Speaker 1:	Today's speaker is Dan Grodner. Dan has been an assistant professor in the Department of Psychology at Swarthmore since 2007. Before joining our faculty, Dan was a Visiting Professor at the University of Rochester and a post-doctoral fellow at Brown University. At Swarthmore, Dan teaches courses and seminars in psychology of language and psycholinguistics and a research practicum in mind and language. He's also taught the introduction to cognitive science course in that interdisciplinary program.
	Dan received both his bachelor of science and his PhD in brain and cognitive science at MIT. He has received research grants from NSF, the National Institute of Mental Health, and the European Economic and Social Research Council, and he has received several teaching awards as well, all from MIT.
	Dan's scholarship embodies both the spirit and the practice of interdisciplinary study, as you can imagine coming out of an interdisciplinary program himself. His research focuses on a variety of issues within language representation and understanding. Dan examines, for example, how working memory resources interact with how we structure words into phrases and sentences of varying complexity. He also explores how context influences the inferences we make as we engage in conversation.
	Dan has published articles in a range of journals and edited books, many with his colleagues and students. He has supervised students in research and engaged them in his own research projects, and he's presented his work at both academic conferences in other colleges and universities around the world.
	Today, Dan will share his work with us in a talk entitled "Taking Perspective: How Ordinary Language Use Requires Impressive Feats of Mind Reading." Dan?
Dan Grodner:	Thanks for that. The work I'm gonna talk about to day is going to involve a ... or I'm gonna discuss an experiment that was conducted with Maria [Delini 00:02:01] as part of her senior comprehensive project. She's not to be blamed for any inconsistencies or confusion that I may bring to this. Those are my fault.
	So what do I mean by mind reading? I realize it's kind of a cryptic title. What I mean is not something magical, but rather an ordinary kind of sensitivity that we all have to other people's perspectives, intentions and perceptions, and their knowledge state. So let me give you a couple of examples of why this is important in communication. I'm gonna talk about two forms of mind reading that I've been interested in recently. 
	The first is the way we can ... We're very sensitive and are capable of reading into people's intentions by reading between the lines of what they say. For example, here's a very simple, somewhat naturalistic dialogue between agent A and agent B. Agent A says, "I'm leaving you." Agent B says, "Who is he?" Even though there's only six words here, we understand there's a lot going on, right? We infer a great deal of background that must be underlying this particular discussion. Oftentimes, we're familiar with indirect kind of statements. "Nice place you got here. Be a shame if something happened to it." In the right context, that would be a veiled threat. It doesn't have to be, but we can easily imagine a context where that would be true. Even though no threat has explicitly been stated here.
	Here's a famous ... "See my etchings." This is a veiled come-on of course. This, by the way, has been a part of the English speaking culture long enough so that James Thurber in 1932 could produce the following New Yorker cartoon. Here's this hapless fellow, says to this woman in the lobby, "You wait here, and I'll bring the etchings down to you."
	So all of those may seem like somewhat exotic examples. They require innuendo or they involve maybe complicated reasoning processes. But this kind of implicit reading between the lines happens all over the place, even in more mundane examples. So, for example, a statement like "Can you pass the salt?" We understand that to be a request, even though nothing explicitly there is a request. That's an inquiry about someone's ability, right? But only a sullen teenager would respond, "Yes." Right? Most people, if they're being cooperative, they would actually pass the salt, or they would do something. They would understand that you're requesting something of them.
	An even more mundane example: Many [SWAT 00:04:40] faculty are excellent. This could be taken as a compliment if we focus on what's explicitly said, or potentially a negative comment, a derogation, if we understand what's implied. The implication here is that not all of them are excellent, right? So the implication may be false, but the statement is actually true. What's going on here is that even though we do this automatically, something about the use of the word "many" in this context gives rise to the impression that "not all" must be the case. This sort of inference turns out to be universal across languages and across cultures, and it's extremely, extremely common.
	The other kind of mind reading, which is what I'm gonna focus on today, is not just sensitivity to people's intentions as they speak, figuring out their intentions based on reading between the lines, but also a sensitivity to their knowledge, to the knowledge state of the other conversational participants. What do they know, and how is it different from your own knowledge? This is really, really fundamental. I cannot overstress how fundamental this is to communication. In any communicative exchange, there's an asymmetry of knowledge between the communicative participants. If there wasn't, what's the point in communicating? What's the point in talking?
	So it's important to keep track of what you know that's different from what your interlocutor knows. Even the most common word in the English language, the meaning of that word and the use of that word requires keeping track of your own knowledge and the knowledge of the person you're talking to. The word "the" as in "Pick up the cup." What does that mean and how is it different, say, from "Pick up a cup"? Anybody want to take a stab at this? Yeah, yeah. So there's something there that has to do with mutual salience, right? What "the" requires is that whatever's being picked out by "the" is already a salient thing that's shared between the interlocutors. So it's mutually salient. It's not enough, actually, that both interlocutors know that that thing exists and that it's salient to them, but they actually have to know that the other person knows that it exists, and know that the other person knows that they know that they exist, and so forth, in order to use it appropriately.
	So this is what I mean by mind reading. I mean some sensitivity to this kind of knowledge that someone else has. Just to get slightly more technical, there's a distinction that philosophers and linguists have made for a long time between privileged ground ... that's knowledge that is possessed by one person and not the other ... and common ground, knowledge that's possessed by both interlocutors and is mutually accepted as common. This distinction is fundamental to understanding when you want to make a statement. People make indicative statements about their own private knowledge, that is their privileged ground information, and attempt to bring that into the common ground. When they ask questions, you're asking questions about your interlocutor's privileged information, things that they know that you don't know. When you generate commands or generate imperative statements, you are making reference to information that's common to both interlocutors.
	So how is it that we are able to keep track of this kind of information and keep track of this distinction in communication? I'm gonna introduce two broad theories. There are others, but these are somewhat influential in current thinking about this problem. Theory one is that people keep track of the difference between their knowledge and someone else's knowledge, and what's common, by inhibiting their own knowledge. What do I mean by ... and why would you have to inhibit your own knowledge? The reason you'd have to do that is because your knowledge is very salient to you. You know your knowledge. The contents of another person's head are actually kind of mysterious. They're not available to perceptual experience, possibly very open ended. It contains lots of different types of information. So how do keep track of that? It might be really complicated to represent someone else's knowledge and maintain it separately from your own, because your own knowledge is gonna interfere with that because it's so available to you.
	So on this kind of view, what you would predict is that people are actually inherently egocentric. Despite the demands of communication, what we see in communication is that people are faking it. They're really egocentrists, they're egoists, but with sufficient effort and with sufficient maybe inhibitory cognitive ability, they can act as though and maybe even take into account other people's mental states. When I say they can act as though they do it, maybe they fake it. Maybe sometimes they take shortcuts rather than actually fully modeling what's in someone else's head. After all, that's a big model, right? Someone else's head might be open ended and complicated.
	An alternative is that perspective taking might be relatively easy for humans. Humans might be especially capable of this kind of social reasoning. Why might we think that? Humans seem to have a tremendous social aptitude, even in infancy. In fact, it's been suggested that the thing ... that one of the primary cognitive traits that differs between humans and other creatures is our ability to take perspective and our interest in other people's attention, intentions and knowledge. I'm gonna give you a couple of fun examples of the abilities of infants that I think point in this kind of direction.
	One is that humans, alone in the natural world, tend to point indicatively. That is, they tend to point at something to indicate it, to draw someone's attention to it. Even infants do this at a very ... before they're a year old. They might point at something just to say, "Look at that." Other creatures do not point, and to the extent that they do ... Well, an example might be apes that have been trained through intensive training actually can be taught to point. But when they do so, they never do so just to draw someone's attention to something. They do so because they want something. So they might point at an orange saying, "Give me that orange." Whereas an infant would point at an orange saying, "Ooh, look at the cool orange."
	The one possible exception is dogs. There's some research suggesting that dogs are capable of understanding human pointing and that dogs will sometimes point to indicate or to direct the attention of their caretakers. But that's actually the exception that in a sense proves the rule. Dogs have been bred for thousands of years to be sensitive to human knowledge states and may also have this special social competence because of this breeding.
	Another example is when children learn words. When children learn words, they take into account the perspective of the person who's uttering a novel label for a word. So for example, if a child is playing with an object that's new to them and they hear a novel label ... so they're playing with this object and somebody says, "Ooh, pahboo," what they do is they typically look up and try and figure out and register the attentional state, the locus of attention, of the caretaker, of the person who uttered that statement. They ignore their own perspective, what's right in front of them, and they will now apply that novel label to whatever is being focused on by the person who uttered the label, which I've forgotten now. Pahboo? Thank you.
	In this case we see a tremendous sensitivity to other perspectives and an overruling of one's own perspective, even at a very young age. That happens for 18 month olds. There are many other fun examples like this. On this view, this view predicts that people wouldn't be inherently egocentric, but that what might predict our ability to use other people's perspectives is natural social aptitude. Turns out that certain measures of social aptitude are pretty inelastic over our life spans. That is, they're enduring and we seem to a certain extent be born with them. 
	We might be able to look at the autistic tendencies of individuals, in fact, to look at this. Now why autistic tendencies? It turns out that autism, or people with autism, have a special deficit in their social skills. It seems like a special deficit in their ability to take the perspective of others. And there are assays of autistic tendencies that can be used on the general population. It turns out that typically developing individuals vary in the extent to which they display autistic tendencies. So engineers are thought to, and actually measurably do, display more autistic tendencies than humanists. Males display more autistic tendencies than females. In fact, one theory of autism is that it's extreme maleness. And there are other observations like this.
	How do we even study these questions? How do we get at this, how people take perspective and keep someone else's knowledge separate from their own? What we've done is we've adapted a paradigm that's been used by Boaz Keysar and his colleagues at the University of Chicago. What you have people do is they interact across a set of shelves. In this case the shelves have cubbyholes. We've designated one of these people a speaker and one an addressee. The speaker tells the addressee to move objects around. How we create asymmetric knowledge is by hiding some of the objects from the speaker in this case. So initially, what the speaker would see on any given trial is something like this, where all the cubbies are covered. The critical cubbies in this case are the four cubbies in the corners.
	At some point, some of the cubbies are unveiled. In this case, the speaker can now see there's a dog here, there's a cup here and there's a stapler. But there's a fourth cubby which remains hidden from the speaker. The addressee can see that cubby. The speaker is directed to ask the addressee to pick up an object in one of the quadrants. So they have a diagram that says, "Pick up an object in the upper left quadrant." So the speaker in this case would say, "Pick up the cup." Now what does the addressee see? The addressee sees one of two things. The hidden object is either an irrelevant object, it's a fourth object that has no relationship to the target, or it's identical to the target. So we have either a control trial or a competitor trial.
	Note that in this situation, from the addressee's egocentric perspective, "Pick up the cup" is ambiguous, right? There's two cups. However, if they are adopting the speaker's perspective or the common perspective, what's in common ground, they should be able to isolate this cup. Now if somebody in this situation said to you, "Pick up the cup," what would you do? You'd pick up this one, right? It seems really obvious, but it turns out that other groups have found that people sometimes pick this up. I think that's not true, I think that's just a flaw in their experimental method, but there is some previous evidence that people will actually pick up something that's egocentrically salient to them rather than taking into account their mutual perspective.
	So what do we do? One thing I should note is that we're also monitoring the eye movements of the addressee. Now why the eye movements? It turns out that the actual behavior of the addressee is kind of slow to develop and may not be sensitive enough to determine whether people are somewhat egocentric. They may not be sensitive enough to determine whether they sometimes consider this as an option for the target object when they're asked to pick up the cup. However, their eye movements reveal what they're thinking about moment by moment. So eye movements have a lot of nice properties. I'll focus on a couple of these. One is that people tend to not be aware of what they're looking at. Another is that people generate eye movements reflexively; that is, you look at things and you don't even know that you're looking at them, but you do so in response to very predictable inputs in the environment.
	For our purposes, those inputs can sometimes be linguistic. If something is said in the linguistic input, eye movements follow at a very small time window after the linguistic input. They tend to look at objects that are named in the linguistic input. So it turns out that within a couple hundred milliseconds, the eye movements are actually reflecting the language that people are hearing.
	I wanted to show you what kind of data we collect. What does data look like? What I want you to focus on ... You're gonna see a video of this individual's eye movements in a control trial. Here, the target object is the cup, the control object is this jar. The control object again is hidden from the speaker, but the target object is mutually visible. And there's a little doggie here and a stapler. Focus on his eye movements as the speaker says, "Pick up the cup."
	(Video sound: "Pick up the cup.")
	So you see it now slowed down:
	(Video sound: "Pick up the cup.")
	Notice that he looked a little at the doggie, looked back at the target, didn't pay any attention to that control object. I should say that you have to hand code this kind of data, and it can be pretty eerie when you're hand coding slowed down voices in a windowless lab at midnight on a weekend.
	Here's a competitor trial. The only difference here is that the privileged object is identical to the target. So it's another cup.
	(Video sound: "Pick up the cup.")
	So what you can see is that he looks initially at the target, then her looks down to the competitor and looks back at the target. So he directs his attention to something that's in privileged ground, to something that can't possibly be the target of his action in this case. It turns out that's actually pretty common. You see on about 15% of trials, participants look at the privileged competitor, whereas if it's just a privileged control jar, you only get about 5% of trials that people look at that object.
	So it looks like to a certain extent people are distracted by their egocentric perspective. So are people egocentric? Well, on the one hand they never pick up the target, so it's not like people are behaving as if they're egocentric, but their eye movements do sometimes reveal that they're distracted by their own egocentric perspective. So 15% of the time they'll fixate on a privileged object rather than going straight to the target. But notice that's only 15% of the time. That's a small proportion of the time. If they were really not taking the perspective at all, we would expect them to look at the privileged object 100% of the time, or maybe 50% of the time because there's a 50% chance that the speaker is referring to the privileged object as opposed to the target.
	In order to establish whether people are really egocentric or not, and to establish which one of these theories, the inhibitory theory or the social aptitude theory, is correct, what we want to look at is what causes the effect of the competitor, what causes this distraction by the competitor. One idea is to look at individuals' inhibitory abilities and see if they correlate with the extent to which people look at that privileged object.
	Another idea, to examine social aptitude you can measure people's social aptitude. So how do we do this? We measured inhibitory control abilities with a task called the Simon task. I'm gonna try this with you. I think it should work with this room. What I want you to do is to raise your right hand as fast as you can whenever you see a blue swatch on the screen, and raise your left hand as fast as you can whenever you see a red swatch. Okay? So blue right, red left. Here we go. Ready? Go.
	Okay. You probably noticed that there was some interference when the response you were supposed to make happened to a stimulus that was on the opposite side, when the stimulus was in an incongruent position with the response. And that's pretty generally true. What we're seeing here is we're looking at your ability to inhibit that irrelevant response, which is somewhat automatic to respond to things in that side of space. By looking at the degree of interference that any individual has, we can establish their inhibitory control abilities.
	Social aptitude was established by measuring people's autistic tendencies by using something called the autistic quotient ... the autistic spectrum quotient, and in particular the social skills subscale. What we did was we had people fill out a survey in which they basically made judgements whether they agree or disagree with various statements about themselves. Things like "I prefer to do things with others rather than on my own," "I find social situations easy." Agree or disagree. It turns out again that this is reliably correlated with certain traits that we associate with autism. People who are diagnosed as high functioning, people with high functioning autistic spectrum disorders, tend to score very high on this. They tend to score about 70 or 80% "agrees" to these kinds of statements. I mentioned that math and science and engineering types tend to score worse than ... not worse, better ... than humanists. There's also a very high test/retest reliability. So over the course of your life you're likely to have a similar score if you're tested at various points.
	What do we find? It turns out that both cognitive inhibition and social aptitude matter. What we found is there's a negative correlation with inhibitory control, that is greater inhibitory control led to fewer fixations on the competitor, so less what looked like egocentric behavior in the task. And social aptitude had a positive correlation, meaning that a lower social aptitude as measured by higher autistic tendencies led to more fixations on the competitor. This is kinda confusing. What's going on here? We see that there's some evidence that cognitive inhibition matters, that there's some evidence that social aptitude matters, and from the standpoint of the two theories I laid out at the beginning, this seems like a little bit of a contradiction.
	But when you look closer at the data, it turns out that these two measures are not related at all to one another, and in fact they affect very different portions of the experiment. Inhibitory abilities matter only at the beginning of the study, that is, in the first half of the study, whereas social aptitude seems to matter only in the second half of the study. So what's going on here? We're not entirely sure. We're running studies to follow up, but what I believe is that both cognitive inhibition and social factors play a role, but at different phases of perspective taking. When you're in a novel communicative situation, in order to understand how the cues and the context of that situation map on to your perspective taking abilities, that requires some inhibitory ability. That requires picking up the right cues, figuring out which cues are important to you, your perspective as opposed to your partner's perspective. That requires some cognitive inhibition. But once you've established those cues, then your natural social abilities hold sway. That is, what determines whether or not you're gonna be able to take perspective is your social aptitude. So as with many of the great debates in cognition and psychology, it's a little of column A and a little of column B.
	Thank you.