137: Are Trees Real? (with Yngwie Nielsen and Morten Christiansen)

0:06Daniel, I have to ask you this. It looks like you're, I've noticed in these, it looks like you're outside, but you're not. I take it because it's dark. It should be dark where you are now. It is dark where I'm at. So here's what it really looks like. It looks like a pantry. Check it out. This is where the magic happens. Hello and welcome to Because Language, a show about linguistics, the science of language. I'm Daniel Midgley, and I'm here with Hedvig Kiergaard. Hi, Hedvig.

0:36Hi. This is going to be one of our shorter standalone episodes. We like to do these when we have a topic that we really like to dig into, and sometimes it's because it's a topic that's more current and breaking. Sometimes it's because it's more theoretically challenging, and I feel like this one is both. We found some research that we think is really exciting because of its implications for how we study language and how language works, but we needed some help. And so we have contacted the authors of this work.

1:08We'd like to welcome Yngwie Nielsen of Aarhus University. Hey, Yngwie. Hello. And Dr. Morten Kristiansen of Cornell University. Hi, Morten. Hi. I should mention I'm also at Aarhus University, by the way, part-time. I read the affiliations on your paper, and both of you are in three different places. How does that work? Do you have, like, a quantum state? Yeah, yeah. I do sort of switch back and forth in between. Rather, I'm there a few weeks a year, and then obviously we work remotely as well.

1:38Okay. But now you're being observed, so the waveform has collapsed, and you're both here with us. That's really cool. Okay. Morten, this is your third show with us, which means you're an honorary co-host, and you get to crash any episode you want. Do you want to tell us what kind of linguistics or what kind of language you're really into in your research or just for fun? Well, right now I'm actually working on a book on conversation, so I'm really into how language actually works in

2:08real life, in conversation, how we're actually using it in its sort of original medium, as it were, in face-to-face interaction, sort of almost like what we're doing right now. Of course, we're not actually physically face-to-face, but we're actually visually still, we can see each other and so on. So this is the kind of use of language that I'm really interested in. And it also bears on some of the things that we'll be talking about today, I think. Now, are you into this kind of thing because it gets us out of the abstraction and gets us into,

2:42like, brain stuff, like how we make decisions and how we perceive and is that what does it for you? No, not really in that direction. I'm more interested in understanding language as it originates in conversation. That is, what is it about our ability to use language in the here and now, in talking to each other like we're doing right now in real time? What does it mean for how we should think about the nature of language, the mental representation of language and the cognitive underpinnings of language?

3:13That's kind of what the book is all about. So it's kind of rethinking language from the viewpoint of conversation. That's a very usage-based perspective, a very functional perspective. So, like, what language is doing when we are using it in the... The medium that we're using it in have been using it for the longest amount of time. Text and these abstractions are relatively new things. Yeah, that is... Yeah, exactly. Okay. Yngwie, first-time guest. Welcome to the show. Tell us about your work and what's it about. Thanks.

3:43Well, that's a great question. It's something I'm currently pondering myself being in the middle of the PhD. Certainly, part of it is on the structure of language and this sort of remarkable ability that humans have to put together words in ways that are sometimes creative, sometimes new, but also oftentimes based largely on their own experience with the language. And, like, just taking a basic psychological perspective on that, it's a very remarkable ability. Of course, it's something that we get to practice a lot more than, say, riding a bike or whatever else

4:16kind of skill you have. It's something that you practice from very early on and that you get throughout your entire life. So, certainly, it's not surprising that we're able to do exciting and complex things. And, accordingly, the knowledge that you must obtain is also of a very complex and very interesting nature. And so, that's what I'm sort of trying to probe, I guess, is what is this knowledge exactly? And I think the fact that everyone uses language all the time is both a blessing and a curse when

4:47you're working on languages because it also means that various members of the general public also have a lot of opinions about how they think linguistics and languages work, whereas people don't have as many opinions about, like, how jet engines work because it's not something you do very often. At least, that's what I found. So, it's nice because you can often connect with people because you can say, oh, you know, have you thought about this? Because, basically, everyone has or uses language. But it can be a blessing and a curse. Now, this paper has been published in Nature Human Behavior.

5:22It's called Evidence for the Representation of Non-Hierarchical Structures in Language. Now, if that's going to make anybody in the audience bail, please don't because I think this is important stuff and we're going to make it easy and fun. But first, Morten and Yngwie, is it difficult for you to explain your work to a non-linguistic audience? Have you tried? And what secrets can you impart? Oh, do you want to start, Morten? Well, it is tricky. And this sort of paper, despite its importance, is a bit tricky.

5:52We did try writing a sort of a short, more accessible version of the paper that was also published as a research briefing in Nature Human Behavior. But yes, it is tricky on the one hand. So, explain why do people like trees? For example, what does it mean for what we actually do with language? And so on. But I think we can sort of unpack that, all four of us together here today, if we give it a try. Yeah, exactly. Because that's the first thing you've got to explain to a general audience

6:24is that linguists like to draw trees of words in a sentence, which doesn't come naturally to everyone. I've taught inter-to-linguistics and it takes a while for people to get the idea of hierarchical structure and then to present them with the idea that actually maybe we should critique that view. I think if you pitch it as like a lot of linguists think this and actually it could be this, that part can be intriguing in itself, I think. Okay, so we're starting to talk about trees, but before we

6:55get there, Yngwie, your insights so far into linguistics communication? Right. I think I'm also looking for the secret of how to make my work interesting to the, especially to my parents. I think a lot of people, when they hear that it's grammar adjacent, the connotations that that bears is the first challenge. And then the second challenge is that we all have so much experience with language and I think we take a lot for granted about how it's done and possibly also about like how complicated it

7:25is once you start digging into it a little bit. So I think that's, at least that's the approach that I've been trying to take is unpacking the complexity first and then moving on to why we believe the things we do. Okay. Well, the tree structure idea is certainly one of the more complex things that I've tried to get to my students. So maybe let's talk about that for a second. There are lots of different ways you can tree a sentence, but I guess one of the most common is

7:56you start with a letter S at the top and that means sentence and then it breaks down into two nodes. The first one could be an NP noun phrase and the second one could be a VP verb phrase and then you break it down and break it down and then at the end the leaves are words. But by showing that some groups of words are part of a subtree or maybe a treelit, I'll call them treelits. You can see the little treelits in the tree. I was going to say exactly that I tend to do it the opposite way.

8:31So start with the words in a sentence like this is a beautiful dog and then say, okay, are there any words in the sentence that you think are more closely related to each other than to other words in the sentence and then sort of do a grouping and then say, ah, this grouping is, you can understand it as hierarchical and then we can draw a tree so that brown is closer to dog than it is to this. That's usually the way I go about it. Most linguistics 101 classes introduces you to the basic ideas of

9:04trees and then linguists diversify into like lots of different ways of drawing those trees and movement in those trees and abstract theories. I want to ask why we like trees so much. Why do we love them? I love them. We use them a lot. I mean, who doesn't like trees, right? I mean, we are depending on trees for part of our oxygen, right? So along with other organisms. But I think one of the things that's interesting is that the focus on trees that there is in contemporary linguistics, it's actually a relatively new one.

9:38So the first person as far as I can work out to talk about trees that have like sentence notes, you start with that, you describe a sentence as a tree-like structure to sort of kind of characterize the hierarchical structure of it. That started with Wilhelm Wundz. He put that forward at the beginning of the 20th century as a kind of way of describing the mental structure of language. Now, that was picked up by the structuralist, of course, and then subsequently fell a bit out of favor with

10:10behaviorism, but then it came back very strongly with Chomsky and other afterwards. But prior to that, people didn't really think of sentences or language in terms of these hierarchical structures. There were some earlier sort of very sort of proto-hierarchal structures in the sort of the Middle Ages and the Renaissance, perhaps. But in general, it's actually a relatively new thing. And so I think that's important to keep in mind. And of course, there's other areas where we think of trees too. So for example, oftentimes we think of, say, evolution in terms of trees.

10:43You have these evolutionary trees. But it turns out we know now that maybe that's not actually the best sort of way of thinking about it. And then actually sort of as a little side note, one of the things that's really interesting is that Darwin kind of borrowed the notion of descent from linguistics from August Schleisler. So Schleisler in 1853 was the first person to indicate sort of relationship between languages. So this is not within a language, but between languages or how some languages are more closely related to others

11:16using a tree. And Darwin actually sort of was aware of that going on in linguistics and even referred to that in his notes and in some of his writings. So when he, three years later in 1859 in Origin of Species, he presented the notion of a tree as a way of indicating how species might be related to one another evolutionarily speaking. He was borrowing from linguistics at that time. Of course, now we know that actually that way of thinking about trees and evolution is actually not completely the right way because there's a lot of what's called horizontal gene transmission

11:52going on. So between species that are not related. So of course that happens a lot in bacteria, but it happens even in our ancestry as well. That's why, given that we are all of Northern European descent, we also, all of us have a certain amount of Neanderthal genes in our genome. And that's actually come from crossbreeding across species, which according to these strict trees shouldn't happen. So really what you get instead is these reticulated trees. And it turns out that I think also when it comes to actual language and the sentence, we might be

12:26thinking about the representation as a network rather than as these beautiful trees. So I think the reason why we like trees is it can actually be quite useful in terms of describing the structure and getting people to understand that yes, there are words that go together in certain ways in the way that Hedwig was talking about earlier, that they can be quite useful at a descriptive level. But it's a completely different matter to say that this is actually what's going on in the head as such.

12:57So I think we shouldn't throw the trees away. It's not, no, we're not suggesting that. And they could be quite useful in getting people to understand there are some interesting relationships between words and sentences and so on. But I think it's important that we might want to rethink whether tree-like structures is also what's in the head when we're using language like what we're doing right now. Yeah, I think that's really important to know why you're applying a technique. I have met people who like to draw trees or sentences who say, oh, like, I think this is an

13:31efficient computational way of explaining the structure I'm after. But when asked, oh, do you think humans do this in their heads, say, oh, I have no idea. I make no claims on that. And for me, as a more like functional user space person, I'm kind of like, well, in that case, I don't know if I care that much. Like, in that case, we're just like solving puzzles and maybe teaching computers how to emulate us or something like that. But we're not really explaining what humans are actually doing. As a small side note, at the Institute I work at, Max Planckens for Ocean Anthropology, there's a lot of

14:07research on Neanderthals. And I recently was sampled for my DNA and I'm going to find out how much Neanderthal I am. I'm very excited. Oh, we'll look forward to that. Yeah, I'll tell you my testersel. So if we're not looking at trees, if we're moving away from trees or treelets, I've always thought that, you know, we represent sentences as trees, but we hear the words sequentially, almost like they're beads on a string. They seem to come in chunks. So one thing I've gotten from the paper is we're kind of contrasting trees in which the words are constituents

14:40versus chunks, like pieces of text that are just simply next to each other without any claims on that hierarchical structure, like beads on a string. Am I getting that right from the paper? Well, it's a good question. So it's hard to get out of the tree like thinking, right? You need some kind of other frame of mind. And indeed, chunks is possibly one way, right? It's another way of saying linear or sequential structure, right? or serial structure. So yes, things that are next to each other. Though, I think by just saying next to each other, we might also be capturing some language phenomena that might

15:15not be in the head, right? So it's a little difficult to say exactly where we put this chunk term. Certainly, if you look through a corpus and you look through a text, you can find lots of things that are next to each other that are perhaps not necessarily part of the knowledge we have of a language, though certainly many of them are. Okay. So just to make this super clear, oh, go ahead, Heather. No, I was going to ask if we can maybe take an example sentence. I have a sample. So, for example, here is the red book that my father bought.

15:50So that's a sentence and we could, we hear the words one by one, but we could represent it by a tree. But your paper mentions constituents. Like, for example, in the sentence, here is the red book that my father bought, the red book would be a constituent because that would fit as a tree lit and there's no bits of that three-word phrase that go outside of a tree lit as far as I would draw it. Or my father bought. I think that would be a tree lit as well.

16:20I think that would be a constituent because it's a tree lit depending on how you draw the tree. But book that my, those are three words that I think would cut across different tree lits. So they're not a constituent. They're just three words. So in the experiment, as I understand it, you might want to give people these three words to see if their brains go, I have no idea about the internals of this. Or, yep, I can totally see those three words as a unit even though they're not a tree lit.

16:51Am I kind of getting there? Yeah, so that's certainly half, that's part of it is you can see that people do treat these chunks like units at least to the same level of evidence that we think people treat words like units, which is again an assumption, right? So for instance, if you look at how frequent the phrases, well, that predicts how good you are at processing the phrase over and above how frequent the component words and component phrases are. Moreover, how meaningful it is. Now, it might sound a little strange to talk about how meaningful

17:24things that book that my is, but there is indeed a little variation if you ask people in how meaningful they are. And that too matters in terms of how people process them. So there does seem to be a sense by which, yes, they are treated as units, at least to the same extent that we can claim that words are treated as units. Can I do a test on the sentence? I want to dance. So a lot of tree structure that people would propose would put to dance as one unit and want to

17:58dance as another unit and then I want to dance as the whole unit. I think that's how most like introductory linguistics classes would group those. Two belongs more to dance than to anything else. However, if we look historically, we have actually merged want and two, you could argue, to a wanna. And that arguably crosses between two different constituents, two different tree, did you say tree lets? I'm using the term tree lets. I hope that's okay. Yeah. So that's an example maybe of something that is not only super frequent so that people treat one, two

18:31as one unit, but they're so frequent even that they make it into a word. Is that the kind of things we're looking for? I think that's one of the effects of sort of when you have these sort of frequent occurring sort of chunks or sub-chunks that they can sort of merge together so there's a whole field of linguistics called grammaticalization that's all about how these kind of phenomena can show up. But that's probably a story for a different podcast at some point. Love grammaticalization. But part of that I mean part of the theory is that part of that comes from repeated

19:08use that it becomes compressed both in terms of the duration but also it takes on its own role so it also very interestingly you can use it in certain contexts but not other contexts so for example there's another example like going to that goes into Ghana so say I'm going to go to the store for example but what you can't say I'm going to the store so you can see I'm going to the store but you can't say I'm going to the store but they take on some new roles as well so language is wonderful

19:42in the way it changes all the time and grammaticalization is one of the ways in which you get these changes that come into play and part of that is driven by at least according to the sort of the people who do work on this is sort of on the frequency of these items as they occur and so on and they kind of get shortened and can take on different meanings as well also and Ghana is really tightly fused like when I tell my daughters to stop watching TV will you please stop watching TV they can't

20:16say I'm going they have to say I'm going to I'm going to it turns into something like going to oh that's weird I was going to so Ghana and wanna or actually want to and going to are examples of things that straddle different constituents so they're the kind of candidates that your paper is addressing can you tell us more about the experiments and how people behaved sure so what we talked about before I guess is this is it treated as a unit right is the chunk treated as a unit that's that's only half of the

20:50story because we sort of wanted to say all right we're building on work that says it's treated as a unit but are we also generalizing some sort of structural knowledge across different chunks right so that's so in that case it's not enough to say here we can see it being treated as a unit we need to show some sort of generalization if that makes sense right okay so what we want to know then is do people perceive these chunks that straddle treelets are they able to perceive them as part of a pattern exactly so so

21:24let's give them beads on a string and see if they can recognize them as valid things and if they can then there's no need for us to presume that we process language in tree like units it starts to look like beads on a string are actually real right exactly or to borrow the phrase from before as real as you can show the trees to be so we can't claim to show that there are no trees but we can claim to show that there is more than just trees and then the rest becomes how do you

21:57what do you make of that okay so we're not trying to overturn we're not trying to chop down all the trees we're trying to show that there's a little bit more well we are but we are not there yet so oh we tapped into their secret agenda Daniel but also still trees can be useful for on the descriptive level so but what we want to do is that get rid of the trees in theories of how we process and use language but but you know we're not there yet and you know it's a it's science

22:30we're trying to do science so we can only say as much as our evidence allows us to this is what Ingrid was pointing out exactly okay very humble very good well from reading through the paper these experiments revolve around a lot of priming so can I tell you what I know about priming and then you can tell me how you used this my understanding of priming is that there have been experiments where you get somebody in the lab and you say right we're going to show you three things but don't worry about the first two

23:03things only worry about the third thing we're only focusing on the third thing and when you see the third thing hit a button as soon as you can whether it's a word or not a word right word or not word that's all you got to do for the third thing just hit a button as soon as you can whether that thing is a word or a non-word and then you show them three things so you go not a word not a word word and they go oh that's a word and they hit the word button

23:36but maybe somebody else will get it like this not a word word word and they'll go the third thing was a word but they'll do it slightly faster because that second thing was a word and that sort of paved the way for them to say that third thing was a word yeah yeah so priming is a word that's used by many people in different ways but what you're pinpointing there is exactly the way we think of it you can think of it as sort of very very recent exposure or very very recent experience somehow facilitating

24:09what you are doing in the moment right if you're friends with a linguist you might have experienced that like they want to know how you say a certain word but they don't want to say the word because they don't want to prime you to pronounce it a certain way so instead you might say like oh the fruit that grows on a tree that's mostly red and you put in a pig's mouth and you want them to say apple but you want to know if they say apple or I actually don't know any variations of pronouncing

24:42apple I realized and if you have linguist friends they might do this to you and you feel like it's like a riddle but they're trying to not prime you because they don't want you to repeat what they said exactly so priming is something that also that people have studied in psychology for a long time and part of the motivation for looking at priming is the idea that if you can prime something then we have some sort of representation of whatever it is you're priming in the head so for example one of the things that have

25:16been shown that if you come across a particular word say cat and then there are some other words that come across and then you come across not long after that a cat again what happens is that you're faster at recognizing and processing cat the second time around because the assumption is that you have some sort of mental representation in your head of cat and that is that is the one that is it's still sort of perhaps partly sort of active in your head and so it's easier to access the second time around and that's the

25:53kind of priming that we took advantage of in in our experiment as we can tell you more about yeah yeah please how did you do it and let's let's start with the first study how did you use priming here it wasn't word versus not word exactly so we needed we needed to work with with chunks instead right so we borrowed a task from the chunk literature that's actually very similar to to the word non-word example you gave before where instead of deciding whether a word or a string of letters is real or not it's a

26:30string of words and you have to decide not whether they are real or not but whether they could be used in a sentence so I'll give some I'll give an example for instance a book that my can be used in a sentence right whereas am that the can't be used in a sentence right at least most would judge it would be a very weird sentence it would be a very weird sentence so now we have a paradigm suddenly where people are making decisions on these chunks and importantly it's not just nice chunks right it's also

27:07the the slightly annoying chunks like book that my but that parallels the style of priming that you mentioned before so that's part of it that's one part but the other part which is the important one is you need the generalization right so normally the way that's done is you take two sentences that share a structure that share whatever it is you want the type of generalization that you want to probe and then you try to make sure that they don't share anything else which is a difficult task which is a very difficult task and so

27:44in our case it would be two chunks that sort of in some sense share the same structure but that don't share any words so book that my and husband who who your yeah your exactly his yeah so these examples are great actually because they share the same what's called parts of speech meaning a parts of speech is something like verbs or nouns or pronouns and so on like in this case here and sort of possessive markers depending on how you want to describe it and so these are classes of words rather than individual words and

28:21that's actually what was used in the in the experiment okay so you gave people a really gnarly impossible sequence of three words can't be used in anything that was number one number two they got something like example of an that's a different sort of thing entirely that's that's a different pattern and then third they got wondered if you verb conjunction pronoun and they had to say is that possible and they said yes and the people that got example of an they knew that wondered if you was a possible thing but if they had instead gotten

28:58as part two knew that she now that's a that's a chunk that has the same structure as the target one the number three one and when they got a number two that was the same kind of thing as the number three they were like boom a little bit faster i know that's possible have i got that right that is exactly right the only slight difference is that that in the control condition you wouldn't start with a

29:29nonsense sequence because oh okay you can have so it would always be a real but it would be a very different one they would have a different underlying order of these word classes so it could be like the boy gave their for example okay so in other words some people were like pattern a pattern b pattern c yep i can tell pattern c is possible but then people who got pattern a pattern c pattern c boom

30:00they knew it was possible but faster than the last group and so i guess that tells us that they were able to generalize across patterns even though those those chunks weren't treelets they were something else so that that's the claim right like that you see some sort of generalization here right and the question then becomes what is underlying this generalization what kind of knowledge what kind of regularity have these language users picked up on that allows

30:31them to reuse a little bit of their processing on the second trial when working on the third trial and that's a great like that's a question that we are working on but but what's important here is as you say it's not the tree-let knowledge that comes into play here because these are not tree-lets what were the um the how do you say the red herrings like the sequence of three words that was not a unit at

31:03all that they were exposed to what did they look like yeah so there would be three words randomly put together right and then and and most of the time when you put three random words together it doesn't work out wanted of two wanted of two but of course every now and then it does it does work out so we had myself and some others we went through and checked that there were indeed nonsense but actually if

31:34so for a regular person of course it's quite difficult to think of to think of a sequence of words that that is complete nonsense and cannot be used because that's just a task that you never have you never really have to think of something that's completely nonsensical and unusable but computers are great and did you also have a test condition with what we're calling treelets we did indeed run an experiment where every now and then it

32:06was a treelet and every now and then it wouldn't cohere with the treelet and what we find here is we actually find just very comparable effects so yes they are faster yeah there's not there's not much more to add there of the we weren't expecting the treelets not to work yeah of course okay because they're possible right very possible yeah okay now one possible objection which I know about because I read this and you tested for

32:37it was it only worked because our brains hear the three words and then sort of anticipate a fourth thing and that fourth thing that we're anticipating is part of a treelet so wondered if she liked me if I was like completing it in my head then I actually make a full constituent make a treelet and maybe that's what I'm actually operating on maybe we're imagining treelets yeah well you're being you're you're being real role models for

33:08like intellectual humility by coming up with like critiques of your own work in your own work that's that's very you gotta test everything cool and also emotionally mature is what I'll call it okay so how did you overcome that we tried two things so first we tried to develop a slightly more sophisticated experiment that could work with this but then later we actually also tried to analyze sort of slightly more real life data where we looked

33:38at full sentences and where we could where we could so because we would have the full sentence we would be able to determine exactly what constituent these sequences would appear in or not appear in right but for the experiment we did the following we found four word sequences that were constituents but in which the first three words sort of didn't cohere with the tree-led structure so that would be for instance live in a car now live

34:09in a car forms a nice tree-led structure whereas live in a does not and essentially we just read it the experiment but every single sequence was like this and it was random whether you saw one or the other right so sometimes you would see the full version sort of what we might expect people to represent if they're able to complete and sort of predict how would this full tree-led look like and sometimes they would just see

34:39the little fragment and it turns out curiously that even if you show people the full in this case four-word tree-led it's not better than if you just show them the three-word non-tree-led right now if it was based on sort of trying to figure out how does this fit into a tree-led structure then you would expect them to be slightly better if they were actually given the solution so to say if they were given the full four-word

35:09tree-led yeah that's interesting but they weren't but they weren't but they weren't and how many people did you experiment on and you did run this experiment in English correct well we ran four experiments the first two had 40 participants each all undergraduates and then the second two had 200 participants each sourced from an online platform now is it possible that you accidentally smuggled in tree-lets like the groups of three words that you were presenting to them

35:39secretly were constituents in some way that you didn't realize that is a great question and it turns out that at least in the first experiment we did accidentally sneak in some for instance we snuck in of the best of the best that sounds like a tree-let it sounds like a tree-let exactly because it can occur as he is one of the best it can also occur as a non-tree-let in he is one of the best dancers

36:09so that was actually the big challenge was that we had people work on these three word sequences that appeared out of context but whether or not a sequence of words is a constituent is a tree-let depends strongly on the sentence that it occurs in right so once we became aware of this what we had to do was essentially find sequences that almost never or never occur as tree-lets so we had to really just look through a

36:39very large corpus and determine whether or not these sequences could occur and there are some that never occur as tree-lets that would be for instance sequences ending in the yeah that makes sense unless you're talking about the bad the the two of them oh yeah but that would be an extreme exception i suppose band names do seem to be band names and like book titles like i don't know um i was always weirded out by of mice and men uh because it's it's a part of a longer phrase that i didn't know um and i

37:15was like why is there a book that's called of mice and men that doesn't make any sense and you always hear about like punk bands or something that are just very strange combination of words uh it's very poetic uh but setting those aside i assume you looked at some corpora of some like more more normie sentences yeah yeah okay so it looks like you've dealt with a lot of objections and you found that when people see chunks it makes recognizing chunks easier indicating that chunks are real yeah and and the structure that they that they

37:49embody is a real tool yeah i think that's an important point that that ingry was mentioning here is that they that it's not just chunk of individual words that we sort of were working with in in this paper but it's actually sequences of these word classes rather than individual words and that's important because that adds an important level of abstraction to these generalizations that hasn't been shown before and that we're able to show both for what would conform to tree lets but also what would not conform to these tree lets and that's what we think

38:23is sort of the an important contribution of this paper that we're not suggesting that you only are doing these sort of beats on a string with individual words but actually it seems like those beats would be more like word classes in this case if we're talking about that we had a chat recently with Dan Parker of the Ohio State University on a recent episode and one idea that came up is that we might kind of be doing both or multiple ways of processing sometimes we might do a kind of shallow processing which seems a bit

38:58more like chunks but sometimes we need to do some deep processing which we would handle a bit more like trees or maybe tree lets and what we would like to know is the conditions under which we do each kind of processing so is there space for both kinds of representations can tree lets or trees and chunks coexist here I would say that when it comes to the to the mental representations I don't think that treelets exist in our heads that's that's that's that's my view now I I think you know I think we can you

39:32know if we're doing sort of more deliberate work and so on we can analyze it in terms of these of trees and so on it can be a helpful way as we already talked about to sort of understand sort of the patterns of language and so on but I think when we're using language in the here and now like what we're doing now I don't think that they play much of a role and I think most of the times when people talk about more subtle use of language these are oftentimes very contrived experiments they're not

40:06about using language in the context of a conversation for example because the pressures on conversations are actually incredibly tough on us because you have to respond within just a few hundred milliseconds of when somebody else finishes their terms and so that means you actually have to start preparing what you want to say before the other person has finished what they're saying and that requires a lot of work especially given that we have these severe limitations on our memory and that means that we have to rely on these sort of more chunk based sort of more

40:40shallow ways of doing things and certainly comprehension most of the time you can understand pretty well what somebody else is saying even if you miss one word or two words and so on and even if you don't go into sort of a deep analysis of what they're saying and it's only when we create we as psycholinguists or linguists we create these very complex sentences that have all sort of weird stuff going on in them that people can if they have enough time they might be able to figure it out but most of the time they

41:13actually don't really understand what it is that we are presenting them with and so at least for me and this is my hypothesis and again I want to stress it's a hypothesis that we don't actually use those trees and I think one of the key things I think is important also with this paper is that the idea that we have these kind of tree-like structures in our head that's a hypothesis it's not a fact although sometimes it's actually treated like it is a fact it's assumed beforehand but it is a hypothesis about the mental representation

41:45of language that is how it is that our brains allow us to use language the way that we do it's a hypothesis because we can't really read trees of the brain as such we can't take a scanner or anything like that and find them so we have to try to deduce them from the evidence that we can get from behavior from looking at brain weight patterns and so on but it's a hypothesis and my hypothesis is that actually we don't need it so what I'm trying to do in my work is how far can we

42:16get if we don't assume that now I could be wrong I'm perfectly happy to concede that but so could the people be leaning in the tree list I thought it was really interesting what you said earlier Morten about links between like different kinds of tree metaphors across different disciplines and you talked about historical linguistics and in historical linguistics there's a more and more common emerging view that like if you take a bunch of languages and a bunch of words and you study which ones are common across the languages you can make a tree but you

42:48can also make like a more fussy sort of network if anyone is listening to this show and you google the word densitree d-e-n-s-i tree you can see these kinds of illustrations where you can see lines between the different languages and sometimes all the lines are overlapping meaning that the different analyses of trees are converging on one tree but sometimes it's fuzzy and we usually interpret that as something like horizontal transmission some sort of non-tree like pattern and if we took the words in a sentence and drew lines between them for their relationships it might be

43:20that quite often they end up in these sort of constituent chunks like the brown fox but every now and then you get a link between one and two and i don't know what these links would be maybe something like what would it be co-occurrence or like prediction like how people would predict the next word something like that i don't know exactly what they should be but maybe a lot of the times you can simplify it into a tree structure but we know in historical linguistics that trees are simplifications and there is actually other relationships between

43:51words and other relationships between languages that we maybe are now at a state of the field that we can sort of consider as explanations or worth your study as well okay then in that case let's just pretend that i want to say a thing if i'm not building trees in my head all the time and i don't think i am what am i doing exactly like let's say that i want to ask you for a peanut butter sandwich and in the generative grammar approach i would probably say okay let me choose my verb first want

44:23because that's going to have a lot of the structure in it it's got arguments and they're going to be i and peanut butter sandwich and i assemble them in the right places make a tree and then i say the sentence i want a peanut butter sandwich but if i'm not doing that what am i doing when i put together a sentence is it constructions all the way down uh well i i i am a big fan of constructions so i do think constructions are there but i think there's more than constructions that that's at least

44:55what we're also suggesting with this the current work because i think one of one of the shortcomings of much work in construction grammar is it doesn't really have good good way mechanistically to put the constructions together and i think part of the suggestion is that these sort of non-constituent sequences of these word classes might provide sort of kind of processing glue between them so so what we're doing is that when we're trying to to say something we sort of kind of grab at what what are the most useful chunks that we have available to us

45:26to say what we want to say so rather than for example putting together the red book we might already have an existing chunk so we can use that and that makes it much easier to do and actually i with a few years ago with a former graduate student of mine Stuart McCauley we created a what we call a chunk based learner this was a computational model that actually discovered chunks from being fed child directed speech and then it was able to do language production by using these chunks in order to sequence the output in a

45:57way that would be consistent with what a child would say and so on of course there's much more going on there you have to have some idea of what you want to say you use semantics you also use the context in which you're making that statement to so you might say if you're in a scientific context you might talk about felines rather than cats but if you're just talking with your family you will surely say cat rather than feline because feline would be odd to say referring to your cat for example and so you use

46:28context to figure out what are the right kind of chunks or words you want to use at any given point and of course there is structure to it and that's an important idea also with these sequences of word classes is that there is structure there it just happens to be that it's not a tree-like structure structure and so if we really understand how we use language how language is represented we need to start with how we actually sort of come into language which is through conversing with others it's also presumably how language evolved by some

46:59ancestors of ours trying to communicate in some way face to face using their hands using their whatever sounds they could produce and so on so I think this is some of the big questions and this is why I'm interested in this and this is where this wonderful work with Öngver is adding some really crucial pieces to this puzzle I think that perspective and this happens on our podcast quite often we quite often talk to like you say space linguists and I think I'm on the same page as you are I think the counter argument to

47:31that would be like oh no language evolved because we needed a way of like structure our thought and our mental processes internally to ourselves and that communication is not like it's only or maybe not even its primary function in which case how it works in conversation is sort of like semi uninteresting I've never fully understood that picture and I believe I may be drawing a straw man here and maybe too negatively but some people are interested in that perspective and it generates very different kinds of outlooks and this is why linguistics is so heterogeneous I

48:02think theoretically because there's so many ways of approaching even the basics of the field like what is language for I don't think we want to exclude that language can be useful for structuring your thoughts right I think it can be and certainly I find for example when I'm writing I find that you know it actually helps discover things as I'm writing so clearly the use of language can be helpful in sort of structuring your thoughts and so on but that doesn't mean that it originated for that for me at least it's like yes once we

48:33have language yes you can actually use it in that way as well and and I don't think it's a straw man I mean it's sort of odd that there was a paper that came out just a couple of years ago in nature that that was kind of stating this book by F. Federico and Ted Gibson and a few others if I remember correctly and they're sort of essentially they're stating that language is for communication you would think that's odd I think for most for most ordinary people why would it not be for communication the fact that you have to have a paper in nature stating that you suggest that

49:08it's not a straw man right but I think for many of us especially those of us who are interested in language evolution that is sort of one of the key aspects of why we got language in the first place now again you know obviously we could be wrong but I think most of the evidence falls in favor of that I think currently at least can we go back for a second to the glue I am a big fan of constructions as well and I understand some constructions like peanut butter sandwich that's a construction there you

49:40go you've got it I want I guess that's kind of a construction as well but I never really understood how once we had constructions how do we link them together at which point it just looks like trees all over again but the sense that I'm getting from your discussion of glue is could it be that some constructions have overlapping elements that allow us to hook them together like I guess we've got to dance that's a construction oh want you that's a construction ooh they both have two in them I can drop those next to each

50:12other and overlap those now I'm building something am I getting the right sort of picture yeah I think I think you are and perhaps I can start us off and then you can take over more than a part of what's happening here is I think so the constructions you mentioned here are sort of intuitively we can understand them as meaningful holes in a sense right and I think that's something that actually tree let's does very well it captures what we intuitively think of as meaningful holes right on a side note that might be why they

50:44are so prevalent is because it's easy it's it's understandable and easy to work with these these meaningful holes and that might also be why it's very hard to to think of or or to discover sort of any other kind of structure but yeah so so with your peanut butter sandwich example there are some meaningful holes here to work with like the constructions such as peanut butter sandwich or I want or maybe even I want if we are going back to the wanna case right but then what so so you you do you must put them

51:16together in some sense right and that I think that's been a little that's been a little challenging to specify in the constructionist literature certainly because there are several ways of doing it there's the overlap that you talked about right and but that's not always the case sometimes you can just put things next to each other but but then again what is it that you've known what is it that you've learned that sort of underlies this putting together right and I think this is where modern glue is interesting yeah so these non-constituent sequences they allow you

51:48to combine constructions together so you need kind of you need both so you have this instructions which is a more traditional units that have been studied but then we need ways of combining them together on the fly when we are coming up with what we want to say and that's where these non-constituent sequences could come in providing sort of a glue between the between the constructions but these are you know again it's a hypothesis these are early days yet but I think it it's a exciting hypothesis at least I think so and it fits with

52:19this notion of trying to understand how we can use language as well as we do I mean it's really truly amazing that we can ever really use language given the time pressures and and so on so I think that that is really exciting and I think it's often under under appreciated just how amazing our language abilities is and you know I teach a class on the psychology of language and I try to get people to understand just how much their brains are doing how clever they are when it comes to using language even though what

52:51they might be saying might not be so clever always but nonetheless it's an amazing ability and figuring that out I think we still we still have you know quite some way to go so which is good for for English so he has lots of stuff to do and but I think it's exciting and it's an exciting time to to do this work and I'm I'm I'm I'm very proud of this this work that I have done adding if nothing else sort of get people to discuss these issues so they're not taking trees for granted I

53:22agree I also think it's very exciting and some of our conversations reminds me of a conversation with yeah Dan Parker but also we talked to Steve Levinson again earlier this year and about like how that sort of like fascination and excitement about like how fantastic it is like I make little sounds with my vocal folds and like you get ideas in your head that's kind of bonkers like that's kind of wild right that said and sorry to be the party pooper but like we don't say very new things very often like like I I don't

53:53know how to say this in a nice way and I know we've talked about it before on the show but like people aren't as innovative like if you gave a computer the grammar of English and the vocabulary of English and said make up all the sentences and then you looked at all the sentences people use I don't think it's all of them right people don't say the transparent capybara stole my husband very often we probably doesn't happen very often either but do we need that really I mean you know so why is that being a

54:24party pooper oh because it sort of makes it a little bit less amazing the fact that we can we can we say similar things often which means we can infer things and we can just use the same sentence we used before to say a new thing well it sounds like there are some new sentences flying around here in the last hour I've never said most of those things but I think actually had to be that that that's for me that's a positive thing because that's part of what actually makes it's possible for us to do

54:54what we are doing right so if if I continuously came up with new sentences that you never heard before new ways of putting words together that would just make it really really hard on you so I think the fact that we are doing what you just mentioned the fact that we don't come up with new ways of saying things all the time now we do come up with sort of we take we might take existing chunks and put them together in slightly new ways but probably recognize most of most of those chunks but that that

55:25is actually what I think allows us to be both you know productive and talk about new things that we haven't talked about like you know some of the things we talked about today but also it actually what makes language possible in the first place and I think that's sort of crucial that and you're right that in everyday conversations are you know we use a fairly limited number of different words and limited number of different constructions and so on but that's actually what makes it sort of possible for us to do it as quickly as we

55:56can and I think you know we've been perhaps even sort of waylaid by this notion that there are all these new sentences that we're saying all the time and and and that's what people have been trying to understand whereas really what I'm interested in how it is that we can actually talk about the same things over and over again in real time although it's not exactly the same but we still have to try to understand what it is but I think that's actually part of what makes makes it possible for us to understand each other

56:26so I think it's a it's a it's a good thing I'm an optimist so try it so just to finish up what do you both think needs to change about the way that we study language what should we be doing differently not look at trees no I think that's well not take green trees for granted I like this for granted phrasing right I think it might be limiting our own scientific creativity a little bit right by taking it for granted by assuming well this is this is what it is and then asking questions around that

56:57how do I learn the trees how do I use the trees not necessarily with trees but right and and I think I think there's there's some some some interesting opportunities if you flip it around if you say instead all right well I am learning I am using right okay well based on what I'm exposed to in my experiences what might I learn right might I learn the trees sure but might I learn all these other alternative options right so I like this way of sort of flipping it around a little bit instead of asking well

57:28how might we from what we know of learning and so on get to the trees say well what might we instead arrive at if we say well here's what we know about learning right and that I think that that is just right on with what what he's saying but I think also looking at memory how is it that we can what kind of memory processes I mean chunking is a memory process what kind of other aspects of memory might be important for using language in real time like like we're doing now but I think also

57:59more generally I think one of the nice things about studying language over the last several decades it has become much more interdisciplinary and sort of we are beginning to realize that for example multi-modality is an important aspect of using language where that's kind of being ignored before to to a large degree but also thinking about sort of ecological validity you know how how we how we are using language in in the real world rather than just always sort of focusing exclusively on the lab now labs gives us control and you know as a psychologist I

58:30am very much into control um but on the other hand as a conscious scientist you know I like using computers I like doing things in other ways and so on and I think sort of and I think the field is definitely moving in that direction and I think that that's a good thing so I think I think we are you know we're on a good track I think um but we have far to go but that's good because then we have something to do and it's a lot of fun things to do I think that's

59:02a really nice note to leave it on because sometimes as a junior researcher you can feel that there's some territoriality or that like all like good ideas have already been had and like why should I even this is like a depressive hole you can get into I'm not saying that everyone has this experience um but what you're saying here is like we made this neat study on like this kind of hypotheses on these kinds of informants uh I'm assuming you would like to see this replicated or reproduced on on other data sets on other conditions

59:33other kinds of non-constituent other languages other kinds of people um so there's much more out there to find out that we're only like at the tip of the iceberg which is a nice as a you researcher that's that's nice to hear that there's things left to do that you know Morten and every other senior didn't just like eat all the cake and then like run away into retirement or whatever no no no there's there's much more to be done so you'll have plenty of stuff to do don't worry about that but I think also in

1:00:04in the same vein that too often we forget about the history of studying language right so I think we started today talking about some of the historical precedents and I think it's important to keep that in mind because we you know not that they were necessarily right but we can learn from what was done earlier and I think of too often you know people don't set the what the new findings that they have in a sort of a broader historical context because people have been sort of thinking about language for hundreds if not thousands of

1:00:35years and and yes they're you know they didn't know as much about the brain or how babies learn and so on back then but they they still had some interesting ideas and I oftentimes find it useful sort of looking back and finding something then that to to build on and then sort of taking it forward and and working with it with you know all my collaborators which is sort of great but I think yes you're there's loads of stuff to do so don't worry about it this head which you'll you won't run out of work

1:01:06to do and we won't run out of show topics either the paper is evidence for the representation of non-hierarchical structures in language it's in nature human behavior we're going to slap a link up in the show notes for this episode we've been talking to language researchers and linguistic legends engVe Nielsen and dr morten chris jansen guys thanks so much for coming on the show and talking us through your work yeah thanks for having us we'll do a proper outro on our next episode but for now big thanks to all of our patrons thanks for listening

1:01:37we'll catch you next time because language pew pew pew pew pew pew pew pew pew pew pew