8.現在を意識すること、過去を意識すること。 (8. Conscious of the Present; Conscious of the Past:)

字幕表動画を再生する

Professor Paul Bloom: I'll begin the class officially
with a different sort of demonstration.
I want to just show you one of the change-blindness studies
that has been done in the real world.
And these videotapes are not available publicly.
We get them from the web and see them as little Java scripts.
So, this is one of the first studies done by Dan Simons when
he was at Cornell. And his adviser at the time was
our Frank Keil, who's now in our department.
So, here's the study.
[laughter] And you don't notice it.
Change blindness is one of the more striking phenomena
discovered by laboratory scientists and by psychologists.
But it's important to realize, to get away from the sort of
surprise of the gorilla and the fact that it's hard to see the
flickering--the object that's flickering,
and appreciate the big moral of this, because the big moral of
this is actually, I think, striking and quite
important. You think right now that you're
perceiving the world. I look down on you and I think
I have a whole sense of where everybody is.
I can't see everybody perfectly in back.
You're kind of far away and blurry but there's a sense in
which I have a world around me. Similarly, if I'm to close my
eyes for a second, everything just remains and I
could sort of remember some of the things that are there.
That's really good sound localization by me .
So you're looking up and you think you have a sense of the
world both in perception and memory.
The change-blindness experiment suggested this isn't true.
The change-blindness experiment suggests that if you look at me
for a second and during that second all of your classmates
change positions, including those next to you,
you are extremely unlikely to notice.
The change-blindness experiment suggests that if you turn your
eyes away from me towards there for a second and turn back,
and I'm dressed entirely differently, you wouldn't
notice. The exceptions would be if you
told yourself consciously, "Remember what this guy is
wearing; he's wearing this,
that and the other." But if you don't do it
consciously you'll lose it, and usually this is okay.
Usually, it's okay because your memory and your visual system
exploits a basic fact about the universe,
which is that most things stay the same most of the time.
I don't have to explicitly remember that you're over there
when I turn my head for a second because you'll be over there in
any case. You don't need to hold precise
representations of the world. And so you only notice it in
certain clever circumstances. One sort of clever circumstance
is when psychologists change reality as in the
change-blindness studies. A second sort of circumstance
is in movies. So, one of the big surprises
when people started making movies involving cuts was it is
extremely difficult to get everything continuously right.
And you need to work very hard to notice.
So, there's all of these continuity errors that creep up
into movies and you have to be a film buff or writing it down to
even notice this. And the overall moral here then
is that your perception of reality is a lot more sparse,
a lot more limited, than you might think it is.
So, this is where we were at the end of last class.
We were talking about the different sorts of memories:
Sensory memory, which is the sort of fraction
of a second of sensory residue of what you're hearing and what
you're seeing, working memory,
short-term memory, and then long-term memory.
And we talked last class about how things get into sensory
memory, into working memory, the role of attention.
And in fact, the change-blindness studies
are actually just studies of how something gets from your senses
to your consciousness and what does and what doesn't.
Now I want to move to the distinction between working
memory, short-term memory, and long-term memory.
Now, the obvious distinction is actually just in fact--is
storage differences. So, long-term memory or "LTM"
has a huge storage capacity. This is your memory like the
hard drive of your computer. This is the memory you walk
around with. It includes all the words in
English, just for example, 60 to 80,000 words.
It includes everybody you've ever met, languages,
faces, stories, locations, nursery rhymes,
songs, TV programs. Nobody knows the storage.
It is not true that you remember everything that has
ever happened to you. There's no reason to believe
that this is true. At the same time though,
you have a huge amount stored in your brain in long-term
storage and nobody actually--It has to be limited because it's a
finite, limited brain.
But nobody knows how big it is. Nobody knows how many terabytes
you carry around in your brain and--but it's a lot.
Compare this to working memory – the short-term memory,
which is actually very limited. Your memory of what you could
store on--in--where you could hold in consciousness right now
is quite limited. Here is an exercise.
Do not write these things down. I want you to remember them.
I'm just going to give you a few numbers: 14,59,
11,109, 43,58, 98,487, 25,389,
54. Please write them down.
View this as an IQ test if that would relax you.
How many of you who decided to participate in this experiment
got three or less? Good.
Good. Four, five, six,
seven, eight, nine or more?
Anybody get all eleven? This is a particularly
difficult memory task. The numbers are meaningless.
And I told--and I forgot to tell you to get your pen and
pencil ready, so some of you just glared at
me. But [laughter]
under normal circumstances the cognitive psychologist George
Miller said that this sort of suggested that the standard
memory storage of short-term memory is seven,
plus or minus two. And what that means is anywhere
from five to nine roughly. Some of you,
I bet, can beat that. Some of you on a not-so-good
day maybe won't make it that much.
Now "seven plus or minus two" is what you--;so,
that's what you hold in consciousness.
I can tell you 14,21. You walk around,
"Oh, yeah, 14,21." You hold that in consciousness
with no problem. But I throw eleven numbers at
you, you can't. Some dribble out.
You can't hold that in your conscious window in your
short-term memory. Now, this raises the question
"seven plus or minus two" what? And the answer seems to be what
George Miller calls "chunks." And a chunk is a basic memory
unit, something you think of as a single, individual entity.
So, suppose you see the string of letters "L,
A, M, A, I, S, O, N."
If you don't know--If you can't form these into words and you
have to remember them, these are eight chunks.
You have to just pick them up separately.
On the other hand, if you break them up into four
words you could just remember it as four chunks.
And if you break it up into two words in French,
"la maison," "the house," it could just be one or two.
How much you know depends--affects how much you
memorize--how much you could store in memory because it
affects what counts as a basic unit of memory.
And there's all sorts of examples of this.
If I tell you "1,1, 0,1, 1,0, 0,1,
0,1, 1,0," those of you who don't know binary numbers might
have to remember that as "1, 1,0, 0," whatever I said.
Those of you who are computer scientists or mathematicians or,
for whatever reason, know binary numbers could
convert it into a single binary number.
Anybody know what the number is? No, I cannot say it again.
[laughter] Some number,
24, or not 24--to some number, 24, and then you remember "24."
It's easier. Suppose you see a chessboard
and the chessboard is set up and you don't know how to play
chess. It is murderously hard to
remember that. They've done the experiments.
They've taken people in a lab who don't know how to play
chess. They set up a chessboard and
then they say, "Okay.
Look at this for five minutes." Then they take it away,
set it up again, and it's murderously hard.
"There is a horse-y thing on the side there and everything."
But if these chess pieces are set up in some way that's
logical for a chess player, then a chess master could look
at it and remember it in a glance, "Oh.
It's the Fibonacci defense" or something like that [laughs],
and then immediately recover it.
Similarly, football coaches have been tested on their
memories of football diagrams. And they have a photographic
memory for football diagrams because it corresponds to things
that make sense. Architects could have a
photographic memory, a perfect memory for floor
plans because it makes sense to them.
They understand it. And so the way you store things
in memory, and this is a theme we're going to return to when we
get to long-term memory, depends in a large extent on
how much you understand it. And this shows up in expertise
effects. Now, this is what's happening
so far in short-term memory, how much you hold in there.
The question is how do you get it into long-term memory?
So, you have long-term memory, your major storage system.
How does information get from your consciousness to long-term
storage? Well, there's one
thing--there's one way which sort of works sometimes but not
very well. And it's called "maintenance
rehearsal." Suppose I said you have to
remember this number, this string of numbers.
And if you remember it in twenty minutes you will get one
thousand dollars. And the string is my phone
number when I was a kid. I'll include the area code:
514-688-9057. Now, if you tell that to a
four-year-old, well, the four-year-old will
say, "I'll remember it." And then you ask them,
"What did I just say?" "Well, I don't know."
If you tell it to an--because you know something--If a lot
depended on it, you would know to do something.
What you would do is you'd say to yourself, "514-688-9057,51
4-688-9057,514-688 --" You'd rehearse it in your head over
and over again. The problem is you could hold
it as long as you can do that. It's like these movies.
You see this all the time, like an episode of 24:
"Jack, call CTU and tell them Agent 11 is trapped in a--" And
I can't even remember this but the way to remember it is you
hold--you've just got to repeat it over and over again in your
head. But this will not typically get
things into long-term memory. To get things into long-term
memory, rehearsal is usually not enough.
You need to do other things. Typically, what you need is
structure and organization. And one way to demonstrate this
was in a classic "depth of processing" experiment which
nicely illustrates the fact that the more you structure
something, the deeper you think about it,
the better it gets entrenched in the long-term memory.
So, in this study what they did was they asked people--they told
people that there's going to be words flashed on a screen.
And all of the subjects saw the same strings of words.
There were forty-eight words. They were not told to memorize
the words. One third of the subjects was
told, "Look. Some of these words are going
to come out in capital letters, some of them not capital
letters. Press a button for capitals,
non-capitals." "Sure."
The other group was told, "Some of these words will rhyme
with 'train,' Others won't. Press a button if it rhymes in
'train'." The third group was told,
"Does it fit into the sentence ‘The girl placed the blank on
the table'? Press a button if it does.
Press a button if it doesn't." Then they were asked as a
surprise, "What words did you see?"
And the findings looked like this.
When they were asked to focus on just what the word looked
like, memory was very poor, the sound better,
the meaning better. If you want to remember
something, the best way to remember it is to give it
meaning, to give it sense. This is illustrated through a
very ancient technique, which is that the way to
remember things that are otherwise arbitrary is to give
them some organization through memory tricks,
through vivid imagery or songs or poetry.
And there's a lot of examples of this.
Do you know how to remember that the hippocampus--There's a
part of the brain called the hippocampus.
This is the worst memory trick ever but it will stick with you
for twenty years. The hippocampus is involved in
spatial memory. It's involved in finding your
way around. Think to yourself,
"The way I find my way around campus is through the
hippocampus." And you think,
"Well, that's stupid," but you'll never forget now that the
hippocampus is in charge of spatial memory.
It's going to be all you retain from this course.
Memory books on how to remember people's names usually try to
exploit this sort of thing when you try to get poetry or
dramatic images. So, the memory books always
typically involve somebody--like you meet somebody with very
spiky hair and they say, "My name is Mr.
Fish" and then you remember--you think of their--of
a big fish impaled on their hair.
And then whenever you see them you remember their name.
It only really works for names like "Fish" but [laughter]
the idea is you try to generate vivid imagery.
When stuck with a situation where you have to remember ten
letters, turn it into a song where--or a dirty poem where
each of the letters is the first words of it.
When having to remember something that seems totally
arbitrary, try to figure out a grand and obscene image that
will come to mind easily. And this is how--these are one
way to get things into memory. At a deep level though,
the way to get things into memory, and this applies to this
course no less than anything else,
is by understanding the--understanding it.
I'm going to read you something and I want you to try your best
to remember what I tell you. These are not going to be
strings of numbers. These are going to be--This is
going to be a series of sentences: "A newspaper is
better than a magazine. A seashore is a better place
than the street. At first it is better to run
than to walk. You may have to try several
times. It takes some skill but it's
easy to learn. Even young children can enjoy
it. Once successful,
complications are minimal. Birds seldom get too close.
Rain, however, soaks in very fast.
Too many people doing the same things can also cause problems.
One needs lots of room. If there are no complications,
it can be very peaceful. Finally, a rock will serve as
an anchor. If things break loose from it,
however, you will not have a second chance."
And here is what I said . This is murderously hard to
remember. Now try it.
Knowing what this is about, being able to put a context to
it helps the memory and helps it come to mind.
[laughter] Okay. So, this is about how to get
memory--how to get information into your memory.
How do you get information out? So, it's exam period.
You got the stuff presumably into your head.
You have to get it out. You have to retrieve it.
There is a court case. You have to figure out--You
have to recount the crime that you witnessed.
You see somebody and you want to know his or her name.
And you heard it; you just have to get it out.
Well, how do you do that? Well, there's "retrieval cues."
Retrieval cues make sense. Retrieval cues are just things
that have been associated with what you--what you're trying to
remember. If I have to remember to
replace the windows, when I walk in to my living
room and see that a window is cracked that will remind me to
replace the windows. If I had a lunch date with you
and forgot about it, when I see you,
"Oh, yeah. We were supposed to get
together to have lunch." Retrieval cues bring things
back but it's a little bit more complicated than that.
There's a more general relationship between encoding
and retrieval called the "compatibility principle."
And what this means is you're much better to remember
something in the context in which you have learned it.
And this is also known as "context-dependent memory" and
"state-dependent memory." It's illustrated by one of the
strangest experiments in the history of psychology where they
had people on a boat and then they had them scuba dive
underwater. And they taught them things
either on the boat or underwater with things that they held up.
And then they tested them later. And it turns out that you'll
remember it better if you're tested on it in the context in
which you learned it. And it might be because then
the retrieval cues help bring it back.
But it's more general than that. If you have to remember
something you learned in this class, you will do better if you
try to think about the room in which you learned it in.
You will do better on your final exam if you were to take
it in this room than if you were to take it in another room
because being in this room will bring back the cues.
It's not just the environment. People who learn things when
they're stoned remember them better--keeping stoned at a sort
of a low-level that doesn't disrupt other mental
activities--remember them better when they're sort of stoned
again [laughter] than if they're non-stoned.
Similarly--So, if you study while you drink
you should tipple a little bit before coming in to the Final
exam. [laughter]
It's sort of like the "what happens in Vegas stays in Vegas"
sort of result. And so, similarly,
it even applies to moods in that if you learn something when
depressed you have a slightly better recovery of it when
you're in that same mood of depression than when you're
elated. And the idea is that part of
what memory is--part of what recovering memory is is getting
back your original context in which you learned it.
"Elaborative rehearsal" and retrieval involves the
connections between different things.
Elaborative rehearsal is that the more you think about
something the easier it is to remember.
If you have to think about--If you have to remember something,
try to connect it to as many things as possible.
Think of an image. Make a joke out of it.
Imagine how you would explain it to somebody else.
Imagine how the world--what the world would be like if it wasn't
so. And the idea is that this sort
of thinking about it makes connections in your memory from
that thing you have to learn, to other memories.
And so it makes it easier to recover.
"Elaborative retrieval" refers to a finding that when you want
to get something back out of memory people tend to give up
too soon. It turns out that there's a lot
of stuff that's in your memory but it needs work to extract;
it needs various sort of searching strategies.
One study asked people who were considerably older than you to
remember their high school classmates.
And in the first pass people were terrible.
Maybe they had a couple of friends they kept in touch with.
Otherwise, pretty bad. And this is a good experiment
because you could use high school yearbooks to judge
whether or not they get it right.
But then what you do is you tell the person,
"Look. Keep trying.
Were you--What sort of--Who was your teacher?
What sort of clubs did you belong to?
What sort of sports you--did you participate in?
How did you get to school? How did you get from school?
What did you do during lunch? What did you do during break?"
And you keep ask--"Do you know--have any friends whose
letter--whose last name began with ‘B,' with ‘C,' with
‘D'?" And you keep pushing and
pushing and pushing. And over the span of time
things come back. Again, it's not true that you
never forget. There is honest to God
forgetting but sometimes you think you forget and it's
because you haven't looked long enough.
There's a real physical notion of searching for the right
answer. We've talked about retrieval.
Oh. Every class I've given somebody
asks either in class or by e-mail what about déjà vu?
And déjà vu is a feeling that an event has happened before.
So, you're looking at me and I'm lecturing and you say,
"I've heard this before. I know this before."
You see somebody and say, "I've been in this situation
before." This is not evidence for
psychic powers, [laughter]
which many people say it is, but nobody really knows why
this exists. We know, and this is a clue,
it's worse with frontal lobe damage.
If you get damage to this part of the brain,
you get a lot more déjà vu experiences.
I asked some experts in memory, including Marcia Johnson who is
chair of our department, what the best explanation for
déjà vu is. And the answer she gave,
the--say one big theory, goes like this.
Déjà vu is a feeling that it's happened before.
The answer is it has happened before.
It's happened half a second ago. And so what happens is
sometimes there is a glitch, a disturbance in the force.
I don't know. There's a glitch [laughter]
and you are talking and then something happens to you and you
put it in your memory. But it's as if you don't put
the stamp on it of what time and what date.
So, you're talking to me and then you store it in memory but
you don't store it in memory as happening right now.
Then half a second goes by and you're talking to me and you
say, "This is strangely familiar."
And that's one theory of what goes on in déjà vu.
Okay. So far, there's the sort of
good news – remembering – but then there's bad news –
forgetting. How many people can remember,
without looking down at your notes, at least two of the
numbers I gave you earlier?
How many people can remember at least four?
Oh, impressive. If I asked you in an hour,
the number would go down. These are sort of statistics in
a similar experiment. And this graph illustrates that
people forget. Over time, you'll forget.
Why do you forget? Why is there forgetting at all?
Well, there's different explanations for this.
One explanation is your brain's a physical thing,
it's a physical piece of meat, and it kind of goes bad.
Physical things decay. And so, the memory traces that
are laid onto your brain will just decay over time.
A second answer is interference. So, remember those numbers?
Here's a few more: 114,81, 66,42.
Well, the more information that comes in that's similar to the
stuff you're trying to remember, it blocks your recovery of
original information. So your ability to remember
something can be impaired by learning more things which are
related to it because they get confused in memory.
Finally, and maybe this is most interesting, there are changes
in retrieval cues. So, the more time goes by the
more the world changes. And if your memory is to some
extent dependent on cues bringing it back to life,
then the change in retrieval cues can make it more difficult
to recall certain things. This leads to a puzzle where
there's considerable scientific debate over the case of
childhood amnesia. And the case of childhood
amnesia is--doesn't refer to when a child gets brain damage
and gets amnesia. What it refers to is people
have a difficult time recovering very early memories.
I want people to just take a second and try to think back on
what your first memory is and roughly how old you were.
How many people don't think you have a first memory until you
were about five years old or older?
Okay. How many people think you have
the first memory of around age four or younger?
How many people think you have the first memory of around age
three or younger? Two or younger?
How many of you think you have the first memory when you were
about one years old or younger? And I'm not asking about past
lives but that [laughs] happened last year.
How old is your--roughly your first memory do you think?
How old? Student:
Between one and two. Professor Paul Bloom:
Between one and two? Anybody think they could beat
that? Same guy?
Yeah. Student: One.
Professor Paul Bloom: One.
[laughter] Anybody else? The literature is unclear on
this because it's very difficult to test people's recollections
of their first memories. If I'm to ask people about
their first memories, they'll often say,
"Oh, yeah. I remember I was in this room
and there was a crib and I'm going ‘Ga ga,
goo goo' [laughter] and I was on the potty.
I was walking. I was so cute.
I remember it." It's very difficult to tell
and, as we'll discuss in some detail, there are a lot of
reasons to distrust people when they--not that they're lying but
to distrust the accuracy of people's memories.
We also know from studies about trauma where people have
terrible experiences when they're one or two.
Typically, this trauma is not remembered later on.
People know of trauma because they're told about it but they
don't typically remember it with any accuracy.
Even children--older children don't remember back beyond that
age. Nobody knows why childhood
amnesia occurs. Nobody knows why it's very
difficult to recover memories before about the age of three.
One theory is that the retrieval cues change radically.
I had a friend of mine who's a clinical psychologist and he
suggested a new form of therapy where they make these giant
tables and chairs and then they bring you in to the office and
you're standing there with these giant tables and chairs
[laughter] and all these memories of being
a baby would come flooding back. [laughter]
And he dropped out of the field and-- [laughter]
Really, but it's such a cool idea.
Some people think language is to blame.
So a child, a baby, starts out with no spoken or
signed language. Language comes to be learned at
around one, two, and three, and it might be that
the learning of a language reformats your memory.
And once the memory is reformatted it can't go back to
the previous state prior to language in the end.
It could be neural maturation. It could be that those memory
parts of the brains grow around age two or three that just
weren't there prior to that. And nobody really knows.
It's a fascinating research area why--about memory changes
early on. Another case of memory failure
is brain damage. And brain damage comes in a
couple of flavors. There is retrograde amnesia;
"retro" for past. Retrograde amnesia is when you
lose some memory of the past. This could be in a case where
you get some sort of head trauma and you lose memory of your
entire episodic memory. But typically,
if you have any sort of serious accident that involves you
losing consciousness you'll have a blackout of some period prior
to that, say, blow to the head.
And the reason for this is as you're having these experiences
now they need to kind of get consolidated into your brain.
Your brain needs to rewire and catch up to the experiences
you're having. A sudden blow to the head will
knock you unconscious and then the memories that have happened
immediately prior will not get consolidated and they'll be lost
forever. Another sort of memory is
anterograde amnesia and this was the case of--This happens in
Korsakoff's syndrome. It happens to a very famous
patient known as H.M. who actually lives in Hartford,
Connecticut. And it happened to Clive
Wearing, the film you saw last class.
And this sort of amnesia is a sort of amnesia where you lose
the ability to form new memories.
And so you live in a perpetual present, unable to accumulate
new memories. But it's actually a little bit
more complicated than that. What happens is--And this was
an exciting discovery about these patients that led to some
real insights about normal memory--What happens is--And
this is the brain damage in these cases,
the temporal lobe and the hippocampus, very useful for
spatial memory you'll know. One discovery made about people
who couldn't form new memories is that they could form new
memories, but of certain types. So for example,
this is a task here involving filling in a star while looking
in to a mirror. And if I asked you to do it
you'd find it pretty difficult. It's just kind of difficult to
do. You'd be clumsy at it.
You bring in an amnesic who can't form new memories and you
say, "Hey. I want you to try something new.
I want you to try this star game."
He'd say, "Okay. I've never seen it before but
I'll do it." Tries it.
Does very badly. You bring him in and over and
over again--Each time he does it he starts off by saying,
"I've never seen this before. I'll--I'm sure I'll give it a
try" but he gets better and better at it.
And this is known as implicit memory.
The claim is that in these sorts of cases you lose the
abilities to form explicit conscious memories that you're
aware of, that you understand. But some sorts of memories
persist and you are able to form them.
This has actually been illustrated in a couple of
dramatic movies, one of them a very bad dramatic
movie [laughs] where Drew Barrymore loses the
ability to form new memories and somehow falls in love with Adam
Sandler. [laughs]
Definitely don't watch that. But a very good movie called
"Memento," which is about a character who loses his ability
to form new memories while trying to track down his wife's
killer. "Memento" is a movie which is
fascinating because it's told backwards.
But throughout "Memento" there's another story told
forwards. And I like this story because
it very dramatically illustrates what does, and what is and is
not impaired in cases of severe memory damage.
So, I'm going to show you a couple of clips that illustrate
the disassociation from "Memento."
Those of you who have seen the movie know that this ends up
quite tragically for Sammy. I highly recommend the movie.
We've dealt right now with two sorts of failures of memory.
One is everyday failure of memory when you forget.
How many of you remember three or more of the numbers I
originally presented? Yeah?
Go ahead. Student: [inaudible]
Professor Paul Bloom: Fourteen, 59,11.
Is that right? [laughs] Fine.
[laughter] All right. I'm going to ask you again in a
month. [laughter]
Well, people are supposed to forget [laughter]
and some things will--you will forget.
That's normal forgetting. A second case is forgetting due
to brain damage. Forgetting due to brain damage
is exotic and unusual but it's interesting in that it
illustrates some more general themes about how the mind works.
Remember one theme of this course is we're going to look at
exotic cases like the case of Clive Wearing,
not just because they're interesting in their own right
but sometimes by looking at the extremes we could learn
something about how normal people's normal,
intact minds and brains work. The third case of forgetting is
more interesting and it actually--Well,
I want to do a little trial here.
What I want to do is I want to--You to listen to three
children describe an event that happened.
I want you to come to some--your own guess.
Imagine you were a judge, you were a childcare worker,
you wanted to see--I want you to be--come to your own guess
about who you believe and what you think happened.
[inaudible] [laughter]
You've heard three children. Who do you believe?
Who believes--There's three of them, one, two,
three. Who believes the first one?
Who believes the second one? Who believes the third one?
Sort of an even split.
Twenty-three hundred experts were shown these films and asked
about the different actions, whether or not the person
ripped the book, messed up the bear,
tossed the book in the air and, as you could see,
the majority thought that he did.
This is work done by Steve Ceci who was gracious enough to lend
me the film to use for teaching purposes.
It turns out the second girl was right.
Absolutely nothing happened. [laughter]
The teacher said, "There is somebody named Sam
Stone who's going to come in." A guy walks in and says,
"Hi," walks around and leaves. [laughter]
The first and third children had their memories implanted,
not through any sort of science fiction means.
They had their memories implanted--Well,
they had their memories implanted like this.
Some of the children would just ask questions.
The interviewer, by the way, was herself unaware
of what happened so the interviewer was a perfectly
naive interviewer. And it turns out if you just
interview children and you ask them questions about whether the
book was ripped, "Did you see him?
Did he really do it?" they don't say anything.
They didn't see anything and they won't say anything.
Other children were told about Sam Stone.
They were told a stereotype about Sam Stone – that he's
very clumsy and he tends to rip things and he trips and he
breaks things and he spills things.
And in fact, the third child mentioned that
in passing. He said, "He always does that."
Just knowing this about Sam Stone tends to raise the
proportion of kids who say, for instance,
that he ripped the book. Other children were given
suggestions. They were given suggestive
questioning. They were a series of leading
questions like, "Oh.
Sam Stone came in? Did he rip a book while he was
there?" And still more children got
both. And in fact,
the children you saw were from this group.
They heard Sam Stone being described as a clumsy fellow and
they were given a series of suggestive questionings.
In this condition they were given several suggestive
questionings over the period of several months.
These children, like the first child and the
third child, are not lying. They honestly believe that Sam
Stone came in and did these things.
Also they believe it and they're so convincing in their
belief that experts, including police officers and
child caseworkers and judges and lawyers, find these children to
be extremely believable. And I think they probably find
them to be extremely believable because the children are not
lying. They really believe they saw
what they saw. But these memories were
implanted. And Ceci, and many other
investigators, study how memories can be
implanted in people's minds through suggestion and through
leading questions. It turns out that the same sort
of experiments and the same sort of research has been done with
considerable success in implanting false memories in
adults. There are dramatic cases of
people remembering terrible crimes and confessing to them
when actually, they didn't commit them.
And this is not because they are lying.
It's not even because they're, in some obvious sense,
deranged or schizophrenic or delusional.
Rather, they have persuaded themselves, or more often been
persuaded by others, that these things have actually
happened. Psychologists have studied in
the laboratory how one could do this, how one can implant
memories in other people. And some things are sort of
standard. Suppose I was to tell you a
story about a trip I took to the dentist or a visit I took to--or
a time when I ate out at a restaurant and I'm to omit
certain details. I omit the fact that I paid the
bill in a restaurant, let's say or I finished the
meal and then I went home. Still, you will tend to fill in
the blanks. You'll tend to fill in the
blanks with things you know. So, you might remember this
later saying, "Okay.
He told me he finished eating, paid the bill and left,"
because paying the bill is what you do in a restaurant.
This is benign enough. You fill in the blanks.
You also can integrate suppositions made by others.
And the clearest case of this is eyewitness testimony.
And the best research on this has been done by Elizabeth
Loftus who has done a series of studies,
some discussed in the textbook, showing how people's memories
can be swayed by leading questions.
And it can be extremely subtle. In one experiment,
the person was just asked in the course of a series of
questions--shown a scene where there's a car accident and asked
either, "Did you see a broken
headlight?" or "Did you see the broken
headlight?" The ‘the' presupposes that
there was a broken headlight and in fact, the people told--asked,
"Did you see the broken headlight?"
later on are more likely to remember one.
It creates an image and they fill it in.
In another study, she would show film segments
and then ask, "Did you see the children
getting on the school bus?" Now, there was no school bus
but people who hear that question later on when asked,
"Did you see a school bus in the film?"
are more likely to say yes. In another study,
she would show people film segments and ask them either,
"How fast were the cars going when they hit each other?"
or "How fast were the cars going when they smashed into
each other?" A week later she'd bring people
back in to the laboratory and ask, "Did you see any broken
glass?" Those who hear a smash tend to
see the broken glass more than those who hear a hit because the
question has changed their memory,
making it more of a dramatic event.
Hypnosis is the clearest case where there's a sort of
reconstructive effort led by--led as a result of leading
and probing questions. Some of you are readily
hypnotizable and you can be hypnotized.
And what we would learn about a past event from hypnotizing you
will not necessarily then be inaccurate.
What hypnotizing does is it makes people very willing to
cooperate. Unfortunately,
it isn't as if there is a memory storage there where you
could just go through and look as in the movies where you just
say, "What's the license plate?"
The person's hypnotized and then the flashback comes in and
then they zoom in on the license plate.
Memory doesn't work that way. What happens is--What somebody
will do in a hypnotizable state is they'll be very eager to
please the hypnotist. And so they'll make stuff up.
And people under hypnosis just make stuff up.
And they do very enthusiastically and very
believably make stuff up. This is particularly the case
with hypnotic regression when we ask you to go back to your sixth
birthday party, for instance.
And what's great as a developmental psychologist is if
I ask you to go back to your fourth birthday party and you're
hypnotizable you'll be oh, just like a four-year-old
except you won't be like a real four-year-old.
What you'll be like is an adult's notion of what a
four-year-old is supposed to be. In fact, this has happened in
the extreme case with hypnotic regression where people claim to
speak languages like from ancient Egypt.
And linguists love these studies because you don't--of
course you don't really sound like you're speaking a language
from ancient Egypt. What you sound is like a North
American who believes he's speaking a language from ancient
Egypt so they're, "nonsense sounds."
[laughter] And so what it makes you
is--Hypnotism brings out the actor in you.
It makes you want to give a persuasive account of what
happened. And so hypnotism is just an
extreme form of what normally happens in eyewitness testimony.
Repressed memories. We could devote a class--We
could devote a semester to the very heated debate in the United
States mostly about repressed memories.
There are many adults who have claimed to have experienced
traumatic sexual abuse. In some cases,
this is unexceptional from a memory point of view.
People know this happened to them.
They've always known it happens to them and then they tell
people about it. But there's a subset of cases
where people have had no memory up to a point of what happened
to them. Then they go to a psychologist
or a psychiatrist; they undergo questioning,
often using hypnotic techniques;
and then they recover a memory of past traumatic sexual abuse.
And what this is--what makes this so debatable,
and there is a debate about this.
I don't want to try to preclude it one way or another.
What makes this debatable is some psychologists believe that,
in at least some cases, these memories are real and
they have been repressed through a Freudian mechanism – that
they're too terrible to bring to consciousness,
and the therapy brings them out into real life.
But most psychologists believe that these memories cannot be
trusted, that these memories are created through the actions of
the therapist. And so, there's actually
considerable psychological and legal battles over the veracity
of the therapists where women who have claimed to have
sexual--be sexually abused, for instance,
have pressed criminal charges against their fathers on the
basis of false memories. Similarly, people who have been
accused of sexual abuse have pressed criminal charges against
psychiatrists claiming that these psychiatrists have
implanted the memories into their sons and daughters.
It is controversial whether memories are ever repressed.
What isn't controversial is that, for at least some cases,
you can implant false memories in people,
not because you're a sinister or evil person but because you
really believed something happened.
And you talked to them about it and then you caused these
memories to come into being. A final case is flashbulb
memories. I asked this early in the
semester. I'll ask it again.
How many of you remember where you were on September 11,2001?
Is there anybody who doesn't remember where they were on
September 11,2001? It would be interesting.
It was a socially relevant event, but here's the problem
with these flashbulb memories. Flashbulb memories are the idea
that these memories being so vivid, and they are vivid for
many of us--exactly where we stood, what happened;
well, they can't really be trusted.
And here is why not. Because they are such important
events, I bet many of you have actually heard the question
before, "Where were you on September 11^(th)?"
and talked about it. What happens in these
conversations is stories change. I have my--I knew where I was
on September 11^(th). My wife knew where she was.
But I spent as much time listening to her talk about it
as I spent time me talking about it.
And now maybe my memory is actually of her experience and
not mine. It's not--For all of these
cases, the temptation you have to resist is saying,
"Yes. I know memories can be swayed.
I know they could be distorted and everything but,
you see, I really am sure that happened."
You have to resist that temptation because there are so
many cases we know, including the tape of the girls
that we just saw, where people are entirely sure
things happened. And we know full well that they
didn't exist. Being sure is no guarantee that
a memory isn't false, reconstructed or even
implanted. So, this part of memory has
three main morals. There are many types of
memories. I talked about short-term
memory, long-term memory. I talked about implicit memory
and explicit memory. These are sort of separable
sort of memories. You could break one while
having the other one impaired. Arguably, there are brain
systems dedicated to memory for faces, memory for everyday
objects, memory for spatial locations.
The key to remembering is organization and understanding.
Introduction to "X" courses, including Introduction to
Psychology courses, are among the hardest courses
at Yale. And the reason why is there is
just a lot of material that is diverse and you have to command
each aspect separately. The easiest courses at Yale
tend to be highfalutin seminars where you kind of have enough of
a background that everything is--can be clear and
understandable. The more you understand
something, the easier you'll remember it.
And finally, you can't trust some of your
memories. Your reading response for this
week is you have to use your powers for good and not for
evil, [laughter]
though if you manage to succeed at this I will be very
impressed. [laughter]
But you have to describe, based on the lecture materials
and the readings, how to implant a false memory.
We have a few minutes. Any questions on memory.
Yes. Student: [inaudible]
Professor Paul Bloom: Uh huh.
Hey. Please-- Student:
[inaudible] Is that long-term sensory
memory? Professor Paul Bloom:
The example is, "What sort of memory is it when
you know how to play the piano?" And it's a very good question.
It is long-term memory because you might know how to do a
concerto or a song and then you have it stored in your head and
you carry it around with you. You'll remember it a year from
now, two years from now. It is long-term memory but it
is also an excellent example of implicit memory because you know
how to do it but you could do it unconsciously without attending
to it. It's not sensory but it's as
if, put it crudely, that your fingers know and not
your mind. We have time for one more
question. Yes.
Student: [inaudible] Professor Paul Bloom:
The question is about photographic memory.
There are a lot of claims about photographic memory.
My understanding is they do not tend to be substantiated.
Sometimes photographic memory, and this came up when we talked
about autism a few classes ago, is linked with savant-like
skills. People who have severe
impairments in some ways may have photographic memories in
others. I am not convinced that
photographic memory in the sense that you see something,
you take a picture of it, you hold it in memory really
exists. I think there may be one or two
case studies that suggest it might be real but I think it's
controversial. Okay.
We have a guest lecturer on Wednesday.
Dean Peter Salovey will talk to us about love.