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  • Professor Paul Bloom: Two follow-ups on

  • yesterday's--I'm sorry, on Monday's lecture.

  • One is that somebody came up after class and asked when the

  • preference for your own language emerges in development and

  • fortunately, studies pretty much exactly

  • this sort of infant understanding.

  • She knew the answer. There's been studies looking at

  • newborn babies finding that pretty much the moment they pop

  • out they favor their own language over other

  • language--over other languages. And this suggests that they are

  • listening while in utero, while in the womb,

  • to the rhythms of their language and developing a

  • preference for it. A second issue is,

  • I talked very briefly about a court case in which the person

  • was--said at a moment where someone else was pointing a gun

  • at a police officer, "Let him have it!"

  • and a police officer was killed. And that person was charged

  • with murder but I admitted I didn't actually know how things

  • turned out and was kind enough to do extensive research.

  • Well, he went to Wikipedia and [laughter]

  • found out the answer. The answer is he was tried and

  • found guilty for murder. He was then subsequently

  • pardoned. In fact, he was pardoned in

  • 1988, which is really nice except he was executed in 1957.

  • But they did it into a movie. So, it's a movie.

  • Okay. So, I want to do today,

  • for the first part of the lecture, is continue the

  • language lecture and then move to perception,

  • attention, and memory. And what we had spoken about

  • was--We first talked about universals of language,

  • then moved to some detail about the different aspects of

  • language including phonology, morphology, and syntax.

  • We discussed the ways in which language does the amazing things

  • it does, including the fact that language has used arbitrary

  • science or sounds to convey concepts,

  • and that languages exploit a combinatorial system including

  • recursion to put together these symbols into a virtually

  • limitless set of meaningful sentences.

  • We then talked about development and made some

  • remarks about the developmental time coursetalking about

  • the emergence of language from babies towhere babies are

  • really good at learning language to you who are not,

  • whose brains have atrophied, whose language capacities are

  • dead. Final issue is to shift to

  • animals. Now that we know something

  • about language, we could then ask do animals

  • use--possess the same sort of language?

  • And if not, can they learn it? Now, there is absolutely no

  • doubt at all that nonhuman animals possess communication

  • systems. This has been known forever and

  • is not a matter of controversy. And if you want to use the term

  • "language" to mean "communication," then the answer

  • is obviously "yes." Dogs and bees and monkeys have

  • language. If you want to use language

  • though in the more technical, narrow sense as anything that

  • has the properties that we discussed earlier,

  • using English and ASL and Spanish and so on as our

  • background, the answer's almost certainly "no."

  • Animal communication systems fall into sort of one of three

  • categories. Either there is a finite list

  • of calls, so vervet monkeys, for instance,

  • have a small list of calls to convey different warnings like

  • "attack from a snake" or "attack from a leopard."

  • There is a continuous analog signal.

  • So, bee dance, for instance,

  • works on this way. Bee dance communicates the

  • location of food sources but doesn't do it in any

  • syntactically structured way. Rather, the intensity of the

  • dance corresponds to the richness of the food source.

  • And then, you get things like random variation on a theme such

  • as birdsong. But what you don't find in any

  • real sense is phonology, morphology, syntax,

  • combinatorial systems or arbitrary names.

  • Now, this much is not particularly controversial.

  • There gets to be a lot of controversy though.

  • This is the summary about nonhuman communication systems.

  • It gets more controversial when we get to famous cases of

  • primates trained by humans such as Kanzi,

  • Nim Chimpsky, and other famous primates that

  • you may well have seen on the Discovery channel and other

  • venues. And this is fairly

  • controversial. If you read the Gray textbook,

  • while nothing in it is particularly inaccurate,

  • I think Gray is actually a little bit too credulous,

  • too believing in the claims that have been made about the

  • abilities of the animals. So many scientists argue,

  • for instance, that animals like Kanzi,

  • even if they can be said to be learning words at all,

  • learn very few of them. And it takes them extensive

  • years of training to learn, unlike a normally developing

  • child who could learn a word in a day or a word in an hour.

  • The utterances often have order but this order tends to be very

  • limited and lacks the recursive properties.

  • And in fact, the lack of recursion is not

  • controversial. Finally, the utterances of

  • chimpanzees--trained chimpanzees are extremely repetitive so what

  • you often see on TV and in documentaries is sort of a

  • sampling. And the sampling could often be

  • very impressive but if you take just what they say at random it

  • tends to look like this. This is typical chimpanzee

  • utterances just taken at random: "Nim eat, Nim eat.

  • Drink, eat, me Nim. Me gum, me gum.

  • Tickle me, Nim play. Me eat, me eat.

  • Me banana, you banana, me you give.

  • Banana me, me eat. Give orange,

  • me give, eat orange, me eat orange."

  • Lila Gleitman once commented that if any normally developing

  • child spoke like this, his parents would rush him

  • screaming to a neurologist. There's a broader question

  • here, which is, "Why would we ever expect a

  • chimpanzee to learn a human language?"

  • We don't normally expect one species to have the capacities

  • associated with another species. So, bats use echolocation to

  • get around and some birds navigate by the stars,

  • but there's not an active research program seeing if cats

  • can use echolocation or dogs could navigate by the stars.

  • And I think one reason why you might be tempted to think,

  • "well, of course chimps must be able to learn language" is

  • because you might be caught in the grips of some bad ideas

  • about language. So, one idea is you might say,

  • "Look. Chimps should use language

  • because chimps are so smart." But the response to this is,

  • "they are smart but we know that smart isn't enough."

  • We know that the human capacity for language is not totally a

  • result of smartness. There are smart children who,

  • due to some deficit in their language capacity,

  • don't speak or understand a language.

  • So, the smartness of chimpanzees does not in itself

  • demonstrate that they should be able to learn language.

  • You might also point out correctly that chimps are our

  • nearest evolutionary relatives, which is right,

  • so you--one would expect on the face of it--it's not

  • unreasonable to expect us to share a lot of abilities with

  • them. On the other hand,

  • we split from them a long time ago and plainly humans are

  • different from chimps. And there was five million

  • years either way and that's more than enough time for a language

  • capacity to evolve. Now, none of this is to say

  • that the study of nonhuman communication systems isn't

  • interesting. From my own--This is my

  • personal opinion I'll raise here.

  • From my own opinion, the study of the attempts to

  • try to teach chimpanzees, or gibbons, or gorillas,

  • a human language like ASL are misguided.

  • It would be as if a team of monkeys kidnapped a human child

  • and tried to train him how to hoot like a monkey.

  • It might be enjoyable but it does not seem to give us any

  • rich insights. What I think is a lot more

  • interesting is the study of these animal communication

  • systems in the wild. There's a linguistics of human

  • language that has delineated the principles that underlie all

  • human languages. It would be as extraordinarily

  • interesting to attempt the same linguistic program to the other

  • communication systems used in the wild such as the cries of

  • vervet monkeys and bee dance. So, this brings the section on

  • language to a close but I want to tell you a few things we

  • didn't talk about. One of the problems with an

  • Intro Psych course is we have to whip through a lot of topics

  • very fast. So, if you were to take a

  • course that focused directly on language you might learn,

  • for instance, more about language in the

  • brain, something touched about very briefly in the textbook but

  • something that has a large literature associated with it.

  • Similarly, and related to this, there's language disorders,

  • disorders like aphasias and disorders like specific language

  • impairment and dyslexia. There is the study of language

  • perception and production. How is it that we do this

  • amazing feat of understanding and producing words in a

  • fraction of a second? Where does that ability come

  • from? There is the study of reading

  • which is, in many ways, different from the study of a

  • language. Remember when Darwin described

  • language as an instinct. He carefully distinguished it

  • from other things that don't come natural to us including

  • reading. And in fact,

  • reading is difficult. Reading is a cultural

  • invention, not every human has it.

  • And unlike language, reading is acquired with

  • tremendous difficulty over many years.

  • On the other hand, reading plainly intersects with

  • language. It's a new way of conveying

  • language, moving out from speech to writing.

  • And the psychology and neuroscience of reading is thus

  • very interesting. There's bilingualism and

  • multilingualism. The questions people in this

  • room typically are going to be interested in is does it matter

  • for how well you learn language whether you're learning one or

  • two or three or four. How is it that a multilingual

  • encodes all these different languages inside a single brain?

  • And so on. Finally, a very hot issue is

  • that of the relationship between language and thought and I'm

  • actually--A few years ago I taught an entire seminar called

  • "Language and Thought" devoted to precisely this question.

  • And it's a cool question and it could break up into two very

  • general questions. One is, "Is language necessary

  • for abstract thought?" And one way to answer that

  • question is to look at creatures without language like babies and

  • chimpanzees and see how smart they are.

  • It might be that they're not--that they're very smart,

  • in which case it would suggest you don't need language for

  • abstract thought. On the other hand,

  • it might be that they have certain cognitive limitations,

  • which would suggest that language is essential for

  • abstract thought. Then there's the related

  • question. Even once you know a language,

  • does the structural properties of the language that you know

  • affect the way you think? And the claim that the language

  • you know affects how you think is sometimes described as

  • linguistic relativity or the Sapir-Whorf hypothesis.

  • So for instance, there's a lot of research

  • looking at speakers of different languages such as English versus

  • Korean and seeing whether structural differences in these

  • languages affect how you think. Now, some of this work is

  • discussed in the readings, the book--the Gray textbook,

  • and the selections from The Norton Anthology. And this

  • makes up--again, I've showed this to you on

  • Monday--your reading response where you have to address this

  • question and take your best shot at answering it.

  • What are your questions about language?

  • Yes. Student: [inaudible]

  • Professor Paul Bloom: The question was raised,

  • "Some people learn languages easier than others and how do we

  • explain this?" And the answer is you could ask

  • the question both with regard to first language learningso

  • some children learn language very quickly,

  • some are very slowand also with regard to second language

  • learning. Some of you are breezing

  • through your second language requirement here at Yale.

  • Others are struggling and miserable.

  • And there's considerable variation.

  • There's the story of Einstein who was very slow to learn

  • language and didn't speak at all until he was four.

  • And in fact, he was a--He said his first

  • words when all of a sudden he was having supper with his

  • parents and he put down the spoon and he said,

  • "The soup is too hot." And his parents stared in

  • astonishment and said, "You've never spoken before."

  • And he said, "Well, up to now everything's

  • been fine." [laughter]

  • It's not a true story. [laughter]

  • The question of why and where these differences come from,

  • nobody really knows and it's surprisingly hard.

  • There's a slight advantage for being female.

  • Girls are slightly more advanced in language than boys

  • but it's not a big one and you need a hundred people to just

  • see it statistically. There's a big genetic factor.

  • If your parents learned language quickly and learned

  • other languages quickly, you are more likely to.

  • But an understanding of the brain bases of these differences

  • or the cognitive bases or the social bases is just--is largely

  • an open question. Yes.

  • Student: What happens when parents [inaudible]

  • Professor Paul Bloom: This is actually more the norm

  • around the world than the situation in the United States

  • where kids are exposed to a single language.

  • What happens is children learn both languages.

  • Children are very good, as adults are,

  • of distinguishing different languages on the basis of their

  • sound system and their rhythms so they don't typically confuse

  • them. And then they just learn more

  • than one language. And that's actually more the

  • average state of affairs around the world.

  • Yes. Student: You said that

  • people who are right-handed learn languages [inaudible]

  • Professor Paul Bloom: The question is about the

  • hemispheric specialization for language.

  • And I don't have actually much more to say than what I said

  • before, which I agree is deeply unsatisfying.

  • If you're right-handed, language is probably in the

  • left side of your brain. How many people here are

  • left-handed? For you we don't know.

  • It varies. Some of you have it in the left

  • side. Some of you have it in the

  • right side. For some of you it's kind of

  • diffuse. Now, why is this?

  • And in fact, why are some people

  • right-handed and others left-handed in the first place?

  • Those are really good questions. Yes.

  • Student: [inaudible] Professor Paul Bloom:

  • Yes. I'll--Yes, that's--I'll answer

  • that question. And unfortunately,

  • it's going to be the last one and then I'll go to vision.

  • The question is, "Does learning more than one

  • language cause you to learn them slower than just learning one

  • language?" And it would stand to reason

  • that it would. There's a finite amount of

  • mental resources. If I'm just learning English,

  • I use all of it for English. And if I'm learning English and

  • Spanish I kind of got to split. And you'd expect them to be

  • each learned slower. It's one of the surprises of

  • the study of language development that that

  • common-sense view does not appear to be true.

  • Children learning more than one language seem to show no deficit

  • relative--in each of their languages, relative to a child

  • learning just one language. In other words,

  • if I am just learning English and I'm a kid and you're

  • learning English and Spanish and you're a kid,

  • you'll reach the milestones in English the same time I will.

  • Your extra learning of Spanish doesn't seem to affect you.

  • There doesn't seem to be any detriment for learning multiple

  • languages. Another question which comes up

  • is, "Is there any cognitive deficit?"

  • In other words, some people have argued that

  • learning multiple languages sometimes harms children in

  • certain ways. This is a claim that's been

  • made in Quebec, for instance,

  • over the debate over how children should be taught

  • English and French. It does not appear to be the

  • case. There appears to be,

  • as far as we know, no down side to learning many

  • languages when you're young. Does that answer your question?

  • I want to move now to the topic that will take us through today

  • and through the beginning of next weekperception,

  • attention, and memory. And I'm putting them together

  • instead of treating them as separate lectures because

  • there's a sense in which they're the same story.

  • You see a scene. You see this scene and you're

  • looking at it and you're perceiving it.

  • It's coming through your eyes and you're interpreting it and

  • you see something. You see a man and you see a

  • house. If you were to shut your eyes,

  • you could still hold that scene in memory.

  • And a week later, if I'm to ask you about that,

  • "What season was it?" you would do pretty well.

  • This is the story I want to talk abouthow we do this.

  • And in the course of this I want to make a series of claims

  • that go something like this. For perception,

  • I want to first persuade you the problem of perception's hard

  • and that successful perception involves educated and

  • unconscious guesses about the world.

  • For attention, I want to suggest that we

  • attend to some things and not others and we miss a surprising

  • amount of what happens in the world.

  • For memory, there are many types of memory.

  • The key to memory is organization and understanding.

  • And you can't trust some of your memories.

  • How many of you remember where you were at 9/11?

  • Many of you are wrong. And I am never going to

  • persuade you of this because you have certain memories.

  • And you could tell the story. Everybody could tell the story

  • where they were when the towers went down.

  • But clever psychologists on September 12 said,

  • "Let's do a study." And they asked people,

  • "Where were you yesterday when you heard the news?"

  • And they told them. And then they went back to them

  • later, a year later, two years later,

  • and said, "Tell me about what happened September 11."

  • And they said, "I remember totally where I

  • was. I have a very--" And then--And

  • often the story was wrong. There is a lot like that which

  • we're going to talk about. And the biggest moral then--so,

  • I put it really, in really big print--We are

  • often wrong about our experiences, both of the present

  • and of right now. So, let's start with perception.

  • There is a story--I went to graduate school at MIT and there

  • was a story there about Marvin Minsky who is the A.I.

  • guru. He--If you've heard the

  • words--the phrase "artificial intelligence," that was him.

  • And if you heard the claim that people are nothing more than

  • machines made of meat--also him. Well, there's a story where he

  • was doing work on robotics and he was interested in building a

  • robot that could do all sorts of cool things that's like a robot.

  • And the story goes the robot had to among--had to write--had

  • to see the world. It had to be able to pick up

  • things and recognize people and see chairs and navigate its way

  • and Minsky said, "That's a tough problem.

  • It's going to take a graduate student a whole summer to figure

  • it out." And he assigned it to a

  • graduate student for a summer project.

  • Visual psychologists, perception psychologists,

  • love that story because the study of computer vision and

  • robotics vision and the attempts to make machines that can

  • identify and recognize objects has been a profound failure.

  • There is, at this point, no machine on earth that could

  • recognize people and objects and things at the level of a really

  • dumb one-year-old. And the reason why is that it's

  • a much harder problem than anybody could have expected.

  • Well, what makes it such a hard problem?

  • Well, one reason why you might think it's an easy problem is

  • you say, "Okay. We have to figure out the

  • problem of how people see. Well, here's what we do."

  • You're in--You're over there and here's your eye.

  • And somehow it has to get to this television monitor and then

  • you look at it and that'll solve the problem of how you see.

  • So, sometimes people say, "Hey. I hear the eye flips things

  • upside down. I guess this guy is going to

  • have to get used to looking at things upside down.

  • That's an interesting problem." No.

  • That's not the way to look at it because that doesn't answer

  • any questions. That just pushes the question

  • back. Fine.

  • How does "he" see? We're not answering anything.

  • Similarly, although the Terminator's view of the world

  • may correspond to that , that doesn't solve any problem

  • of how he actually sees. So, he has all these numbers

  • shooting out there. Well, he has to read the

  • numbers. He has to see this.

  • This is my iTunes. [laughter] That's inadvertent.

  • Here's the right way to think about perception.

  • You got the eye, which is very ugly and bloody,

  • and then around here you have the retina.

  • And the retina is a bunch of nerve cells.

  • And the nerve cells fire at--for some stimulus and not

  • others. And from this array of firings,

  • "firingnot firingfiringnot firing," you have

  • to figure out what the world is. So, a better view is like this.

  • The firings of the neurons could be viewed as an array of

  • numbers. You have to figure out how to

  • get from the numbers to objects and people, and to actions and

  • events. And that's the problem.

  • It's made particularly a difficult problem because the

  • retina is a two-dimensional surface and you have to infer a

  • 3D world from a two-dimensional surface.

  • And this is, from a mathematical point of

  • view, impossible. And what this means is that

  • there--For any two-dimensional image there is an indefinite

  • number of three-dimensional images that correspond to it.

  • So for instance, suppose you have this on your

  • retina, an array of light shaped like that .

  • What does that correspond to in the world?

  • Well, it could correspond to a thing just like that that you're

  • looking for or it could correspond to a square that's

  • tilted backwards. And so, you have to figure out

  • which is which. And the way we solve this

  • problem is that we have unconscious assumptions about

  • how the world works. Our minds contain certain

  • assumptions about how things should be that enable us to make

  • educated guesses from the two-dimensional array on to the

  • three-dimensional world. And I purposefully did not make

  • the slides available for this class ahead of time because I

  • don't want people to cheat, but there are several points

  • where you could look at the slides and confirm that some of

  • the things I'm going to tell you are actually true.

  • And I want to give you three examples.

  • One is color. And I'm going to conflate here

  • color and brightness. The other is objects.

  • The other is depth. First, the problem of color.

  • How do you tell a lump of coal from a snowball?

  • Well, that's a lump of coal and that's a snowball,

  • and it's from Google images. How do you know which is which?

  • Well, a lump of coal you say is black and a snowball is white.

  • How do you know? Well, maybe you have on your

  • retina--Your retina responds to sort of color that hits it.

  • It's oversimplified, but let's assume that this is

  • true. So, this is black coming out

  • and that's white and that's how you tell.

  • But in fact, that can't be right.

  • It can't be right because objects' color is not merely a

  • matter of what material they're made of but of the amount of

  • light that hits it. So, as I walk across the stage

  • I fall into shadow and light, and none of you screams out,

  • "Professor Bloom is changing colors!"

  • Rather, you automatically factor out the change in

  • illumination as this is happening.

  • And this could actually be quite striking.

  • So, you see this display over here.

  • Take a look at those two blocks. I take it you see this one as

  • lighter than that one. You do.

  • You might imagine this is because this strip is lighter

  • than this but it isn't. They're the same.

  • And you won't believe me until you actually print it out and

  • take a look, but they are in fact the same.

  • I'll show it to you. And you could say I'm tricking

  • you but this is the way it works.

  • There's the close-up. So, remember we're comparing

  • this and this. Now, let's take away other

  • parts of the environment and you'll see they're the same.

  • Now you say, "But hold it. This can't be the same as this"

  • but the answer is--goes like this.

  • We know shadows make surfaces darker.

  • We don't know this like "Here's something I know."

  • Rather, we know this in that it's wired up in our brains.

  • So when we see a surface in shadow we automatically assume

  • that it's lighter than it looks, and we see it as lighter.

  • And you could show this by removing the cues to the shadow.

  • And you see it as it really is. And this is an illustration of

  • how the information to your eyes is just one bit of information;

  • the degree of light coming from a single source is one bit of

  • information that you use to calculate certain assumptions

  • and come to a conclusion. Here's a different kind of

  • example: Objects. You see this and you

  • automatically and intuitively segment it into different

  • objects. You segment it into a man and a

  • house and birds and trees. How do you do this?

  • It turns out, to program a computer to

  • segment a scene into different objects is hugely difficult and

  • the question of how we do it is, to some extent, unknown.

  • But one answer to this question is there are certain cues in the

  • environment that are signals that you're dealing with

  • different objects. And these cues are often

  • described as Gestalt principles. So, one example is "proximity."

  • When you see things that are close to each other,

  • you're more likely than not to assume that they belong to the

  • same thing. There's "similarity."

  • That display could correspond to an indefinite number of

  • objects but you naturally tend to see it as two.

  • You do one with one texture pattern, the other with the

  • other texture pattern. "Closure."

  • The fact that this is a closed square here suggests it's a

  • single object . "Good continuation."

  • If you had to judge, this could just as well be two

  • shapes, one that runs from A to C, the other one that runs from

  • D to B. But you don't tend to see it

  • that way. Rather, you tend to see it as

  • one that runs from A to B, the other one that runs from C

  • to D. "Common movement."

  • If things move together they're a single object.

  • And "good form." You see the object over there .

  • In the absence of any other information, you might be

  • tempted to say that's a single thing, a plus sign maybe.

  • This , because it has lousy form, you're more tempted to say

  • it's two things, one thing lying on top of each

  • other. And these are the sort of cues,

  • expectations; none of them are right.

  • There's cases where they could all fool you.

  • But these are useful cues that guide our parceling of the

  • world, our segmenting of the world into distinct objects.

  • Here they are summarized . And here's a case where they

  • fool you . So you might think,

  • if you're suggestible, that there is a triangle here.

  • And this is a case where there are certain cues driving you to

  • think that there's a triangle here.

  • There is, however, no triangle here.

  • If you cover up these little Pacmen here, the triangle goes

  • away. Similarly, there is no square

  • in the middle . There is no square.

  • It's very Matrix. And these are illusions because

  • these are cues that there should be a square there,

  • the regularity of form. Finally, "depth."

  • You see this and you don't--You see it on one level as a flat

  • thing. Another level you look inside

  • the picture and you see, for instance,

  • the man is in front of the house.

  • You look at me and you see the podium.

  • And if you have a terrible neurological disorder you see

  • this strange creature that's half podium leading on to a

  • chest and up to a head that's sort of--the top of him is

  • wiggling and the podium staying still.

  • If you are neurologically normal, you see a man walking

  • back and forth behind a podium. How do you do that?

  • Well, this is really a problem because, I could give you a

  • technical reason why vision is hard,

  • but crudely, you got a two-dimensional

  • retina and you have to figure out a three-dimensional world.

  • How do you do it? And the answer once again is

  • assumptions or cues. There are certain assumptions

  • the visual system makes that aren't always right and in fact,

  • in cases of visual illusions, can be wrong but will guide you

  • to perceive the world in a correct and accurate way.

  • So for example, there is binocular disparity.

  • This is actually a sort of interesting one.

  • This is the only depth cue that involves two eyes.

  • If I look at you pretty close, the image I get here and the

  • image I get here are somewhat different while--or I have to

  • focus my eyes together to get the same image.

  • If I look at you in back, they're almost identical

  • because the further away, given the two eyes that are

  • static, the closer the images look.

  • And it's not, again, that you say to

  • yourself, "Oh. Back there an orange.

  • It's the same image in my right eye and my left eye.

  • You must be far away." Rather, unconsciously and

  • automatically you make estimations on how far people

  • are in depth based on binocular disparity.

  • There is "interposition." How do you know I'm in front of

  • the podium and the podium's not in front of me?

  • No. How do you know the podium's in

  • front of me? Well, from where I'm standing

  • it's right. How do you know the podium is

  • in front of me? Well, because I'm walking here

  • and then it cuts into me. And unless I'm going through a

  • grotesque metamorphosis, what's happening is it makes

  • sense to say I'm moving behind the podium.

  • Interposition. You take the guy.

  • How do you know the guy is standing in front of the house?

  • Well, because there is--you see all of him and he's blocking a

  • lot of the house. There's relative size.

  • How far away am I? Well, if you looked at me and

  • you had to estimate how far away I am, part of the way you'll

  • figure that out is you know how tall a human's supposed to be.

  • If you thought that I was fifty feet tall, you would assume I'm

  • further away than I am. And so, your judgments on size

  • dictate your judgments about distance.

  • Usually, this cue isn't necessary but if you look at the

  • Empire State Building--If you go into a field and you see a tower

  • and you look, your judgment of how far away

  • the tower's going to be depends on your knowledge of how tall a

  • tower should be. If it's this tall, you say, "Oh.

  • It must be--" And then you'd be surprised.

  • There's texture gradient, which I'll explain in a second,

  • and linear perspective, which I'll also explain in a

  • second. Texture gradient goes like this.

  • Remember the problem we had before.

  • How do you know if that thing is this object or an object in

  • and of itself? Well, the answer is things with

  • textures will show themselves because the textures will get

  • smaller from a distance. Now, logically,

  • this could still be a single thing standing upright with just

  • dots going up smaller. But the natural assumption is

  • the reason why the dots recede in this regular fashion is

  • because it's receding in depth. Classic illusionthe

  • Mueller-Lyer illusion. People will see this as longer

  • than this . It's not.

  • If you don't believe me, print it out and measure it.

  • Related to the Ponzo illusion, once again people see this one

  • as--you get illusions named after you when you discover

  • these--this one as longer than this .

  • Again, it's not. What's going on here?

  • Well, the top line looks longer even though it isn't.

  • And one explanation for why is, these other lines in the scene

  • cause your visual system to make guesses about distance.

  • And then you correct for distance by making assumptions

  • about size. If you have two lines--You'll

  • get--We'll get in more detail in a second, but if you have two

  • lines and they take up the same amount of space on your retina,

  • but you believe that one is 100 feet away and the other's 50

  • feet away, the one that's 100 feet away you will see as bigger

  • because your brain will say, "Well, if it takes up just this

  • much space but it's further away, it must be bigger than

  • something that's closer and takes up that much space."

  • And that's what goes on here. For the top line,

  • for the Mueller-Lyer illusion, we assume that this is further

  • away and this is closer based on the cues to distance.

  • And the cue is factored in. And because we assume that this

  • is further away, we assume it must be bigger to

  • take up the same space as this which is closer.

  • Similarly for the Ponzo illusion.

  • There's linear perspective. Parallel lines tend to recede

  • in distance. If this top one is further away

  • than this but they take up the same size in your eye,

  • this one must be bigger and you see it as bigger.

  • And the book offers more details on how these illusions

  • work. I'm going to end with an

  • illusion that I'm not even going to bother explaining.

  • I'll just show it to you because you should be able to,

  • based on thinking about these other illusions,

  • figure it out. It was developed by Roger

  • Shepard. Well, you know that.

  • And they are called Shepard tables .

  • And the thing about it is, these look like two tables.

  • If you ask people--You don't frame in terms of here's a

  • lecture on visual perception. You ask people,

  • "Which of these tables would be easier to get through a door if

  • you have a thin door?" People would say the one on the

  • left. This one looks sort of thicker

  • and harder to get through. This one looks longer and

  • leaner. In fact, they're the same size.

  • What I mean by that is that this is exactly the same as this

  • . Now, I'm going to prove it to

  • you by showing you something which took me--on the computer

  • which took me about seven hours to do.

  • And nobody's going to believe it because I could have faked

  • it. But if you want,

  • print it out and do it yourself.

  • You just take a piece of paper, put it on here.

  • Then you move it and the same. I showed it to somebody and

  • they called me a liar. Anyway, you could do it

  • yourself in the privacy of your own home or study.

  • But what I'd really like you to do after you do it is say,

  • "Okay. Fine.

  • Why does this one look longer and thinner than this one?"

  • And the answer is the same answer that will explain the

  • Mueller-Lyer illusion and the Ponzo illusion,

  • having to do with cues to depth and the way your mind corrects

  • the perception of depth. And that's all I have to say at

  • this point about perception. I want to move now to attention

  • and memory and I'm going to treat attention and memory

  • together. We are fascinated with memory

  • and, in particular, it's particularly interesting

  • when memory goes wrong. It's particularly fascinating

  • what happens in cases of amnesia.

  • So for example, I need a volunteer who is

  • willing to do a little bit of acting, a very little bit,

  • an incredibly little bit. Excellent.

  • Okay. So well, you just stay there.

  • So pretend you have amnesia. Okay?

  • What's your name? Student: I don't know.

  • Professor Paul Bloom: Perfect.

  • I'm really glad you said that. That's the wrong answer because

  • you don't have total amnesia. You still remember English.

  • Okay. It's very clever.

  • Okay. So you couldn't have lost all

  • your memories. You have English.

  • You --So we'll do you. What's your name?

  • Oh. He looks puzzled but he still

  • maintains bowel and bladder control so he hasn't forgotten

  • everything. [laughter]

  • Now, I always lose the third volunteer in that demo.

  • So, what I'm saying is that memory is a hugely broad

  • concept. It includes autobiographical

  • memory, which is what we standardly think.

  • That's a perfectly rational response.

  • When I say somebody's losing their memory,

  • "Oh. I have a movie about somebody

  • losing their memory," you don't imagine a person in diapers.

  • You imagine the person walking around, having sex with cool

  • people and saying, "Where am I?"

  • And [laughter] so what you imagine is you

  • imagine them losing their autobiographical memory,

  • their sense of self. But of course,

  • knowing English is part of your memory and knowing how to stand

  • and knowing how to chew and swallow are all things that

  • you've learned, that you've--that have been

  • molded by experience. There's another distinction

  • which is going to come in regarding amnesia,

  • which is there's broadly two types of amnesia.

  • They often run together, but one type of amnesia is you

  • lose your memory of the past. Another type of amnesia--That's

  • the Matt Damon amnesia. Another type of amnesia though

  • is you lose the ability to form new memories.

  • And here's a film of a man who had exactly this problem.

  • He was a world-renowned choir director and he suffered viral

  • encephalitis which led to brain damage which destroyed most of

  • his temporal lobes, his hippocampus,

  • and a lot of his left frontal lobe.

  • It could be--It could have been worse in that he retains the

  • ability to talk. He seems to be--He's not

  • intellectually impaired. He just can't form new memories

  • and so he lives in this perpetual "now" where just

  • nothing affects him and he feels--This has not always

  • happened. There's more than one of these

  • cases and it doesn't always happen like this,

  • but he feels continually reborn at every moment.

  • And we'll return to this and then ask what's going on here.

  • But there's a few themes here. I want to, before getting into

  • detail about memory, I want to review some basic

  • distinctions in memory when we talk about memory.

  • So crudely, you could make a distinction between sensory

  • memory, short-term memory, which is also known as working

  • memory, and long-term memory. Sensory memory is a residue in

  • your senses. There's a flash of lightning.

  • You might see an afterimage. That afterimage is your sensory

  • memory. There's somewhat of a longer

  • echoic memory for sounds. So as somebody is talking to

  • you even if you're not paying attention you'll store a few

  • seconds of what they're saying, which is sometimes,

  • when somebody's talking to you and you're not listening to them

  • and they say, "You're not listening to me."

  • And you say, "No. You were talking about--" and

  • pick up the last couple of seconds from echoic memory.

  • There's short-term memory. Anybody remember what I just

  • said? If you did, that's short-term

  • memory--spans for a few minutes. And then there's long-term

  • memory. Anybody know who Elvis is?

  • Do you know your name? Do you know where you live?

  • Your long-term memory store that you walk around with and

  • you're not going to lose right away.

  • When we think about amnesia in the movie sense,

  • we think of a certain loss of long-term memory associated with

  • autobiographical personal events.

  • There is a distinction between implicit and explicit,

  • which we'll talk about it in more detail.

  • But explicit, crudely, is what you have

  • conscious access to. So, what you had for dinner

  • last night. You could think back and say,

  • "I had this for dinner last night."

  • Implicit is more unconscious.

  • What the word--what certain word--what the word "had" means,

  • how to walk, how to ride a bicycle,

  • that you might not be able to articulate and might not even be

  • conscious of but still have access to.

  • There's a distinction between semantic memory and episodic

  • memory. Semantic memory is basically

  • facts, what a word means, what's the capital of Canada,

  • and so on. Episodic is autobiography,

  • is what happened to you. That Yale is in New Haven is

  • semantic. That you went on vacation away

  • from New Haven last week, it would be episodic.

  • There is encoding stores and retrieval, which refers to

  • different levels of what happens in memory.

  • Encoding is getting the memory in, as when you study for a test

  • or you have an experience. And storage is holding the

  • memory. And retrieval is getting the

  • memory out. Finally, retrieval is often

  • broken, conveniently, into recall versus recognition,

  • where recall is when you just pull it out of memory and

  • recognition is when you recognize what corresponds to

  • something in the past. Anybody remember what color tie

  • I had on two days ago? Oh.

  • Okay. Well, that would be impossible

  • to remember but if I asked you, "Is it purple or is it orange?"

  • that would be much easier. [laughter]

  • Now, you could break up, crudely, the memory into

  • stages. So you start that sensory

  • memory is just the stuff that comes in leading to short-term

  • memory, leading to long-term memory.

  • And this stage theory is something which we'll discuss in

  • more detail. But this leads us to the issue

  • of attention. How do you get memory from your

  • sensations, from what you're hearing?

  • I'm speaking to you. You're hearing me.

  • How does it ever get in to the other systems?

  • What decides what's remembered and what's not?

  • There's all sorts of things happening to you now.

  • The seat of your chair is pressing against your butt.

  • You wouldn't say, "Oh. I want to remember this forever.

  • The seat's pressing against my butt."

  • [laughter] Your neighbor is exuding a

  • certain sort of smell. You're thinking about something.

  • Your eyes follow him. Not everything gets in memory.

  • You'd go mad if you tried to remember everything.

  • You can't. So, what determines what gets

  • into memory? Well, one answer is "attention

  • does." And attention is--could be

  • crudely viewed as a flashlight, a spotlight on experience that

  • willingly zooms in on something and makes it memorable.

  • Attention has certain properties.

  • Some things come from attention--to attention

  • effortlessly and automatically. Here's an example.

  • You're going to see an array of letters here.

  • One of them's going to be green. When you see the green one,

  • please clap. [laughter]

  • No, not this green one. [laughter]

  • There's going to be another slide.

  • Okay. You're ready now.

  • but there's going to be an "o." When you see it clap.

  • Okay. Sometimes it's work.

  • Find the red "o." [laughter] It's harder.

  • Sometimes attention is involuntary.

  • I need a volunteer. And all I want to do is I want

  • to show you colors on the screen and I'd like you to name the

  • colors as they come out.

  • Do you want this? Student 1: I'm

  • colorblind. Professor Paul Bloom: Oh.

  • [laughter] The first one is easy.

  • See. This is--You have to just go

  • down the colors . Anybody?

  • Okay. Student 2: Red,

  • green, blue, black, green,

  • blue, red, blue, black, red.

  • Professor Paul Bloom: Excellent.

  • [applause] Okay. Now these.

  • These will be words but just name--Okay, you.

  • Just name the colors. Student 3: Green,

  • red, blue, black, blue, red, green,

  • black, red, blue. Professor Paul Bloom:

  • Perfect. Now, we'll go back to you,

  • same deal, words. Student 4: Red,

  • blue, green -- Professor Paul Bloom: No,

  • no, no. Huh uh.

  • Don't--I know you can read. The colors.

  • Student 4: Okay. Sorry.

  • Okay. Blue, green,

  • red, green, black, green, blue,

  • black, red, Professor Paul Bloom: Very good actually.

  • [laughter] That's known as the Stroop

  • effect. Being an expert reader,

  • as you are, your knowledge of reading, your attention to what

  • the words meant, subverted your desire to do the

  • task. You couldn't make that go away

  • even if you wanted to. If somebody gave you $1,000 to

  • read this as fast as you read this, and as fast as you read

  • this, you'd be unable to. You can't block it.

  • There is some work--There are some interesting discoveries

  • about attention. I have a demonstration here.

  • I'd like people actually--It's important--Some of you may have

  • seen this before. It's important for you to be

  • silent throughout it. What you're going to see is

  • you're going to see two teams of basketball players.

  • One of them is going to have white T-shirts.

  • The other one will have black T-shirts.

  • They'll be passing balls back and forth.

  • What I'd like you to do is count in your head how many

  • passes the white team does with the ball.

  • [laughter] What number did people get?

  • Okay. Did anybody notice anything

  • unusual? [laughter]

  • Did anybody not notice anything unusual?

  • Okay. Some people did not notice

  • anything unusual. Those who didn't see anything

  • unusual, watch this again and just watch it.

  • [laughter] About 50% of people when

  • counting, who have never seen this before don't notice

  • anything. But then when you're not

  • counting it's kind of obvious what you're missing.

  • [laughter] And this is one demonstration

  • among many of the fact that when you're attending to something

  • you have a very small window of attention and you lose the focus

  • on other things. Here's another different

  • example. I'd like people to watch a

  • movie and pay attention very closely to what happens in the

  • movie and try to remember this. How many of you noticed

  • something odd in that movie? How many of you didn't?

  • Okay. Now, everybody look at the

  • scarf, the color of the plates and the food,

  • among other things. The phenomena,

  • in general, has been called "change blindness."

  • And what it is is we tend to be--when there's a focus of

  • attention focused in a certain way,

  • we tend to be oblivious to other things that go on in the

  • environment. Often it is,

  • in fact, quite difficult when there's a change in scene to

  • notice what changes and what stays the same.

  • So, in this final demo, there's just going to be two

  • pictures flicking. Could you clap when you see

  • what's different between the two pictures?

  • [applause] [laughter]

  • I myself am terrible at these and so I have a lot of sympathy.

  • How many people never saw it?

  • [laughter] Good. That's very impressive.

  • [laughter] One more time with a different

  • one.

  • [applause] Did anybody not see it?

  • Be honest. I'll give you another try.

  • [applause] Okay. I'll put you out of your misery.

  • [laughter] This is work by Dan Simons and

  • it's part of an extraordinarily interesting body of work on

  • what's known as "change blindness."

  • And what this means is, the phenomena is,

  • we have a very narrow focus of attention and huge changes can

  • happen that we are oblivious to. This is why,

  • in movies, there are so many--so much difficulty with

  • continuity changes. Dan Simons is also famous for

  • having brought this outside of the laboratory in some classic

  • experiments and I'm trying to get the film corresponding to

  • them. What he did was that he did

  • this great study in the Cornell campus where he was--where what

  • happened is they would get some unsuspecting person walking

  • through campus and some guy would come over and say,

  • "Excuse me, Sir. I'm lost.

  • Could you help me with directions?"

  • And have a map and then the person would say,

  • "Sure." And then there'd be two

  • construction workers holding a door.

  • And these guys were going to rudely bump between these two

  • characters and then the experimenter gets switched with

  • another guy. So now, when these two guys

  • walk away, the subject is standing there with an entirely

  • different person. [laughter]

  • What's interesting is nobody notices.

  • [laughter] They notice if the person

  • changes sexes. "Didn't you used to be a woman?"

  • [laughter] And they notice if the

  • experimenter changes races, but most other changes they're

  • oblivious to. There's another experiment.

  • I think Brian Scholl did this one but it may have been Dan

  • Simons where what happens is a subject comes in to the lab.

  • They say, "If you're going to do an experiment with us,

  • you need to sign the human subject form."

  • Hands him the form, the experimenter.

  • The subject signs the form. The experimenter takes the form

  • and says, "Thank you. I'll put it down here."

  • Goes down here and then a different person pops up.

  • [laughter] People don't notice. And there's a certain level on

  • which we're oblivious to changes.

  • What's weird is we don't see--we don't think we are.

  • We think we see the world as it is and we don't know--notice

  • that when we're attending to something;

  • everything else gets blanked out.

  • And so about 50% of people who have never seen this demo

  • before, the gorilla demo, they don't notice the gorilla.

  • And there's--you couldn't imagine anything more obvious.

  • The gorilla study was actually done a very long time ago.

  • And it was originally done in a different way but I'll show it

  • to you just because this is the original study and now that you

  • all know what to expect--Oh, not that one.

  • Oops. Nope.

  • That's actually--If you looked at that quickly,

  • it's a current Yale professor. Oh.

  • I'm never going to get my DVD back.

  • Anyway, I'll show you the other demo on--next week.

  • I will. [laughter]

  • Any questions about attention and memory at this point?

  • Yeah. Student: [inaudible]

  • Professor Paul Bloom: Yeah.

  • Why does it work that way? Why is it--Why do things that

  • become very practiced become automatic and involuntary?

  • It's a good question. I don't know.

  • We know that they do. We know that once you--that you

  • can't not read once you know how to read.

  • You also can't not listen. If I'm talking to you and I'm

  • extremely boring, but I'm talking to you,

  • it's very hard not to listen. You can't shut off your ears.

  • You could put your fingers in them but you can't shut off

  • your--You also can't shut your eyes without actually shutting

  • them. You can't say,

  • "This is a disgusting movie. I'm not going to attend to it."

  • [laughter] So, that's not answering your

  • question. It's just saying that your

  • observation is a right one and a more general one.

  • When you're good at something and you're over-practiced,

  • it becomes involuntary and you cannot stop it.

  • Okay. Well--Oh.

  • One more in back. Yes.

  • Student: [inaudible] Professor Paul Bloom:

  • What now? Sorry.

  • Over there. Yeah.

  • Student: [inaudible] right before his accident?

  • Professor Paul Bloom: Did he remember things before

  • his accident? Yes.

  • He had some amnesia of events before his accident but he did

  • remember things. He knew his name and he knew

  • other things about his life. Okay.

  • I'll see you next week.

Professor Paul Bloom: Two follow-ups on

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7.意識到現在;意識到過去。語言 (7. Conscious of the Present; Conscious of the Past: Language)

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