PROFESSOR: OK what I want to do for the first couple of
minutes of today's lecture, well, I guess looking at the
hand-out what I want to do is play fill- in- the- blank with
this great picture of a neuron.
I got to talk about the gross structure of the brain last
time, but I didn't get to say anything about a neuron.
Neurons are the, are brain cells.
Not all are brain cells, right?
This is going to be a neuron.
At least half the cells in the brain would be in the category
of glia, that's a word that comes from the word for glue.
And all the years I was learning about this stuff,
glia kind of got shoved into the category of like support
staff, right?
These were the guys who cleaned up after the neurons
who were doing all the cool stuff.
But it's becoming increasingly clear that glia have many
functions to play in brain function beyond the merely
vegetative, and if you go into neuro-science, odds are that
you'll end up learning a lot more about glia than I did
when I was taking the equivalent of course.
But the main units, if you like computational units for
the brain are neurons and so here's a quick tour of a sort
of a canonical typical neuron.
A typical neuron would collect information either from other
neurons on from sense organs through its dendrites, the
word comes from tree-like, because
its branching structure.
So all these little branches making connections with lots
of other neurons or with sense organs in say the skin or
something like that, and the information that the dendrites
collect you can think of as being in the form of little
pulses of excitation or inhibition.
They can be either positive or negative in nature.
They flow down towards the cell body here.
The neuron is a cell like other cells.
It does all those good cellular sorts of things, but
for the purposes, for our purposes, its big job is to
act as a sort of a summator and to ask, how excited am I?
Am I, you know, if I sum up all these pluses and minuses,
am I excited enough to want to tell other neurons about my
level of excitement here?
If the excitement passes a threshold, the neuron sends an
action potential, a signal, an action potential --
no, that doesn't look right, does it?
Well, potential, there we go.
This is why there's a handout, right, because I can't spell
under good circumstances, and I can't spell online at all.
Anyway, that should say potential.
It sends a signal down the axon, the long wire of the
neuron is the axon.
That action potential has a couple of important
properties.
Property one is that it's of a single polarity.
There aren't pluses and minuses, there's
just a single polarity.
And it's a fixed size.
A more excited neuron does not produce bigger action
potential, so how's a neuron going to tell another neuron
that it's more excited?
Would you guess?
It's going to say make more action potential.
So its frequency coating it's level of excitement.
But action potentials are fixed size, and fixed sign
electro chemical signals powering their
way down this axon.
These bumps wrapping around the axon are actually
another cell type.
They're a form of glia known as myelin.
They act as, it acts as insulation, keeping the signal
in one neuron separate from the signal in others, and it
also acts to speed transmission.
There are a number of neurological diseases whose
cause is not a problem with the neuron, but a problem with
the myelin.
De-myelinating diseases, like multiple sclerosis, for
example, have their affect because the insulation is
breaking down, not because the nerve cells themselves are
breaking down.
That signal reaches the arborization of the axon.
It then goes off and talks to a bunch of other neurons.
Or if this was a motor neuron, it would be talking to muscle.
Typically it does not make a direct electrical contact.
If you look at connections between stuff in your
computer, those are direct electrical contacts.
Not the way things work in the nervous system.
In the nervous system, there's a small gap, called a synapse,
and to signal from one neuron to another, an electrical
signal coming down the axon causes chemicals to be
released into the gap.
They diffuse across the gap and bind to receptors on the
other side, and that binding either produces a little plus
or a little minus, depending on the nature of the chemical,
the nature of the receptor, and then the whole process
starts again.
So you go from an essentially electrical signal to a
chemical signal then back to an
essentially electrical signal.
These neuro trans, so called neurotransmitter chemicals are
the targets of lots of the drugs that are used to
modulate mental states, like
antidepressant drugs, for example.
And not just drugs over- the- counter, or not just
prescription drugs.
Let's see, what are you drinking there?
Oh that's just tea, how boring.
Well, I wasn't actually thinking she was probably
putting away a margarita, but that drug would be
working on a synapse.
The caffeine that you are pouring into your brain is
working on neurotransmitter and synaptic properties.
That where you get your chance to affect large numbers of
neurons at one time.
We'll talk more about that later.
Now if I look at my cute little diagram, yes you should
have been able by now to fill in all the --
I wonder what that interesting thing is at the top, actually,
the middle one at the top.
What do you figure?
Cell?
It's not axon.
It's not myelin.
Those are the two at the bottom right and center.
The one on the top right is pointing to synapse.
The one at the top left is pointing to dendrites, and the
one at the bottom left is pointing to the cell body.
So --
AUDIENCE: [UNINTELLIGIBLE]
PROFESSOR: Well, the one on the bottom left, I figure, is
pointing to the soma, or cell body.
I think the one at the top middle is pointing to the
whole thing.
AUDIENCE: Neuron.
PROFESSOR: Neuron, yeah.
AUDIENCE: [UNINTELLIGIBLE]
PROFESSOR: Oh maybe, ah, yes, thank you.
Oh, somebody's been doing their reading.
Yes, OK, she, you are correct.
So the top middle is almost undoubtedly pointing to the
axon, that whole long thing.
And the bottom, what she's pointing out is that the
bottom middle one is pointing to the valleys amongst the
bumps, and those are called the Nodes of Ranvier.
Undoubtedly named after, you know, Joe Ranvier, who I don't
know anything about.
But the way that myelin speeds up transmission is it makes it
possible for the action potential, rather than just
going down the axon in a nice smooth fashion, it jumps from
node to node.
And so that's why the nodes are interesting.
OK, I'm glad we've solved that.
You would have thought I would have thought about that before
putting the thing on the handout.
OK, any other questions about neurons or things, yes --
AUDIENCE: So, soma, is that boring cell stuff happening
all over the place?
PROFESSOR: I mean, well, there's boring cell stuff
happening all over the place.
We shouldn't, of course call it boring cell stuff, because
then guys in like, course seven come in and, well, you
know, put a hit on us and things.
But yeah, neurons are cells like other cells and they have
to do all the, you know, respiratory things that other
cells have to do.
But, you know, our interest in them, of course, is as little
communication and computational units.
Yes?
AUDIENCE: What is the myelin, exactly?
PROFESSOR: It's another cell type that wraps around the
axon and acts as insulation and speed bumps, I guess.
You think of is these as the speed bumps, except they speed
things up rather than slowing things down.
Boy I bet that just confused matters.
OK that said, what I want to today is to talk about why we
do anything.
It's the general topic of motivation.
But, you might, well, you might ask a question like, why
do you eat?
And you say, well, you got to eat because you need -- if you
don't eat, you die.
AUDIENCE: Prove it.
PROFESSOR: Prove it, right.
That's not a stupid point.
He meant it as a stupid point, but it's not a stupid point.
Does a rat -- why does a rat eat?
Does it know it's going to die?
Is a rat sort of sitting there, you know, with
existential concerns about it's --
I don't think so, particularly.
And even if it were the case, now, if you don't you you're
going to die.
Well, so what?
YOu've got to answer --
I mean is it why you do anything is a question that
requires some sort of an answer.
And I will give a three- part answer.
Part one of the answer will be that you are a slave to, you
do things as a slave to the environment.
Part two will be that you do things, as a slave, in fact,
to your own brain, and part three will be to say well,
parts one and two seemed a little simple- minded, we'd
better try and get to a somewhat richer explanation
that might explain why you're sitting here in a classroom
doing this rather complicated activity, since what we'll be
talking about is -- oh, one of the things will be talking
about is the reason that -- is the obvious fact that I'm a
psych professor and not an artist.
So you will have to bear with the fact that, for present
purposes, that is a cat, and that is a rat.
You are neither, are the third part of the lecture will be
devoted to trying to talk up about the richer set of
motivations that you might have, and that even animals
might have.
Well, a good starting place, even if it's a bad bit of art,
would be --
this is an unusually pathetic cat, even for me.
Back in the --
shortly before the turn of the last century, Thorndike,
Edward Thorndike up at Harvard was doing experiments of the
following form: he would take cats, who were hungry cats,
and he would throw them in a box that looked sort of like a
packing crate kind of thing, you know, slats all the place,
and outside of the box is fish, well, bit of fish, but
if I drew a bit of fish, you'd never know what it was.
This at least looks sort of like a fish.
So there's a bit of fish.
You got a hungry cat.
You got the fish.
Cat wants fish.
What's the cat going to do?
Well, the cat is of bouncing off the walls being annoyed
and agitated and the way this box is set up is, well,
they're called puzzle boxes, because in effect, er there's
a trick to getting out.
It might be that there's a lever back here that's
attached to some string and pulley arrangement that lifts
a gate over here, and if the cat happens to bounce into
this lever, the gate goes up, the cat goes
out, gets the fish.
Great, well it's a little piece of fish, and he's a
hungry cat.
And what happens to the cat immediately thereafter, is
Thorndike grabs the cat again, throws him back in the box.
What's the cat do?
Well, whatever the cat is doing, what Thorndike is doing
is measuring the amount of time that it takes for the cat
to get out of the box.
As a function of the number of times that the cat has been
chucked back in the box.
So you've got time as a function of -- we can call
them trials, the number of times the cat
has been in the box.
It initially takes the cat some amount of time.
The next time maybe it's a little quicker, and you got
some sort of a function that eventually gets to some sort
of asymptote where you chuck the cat in the box.
The cat looks at you in a disgusted kind of way.
Goes over to level, says "plahtttt", eats the fish,
says, OK, we gotta do this again, fine.
This is a learning curve.
In fact, this is the original use of the term learning
curve, when you talk about going up the learning curve
and stuff like that, you are invoking Thorndike.
What is the cat learning?
In the 19th century, and even today if you go to, you know,
the animal section of Borders or something like that, there
are lots of books that will tell you about the, you know,
the rich mental life of your cat, and so on.
Thorndike wasn't buying it.
What Thorndike said was that there are good
things in the world.
We'll call those reinforcers.
They come in two forms.
There are positive reinforcers.
Well here, as an example, if you tell a joke and people
laugh, that's a positive reinforcer. you did something.
Something good happened.
There are also negative reinforcers.
Those are also good things.
The jargon IS unfortunate, but a negative reinforcer is a
good thing.
Focus on the reinforcement part not the negative part.
A negative reinforcer is the car alarm is going off, right?
You do something that makes that noise stop.
Right, that's a good thing.
The sensation of something unpleasant, like hunger, for
example, is a negative reinforcer.
It's also a good thing.
A bad thing in this jargon is punishment, is called
punishment, right?
You tell a joke.
The person you're telling the joke to take offense and
smacks you.
That's punishment.
What Thorndike said, what Thorndike formulated, which is
undoubtedly on the handout somewhere,
is th law of effect.
Yes, top of the second page.
He proposed what he called the law of effect.
And he said that something that's followed by a
reinforcer, a behavior that's followed by a reinforcer, is
more likely to recur.
Take the job example.
If you tell a joke and somebody, and people laugh,
the next time the opportunity presents itself, you are more
likely to tell that joke.
The negative law of effect is or is not
on the handout somewhere.
Well, yes, there it is, a little further down under
where it says punishment, the negative law of effect says
that you do something, and something bad happens, you're
less likely to do it again.
You tell a joke.
Somebody smacks you, the next time the opportunity presents
itself, unless you're a teenage male, odds are that
you won't tell that joke again.
Well, it is a separate problem.
This is the burping problem, right?
When you were like 12 maybe, you discovered you could burp
the alphabet or something, and your twelve- year- old guy
friends thought it was really great.
So the behavior got reinforced, and unfortunately
it takes a lot of smacks before you unlearn that, but
that's actually the next lecture.
We'll talk about that next week.
I'm looking at the handout and realizing that I failed to
give you the great bunny example.
And you're going to look at your notes later and wonder
what this is.
But I can use that to illustrate this same point.
I have a rabbit.
Anybody want a rabbit?
We have a rabbit.
It's an accident.
You can have him.
But anyway, this rabbit, when I go down into the kitchen in
the morning, goes berserk.
He's thumping up and down in his cage.
Why is he?
Well, what's he doing?
Well basically, he's signaling that it's time for breakfast.
Not just any breakfast.
If you give him rabbit chow, he keeps thumping.
He's addicted to Reese's pieces, not Reese's pieces,
the Reese's cereal.
It's very sad.
He's a sugar cereal junkie.
And in these terms, what's happened, the way, where his
behavior is coming from, what's driving his behavior,
is he was making some sort of arbitrary noise at some point
when we fed him, and perhaps when we fed him Reese's cereal
the first time.
It was really good.
It was a positive reinforcer.
It made more likely the behavior that he
had just been doing.
So the next time the opportunity presented himself
you went thump, thump, thump, being the right time of day
anyway he got more Reese's stuff.
And now, by this law of effect kind of training, he has
learned that if he goes thump, thump, thump, we'll remember
that it's time for the sweet cereal.
And he gets very disappointed when it turns out that, you
know, that the sweet cereal supply has run out and we're
trying to feed him like some health food stuff.
He's not interested.
Carrots are OK, but only barely.
So why is it that animals --
well, how many of you have cats and dogs?
Cats or dogs, one or the other, you don't
have to have both.
Almost all of you can probably tell me something about the
brilliant, intelligent behavior of this dog that
doesn't sound, or cat, that doesn't sound like this sort
of accidental learning of an association between a behavior
and it's consequences.
This sort of association learning, by the way, is what
I'll talk about, the rules of it I'll talk about
extensively next week.
But why is it that we're so convinced that animals have a
much richer intellectual life?
Well, one possibility is that they do have a richer
intellectual life than this.
The other, the one that Thorndike thought he was
seeing, was what really boils down to selective reporting.
Did I put the whole quote on the handout?
No.
What Thorndike said is dogs get lost hundreds of times,
and nobody ever notices it or sends an account to a
scientific magazine, but let one dog find his way from
Brooklyn to Yonkers, and that fact immediately becomes a
circulating anecdote.
Thousands of cats, he says, sit on thousands of occasions
helplessly yowling, and nobody ever writes to his friend, the
professor, about it.
But let one cat claw at the knob, seemingly in, supposedly
as a signal to be let out, and straight away, that cat
becomes the representative of the cat mind.
What Thorndike thought was, that you are, well at least
the cat, and by extension, you are, a slave to your
environment.
The contingencies in your environment shape what you do.
If the environment rewards you for pushing this lever, you'll
push this lever.
And the cleverness, and the content of that, the seeming
content of that, is imposed from the outside.
It's not there.
It's not necessary.
You can explain it all, you can explain why you do things
purely in terms of these, of this law of effect.
Suitably elaborated.
And as I say, the suitable elaboration on that will come,
will come next week.
The elaboration, by the way, is known as behaviorism and
the school of scientific, of psychological thought, that
says that the explanation for your behavior can be found in
the contingencies that relate your actions to their
consequences in the world and that relates, the
relationships between stimulae in the world.
That gets you some distance, but what is it that actually
makes something reinforcing?
Why should something be reinforcing at all?
What is it about say food that, you know, why does the
cat care that he gets out and satisfies his hunger?
For that, you want to switch to the second form of slavery,
which is this notion that you are slave to your
own brain in a sense.
And the emblematic experiment for that is done some 50 years
after Thorndike is working with his puzzle box.
And that comes from an experiment done by [? Olton ?]
[? Milner ?].
It actually started as a mistake done by [? Olton ?]
[? Milner ?].
Here's what they were doing.
They were sticking electrodes it's into the brain of rats,
into the brains of rats, down into the brain stem, because
what they wanted to do was to study arousal.
Centers down in the brain stem, I mentioned last time,
are intimately involved in things like sleep and wake, so
a general level of arousal.
How do you know if a rat is aroused or not?
Well, one of the ways to measure arousal in a rat is
just to look at the amount of activity
that that rat is emitting.
A rat that's just sort of sitting there is not very
aroused, and a rat that's running around
is presumably aroused.
Great, so they're going to stick an electrode into a
rat's brain and look at general levels of activity.
There's a problem that requires a
control experiment first.
What other than sort of generalized arousal might get
a rat to run around, would you think?
AUDIENCE: [UNINTELLIGIBLE]
PROFESSOR: Sticking an electrode into their brain.
Yeah, well, why might sticking an elecrode in their brain
make them run around?
AUDIENCE: Pain.
PROFESSOR: Pain, it might hurt, right?
You know, so suppose all that happens when you turn on the
electricity, you know, to stimulate the brain of the rat
is it hurts.
The rat is going to run around, but you wouldn't want
to argue that this is a center for generalized arousal.
Plus, you might not really want to be, you know, hurting
your poor rat.
So anyway, here's the experiment that they did.
What they did was they watched the electrodes in the rat, and
they're looking at the rat, and they only turn the
electricity on when the rat is over in this part of the cage.
So, turn on the electricity.
If it hurts, what does the rat do?
AUDIENCE: Runs around.
PROFESSOR: Runs around, but...
AUDIENCE: [UNINTELLIGIBLE].
PROFESSOR: To the other, but hey, ooh, it stopped.
Now wander back over here, oh, no, OK, right?
Everybody knows rats learn this.
They knew that nobody had done this with
stimulation of the brain.
This is so-called aversive learning.
One of the typical ways of doing it is you electrify the
floor of the cage, right?
So, the rat goes over here, discovers that when he puts
his little rat toes on the cage floor over here, there's
electric current running through it and
phew, he's over here.
OK, so that's what they did, and so the rat goes over here,
and on comes the juice for a little bit, and the rat
doesn't go anywhere, and then the juice goes off, and the
rat is wandering around and then the rat comes back over
here, juice comes on for a little bit.
Rat doesn't go anywhere.
In fact, the rat comes back over here.
The rat is sort of hanging around over here, yeah, let's
do that again.
Turns out that the rat was behaving as though the
stimulation was reinforcing.
We could say as though he wanted to be stimulated, but
it's a little dicey to talk about what a rat wants or
doesn't want.
So you can use this more neutral language of
reinforcement.
The rat was behaving as though stimulation of the brain was
reinforcing.
This was a surprise to [? Olton ?]
[? Milner. ?]
The next surprise came when they actually looked at where
the electrode had gone in this particular rat's brain.
That's the mistake part.
It turns out the electrode had bent, and instead of being
where they wanted it in the brain stem, it was in the
chunk of brain known as the lateral hypothalamus.
At least we think it was in the lateral hypothalamus.
Don't actually know, because not only did the electrode
bend, but then they lost the brain.
Subsequently, they did very well for all the
mistakes they made here.
Hypothalamus.
So, what they did that was to deliberately stick electrodes
into the hypothalamus and to set the experiment up in a
more formal fashion, beautifully illustrated here
by my rat, who's got an electrode in his brain, and
that's a battery up there.
And that's a lever.
Now the rat can go off and self- stimulate.
He can go and choose, if he pushes on this lever, he gets
a little pulse of electricity to his brain.
And what does he do?
Indeed, rats with electrodes implanted in the right bits of
the lateral hypothalamus will sit there and work for brain
stimulation, the way another rat might work for rat pellets
water if it's thirsty or something like that.
And they'll work hard.
The most dramatic version I can recall reading is a rat
that will work bar pressing 7,000 times an hour, I think,
for to keep the brain stimulated there.
So this is apparently good stuff.
Not everything there is good stuff.
There are chunks of brain where the rat will work
actively to turn off the stimulation.
So again, so turning on the stimulation would be a
positive reinforcer.
Turning off an aversive stimulation, whether it's
electricity to your feet or electricity to the wrong part
of your brain, that's a negative reinforcer.
So you know, there's current.
If you push the button the current stops.
That's good from the rat's point of view.
In various surveys of rat brain, it turns out there are
more positive locations than negative locations.
I don't know.
You know, we don't know if that's true of humans, and we
don't know if that means anything -- actually the
study, the study that I noticed this morning that I
was thinking of here says that they're 60 percent, in this
one study, 60 percent neutral locations, 30 percent
rewarding locations, and 5 percent aversive locations.
Now the mathematically sophisticated among you will
notice that adds up to 95 percent.
And neutral rewarding and aversive would kind of seem to
cover all the possibilities here, so I have no idea what
the other 5 percent of neurons we're doing.
That seems a lot for rounding error or something.
Anyway more pleasant locations then unpleasant locations.
Now, around this time, somebody who is a science
fiction buff should say, I've heard this before, it shows up
in one of several classic science fiction stories.
The world is full of science fiction stories written by
people just like you, which is to say people who heard an
introductory psych lecture and thought I can make a
story out of this.
Memento, is perhaps the most recent movie example of that.
We'll get to that lecture later on in the term.
Anybody familiar with the sci fi story that's
related to the rats here?
Any of the various sci fi stories?
AUDIENCE: Mrs. Frisbee?
Is
PROFESSOR: Oh, no.
Mrs. Frisbee and the rats of NIMH.
What's -- no, apart from the fact that NIMH is short for
the National Institute of Mental Health and they don't
much care for that.
But what are the rats of NIMH doing?
Oh no, they're busy taking drugs and
getting smart, right?
Na, Na. they're not sitting there stimulating their little
selves, yeah.
AUDIENCE: Terminal Man?
PROFESSOR: Yeah, Terminal Man, that sounds right.
What's Terminal Man's issue?
AUDIENCE: He has epileptic fits, [UNINTELLIGIBLE].
PROFESSOR: And it does give him pleasure, yes.
OK that's -- yeah.
AUDIENCE: Flowers for Algernon?
PROFESSOR: Flowers for Algernon?
No, what's he doing?
Is he being stimulated?
AUDIENCE: [UNINTELLIGIBLE]
PROFESSOR: Oh yeah, but he just becomes a super smart rat
like the rats of NIMH one.
He's got a different --
we don't know how to make super smart rats, we just know
how to make rats who will work hard on pushing levers.
The Terminal Man one is one of the sci fi examples that I
know about.
Anyway, look, the critical issue that gets people writing
science fiction stories is, suppose we did this to a
human, would that human, could you killed somebody by hooking
them up to self- stimulate their pleasure center, and
they would kill themselves.
How would they kill themselves?
By, you know, sitting there, oh, oh, oh, and forgetting to
eat, right?
Well nobody's ever done this in humans of course.
It's been done in rats.
And if you put a lever a lever that gives food next to a
lever the gives stimulation in a good spot in the rat's
brain, the rat will sit there and work away on the self-
stimulation lever.
And at least in some of these studies, well, every now and
then, sort of, say oh, get a little food, OK, back over
here to the video game stuff.
This is really good.
This is what your parents thought you were doing, right?
Yeah, come on down and eat dinner.
Oh, Mom, I can't put it on pause, yeah.
Anyway, the --
would an animal actually kill itself?
Gleitman says that hungry rats will opt for self- stimulation
even though it literally brings starvation.
And then he sites an article that I went back and read, and
the rats in that study didn't starve themselves to death,
because the researchers wouldn't do it, presumably
because it seemed unethical to actually let a rat starve
itself to death.
But they will certainly reduce, you know, they'll
certainly get themselves pretty hungry while amusing
themselves with the, by stimulating their brain.
There was a hand up, oh there still is a hand up
there, look at that.
AUDIENCE: [UNINTELLIGIBLE].
PROFESSOR: I don't know that the truth or falsity -- so the
story is a guy played video games for, what was it, 74
straight hours, 74 straight hours in
Korea, and then he died.
Actually the Korea part is good here, because I have no
idea whether this is true one way or the other.
It has all the Hallmarks of a so- called urban legend.
It has a grain of plausability, and is just sort
of one step removed from checkability.
It's like the Kentucky Fried breaded rat, right?
Everybody knows somebody else who knows that their cousin
got a breaded rat once.
There are whole books of these things, they're great.
I don't know, maybe somebody managed to play video games
until they died.
People do all sorts of stupid things.
I don't recommend trying this yourself.
In any case, rats will work very hard in order to
stimulate different parts of their brain.
What is it that they're working for?
The evidence suggests that they're not just working for
some sort of disembodied pleasure, but that they're
working for the reward associated with one or the
other of sort of basic hard- wired, innate reward systems,
that you come with, but that the rat comes with too.
The reason that in this aspect of the slavery story, that
you'll work to get the fish if you're the cat is that you
came predisposed to think that hunger is
bad and food is good.
This, yeah, look, it doesn't take very sophisticated
evolutionary psychological theory to think this might be
a good idea.
Organisms that went into the world thinking that hunger is
good and food is bad had many fewer progeny than the ones
who thought that hunger was bad and food was good.
So it's not that surprising that you've got circuitry that
says if you're hungry you want to go and eat something.
And the centers that are being stimulated are in chunks of
brain that if you mess with them, mess with the rat's
ability to regulate its eating.
So there's a wonderful picture in Gleitman of a rat with a
hypothalamic lesion, a lesions in this
sort of chunk of brain.
The specific lesion in this particular rat is in a chunk
of brains that seems to be important in telling you when
you're full.
So this rat never knows that he's full.
With the result, he just keeps eating.
And so there's this picture in chapter three of a rat on a --
some of you may already have seen it, of a rat on one of
those diets scales.
You know, and he looks like a fury football.
He's just sort of overflowing.
that's And that's because he's got a specific lesion in this
little specific chunk of brain.
How do we know that's what's going on here?
Well, you got a rat who's working a way to be stimulated
in this little particular chunk of brain.
And if he, so let's take this little chunk of brain, if he's
a full rat, if you feed him up, he doesn't work as hard.
It's just not as interesting.
You know this, in your own --
so, you like M&Ms let's say.
You're willing to put, you know, you're willing to push
the lever to get the M&Ms, right?
You're willing to put the quarters in the machine.
Would you do that forever?
No, because eventually you get full and the M&Ms kind of look
disgusting.
So the same thing happens here.
So the pleasure that the rat is getting is modulated by
satisfying, you know, the thing about direct electrical
stimulation is it gives the sensation of the satisfaction
without actually satisfying anything.
So, if you're getting the oh, the M&M is good thing without
getting the M&M, you can sit there, oh the M&M is good
forever and ever, and keep working on it.
Okay, so that's this little chunk of brain.
You go over to this other chunk of brain where the rat
will also work hard, and that rat doesn't care if he's full,
that rat cares whether he's mated recently.
So you know, this one is part, you know, this little chunk of
brain is presumably related to the reward systems having to
do with sex and mating.
Again, it doesn't take an evolutionary psych genius to
figure out that this would be sensible stuff for a
brain to come with.
Organisms that didn't find mating rewarding didn't leave
many offspring.
Yeah, just didn't work out that well for them.
And so, you know, there's another reward system.
Similarly, for thirst there are separate reward systems.
OK, so, in some sense you end up doing stuff in order to
light up little pieces of brain or to turn off little
pieces of brain.
That's the sense in which you are a slave to your brain.
Now, you, know that only gets you so far, because that's
fairly simple.
You know, eat food, little hunk of
brain says you're happy.
Your behavior is somewhat more complicated than that.
How do we get to that more complicated behavior?
Well, let's stick with the M&M example.
How did you get to the M&Ms?
Well, you got to go down to the vending machine and put
the money in.
And how do you learn to do that?
Well, maybe you learn to do that by a chain of
associations back to the M&Ms. M&Ms, oh, they're good.
Getting M&Ms becomes good in its own right.
Somebody gives me M&Ms, that becomes rewarding by
association, with the fact that I will now get to eat the
M&Ms. This machine will give me M&Ms, but only
if I give it quarters.
So, I learn to give it quarters.
That's an interesting ring.
It sounded like a regular old phone.
Put them on vibrate.
That's what I do, because let's see, well, yeah, it's
just about the right time.
I should be vibrating any time, woops, not that one.
My tenth grader tends to phone in after school which is
great, the only thing is that after school two days a week
turns out to be here, and it's not a good
time to take a call.
Anyway so ah well, so the tenth grader, he likes M&Ms.
He needs quarters.
So, he's got to emit behavior that I like so I'll give him
quarters right?
And so you can see how you could build back from a
primary sort of reinforcer, like food is good to something
much more remote like cleaning my room is good.
Why is cleaning my room -- if I clean my room, daddy gives
me quarters.
If daddy give me quarters, me I take quarters.
I put them in machine.
Machine gives me M&Ms and all is good.
That's OK, but it probably doesn't do quite well.
The brain suggests to us that that isn't quite enough, for
organizing even the feeding behavior of a complex
organism like us.
Suppose that you are doing --
that what gets you to do your complicated sort of behavior
around feeding is the fact that you're hungry -- oh,
chapter three will tell you all about how you know that
you're hungry.
It's lovely sort of engineering work.
You've got little detectors, receptor is in the blood.
They're doing things like keeping track
of blood sugar levels.
When those levels drop, chunks of brain become active.
Activity there is apparently aversive, probably
corresponding to what you and I think is hunger.
When you get sugar in, activity there drops.
Lovely, beautiful sort of control systems.
Stuff worked out in great detail and discussed in
considerabe detail in chapter three, but suppose you're not
living in your food, right?
Suppose you're, well suppose you're like out on the plains
of Africa somewhere, and the M&Ms aren't just sitting over
there in the vending machine.
They're running around, and you're going to have to hunt
them down, right?
If you are sitting around until the blood sugar level
gets low enough for unpleasant things to happen in these
hard-wired chunks of brain, to make you think, OK, all right,
I'll remember this, M&Ms or wildebeest s, whichever it
was, they're good.
I can eat them.
To get to wildebeest , I got to go clean my room -- anyway,
there's some complicated thing that you gotta do.
But if you wait long enough before starting, you may not
get it, the job done in time, right?
It's going to take you a while to hunt down the wildebeest .
If you wait till the gas tank is almost empty, yeah you may
find yourself flat out on the plains with,
you know, no food.
So it would be useful if something got you up and
mobilized for activity before you were actually hungry,
before you actually were in some sort of desperate need.
And the distinction that gets made, and I trust is bolded at
the, yes, it's down there at the bottom of page 2, is the
distinction between consummatory and appetitive
behaviors, or consummatory and appetitive pet motivations.
consummatory ones, are the ones we've been talking about
so far, eating M&Ms, that's good.
Appetitive ones are ones where the act of looking, if you'd
like, or getting yourself in a position to
consume is itself rewarding.
In that case of food, that might be sort of the thrill of
the hunt kind of thing.
Think about cat, right, your cat that likes to jump on
anything that moves.
Why is that?
It's because the cat is hard wired to like hunting stuff.
It's just fun to grab stuff and kill it.
Now that's a useful thing to do if you are a cat-like
animal because then there's going to be something around
to eat when those blood sugar levels drop and you need to,
you know, chew on a wildebeest for a while.
And it's pretty clear that we have similar, actually, it's
pretty clear that in yesterday's political news
that we have similar sorts of circuitry in ourselves.
Yesterday the assault rifle, the
assault weapon ban expired.
Bush spent a lot of time not talking about it.
Kerry spent a lot of times saying I'm a hunter.
I love to hunt.
I love to jump on moving things and stuff like that,
but I've never done it with an assault weapon.
You don't need to use an --
he was on the --
but he was very big on pointing out that he loves to
hunt, because apparently there's lots of people who
love to hunt and go out and you know, shoot things and
sometimes eat things.
This is presumably related to, this is presumably a form of
appetitive behavior in humans.
If you don't happen to love to hunt it doesn't mean that
you're missing a piece of your brain.
Another realm where appetitive behavior is important is in
the sex and romance department, right?
If it were not the case that the act of looking up for a
mate is motivating in its own right, well, what are you
going to do, you know, wait around until all of a sudden,
I don't know, whatever levels it is drops low enough, ugh,
it's time to mate?
It's just not the way we organize our, it's not the way
we organize our behavior.
Our social lives suggest that we find a degree of pleasure
in the appetitive aspects of seeking a mate, not merely in
the consummatory parts of it.
So you come with a set of motivations that get you
motivation, in the sense of getting you to move, that seem
to come with the systems.
These can be quite specific -- by the way, that's the notion
of preparedness that I see, what is related to this notion
of preparedness that I see is actually above where it says
consummatory and appetitive behaviors on the handout.
you are surprisingly fine tuned by, presumably by the
history of the species.
So for instance, you are built to get away from scary things
that are going to hurt you and that seems reasonable enough.
And that can be specific enough to the point that it's
easier to get you to be scared of spiders and snakes than it
is to get you to be scared of bunnies and chickens.
That sounds kind of obvious, but there's no obvious reason
why, in fact, one of the famous experiments in the sort
of behaviorists tradition has a little baby known to history
as Little Albert -- there's a great film from the 20's of
this Little Albert is sitting there, he's playing with a
little white bunny.
John Watson, founder of American behaviors, then
sneaks up behind Little Albert with a gong and
pow, rings the gong.
Little Albert goes, if it was a cartoon, would go straight
up in the air, and is you know, scared out of his Little
Albert gourd and is screaming and crying and stuff like
that, and you know, it's kind of harsh for Little Albert,
but then you bring Albert back and show him the bunny again.
Does he want to play with the bunny?
No.
Does he want to play with anything that's white and
furry, including Santa Claus, apparently, I seem to recall.
Guys with bushy white beards --
he recovered by the way.
He didn't grow up to be a psycho or anything, but you
can train, so you can you can train somebody to be scared of
rabbits, but it's easier to train them to be scared of
snakes, at if they were prepared by the history of the
species to be scared of things like snakes and spiders.
OK, so you're a slave to the environment because your brain
responds in rather specific ways to the environment but
you are a lot more complicated than that, or at least you
feel like you're a lot more complicated than something
that's just a bundle of sort of engineering responses to
glucose level low, must go find wildebeest.
And I want to spend the remainder of the lecture
talking about some of those complexities, but first I want
to give everybody a chance at least to stand up and stretch
a little bit and fan themselves because
it's warm in here.
I Oh, yes, yes you want your little form right now?
AUDIENCE: Sure.
PROFESSOR: Ok send this form back, and I trust that means
that you can be here at like five of two --
AUDIENCE: [UNINTELLIGIBLE]
PROFESSOR: Yes, well, it's not useful after class.
OK this is all the information I have.
If there's a problem let me know.
And your name is?
AUDIENCE: Jean.
PROFESSOR: Jean, nice to meet you, and I trust that you'll
see happily erasing my boards.
OK, let us reconvene here.
Here's the deal.
I will typically try to be good and remember to give you
a chance to sort of stretch your limbs a little bit, and,
but it'll be a short stretch.
So, you know, but why am I telling you this?
It's the guys who thought they were off for ten minutes who
are now halfway down the hall to get the M&Ms who had the
problem, but anyway.
Or the ones who are out looking for wildebeest are
really in trouble.
You might wonder what the role of the emotion
is in all of this.
Clearly, motivation and emotion are closely related.
They both talk about feeling a lot, you know, that there's
this feeling of hunger, but the emotion part is well, one
way to think of it would be as a sort of a language, a symbol
system, that's a short hand that helps you mobilize you, a
way of talking to yourself about what resources you might
want to mobilize.
Oh, I feel fear.
That means I should do the following sorts of things.
And it helps you generalize from event to event.
I feel fear now.
I felt fear before.
You know, maybe there's some sort of relationship that I
ought to be noticing.
And perhaps, one of its most important uses is as a form of
communication between people or between
animals more generally.
If I am afraid, let's go let's go back to the plains of
Africa and switch sides.
If I'm a wildebeest, and I see the leopard over there,
stalking through the under brush, I should be afraid.
If you're not seeing the leopard, but you're seeing me,
I look afraid, and you're the rest of the wildebeests, you
should be afraid too.
It's a good idea if you pick up on the way that I feel.
Now we tend to devalue that a bit because we tend to use
verbal communication a lot to convey information back and
forth, and for some things it's obviously a much more
useful technique.
I mean trying to teach psychology by a set of
emotional expressions would not --
I can't even conceive of how I would go about doing that.
However, we probably over value the straight, this sort
of straight verbal nature of communications,
even between humans.
Obviously, non-verbal animals are going to have to use some
other form of communication, but even among humans, we
underrate the value of this current of emotion information
transmission.
Perhaps the clearest example of this is email, where, how
many of you at some point have gotten into trouble on email,
because email has the characteristics of
conversation without the tone of voice.
You said something that you thought, that you meant
sarcastically, or you thought was funny, and somebody else
read it as flat prose, and they were not amused at all.
And then you got -- actually that's the root of all these
little smiley faces and all these symbols that I don't
know from nothing.
You all know this.
There's some very elaborate vocabulary of basically
emotional tokens for instant messaging or for email because
it lacks that emotional tone of voice, and without that,
the quality of the communication goes down.
So you've got emotions at sort of a super ordinate language
that allows you to talk about motivational states, even in
the absence of any sort of verbal language.
I think you could probably make a convincing argument
that basic motivational states exist in
very, very simple organisms.
I mean any organism has to figure out, has to have in
some sense the motivation to feed itself and to reproduce.
It's only when you get to more elaborate organisms do you get
something that looks like the sort of emotional life that
you and I might have, where it's being used, as a sense, a
form of communication.
But look, so far, we're still in pretty simple terms here.
You know, we've got, sex and reproduction is good.
Getting eaten by the leopard, that's bad, and so on.
Where we want to get, and where the chapter on
motivation, for instance, never gets, is you know, sex
and reproduction, good, eternal damnation, bad.
Or something like that.
Or how do you get from, you know, hunger drives and sex
drives to thou shall not murder and you know, I want to
grow up to be a chemical engineer, or
something like that.
It's those rather more complicated motivations that
require more than just feedback loops and the lateral
hypothalamus to make a good story.
Now, one step to a richer account of why we do anything
is to broaden the set of motivations.
I have pointed already in the direction of one act of
broadening that set, and that is this notion that if I'm a
frightened wildebeest, you should be a frightened
wildebeest.
This is the notion that emotions are catching across
individuals.
We talk about, on the handout I put it as empathy and
described it as a social emotion, and it's a social
emotion in the sense that it helps to organize social
behavior, interactions between people.
So, for example, well let's start with a bit of evidence
that this comes with the system, that it's not
something, I mean you spend a fair amount of time trying to
teach people to be more empathic, but the core of it
is there from the start.
So, how do you know it's there from the start?
You take a baby, here's a baby, here's a
bunch of other babies.
Poke this baby.
What's this baby do?
AUDIENCE: Cry.
PROFESSOR: Cry.
What do these babies do?
They also cry.
Why?
You haven't hurt those babies, but those babies have, in a
sense, caught the emotional state of the other baby.
Not only do babies catch their emotional, each other's
emotional states, but you are all here today because of the
same sort of empathic reaction.
When you were a little pre-verbal slug, and you were
hungry, what did you do?
AUDIENCE: Cried.
PROFESSOR: Yeah, right, you cried, right, is
all you could do.
And how did that make your parents feel?
Well, some of you are here today because you were lucky
because apparently it made your parents feel angry, and
then -- which it probably did, particularly at weird hours --
Mara is looking at me.
How old is the kid?
AUDIENCE: Four-and-a-half months.
PROFESSOR: Four-and-a-half months.
We can check out -- if you haven't met Mara, she's the
head TA, so she knows everything about the course
and what recitation you're in, and we can also use her
all-term as the official parent person, or at least
parent of young child type person.
She will confirm that when you're baby cries, you want to
make that baby stop crying.
Fortunately, most parents, the ones who want their genes to
make it into the next m make the baby stop crying by doing
things like feeding it and changing it
and stuff like that.
If it didn't make you feel bad, if the crying baby wasn't
the car alarm of the developmental world.
Hey, the baby is crying.
Oh, that's cool, you know?
Didn't know the baby could make that noise.
Wonder what happens in a little -- the baby cries, you
feel bad, and you doing something about it.
And, you know, that's how you end up getting there, getting
to the point where you can take care of yourself, because
somebody else was willing to take care
of you at that point.
And obviously, again, in non-verbal animals, like the
rest of them, it's really useful if, when your infant
animal is feeling uncomfortable, you recognize
the need in some fashion and you and you do
something about it.
So in a sense, emphathy is sort of a prerequisite for
successful parenting.
And this empathic catching of fear is a useful way to keep
yourself alive.
If you don't see the danger, but somebody else does, that's
-- oh, and it's a good, it's good for keeping you alive in
other ways too.
I won't do it, but if I were to suddenly decide to make
myself throw-up, a bunch of you would feel
really lousy, right?
You know this.
By the way, this is one that goes away when
you become a parent.
You can modulate these things over --
if you felt incapacitatedly nauseous every time your child
threw-up, your child would never make it, because -- you
just got to deal and clean up.
But at this point, if I throw up, you're going to feel sick.
Some of you will throw up.
I shouldn't keep talking about it because some of you will
start feeling gross just thinking about it.
That's also useful.
Why?
Because if I ate the wildebeest, and it was a bad
wildebeest, you know, and we're all vultures on the same
wildebeest here, if I'm looking kind of sick, you
might as well get rid of wildebeest now, because it's
just not going to be doing you any good.
So this catching businesses has its utility.
Now it's not uniformly a good thing, because you can catch
anti- social emotions just the way you can
catch pro- social emotions.
So when you see seemingly incomprehensible events, like
how in the world can you explain something like gang
rape or a massacre in a war zone?
Part of what's going on there is the same sort
of emotional contagion.
If one person is in a murderous rage, people around
them, around that person, can catch the murderous rage, just
the way they can catch the fear or catch the nausea.
It's not just sort of a pro social motivation, but empathy
does serve the function of organizing larger scale sorts
of behavior.
Oh, now, how does this contagion actually work?
How does emotional contagion actually work?
Interestingly, part of, the sort of reflexive mechanism of
it seems to be that when you read my emotion, you also
mimic my emotion.
It is most clearly seen with facial expression.
If I smile at you, you will smile.
You may not smile much, but I'd be able to pick up, if I
was recording from your facial muscles, I would be able to
pick up a transient smile flitting across your face.
Why is that important?
Well how do you know if you are happy?
Well, it turns out -- and this is, one of the senses in which
feelings, emotions our feelings is that you go out
and you feel yourself and ask yourself, how do I feel?
Part of that is to feel your face, in effect.
You know, how does my face feel?
Well, I seem to be smiling.
Why would I be smiling?
I must be smiling because I feel good because only dumb
people smile when they're miserable, right.
You know, well, there are various social circumstances
when you might do that, but anyway, it's useful
information.
You can actually try to demonstrate this --
here's an exercise for the reader if you like, I've done
it as one of the writing assignments for the course in
various years.
It's sort of fun.
Take say ten events of about the same duration, say an
hour, because that works for a lecture, for example, now a
lecture, recitation, dinner, a few events, study break,
events that are going to take about an hour.
Take ten of them.
Shuffle them around.
Put five of them in one pile randomly, put five in the
other pile.
Then deliberately either try to smile or frown through, you
know, smile through pile A and frown through pile B. And ask
yourself, you can ask yourself a variety of questions, the
most obvious being, how do I feel, and what's the effect on
people around me?
If you frown like an idiot, the effect may be to make
people smile, but if you, but you know what you, you've done
the experiment.
You were doing it like when you were early adolescences is
one of the best times to do this particular experiment.
You show up at the dinner table.
Everybody's in a pretty good mood, but you're not.
By the end of the meal, you know that nobody's in a good
mood anymore, right?
Well, you can still do this.
I mean I'm not sure how ethical it is as an experiment
to try out on your friends at dinner tonight, but it you go
to dinner feeling like junk and acting that way, you can
make everybody else miserable too, and isn't that great?
But more to the point, for the present point, you
can make your --
all that's sappy garbage about a smile is your umbrella turn
out to be sort of true.
And it doesn't even have to be a real smile.
If you take, no that's somebody else's pen.
I'm not going to do it with somebody else's pen.
If you take a pen, this is an experiment that was published
a few years ago, take a pen and hold it like this, that
forces your face into sort of an idiot smile, whereas
holding a pen like this does not.
It forces, it actually forces into a bit of a frown.
If you do this, and don't --
I'm already spoiling the control aspect of the
experiment.
You don't tell people why they're doing this.
You just make them do it for awhile.
The people who do this feel better than the people who do
this, because the chunks of your brain that are saying,
how do I feel, are rolled up and encapsulated enough that
they don't know, he's smiling, he must feel good.
The fact that he's smiling because he's got a pen in his
mouth turns out -- not that it matters, but it
doesn't matter that much.
So if you're feeling down, bit on a pen, you'll feel much
better about it.
OK, well look, so you can get a certain amount of work done
by broadening the set of available emotions, available
motivations that you want to talk about.
Why isn't the world a better place?
You've got this empathy thing going on.
You've got this beautifully wired up brain that you're a
slave to that's designed to make you eat and mate and do
all those sort of good things.
Why isn't the world a better place?
Why doesn't it work better?
I point, look, I can't solve that in the remaining 12
minutes or so.
I pointed to part of the answer just because you catch
emotions doesn't necessarily mean you catch good ones.
It is also the case that not all of your motivations may be
entirely benign.
So, for example, what's it got on the handout?
It doesn't have on the handout, but aggression seems
to be, there seems to have deep biological roots to it.
It is a not unreasonable reaction to a
world of limited resources.
It's not necessarily a nice reaction to a world of limited
resources, but, you know, if you are, if there's a limited
number of mates out there, and you can punch out all the
other guys and grab all the women, well, then you get the
have more progney than the guys you punched out.
Fortunately human society is not organized
particularly that way.
But there are plenty of animal societies that seem to be,
elephant seals, you've seen these guys on, you know, your
favorite cable channel, right?
They come up in thousands on the beaches near Antarctica
and stuff, and, you know, these huge male guy elephant
seals have like a thousand women -- what is a woman
elephant seal?
I don't know.
Anyway, a thousand female elephant seals in their harem,
and they have these huge fights over who gets to have a
-- you know, they can't share.
They just never went to preschool and learned how to
share properly.
But part of, there is certainly enough aggression in
human behavior to make it clear that that sort of a
motivational system is going to lead to a certain amount of
conflict in the world, and it's not all going to work out
as sweetness and light.
People like Freud proposed that there was actually a
death wish motivation out there.
Thanatos Freud's term.
I might talk about that more later in the term.
So that's, the possibility that there are motivations
that themselves are not particularly nice, if you
like, is one possible reason that the world is not a
perfect place.
But perhaps the most useful way of understanding why the
world doesn't work out so well, necessarily, given all
this marvelous motivational hardware if you like that
you've got is that, look, most of the time when we study
these things, we study a motivation in isolation.
You want to study this cat's ability to learn about the
puzzle box and the relation to the motivation of hunger, you
take a hungry cat.
You put it in a box.
The only thing of any interest here is how to get out of the
box and get to the fish.
You know, the only thing of interest here is, you know,
there's a rat who is maybe a hungry rat.
In this case, he's got an electrode now in the feeding
centers of his brain.
And all the other things that a rat might do are just not
relevant here.
You don't operate in the world like that.
You operate in a much more complicated space.
I mean we can cartoon that here.
Here's you.
You know, if we got in the lab, maybe we can just do an
experiment on when you do or do not eat, but that's not
what you're dealing with out in -- well, alright, here is a
way to get to this question.
How many of you have ever eaten something when you
weren't hungry.
Well what's the matter with you, right?
You know, I just told you, you've got this elaborate
stuff I've already erased the lateral hypothalamus.
You've got a brain full of circuitry designed to make you
eat when you're hungry, and not to eat
when you're not hungry.
And you don't look like that fury football with a lesion in
your brain.
So what's your problem that you're eating
when you're not hungry?
Well all right, let think about this is sort of
metaphorical terms.
Let's imagine a situation where there are lots of
different possibilities pulling on you.
Suppose you're at some sort of a social gathering of some
sort, there are lots of possible things, lots of
motivational systems at work at any one time.
I mean one of the things you could probably do is eat.
Maybe there's the possibility for fighting,
mating, sleep, study.
You know, you could do all sorts of, you know, run.
You could do all sorts of stuff.
And all of these things, each of which may have it's own
beautiful hard- wired core and it's an elaboration of a
lifetime of learning, all of these things are pulling on
you at once.
And, well, you know, all right, so maybe the sleep
motivation and the study motivation are pretty weak at
any given moment, but you know, let's suppose that
there's pretty strong drives in this direction.
OK, so if you're sitting in this exciting vector field,
where the resultant?
Right?
Right.
AUDIENCE: [Laughter]
PROFESSOR: Now, I'm not proposing this as a serious
model of why you might eat when, well I am
proposing it as --
I'm not proposing it as a serious mathematical model of
why you might eat, but I'm supposing it has a serious
metaphor, that you might engage, and it's going to be
much more complicated than this, right, I mean part of
the reason, it's not just that there's, you
know, want to eat?
Want to fight?
Oh think I'll go eat instead.
But, want to mate, you know, here?
Now?
Can't do that, but they're, you know, there those brain
stem chunks of general arousal, oh yeah, well, I've
sort of got a lot of activity here
that I gotta do something.
So you end up with sort of displacement activity.
The problem is that the world is a complicated place, and if
you were ever going to reduce this to map, it's going to
have a lot of variables.
It's going to end up with a lot of
variables in the equation.
Most of us manage to do OK.
We eat when we don't want, but that's all right.
Later on in the course, you end up talking about, you
know, perhaps the people where you find that they're fighting
too much or something like that.
No lecture Thursday, just to reiterate, I will sign all
those lovely add drop cards.
I'll see you next week.