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ALIA MARTIN: I'm going to be talking today
about how infants and kids start to develop
an understanding of communication
and why this is an important topic for understanding
human intelligence.
So what is communication?
So really, basically, communication
is a transfer or exchange of information.
And importantly, in human communication,
this isn't just any kind of information,
but it's specifically the kind of information that's
in our heads and in our minds.
So for example, there's information in my head
right now that I'm going to be transferring to you
over the course of this talk.
And the reason we need communication to do this
and that we use it all the time is obviously
that everyone has minds of their own
and that we don't have access to the mental states of others.
And we can't automatically transfer our own mental states
to theirs without some means of making those mental states
observable in the form of communicating with them.
So people are both cognitive beings--
we have to sort of navigate the thoughts in our heads and try
to figure out the thoughts that are in other's heads--
but we're also social beings.
We really benefit from gaining access
to the thoughts in the minds of others
and giving them access to our own thoughts.
So for example, for cooperation, competition, learning,
and teaching, and all the kinds of social interactions
we do with each other, we have to be
able to share the contents of our mental states.
And it's this sort of joint, both cognitive and social
nature of communication that I think
makes it especially important for understanding
the development of human intelligence.
It sort of crosscuts a lot of these core knowledge
domains that Liz talked about in her talk.
So human communication requires reasoning
about others' cognitive states, so
understanding what others' beliefs, and desires,
and intentions are.
It also requires reasoning about social interaction,
so understanding that typically these kinds of thoughts,
and beliefs, and intentions are not
shared among different people.
Everyone has their own that are unobservable
and housed in their own heads.
But in the context of a particular kind
of social interaction, these people
can intentionally share their thoughts with each other.
And communication often involves reasoning
about a third thing, which is language or communicative
signals outside of language as well.
And so I'm going to back to this point at the end,
but all these types of reasoning are
going to come up in the studies about infant communication
that I describe in the talk.
And so Liz talked about how infants start out
with these coherent, separate, principle, and core knowledge
systems that contain some limited representations
for reasoning about the world, and which kind of come together
around the end of the first year.
So if we want to figure out how to build a model of how
social cognitive development works,
we're going to need to understand how an infant starts
to figure out, using the core knowledge
that they have early in life, the components of communication
and also how these components come together so that infants
can build a more complex causal model of communication
like adults have.
So this is just to illustrate the points
I'm making about the communicative situation.
So in any given communicative situation,
we can't just think about the words that are being said
or what we're hearing.
We need to think about it in this broader context of having
a communicator or maybe multiple communicators, an addressee
or an audience, and also the things that the communicator is
saying in the broader context that
allow us to figure out what's going on
in this social interaction.
So it really requires understanding
that the communicator's mental states are
being transferred in this causal way
to the mind of the addressee.
So I'm going to structure the talk in terms
of some important insights from the philosophy
of human language and communication
that I think have really guided the way
researchers in the last, say, 50 years have
been thinking about the development
of human communication as well.
So I'm going to broadly illustrate the three points
that I'm taking from each, and then I'll expand on them
in each section.
So the first insight that I think
is really important for understanding
how we think about communication comes from John Austin, who
brought up the important point.
So before Austin, people tended to think
about language or study language a lot in terms of language
itself, and the semantics, and syntax, and just the language
signal.
But Austin pointed out that language is actually
not just about the content, but it's also an action.
It's actually something that we use, and we do things with it,
in the same way that we do things and accomplish things
in the world using other kinds of actions that we engage in.
So Austin sort of brought up this important distinction
that language is not just about the content.
So to illustrate with an example,
in this communicative interaction,
there's language here.
This person is saying, is there any salt?
And Austin analyzed this in terms
of not only what the words meant,
but in terms of three layers of intentionality.
So in this simple interaction, he pointed out
that there's a locutionary act, or the meaning of the sentence,
which is that there's a question being asked
about the presence of salt. But that there's
actually something else going on here
as well, which is that there's an illocutionary action, which
is what he considers to be the intention underlying
the action, which is to request the salt.
So if you actually just read this sentence,
it's kind of under-determined.
It's not necessarily obvious that this person's
asking the other person at this table to pass the salt.
But if you take it within the broader
context of the interaction, you can understand
that what's really going on here is not just a sentence being
produced, but rather one individual requesting something
from another, who is then supposed to understand
the request, and in the third layer of analysis,
cause the addressee to provide the salt.
So the idea is that there are these multiple things going on
in the context of a communicative interaction
involving language that go beyond the words that
are actually being spoken here.
And so if you're an infant, just like in philosophy of language,
the focus in infant cognitive development--
also for a long time, and still is,
we still need to understand these things--
was on understanding how infants learn words,
or how infants figure out the meaning of language,
and how it relates to objects in the environment,
and later, to the abstract concepts
that language indicates.
But importantly, understanding communication for an infant
is going to be more than about just figuring out
the meaning of these words.
And so following the philosophical tradition
of people like Austin, who introduced
the study of pragmatics to language,
developmental psychologists as well
started thinking about the importance of recognizing
communication as this broader action in its context
for understanding how infants come to be good
communicators themselves.
So if communication involves this whole context of action
and interaction between people, if you're
a baby who's in the business of understanding
the social world, the agent world, and the world
of language, you're going to be well-served by developing
an ability to identify these kinds of communicative actions
or situations and their components,
and to begin to understand how they work.
So how do infants start to figure out
when communication is going on in the world around them,
rather than just identifying words and associating them
with objects?
So actually, there's a lot of evidence
that infants are identifying key features
of communicative situations really early in life.
So from the time they're born, newborn human infants
prefer listening to speech over other sounds.
So the typical method that's used
to measure the preference of an infant who's
only one to four days old is to have
them suck on a pacifier that's connected
to a machine that detects how strongly infants are sucking.
And then the sucking is used as a measure of infants
arousal upon hearing a particular sound
or being exposed to a particular stimulus.
And so what researchers found is that if you have infants suck
on this pacifier while listening to speech
sounds and nonspeech sounds in alternation,
nonspeech sounds being sine wave-produced sounds
that are very similar to speech in their features.
If you listen to it, it has the prosodic contours of speech
and sounds a lot like it, but it's not actually speech.
You can't actually parse any words from it.
Infants showed a preference for listening
to speech over nonspeech, or more arousal
when they listened to speech.
So they maintained their arousal for speech
over the course of the experiment,
but for nonspeech, it declined.
And so extremely early in life, infants
seem to have this bias for paying attention
to the primary communicative signal of our species, that is,
human speech.
Quite early in life as well, infants
recognize some of the important features of the social context
surrounding speech, so getting more
into the domain of the important features for communication.
So by six months, infants seem to recognize
that speech is human-produced, or at least
associate speech with other humans,
and also human-directed.
So in one study, infants saw pictures of human faces
or faces of monkeys, and they heard different sounds.
So they either heard--
oh, it seems like the sound is not on, but that's OK.
So they either-- oops.
So they either heard a speech sound in a language
they never heard before repeating itself,
or they heard a monkey call.
And infants in one trial either saw-- so in the first trial,
say, they'd see the human face, and then they
could listen repeatedly to a speech sound
until they looked away for two seconds.
And then they would see a monkey face,
and then they would hear either a speech sound or a monkey
sound and be able to look at this image
while listening to that sound until they looked away
for two seconds.
And so they got all possible combinations.
Sometimes they saw a human face and listened to speech.
Sometimes they saw a human face and listened
to the monkey sounds.
And sometimes they saw the monkey face
and listened to either human speech or the monkey sound.
And the question was whether infants actually
could match speech sounds to humans
and recognize that they should be produced by the human rather
than the monkey.
And that's what they found.
So you can see that when infants heard speech,
they were much more likely to look at the--
yeah, they were looking at the human when they heard speech,
and then they were looking at the monkey
when they heard the monkey calls.
Similarly, infants seem to understand by six months
that speech is directed at other humans.
So when they saw a person talking
behind a barrier versus acting, so
swiping with her hand behind a barrier,
and then the barrier was revealed
to reveal either a person or an object,
infants looked longer for the speaking familiarization
when they saw that there had been
an object behind the barrier than a person,
suggesting that they expected speech
to be directed toward another person.
And in contrast, when they saw the person swiping,
they looked much longer when they saw a person
behind the barrier because typically, we
don't swipe at people.
We tend to speak to them.
So this suggests that infants understand
some of the features of the context
in which human communication is produced.
Importantly, infants do still seem
to be developing this ability over the first year of life
because it's not until 10 months that they expect
mutual gaze between speakers, which
tends to be an important part of understanding
the social context of communication.
So in this study, infants saw two people facing each other.
This is just one of the experiments from the study.
But you can see that they saw the two people looking
at each other and speaking to each other,
or the two people looking apart and speaking to each other.
Infants at nine months didn't differentiate
between these at all.
So at nine months, they didn't necessarily
think that the people were going to look at each other
when they were speaking.
But at 10 months, you can see here
that infants looked longer for the averted gaze
than for the mutual gaze.
So infants seem to be able to recognize
when a communicative context is going on early in life.
But we don't necessarily know from these studies
whether they really understand that communication is happening
or whether they're just detecting
some important features of communicative interactions
that might help them to glom onto communication so that they
can eventually develop an ability to figure out
what's going on within the communicative interaction
themselves.
So, so far in the studies that I've mentioned,
there's nothing cognitive here.
There's nothing really about infants
having to understand the intentions or the mental states
of the speaker going into the mind of the addressee,
like I was talking about before.
So a question I've explored in my research
is whether infants recognize that when these features are
in place, when you have a communicative signal, which
is something they recognize, when
you have a communicator and addressee who
are socially engaged with each other,
do infants recognize that communication can actually lead
to the transfer of information?
So do infants understand that speech, using speech,
because this is something that infants seem to recognize
as a signal that's important in communicative context,
can transfer information between individuals?
So we can use speech to communicate with each other
about what we're interested in.
So if I'm observing this interaction
between a communicator and an addressee,
I can infer that if the communicator says, the cup,
and there's only one cup present,
the addressee's probably going to be
able to figure out what it is that the communicator wants.
And I can figure this out even from a third party perspective.
And I can also understand that other kinds of sounds,
like perhaps a positive emotional vocalization,
are not going to be as effective in communicating
to the addressee what the communicator is interested in.
So speech and also other communicative
signals as well that can specify this sort of information,
perhaps like pointing or particular kinds of gestures,
can transfer information from one individual to another.
So speech is going to be more effective for communicating
than other kinds of noncommunicative actions.
And importantly, for the purposes of this study,
you're not just going to know that communicative information
transfer is going on because you know what the word cup means,
even in a situation where you're listening
to a foreign language, and you have no idea what
the meaning of the words are.
Even in this situation, you're going
to understand that some kind of communicative information
transfer can happen.
So we've all had the experience of being in a foreign country,
presumably, where you're listening
to people speak to each other.
You can't necessarily understand what they're saying,
but you know that information transfer is happening.
So the interesting thing about communicative actions
like speech is that when we witness them,
we can know that people are communicatively
sharing information, even when we
don't know what information is being communicated ourselves.
And this insight suggests that maybe,
if you're an infant, one really good way
to jump into the communicative interactions around you
and start to understand what's going on
is to be able to identify when others are communicating.
And hearing the sounds of speech exchanged
between two people in the context of a social interaction
might be a really good way to do this.
So an ability to figure out when communication's going on
like this might provide infants with this really powerful way
of being able to track the information flow between two
other people's minds and also to figure out,
based on their responses to each other, what
the actual content of the words might mean.
So we asked whether infants recognize
that speech is communicative at 12 months of age.
And so in the procedure of this study,
infants were privy to a third party
interaction between a communicator and an addressee.
And the infant is always just observing the interaction.
This is so that we can isolate whether infants think
that certain communicative vocalizations can transfer
information from the communicator to an addressee,
even when the infant themselves has all the information.
So the third party nature of this procedure
is important here for seeing whether infants really
are thinking about the fact that thoughts are typically isolated
in particular people's minds, but with communication, they
can be shared.
So infants in these studies were given a violation
of expectation paradigm.
In this kind of experiment, as many of you probably know,
infants are shown a story through a series of scenes.
And then in the last scene or series of scenes,
they're shown different kinds of endings.
And we're interested in whether infants are surprised or look
longer at some endings more than they do at others.
So infants in these studies were shown a live display
where they had an actor in front of them in a stage.
First, they were familiarized with this actor showing
a preference for an object by picking it up and playing
with it repeatedly in three separate scenes.
And so, as in the studies by Amanda Woodward that Liz
already mentioned, infants, by 12 months
and as early as three months, will attribute a goal
to this person for reaching for that particular target object.
So after being familiarized to this,
infants saw an addressee, who was a new person,
present in a totally different part of the stage.
They had never seen this person before,
and they'd never seen the two people together before.
This person reached for both objects in turn.
So first, she grabbed this one, then this one,
and then this one, and then this one again
to show that she didn't have a preference between the objects
and could reach both of them.
Then in the test scene, so this is the ending
that we showed infants, they saw the two people together
for the first time, but now the communicator
couldn't reach the objects because only her face had
access to the stage.
But the addressee could still reach them just fine.
At this point, the crucial manipulation
was the vocalization uttered by the communicator.
So she either produced a speech sound, the nonsense word koba,
which infants had not heard before, she produced
a coughing sound, so something that would typically
be physiological and not intentional or communicative
in any way, or an emotional vocalization, so a sound
that perhaps could convey information.
If I say, ooh, you might think I'm interested in something,
I'm feeling positive, but you won't necessarily
know what it is.
So this one's sort of in the middle of the other two.
And then, infants saw the addressee either
provide the target object that the communicator had
reached for before or the nontarget object.
And the question is, do infants understand that speech
as a communicative signal, do they have some expectation
that even though they've never heard this particular speech
sound used before, that speech can transfer information such
that the addressee will now be able to select
the correct object?
Whereas nonspeech vocalizations like coughing and emotional
vocalizations can't.
So if so, infants in the speech condition
should look longer to nontarget than target actions, responses,
finding these unexpected.
And infants in the other two conditions
shouldn't differentiate between the two.
And this is what we found.
So in the speech condition, infants
are looking longer to nontarget than target,
suggesting that they understand that speech
can transfer information about the communicator's goal.
But when the communicator coughs or produces
an emotional vocalization, infants
don't show these same expectations.
So this is some initial evidence that by 12 months,
infants not only recognize the context in which communication
occurs and attend to speech as a special signal
for communication, but they also understand
that speech is something that's able to transfer information
between two people.
So we also ran a few control conditions
to rule out alternative explanations for this.
So one important question is, are infants really reasoning
about the addressee's access to information in this situation?
So for example, in the case where the--
if infants are really reasoning with the addressee's access
to information, then in a case where the communicator makes
a positive emotional vocalization,
and the addressee has previous information about what she's
interested in, so for example, if she just
saw that the communicator was trying to feed her child
or wanted a drink of water, she might know now
that a positive emotional vocalization is indicating
something like the cup.
So we set up a scenario like this as well.
In this case, it's exactly the same as the previous study,
except that the addressee had visual access
to the communicators preference during the familiarization
phase.
So now she knows what it is that the communicator likes.
And this is important for making sure the infants recognize
that something like visual access
can provide the addressee with information
about the communicator's interest.
So now infants saw the same addressee familiarization.
And then in the test, they saw the communicator
produce the vocalization ooh once again.
So now even though ooh was not treated
as a communicative vocalization in the previous studies,
if infants are reasoning about the kinds of information
that the addressee has access to,
they should now expect that the addressee will provide
the target object because she knows
from a previous scene what the communicator was interested in.
So this is important also for ruling out the possibility that
maybe just hearing these noncommunicative vocalizations
surprises or confuses infants or makes
them unable to reason about the scenario anymore.
Here, they're getting a noncommunicative vocalization,
but the addressee has access to information.
And here, as in the speech condition,
infants looked longer at the nontarget outcome.
So this is just some evidence that infants are really
thinking about the idea that relevant sources
of information, such as a communicative vocalization,
but also prior visual access, can
give the addressee information about the communicator's goal.
So they are reasoning about information access.
Another important question is, are they really thinking
about the source of information, or do they
have-- so what's really the mechanism behind what infants
are doing here?
Are they thinking something like, when I hear speech,
everything will go well, or the speaker
is going to get what she wants?
Or are they really thinking about communication
in this causal way, where the information has
to come from the speaker and be delivered
to the listener in order for it to work?
So to test for this, infants saw another communicator
familiarization.
Here, the communicator is alone, so they've never seen the two
people together before.
She reaches for the target object.
Then they see the addressee again.
And then in the test scene, in this case,
the addressee is the one who produces the speech.
So speech is present in the scene as it was before,
but it's not being produced by the communicator or the person
who showed a preference.
So if infants just think that speech
leads to people obtaining their goals or magical outcomes
happening, then they should expect the addressee
to provide the target here as well.
But if they understand that they don't know anything
about the addressee, in which case, this is not
really informative about either object,
then they should look equally to both outcomes.
And in fact, this is what they do at 12 months.
So infants here don't expect information
to be transferred from one person
to another, unless the first person who communicated
is the one who actually had the information to provide.
So by 12 months, infants seem to recognize
that speech is communicative, and they
seem to have some of the parts of a causal model
of communication.
They're not just thinking about speech
as something that can produce successful outcomes,
but as something that can be used
to have information move from the mind of one individual
to another.
So a 12-month-old seemed to recognize
that speech is communicative.
But we really wanted to get at the idea
that understanding that speech is communicative
might be something that drives and guides
word learning and language acquisition, rather
than something that is as a result.
So what a 12-month-old could be doing in this study
is hearing the word koba, associating it with the object
that the communicator had reached for,
and then thinking, OK, that one's the koba,
so that's what the addressee should reach for.
But in these studies, we were interested in whether infants
at an even younger age, who would be very, very
unlikely to be associating the word with the object
or learning a label for the object over the course
of the study, would also recognize
that speech can transfer information about one person
to another person.
And so for this reason, we tested 6-month-olds,
because 6-month-olds understand only some very, very
common words in their environment
and will look to the right object
when they hear the label for it.
But these are very, very limited words,
and there's no evidence for learning
a word in a single trial, which is what they
would have to do in this study.
They would have to hear koba, and then think back
to what the communicator had reached for,
and really learn that word over the course of the study, which
we have no evidence that a 6-month-old can do.
So the goal of looking at this age group
was to see whether infants might have
a more abstract understanding of the idea that when speech
is produced, information can be transferred from one person
to another, even when they themselves
don't know what that information--
or what the link between the word and the object.
So a 6-month-old saw the same scenes.
We gave them the speech versus cough contrast.
And they look the same as the 12-month-olds here.
So you can see that in the speech case,
they're looking longer for the nontarget outcome.
And in the cough case, they're looking
longer for the target outcome.
And so we haven't done all of the same control conditions
as with the 12-month-olds here.
So I think there's a lot of room for questions about how
a 6-month-old's understanding of communication
in this causal way more limited than the understanding
of 12-month-olds.
Would a six-month-old think that if speech
was produced by a loudspeaker or by the addressee,
that the communicator would still get the right object?
So there are a lot of open questions about--
these basic questions about how infants' understanding
of communicative information transfer starts out.
So these experiments suggest that by six months,
infants seem to understand that speech is communicative,
in addition to the other studies that suggest
they understand some of the features
of communicative interactions.
They recognize that it transfers information
from one person to another.
And I'd like to argue that this might
be something that provides a mechanism for language
and knowledge acquisition, so sort of guides infants
to the kinds of relevant interactions
where they might want to learn things about people,
and their mental states, and the words that they're using,
rather than first learning those words through association
and then later coming to this more abstract understanding.
So the idea is that infants might start out
with this understanding of what communication is
and when it's happening, and then can sort of fill
in the rest from there, and that this might be one
of the earlier blocks of that.
So I'll try to go fairly quickly through the rest.
So the second insight I wanted to bring up
that I think is especially important
is that communication requires this focus on intentions.
And this was really the work of Grice
that highlighted this, and in particular, a special type
of communicative intention.
So going back to the example from the beginning.
When someone asks, is there any salt,
Austin proposed that there are these three
levels on which we can think about this communicative
action.
And Grice was the one who really formalized this
by talking about this special kind of intention
that we see in the domain of communication,
human communication in particular, which
is the idea of speaker meaning.
And so his idea is that there's this double-layered intention
that comes when we're communicating with each other.
So we have a communicator who intends the addressee
to respond in a particular way.
So here, the communicator wants the addressee
to provide some salt. The communicator
intends for the addressee to recognize that the communicator
intends to have that response.
So this person not only wants this person to pass the salt,
but wants her to recognize that that
is what he's asking for, that that is the request that he's
making.
And importantly, this third point,
which is that the communicator intends the addressee
to respond that way on the basis of the recognition
of that intention.
And so to make this a little more concrete,
in this case, if he asks her for the salt,
and she passes it because she heard him and understands
that's what he's asking for, that's great.
But the argument is that communication wouldn't really
be happening if, for example, she
was wearing headphones and listening to music,
and she hadn't really been listening to him,
and she just happened to pick up the salt and pass it to him.
So communication, I mean, it would
look like a communicative interaction.
The right kind of outcome is still happening in response
to what he said.
But if she has no access to the actual message,
if she doesn't produce the response by virtue
of understanding what the communicator is trying to say,
then communication hasn't really occurred.
It's just sort of a lucky accident.
So I'll skip this part.
So this is this important kind of intention
that we see in human communication, in which I'll
later briefly mention, we don't really
see in animal communication in the same sort of way.
So how do infants start to get this idea about communication,
that it's not just about identifying
communicative interactions, but also
about understanding these particular kinds of intentions?
So in the '90s, there was this shift
in developmental psychology to looking at word learning,
not only in terms of infants' associations of words
in the environment, but to also, with the work of Dare Baldwin,
to thinking about other people's intentions
when they're using words.
And so she had these really elegant studies where--
with this funny image--
where she pointed out that if infants really
were learning words through association,
then it wouldn't be very efficient for them
because they would make a lot of mistakes.
So for example, in this kind of situation,
here's a dad and his baby.
The baby is looking at this lizard.
The dad is looking at this rooster.
And the dad says, what a cheeky rooster.
So if you as the infant are only learning words
on the basis of associating what you hear with what you see,
you're going to learn that the word rooster refers
to this thing rather than to this thing.
And you're going to get it wrong.
So Baldwin did a whole host of studies
in the second year of life where she set up situations
where infants were looking at particular objects like here.
And then she had their parents or an experimenter look
at a different object and label that one
to see what infants would do.
And what she found is that infants actually
would consult their parent or consult
the other person for cues to reference, to what they're
intending to label.
So if, for example, in this situation,
the infant, when hearing this, instead of just assuming
the word refers to what they're looking at,
would actually look up to dad to see what he's looking at
and then follow his line of gaze to understand
that this is the object that he's actually talking about.
AUDIENCE: At this age?
At this age?
ALIA MARTIN: Yeah, at this age.
Yeah.
So the idea is that infants in the second year of life,
at least, are understanding that understanding what someone's
referring to involves consulting cues to their attention
and intentions rather than just the infant's own.
And I think I'll skip this one.
There are other studies showing this, too.
So in this one, there's an experimenter
who puts these two objects in a box.
The objects switch while she's absent.
And then she looks in one box and says--
the boxes are closed, and she says, there's a sefo in here.
So if the infant understands that they have to pay attention
to what the person knows about or what the person thinks
rather than their own knowledge to figure out
what she's labeling, then now when she says,
can you get the sefo, the infant should actually
pull the object out of here, assuming
that this is the one she's labeling,
because that's the one that she was intending to label.
And in fact, that's what infants do at 17 months.
In the case where the experimenter had a false belief
about the location of the object,
infants tend to go to the non-referred box
more often because they think that that's
the one that she's labeling.
But in the case where she saw the switch happen, so now she
knows what's everywhere, infants will just go to the box
that she's referring to figure out the location of the object
that she's naming.
So this is all in the second year of life, not
those younger core knowledge ages
that Liz was talking about.
So this is evidence that infants consult speaker cues
to intentions, but not of this special kind of intention
that Grice was pointing out.
So I'm just going to tell you about a couple-- well,
one of my favorite studies, I just think that this is really
neat--
where Ellen Markman's lab and then later
replicated by Tomasello's lab, showed
that it seems like children, by 30 months
and then gotten down to 18 months by Grosse et al,
actually do seem to care about not only the effects
of communication, but also that the effects
are produced by virtue of the message being understood.
So you're probably wondering why there's
a dirty sock on the screen.
So in this study, children were presented with two objects.
So they saw, on a table, there were
two objects that were out of their reach, a truck
and a dirty sock.
And the idea was to elicit children to request an object.
Now obviously, the children are going
to request this object, which is what the researchers had
intended in this case.
So children tended to point at this object.
So they had children producing their own communication,
and then the experimenter responded
to the communication of the infant
in one of four different ways.
So she either said, you asked for the truck?
I'm going to give you the truck.
So she expressed understanding of the request,
and she provided the requested object.
In a second case, she said, you asked for the truck?
I'm going to give you the sock.
So here, she expressed understanding,
but refused to commit to the request,
to give the thing the child had asked for.
In a third case, the experimenter said,
you asked for the sock?
I'm going to give you the truck.
So this is kind of a strange pragmatic situation where
the experimenter actually gave the child the object they
wanted, but she expressed a misunderstanding of the child's
request.
And this is the crucial case here.
So the question is, obviously, in the case where
the experimenter provides the thing
and expresses understanding, children should be quite happy.
And in this situation, they probably
shouldn't be very happy.
And what the experimenters measured
was the amount of times that the child
repeated the label of the object that they had asked for.
And they also measured other behaviors as well.
It's this situation that's important for understanding
what kids care about in the context
of this communicative interaction.
So the question is, are infants perfectly happy here
to take the truck and not complain because they
got what they wanted?
Or do they care about the experimenter giving them
what they wanted because their communicated message had
the proper effect on the addressee?
And what they find is that when the correct object is provided,
and the experimenter does not express understanding
of the request, infants actually showed
the most repetitions of the name of the requested object
in this case.
The researchers concluded from this
that infants don't just care about getting what they want
or using communication as a sort of instrumental
means of getting people to act in certain ways,
but rather as an intention to have their messages understood
and delivered to the other person.
So they care about the impact of their communicative signals
on the understanding of the addressee,
not just on the response of the addressee,
which is sort of like the idea that Grice was talking
about with speaker meaning.
Similarly, when children are responding
to other people's requests, they also care about this.
So this is a study that I did in graduate school.
It's sort of the opposite of the previous study, or the inverse.
So we had an experimenter requesting from the child
specific objects for doing specific tasks.
This is 3-year-olds.
So she would request something like a cup
to pour a cup of water.
The child had previous information from playing games
with the objects with another experimenter
that one of the cups was perfectly fine,
and one of the cups was broken and had
a big hole in the bottom.
And so when the experimenter asked for a cup,
the child could either give the cup the experimenter asked for,
which was sometimes the perfectly good cup,
or sometimes the experimenter requested the broken cup.
And the question was, do children pay attention
to the fit between the task and what
the experimenter wanted when they're
responding to her request?
And what we found is that children were much more
likely to give the requested object when
the experimenter had requested a functional object than when
she'd requested a dysfunctional object.
So if I say, I need to pour a cup of water,
can you give me that cup, and the cup is broken,
children tended to go and get a better cup instead of the one
that I had requested.
Interestingly, though, even though children did this,
it didn't seem to be enough for them to give the experimenter
something good that she wanted.
This is a graph of the comments that children
made about the function of the objects
depending on the kind of request that was made.
And what you can see is that when a dysfunctional object was
requested, when children tended to provide
the functional object instead and not respond to the request,
they were much more likely to try
to explain their behavior to the experimenter
and acknowledge what it was the experiment had originally
wanted.
So it seems like children in their own behavior,
by at least three, which is a little older
than the other studies, acknowledge
what the speaker meant to ask for and explain while they're
doing something else, even when they're not
responding to that thing.
And so, just briefly, in the last section,
I'll talk about a third insight about communication
that I think is really important, which
comes from Clark, which is that communication
is this joint action of accumulating common ground.
And so in an example of an adult study about this,
they showed adults pictures like this one of New York City,
and they had people play this game in pairs.
They had people who knew about New York City who were experts
and who lived there, and then they
had other people who didn't know anything about New York City.
And they gave them a bunch of pictures.
They told them that their goal was to--
the person who was the addressee had
to sort the objects in the way that the communicator told them
to.
And so as a communicator, the communicator had to indicate,
because they couldn't see the pictures, which picture
the addressee should put where.
And to do this, the communicator had
to refer to things like the picture with the Empire State
Building in it.
And what they looked at was how people in these interactions
accumulated shared knowledge or common ground over time
and coordinated so their communication could
become more efficient.
And what they found is that when they had two New Yorkers who
were interacting with each other,
they tended to very quickly do the task because they could
recognize immediately, that person's a New Yorker,
and would just say things like, oh, it's
the one with the Empire State Building.
Whereas when they were talking to someone who wasn't a New
Yorker, they had to sort of ground the conversation
by establishing these common reference before getting
to this point.
And so they might start out with saying things like,
oh, move the one with the building with the pointy top.
And then eventually, they would coordinate
on what the actual labels for these things were.
And so Clark's idea is that communication
is really efficient, and we're able to do it
in the way we are because we're thinking
about the common ground we have with other people.
And we're able to figure out what kind of common ground
we have with others fairly quickly.
So if I'm interacting with one of you,
I might assume, OK, we both know a lot about cognitive science
already.
So I can sort of start at a different level
than I might start with, say, a child or someone who didn't
know anything about this area.
And so this is an important piece of human communication.
It seems like-- and Liz talked a little about this,
too-- it seems like infants are starting
to show some signs of understanding
the importance of common ground or shared
knowledge in communication from a really early age.
But importantly, this seems to come in around the same time
that they recognize the importance of speakers
facing each other in conversation
and perhaps putting together some of their core knowledge
domains, which is around nine months to a year.
A lot of work in this domain has been
done by Tomasello, who showed that around nine months,
children were starting to do something different than they'd
been doing earlier.
So under nine months, children tend to--
they play with objects, they interact with people,
but they don't seem to put these two things together.
Whereas at nine months, what they start doing
is paying attention, not just to objects or to people,
but to objects and people at the same time in the context
of a joint interaction.
So they might do things like look at an object
and then look at mom to make sure mom is also looking at it.
Or they might point at things, not just
because they want the things, as a younger child might
do, but only to share attention with a parent
or with someone else to point out
that they're interested in something,
and to make sure that the parent is looking and is
interested in it as well.
So Tomasello argues that this ability
for engaging in joint attention, sharing attention with someone
else, to an object or external referent in the world
is the foundation of linguistic communication
and also cooperation in other very important human
activities.
And it's certainly going to be important for an understanding
of common ground, which is important for communication.
So there's also evidence that around 12 months,
infants start to use prior shared experience
to interpret communication.
I'm going to skip this, I think.
But basically, the idea--
well, I'll just go through it quickly--
the idea is that infants will use the activities and objects
that they've shared with people previously
to figure out what the person means in a new case.
So if the infant interacts with one communicator with one toy
and with another communicator with a different toy
separately, they will figure out the referent
of a communicator's ambiguous request
by thinking about what information
they've shared in the past.
So it seems like they're starting
to track what kinds of knowledge is shared
and what isn't in order to effectively communicate
with others.
OK.
So there's a lot of other important questions
about common ground, but I'm going to skip those now.
I just want to come back to the question of why
infants' understanding and children's understanding
of communication is important for understanding
human intelligence.
So I think that one reason is that when
you think about the insights these philosophers had
and how they seemed to be realized
in fairly young infants early--
children and infants early in development,
when you look at these abilities that humans have
and even that very young humans have, and you compare them
to what nonhuman animals are doing,
things look really different.
And so, just briefly, in animal communication,
we see some of the same kinds of features
that we see in human communication.
So for one thing, animal communication clearly
has a social function in the same way
that human communication does.
So it's socially rich in a number of ways.
I'm not going to over specific species,
but just to gloss over it, most animal communication
is sensitive to the presence of an audience.
So it matters that someone's there
to hear your communication.
For example, species that produce
alarm calls to warn others in their group of predators
will rarely produce these calls if there are no other members
of their species present.
In many cases, the sensitivity to the audience
depends on the identity of the audience.
So for example, in some species such as ground squirrels,
they call much more in the presence of their kin
than when their kin are not around
or when there are other individuals there.
And in some cases, it seems like there might actually even
be a sensitivity to the knowledge
state of the audience.
So this is looking a little more like the kind
of sophisticated communication we see in humans.
So a wild chimpanzee, for example,
will produce an alarm call, will start to alarm call
more if other chimpanzees come over
who hadn't heard the original alarm call
or who hadn't seen the predator.
But if everyone around has already seen it,
they'll reduce their alarm calling.
So it seems like they tailor it to how much information
others around them have had.
However, despite these really interesting ways
in which animal communication is social and complex,
it's also limited in a number of ways
that human communication is not.
So the eliciting stimuli for these communicative signals
tend to be fairly limited, as do the signals themselves.
So there tends to be, say in vervet monkeys,
one cry for a hawk and one cry for a snake,
and they can't realize new signals
for new kinds of predators and situations.
As in humans, the receivers-- or in humans,
the addressees-- acquire information
from the signals of others, but there's no evidence
that this information tells the receivers in animal species
anything about the mental states of the communicator.
And additionally, the communicator's signals
can often cause a response in receivers that's
beneficial to the communicator.
For example, they get a bump to indirect fitness
if they're kin run away and survive predators.
So there can be benefits of communication,
but there's no evidence that the communicator
has any intention of changing the receiver's mental state.
So there's really no evidence of this sort of speaker meaning
or this special kind of communicative intention
we see in humans, which is that a communicator doesn't just
intend for the addressee to respond in a particular way,
but intends for the audience to respond in a particular way
by virtue of having understood the intention
of that communication.
And so this is just a, I think, particularly well-worded quote
from Seyfarth and Cheney who say basically
that listeners can acquire information from signallers,
but the signallers themselves don't, in the human sense,
intend to provide that information.
So the reason, really, for this contrast
between the human and animal cases
that I think if we want to build a model of human communication,
we need to differentiate it from other kinds
of communicative models we could have.
And we also need it to develop the types of abilities
that human infants have, but taking into account
the resources that infants start out with
and the developments that we see in the first few years of life.
So it's not going to be enough to have agents
that can influence each other's responses
or who can understand language, because it
seems like the recognition of these more abstract features
of communication and its causal effects on mental states
is actually present fairly early on as well.
And I think just relating this back to Liz's theory
that infants might have these different systems for agents,
understanding agents and their actions
on objects and then for social beings and their interactions
with each other.
It seems like communication and this type
of communicative intention that we
see combines these two kinds of things, where you have
an intention to produce an effect on someone else,
but by virtue of them understanding the mental states
that you have toward the world and as well as toward them.
And maybe it's the combining of these different domains that
helps infants put together their possibly
human-unique, but maybe not, communication skills.