Decoding the Gurus - Decoding Academia 33: The Great Müller-Lyer Debate from Fish Tanks to Eye Operations *Patreon Preview*

Episode Date: June 14, 2025

Welcome to another enlightening episode of Decoding Academia. In this bonus preview of our highly secretive Patreon content, we are discussing a controversial paper by Dorsa Amir and Chaz Firestone that challenges the established notion of the Müller-Lyer illusion being a product of cultural environments. Prepare yourself for some high-level discussions of the visual processes of guppy fish and bearded lizards, as well as the remarkable lengths that psychologists will go to in order to get people to complete their tests. Will our seasoned scholars unravel the illusion, or is this debate another eye-catching mirage? <wink, wink>Sources(forthcoming) Amir, D., & Firestone, C. Is visual perception WEIRD? The Müller-Lyer illusion and the Cultural Byproduct Hypothesis. Psychological Review.Dorsa's summary thread on the paperJoe Henrich's critical thread on the paperChaz's response to the Joe Henrich threadPaul Bloom's Substack articles on Nature vs. Nurture debates and clever experiments

Hello and welcome to Decoding the Guru's Decoding Academia with the psychologist Matthew Brown. And today I'm going to be a psychologist too. I'm a psychologist. I'm a psychologist and I'm Chris Kavner. I can appoint you an honorary psychologist for the purposes of this, because... I am already, I'm an associate professor of psychology. I might be a food professor if you just give me a little while and then you'll have to recognize me.

That's how it works. That's how it works. If someone from another softer discipline hangs around for long enough, eventually we anoint you an honorary. Just give it. I'm not like Sam Harris saying,'m a neuroscientist. I'm actually in a department teaching your undergraduates about your subject. So there we go. My undergraduates. I like the sound of it all over the world.

You are Mr. Psychology. All of the failures are at your feet. Mr. Psychology, all of the failures are at your feet. And all of the wins too, Chris, all of the wins too, which will include the paper we're reviewing today. Yeah. All your wins, all your P on the 0.05. I know how you guys roll. Everyone a win. That's right. Yeah. So before we talk about the paper, I just want to, Yeah. So Matt, before we talk about the people, I just want to, you know, we're having a lot of amount of banter and I have a question. You know, there's like things that you do that you think work, but they might just be superstitions, but they're like technological. Like, so for example, I plugged in this laptop here, I set it up all nice, but Dan was like, oh, I should plug the power in because that will make the recording better.

But I'm like, is that, is that true? Is that work? Does that work? I've encountered your magical approach to technology before Chris, this is great. Well- But I think in this occasion, it must work, right? At least you're not picking the screen

and turning around twice. That's true. No, but it's because when it's on the battery, it's a MacBook, right? So some programs run slower. Like the script outputs slower when I use it. So oh, couldn't it be, man? But I was plugging it in.

I was like, does this do something or is this just like, you like you said, the pigeon packing the screen? Well, look, in the case of these recordings, Chris, we're not limited by processing power, which is the thing that your little Apple Mac is saving by doing that. We're mainly limited by your shitty domestic internet connection.

That's right. God knows how you found one in Japan where they're all amazing. So the only bad internet connection in Tokyo. Yeah. Far. I mean, you're in Bundaberg and you've got a great one. So, you know, that's, that's right. You're fair.

No, I know that's three minutes. That's, that's the end of that. We're not allowed that banter, banter done, mischief managed. So, Matt, I'm going to test you here. Do you know the title of the paper that we're looking at today? I have it if you don't, but I prepared it for you. I'd be glad to read it out. The paper is, Is Visual Perception weird? Capital letters, the Mueller layer illusion and the cultural by-product hypothesis by Dorsa, Anir and Chaz Firestone. Dorsa's at Duke University and Chaz is at Johns Hopkins. Good universities.

Yeah. For coming as well. It's not published yet, right? We're hot. We're ahead of the presses. This is coming out in psychological review, but it's only improvement for him at the minute. Yeah. Well, that's it. We're at the bleeding edge of research, aren't we? So weird, of course, in this title refers to Western... Oh God, I've forgotten what it stands for. Oh my God. My English is better than you. my God. What does E stand for?

Educated. Am I going to have to, what's that word, elucidate or, you know, I need to prompt you. Okay. So Western, educated. What's the I'm at? Oh God. Industrialized. Okay.

I was going to say industrialized, but then I thought. Oh dear. Rich, rich, rich, rich, rich. Very good. D doesn't stand for democratic, does it? It does. It does indeed. Like you might say, Matt, that they chose those words to make the acronym weird

rather than, you know, them being the normal way to refer to those things. But who can say? Yeah, yeah, yeah. Psychologists never do that. Never, never choose words just to make it. Why? So what? That's a collection of words, Western educated, industrialized, rich, democratic. But why does that matter? Well, what is the point there?

Well, the point there is, you know, it's a topic dear to all anthropologists hearts, which is the question of whether or not research in psychology is actually ethnocentric. Is it, is it actually revealing universal truths about human nature, which is what we would like to think, or rather, is it really just reflecting a particular milieu, shall we say? Yeah, so it's a thing that psychologists fret about. With good reason. So yeah, so it's generally a good thing to check for cultural consistency, you know, and not just into cultural things, but like with, with any kind of variability,

you want to check that an effect or a measure works with men and women. If you think it works for all people, for instance, including women in your cycle, even the women, we should even include women, Chris. Um, okay. That is Very progressive. The little ladies are important too. I've often said this. So, now, but the question is, I mean, that doesn't actually mean that it is actually, that we do necessarily see a lot

of variability with every single thing that we study. And there would be certain things, you know, everyone's got a hippocampus Chris, for instance. Most people, yes. Yeah. Yeah. Most people don't want to exclude the hippocampally. Non-hippocampus. But you know, so you know, some maybe biological basic things are maybe less culturally determined, I think, in general

and stuff that is more complex, you know, comes about through learning and environmental influences and so on. You generally expect to be more culturally determined. Now, the topic here is the Muller-Lyer illusion, which is a very classic, well-studied visual illusion. Yeah, among many, right? So there are hundreds, if not thousands of visual illusions. They're really fun. And, among many, right? So there are hundreds, if not thousands of visual illusions. They're really fun. And, you know, I think we understand the biological, you know, neural substrates about some of them, but not others. The Muller-Lyer illusion, Chris, would you want to take us through that? What does it look like?

Well, if people only know one single visual illusion that they've come across in their lives, it's likely this one. The one where there's two lines and there are arrows at the end of the lines and they're either pointing inwards or pointing outwards. And then the question is which line is longer. But as it happens, both lines are the same length, but the one with the arrows pointing inwards appears longer. I knew this illusion long before I knew anything about psychology.

So I think if my description was coherent enough, almost everybody will have come across this illusion, at least in some online or amazing visual illusion thing. So yeah, that's it. Perceiving two lines that are the same length to be different because of kind of contextual visual information, perhaps, right? Perhaps. Just to repeat this, because it's really

central to the paper, right? In case you've been living under a rock and you haven't come across this illusion, just to reiterate, imagine two horizontal lines. Those are the lines you're comparing the top line has got two shorter lines coming into each of the points on each end at 45 degrees, right? And it's the coming in, right? God, it's hard to just

know. You're trying to get a better No, I go ahead. You're trying to get a better. Whose description was better? Whose description was better? Listers should vote. Was Matt's 45-degree angle description better? Look, we'll just post a picture.

Look it up. Look it up, people. All right? You can Google it in five seconds. We're not going to explain it to you. You've all seen that. People will have seen that. Trust me, Matt.

This is not a explain it to you. You've all seen that people will have seen that trust me Matt this is not a rare illusion yeah so there's concern judging from the title of this paper that that this might be an illusion associated with weird populations right western educated industrialized rich democratic societies this might be a visual illusion which only occurs there perhaps because of features in the environment. And that would be the second part of the title, the cultural byproduct hypothesis that this is not a visual illusion that is innate to our visual system, but is one that develops because of features of the environment that you're in. Perhaps features that are more common or only available in developed modern architecture societies, right? Yeah, yeah, in the paper and I presume in the literature that's referred to as carpentry spaces, which is a way to describe them, but the idea is carpentry spaces is not a phrase I've ever come across before. Because I'm raised Christian, whenever I hear carpentry, I imagine Jesus and the cross. Whatever people are talking about, carpentry spaces, in this case, I think they're talking

about angled corners and whatnot, but I'm imagining somebody making a stool. Yeah, with a lathe. In biblical times. making a stool. Yeah, with a lathe. Yeah. Now, but you know what they're referring to is, you know, in artificial environments that humans tend to build, you often end up with a lot of straight lines, or even straight ish lines, and, you know, nice, neat corners. And I you know, there's a bunch of explanations, especially if you live in the

communist society, Mark. Right. Yes. Sure. Yeah. That's what you're referring to. Yeah, yeah. Yeah. Yeah. Brutalism. That's, yeah, I get it. We get it. We get it. Thanks, Chris. Now, what was my train of thought? That's right. So, I mean, there's a bunch of explanations for why this illusion occurs, but the one I think, I think it's probably the most well accepted or it's the most popular is that it reflects the kind of tuning of our visual system to basically the effects of perspective. So when you're looking at a visual scene, a natural visual scene or an artificial one, then you're going to tend to see that optical effect of convergence where lines tend to come together in the distance, right, just due to geometry, basically.

So the idea with the cultural impact of it is that, you know, the fact that you get more straight lines, you get more of these kind of nice neat things, then you're going to be exposed to this. On the other hand, as they point out in the paper, it could well be the case that, well, I think it is now demonstrated, that that is the case, that you tend to see that convergence of perspective even in natural scenes where there might not be such nice, neat, straight lines. So this explanation, I think, is commensurate with both the idea that it's really biological and it's not amenable to environmental change, like it's a hardwired thing,

because you're going to get that effect in natural scenes and also in artificial scenes. On the other hand, it could fit the idea that there could be cultural impacts on it, because if there's more of those scenes in your experience, then there's going to be some learning involved in your visual system for this effect to be heightened. So that's the idea, basically. If you're looking at one of these horizontal straight lines and it's got a couple of converging diagonal lines coming into the ends,

then this is a cue to your visual system that you're looking at something in the distance. So you're kind of, it's further away right, so it's going to appear smaller, but you're kind of compensating for that effect by presuming that it's bigger, that it actually appears right, and the opposite is true for when the angles are coming in the other direction because it's implying that the object is closer towards you and therefore you're sort of, it's making it look smaller. So I think that's a reasonable explanation for the effect.

I know there are other ones, but we probably don't have time to go through them all. Yeah, yeah. So part of the issue around this or the kind of discussion that has come around it is because whenever they looked at some cross-cultural data, if that were the explanation what Matt described, it's a feature of the way that we perceive distances and things converging and what that it should be a universal

feature. Like every culture, every person in the world has the optical blind spot. It's not culturally specific. There just is a blind spot in human visual processing because of the way it works. And in the same way, visual illusions are interesting in this respect because you might anticipate that they are universal, but in this case,

the specific illusion and early claim was that it is culturally variable. And like we talked about, it is related or proposed to be related to carpeted spaces like societies that have more street edges and this kind of thing. And I was aware of this. I've read this in books. I may have referenced it to students, although I haven't actually taught about this in great detail. But it's part of one of the things that people argue when they're saying, look, culture is powerful. It's so powerful, it can actually influence the way that you perceive visual illusions, right? And these illusions, which you see, people in other cultures might not perceive them because of, you know, features

in their environment. So it's part of the evidence that's been offered for showing the power of culture to like influence cognition, right? Yeah, I think it's a great example of a very deep sort of philosophical even issue in psychology, which is it's just a perennial question. It's like whatever psychological property you observe, to what degree is it something that is hardwired? That's a bad term, but I can't think of a better one off the top of my head, you know, biologically determined versus something that has learned a sort of blank slate sort of approach. And, you know, it's definitely like a bit of both.

On one hand, human brains are incredibly knowledgeable, incredibly flexible in the way in which we can approach things and find solutions to problems and find ways to satisfy our various desires. On the other hand, it's also incontrovertible to say that, you know, our brains are not an undifferentiated mass of neural goo that just refits itself to anything, right? It is incredibly modular. There are a lot of specialized processes as well that don't really change fundamentally in ontogenesis

and throughout the lifespan. So it's a complicated question. The answer is going to be different depending on the topic that you're looking at. So the question here is, does it apply in the case of this real classic fundamental visual illusion? Yeah. Yeah. And there are plenty of things which are culturally variable.

I'm interested in cross-cultural psychology and I agree like, uh, just off the top of my head, the way in which self-promotion is received in different cultures is different. We, me and Matt talk about this all the time on the podcast because there's an allergy to self-promotion in, you know, Northern Irish culture, Japanese culture, very strongly Australian culture, but not so much in American culture. There is in certain aspects, right? But this is just, so the thing that can be adaptive socially can vary. But even with that, I'd say it's nuanced, right?

Like, while the ways in which people can express or pursue self-promotion and achieve social cachet would vary hugely between cultures. I'd say almost every culture, people generally would like to increase their social status. Yes, yeah. Yeah. So that's that's a good example that like there's nuance to him because like maybe the way to self promote is to self denigrate in a given society. Like, you know, there's just it is an interesting thing.

But I don't think you or I have any issue with the concept that like culture is extremely powerful. Now, I imagine this because this paper is saying, OK, this illusion has been in previous research touted as a powerful example of the power of culture to shape cognition and visual perception. And just reading from the abstract here, exception and just reading from the abstract here, the cultural byproduct hypothesis bears on foundational issues in the science, philosophy and sociology

of psychology and remains popular today. Yet here we argue that it is almost certainly false. OK, they're coming out of the gate shooting, you know, this is an often cited result that it's variable. And basically the previous finding or the claim is that in societies where there is less carpentry or less modern environments, right, then the illusion is less effective and people don't see it as much because there's not as much street edges in their environment, but they're going to argue that is wrong.

And they're going to supply five separate lines of evidence for that. Yes. Um, yes. So let's work through them. Shall we? Um, yeah, we won't read the diagram. They did. So let's start with number one. Um, this is probably the best.

You shouldn't lead with the best. You should, you should, you should put number. Yeah. But they, they, they like some of the other ones. I mean, they're all good. They're all good. You could take one of these. Yeah.

All right. Number one, the, it is pretty strong. It's pretty strong. The illusion is not limited to humans appearing in non-humans from diverse ecologies. Right. So let's, I've got to scroll down now to find the section where they deal with that. Guppy fish, Matt. It's guppy fish. I mean, there's other ones as well, but they essentially trained guppies that if they approach like a line that is longer, they'll get more rewards.

Right. So you train the fish, you go towards the stimulus and you get a reward. Right. Then you put into its fish tank, the lines, right. With the different arrows. And it goes towards the one which suggests it is making, you know, the mistake, the error, beautiful. It's such a nice experiment. It's beautiful. It's such a nice experiment. And it's a very big blow to the carpenters.

It is a significant blow. And it's been shown in other fish species, as well as guppies, parakeets, pigeons, horses, capuchins, bearded dragons, species of lizard. I think I think they're Australian, right? Yeah. And even they claim emerging the foraging patterns of ants. I find that surprising. But I didn't check that particular citation. I know that I but I was in a lab that was doing studies, comparative studies on ants and humans foraging behavior.

So I was sometimes amazed that the, you know, the ants foraging collective patterns is often very intelligent, even though the individual ants, not so much. But I am curious about how you could demonstrate that for foraging patterns, but I didn't read the paper. Anyway, so it's also, it's been shown that like, because these are like repeated measures experiments where they get the same guppy, you know, again, again, again. So they can even test if the effect is statistically significant in each individual fish, or each individual animal, as well as the group. And you know, for the large majority of them, it is in fact, except every parakeet, every

pigeon, every capuchin, and all but one bearded dragon, guppy. What was that for, dragon? No, it's not. There's something wrong with that particular bearded dragon. Well, I also noticed it mentioned that it can also be detected in the geese pattern of flies. Right now, one point to note here

is that these things all have different eyes, human eyes, and fly eyes, quite different, right? Quite different in the structure and visual processing. But this would imply it is a very fundamental illusion. And the reason why I'm sympathetic to that imply it is a very fundamental illusion. And the reason why I'm sympathetic to that is that I know from other topics in visual cognition and in particular, I'm thinking of study, like computational studies where they do things like, like show, uh, like a neural network model or a statistical model, a whole bunch of images from natural scenes, right.

And they sort of let them learn their own retinal coverage and things like that. network model or a statistical model, a whole bunch of images from natural scenes, right? And they sort of let them learn their own retinal coverage and things like that. And you tend to see response patterns that fit things like the complex cells in the primary visual field and stuff. So there are other lines of research which show that there are like statistical regularities in natural scenes, which are governed not just by the kind of stuff you see, the physical stuff you see in a natural environment, but also by the geometry and optics and so on,

that would apply to all animals with any kind of eye. So that's interesting. So that is a strong finding. That's a good start. it's a good start. There are some counters to that. Like, Oh, what about the fish? What if they were, you know, they've been raised in an aquarium. Maybe they were seeing the corners, but they point out, well, hang on.

They've only seen like, you know, imagine a fish in an aquarium. They're going to see some corners at the, at the edges of their tank, but they're never going to see, so they're going to see angles going in, like converging ones, but they're never going to see the opposite one, right? So, you know, it kind of, the countless of this don't work. I think it is basically just a very strong argument in favor of this position. Okay. So they're starting off, well, neither second, second line of evidence. And I like this one as well, though it took me a little bit to get my head around it. And didn't I didn't like me like Chris didn't like me. Doesn't surprise me.

But that means I should explain it so that the listeners could understand. So they you know, part of this argument is that there's a significant difference in the layouts of natural and artificial environments and like obviously there is in the fact that, you know, a cityscape looks different than a jungle. But the question is, in the crucial components of the Moller-Lyer illusion, are those aspects less common in natural images? And a bunch of researchers did a rather, I guess, like processing heavy,

not the kind of thing that you could do without a computer, right, where they analyze the pixels in natural images, a large repository of natural images. And well, the kind of spatial distribution of the meant that you wouldn't come across this illusion in natural images. And they, they find no, first of all, that they are present in natural environments, just from the layouts of scenes. And then they, they did the thing which you should do, which tested, ah, but when you take a bunch of artificial city environments, you know, kind of highly carpeted spaces, as you might put it, is there more representation of the kind of angles and distribution of shapes that you would want to detect the Mueller-Lauer illusion than they say?

No. So it doesn't seem that there is additional stimulus in a highly carpeted environments that would actually help, right? This is what they're saying. Is that right, Matt? Now you can correct me anything I got wrong there. Yeah, that's basically right.

I mean, the basic premise is that, yes, the illusion, the classic version of the illusion involves straight lines, but this other research has pointed out that the underlying pattern where converging lines, wiggly or not, tend to mark out, you know, an object which is further away and therefore smaller than it appears, and also the opposite, holds true. So, and you know, again, this makes sense to me, right? Because it's like a geometric optical property.

So it's gonna be something that you're gonna see even in natural scenes with grasses, trees, and gentle slopes. And I think this point becomes stronger when you move briskly onto the third one, hey, Chris, because they're kind of why don't you tell us about it? Yes, this one is pretty good. Right. So the other way I remember, remember the argument for it being culturally determined is that those of us growing up in brutalist Eastern European architectural regimes, surrounded by... It's very modest, right? People growing up in East Germany, yeah.

Yeah, surrounded by this modernistic hellscape, full of all of these straight lines and angles. That's why we're seeing this illusion. But 4.3, the third argument is saying the illusion is not limited to straight lines or arrowheads. In other words, there are other versions, many, an infinite number of versions of, in fact, of the Muller-Lyer illusion that work experimentally, not just the one involving straight lines. And I've got a great diagram here, figure five, which shows, compares it with one involving curved lines.

And you can look at it, right? And it's working on me. You can see it involving where there's even no lines at all, just a couple of points surrounded by curly lines. One D where there's no, not even any curly lines, right? They're just, they're just different colored points arranged in these, in these patterns. And then the real kicker is

number E, where you've just got four points. So, you know, two sets of red dots, I presume they're equally spaced from each other. And on one of them, they've got like a human's face sort of pointed on the inside of each dot. So they've got like a little red nose. And on the other version, they've got human faces on the outside of those dots. So there's just empty space in between the dots and the visual illusion is just as strong. So this seems to be a very clear demonstration

that actually the illusion does not depend on straight lines at all or angles. And therefore it seems to completely eliminate the rationale for there being a weird cultural bias there. Yes, yes. And like you said, the diagrams are quite neatly presented in this. It's like the people have a red nose in the last image. You really should look out the paper because it's good in that respect. Then I don't know, Matt, this is,

I feel like MHC is a little bit of a Rorschach towards like, well, tell me what you see in that image. Maybe, maybe that's just me. see in that image? Maybe that's just me. In any case, with the three lines of evidence that we have already, you've got like a pretty strong case. Okay. I think this is a pretty good case. The fourth piece of evidence though is also good. All five of them are good, but this one is that people who are blind can also observe or it's not observed, but also experience this illusion through touching. Yeah, exactly. Experience it through touch.

So actually that's interesting, Matt, because it's also then not just an optical illusion. It's a geometric illusion, which you kind of talked about. Yeah, and to be honest, I think actually the fun thing about this paper is that I learned a lot more about the illusion than I knew before, which after it wasn't a great deal. But yeah, I did not not know this and I'm super surprised. So basically they created like a braille version of the illusion, you know, the

lines and the angles. So people feeling it with their fingers are getting the same effect, which actually completely, you know, I think probably undermines not only the idea that it's culturally determined to some degree, but actually undermines that sort of standard explanation that I outlined at the beginning, that it's got to do with the optical properties of visual scenes, right, Chris? Or perhaps is it the case that people who, like we know that people who are blind from birth do sort of recapitalize and like a lot of interesting things happen in terms of

them developing like an intuitive sense of vision, but doesn't depend on vision. If you don't, I mean, and maybe something like that is happening. I don't know. It's a bit beyond my Ken. Yeah. Yeah. It's a, it's an interesting result. Yeah, yeah, it's a it's an interesting result.

And in any case, unlike again, it's just one of the four lines of evidence that they're offered, which is very impressive. Five, five lines. Oh, yeah, I mean, sorry. Yes, I misspoke. I meant one of the four lines that we've looked at so far. The fifth the fifth one that is the last one to mention is, you know, the other ones, they're all good, Matt. They're all pretty impressive. This one I ever feel like it's sort of the icing on the cake.

I think it's like that Simpsons clip where they're kicking Krusty off. Stop, stop, he's already dead. Yeah, the zombie is dying and you've already double tapped them, but you're going to just pop a couple more rounds to be sure. So the fifth line of evidence, which is quite amazing, is that the cultural byproduct hypothesis relies on that this is an aspect that you learn from interacting with the environment, in particularly through the visual field. We've already seen some issues about that interpretation, but setting them all aside, this would mean that if you had an individual who was not able to experience visual stimulus in, you know, any significant capacity.

And then suddenly were granted that ability and you immediately tested them on the Mueller Lahr illusion. They shouldn't experience it, right? Because they haven't had the visual. Now, if you might think that psychologists would not go to such extreme lengths in order to test their theories, but you would be wrong because Gandhi at all in 2015 recruited nine blind children with dense bilateral congenital cataracts. They had lens replacement surgery.

They wore an eye patch for 48 hours. Then they took off their eye patches straight away. But before they even got a chance to wonder at the wonderful world. The psychologists were there. The psychologists were there with their motor-lighter illusion to test them. And guess what?

Guess what? Can you guess, Chris? Yes, they all observed it. Amazingly, it was nine participants, right? Because obviously, this is a very rare situation where you have people that are having sight restored after being blind for their... And then getting a psychology test. Like you said, it's a rare situation, but they did it and they were all able to observe and they did multiple tests of the individuals.

So it's a well conducted test. And the fact that there are nine participants is perfectly understandable given the circumstance and it actually isn't an unreasonable sample because of the methodology they employed to increase their power. Yeah, yeah, yeah, yeah. It's perfectly fine in this context, of course, to have a very low sample size. When you have an effect size, apart from anything else, this incredibly strong, they've got a, they've got, I think, tongue in cheek little figure there, figure seven beakers where they've got a graph.

Now this graph breaks all of the rules of the visual presentation of data because most people would say, oh, this is overkill, you don't need to do the graph. But it's basically on the Y axis there is percentage of illusion consistent choices. And then there's two bars, one for controls and one for nearly sighted.

And both bars are from exactly equal length and they both go up to a hundred. They're both exactly the same. Um, well, a little bit. I liked it. I was using before that as well is like showing a cataract surgery, right? Like it's showing a kind of side slice of an eye and what happens when it's removed, and then showing the Müller-Lyer illusion under it. So I really like these illustrations. It's a very clear demonstration of what Gandhi et al did and what they find. Yeah, rhetorically very effective, I think, in a good way. So look, obviously the paper goes into a lot more detail than we've given here, you know,

where we've just scratched the surface. Overall, the tone of the whole thing, Chris, is very, very careful. Are these guys actually philosophers? Because it has that sort of... It does have that kind of ring, but I think, Matt, you can claim them. They're in the Department of psychology and brain sciences. I read that at the beginning. That's right.

And I forgot. No, they are psychologists. Well, good job. See, psychologists, we didn't need philosophers, Chris. We can do it ourselves. Um, psychology is going, going their own way. That's I approve. I was also going to mention that they outline these five lines of evidence, which cause some

issue for the predominant interpretation of the Müller-Lyer illusion and its cultural variability. But there is an issue that there is a body of evidence that suggests it is culturally variable to a significant degree and that that aligns with the degree to which the societies that are being sampled from, you know, have modern environments and this kind of modern architecture and carpentry spaces like we've talked about. So they then go to basically do a critical review of the, critical review of the not all of the literature, but kind of the most commonly cited studies and historically the most the studies that were the kind of set off this topic. And they make a strong case that there's significant issues there. And they're not claiming that it means all of that is false, but just that given

discrepancies in it, like they're pointing out, for example, how do you quantify the degree of carpentry in an environment? And they go back to the original descriptions given and point out that in lots of these environments, there are descriptions of rectangular structures. So their argument is actually the secondary literature is more guilty of like reifying this distinction between, you know, like a binary, natural, non-carpentry environment versus the modern environment. But essentially they look critically at the studies and they argue that for various reasons, which revolve around like data collection, translation issues, researcher degrees of freedom, like people excluding participants that, you know, give features that are in the environment. There's

just a lot of reason to be skeptical of the previous literature. When you combine that with what they're talking about, the five lines of evidence they present, it means that we really, at best, should be highly ambivalent about the state of evidence at the minute for this illusion being culturally variable. Yeah, that's right. You know, the kind of cross-cultural research that was done, like you said, is vulnerable. It's just a bit messy. There's some messy constructs involved having to differentiate between these environments and some subjectivity there. And there's also some research degrees of freedom involved

in terms of rejecting, in scare quotes, bad data and so on. The usual stuff that we've kind of observed with the replication crisis type stuff. And so, yeah, I think it's kind of a matter of comparing the weight of evidence on both sides. Like we went through those five things, which is incredibly strong, whereas the evidence on the other side of the ledger is much, much, much weaker. So yeah, I think we have to agree 100% with their conclusion there, which is that I think they described it as the cultural byproduct hypothesis, which

is how they describe the kind of like just being a little bit neutral about the actual causal mechanism there, but just saying it's got something to do with these modern environments is almost certainly false. And I would have to agree. So yeah, what do you think, Chris? Did you enjoy this paper?

It's great. This is like, you described it, Matt, that this is kind of catnip for me because it's a paper, which is, you know, it is providing like a critical evaluation of existing literature in a very convincing and well-argued way. And it actually also makes reference to, as you said, things that we've learned about from the replication crisis, about researchers degrees of freedom. Not to say we should dismiss all this

previous research, but just that now that we're looking critically at it, and there are these issues, that we could now construct much better tests of this. And that's what they suggest at the end. They're saying, we don't think, their cards are on the table, they don't think that this is a culturally variable phenomenon for all the reasons that they stated. But you could pre-register design, you could do an adversarial collaboration with people who are arguing other days. You could have very tightly controlled methods, include different kinds of stimulus like they presented, the sideways face and the curvilinear examples and stuff. You could do a really neat test of it.

This to me is a really good contribution, especially because it's taking a target at a thing which is cited so much, which is such a, you know, appealing example for all sorts of reasons. It's an easy thing to teach the undergraduates. It's kind of good to illustrate, you know, that culture is an important variable to take into consideration. But all of that can be true. And this illusion may well turn out to be not so culturally dependent. Right. Yeah. Yeah, that's right. Yeah, like there's, it's probably a bunch of, well, not probably, we know that there are a bunch of, I guess, zombie ideas, findings in

psychology that kind of persist because they get included in undergraduate textbooks and they get taught. And people like me don't really think about them much. We just read it in the textbook and we repeat it, you know, if it's not in our special area of focus. And therefore it sort of persists. And so this kind of work is really valuable. What I appreciated about it is it's just it's so well argued like it's basically drawing together and it's not it's not a philosophical argument although they do do some very careful reasoning there. It is referring to and drawing together a whole bunch of empirical evidence but it's just set out and argued in such a clear and compelling way. It was

just enjoyable to read, which is rare. I learned a bit more about that. I'm more mystified by this illusion than I was before, right? Before, at least I had a tentative explanation for what's going on, but the stuff where even people are like, it's tactile, people that are congenitally blind. Yeah. So that means we, you know, further research to require to just like putting aside the whole cultural variability thing. What's going on with the solution? This might speak to something that I find interesting and sort of variable in academia. I think I've maybe mentioned this, but I've certainly talked about, you know, culture being able to influence things. And I'm aware that like some of the results about analytical versus holistic thinking,

or like these things which are often used to show, you know, Japanese visual perception is different than North American visual perception, they haven't fared so well in replication. So I was already like kind of interested in this topic. But in my case, and this might be because I'm like not invested theoretically, like to that extent. When I read a paper like this, I'm like, oh, wow, this is interesting. You know, I had this understanding from the literature, but this makes a very strong case that my understanding is wrong.

And I'm actually like kind of excited might be overstating it. But this is the kind of thing I would want to teach undergraduates about. Right. And like maybe put them papers advocating for, you know, the kind of classic studies showing the cross-cultural variation, then this paper and not saying, OK, now you have to completely dismiss or take sides, but more like this is a good example of like a very critical paper, which ignites a discussion and may very well overturn like a longstanding part of a theory that is out there. And so that to me is like exciting, but I do see that in some respects people respond with like anger

that this kind of paper exists, you know, they don't like it and they consider it kind of, you know, impolite or I don't know, I don't know, like just kind of that it's be smirching a whole bunch of researchers because a lot of people have talked about this effect. Yeah. Well, I don't approve of that kind of thing. I think I think your instinctive reaction to something like this should be curiosity and just interest about finding out. You know, it shouldn't be an unpleasurable experience to find out that

something that you thought was true probably isn't, right? That's a jumping off point for learning more stuff about the world, having a better understanding of what's going on. And I, like you, I, like you said, you know, we're not, we're not theoretically invested in this. So maybe that's why we're, we's why we're pretty savoir faire about it. But that is the correct attitude. And it is a jumping off point for more interesting things

rather than just repeating the stuff that we think we already knew. I mean, they mentioned that in the discussion areas a bit more. And they point to the broader issues about the degree to which certain visual illusions or certain kind of holistic or gestalt kind of processing can be affected by culture versus not and you know they mentioned some interesting ones with these illusory letters phenomenon right

so if you're doing an eye test and you know you're trying to perceive some some hazy letters in the distance right you can't quite make them out you're doing an eye test and you're trying to perceive some hazy letters in the distance, you can't quite make them out, you're probably more likely to fantasize a letter that you're familiar with. So if you're an English speaker, you probably imagine a letter from your alphabet. But interesting, they mentioned some evidence here that, you know, it doesn't seem to be true at the word level. So if you take a sentence like she w dot dot t to the doctor for a w dot dot t on her foot, then you might expect, oh, you might fantasize, like she went to the

doctor for a wart on her foot, right? Because that makes sense at the sentence level. But surprisingly, those effects don't seem to occur. So yeah, it is, I mean, the more general question is to what degree does learning and experience have these sort of top-down effects on perception is a really open question. And if it is occurring, like at what level is it occurring and how? And, yeah, it's a very complex topic and, yeah, just very interesting. Now, a sociology of psychology comment on this, Matt, because, you know, we are not invested in this topic very strongly or theoretically, right?

I find very few things that I am. So, you know, we are not invested in this topic very strongly or theoretically, right? I find very few things that I am. So, if I'm strongly invested, it could be because I've published multiple papers. But nonetheless, Joe Henrik, on the other hand, is quite strongly invested. And he is one of the main people that is cited throughout the paper as the kind of like, here is an example of someone making this claim, here is evidence why we think this is categorically wrong. So as you would expect, he didn't welcome the way this paper was presented. Now to his credit, he did say, for example, I've just written here, thanks again for your paper,

Doris O'Riomir and Charles Firestone disagreement. There's a lifeblood of science. I'm replying to this paper into storm tweets. See below. Okay. So that's a good, that's what you want, right? Like this is a robust criticism. All right, let me get my hands dirty.

But in his response, I have to say that there are various, But in his response, I have to say that there are various, like what I would consider fairly snippy retorts. There's a point, and this made me actually remind me of like, you know, the people who recovered the gurus because they said the author set up what they call the cultural byproduct hypothesis, which they do mostly by citing papers I co-wrote 15 to 20 years ago, published in 2010 and 2006. Interestingly, they missed the oldest of these, which was published in 2008, but written first. A big oversight. Okay. So is that a big oversight? Because in the response, Chas Firestone wrote a response to this, and he pointed out that actually they didn't invent the term.

They're quoting it directly from the paper. So it was called by Joe Henrik, the cultural byproduct hypothesis. But they also mentioned that looking at the 2008 paper, which they didn't cite, you find the same kind of statements. So it's not a huge oversight as it's presented. And then Joe also suggests that they're setting up a straw man hypothesis, which is based on a like binary, they see it or they don't see it, a nature versus nurture, like kind of take, which is just like a false dichotomy as he presents it. Well, I did not get that sense from the paper at all.

That's not really relevant. Like a lot of the experiments are a false choice, right? The guppy can only swim towards like one line or the other line, right? But to say that that's flattening things into a nature nurture thing is really no. There's also, he mentions, you know, they deliver this view by avoiding it rhetorically with their straw man and luring the reader

into categorical thinking. Either you see the Mueller-Lyer illusion or you don't. They don't look at developmental data brackets, which is odd. Right now, they do look at the data because the fifth line of evidence was talking about people with congenital, is it congenital? What's the yes. Yes. Yes. Like in essence, that's developmental a

developmental research people right because it's But it's yeah people. Yeah with and without the developmental experience. Yeah Well, that is that does sound unfair to me Chris and the other thing that's interesting about that thread I've only just looking at it now is that Joe Hendrick is sort of citing a whole bunch of other visual illusions and Yes, yeah, you know, what about these ones, you know, you can see them because you're you're weird but people in other cultures Can't see them and you know, I don't know anything about that research But my point is is that their paper did not make claims about other visual illusions. It was not like a broad scale thing.

It was it was about this specific thing. So it's just a bit odd. It's a bit of what about ism, right? It's like, yeah. And we discussed the end of this thread, which says there's lots of great stuff in Dorsey and Chaz's paper, but also some serious issues in the future, I would encourage them and others to share their work with those that they disagree with prior to publication. Surely this paper could have been improved if they had gotten this feedback. For example, they might have learned that Herrero and Audji

Herrero are not different dialects. It's just how you say Herrero in Herrero, like saying folks in Munich speak German and Dutch. Run your paper past those you criticised before running off to the press. Well, that's an incredibly important thing that they needed to. That does undermine the power points. Look, I've got to say, you know, this is understandable because, you know, your work has been criticized, you get a bit testy and you add in some like, you know, shots. It's understandable.

But I do think like, you know, we talked about this issue about like, you know, first, you must contact people privately before you issue any criticism. Like, no, that's not necessary. And it parallels what we see in the ITW gurusphere too, privately before you issue any criticism. Like, no, that's not necessary. And it parallels what we see in the ITW gurusphere too, which is, you know, how dare you criticize me publicly? You should have come to me in private. We could have sorted this out behind closed doors. How indiscreet, how impolite. I don't agree, right? You put the paper out, you do your best with it.

It's a very strong paper, I think, and it's a very worthwhile one. Maybe it does have some little deficiencies. Maybe it could have cited this extra paper. Yeah, all papers move. Yeah, all papers have deficiencies, but you do not need to consult with person A or person B about anything before you publish.

And if there is anything serious, maybe you and I are not qualified to judge, you know, Gats on the argument. Maybe we're not aware of some excellent counter arguments that Joe Hendrick is aware of, in which case, right, your own baby, right? That's what the literature is for, for researchers to communicate with each other publicly.

Yeah. And you know, Charles Firestone did do a thread, by the way, you would be interested in map. He makes the point that they weren't making a broader argument about, you know, all visual illusions not being culturally influenced. But he does, however, question and point of research that has given alternative potential expeditions for those illusions cited. Well, I have to say, yeah, people can, we'll link to the thread of this thing because Joe Henry, in one of those tweets he points to, Chris is the one starting with look at sea. And it's the it is another very classic visual illusion that's very strong, where basically a bunch of horizontal lines really look as though that they're diagonal basically. And they're just not it's very, very strong. Joe Henrik says that you probably see the lines of sled slanted you do but he would I think

argue that he says most him but don't see that so um I mean I don't know right I don't know the research I haven't I haven't done a cross-cultural study with that but if I had to bet money on it I'd in my ignorance I would kind of suspect that that is pretty culturally constant, that illusion. Would that be interesting to find out? Oh, okay. Well, you can, you can do your, you know, your betting market tick on that.

And I, we will probably have a chance to speak to the offers of this paper. So it's a, it's a good thing. We like that, but yeah, no, the the the other thing here is I again on the sociology of science kind of thing that in in Chas Firestone's response to this, he does things like he says, we didn't miss site this. Here's a picture, you know, so this is a good chance to clarify this kind of thing. And at the end of the thread, he mentions, what's next? We're happy to know that Henrik and colleagues share our concerns about the Seagulls' data

quality. Their previous writing had given a different impression. And he puts up helpfully quotes where they are saying very positive things about it. But in the thread, Joe Henrich says that they've been worried about the data collection as well, right? So he says, we hope our discussions of key pitfalls chart a productive path forward. By contrast, we're less interested in speculation about who has read what, is aware of what, rushed what off to where. Not only is it materially irrelevant, best to just focus on the arguments,

but it's also false in every case below. We hope future exchanges leave the site and they point to previous interactions and messages to people. Again, you know, this happens, right? Like researchers are people, egos are involved, things go back and forth. But I think that it's worth noting that this paper is just, it's a very well argued paper and it can be resolved, the debate around it can be resolved around, you know, high quality data collection. The evidence and the arguments.

Pre-registered. Yeah. Yeah. Well, evidence and arguments in the literature. Like if there are fundamental issues in the paper we just reviewed that people like you and me can't see. Aren't aware of, yeah. Yeah, because we're just dummies in this particular area, then someone else can write a really cool paper and change our minds again. That would be great.

You know what I mean? You don't need to get your nose at a joint about it. And yeah, having now just sort of scanned through Chaz Firestone's response, I think it strikes a very appropriate tone, I think I would say. I might. Yeah, I like the tone. I might recognize something in the tone. Well, there was some subtext there, but I think it was more genteel and polite than the thread they were replying to. So. Oh, yeah. Yeah, this is, this is right.

But you know, the other thing I will say is like, I came across this paper because of the exchange on Twitter. Then I read it. Uh, you know, we talked with Mickey a bit about it and then I read it in detail for this. And, you know, this is also like a little bit the sociology of science, right? Paul Bloom talked about this on this blog. Other people have been discussing it and whatnot.

And, you know, I think that is also something that is good, is like, even though there might be, you know, conflicts or whatever, researchers are gossipy bitches too. So they're like, oh, you know, what's this? People are arguing about it online. And, you know, that's also, it's's just we're humans. It's part of the fun It's part of the fun It doesn't have to undermine the sort of serious business as underneath it like I've got the same kind of argy-bargy

The same kind of ego stuff going on in my field we cast a bit of shade at each other and we go pretty hard and And it's all a good fun really you know like it's not it doesn't have pretty hard and it's all in good fun really. You know, like it's not, it doesn't have to be, it's good. At the end of the day as well on this, I like Joe Henrik's work and I put in general in this campaign and like his research covers a whole bunch of different stuff, right? Like he's, he's got a whole ton of different research lines, which are quite influential.

So like, if it turns out that this illusion isn't as culturally variable and it isn't attached to you Know the features of the environment That's all right, like it doesn't it doesn't therefore prove everything else ever claimed is wrong He's not gonna fall to his knees and go up wasted wrong. Right? He's not gonna fall to his knees and go up wasted. I curse you, Chaz. No, that's right. This is this is good stuff. Yeah, it'll probably spark a little bit more work and it might be resolved quickly or there might be some some more research. And that's what it's all about. Final comment from me, Matt, is I just love comparative psychology research It's always so clever like things that I wouldn't think of every day, you know that when we read that book about the

Octopus, you know studies as well. I kept thinking like I would never have thought of that way to Part of it. I'll just get my thumbs up. I Would never have thought to give an octopus a twirly-whirly. How did they think of that? Well, the one thing is I don't like so much where they cut arms off. No. No. I don't like that.

No, not you. We do not endorse that. No, me too. I like the comparative stuff because I like when we show that some very human thing is something that parakeets do as well. I really enjoy that sort of little pricking our human-centric, species-centric problems. Exceptionalism. Exceptionalism, yeah.

Yeah. Well, this was an enjoyable one, Mark. Good. According to academia, it covered all the different aspects that we like. The replication, crisis, psychology, cognitive stuff for you. All great. All good. Gossip on Twitter. It's got it all. Like I said, after reading the paper, I reached out to Dorsa and Chas if they would be interested to reached out to Dorsa and Chaz if they would be interested to talk about it. Because I think it's a really interesting area of research. So that will probably happen sometime soon and there we go.

Yeah, it'd be good to ask them some stuff, like not necessarily rehashing the paper, although we can a bit if we want to, but just ask them more about kind of what they think it implies or what yeah yeah bigger picture stuff yeah that's right now we can just force them to talk about gossip for us. We won't do that like who's your fine most hated side call? Who's your next target? He's your biggest rival. Yeah that's about next. All right, very good Chris. Enjoyed that. Thanks very much. Bye bye. You