- Welcome everyone to Wednesday Nite @ the Lab.
I'm Tom Zinnen, I work here at the
UW-Madison Biotechnology Center.
I also work for the Division of Extension.
And on behalf of those folks, and our other co-organizers,
Wisconsin Public Television,
the Wisconsin Alumni Association,
and the UW-Madison Science Alliance,
thanks again for coming to Wednesday Nite @ the Lab.
We do this every Wednesday night, 50 times a year.
Tonight it's my pleasure to introduce to you Emily Ward.
She's an assistant professor in
the Department of Psychology here.
She was born in Santa Cruz, California.
And went to high school at-- excuse me,
at Pacific Collegiate School in Santa Cruz.
And then she did her undergraduate degree
in neuroscience
at Franklin & Marshall in Lancaster, Pennsylvania.
Then she went to Yale, to get her master's
and her PhD in psychology.
Then she did a postdoc at the Donders Institute
in Nijmegen, in the Netherlands.
And then she came to the UW-Madison 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 Wednesday 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 part of this series.
And I'm excited to talk about some of my research.
So, as a psychologist, I'm interested in the mind.
And in particular, I'm interested in
the relationship between the mind and the world.
How does everything that's out here, get into the mind?
And the first step in understanding
the relationship between the mind and the world,
is understanding how we become
aware of the world to begin with.
This may seem very straightforward,
after all, we walk around every day,
seeing things, noticing things.
So this may seem like a weird type of topic to study.
But what I hope to show in this talk,
is that this relationship between the mind and the world,
is governed by our awareness.
And that what we become aware of, is not
as straightforward, and can be very counterintuitive,
and interesting in many ways that you might not
ordinarily think about.
So, to motivate my research, I want to present an example
that I hope not too many of you have experienced,
to give you a sense of how there is a disassociation
between what goes on in the world, 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 concrete.
This is a timeline of what went on, in that previous film.
At zero milliseconds, the external object hits the car.
The events unfold, such that at about 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 continues to deflate
and the occupant moves back to the 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 picture,
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 spectacular 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 things.
The first is that you don't see
as much as you think you see.
The second is that what you do see, can be
surprisingly sophisticated, and counterintuitive.
And finally, I'll end with something a little fun,
talking about how your awareness can be altered
by information that you don't even know
exists in the first place.
So a car crash is a little grim to start out a talk with.
So I'd like to give another example,
[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 video.
[lively piano music]
- Clearly, somebody in this room, murdered Lord Smythe.
Who, at precisely 3:34 this afternoon, was brutally
bludgeoned to death with a blunt instrument.
I want each of you to tell me your whereabouts
at precisely the time that this dastardly deed took place.
- I was polishing the brass in the master bedroom.
- I was buttering his lordship's scones belowstairs, sir.
- Why, I was planting my petunias, in the potting shed.
- Constable, arrest Lady Smythe.
- But, but how did you know?
- Madame, as any horticulturist will 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 observant 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 afternoon, was brutally
bludgeoned to death with a blunt instrument.
I want each of you to tell me your whereabouts
at precisely the time that this dastardly deed took place.
- I was polishing the brass in the master bedroom.
- I was buttering his lordship's scones belowstairs, sir.
- Why, I was planting my petunias, in the potting shed.
- Constable, arrest Lady Smythe.
[audience chuckling]
- So, obviously, I'm giving a talk about visual awareness.
And I'm sure some of you were a little skeptical
that this would be a straightforward movie,
and were looking for particular changes.
But even if you did notice some of 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 changing.
There is nothing very small about these types of changes.
And so what happened here, was that you collectively
experienced what I'm going to call a failure of awareness.
This is failing to notice something that's otherwise
pretty noticeable in the environment,
if you were paying attention to it.
And some of you are probably familiar
with some of the most famous cases of this.
Whenever you're talking about failures of awareness,
most people out in the world, probably most people
in this audience, most incoming psychology students,
are aware of a particular example,
which is more commonly known as the 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 basketball.
And you as a participant, would be paying attention
to a subset of the number of players.
So, for example, you might be paying attention to
how often the white players pass the ball back and forth.
Meanwhile, in the middle of your task,
which is pretty difficult, keeping track
of the basketball, with only the subset
of these players in white T-shirts,
a man in a gorilla suit walks through
the middle of the display.
Most people don't notice this the first time they see it.
If you guys are familiar with this, and this is why
I don't use this, is you do see it.
Once you're aware of it, you have an expectation
about what's gonna happen, and 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 question
about what the nature of this deficit actually is.
Is it in fact, a type of blindness, as the name suggests?
Meaning that this is a failure of perception.
That you really just don't see that gorilla,
as it passes through the basketball game.
Or is it something a little bit different?
Is it a failure of your memory?
And what I mean by failure of memory,
isn't just that you forget
where you put your keys in the morning.
It's something a little bit more subtle.
And so to give you an idea of what exactly I mean
by failure of memory, I'm going to have you watch
another little video.
In this video, this is what's known as
a rapid serial visual presentation display.
RSVP for short, that's not important, what is important
is you're gonna see a bunch of letters.
They're gonna be presented very quickly
at the center of the screen.
And I just want you to pay attention
to them as best you can.
All right.
Can anybody tell me exactly which letters you saw, in order?
[audience murmuring]
You can't, right.
I can't, I've seen this a lot, and I still can't.
But you wouldn't say you didn't see them, in the moment.
If it was anything like my impression,
it's that you have this fleeting sense
of what you see, and then it's gone.
So that's what I mean by a failure of memory.
That simply because you can't tell me what you saw
after the fact, doesn't mean
you didn't see it in the first place.
Let me contrast that with the typical story about
inattentional blindness.
Where I'm looking specifically at
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 expectation 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 test whether or not
you really saw a particular letter, I would tell you
to beforehand, clap if you saw the letter M.
Or the letter A, I think is my example here.
So if I give you that instruction, to clap
when you see an A, you then expect 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 out whether or not
you failed to see, or saw a particular 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 unusual,
you would then expect something unusual.
And in that case, you can report whether or not
you saw something unusual, like a gorilla, for example.
But because you were expecting it,
that would rule out the effect to begin with.
So the very thing that I'm interested in measuring,
just by telling you that it might happen,
undermines inattentional blindness.
And so you can see that getting around this,
experimentally, is a little tricky.
How do you figure out if people
are really blind to a gorilla,
or if they're just failing to report in the same way
that you all failed to report the stream of letters.
So, just to highlight, disentangling this idea
that this effect might be a failure to see,
or just a failure to remember,
is a bit of a catch-22.
And I think I might have a way around this.
And so I'm gonna tell you about a minor change
that I made this logic, to see if 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 report,
and having you have no expectation,
I wanted to see if I can manipulate your expectation.
So instead of having no expectation whatsoever,
I wanted to have you expect something unusual.
But expect only a very particular type
of unusual event.
And this, I hoped, would be something that would allow me
to see whether or not people could report
the presence of something unusual, but maybe would
still fail to see something that violated that expectation.
So, because these types of experiments are very famous,
and I can't show people gorillas
out in the wild for example,
we use a different type of display.
And so again we're using simple letters in this.
And I'll give you a sense of what this looks like.
But what we show participants in these types of studies
is a computer display where there'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 randomly on the display.
And subject's task is to count how many times
a subset of them, so in this example 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 shot, I'll show you
what a typical trial looks like.
Any numbers?
- Audience: Five.
- All right, you guys are doing great.
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 inattentional blindness,
I am allowing you guys to know
that something might have happened.
Nothing happened on this one,
but when I showed this to subjects in the lab,
I had another trial, which is similar,
except now, something slightly different occurred.
How many of you noticed that there was a gray cross
that went along the middle of the screen?
And how many of you noticed the gorilla?
[audience laughing]
All right, so hopefully for some of you,
you still may have missed that cross.
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 paying attention,
so I'm not trying to trick you
by having it appear in some peripheral location.
This is the type of unexpected event
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 being presented.
And so that gets them used to the task.
And then on the fourth trial, a red cross appeared in this.
And so it looked something like this.
This is a typical way of studying
inattentional blindness.
And what you then would ask is,
"Did you notice anything different?"
And then ask specifically,
"Did you notice if a red cross appeared?"
And if a participant said that they
didn't notice anything, and they didn't notice a red cross,
I would categorize this as them being
inattentionally blind in this case.
Typically, about 50% or 60% of people
miss this type of cross.
Previous experiments have stopped here.
But I decided to keep going.
And I gave people the instruction
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 instruction
to immediately report what they see in the moment.
Then I continued on with the trial structure.
There was a few more trials where 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 unusual.
But that unusual event was the presence of a red cross.
Importantly, at the very last trial,
it was a critical trial,
where half of the subjects saw a new event.
In this case, it was a blue E, moving
the opposite direction on the screen.
Or just another instance of the red cross
moving across the screen.
And the question is, if people are presented
with something that violates their expectation
about what's going to occur,
do more people miss this new, unexpected 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 the repeated one?
So first of all, I measured
how many people missed this repeated event.
A few people, while they were doing the counting task,
did miss it, but it's not very many.
Critically, almost five times the amount of people
missed this new unexpected event.
So this means that more people are 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 inattentional 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 reflects the limitation
of perception, and not of your memory.
So this has implications for the real world.
This means that if you are driving 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 see these letters
that I presented earlier, and forgot.
It's truly reflecting a limitation of your perception
because your attention is otherwise 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 see so much,
when I demonstrated just now that 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 beforehand,
but also if you don't know what's going on beforehand.
And it also just strikes you as really rich.
You see a lot of detail.
You see exactly what's going on.
These pictures seem evocative.
They seem beautiful, they seem interesting.
And you can do all this, even though
this is presented very quickly.
So this is in contrast to what I just showed you,
where we can be really bad at seeing
noticeable events or changes out in the world.
But we also feel like we're really good
at noticing rich detail.
How do we reconcile these two experiences?
Is it that we have a limited awareness of detail?
But we are instead aware of some statistical properties
of the world, that make our experience seem so rich.
So, I'll unpack that a little bit.
I teach statistics here, so I know when I mention that,
a lot of people's eyes glaze over.
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 really what I mean.
What I'm talking about is,
do we perceive statistical properties?
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 would guess?
- Audience: Left.
- All right, average is a statistical property.
So here, you're doing some computation,
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 left,
has the bigger average size circle.
- 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 lot of processing.
But it's not a whole lot of time to
make a cognitive decision about it.
And what's interesting in this case, is that
you also were able to discount the largest circle.
So the largest circle of all of these circles
was actually on the left side, but on average,
you're discounting that, and just taking
that average statistical property.
So you were able to do this statistical calculation.
But what if I asked you, was this
particular circle in the display?
[audience laughing]
So this is motivating my question.
Can we perceive statistical properties
without actually being aware of the individual elements
that give rise to the statistical properties?
So the example I just gave was an average.
For those of you who remember statistics,
that's not the only important property
when you are looking at an array of things.
Another one is the diversity or the variance in them.
So here, instead of looking at size,
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 difference
between the right and the left here?
[audience murmuring]
Yes, exactly, so on the left, this is colors drawn
from a low diversity circle on the 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 type of statistic.
This is looking at the diversity of a set of things.
In particular, looking at the diversity in color.
This type of display can also be used for me to figure out
what kind of details do people notice.
So I can then ask, are people aware of
any individual element in these types of displays?
Or are you aware of the statistics
of this ensemble of dots for example.
And it's hard to do this with shapes like this.
So I can do one thing that makes it easy
for me to figure out what specific details
you know about each individual element.
And that's to translate them into letters.
I can ask you both then, about the colors,
and about the identity of a particular letter.
I can ask you what letter was at that particular position,
while also having you pay attention to whether or not
the color of the display on the whole, came from
a high diversity or low diversity color space.
So this question, just to reiterate, 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 presenting a lot of letters,
your attention is gonna be limited
to a particular part of the display.
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, and so it's fast,
but you can still do a lot of processing
with that type of presentation speed.
Then after a blank interval, I will ask you about
a particular letter, at a particular place.
So you tell me what appeared right 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 are 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 attending to the color
of that row, or attending to the color of the non-cued rows.
So, does splitting your attention 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 will show you
what this looks like in a little bit.
But people are very good at identifying letters,
even when these displays are presented
for just 300 milliseconds.
And splitting your attention between
the two different types of rows.
Either the cue, or non, doesn't hurt your performance.
What about color diversity?
Here chance is 50%, because it can either
be high or low if you're guessing.
Again, people are very good at this task.
And it doesn't matter if they're paying attention
to the color diversity of the cued row or the non-cued row.
They're just as good at either of those.
So overall, we're back to this story, of looking
at whether or not people are doing these tasks.
Because they are aware of every single element.
Or if they are aware of just the ensemble
without the elements.
Both of these theories have predictions
about how good you should be
at letter recall and color diversity.
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 ensemble without the elements,
you still have some access to some detail, otherwise
we wouldn't be able to read, or recognize people.
So both of these predict that you should be good at
both of these, at the letter recall.
You can do the color diversity task either by having
an ensemble, statistical processing going on,
or because you're processing every 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 distinguish these.
And particularly, I wanted to see whether or not
people notice changes to the elements.
So if you are aware of everything,
if I change anything, you should be aware of that.
You should notice that.
And so that theory predicts that 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 elements.
As long as the statistical properties remain the same.
So, to manipulate that,
I'm gonna show you what this display actually looked like.
So here, just so that people had enough time to see
what the colors were, the display starts with
these zero figures before switching to numbers.
And so this is what an actual, several trials
of this looked like for participants.
[audience murmuring]
All right, so it's pretty surprising,
but people were very good at this.
Was there anything else anybody noticed
about these displays, besides just that it seems
like a very difficult kind of experiment?
- Woman: The second one changed colors.
- All right, they all changed colors, actually.
So, the cued row didn't, but every other element
in this display changed color
on every single trial that you just saw.
And so maybe some of you are saying,
"Well come on, that was super fast.
"There's no way anybody would've noticed those,
"even in principle."
So I'm gonna show you it again,
with a particular type of instruction.
So, what will help you to see
that these are not completely unobvious changes,
is if you pay attention to a subset of this display.
So, I want you to try as best as you can,
to pay attention to both of those positions.
Because then, regardless of what I cue,
one of them will be changing, okay?
So you got that?
So pay attention to the letters that will appear
at both of those positions.
All right, so hopefully, you were able to notice them
much better then you were the first 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 elements,
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 nature.
But nobody of the 12 observers, in either of these,
noticed any of these changes.
And if you actually do the math on this,
there's 18 letters that were changing 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 these,
really starts to lend support that you are perceiving
the color of these displays,
the color diversity of these displays,
without perceiving the individual elements.
So this really supports this idea
that we have this sophisticated statistical processing
that's going on, even when we aren't aware of it at all.
So why does it seem that we see so much richness
based on the other types of failures of awareness?
Well, it could be that we are aware
of these types of statistical properties.
We're aware of averages.
We're aware of variants.
And we're not actually processing consciously
all the individual details at any given time.
And so this gives an account of why it seems like
the world is rich, while we can still miss
critical details in the environment.
So finally, I wanna end with a fun, 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 question, 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 aware of a lot.
But what kind of functional role does that play
in governing our moment to moment experience?
So there's particular examples that I'm sure
you guys have had a lot of exposure to,
even if you don't study vision like I do.
And particularly these types of images, ambiguous images.
This one's called a Necker cube.
And what you are probably doing right now,
is paying attention to different aspects of this cube.
And depending on where your attention is,
you can see it in one of two interpretations.
You can either see it as going away from you,
or you can see it as coming towards you.
Sometimes you can do this willingly,
but a lot of times, it just seems kind of random.
It seems like what you're experiencing
is just driven by something that you
don't have any control over.
You see the alternations between these two types
of interpretations of this cube,
without having any conscious control over it.
So this is a famous example that's used
in a lot of different types of studies.
But there's also examples of these types
of ambiguous images out in the wild.
And one that you may have seen,
it got famous on the internet a little while ago,
is one that looks like this.
So I think this should work.
So this is a dancer that is ambiguous in depth.
She is just a silhouette, so you don't
get any depth information.
And as a result, your brain really doesn't know
which way she's turning.
But, you can't see both interpretations,
left or right, turn at any time.
And so your brain makes a decision about what you see.
So how many of you see her going clockwise?
All right.
[audience chuckling]
Counterclockwise?
- Woman: Yeah.
- How about anyone who's seeing it flip back and forth?
- Woman: Yep.
- Man; Yeah, I just did.
- All right.
So, most people will see her going clockwise.
That's the predominant way that this is interpreted.
There's a couple of different reasons for that.
One is that her foot is angled a little funny.
And one interpretation, I think counterclockwise,
your brain would just have to decide
you're looking at her foot from below,
which is a weird way to look at feet.
So, it's also dictated by how fast she's going.
There's a lot of different things
that you can do to manipulate it.
But the idea is, this can go both 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 helps you see her.
So this effectively disambiguates her direction.
This takes that ambiguous information
about her depth, and by putting eyes on her,
makes it so that she has to be going one direction.
So, on the right here, she's going clockwise.
And hopefully, if you pay attention to her face,
that might help.
And here, she's going counterclockwise.
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 ambiguous interpretation
in the middle, where it could go either way.
My question was, can we make you switch?
Your perception of her direction.
And in particular, even if you'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 she has to be going
one way or the other, by putting eyes on her.
Another way to do that, is to put very subtle contour cues
on other parts of her body, in particular, her legs.
So for example, here is exactly the same frame
from the animation, but it has different 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 there is a correct
interpretation of an otherwise ambiguous figure.
And so the idea was, can we introduce
these types of cues to people?
And have them basically forcibly, have their perception
of her direction be switched, even when people
don't notice these cues were there at all.
So, to you guys, it just looks like a continuous movie,
as it did to the participants in this experiment,
but of course it can be broken down
into individual movie frames.
And so the idea was, we had people 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 experiment
for subjects who believed they were watching
this spinning dancer for about 45 minutes,
pressing a button, one way or the other.
Unbeknownst to them, on certain 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, shortly thereafter?
Having seen this, having been presented with this cue,
but not necessarily noticing it or seeing it.
And so again, because we're interested in whether or not
we can make you switch, even if you'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 experiment was about,
what their experience was, and so 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 have the whole segment
of the movie broken up into frame segments.
We would have a cue presented, and then we would look
for a switch that happened after 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 time there,
after presenting the cue,
or we could look at a much longer duration.
The idea was that any time after presenting the cue,
if people are switching, above what they do,
just by baseline, that would mean that something
that we're presenting, unconsciously to subjects,
is influencing what they see.
So, to make sure that we have captured this,
we can take all the time points where
a cue was presented, and line them 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 unconscious contour cues.
So, I'm gonna show here the amount of switching
above a baseline that we measured for each subject,
because some people unfortunately 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 switching that occurred.
And so what you see is that, in the first second or two
after presenting these cues, the unnoticed contour cues
caused people's perception
of the dancer's direction to switch.
And so this means that even though they didn't notice it,
and they thought their behavior was just random,
we were actually causing their behavior to change.
So can awareness be altered by information
that you don't even know exists?
Yes, it can.
What you experience can be governed by information
that you had no awareness of whatsoever.
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 there
isn't systematic processing going on,
unconsciously, in visual perception.
Your brain was interpreting these cues
in a way that made sense.
It wasn't just randomly having these direction changes.
It was interpreting them, even though
you weren't aware of it.
So, overall, I hope that I've convinced you
that you don't see as much as you 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 the world,
can be governed by information
that you don't even know exists.
So overall, how the world fits into the mind is governed
by this process of becoming aware of it in the first place.
And hopefully now, you all have a little bit more
appreciation for how sophisticated
and counterintuitive
and interesting this process is.
Thank you.
[audience applauding]