news to an enemy,fantasize about pleasant situations? And Skinner says that they allinvolve reinforcement; those are all reinforced behaviors. But Skinnerdoesn't literally mean that when we talk to ourselves somebody gives usfood pellets. He doesn't literally mean even that when we talk toourselves 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 enemyis reinforcing because it makes your enemy feel bad.心理学空间 orPQx@


Well, Chomsky says the problem is not that that's wrong. That's alltrue. It's just so vague as to be useless. Skinner isn't sayinganything more. To say giving bad news to an enemy is reinforcingbecause it makes the enemy feel bad doesn't say anything different fromgiving bad news to an enemy feels good because we like to give bad newsto an enemy. It's just putting it in more scientific terms.

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More generally, Chomsky suggests that the law of effect when appliedto humans is either trivially true, trivially or uninterestingly true,or scientifically robust and obviously false. So, if you want to expandthe notion of reward or reinforcement to anything, then it's true. Sowhy did you come--those of you who are not freshmen--Oh, you--Why didyou 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 thatsomebody rewarded you, gave you pellets and stuff. What you mean is youchose to come there for the second semester. And there's nothing wrongwith saying that but we shouldn't confuse it with science. And moregenerally, the problem is you can talk about what other people do interms of reinforcement and punishment and operant conditioning andclassical conditioning. But in order to do so, you have to use termslike "punishment" and "reward" and "reinforcement" in such a vague waythat in the end you're not saying anything scientific.心理学空间GlB#E(} oF/\X

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So, behaviorism as a dominant intellectual field has faded, but itstill leaves behind an important legacy and it still stands as one ofthe 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 bescientifically studied; and they play an important role in the lives ofanimals and probably an important role in human lives as well. Theyjust don't explain everything. Finally, and this is something I'm goingto return to on Wednesday actually, behaviorists have provided powerfultechniques for training particularly for nonverbal creatures so thisextends to animal trainers. But it also extends to people who want toteach young children and babies and also want to help populations likethe severely autistic or the severely retarded. Many of thesebehaviorist techniques have proven to be quite useful. And in thatregard, as well as in other regards, it stands as an importantcontribution.心理学空间k(l6v6EW/t

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[end of transcript]

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