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PROFESSOR: So today we're going
to talk about attention.
And sometimes we talk about
patients who are very unusual.
In the next lecture,
we will do that.
We'll talk about spectacular
disorders of attention.
But today we're going to talk
about attention as it
typically occurs in you sitting
here right now.
I want to convince you that in
addition to slips of attention
that can occur as you get older,
also how you attend to
the world around you is weirder
than you think.
In a broad sense, I hope to
convince you that it's
happening all the time.
Right now, as you go back to
your room, as you walk to the
next class, or your room.
How you attend to what's around
you in the world is
weirder than you think.
So what is attention?
What do we mean by attending
to things?
So William James was a
psychologist at Harvard who,
in many ways, articulated
concepts in psychology that,
till this day, turned out to
be beautiful ways to talk
about them in an
everyday sense.
"Everybody knows what
attention is.
It's the taking possession by
the mind in clear and vivid
form of one out of what seems
like several simultaneous
objects or trains of thought.
It applies withdrawal of some
things in order to deal with
others."
So a big idea there is we can
pay attention to some things
and there's a lot of
things around us.
And so we have to pick where
we focus our attention.
A little bit like if
you have a budget.
If you have some money, what
do you spend your money on,
and what do not spend
your money on?
So we're going to talk
about attention.
It's kind of similar to
the idea of awareness.
What are you aware of?
Or what are you conscious of?
And two themes across the talk
will be we often attend to
more than we realize.
And I'll show you very specific
evidence for that.
But we often attend to
things less than we
realize all the time.
And here's roughly
the outline.
We're saying attention, what you
pay attention to, is kind
of a gatekeeper to what you
perceive and what you know.
Attention is very limited.
We can only process one
thing at a time.
And because of that, we miss a
lot around us all the time.
There are unconscious processes
that pick up
information.
So sometimes things that we
don't notice do influence us.
And attention can be
viewed as kind of a
dialogue between two things.
Between things in the world that
capture your attention.
If somebody throws a ball at
you, something dramatic
happens-- you hear a scary
sound that captures your
attention--
we talk about that as
"bottom-up" processing.
It impinges on you.
It forces you to attend to it.
Because it's danger, it's
moving, it's unusual.
And then, "top-down" things.
What's your goal?
What are you paying
attention to?
What do you care about?
What are you up to?
People call that top-down
processing.
So things that the environment
drives into your attention
because they're so dramatic,
bottom-up.
Things that you're looking for,
thinking about, you know
are useful for your purposes,
top-down.
There's tremendous evidence that
we encode a very small
fraction of what's around us
in a very specific way.
Estimate with me how often a
day, on average, since you've
been about five or six or seven
and you've been allowed
to have any money in your
possession at all.
Do you think you've held
or seen a penny?
OK, so we all know the
horror when you're
handed $0.4 in change.
That's 4 pennies right there.
So we'll make an estimate.
Pretend from age 5 to 20 you've
been handling change.
So maybe you've encountered
3 pennies a day.
OK, that's reasonable?
OK.
We don't have to be just
in the right ballpark.
There's 365 days a year,
skip 15 years.
Just do the multiplication.
You end up with about 16,380
penny experiences.
All right, so we all know that
if you head towards midterms,
it's going to be hard to study
a lot of stuff quickly.
But if somebody said to you,
if you study something
approximately 17,000 times,
you'd think, well, that one
I'm going to get.
So let's ask the question.
Does the Lincoln penny face
to the left or the right?
Is there anything above his
head or below his head?
Is there anything on the penny
to the left or to the right?
And how about the other side?
And how many of you with
approximately 17,000, or
certainly many thousands of
visual experiences with a
penny would bet something that
means a lot to you on the
correctness of your answer to
these 5 fundamental questions?
This is good teamwork.
Let's take it multiple choice.
That's better, right?
AUDIENCE: It faces the right.
PROFESSOR: You're making
me feel better because
of the fouls up.
And I appreciate that.
This is actually what
it looks like.
So what do you think it means
that 17,000 exposures to a
penny don't leave in you a
reasonably accurate memory of
the main things you
see in a penny?
How could that happen?
And it happens to everybody.
In fact, when they
do experiments,
here's people's drawings.
Don't feel bad if you
didn't know it.
Half the people don't even think
that the version that
you show them, if you ask them
is plausibly correct, you show
the correct answer,
they go no.
That can't be right, OK?
So here's one thing.
If we don't attend to something
very specifically,
we can see it a tremendous
number of times and it leaves
no impression on our mind
and no memory of it.
Now, why is that in
an everyday sense?
We don't know on a deep
science sense.
But what do you think
the point of it is?
Why don't you know what
a penny looks like?
Because it's not important
somebody said.
Yeah.
Because it's close enough to see
that brown smallish thing,
and you don't need the rest of
any information to hand the
money back and forth.
So what you attend to, what you
decide is important, makes
incredible difference.
And nothing else makes
up for it.
17,000 exposures don't make up
for what a penny looks like.
So, it was research at MIT
that used this method of
simultaneously processing two
messages in the two ears, the
shadowed message, the one you're
copying, and the second
message, the one that you
try to pick up, but
it's hard to do.
So they ask in the ear that
you're not paying attention
to, what can you pick up?
Here is what you can pick up
if a voice is present.
Now you just imagine silence
versus somebody talking.
That you can notice.
If the voice changes from
a man to a woman--
if it changes from a man to
woman, you can pick that up in
the unattended ear,
the one you're not
paying attention to.
Or if the voice goes-- a
person's talking and, all of a
sudden, it goes er.
You notice that.
Here's what you don't notice.
Anything about the content.
I mean, that's what
you experience.
You can switch the language
of the message.
You can go from English to
Spanish, or Italian.
A person won't notice
that it's changed.
You can also change whether
it's typical speech or
backward nonsense speech,
which sounds very weird.
You don't notice that either.
So you notice a few things.
But there's a lot of
other things you
don't notice at all.
Now, you may have all had the
experience of what's called
the cocktail party phenomenon.
Do you know what that is?
Have you ever been talking with
people, you're at a party.
You're at some events, or
something like that.
And somebody mentions
your name.
Especially your first
name, but your name.
Maybe your last name
works, too.
And then all of a sudden,
you notice a
conversation around you.
It's almost hard to pay
attention to the person you're
talking to because the person
over there has just said your
name and you wonder what they're
saying about you.
Now, here's a really interesting
paradox.
How did you not notice
that other
conversation, which you didn't?
That's like the shadowing
task.
I'm talking to one person,
there's some hubbub over here.
I don't know what they're
talking about.
All a sudden, they say my name
and I notice what they're
talking about.
Well, how did that happen?
I wasn't paying attention
to it.
I don't know anything
about it.
But my name pounced out
in my mind and drew my
attention to it.
So it's kind of a paradox.
I'm not paying attention, but
somehow I pick up my name.
And so we'll talk a little
bit more about this.
But people have looked at this
very experimentally.
So here's how they
approached it.
They would, again, hear a
sentence in one ear, "The man
approached the bank." That's
the one they're repeating.
And in the other ear, they
would hear one of two
different words.
In the unattended ear, they're
not getting much out of that.
They would hear the word "money"
or "river." So now the
bank could be interpreted as
you went to the bank to
deposit your paycheck, or you
want to the bank to have a
picnic by the river.
Two different meanings of the
word "bank" are suggested by
the word you hear in the ear
that you're not processing
information in.
And then the people tell you,
well, tell me what the
sentence is you just
heard, kind of.
And people are primed to give
the interpretation of the
sentence that goes with the word
that's suggested in the
ear they weren't listening to.
So something in their mind and
brain heard enough of that to
influence what they're
interpreting in
the attended ear.
Here's another example.
They're shadowing, they're
paying attention and repeating
aloud an essay in one ear.
And in the other ear, they hear
something that's like a
word "taxi fare." And they pick
words that are spelled
two different ways, homonyms.
So the word F-A-R-E
or F-A-I-R.
Now, if you were typically--
if I ask you to write down the
word "fair" and spell it
correctly, you might say, well,
which one do you want or
something like that?
But if I didn't tell you
anything, most people would
put down the word F-A-I-R
most of the time.
It's a more common word.
But what they found is this.
They finished the experiment.
They shadowed one thing.
They had a word like "taxi fare"
in the unattended ear.
And they said, well, did you
notice you got that word?
Well, if you listen to it, you
remembered you heard "taxi
fare." But if you were shadowed,
you pretty much--
you very rarely remembered
that you heard it.
So it's not consciously
available to you that you
heard it because you were so
busy in the other ear.
And in your mind, listening
to that ear.
But if you're asked to spell
the word, how often do you
come up with the rare spelling
because of what you
heard in your ear?
It's exactly the same.
So part of your mind heard that
word, thought about that
phrase "taxi fare." And when
somebody says to you write
down the word "fair," your mind
got moved to think about
the alternative spellings.
Your unconscious processing of
that content has influenced
you in experimentally
verifiable way.
So what this shows, if you go
back to the cocktail party
effect, which is the everyday
kind of version of this, is
that weirdly enough some kinds
of things that we don't pay
attention to have such
a property that in a
machine-like reflexive way our
mind brain process it to some
extent anyway.
And then there's something
curious that we don't
understand deeply, which is
somehow if it's your name,
it's going like, I'm
hearing my name.
I'm hearing my name.
Pay attention over here.
That's a deep psychological,
computational theory.
And somehow you pull it out
because it's triggered your
mind enough.
Because our names are
so important to us.
Yeah?
AUDIENCE: Is this similar
to [INAUDIBLE]?
PROFESSOR: OK, tell me again.
So the phenomenon where if you
notice a word-- go ahead.
So tell me again.
Sorry.
AUDIENCE: Like you're just
looking around and suddenly a
specific word [INAUDIBLE].
PROFESSOR: Yeah.
It's very much aligned
to the same thing.
The question was, something pops
in your head-- a word--
and then you look back and
you go, wait a minute.
I just read that, but
I wasn't even
thinking about it or something.
Somebody said it or
it's on a sign.
But yes.
Some experience you're not
paying much attention to tips
your mind to think
a certain way.
And all of a sudden you're
thinking that way and you
don't know what tipped
your mind that way.
That's very similar, yeah.
So again, the message here is,
as you're walking around in
the world, there's very few
things that you're very
specifically really aware of.
And many things can change
on you in these examples.
So one of the reasons-- this
is just a thought that by
being selective in attention,
you can focus on what you want
to focus on.
It's not only a weakness,
it's a strength.
So you could pick out the
message in red or you could
pick out the message in blue.
Where you attend helps
you select
information that's relevant.
But here's two more works.
Almost all the examples I just
showed you were from Dan
Simons, who's done really
beautiful work in this way.
Made it very available to--
so here's two YouTube ones.
Sometimes people have said, OK,
these are cute laboratory
things where you're having
people counting.
But the real world
is different.
When I'm out of the classroom
and I'm out of the laboratory,
the real world you kind
of notice a lot more.
Because it's real people,
real situations.
So this is one more
example that's a
beautiful example of this.
So do you think it would have
worked if the replacement
person was very different?
If we was a man or a woman, of
if a very taller person versus
a person not--
no.
But what does that mean?
Why does it work for this one?
And why would it-- it means
that in the person's head,
they have a very rough picture
of who they're talking to.
Does that make sense?
So there's a lot of room
for replacement.
Not total room, but a
very rough picture.
But it's right in
front of them.
OK, now, you've seen this thing,
so I won't do it as a
demonstration now, where people
simply read the words,
the red, orange, brown.
And that's easy because you're
a very automatic reader.
If you're a typical adult, you
read about 250 words a minute.
Zoom, zoom, zoom.
But if you have to name the
color of the print when the
print is contradicted by the
word, so you're reading the
word red printed in green, but
your job is to say green.
That naming of the print when
the word is not matching the
color of the print slows
people down.
They make mistakes.
They're slower.
And that's because there's
a big lesson in this.
It's great to get automatic
at things.
That's how we're skilled at
things-- speaking, driving,
everything physical.
We don't even think
about how we walk.
The price of automaticity
being really skilled and
reflexive is you lose control.
You lose control.
So you don't want to think about
what that word says, but
you can't help but.
Now, let me touch
one more thing.
How many people think-- and just
be honest in your seat--
that hypnosis is kind
of bologna?
OK.
All right, a lot of you.
This is MIT, right?
OK.
So I'm going to tell you that I
think a lot of hypnosis, the
kinds of things where if I learn
how to hypnotize people,
then they can all vote for me,
or something like that, that
doesn't work.
And people who are serious about
hypnosis will tell you
that hypnosis is in the person,
it's not in the
hypnotizer.
It's in the person, it's
not in the hypnotizer.
And it turns out that, in ways
that are not well understood,
there are some people who are
highly hypnotizeable and some
people who are not.
So this is why I think
we're suspicious.
Because if we're not, we're
going, well, they must be
faking it, or pretending,
or whatever.
But let me tell you what they
did and let me see if this
convinces you at all
as an experiment.
So they told people sometimes to
read those words where it's
confusing because you're reading
the color of the print
and the word is contradictory,
it slows you down.
They told them, imagine those
characters are characters in a
foreign language that
you do not know.
Would the content of the word
mess you up for the
color of the print?
No.
Because if it's a language you
don't know, it's just stuff
and you can just name--
OK?
And they asked them
to imagine that.
Now, here's what happened.
For people who are low
hypnotizability, you can give
people questionnaires and
they're pretty good at these
kinds of measures.
They're slowed down by about a
tenth of a second per word
when the information
is contradictory.
And when they're asked to
imagine it's a foreign
language, it's about the same.
The low hypnotizables, you can
tell them, imagine it's a
print you don't know.
It doesn't matter.
Here's the high hypnotizable.
Also slowed down.
But when they imagine it's a
print in a foreign language
they don't know, not
slowed down at all.
So that's behavior.
That's evidence.
And we don't think you can
fake it because how
would you fake it?
But here, in case you were
still worried about that,
here's the brain imaging
evidence from just the people
with high hypnosis, the high
hypnotizable people.
What you see here turned
on is the part--
our brain areas are turned on
when you have to do the
difficult task where
it's contradictory
versus the easy task.
All this area you see turned on
in the anterior cingulate,
and especially--
which is an area that we know
is involved when things are
contradictory or paradoxical and
people are sorting it out.
Look what happens to that when
these individuals are
imagining it's a foreign text.
It's pretty much gone.
Is that OK?
I'm as skeptical as anybody
about behavioral
claims, I really am.
I think hypnosis is real for
some people and very powerful
for some people.
And for other people it
doesn't work at all.
I happen to be in the low
hypnotizable category.
I'm as skeptical as anybody, but
I think there are people
who can do remarkable things
by hypnotic suggestion.
But it's in them, it's not in
the-- a person who hypnotizes
you, so to speak, can help
you a little bit.
But it's in you whether you have
that approach to control
of your thoughts or not.
So let's go back to a test.
So we're talking, again,
about two ideas.
That there's things--
top- down and bottom-up
processes, and different ways
that you can attend
to the world.
So I'm going to ask you to
consult your own intuitions
for the following thing.
I'm going to show you things
displayed on the monitor.
And your job is simply to answer
in your own mind as
quickly as you possibly can.
Maybe just, if you're willing to
do it out loud, let's just
say yes or no aloud, if you're
willing to do it.
As quickly as you, whether you
see a red X. Sometimes there's
a red X, sometimes not.
So ready?
Sorry, that's my get ready.
AUDIENCE: No.
PROFESSOR: No, great.
See, MIT is easy.
Sorry.
OK, ready?
Red X or not?
AUDIENCE: Yes.
PROFESSOR: Great.
Ready?
OK.
Thank you.
Ready?
Red X or not?
AUDIENCE: Yes.
PROFESSOR: Whoa.
You guys are amazing.
Now, look how many places you
had to look to find it.
But did it feel that way, or
did it seem to, what they
call, pop out?
It's just obvious.
It's just there.
So imagine I gave
you this task.
I said, go into this room and
please get a particular book.
And you go into the room and
there's one book there.
And you've picked it up.
Would that be easy?
Yeah.
You go into a room and you go,
my gosh, there's hundreds of
books in this room.
Would that be easy?
Now, here are many, many more
things to find the red X. But
your mind instantly, easily,
trivially finds it, right?
So now, let's try another
version of this.
AUDIENCE: Yes.
PROFESSOR: Yes?
OK, get ready.
AUDIENCE: Yes.
PROFESSOR: All right.
Slower?
Harder?
OK, some disagreement.
OK.
All right, so let me show you
data under well controlled
conditions.
And here's the concept.
People think that in many ways
when we look out in the world,
there's features, things
like simple things--
shape or color.
Those are the two we're
looking at here.
But in order to combine those,
to know the same thing out
there has this shape and this
color, to glue together
features, we have to
have attention.
And so when the display looked
like this, a single feature--
redness--
helps you.
A single feature-- redness--
helps you.
You don't have to worry
about the shape.
Now, you have to worry about
the shape and the color to
decide the red X. Worse
yet, now it's a
slower, harder process.
And when people do this, here's
exactly what they find.
If it's just a feature by shape
or by color and that
alone would tell you the answer,
you can have one
thing, a few things,
and many things.
And boom, your mind instantly
discovers it.
Instantly.
This is how long it takes
you to do it.
But if you have to combine two
things together, the shape and
the color on the very same
thing, combine those things,
you need the glue
of attention.
And the more things that are out
there, the more your mind
has to search, search, search,
search, until it
finally finds it.
It has to look around, and look
around, and look around
to find the answer.
So some kinds of things in the
world we notice without
attention features.
We can look everywhere at
once in the display.
That's how we're so fast.
Things just pop out.
And the flat slope is--
mathematically.
Doesn't matter how many things
are out there-- boom, you get
it right away.
Other things where we have to
glue together two features
require our attention
to do the gluing
things that are together.
We have to search spot,
spot, spot, serially.
We don't feel the intuition
of pop-out.
And we have a steep
slope in search.
Now I need somebody from their
chair who's pretty confident
in their math.
It's a little bit harder than
before, but I'll tell you
don't have to go into
triple digits.
Someone help me.
I owe you one.
I'll come back to you
if there's one more.
I can't remember, sorry.
OK, ready?
So you're going to see some
numbers and I want you to add
them and tell me
what they are.
And I'm going to
be pretty fast.
Is that OK?
AUDIENCE: [INAUDIBLE].
PROFESSOR: [INAUDIBLE].
AUDIENCE: OK.
PROFESSOR: Yes.
OK?
Ready?
AUDIENCE: 14.
PROFESSOR: Yes.
Ready?
AUDIENCE: 5.
PROFESSOR: Yes.
Ready?
AUDIENCE: 10.
PROFESSOR: Yes.
Ready?
AUDIENCE: 13.
PROFESSOR: Yes.
Now what were the letters
between them?
Sorry, it's a trick.
It would have been mean.
AUDIENCE: [INAUDIBLE].
PROFESSOR: Sorry?
AUDIENCE: [INAUDIBLE]
the last one so far.
PROFESSOR: Interesting.
OK.
Now, you can go, oh,
that was a trick.
How reasonable is that?
Well, let me make the argument
that in order to add the 5 and
the 8, you had to look
at the letters.
You had to look at
the letters.
They're in the middle.
But because your mind is not
attuned to that, it's as if
they weren't there almost.
You know some thing's
there, right?
It's right in front of you.
It doesn't seem that hard.
But again, if your mind is tuned
to something, the other
stuff gets fuzzy.
And you got the R somewhere.
Now, let me ask one
more question.
Do you the colors the
letters were in?
No.
And in fact, you don't.
So thanks very much for
willing to do that.
So again, we just said to bind
shape and color, we need the
glue of attention.
We're not attending to
the middle letters.
They seem irrelevant
even though they're
right in front of us.
Even though we have to walk
through them in our mind's eye
to move from one number
to the other.
They're like, I don't care.
Boom, you move to
the other side.
So it's not just seeing
something, it's attending to
something that really matters.
And on top of that, you need a
lot of attention if you do
glue together the shape
and the color, that
requires a lot of focus.
What does this mean
in everyday life?
In everyday life, we're probably
walking around
constantly having free floating
features around us
and things we're not paying
attention to.
Right now I'm probably seeing a
yellow computer over there.
And I'm seeing some blue fire
extinguisher sign over there.
Now, why am I not freaked
out by that?
And why are you not freaked
out by that?
And why is it almost certain?
Because if you're not attending
to things, you're
constantly having free floating
features that are incorrect.
Colors and shapes are just
floating around you.
Why are we not disturbed
by that?
Because we're not attending
it to start with.
Because it's like you didn't
notice the letters were there.
Well, then you're
not bothered.
They're just free floating
information.
You're not paying attention
to it to start with.
But that's what's happening
in your mind all the time.
And these experiments
demonstrate that empirically
and directly.
There's also interesting
temporal constraints.
I'll describe this experiment
because it's too
hard to pull off here.
So there's a phenomenon called
the attentional blink.
What's weird about these
things, right?
Why is our minds like this?
You can speculate on that, but
it's really well documented.
We attend to a small
percentage of
what's around us.
And we need a lot of resources
to know something well or
learn something well.
So here's another example.
What participants see is letters
presented very quickly
one after the other--
E-L-H. Their job is to report
any numbers that they see.
So you go, boom, boom,
boom, boom.
What were the numbers?
Pretty fast, but humanly
possible.
The interesting question is,
what's the time gap between
the two numbers that you see?
There's usually two numbers.
We'll call this one the
first one, time 1.
The second one, time 2.
What's the gap between them,
and how does that influence
whether you're likely
to report them?
So here's what's called the
attentional blink and a
slightly scary graph
that I'll tell you.
And let me tell you what it's
like, the metaphor, and then
let me show you the result.
The metaphor is this.
Your mind, moment to moment to
moment, is kind of like if you
could imagine you're next to a
stream, a big stream with a
lot of fish zooming by.
You have a fishnet.
You dip into the stream.
You catch something
at that moment.
But if a fish comes by just as
you pull your fishnet out,
will you catch that one?
No.
So here's what happens.
Here's the time between
the presentation.
If there's approximately three
numbers between them, a couple
hundred milliseconds, you're
almost a chance for the
possibility of reporting
the second digit.
It's sort of like the fish you
can't catch because you just
took your net out.
Except it's your mind, it's
not a physical limitation.
So here's what it's like.
So this is perfect
performance.
This is chance performance.
If it immediately follows, one
number immediately follows the
next number, you're
going to get both.
And the way to think about that
is, it's kind of like
fishnet again.
You just put in your fishnet.
You got one fish.
And if you're lucky, while
you're kind of pulling it out,
the next fish just
swims in there.
You got two.
Now your fishnet's out.
And if something else comes, and
something else comes, and
something else comes, you're
pretty bad at recognizing it
was there at all.
A little bit of time comes back
and you put your fishnet
back in and you're catching
everything again.
About 1/2 second.
But how weird is that that your
mind works like that for
spotting the digits?
That it has to take a break?
There's a part of your mind
that's getting the digits.
And once it's gotten a digit,
for the next couple of hundred
milliseconds, it's not going to
have room to pay attention
to the following digits.
How weird is that?
It's because our mind has all
these kind of limitations on
what we perceive in
the environment.
Here's another sort of
fun example of that.
So here's a task.
One of these dots
are going to--
One dot is going to blink.
And your job is to keep
your eye on that dot.
You know when they say, keep
your eye on the ball.
Keep your eye on the dot.
And when it stops moving, notice
which is the one you've
been keeping your eye on.
So the first one's going
to be easy, but it
will give you a feeling.
And then you'll see the
answer given to you.
Ready?
People call this object
tracking.
OK, here we go.
See that one blinking?
Now, let's try it one thing
moving, but even faster.
So let's try tracking
four things.
Last example.
So here's a graph with
a high level of
performance how people do.
So two things matter, and you
might have felt that.
How many are viewing the
number of targets?
And under many circumstances,
people seem to be able to do
about three to four.
But also, the speed
matters, too.
You might have felt that, too.
Both things contribute.
There's a lot of interest in
this three to four limit that
people seem to have for things
that they track,
three to four items.
And there's a lot of work,
at Harvard actually, in
developmental psychology
and related.
Let me just say a word
about that to you.
There's a thought that pretty
young when you're a kid, you
get to about this three
to four things.
That our minds naturally
contract about, or notice, or
keep a count of about three to
four things in the world.
And so people who study, for
example, math and the way that
humans perform it, think that we
have in us, in our brains,
approximately two systems that
are physically different and
culturally different.
And there's lots of debates
about this, I
should tell you this.
But one of them being something
like accurate
counting up to about
three or four.
And then, cultures that don't
have a organized system of
math, the next answer is many.
You've heard this, right?
It's like one, two, three, maybe
four, and then a lot.
Now, we don't stop counting at
four, but we might if we were
in a true state of nature and
we didn't have an organized
system of math.
And weren't taught that
in how it relates to
our language abilities.
So there's a lot of debate about
the exactness of this.
But there's something
fascinating about this idea
that our minds can have about
four units of information kept
in mind, kept active,
that we can track.
And that lots of things in the
world reflect that limitation.
Including, for example,
exact counting.
And without the cultural
invention of mathematics, we
would count one, two,
three, four, lots.
But there's debates about this
because exactly how you
measure it can influence
how you think about it.
Now, can attention be trained?
Could you be trained to have
much more attention?
So in many ways, we don't
think you can.
But in some ways, you can.
And part of this has come out
of this ironic line of
research about things that are
supposed to be bad for us.
Some of them might
be OK for us.
Video games, OK?
If you're in my generation,
people are going, oh, boy,
those video games are messing
up all these kids.
Isn't that what you
guys think?
No.
OK.
So Daphne Bavelier at Rochester
has done a series of
studies showing that if you play
certain kinds of video
games, you actually do expand
your attentional capacity to
practice on those games.
Because they make you
practice a lot.
So here's what she did.
She took people who didn't
have experience
playing video games.
And now we're specifically
talking about first-person
shooter video games.
And had them do 30 hours
of practice.
And she looked at their ability
to do multiple object
tracking of the kind you just
saw, those dots whizzing
around, before and after.
So the games, as you know,
are very different.
But they involve keeping
track of lots of things
happening at once.
And here's what she found.
That these people who played
30 hours, these were people
who were not gamers beforehand,
got better at
performing these tasks
of keeping
track of multiple objects.
Of all things, a group that's
super interested in that is
the military.
And why do you think that is?
AUDIENCE: [INAUDIBLE].
PROFESSOR: OK.
There was just a paper published
recently that if
they take a brain image of your
brain, they can predict
how good a gamer you'll
become if you haven't
been a gamer before.
These are adults.
If you have bigger basal
ganglia, you'll become a
better gamer in the next week
starting from scratch.
The military's interested
because you may know this.
An increasing amount of warfare
is video game-like.
Which is kind of the
haunting thing.
Because this is real people
really being killed.
But, do you know the whole
thing with the drones?
Have you followed this,
some of you?
OK.
So the US has had a lot of
success, and there's a lot of
debates about the ethics of
this, in sending in unmanned
small airplanes into
the Middle East.
And using that to
kill opponents.
The person sitting in
Washington, DC, or somewhere
else, is watching kind of like
a video game when they make
that decision about
whether that's
somebody to be attacked.
So a lot of operations now are
computer-based and they're
kind of like a video
game at one level.
And they're real-life hard
decisions at another level.
So video games, they're becoming
more and more, as you
can sense, a part of real world
decisions and controls.
If you play Tetris because it
doesn't require that kind of
fast thought stuff, you
don't get any benefit.
There could be other benefits,
but not this one.
So it's not just video games,
it's the mental processes that
are practiced in the video games
that give you certain
talents or not, or abilities
you didn't have before.
OK, the last experiment I want
to tell you is this.
So everything we've talked about
now, except a little bit
about the stuff in the second
year when you're shadowing,
has been about this idea that we
don't pay much attention to
what's around us.
We don't get much in our mind
compared to what we think we
would, even if it's right in
front of us, even if it's all
over the place.
Even if we've seen a
penny 17,000 times.
But there are some studies
that have shown something
pretty interesting also, which
reveals something very
paradoxical about
the human mind.
That we can sometimes know
things without seeing.
And people call that subliminal
perception.
So how this experiment
works is this.
And let me show you one
example behaviorally.
I'm going to show you
one brain example.
So here's what happens.
Let's pretend you have
to read words aloud.
And we measure, to the
millisecond, how fast
you read the word.
If I show you this word and I
show you this word, and I
measure how quickly you read
the word "doctor," you're
slower than if you read the word
"nurse" and then you read
the word "doctor." Because
these two are related.
And something in your
mind gets warmed up
when you see this.
It doesn't get warmed up
in a relevant way when
you see this word.
Does that make sense?
You see one word and then
you read the next one.
If they're related semantically
or conceptually
by meaning, you're faster
for the second one.
OK, that's easy.
And it's not too surprising.
The clever discovery was this.
What they do is they do
something call-- they present
these words under what they
call masked conditions.
On the computer monitor you
get something busy, like a
roll of X's.
For 10 milliseconds only,
ten-thousandths of a second,
the word appears, and then
there's a bunch of X's again.
So it's like a flash of X's.
And people, they create
situations--
and I'll show you this
again in a moment.
They create situations where
people say, I'm not sure
anything was there.
I certainly don't
know what it is.
You have to be there and you
have to convince yourself, as
a scientist, that you've
done that.
And then they have
you read the word
"doctor" in full view.
And in these circumstances where
people cannot tell you
that they saw a word, and they
certainly can't tell you what
the word was, you still
get faster.
So they don't know that they saw
"church" or "nurse," but
something in their
mind picks it up.
And what's picked up in the
mind under the subliminal
presentation changes the
behavior when you have an
overt act of behavior reading
the next word aloud.
So this is hardcore empirical
evidence that your mind is
able to pick up stuff at
the level of meaning.
Think about the paradox.
You think when I read a word, I
see it and then I understand
its meaning.
Here it's flashed in such a way
that you don't feel like
you see it, but you extract
its meaning anyway.
And we know that because it
makes you read the next word
faster only if they're
related in meaning.
So your mind is subliminally
primed.
Now, some years ago people used
to worry that advertisers
could do this really cleverly
and make you go do stuff.
The famous example is
historically, can they make
you buy popcorn?
Which is now, since it's $48,
that's harder to do.
But can they make you buy
popcorn at the movie theater?
Or can they make you buy a
Ford, or a Chevrolet, or
something like that, with the
right subliminal message and
that kind of stuff?
Every experiment that's been
done to ask whether subliminal
messages of this kind would
make you get up and go do
something, like buy a car, or
change what country you live
in, or something,
it never works.
It never works.
Nobody's ever been able
to show that in any
experimental condition.
Which doesn't prevent some
companies from selling these
products to store owners that
are thinking they're getting
their sales up.
But there's been never any
evidence that these kinds of
subliminal presentations make
people do something big and
complicated, like get up and go
buy popcorn, or choose one
product over another.
People have never been able to
show that under controlled
experiment.
But they have been able to show
these kinds of changes in
behavior that last a moment.
So what's happening
in your brain?
So this is the last
experiment.
Again, they're presenting these
things that in the same
place in the computer monitor
all these things
to fill your eyes.
And then they present a word
for either 29 milliseconds-
they present it either very
briefly or in full view.
OK, so here it's visible
because they remove the
confusing visual information
just before and after it.
Here, people don't
report seeing it.
And scientifically, it's really
important because you
just say, oh, people
didn't see it.
But it's really important
in our field to
say, we're so convinced.
And why are we so convinced?
Because we say, was there
any word present?
Because sometimes there's a
word present and sometimes
there isn't.
Just is there a word present?
If you could see the word,
because these things were a
little bit away in time and you
could see it, you almost
always got it if
it was visible.
You almost never got
it if it was here.
You almost never said there
was a word present.
And could you name it?
Yes, if you saw it like this.
You couldn't name it if it was
presented brief-- if it was
surrounded by this
visual stuff that
makes it hard to see.
If they give you a memory test
for it, if you saw it fully in
full view, you got it.
If it was hidden like
this, you didn't.
And finally, they give
you a fourth choice.
They say, did you see the word
"note" or did you see the word
"coat?" Choose between
the two.
People are still at
chance 50-50.
They're really pushing
people to say,
really, did you see anything?
Do you know what it was?
There are completely a chance
they don't remember anything.
They can't even tell if
a word was there.
But we know it influences
their mind.
And now let me show you what we
know of how it influences
your brain.
So what's shown here in green
are parts of your brain that
respond when a word is shown
that you can see.
And what's shown here in red
are the parts of your brain
that respond for that
subliminally presented word,
the word that's presented but
you can't tell that any word
was there, never mind
what word it was.
So at first you can see there's
a lot more brain
response for the visible than
the masked or subliminal word.
But that makes a lot of sense.
You see something, you think
about, you know it happened.
But you can measure what's
happening in the brain.
It's very small.
Take this spot.
Here's the response if
it's in full view.
Here's a tiny, tiny, tiny,
tiny response when it's
presented in that
minimalist way.
But it's measurable
and it's present.
And we know that it's enough
for you to figure out
unconsciously what the meaning
of that word was.
So then, we ended with this
paradox, which is on the one
hand, we live in a world where
we only notice a small
fraction of what's around us.
What we focus our attention
to because we have limited
attentional capacity.
On the other hand, there are
channels of information that
sneak into your mind.
That probably influence you only
for a few moments in the
unattended ear, in the
cocktail parity.
You're actually picking up that
conversation because if
they say your name,
you'll get it.
Here's an example where your
brain is responding to a word
you cannot identify or know
that it was presented, and
those things can slightly move
your behavior around.
But not in a science fiction or
marketing dream that they
could make you go do something
really big.
OK, that's never been shown
and people have
tried to show that.
So attention is really weirder
than you think.
You don't notice a lot of stuff,
but a few things you
don't think are influencing you
are influencing you here
and there all the time.
Thanks very much.
