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.

Lecture 4 - Perceiving What: Part 2 (17:50 min)

Introduction to Psychology

Meet the Instructors