This course will highlight the most interesting experiments within the field of psychology, discussing the implications of those studies for our understanding of the human mind and human behavior. We will explore the brain and some of the cognitive abilities it supports like memory, learning, attention, perception and consciousness. We will examine human development - both in terms of growing up and growing old - and will discuss the manner in which the behavior of others affect our own thoughts and behavior. Finally we will discuss various forms of mental illness and the treatments that are used to help those who suffer from them. The fact of the matter is that humans routinely do amazing things without appreciating how interesting they are. However, we are also routinely influenced by people and events without always being aware of those influences. By the end of this course you will have gained a much better understanding and appreciation of who you are and how you work. And I can guarantee you that you'll learn things that you'll be telling your friends and family about, things that will fundamentally change the way you think of yourself and others. How can you resist that?!
Lecture 4 - Perceiving What: Part 2 (17:50 min)
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Do curso por University of Toronto
Introduction to Psychology
1742 classificações
Na lição
Sensation, Perception, Attention and Awareness
This section is all about the systems our brain uses to get input from the world ... you will be able to recognize what those things around us are and where they are ... and be able to interpret who we are and how we fit.
Conheça os instrutores
Steve JoordensProfessor
Department of Psychology
Okay, so we've got this input from the external world.
We've, you know used figure ground kind of notions.
Grouping things from Gestalt principles. And we have a sense of where, or at
least, what defines specific objects in the real world.
now, we want to figure out what those objects are.
what do we do now? Let's see.
All right. So I, I decided to here we are.
Sorry. Perceiving what, number two, week three,
lecture four. I, I threw on this, annoying there are,
there are some annoying figures like this.
They're called possible objects. And when you look at it, you know, it
looks possible enough until you start really kind of thinking it through and,
and you realize, well, wait a minute. This line can't go behind that line and,
and, it kind of annoys you a little bit, 'cuz it looks good but ultimately it, it
doesn't pass the test, when you look at it in detail.
so you know, this just kind of shows some of the complexities that our perceptual
systems have to deal with. Alright, so let's jump in.
Here's a scene. depending on how clean you keep your
place, it may be a good or poor representation of a table in your
household. But if we just look at this quickly wow.
Look at all the objects, okay? So, you know?
We, we use all those principles, you know?
Grouping, for example. Similarity.
We kind of think, okay. This must be an object of, of some sort
trying to find something like good continuation.
well, you know? Even though we can't see all of this
object I guess, it kind of disappears behind some things.
We assume it continues on behind there. even this vase here, for example, we've
only got a bit of that. But, but our perceptual system kind of
fills in that this isn't really just a part of a vase, it's, it's probably a
real full vase. similar with this one, actually, which is
occluded by that. So we have all the systems kind of the
same. Okay.
There's objects. Wow.
There's objects all over the place. There's an object.
There's an object. And so let me point to some objects.
What's this? What's this?
What's this down here? What's this?
What's this? Ooh.
I'm not really sure what that is. but this one, for example, is a Buddha.
And we can look at that and see, quite obviously, yeah, that's, that's a Buddha.
How do we do that? In fact, you know, when we look at a
scene like this, what we see is objects. We don't really see shades of light and,
and lines separating x from y. We see this bunch of [UNKNOWN], look over
here, holy crow. What a bunch of stuffed toys, stuffed
into one. And yet we could still go, okay, there's
a lion. There's a little doggie.
There's a bear. This looks like an elephant.
so, you know, we can still see objects of a sort.
And we do this really effortlessly. It just comes to us this way.
which is really cool, really powerful and something we really don't appreciate
until we encounter some people who can't do it that fluently.
and then we really appreciate the ability that our brain has to just do this so
effortlessly, show us objects. Now obviously past experience is playing
a role here. I mean, this is memory.
There's some perceptual thing that hits our eyes, and somehow that makes
connection to previous experiences we've had.
So, we've learned for example, that this thing is called a ukelele.
I think it's a ukelele. that's four strings.
That's what I'd really want to know to know it's a ukelele.
But you know, somewhere, we've seen, for example, ukuleles.
And somewhere in our mind, there exists the concept of a ukulele.
And when we see it, we connect with that concept and we recognize what's there,
and we do this really quickly. How do we do that?
Well, one of the challenges as people have figured thought about this issue Is
something called featural variation. So, imagine the concept of a chair.
And here I've got six chairs depicted for you.
What defines something as a chair? You know, these two might be more like
our prototypical chairs. If somebody asked us to define a chair,
we'd probably say something like, well it has a seat, it has a back, and has four
legs, and you sit on it. you know, that kind of fits that.
But look at this thing. I mean I guess it has a seat and a back.
it certainly doesn't have four legs. this yeah, I guess.
How many legs does this have? I guess you could call it four.
This is a pedestal. This is kind of one leg.
this doesn't re-, I mean it kind of has a back, but it has more wings, so there are
all these other features floating around here that are perhaps not necessary for a
chair. So, how can we recognize all of these
things as chairs? Or how can we, this, this is a little
bit, okay, it's not subliminal. I was going to say subliminally Influence
here, but it's pretty obvious. but nonetheless.
How can we recognize all those? Look at the Ss, for example.
They're quite different in these different fonts.
This one's got these little tails and such.
So, we can't just say an S is a squiggly line.
Sometimes it is just a squiggly line. Sometimes it's a real fat with barely any
squiggle. This one's, like, all kind of crunched
out, and what the heck's this one down here?
you know, you see that there's a lot of variability.
And yet our perceptual system is very good at handling that variability.
How does it do it? What's it doing?
well, I'm not going to pretend we know 100%.
In fact, that's one of the cool things about psychology being such a young
science. There are still many questions that we're
trying to find really good answers for. but in this case I think we kind of have
an idea, and we've went through some ideas.
So, there'll be something called template theory that I won't discuss, but it'll be
featured in one of the videos I point you to at the end.
I'm going to move towards prototype theory and this notion of fuzzy
prototypes because this is what we really think is happening now.
Now, we're going to get a little abstract.
I'm going to bring you into the research world.
In the research world, of course, we don't use things like chairs.
we want to create new concepts ourselves, and we often want to use relatively
abstract things that don't have too much baggage associated with them.
So, here's an example of how people study this in a lab.
They will create what's called a prototype.
Nothing really special about the prototype to start with.
It's just some, in this case, configuration of dots.
But then what we do is we create slight distortions of this prototype.
So, think of this as your average chair. You know, the, the, if you took every
chair in the world and average them together, you'd have some prototypical
chair. But now any specific chair, is not
exactly this chair. Slight little features are changed a
little. So in these distortions we take some of
these dots and move them a little bit and for each distortion we move different
dots different ways. And so we end up with these, what are
called exemplars. And, and just worry about the left side
of this screen for now, just over here. We end up with these exemplars.
So, there's been a number of experiments that have been done with these exemplars.
One I'll tell you about is, if you show people exemplars that were derived from a
prototype like this, versus others that were not.
they still have dots but they were not derived from the prototype.
They're not all similar to a common prototype.
And now, if you ask people, which belongs to which set?
You just kind of say, you know. Some of these are kind of like a family,
and some are not. So, decide whether specific ones are in
the family or not. People can recognize the family.
They don't know what it is that defines the family.
But they can recognize these exemplars that were based on a prototype, and
discriminate them from ones that were not.
So, something is getting through as they see these things, they are kind of
learning the average prototype that they were all derived from.
And they're kind of seeing that resemblance on some very low level.
In fact, if in one of these memory studies, you actually present the
prototype, even if you never presented it during a study.
So, you never showed it to them until you're saying, hey, is this one of the
family? People will very strongly endorse the
prototype. They'll say, oh, yeah absolutely, that's
one of the family. even though they never saw it before.
So, the point of all this is, kind of, as you're viewing all these different
chairs, there is an average chair kind of being formed in your mind.
And an average bird, and an average table.
In an average female, in an average male, in an average any concept that you can
think of. Microphone.
computer. Sneaker.
You know, I could go on and on and on. Take any object in the world.
Any, any concept even, like a relationship.
An average relationship. What does that look like?
Any concept you can think of, as you experience these exemplars through life.
so as you see each different dog, let's say, you are gradually building up in
your mind the average dog. 'Kay.
Some concept of the average dog. And we call that the prototype.
so other studies who have, that have now done this same kind of thing, they've
established a prototype by showing exemplars.
And then if they just say, hey, is this part of the same concept as the prototype
or not? what they've shown is that the more
similar so this is a low distance. Its quite similar to the prototype this
is a high distance thats kind of portrayed over here how far away it is
from the prototype. If you present these and, and you just
ask people to make a quick decision member of the same family or not.
But as quickly as you can. The more similar an item is to the
prototype, the quicker people are. so for example, imagine instead of this
abstract world, we had birds. And we had some notion of the average
bird. Now if you showed people pictures, and
you said sometimes it's going to be a bird, sometimes it's not.
And I want you to decide as quickly as you can bird or not okay.
And you're making bird or not decisions. If I show you something like a, a robin
or a crow or a sparrow you're going to probably be very quick.
Because those birds are probably very similar to your prototypical bird.
But if I showed you a penguin or a rooster or something like that something
thats not really or an ostrich something that's not really your typical bird.
You find that people take a lot longer to say yes, that's a bird.
And so the notion we have is that when you see objects in the real world.
Let me just go back, when you see objects in the real world like this.
Every time you look and attend to an object, right over here let's say you
figure out what that object is. You attend to it and it's being matched
to all these photo types in a sort of fuzzy way.
And whichever one it's closest to, that's what springs into your perception.
That's what you see it as. So, you know, for example even if we go
back to our friend ukelele here, it's kind of guitar like.
so it's got a lot of features that are very similar to a guitar.
So, it would be similar to both the guitar prototype and the ukulele
prototype. But it would be more similar to the
ukulele prototype simply because of its size, and, you know, I highlighted the
four strings. If I saw four strings on this, I would
really say ukulele. If I saw six, I would be like, hmm could
be a very small guitar. you know, that, that's the kind of idea
of how you could refine the perception of something afterwards.
But, like this, that's a purse, this is a vase, that's a television.
This is probably a VCR, no, this looks like a VCR, this is probably a TV.
cable box, you know. and so literally, as we look around, it's
just like what do I have in memory that's very similar to that.
This is an almost beautifully prototypical lamp, so we had a really
easy time, figuring out what that is. If we go back to this one, where I said
what the heck is that, y'know, I now think it's kind of like a chest.
And it's sort of a prototypical chest but it's kind of weird too.
You get the idea. That's how we think it works.
alright, so what about when things go wrong with this step, the mapping the
features to some memory representation? Well, I've already told you one
situation, the man who mistook his wife for a hat.
that thing that we call visual agnosia. Remember, the glove, where somebody could
see a glove perfectly well, but they could not recognize it as a glove.
And that's what happens when this part of the process, a part that we know is
associated with association cortex, right.
When that part of the process goes wrong, you get things like that.
Where they can see perfectly fine, but they can't recognize what they're seeing.
I wanted to tell you about another kind of funny version of that.
Or, funny, funny. I don't know.
It's not funny if you have it, I guess. It's an interesting version.
There's something called prosopagnosia. so this is me, and this is somebody I'm
very, very often confused with, Johnny Depp.
You know, we're so similar, in so many ways.
Sorry, I have to have a little bit of fun doing this, right?
but, but I want to kind of be semi-serious, because I did happen to
pick pictures where in some ways at least we have a resemblance.
If my sister suffered from prosopagnosia, which is caused by damage to a very
specific part of the brain called the fusiform gyrus, if you're interested, go
check it out. but that part of the brain seems to be
the part we use to bring things together into a gestalt, into a whole.
so, and the face is very, you know, if you look at eyes there's nothing
particularly distinguishing about a person's eyes.
Or nose. Or mouth.
What defines a person is the way it all comes together to form a specific face.
When somebody has prosopagnosia, they lose that ability to bring everything
together, and they lose the ability to recognize faces.
They can still feel the familiarity, but they can't recognize the face, a very
specific kind of recognition, visual recognition deficit.
So, if my sister had this disorder and let's say I went and stood at the foot of
her bed but then was perfectly still. I didn't say anything and I didn't move,
because my speech or my movements she might recognize.
But if I just gave her my visual look and she saw me at the end of the bed.
She might say something like the following.
Know that guy there. He's very familiar.
I know who he is. He could be my brother, or he could be a
movie star. I, you know, to her, it's the same thing.
I am the same as Johnny Depp to my sister that sounds nice, right?
but that's, they lose the ability to recognize the identity.
So, they still get the familiarity, but not the actual recognition.
Another example of how critical that recognition process is.
all right. So, some follow-up things that you
want to check out, 'cuz I think they're kind of cool.
there's a video of somebody with visual agnosia, again, just to give you a nice
concrete sense of what that's like. and, and this person will describe you
know, when he looks around, he sees colors and shapes, but he doesn't see
objects. He doesn't recognize what he's seeing.
so, a, a real powerful presentation of that.
Similarly, a presentation of somebody with prosopagnosia, what I was just
talking about, the lack of an ability to recognize faces.
I threw this one in because it's just a head-scratcher.
It's a really fascinating opposite of prosopagnosia, just to show you how
complex visual perception can be. People with Capgras delusions.
They can recognize people, but the people they recognize don't feel properly
familiar. So, there will be people who say, you
know, that person over there looks like my spouse.
They talk like my spouse, they act like my spouse, but they don't feel right to
me. They're not my spouse.
And they will begin to feel like this person's an intruder.
That either they're a robot that's been made to look like their spouse, or
they're an alien that's somehow taken over their spouse's body.
People with Capgras delusions have been known to kill spouses and cut off their
heads to prove to other people that they are a robot or they are an alien.
They're that convinced that there's something not right about the person.
So, check that out, it's kind of freaky weird all right.
And I've put in a less freaky weird, more mundane, but theoretically relevant video
that talks about this template versus prototype theory.
in case any of that was at all confusing this should bring it up.
And then we got a reading about visual object recognition in general.
so check those out and also keep in mind of course when we're doing this.
That everything I'm telling you about visual recognition is true of every sense
that we think of. So, for auditory you know being able to
recognize that as you're spouses voice or your brother voice.
Or being able to recognize a particular singer or a particular sound.
of a you know different guitars for example sound different to a trained ear
that can hear that. so all of this recognition holds for
every sensory ability we have. I'm just focusing on vision to follow one
through okay? That's all I'm going to talk about what.
Next lecture we're going to talk a little bit about another critical thing, which
is where the stimulation is coming from. Alright?
That'll be next.
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