- Welcome everyone to Wednesday
Nite @ the Lab.
I'm Tom Zinnen, I work here at t
he
UW-Madison Biotechnology Center.
I also work for the Division
of Extension.
And on behalf of those folks, an
d our other co-organizers,
Wisconsin Public Television,
the Wisconsin Alumni Association
,
and the UW-Madison Science Alli
ance,
thanks again for coming to Wedn
esday Nite @ the Lab.
We do this every Wednesday night,
50 times a year.
Tonight it's my pleasure to in
troduce to you Emily Ward.
She's an assistant professor in
the Department of Psychology her
e.
She was born in Santa Cruz, Cali
fornia.
And went to high school at-- ex
cuse me,
at Pacific Collegiate School in
Santa Cruz.
And then she did her undergraduat
e degree
in neuroscience
at Franklin & Marshall in Lancas
ter, Pennsylvania.
Then she went to Yale, to get
her master's
and her PhD in psychology.
Then she did a postdoc at the Don
ders Institute
in Nijmegen, in the Netherlands.
And then she came to the UW-Madis
on here,
and the Department of Psychology
, in 2017.
Tonight she's gonna talk with us
about
Seeing and Not Seeing:
Investigating Visual Awareness.
Let's see what she has to say.
[audience laughing]
Look forward to hearing this
, please join me
in welcoming Emily Ward, to Wedn
esday Nite @ the Lab.
[audience applauding]
Thank you very much.
- Thank you all for coming out.
I'm very excited to be here.
This is my first time as par
t of this series.
And I'm excited to talk about so
me of my research.
So, as a psychologist, I'm intere
sted in the mind.
And in particular, I'm interest
ed in
the relationship between the mi
nd and the world.
How does everything that's out
here, get into the mind?
And the first step in understandi
ng
the relationship between the mi
nd and the world,
is understanding how we become
aware of the world to begin with.
This may seem very straightforwar
d,
after all, we walk around every
day,
seeing things, noticing things.
So this may seem like a weird ty
pe of topic to study.
But what I hope to show in this t
alk,
is that this relationship betwee
n the mind and the world,
is governed by our awareness.
And that what we become aware
of, is not
as straightforward, and can be v
ery counterintuitive,
and interesting in many ways
that you might not
ordinarily think about.
So, to motivate my research, I wa
nt to present an example
that I hope not too many of you h
ave experienced,
to give you a sense of how ther
e is a disassociation
between what goes on in the worl
d, and our awareness of it.
And that example is a car crash.
So just to put what you just saw
, in perspective.
Make it a little bit more concret
e.
This is a timeline of what went o
n, in that previous film.
At zero milliseconds, the extern
al object hits the car.
The events unfold, such that at a
bout 27 milliseconds,
the impact velocity is halved.
The airbag is starting to control
its deflation.
So on and so forth.
At 70 milliseconds, the airbag c
ontinues to deflate
and the occupant moves back to t
he middle of the car.
And what's interesting is, at
this point,
the 70 milliseconds,
this is what engineers would say
is a completed car crash.
And so, one thing that might be
missing for you in this pictur
e,
is that it's not until a 150 to
300 milliseconds
after the initial impact of the
car, that the occupant
even becomes aware that a crash
has occurred in the first place.
And I like this example, because
it gives you an idea
of this disassociation between
the mind, and the world.
And some of my research has been
focusing on that disassociation.
In particular, looking at spect
acular examples,
where we fail to become aware of
things in the first place.
So in the course of this talk,
I hope to convince you of three t
hings.
The first is that you don't see
as much as you think you see.
The second is that what you d
o see, can be
surprisingly sophisticated, and
counterintuitive.
And finally, I'll end with someth
ing a little fun,
talking about how your awareness
can be altered
by information that you don't ev
en know
exists in the first place.
So a car crash is a little gr
im to start out a talk with.
So I'd like to give another exam
ple,
[audience laughing]
of how your sense of what you can
be aware of,
is a little different than maybe
what you think it is.
So there's no task in this part,
you guys can just watch this vid
eo.
[lively piano music]
- Clearly, somebody in this room
, murdered Lord Smythe.
Who, at precisely 3:34 this afte
rnoon, was brutally
bludgeoned to death with a blunt
instrument.
I want each of you to tell me yo
ur whereabouts
at precisely the time that this d
astardly deed took place.
- I was polishing the brass in t
he master bedroom.
- I was buttering his lordship's
scones belowstairs, sir.
- Why, I was planting my petu
nias, in the potting shed.
- Constable, arrest Lady Smythe.
- But, but how did you know?
- Madame, as any horticulturist w
ill tell you,
one does not plant petunias until
May is out.
Take her away.
[audience laughing]
It's just a matter of observation
.
The real question, is how ob
servant were you?
- Emily: Anybody?
[audience murmuring]
We'll see this again.
- Director: And action.
- Clearly, somebody in this room
, murdered Lord Smythe.
Who, at precisely 3:34 this afte
rnoon, was brutally
bludgeoned to death with a blunt
instrument.
I want each of you to tell me yo
ur whereabouts
at precisely the time that this d
astardly deed took place.
- I was polishing the brass in t
he master bedroom.
- I was buttering his lordship's
scones belowstairs, sir.
- Why, I was planting my petu
nias, in the potting shed.
- Constable, arrest Lady Smythe.
[audience chuckling]
- So, obviously, I'm giving a ta
lk about visual awareness.
And I'm sure some of you were a
little skeptical
that this would be a straight
forward movie,
and were looking for particular
changes.
But even if you did notice some o
f the changes,
I bet none of you noticed 21 of
these changes.
Even though, when you see it
after the fact,
these are pretty big changes.
These are entire people changing,
these are entire paintings changi
ng.
There is nothing very small abou
t these types of changes.
And so what happened here, was
that you collectively
experienced what I'm going to ca
ll a failure of awareness.
This is failing to notice some
thing that's otherwise
pretty noticeable in the environ
ment,
if you were paying attention to i
t.
And some of you are probably fam
iliar
with some of the most famous cas
es of this.
Whenever you're talking about fa
ilures of awareness,
most people out in the world, pro
bably most people
in this audience, most incoming p
sychology students,
are aware of a particular example
,
which is more commonly known as t
he gorilla experiment.
This experiment was made famous
by a group in the mid-90s.
And what happens in this, is that
there is a group playing basketba
ll.
And you as a participant, would
be paying attention
to a subset of the number of play
ers.
So, for example, you might be pay
ing attention to
how often the white players pass
the ball back and forth.
Meanwhile, in the middle of your
task,
which is pretty difficult, keepi
ng track
of the basketball, with only the
subset
of these players in white T-shirt
s,
a man in a gorilla suit walks thr
ough
the middle of the display.
Most people don't notice this
the first time they see it.
If you guys are familiar with thi
s, and this is why
I don't use this, is you do see
it.
Once you're aware of it, you ha
ve an expectation
about what's gonna happen, an
d it undermines this effect.
But this effect, has been called
inattentional blindness.
That you're blind to things you
would otherwise notice
because your attention is engaged
.
But there is, despite how famous
this example is,
there is still a fundamental ques
tion
about what the nature of this def
icit actually is.
Is it in fact, a type of blindnes
s, as the name suggests?
Meaning that this is a failur
e of perception.
That you really just don't se
e that gorilla,
as it passes through the basketba
ll game.
Or is it something a little bit d
ifferent?
Is it a failure of your memory?
And what I mean by failure of mem
ory,
isn't just that you forget
where you put your keys in the mo
rning.
It's something a little bit m
ore subtle.
And so to give you an idea of wha
t exactly I mean
by failure of memory, I'm going
to have you watch
another little video.
In this video, this is what's kn
own as
a rapid serial visual presentati
on display.
RSVP for short, that's not import
ant, what is important
is you're gonna see a bunch of l
etters.
They're gonna be presented ve
ry quickly
at the center of the screen.
And I just want you to pay atten
tion
to them as best you can.
All right.
Can anybody tell me exactly whic
h letters you saw, in order?
[audience murmuring]
You can't, right.
I can't, I've seen this a lot, a
nd I still can't.
But you wouldn't say you didn't s
ee them, in the moment.
If it was anything like my impres
sion,
it's that you have this fleeting
sense
of what you see, and then it's go
ne.
So that's what I mean by a f
ailure of memory.
That simply because you can't te
ll me what you saw
after the fact, doesn't mean
you didn't see it in the first p
lace.
Let me contrast that with the ty
pical story about
inattentional blindness.
Where I'm looking specifically a
t
what you can tell me about it,
what you expect, and what I can
infer about your experience.
So in the inattentional case,
you don't have any instruction
to report what you're gonna see.
You have a task that's keeping
your attention, but nothing else
.
As a result, you have no expectat
ion of what's going on.
And then, your experience is that
you're unable to report what
was present.
Contrasting that with what I
just showed you
with the letters.
A memory deficit gives a very
similar account.
Except that if I wanted to t
est whether or not
you really saw a particular lett
er, I would tell you
to beforehand, clap if you sa
w the letter M.
Or the letter A, I think is my ex
ample here.
So if I give you that instructio
n, to clap
when you see an A, you then expec
t that
you may or may not see an A.
And then you can tell me if you
saw it or not.
And so this is how I would rule o
ut whether or not
you failed to see, or saw a part
icular letter,
in the letter display.
Can I apply this same logic to
an inattentional blindness case?
So for example, if I gave you the
instruction
to report if you saw anything unu
sual,
you would then expect something
unusual.
And in that case, you can repo
rt whether or not
you saw something unusual, like a
gorilla, for example.
But because you were expecting i
t,
that would rule out the effe
ct to begin with.
So the very thing that I'm intere
sted in measuring,
just by telling you that it migh
t happen,
undermines inattentional blindnes
s.
And so you can see that gett
ing around this,
experimentally, is a little trick
y.
How do you figure out if people
are really blind to a gorilla,
or if they're just failing to r
eport in the same way
that you all failed to report the
stream of letters.
So, just to highlight, disent
angling this idea
that this effect might be a f
ailure to see,
or just a failure to remember,
is a bit of a catch-22.
And I think I might have a w
ay around this.
And so I'm gonna tell you about
a minor change
that I made this logic, to see i
f I can figure out
what the true nature of this
effect really is.
So what I did in this particular
study,
is instead of giving you no repor
t,
and having you have no expectati
on,
I wanted to see if I can manipula
te your expectation.
So instead of having no expe
ctation whatsoever,
I wanted to have you expect somet
hing unusual.
But expect only a very particula
r type
of unusual event.
And this, I hoped, would be some
thing that would allow me
to see whether or not people
could report
the presence of something unusua
l, but maybe would
still fail to see something that
violated that expectation.
So, because these types of experi
ments are very famous,
and I can't show people gorillas
out in the wild for example,
we use a different type of displa
y.
And so again we're using simple
letters in this.
And I'll give you a sense of wha
t this looks like.
But what we show participants in
these types of studies
is a computer display where ther
e's a bunch of letters.
Some of them are Ts, some of them
are Ls.
Some of them are white, some
of them are black.
And they're moving around random
ly on the display.
And subject's task is to cou
nt how many times
a subset of them, so in this exam
ple it's the white Ls,
cross that middle line.
So every time they cross that,
you have to keep track of that.
If you wanna give this a sh
ot, I'll show you
what a typical trial looks like.
Any numbers?
- Audience: Five.
- All right, you guys are doing g
reat.
So it's not impossible, but
it's tricky.
You have to pay attention.
And so, because this is a talk,
and I'm talking about inattentio
nal blindness,
I am allowing you guys to know
that something might have happene
d.
Nothing happened on this one,
but when I showed this to sub
jects in the lab,
I had another trial, which is sim
ilar,
except now, something slightly d
ifferent occurred.
How many of you noticed that the
re was a gray cross
that went along the middle of th
e screen?
And how many of you noticed th
e gorilla?
[audience laughing]
All right, so hopefully for
some of you,
you still may have missed that cr
oss.
This does work particularly well.
But there was a slow gray cross,
that was on the screen for about
five to ten seconds.
It's right where you're payi
ng attention,
so I'm not trying to trick you
by having it appear in some perip
heral location.
This is the type of unexpected ev
ent
that I used in this study.
And so how a typical experiment
goes, is that participants
will see about four trials or so,
where only the letters are be
ing presented.
And so that gets them used to th
e task.
And then on the fourth trial, a
red cross appeared in this.
And so it looked something like t
his.
This is a typical way of studyin
g
inattentional blindness.
And what you then would ask is,
"Did you notice anything differe
nt?"
And then ask specifically,
"Did you notice if a red cross ap
peared?"
And if a participant said that th
ey
didn't notice anything, and they
didn't notice a red cross,
I would categorize this as them b
eing
inattentionally blind in this ca
se.
Typically, about 50% or 60% of pe
ople
miss this type of cross.
Previous experiments have stopped
here.
But I decided to keep going.
And I gave people the instructio
n
that any time you see
anything different or unexpected,
immediately press the space bar,
and we'll ask you to identify it
.
So this is giving them the instr
uction
to immediately report what they s
ee in the moment.
Then I continued on with the tria
l structure.
There was a few more trials wher
e nothing happened.
But importantly, there was a
few more trials
where the red cross appeared.
So they were building up this
expectation
that there might be something un
usual.
But that unusual event was the pr
esence of a red cross.
Importantly, at the very last tr
ial,
it was a critical trial,
where half of the subjects saw a
new event.
In this case, it was a blue E, mo
ving
the opposite direction on the
screen.
Or just another instance of the r
ed cross
moving across the screen.
And the question is, if peopl
e are presented
with something that violates the
ir expectation
about what's going to occur,
do more people miss this new, une
xpected event,
compared to just another instance
of
the repeated unexpected event.
So I'm gonna show some data that
answers this question.
So here I'm plotting the percent
of people who miss
the unexpected event on this
critical trial,
by what type of event it was.
Was it the new one, or just t
he repeated one?
So first of all, I measured
how many people missed this r
epeated event.
A few people, while they were doi
ng the counting task,
did miss it, but it's not very ma
ny.
Critically, almost five times th
e amount of people
missed this new unexpected event
.
So this means that more people a
re missing that event
even when they're given that
instruction,
and even when they're willing to
respond immediately
to what they see on the screen.
So what this means, is that you
don't see
as much as you think you see.
And that this phenomenon of inatt
entional blindness
arises specifically due to you
having the wrong expectation
about what's going to occur
out in the world.
And that this phenomenon also ref
lects the limitation
of perception, and not of your me
mory.
So this has implications for the
real world.
This means that if you are driv
ing while distracted,
and a child runs out in front of
your car, and you hit it,
that's not because you saw it
and then forgot,
in the way that you would se
e these letters
that I presented earlier, and for
got.
It's truly reflecting a limitati
on of your perception
because your attention is oth
erwise engaged.
So, this is a good example of
how limited
what we see can be.
But it stands in contrast to what
we think our daily experience
actually is.
So why does it seem like we se
e so much,
when I demonstrated just now th
at our experience
is limited by these limitations
in perception.
So I'm gonna show another video
right now.
No task.
Just sit back and take this in.
So just like before, if I were to
ask you
what exactly you saw, in order,
you probably wouldn't be able to
tell me.
You can recognize these types
of scenes very very quickly
if you know what's going on befor
ehand,
but also if you don't know what's
going on beforehand.
And it also just strikes you as r
eally rich.
You see a lot of detail.
You see exactly what's going on.
These pictures seem evocative.
They seem beautiful, they see
m interesting.
And you can do all this, even t
hough
this is presented very quickly.
So this is in contrast to what I
just showed you,
where we can be really bad at se
eing
noticeable events or changes out
in the world.
But we also feel like we're reall
y good
at noticing rich detail.
How do we reconcile these tw
o experiences?
Is it that we have a limited awar
eness of detail?
But we are instead aware of some
statistical properties
of the world, that make our expe
rience seem so rich.
So, I'll unpack that a little bi
t.
I teach statistics here, so I kn
ow when I mention that,
a lot of people's eyes glaze ove
r.
And they think this is what I'm
gonna be talking about.
That's not really what I mean in
this particular case.
Even in general, it's not re
ally what I mean.
What I'm talking about is,
do we perceive statistical pr
operties?
And so what that means is that
if
I put up a display like this,
and give you guys the task right
now to tell me
what side, right or left, has
the biggest average size circle.
Can you tell me which one you wo
uld guess?
- Audience: Left.
- All right, average is a st
atistical property.
So here, you're doing some compu
tation,
over all of these elements.
And telling me that you can see
that these left side,
contains a bigger average size.
I'm gonna give you another one.
This one's gonna be a little bit
trickier,
and I'm also not gonna present it
for very long.
So again, which side, right or l
eft,
has the bigger average size circl
e.
- Audience: Right.
- Right, okay, you guys are doing
great.
So that's completely true.
And what's interesting about what
you just did,
'cause those were only presented
for about a second or so.
So it's enough time to do a l
ot of processing.
But it's not a whole lot of time
to
make a cognitive decision about i
t.
And what's interesting in thi
s case, is that
you also were able to discount t
he largest circle.
So the largest circle of all
of these circles
was actually on the left side, bu
t on average,
you're discounting that, and just
taking
that average statistical property
.
So you were able to do this stat
istical calculation.
But what if I asked you, was thi
s
particular circle in the display
?
[audience laughing]
So this is motivating my questio
n.
Can we perceive statistical
properties
without actually being aware of t
he individual elements
that give rise to the statis
tical properties?
So the example I just gave was a
n average.
For those of you who remember sta
tistics,
that's not the only important pr
operty
when you are looking at an arra
y of things.
Another one is the diversity or t
he variance in them.
So here, instead of looking at si
ze,
I'm looking at color.
So, on one side, and I think this
works
for even those of you who might
be color-blind.
Can anybody tell me the differenc
e
between the right and the left
here?
[audience murmuring]
Yes, exactly, so on the left, th
is is colors drawn
from a low diversity circle on th
e color wheel.
So only sampling from ones from
this area.
Whereas the ones on the right
are drawn from high diversity.
I'm taking them from anywhere on
this color wheel.
And so this is an interesting ty
pe of statistic.
This is looking at the diversity
of a set of things.
In particular, looking at the di
versity in color.
This type of display can also be
used for me to figure out
what kind of details do people no
tice.
So I can then ask, are people awa
re of
any individual element in these
types of displays?
Or are you aware of the statistic
s
of this ensemble of dots for exa
mple.
And it's hard to do this with sha
pes like this.
So I can do one thing that makes
it easy
for me to figure out what specifi
c details
you know about each individual e
lement.
And that's to translate them
into letters.
I can ask you both then, abou
t the colors,
and about the identity of a p
articular letter.
I can ask you what letter was at
that particular position,
while also having you pay attent
ion to whether or not
the color of the display on the
whole, came from
a high diversity or low dive
rsity color space.
So this question, just to reit
erate, do you perceive
ensembles without perceiving the
individual elements?
How this type of study worked
was that I would
cue people beforehand, to pay
attention to
a particular row that was going
to be displayed.
And so even though I'm gonna be p
resenting a lot of letters,
your attention is gonna be limit
ed
to a particular part of the disp
lay.
Then I'll show the display, this
is 300 milliseconds.
This is plenty of time to become
aware of things.
Remember from the beginning, at
that point
you know your car has crashed, a
nd so it's fast,
but you can still do a lot of p
rocessing
with that type of presentation s
peed.
Then after a blank interval, I wi
ll ask you about
a particular letter, at a par
ticular place.
So you tell me what appeared rig
ht there.
And then I can ask you what was
the color diversity.
Was it high or low?
And I can ask you that about
the row that you
were paying attention to, or to
the rows
that you weren't paying attention
to.
First, letter recall, how good a
re people
at this type of task?
So here, I'm plotting accuracy.
Here, chance is I think about 12
%.
So, how good were people?
And this is when they're either a
ttending to the color
of that row, or attending to the
color of the non-cued rows.
So, does splitting your attentio
n for the color task
hurt your ability to tell me what
a particular letter was?
And it does not.
People are fantastic at this task
.
You guys will be surprised, I wil
l show you
what this looks like in a little
bit.
But people are very good at ide
ntifying letters,
even when these displays are
presented
for just 300 milliseconds.
And splitting your attention be
tween
the two different types of rows.
Either the cue, or non, does
n't hurt your performance.
What about color diversity?
Here chance is 50%, because it c
an either
be high or low if you're guessin
g.
Again, people are very good a
t this task.
And it doesn't matter if they're
paying attention
to the color diversity of the cu
ed row or the non-cued row.
They're just as good at either
of those.
So overall, we're back to this st
ory, of looking
at whether or not people are doin
g these tasks.
Because they are aware of every s
ingle element.
Or if they are aware of just the
ensemble
without the elements.
Both of these theories have p
redictions
about how good you should be
at letter recall and color divers
ity.
So if you're aware of all of the
elements,
obviously you're gonna be good
at recalling letters.
If you're aware of the ensemb
le without the elements,
you still have some access to s
ome detail, otherwise
we wouldn't be able to read, or r
ecognize people.
So both of these predict that you
should be good at
both of these, at the letter r
ecall.
You can do the color diversity
task either by having
an ensemble, statistical processi
ng going on,
or because you're processing ever
y single element,
and then doing the computation
that gives you the ability
to say whether or not it was high
or low diversity.
So again, both of these don't
make any different
distinguishing between these
two theories,
based on this result alone.
What I needed was some way to dis
tinguish these.
And particularly, I wanted to see
whether or not
people notice changes to the ele
ments.
So if you are aware of everythin
g,
if I change anything, you should
be aware of that.
You should notice that.
And so that theory predicts t
hat you would
be able to notice changes to the
elements.
However, if you are aware of an
ensemble
without perceiving each element,
you may not notice
changes to any or all of the ele
ments.
As long as the statistical proper
ties remain the same.
So, to manipulate that,
I'm gonna show you what this disp
lay actually looked like.
So here, just so that people had
enough time to see
what the colors were, the di
splay starts with
these zero figures before switch
ing to numbers.
And so this is what an actual
, several trials
of this looked like for particip
ants.
[audience murmuring]
All right, so it's pretty surpris
ing,
but people were very good at thi
s.
Was there anything else anybody n
oticed
about these displays, besides ju
st that it seems
like a very difficult kind of ex
periment?
- Woman: The second one changed
colors.
- All right, they all changed co
lors, actually.
So, the cued row didn't, but ev
ery other element
in this display changed color
on every single trial that you j
ust saw.
And so maybe some of you are s
aying,
"Well come on, that was super fa
st.
"There's no way anybody woul
d've noticed those,
"even in principle."
So I'm gonna show you it again,
with a particular type of instru
ction.
So, what will help you to see
that these are not completely uno
bvious changes,
is if you pay attention to a su
bset of this display.
So, I want you to try as best
as you can,
to pay attention to both of thos
e positions.
Because then, regardless of what
I cue,
one of them will be changing, oka
y?
So you got that?
So pay attention to the letter
s that will appear
at both of those positions.
All right, so hopefully, you were
able to notice them
much better then you were the fir
st time.
It's still tricky, it's not the
most obvious change
in the world, but the idea is,
if you are perceiving
every single one of these element
s,
you should be able to notice at
least one
of these changes, across the
experiment.
And so I did two experiments
with this.
And they're fairly small in natur
e.
But nobody of the 12 observer
s, in either of these,
noticed any of these changes.
And if you actually do the mat
h on this,
there's 18 letters that were chan
ging on every trial.
There was a 192 trials in which
there was a change.
And that means, there was 3,456
possible changes
for you to notice.
So, that nobody noticed any of t
hese,
really starts to lend support
that you are perceiving
the color of these displays,
the color diversity of these dis
plays,
without perceiving the indivi
dual elements.
So this really supports this idea
that we have this sophisticated
statistical processing
that's going on, even when we are
n't aware of it at all.
So why does it seem that we see
so much richness
based on the other types of failu
res of awareness?
Well, it could be that we are aw
are
of these types of statistica
l properties.
We're aware of averages.
We're aware of variants.
And we're not actually proces
sing consciously
all the individual details at any
given time.
And so this gives an account of w
hy it seems like
the world is rich, while we c
an still miss
critical details in the environme
nt.
So finally, I wanna end with a fu
n, smaller experiment.
Trying to see how our conscious
experience can be altered.
And what type of information can
alter
what our experience is.
And particularly asking this qu
estion, of whether or not
our awareness can be altered
by information
that we aren't aware of at all.
So I showed that we aren't a
ware of a lot.
But what kind of functional role
does that play
in governing our moment to m
oment experience?
So there's particular exampl
es that I'm sure
you guys have had a lot of expos
ure to,
even if you don't study visi
on like I do.
And particularly these types of i
mages, ambiguous images.
This one's called a Necker cube.
And what you are probably doing r
ight now,
is paying attention to different
aspects of this cube.
And depending on where your a
ttention is,
you can see it in one of two
interpretations.
You can either see it as goi
ng away from you,
or you can see it as coming tow
ards you.
Sometimes you can do this will
ingly,
but a lot of times, it just seems
kind of random.
It seems like what you're experie
ncing
is just driven by something th
at you
don't have any control over.
You see the alternations betwee
n these two types
of interpretations of this cube,
without having any conscious cont
rol over it.
So this is a famous example that
's used
in a lot of different types of s
tudies.
But there's also examples of
these types
of ambiguous images out in the w
ild.
And one that you may have seen,
it got famous on the internet a l
ittle while ago,
is one that looks like this.
So I think this should work.
So this is a dancer that is ambig
uous in depth.
She is just a silhouette, so you
don't
get any depth information.
And as a result, your brain real
ly doesn't know
which way she's turning.
But, you can't see both interpret
ations,
left or right, turn at any time.
And so your brain makes a decisi
on about what you see.
So how many of you see her go
ing clockwise?
All right.
[audience chuckling]
Counterclockwise?
- Woman: Yeah.
- How about anyone who's seei
ng it flip back and forth?
- Woman: Yep.
- Man; Yeah, I just did.
- All right.
So, most people will see her goin
g clockwise.
That's the predominant way that
this is interpreted.
There's a couple of different re
asons for that.
One is that her foot is angl
ed a little funny.
And one interpretation, I think
counterclockwise,
your brain would just have to dec
ide
you're looking at her foot from
below,
which is a weird way to look at f
eet.
So, it's also dictated by how fas
t she's going.
There's a lot of different things
that you can do to manipulate it
.
But the idea is, this can go bot
h ways.
And so just to make that clear,
for those of you
who weren't able to see her
going both ways.
If I put a cue on her, that h
elps you see her.
So this effectively disambiguate
s her direction.
This takes that ambiguous inform
ation
about her depth, and by putti
ng eyes on her,
makes it so that she has to be go
ing one direction.
So, on the right here, she's
going clockwise.
And hopefully, if you pay attent
ion to her face,
that might help.
And here, she's going counterclo
ckwise.
And what's fun about this one, is
because
clockwise is so strong for a
lot of people,
her body can start to look like
it's doing
some very funny things.
[audience laughing]
And then again, there is this amb
iguous interpretation
in the middle, where it could
go either way.
My question was, can we make yo
u switch?
Your perception of her direction
.
And in particular, even if y
ou're not aware
that we're making you switch.
And so how this worked, was
that I showed you
one version of the disambiguated
figure.
Which, again, tells you that s
he has to be going
one way or the other, by put
ting eyes on her.
Another way to do that, is to pu
t very subtle contour cues
on other parts of her body, in p
articular, her legs.
So for example, here is exac
tly the same frame
from the animation, but it has di
fferent contour cues.
So this one indicates that her
leg has to be facing forward.
The other one indicates that
her leg
has to be facing backwards.
And so by putting these types of
contour information,
it is telling your brain that t
here is a correct
interpretation of an otherwise am
biguous figure.
And so the idea was, can we intro
duce
these types of cues to people?
And have them basically forcibly
, have their perception
of her direction be switched, ev
en when people
don't notice these cues were
there at all.
So, to you guys, it just look
s like a continuous movie,
as it did to the participants in
this experiment,
but of course it can be broken do
wn
into individual movie frames.
And so the idea was, we had peop
le come in and they
had the task of pressing the left
or right arrow key,
to indicate which direction
they thought she was spinning.
And so this was a fairly boring e
xperiment
for subjects who believed they w
ere watching
this spinning dancer for about 45
minutes,
pressing a button, one way or the
other.
Unbeknownst to them, on cert
ain frames of this,
we would introduce one of these
disambiguating contour cues.
We would have a cue, and then the
idea would be
to measure, do people switch, sh
ortly thereafter?
Having seen this, having been pre
sented with this cue,
but not necessarily noticing it
or seeing it.
And so again, because we're in
terested in whether or not
we can make you switch, even if y
ou're not aware of it,
we only included people who said
that they never saw
any of these contour cues.
After the fact, we always talked
to the subjects
about what they think the experi
ment was about,
what their experience was, and s
o anybody
who saw them, we didn't include.
We only included people who said
they had no idea
that there was anything like
that present
at any of that 45 minutes.
So, to measure this, we would ha
ve the whole segment
of the movie broken up into f
rame segments.
We would have a cue presented,
and then we would look
for a switch that happened a
fter the cue.
This could be a fairly short time
period after,
it could be a different point in
the different frames.
We could measure the reaction tim
e there,
after presenting the cue,
or we could look at a much longe
r duration.
The idea was that any time afte
r presenting the cue,
if people are switching, above wh
at they do,
just by baseline, that would mean
that something
that we're presenting, unconsciou
sly to subjects,
is influencing what they see.
So, to make sure that we hav
e captured this,
we can take all the time points
where
a cue was presented, and line the
m up.
And then basically count how many
frames
after that produced a direction
switch.
Does that make sense?
We're basically time-walking the
whole thing
to the presentation of these unco
nscious contour cues.
So, I'm gonna show here the
amount of switching
above a baseline that we measured
for each subject,
because some people unfortunatel
y sat in there
the whole time, and didn't see
it switching direction once.
And so on the X is how much time
passed
after the presentation,
and on the Y is the amount of swi
tching that occurred.
And so what you see is that, in t
he first second or two
after presenting these cues, the
unnoticed contour cues
caused people's perception
of the dancer's direction to swi
tch.
And so this means that even th
ough they didn't notice it,
and they thought their behavior w
as just random,
we were actually causing their be
havior to change.
So can awareness be altered
by information
that you don't even know exists?
Yes, it can.
What you experience can be gover
ned by information
that you had no awareness of wha
tsoever.
And also another thing that's
interesting
about this experiment,
is that the feeling of randomness
that you may have,
just going through your daily day
life,
doesn't necessarily mean that th
ere
isn't systematic processing going
on,
unconsciously, in visual perce
ption.
Your brain was interpreting t
hese cues
in a way that made sense.
It wasn't just randomly having
these direction changes.
It was interpreting them, even t
hough
you weren't aware of it.
So, overall, I hope that I'v
e convinced you
that you don't see as much as yo
u think you see.
And that what you do see can be
much more sophisticated than
you may realize.
And that your awareness, and your
everyday
moment to moment experience of th
e world,
can be governed by information
that you don't even know exists.
So overall, how the world fi
ts into the mind is governed
by this process of becoming awar
e of it in the first place.
And hopefully now, you all have a
little bit more
appreciation for how sophisticate
d
and counterintuitive
and interesting this process is.
Thank you.
[audience applauding]