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JESSICA SOMMERVILLE:
So this morning
we heard Laura give a
really beautiful overview
of her research program,
and my talk today
is going to be a
little bit different.
I'm going to talk
about some things that
are going to be
highly related to what
Laura was talking
about, particularly
at the end of her talk.
But because this is like brand
new hot off the press work,
some of it's actually ongoing as
you'll see as the talk unfolds.
I'm going to be focusing on a
more kind of specific detail
level.
So I may tell you about
four different studies,
three of which are completed,
one of which is ongoing.
And they all have to do
with infants' sensitivity
to costs and benefits.
OK.
So, as we all know,
cost benefit analyses
are really central
to the decisions
we make at both a conscious
and an unconscious level.
And, of course, there's
all kinds of different ways
that we make decisions, right?
But one of the
things that we often
do when we're
making a decision is
we think about what rewards do
we anticipate from following
a particular course
of action, and how
do those compare to
the costs that we'll
incur from performing
that same action.
And we will act
in a sense to try
to maximize the value that we
get out of a particular choice.
That's true of simple
decisions like this, right?
This woman deciding what she's
going to eat for dessert.
And we can also
apply these analyses
to more complex
decisions, like things
like where we're going to go
to college, what kind of career
are we going to pursue,
where are we going to live.
OK.
One of the things that we
heard from Laura this morning
is that cost benefit
analyses don't just
apply to her own behavior
and her own decision making.
She showed some
really neat evidence
that these types
of analyses form
the basis for the inferences
that we make about other people
and that we make
about their behavior.
So that raises the very
interesting question
of the developmental origins
of these types analyses.
And that's what
I'm going to talk
about today,
infants' sensitivity
to costs and benefits.
My talk is going to kind of
have two different parts.
In the first part,
I'm going to be
talking about
cases where infants
are observing other people.
And what the question
that I'm asking there is
do infants-- are they able to
register the costs that are
behind other people's actions?
And then in the second
part of my talk,
I'm actually going
to switch gears,
and I'm going to talk
about infants' registration
and minimization of costs,
the registration of benefits,
to guide their own behavior,
their own decision making.
I'm going to talk about
a particular test case.
And that's the test case of
infants' prosocial behavior.
OK.
And I want to be kind
of specific here.
So across all of
these studies, I'm
talking about cost in
one particular way.
Of course, there's
all kinds of ways
you could operationalize cost.
But what we've been
focusing on so far
is physical effort,
the physical effort
behind an action as a cost.
Why would we start here?
Well, there's several
different reasons, right?
And the basic kind of
evolutionary level, it's
really important
that we can register
and that we can minimize
energetic costs,
effortful costs, right?
Our very survival
depends on that.
We have to metabolically
and energetically budget,
or we won't stick around, right?
So that gives us good
reason that that's
a good starting place in terms
of looking at young infants'
ability to register costs and
minimize cost potentially.
Another reason is that
for decades, scholars
have really given a central role
to effort in decision-making.
And this dates
back to the 1940s,
the whole in Solomon
who postulated
the law of least effort.
So the idea here is that if
there are two lines of actions
that lead to equal
rewards, we're
going to take the path of
least resistance, right?
We're going to seek
to minimize effort.
And then, finally, in
more contemporary work
that's looked at
cost-benefit decision-making,
both in adults and in nonhuman
animals, a lot of this work
comes from the
neuroimaging literature.
Effort has been a fairly
heavily studied cost.
So this is a good
starting place,
because we have a pretty
good understanding of how
effort and various benefits
or reward are integrated
at both the neural and
a behavioral level,
at least for nonhuman
animals and for human adults.
OK.
So the first
question we might ask
is, what is the
existing evidence
in terms of the question
of whether infants
have a basic ability to
register cost behind actions.
And there's really
two different ways
we could pose this question.
We can think about the
question with respect
to infants own behavior,
their own actions.
Is there evidence that infants
will act to recognize costs
and to minimize costs
in their own behavior.
The other way that we
can ask the question
is in terms of infants
observation of other people's
behavior.
Do they recognize the cost
behind other people's actions.
You know, surprisingly
there really
hasn't been a lot of work
that's looked directly
at this when we're
talking about infants
own behavior, their
own decision making.
There is some work from the
weight perception literature
that's looked at
how infants interact
with blocks of different ways.
And so what people will
do in these studies
is they'll present little
babies, nine-month-old infants,
with two blocks that
look virtually identical.
They only differ
from one another
in terms of their
respective weights.
And what these
studies have shown
is if you give infants a choice
between these two objects,
they'll systematically
prefer the light object
over the heavy object.
So one way to think about
these findings is what infants
are doing here is exactly
what we're interested
in, they're minimizing
the physical cost, right?
They're taking the past of--
the path of least effort.
One challenge, though,
for interpreting
these finding is oftentimes
in these studies,
the heavy blocks
that are being used
are beyond infants
lifting capacity.
So what that means is it's hard
to know if these results are
about infants
registering cost per se,
or if what we're
really getting at
is just infants repeating a
sort of successful interaction
with an object that they've
acted on previously.
OK.
So Laura talked a little bit
about this in her talk today.
What about the evidence
of registration of costs
and other people's actions.
And one of the things
that Laura mentioned
that we know from many,
many different studies,
is that infants appear
to expect efficiency
in other people's actions.
Laura showed you
one example of that.
I'll show you a
different example
of that, which comes
from actually a study
that Liz did with one of
her graduate students.
So here we see
someone who's reaching
over a barrier in
order to get an object.
The barrier is then removed.
Infants have the
expectation that that person
is going to reach
directly for the object,
right, rather than performing
that funny arcing motion.
So, again, one way to
think about these findings
is that what
infants are doing is
they're expecting that the
person is going to take
the least costly action, right?
And, in fact, there's
all kinds of costs
to this particular
arcing motion, right?
It's indirect, it
probably takes longer,
it's probably more difficult,
it's more effortful.
And so we wanted to
ask the question, too,
to begin with if infants
were able to register costs.
But unlike in this
situation where
there's multiple
potentially redundant cues
that this arching motion
is a costly behavior,
we wanted to really
kind of focus
in on situations in
which there aren't
a lot of overt observable
cues to the costs underlying
another person's action.
So the way that we did
this is we showed infants
different actions that look
similar on their surface level,
but these actions
differ in terms
of the degree of physical effort
that are required to perform
them, and the way
that we achieve
that is by having infants
watch people lift objects
of different weights, right?
So, obviously, heavy weighted
objects are harder to lift.
They're more effortly costly
than lifting a light object.
And what we wanted to
know is can infants
recognize under conditions
where they have really minimal,
observable cues, no cues
about, for example, straining
or sweating or
things like that that
might be really obvious for
figuring out the effort.
Will they be able to understand
that when someone is lifting
a heavy block, that's a more
effortful action than when
they're lifting a light block.
In addition to that kind
of primary question,
we were also interested in
whether this ability in infants
might be individually variable.
So this might come
as a surprise to you,
but infants, like adults,
are individually variable.
And they're individually
variable, of course,
in many ways.
But one way in which they
vary from one another
is in terms of how
strong they are, right?
Just like human adults, right?
We're variable in terms
of how strong we are.
And we have an
idea, or hypothesis,
that infants individual
differences in strength
might actually be
important for registering
the effort-related costs
behind these different lifting
actions with different
weighted objects.
One of the reasons that
they might be important
is because of core strength
gates the type of experience
that infants are going to have
in their everyday life, right?
If you're a strong baby,
you can lift heavier objects
than a weak baby.
You can also lift a wider
contrast of range of objects,
right?
So we thought maybe
there's something
about individual differences
in strength, particularly,
for babies who are
stronger where they'll
be better at recognizing
the differential effort that
goes along with
lifting actions when
you're talking about
blocks of different weight.
OK.
So let me tell you
about the study
that we conducted to
ask this question.
We tested 12-month-old
infants in this study.
They took part in a
turn taking procedure
where we recorded EEG,
electrical activity
from the brain as it
propagates the scalp.
And in the course of this
task, what they did is
they took part in
different types of trials.
On observation trials, they
would watch an experimenter who
would lift these different
objects or these blocks,
and these blocks looked
perceptually identical
in terms of size and shape.
They were different colors so
infants could individuate them
and keep track of them, but
what varied from trial to trial
was exactly how much
the objects weighed.
So they range from being the
weight of a typical bath toy
to being quite heavy.
So infants can lift
the heaviest blocks,
but they're pretty effortful
in order for infants
to be able to lift them.
In the trials where they watched
an experiment or interact
with these blocks,
the experimenter
would do things like put
the block up on a platform,
drop it into a bucket after full
type of actions where you can
sort of register at
least in principle
the type of effort
behind the action,
and then infants would also
have the opportunity to act.
They could perform the
same actions with objects.
Infants also for
measurement purpose
received baseline
trials where we're just
registering EEG in
response to abstract images
like a checkerboard
pattern, for example.
OK.
So what are we
interested in here?
So, in this particular
study, we were
looking at the suppression
of a particular oscillatory
frequency called
sensorimotor alpha,
or some people call
it mu attenuation.
So we know that at rest,
neurons in sensorimotor
cortex fire spontaneously
and they fire in synchrony.
And what that means is we
get these large amplitude EEG
oscillations in the
alpha frequency band.
When the motor cortex is
activated in remote motor
cortex is activated, and
that happens, of course,
when we act.
It also happens when we
watch other people act.
What you see is you see a
suppression in sensorimotor
alpha.
So many people recently
have been interested
in suppression of sensorimotor
alpha new attenuation
from the perspective of looking
at the mirror neuron system.
More broadly and
for our purposes,
we're really just
thinking about this
as a measure of sensorimotor
cortex activation.
So greater suppression equals
more sensorimotor cortex
activation.
And our question here was
whether infants activation
sensorimotor cortex
wouldn't vary
as a function of
watching people lift
blocks of different weights.
Would you get greater
activation when people
were lifting heavier objects?
Which would, of
course, be a sign
that infants were distinguishing
between different actions
on the basis of effort.
OK.
So in addition to
looking at that,
we also gave infants a
group strength assessment.
OK.
So let me tell you a little
bit about the grip strength
measure, only because it took
us several years to come up
with this so I feel like I need
to talk about it a little bit.
So we wanted to measure
infant strength, and the way
that we did that is by measuring
infants' grip strength.
But, of course,
the challenge here,
if you're an adult,
right, and you
want to measure an
adult's grip strength,
you just get something
called the dynamometer,
you have an adult squeeze a
bulb or squeeze the hand grip
and then you get this nice
force reading from that, right?
And that all works very smoothly
with adults but, of course, you
can't just hand
that to an infant
and say, squeeze
as hard as you can,
that doesn't work, obviously.
So what we did here is we had
an experimenter who had a toy,
the infant had the same toy.
The experimenter would squeeze
her toy, and what we hoped
is that this would motivate
infants, or lead infants,
to squeeze their toy.
Their toy, in contrast to
the experimenter's toy,
had both a hidden sensor
embedded within the toy, which
led to playing Old
McDonald, which, of course,
infants greatly like, right?
They find that very enjoyable.
And it also had a hidden
pressure sensor within it.
So we were able to
get-- or to measure how
hard infants squeezed the toy.
Now, the trick here was
we want to get infants
strongest squeeze, right?
So what we did is we
set up our device so
that each time the
infant squeezes it,
they have to squeeze harder
to get Old McDonald to play.
And, of course, they want
Old McDonald to play, right?
So they're motivated
to keep doing that.
So that's how we record
infants' maximum grip strength.
We like essentially keep
going as long as infants will
allow us to do that, basically.
There are some other
things that we measured.
We measured infants weight.
Our motivation for doing this
is that an adults' strength
and weight are
highly correlated.
They were in our sample so
that kind of helps to validate
or grip strength paradigm.
And there were things like
general motor maturity that we
measured, gross motor skills.
We measured how frequently
infants lift blocks
within the task, because
we want a control for these
in our analyses.
We're wanting to
look specifically
at the effective grip strength.
OK.
OK.
So let me tell you a bit-- the
first thing that we looked at.
So I'm going to show you
a series of scatter plots
that look at the relation
between sensorimotor alpha
suppression, and
infant's grip strength.
And these are
plotted as a function
of the weight of the block.
And these are when infants
are observing other people.
So the thing to know is we're
talking about suppression,
so you're looking
for negative scores.
More negative scores
mean more suppression.
And we had a
particular hypothesis
about how this would go, or
idea about how this would go.
We thought that when the
blocks were relatively light,
grip strength would be
less of a good predictor
of sensorimotor
alpha suppression.
And the reason for
thinking that is
that whether an infant is
relatively strong or relatively
weak, they all probably have
lifetime experience lifting
relatively light objects.
However, where strength
really comes into play
is as objects get
heavier, right?
So stronger infants,
very likely,
have a greater lifetime history
of lifting heavier objects.
So our prediction was
that these two things
would be increasingly tightly
integrated as block weight goes
up.
And, in fact, that's
exactly what we found.
So there's weak relations
when the block is light,
when it's that heavy block--
we call them the heavy and
the super heavy block--
there's a tighter relation.
And you see the
strongest relation here
when the block is
extremely heavy.
And these analyses
control for things
like infants in task lifting
experience, their weight,
their motor development scores.
So the next thing
we wanted to know
is we wanted to
know whether there
was any evidence that
suppression of sensorimotor
alpha would be greater in cases
in which the block is heaviest
versus the block is lightest.
So this is really our
index, or our measure,
of whether infants are
differentiating when they're
watching other people act
on objects, whether they're
differentiating the degree
of effort that goes along
with lifting the object as
a function of block weight.
So what I'm going to show
you is change scores.
So more negative
means that you're
seeing increasing sensorimotor
alpha suppression for heavy
versus light blocks,
and these are
plotted as a function of
infants' grip strength.
So what you can see here is
that for the weaker babies,
the lower grip strength
babies, you're not really
seeing any systematic
change from the latest
block to the heaviest block.
But you are for the
stronger infants.
So what these findings suggest
to us is that the stronger
infants appear to be
differentiating these actions
on the basis of the weight of
the object that the person is
lifting, the weaker
infants aren't.
OK.
So what do we know
from this data.
Well, we have some
evidence that activation
of sensorimotor cortex
as indexed by suppression
of sensorimotor alpha,
while babies are watching
other people lift blocks
of different weights,
varies as the function of the
weight of the block, right?
So this might
signal that infants
are able to recognize that
different actions have
different degrees of physical
effort that go along with them.
And we also see that the
ability to make this distinction
is tied to infants own strength,
their own grip strength.
And our interpretation
of this is
that this might have to
do with strength being
a rate limiter,
or a facilitator,
or the type of experience
that infants previously
have with objects of
different weights.
And, in particular,
the stronger infants
might have more experience
with lifting heavier objects.
They might have more
contrastive experience, which
allows them to better recognize,
or better differentiate,
the degree of
physical effort that
go along with
different actions when
you're talking about lifting
objects of different weight.
OK.
So that's part one.
So I think what these data tell
us is that in this context,
infants have a
means of registering
effort related costs.
I think where they go above
past data is that they tell us
that infants can do this
under conditions in which they
have minimal behavioral cues.
So we think back to that
reaching action, right?
There's all kinds of cues that
this is a costly action, right?
There's all kinds of ways that
it differs from a direct reach.
In this situation, we're
talking about actions
that are really minimally
different from one another.
What I want to do now is I
want to switch gears and talk
about kind of the
flip side of the coin.
And that is infants use
of costs and benefits,
or reward, to guide
their own behavior.
And I'm going to be
specifically focusing
on the test case of
infants prosocial behavior.
So many of you may
know this already,
but infants are highly
prosocial, right?
There's been a lot of
studies on this recently,
and all of these
studies have kind of
come down on the
conclusion that starting
in the second year
of life, infants
will do things like help
people achieve their goals,
they will share toys or
objects with other people,
they're comfort
people in distress.
But there are
questions and debates
that are hotly contested about
early prosocial development,
and I just want to bring two
of them to your attention.
OK.
So one question is, when
does infants or children's
prosocial behavior become
selective or strategic, right?
So we know that
by preschool age,
early school age, children's
prosocial behavior
is somewhat selective,
meaning that there
are some people, for
example, that infants
are more likely to help
than others, right?
And children are-- not
infants, children-- children
are more likely to
help under situations
where they are perhaps
reputational concerns involved.
But what we don't yet
know is whether this
is true of very early
prosocial development.
So what is the
developmental course like?
Do kids start off being
selective and strategic?
Or do they only get there
over time with development?
That's one question.
There's another
related question that
has to do with what is
the underlying motivation
for prosocial behavior, right?
So the kind of
generous interpretation
of infants prosocial is actions,
children's prosocial action,
is what is going on here
is infants are motivated
by empathic concern, right?
They care about
other people's needs,
they care about other
people's desires.
And in these
experimental context,
what they're doing is they're
acting to meet another person's
needs, they're acting
out of empathic concern.
But there's also other reasons
why infants, or anyone,
for that matter, might
behave prosocially,
that might have to do
with social affiliation
biases, social motivation,
that might have
to do with wanting to see
a goal being completed,
et cetera, right?
So one of the ways that we
can start to get traction
on these issues is by looking
at the impact of various costs
on infants' prosocial behavior.
And somewhat surprisingly, this
is not a terribly well studied
topic as of yet.
So there are some studies
that are both with infants
and with children,
where people have looked
at the impact of personal
cost on prosocial behavior
and, usually, the way personal
costs are operationalized
is in terms of,
let's say, an infant
is tested in a paradigm where
they need to help someone else,
or share an object
with someone else.
And they might be
required to give up
their own object versus an
object that's just sitting
there in the lab, right?
Presumably, their own object
has higher personal cost.
Now, we don't really know
when personal costs start
to impact infants'
prosocial behavior,
because there's been a
lot of mixed evidence.
And, particularly, in
infancy, there's, as of yet,
no systematic evidence that high
personal costs actually reduce
infants' prosocial responding.
What about the question of
energetic physical effort
related costs?
Well, again, here, this is
really an understudy topic.
So there's one
existing study that
has looked at infants
helping under kind
of minimal physical effort cost.
And it's a little bit hard to
know what to make of that study
because we know that
infants helping behavior
is still present under
those conditions,
we just don't really know
how it compares to conditions
where the physical
costs are low.
OK.
So we started off by asking a
really super simple question
about infants
prosocial behavior,
and that was whether the
anticipated physical effort
that goes along with
prosocial responding
influences infants
prosocial responding.
In particular, when the effort
is high, does it increase,
or rather, decrease
infants prosociality.
OK.
So we tested 18-month-old
infants in this study.
Start by telling you about
the critical test phase,
it was a helping task.
An experimenter was on the
opposite side of the room.
She needs a block
in order to complete
a tower that she's building.
What happens before
that is all infants
take part in a training phase.
They're faced with
these vinyl blocks.
You'll see a video
clip in a moment.
And these vinyl clocks have--
blocks have been rigged by us
so that they range in weight.
There's five of them,
they're different colors,
so infants can
keep track of them.
During training, what
happens is the experimenter
plays a game with
an infant where
they get them to drop
each block into a bucket.
Babies like to do that, it
makes a cool noise, right?
And, really, this training
phase serves two purposes.
The first purpose
that it serves is
we want infants to learn
how much each block weighs.
The second purpose
that it serves
is we want to be
able to record what
is the heaviest block that
infants are capable of lifting.
All right.
In the test phase,
as I told you,
the experimenter's on the
opposite side of the room,
she's building a
block tower, she
needs a block to complete it.
There's a single target block
available to infants and what
varies between
our two conditions
is the weight of that block.
So for half of the babies, the
lightest block of the training
blocks is left behind.
And for the other
half of the babies,
the heaviest block that
infants are capable of lifting
has been left behind.
So we're contrasting
effort here in terms
of the weight of the
block that infants
have to carry across the room
to help the experimenter.
So we're looking at
infants block retrievals.
The other thing that we
recorded was a parent report
of infants walking experience.
So these are 18-month-old
infants, they can all walk.
On average, they've been
walking for six months
so they're all
experienced walkers.
But there's
individual variability
in terms of how long
they've been walking for.
So why was this important?
Well, here was our
underlying logic.
Imagine that you and a
friend are going on a hike,
you're both equally strong,
you can both lift 60 pounds.
But your friend
is an expert hiker
and you're a novice
hiker, right?
And you both have to carry a
60 pound backpack up the hill.
Well, despite the fact that you
might both be equally strong,
if you're the
novice hiker, that's
probably going to be
more effortful for you
to get that backpack up the
hill than it is going to be
for your friend or your buddy.
So we had a
particular prediction
that what we would see is a
relationship between parent
reporter walking experience,
and infants likelihood do this--
likelihood to help the
experimenter by carrying
the block across the room, and
that this would be selective,
or at least stronger, for
the high effort condition.
OK.
So let me show you a
couple little video clips
here so you can get a
flavor of the procedure.
This is just showing
you the test phase,
so it's exerted
from the test phase.
There's one thing I want
to explain a little bit.
So you can see up here there's
this striped bucket here.
And the reason
that we have there
is-- that there is because we
want the experimenter to be
unaware of the target
block that is left behind,
so they're naive to
the infant's condition.
It looks like from the infants'
perspective that they can see
the target block, but
they actually can't.
They don't know if they're
in the high or low effort
condition.
So this is the baby who is
tested in the low effort
condition.
[VIDEO PLAYBACK]
I'm going to use these
blocks to make a tower.
These blocks can go here.
This one can go here.
And this block can go--
oh, no.
Oh, no, I'm missing the block
I need to finish my tower.
I'm missing my block.
Ah, oh, there it
is, Joelle look.
The block got moved
on your blanket.
Can you bring me the blocks
so I can finish my tower?
[END PLAYBACK]
All right.
Sorry, we exerted
a little bit early.
He goes over and he
gives her the block.
OK.
OK.
Now let's watch a baby in
the high effort condition.
Remember, the only difference
between these two conditions
is the weight of the block
that's been left behind.
OK.
[VIDEO PLAYBACK]
I'm going to use these blocks
to make a tower These blocks can
go here.
This one can go here.
And this one can go--
oh, no.
Oh, no, I'm missing the block
I need to finish my tower.
I'm missing my block.
Ah, oh.
There it is, Rose.
The block got left
on your blanket.
Can you bring me the block
so I can finish my tower?
[LAUGHTER] Can you
bring me the block?
Rose, can you bring me the
block so I can finish my tower?
No.
[END PLAYBACK]
So it's a little hard to
hear what she was saying,
but if you couldn't hear it,
she was saying, no, thank you.
So she said, no.
No, thank you.
No, thank you.
OK.
So that's a-- pretty
illustrative of the procedure.
OK.
So what did we find?
So here's infants' rates of
helping in the low effort
condition.
In the high effort
condition what you can see.
So infants help
much more frequently
in the low effort condition
than in a high effort condition.
Here's what we
found with respect
to infants' walking experience.
A walking experience, how long
an infant has been walking
predicts infants' likelihood
of helping in the high effort
condition.
And what this tells us
is that for each month
of additional
walking experience,
infants are twice
as likely to help.
Now, what we can see
here is that infants
are less likely to help under
high effort conditions, right?
So infants prosocial
behavior is influenced
by the effort related costs
of prosocial responding.
And a critic, I
guess, could say,
well, maybe it's that--
it's not that infants
are going by the
effort, it's maybe
that they're not able to help
in the high effort condition.
We don't think that that's
the case, because infants have
given us evidence that they're
capable of lifting that block,
right?
That they're later-- later
tested with in the high effort
condition.
But the next condition
I'll show you
will also kind of speak to that.
And the important--
another important thing
to recognize here
is that infants
seem to be recognizing these
costs at an objective level.
I think Laura called
this in her talk an agent
independent level, right?
As a function of the
circumstances of the situation,
right?
And they're also
recognizing costs
that at a more
subjective level in terms
of their own
capabilities and how that
influences the particular cost.
In this case, it's their
amount of walking experience,
how expert a walker they are.
OK.
So what we wanted to
do next is to find out
whether if when
infants are presented
with these high effortful
helping situations,
whether infants
helping behavior would
vary as a function of
the motivational benefits
of prosocial responding.
Now, it's been pretty
firmly established
that early prosocial
responding appears to be
immune to extrinsic rewards.
So what that means
is if you test
a baby in one of these
helping paradigms
and you say, good job,
way to go, good job.
That's actually not
going to increase
their subsequent
helping behavior.
If anything, it
will decrease it.
But that doesn't mean that
more intrinsic rewards
don't influence
how infants perform
on these particular tasks.
We know from some prior work
that infants by this age
have certain affiliated
biases, right?
They have biases
for individuals who
share their preferences,
who share the--
who like the same things
that the infant likes.
They prefer to play
with those people who--
than people who don't like
the same thing that they like.
And they also have-- possess
affiliated biases for people
who could be--
said to share sort of in-group
member characteristics, right?
So infants, like
people who speak
in native-- their
native language
over a nonnative
language speaker.
And, of course, these
affiliated biases
might have important
functional consequences, right?
They might be important
for cultural learning.
So what we wanted to
know in this next study
is whether we could kind of push
around these intrinsic benefits
for infants to see if
their behavior would
change under these high
effort helping conditions.
The way that we did this
in this particular study
is prior to the test
procedure, the helping task,
we had infants take
part in this little task
where they were given one--
two toys.
They could choose
between the two toys.
This happened on three
different trials,
different toys each trial.
Infants would make a choice.
And then the experimenter
would subsequently
show that she liked one toy
and disliked the other toy.
And the really
simple manipulation
between these two
different conditions
was whether the experimenter
liked the same toy as the baby,
or whether she
liked the other toy.
So did she share the
infant's preferences,
or did she oppose their
preferences, right?
And we would think
in terms of the data
on infants affiliative
biases, that they
would prefer to
interact with someone
who shares their preferences.
Infants took part in
the same helping task
as they did in the
first experiment.
To streamline the procedure,
we used the medium block weight
that infants have been capable
of lifting in the first study.
The other thing that we did
is we added a post-test phase.
So we excluded any
infants who were not
capable in the post-test
of lifting the target block
or a heavier block, right?
So we know for all of
these infants in the sample
that they can lift the block.
The question is, do they
help the experimenter.
OK.
So we again looked at
infants' helping behavior,
we looked at their
walking experience.
The other thing that
we did in the study
is we looked at infants helping
as a function of the response
period.
Whether helping
occurred in the--
rates of helping in the first
half of the response period
versus the rates of helping
overall in the response period.
And our motivation
for doing this
is that we thought that
if there are differences
in the degree of
motivation to help,
you might see early differences
in the response period, right?
So early on, infants
might differentiate
across the conditions.
But these might
attenuate over time.
One thing I forgot to
mention is that in the course
of the response
period, infants receive
prompts at certain
intervals in order to say,
can you get me the block, right?
So the question is
with these prompts
will any early differences that
we see attenuate over time?
OK.
So here's what we can see.
This is the first half
of the response period.
Infants in the shared
preference condition
are significantly more likely
to help the experimenter
than infants in the nonshared
preference condition, right?
So when there are intrinsic
rewards associated
with engaging in
high effort behavior,
infants are more likely
to help the experimenter.
And the other thing
that we saw is
that infants walking
experience significantly
predicts helping behavior in the
nonshared preference condition.
So when the motivational
benefits are low,
these subjective costs
seem to exert a stronger--
a stronger role, have a
stronger predictive value,
than when the motivational
consequences-- or, sorry,
motivational benefits are high.
And then here, this just shows
you infants' helping behavior
but, now, as a function of
the overall response period.
You can see they're still
numerically different,
but they start to
come together, right?
So the differences
are really driven
by what's happening early
in the response period.
OK.
So these findings suggest
that infants willingness
to engage in high effort--
high cost helping is
motivated or affected
by intrinsic
motivational factors.
Infants are more likely to carry
a heavy block to help someone
who shares their preference.
One thing I want
to point out here
is that these findings
help us sort of
interpret what's going on in
the first experiment, right?
If the first experiment
was explained by the fact
that it's a lack of ability
versus a lack of effort,
we shouldn't get
these findings, right?
Because the effort is equivalent
across these two conditions
here.
And what simply varies are the
kind of motivational benefits.
OK.
So, now, I want to
tell you about a study
that we're just in the
middle of conducting.
I think it's really
exciting and interesting.
I'd be curious to
get your thoughts.
So we're literally
mid data collection,
but I think I have
enough data to tell you
what's going on so far.
So, now, we're trying to
expand the scope of benefits
that we're looking at, right?
And as we sort of
alluded to earlier,
we don't-- really
don't know as of yet,
or we don't know very much,
about what cost counts
as a cost and a benefit
for infants, right?
That's something
that we actually
have to figure out to
determine empirically.
There's been some
recent studies that
have shown that three- and
four-year-olds, perhaps
paradoxically, when they're
tested in sharing tasks,
are more likely to share
with a rich recipient
than a poor recipient, right?
And that is paradoxical in
the sense that, of course,
the rich recipient has less of
a need than the poor recipient.
But, perhaps,
unsurprising in the sense
that there's something
self-serving, right,
like it might be in your
self-interest to affiliate
with people who have a lot
of resources versus people
who have few resources.
In our study, what we did, is
before infants got the helping
task, we demonstrated to
them that one individual
had more resources than
the other individual.
It's a really
simple manipulation.
What they did is they
saw two individuals are
sitting at a table.
They both had these like
transparent fish bowl looking
balls, and on each trial
they have different goods
in the fish bowls.
So what happens is that
one individual always
has lots of stuff, right?
On one trial it's animal
crackers, the other trial
it's these cool little balls.
The third trial it's these cool,
flashing little blingy rings.
And the other
person has very few.
But they both do
exactly the same thing
during this first phase.
What they do is
they take turns--
we counterbalance
everything, of course--
they pull out three
objects one at a time
and, they say, hey, baby,
look at all my toys, right?
So they're both doing the same
thing, exactly the same thing.
What differs is the kind of
resource contacts, right?
One of them has a lot of stuff.
One of them only has
three things, right?
And we do that on
repeated trials,
because we're trying
to give babies
the impression that,
generally, this person has more
stuff than the other person.
OK.
So then we test infants
in the helping task.
This helping task is a little
bit different than the one
I just told you about,
because now we're
pitting these two experimenters
against one another.
The experimenters in the helping
task have equivalent need.
They both, like Miranda
was doing earlier,
are building this tower, right?
They're missing a
block, they need a block
to complete their tower, right?
The only thing
that differentiates
the experimenters is
what happened previously.
One person had a lot of
stuff, the other person
didn't have very much stuff.
And the other thing that
we're manipulating here
is whether the
infant has to engage
in equally effortful actions
to help the two experimenters,
or whether helping one
of the experimenters
is more effortful.
And the way that we've
operationalized this so
far in this study is by varying
how long the baby has to walk.
So, in one case, the person
is within a few feet,
in the other case,
they're across the room.
OK.
So let me show you the data,
first, for the equal effort
condition.
So these are-- this is--
what this graph shows you
is who the baby is helping.
And what you can see here is
when effort is equivalent,
infants are systematically
helping the person
who has more resources.
They're helping the rich
experimenter, right?
So now the question
becomes, what
happens in cases
of unequal effort?
And as I said, this
data is still coming
and we're still testing
this, so the condition
that we started with, given that
we have this initial pattern,
is the condition where the rich
experimenter is the one you
have to walk a long way to.
And the poor
experimenter is the one
you have to walk a short way to.
And here's what we see.
It flips.
So I think what this suggests is
that infants are both weighing
the costs of the action
they have to perform,
and the intrinsic motivational
benefits as defined
by these sort of
things that might
be important for
social affiliation.
OK.
So what implications
does this have
for infants' prosocial behavior?
Well, it suggests that
it may be the case
that cost benefit
analyses underlie
infants prosocial behavior.
In particular, their
helping behavior.
And I also want to take us
back to two of the questions
that I raised earlier.
One was about the
selective nature
of early prosocial behavior,
the strategic nature.
And the other was about
the underlying motivation.
So think in terms of the
selective strategic question,
on the one hand, we can say,
fairly early on at 18 months,
infants' prosocial behavior
is strategic in the sense
that what they
seem to be doing is
minimizing costs and maximizing
motivational benefits.
And in terms of
the motivation, I
think what these
findings tell us,
and this is not to say that
infants are never motivated
by empathic concern,
they're never
motivated by other
people's needs,
but there are other things
that come into play here.
So infants' underlying
motivation to help
is influenced by a tendency
to want to affiliate
with particular individuals.
OK.
So I told you a little bit about
infants registration of costs
in the actions of other people,
their use of costs and benefits
to guide their own
prosocial behavior.
I just want to close by kind of
raising some questions that I
think we should be interested
in pursuing in the future.
OK.
So this came up earlier, right?
So one thing that we
have to understand
to understand
infants' behavior is
to understand what acts
as a cost for infants
and what acts as a
benefit for infants.
And I think the thing that's
really important to point out
here is it won't necessarily be
what we think as adults, right?
It won't be intuitive
to us, right?
And the classic
example that we can
think about is, you know,
you buy your child this toy,
you bring it home
from the store,
you're so excited to give your
child this cool snazzy toy,
and all they want to do is
play with the box, right?
So what that shows us is we're
not good models, necessarily.
We have to kind of
determine this empirically.
We can't necessarily use our own
intuitions to figure this out.
Another question is how
are costs read, right?
So in the first
study I showed you
that infants' experience
potentially is important,
or factors that gait
infants' experience, right?
But that's in a
situation where there
aren't a lot of
observable cues to effort.
So I think it may be
the case that there's
some variability here.
Some costs infants
may require experience
with in order to figure out
what is the cost, right?
How much of a cost is this?
And maybe there are other costs
that infants can more readily
read from the get go.
And then, finally, I
think at some point,
we need to ask whether
infants and, potentially,
children are sensitive to other
types of costs beyond effort.
Also, if they have a kind of
higher level category of cost.
So one thing that's really
interesting in the literature
on nonhuman animals
is that there are just
so simple neural systems
that are responsible
for effort reward
decision-making,
and for delay reward
decision-making.
But, obviously, we, as
adults, can group these things
together, or I wouldn't be
able to give this talk today,
and Laura wouldn't have been
able to give her talk today.
So one of the things we
have to start to understand
is when did those things
kind of come together
in service of this
larger category of cost.
OK.
So I'm going to stop there
and ask for questions.
