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 8 - Split Brain (14:40 min)
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From the course by University of Toronto
Introduction to Psychology
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From the lesson
The Matter of the Mind
There was a time when one could study Psychology without linking phenomena back to the brain itself, but those days are slowly disappearing. Now every Psychology student, yourself included, is expected to have at least a general knowledge of brain organization and structure. At the end of this section you will be able to locate structures of the brain and discuss its organization.
Meet the Instructors
Steve JoordensProfessor
Department of Psychology
Alright, now that you guys are all amateur and neuroscientists I wanted to
kind of cap off this week of the brain by telling you about one of at least the
studies that I found most fascinating when I first learned about the brain.
So, I'm trying to position my head perfectly right here to illustrate that
what we're going to be talking about is something called split-brain syndrome.
a situation where the corpus callosum, the area right between the two
hemispheres is severed, is cut down the middle creating both a left brain and a
right brain, that should be on the, left brain and a right brain.
within the same skull. and some of the really fascinating
results you saw from those, experiments and what they tell us about perhaps the
biggest question we have as psychologists, human consciousness.
Here we go. Alright, so week two lecture eight, the
last lecture of week two. and yeah, it's all about the brain but
it, what I really want to do is bring together a lot of the things that we've
been talking about. So I have emphasized a few times this
structure between the two hemispheres. It's not the only place the two
hemispheres join. But it is certainly the, the, the super
highway of information, the, the part of the two brains.
That the two hemispheres that connects the two and allows information to flow
freely between them. Now, why would anybody have their corpus
callosum cut? Well in virtually every case, the
patients who did this had suffered from extreme forms of epilepsy.
Now in case you don't know much about epilepsy, comes in different forms.
Some are called Petit mal seizure. People have seizures.
But in the Petit mal case, they the seizures are.
You might not even detect them. So, I could have one right now and I
could just stare into space for a second and then come back and, and that can be a
Petit mal seizure. A little bit of electrical activity in
the brain that kind of freezes me for a moment but literally just for a moment.
but the more dramatic form is, is something called a Grand mal seizure.
Which if you translate, is big bad so the big bad seizures.
And what happens in the big bad seizure is that electrical activity starts in one
side of the brain and then goes over to the other but then gets arced back to the
starting place and eventually forms a feedback loop.
So it goes back and forth and back and forth and back and forth, getting
stronger and stronger as it does so. And eventually it literally short
circuits the brain. Electrical activity starts going all
through the brain. the person normally passes out, but the
electrical activity continues and it stimulates the motor cortex randomly.
and so that leads to convulsions because the motor cortex is being stimulated and
so random muscles are moving. So you see a person on the floor usually
because they're unconscious. But they're body's moving and convulsing,
as we call it as a result of these seizures.
So you know, really horrible thing to have happen to you.
most people state it's very embarrassing to suffer a Grand mal seizure in a public
place But for most people who have epilepsy,
those sorts of Grand mal seizures are relatively infrequent, however for some
people, they're extremely frequent. some people in fact have had as many as
five to ten of these a day and if you're one of those people.
You reach a point where you don't even want to go outside.
You don't want to be around other people. You don't want to be in public because
you have this constant fear of having a seizure and being embarrassed.
And, you know, having to explain to other people and, quite potentially, causing
harm to yourself. If you have a seizure on a hard concrete
floor in the middle of a highway. You know if you are walking across the
screen you suddenly have a seizure it's a very dangerous thing.
So for these kind of students not students, excuse me patients at one point
doctor's started thinking well, if this is cause by feedback loop across the
hemispheres of the brain. If we cut that super highway and did not
allow the hemispheres to speak to one another then we should prevent the
seizures that should eliminate the seizures.
I know it sound pretty dramatic. This is another one of those one way
changes to the brain. You cannot undo this.
But, some patients felt their life was so horrible the way it was that they were
willing to have their corpus callosum severed.
So they went in, they had this procedure and, you know, essentially as you see
here this whole structure was cut, leaving them with two hemispheres that
could no longer communicate well with one another.
So what happened? I mean to some extent you know, surely
this, this was meant to help with their symptoms.
But the doctors that were doing this in the first place and, and these are very
famous people now, Richard Sperry and Michael Gazzaniga.
they were very interested in how this would change the person's being, how it
would change their life. And initially, the answer was very
surprising. It didn't seem to change them very much
at all. They woke up from the seizure and from
all accounts seemed to be the same person that had, that they had seen the day
before the seizure for example. However, over time they noticed some
strange things happening. Sometimes the somebody would be asking
the patients questions. And they would notice that the left hand
of the patient would get agitated while the rest of the patient didn't seem
agitated. Or sometimes the left hand would start
doing things. in one sort of relatively famous case,
the left hand started grabbing nurses. Or hitting nurses or throwing objects
across the room. And when anybody asks the patients, why
are you doing that, they would say things like I don't know.
I didn't meant to do that. I, I have no idea.
so there was this really kind of curious behavior going on.
An so eventually, Sperry and Gazzaniga designed a study.
I'm sorry, this, this was just to show you the severed corsa, Corpus Callosum.
an we went through, why you'd cut it. So here's the study that they, designed.
They would have a bunch of objects in front of one of these patients who had
their corpus callosum cut. And they would now show words, but they,
they would cleverly and this doesn't really do full justice to how they had to
do this, but it, but it's good enough. They would find a way to show the words
in such a way so that only one or the other hemisphere would see them.
So it all had to do with lenses on the eye, each eye is actually divided into a
left and right whatever falls on the right side of one eye goes to the left
hemisphere. Sorry, the right side of both eyes goes
to the right hemisphere, whatever falls to the left side of both eyes goes to the
left hemisphere. So they had these special contact lenses,
and they could present words so that, that word would ultimately, so, for
example, key, would ultimately only be, registered in the left hemisphere.
Whereas ring would only be registered, I'm sorry, I'm getting this wrong.
Key would only be in the right hemisphere.
Ring would only be in the left. So you can, you know, just kind of trust
me on this. You can, you can set up the apparatus so
it would work that way. So now, what we have is hemispheres that
don't speak to each other. And when we present this, this hemisphere
is seeing the word key and this hemisphere is seeing the word ring.
Now if we ask the patient, what word did you see, they will say the word ring.
Okay? Let's think about that.
Why ring? Well, ring is the word that went into the
left hemisphere and of course we know that speech is primarily in the left
hemisphere. This is what broke[INAUDIBLE] areas for
example in the left hemisphere. So the speech hemisphere was seeing the
word ring, and that's what it said out loud, I see a ring.
Now, early on they just did these kinds of studies, and what they noticed is that
the left hand again would be very agitated, almost like the left hand's
like, almost like it's trying to say no. That's wrong, that's not the word.
And, of course, the left hemisphere is seeing the word, sorry the right
hemisphere is seeing the word key over here.
and the right hemisphere controls the left hand.
That's that contralateral wiring I told you about.
So eventually they would lay, they decided to lay objects out and what they
found is if they again asked the question, what did you see?
The left, the right hemisphere which controls the left hand, this left hand
would reach out and choose the object that the right hemisphere saw.
So the person would verbally say, I saw the word ring, but they would reach out
with their left hand for the key. And left hand saying, no I saw the word
key. Really fascinating.
It's suggested to them, that there is almost, essentially two consciousnesses
now, inside this one skull. By splitting the brain in half, it seems
as though the mind has been split. And that there are now two entities
within the same brain, extremely fascinating, and it got even kind of more
fascinating as they tried to mine this more.
At some point they came up with the, with the following study.
I hope nobody's offended by a picture of a relatively attractive woman with
relatively few clothes on, cause here we go.
They would present something like this to the patient very quickly.
present this image but they would present it so that only the right hemisphere
would see the image not the speech not the left hemisphere.
and so what would typically happen is the patient would blush, okay?
It's kind of uncomfortable to see an image like this while you're sitting in
a, in a testing room with a bunch of you know, people in lab coats around you.
and so the person would blush, but here's the interesting thing.
When the, when the doctors said why are you blushing, the person wouldn't just
say I don't know. They would say, and that's, let's be
clear about this, when they're speaking, it's the left hemisphere speaking and the
left hemisphere did not see the picture. But they would say things like the
following, oh, I just thought of a bit of an off-color joke, I just remembered this
off-color joke. And it kind of embarrassed me to remember
it in this situation. And they would say, well, tell us, what
was this joke? And the person would typically say
something like, oh I can't, I can't remember right now and I, I, I don't want
to tell it anyway but that's, but that's why I blushed.
Okay, now why is this interesting? It's interesting because the person
showed like what you'd expect the left hemisphere to say is I did not see
anything. But instead it looked like the left
hemisphere, the one with speech, convinced itself of a new reality that
explained it's behavior. It's like the left hemisphere noticed the
blushing, felt the blushing, could, could from previous associations, could
identify in a vague sense, where that blushing came from.
That blushing came from some sexually inappropriate thought occurring in this
context. So it's like the left hemisphere could
get there and then it built a story around that.
It, it created this story that was consistent with its behavior.
And this started a whole notion that, that's still alive and well in psychology
and debated pretty rigorously about the role of consciousness.
There are some figures in psychology who believe that this is really what
consciousness does. That our behavior in the real world, is
in fact influenced primarily by stimuli around us.
and so the stimuli just invokes certain behaviors in us.
And then we essentially watch ourselves, and tell ourselves stories that explain
why we behave that way. So the consciousness is in a sense
interpreting our behavior, coming up with a theory and then we own it.
Once we come up with a theory we believe that theory to be true.
And this kind of notion of consciousness coming after the fact you know really
flies in the face of the notion of us consciously deciding to do things.
So it's really fascinating and these split brain studies really fueled that
whole notion. I mean it's really, to really get a sense
of the split brain phenomenon, you really need to see somebody.
So I've got a video here of Joe the Split Brain Patient where you can actually see
a, a split brain patient behaving in some of the ways I've told you about.
So really check that out because that, that will make it I think it will make
the magic? Is it magic?
I don't know if magic is the right word. But the, but the oddness of it really
stand out. This is a video of Michael Gazzaniga
himself, so you can get a sense of the personality and he will talk about the
split brain studies a little bit. So, hear a little bit from somebody who
was right there. and now we have a couple of readings.
So one is a nature article all about Split Brain Study, A Tale of Two Halves
and another one is an article on Psychology today.
so written in different levels, but again, all about the same phenomenon and
the impact it has had on our understanding of the brain.
The connections between the hemispheres and how this all relates to human
consciousness. Very cool stuff, and I think it'd really
make you have a, have a deep and intense appreciation of those three pounds of
tissue in our, in our skull. All right, cool.
So that wraps up week two. we're going to have a, a little bit of a
activity after this week, so, so check out for that for the announcements.
and then we're going to continue on our way through a bunch of fascinating
psychology experiments, and I, I look forward to doing that with you.
Have a great time. I'll see you next week.
Bye bye. [BLANK_AUDIO]
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