 I'd like to begin today by acknowledging the traditional owners on whose lands we meet remotely today. So if you're in Canberra, that's the Ngunnawal people. And I'd like to pay my respects to Elders past, present and emerging. Housekeeping. So your microphone has been automatically muted on entry and your video won't show. So I won't be able to see you and other participants won't be able to see you either. If you'd like to submit a question, please click on the Q&A button at the bottom of the screen. And just a note, we don't have a moderator for this session. So we'll be looking at questions at the end, multitasking and dealing with those while we're speaking. And just also note that this webinar will be recorded and the recording will be made available after the event. You'll be able to ask questions or make comments via that Q&A tab, as I said. But if you don't wish your comment to be part of the recording, you can contact science at anu.edu.au after the event. I've put those details in the chat box there for you. Just let them know that you'd like your question removed in your recording before it's made available. I will share my screen with you. So this session is on discovering psychology, the science of the mind. And you'll have two speakers today, myself. I'm Dr Stephanie Goodhue. You can call me Stephanie. And later on in the session, you'll have Associate Professor Mark Edwards or Mark. We're both academics in the Research School of Psychology. So that means that we do both research and teaching. So we both teach in second and third year level courses. And just a note about our background. So as you may know, psychology is a very broad field and involves lots of intersecting sub-areas. Broadly, you can think of them as fitting into three main categories. So there's cognition and neuroscience. So that's looking at a lot of cognitive process, like how we think, learn, remember, and pay attention to information. And then you've got social psychology, which is more about intergroup processes. And that's often applied in organizational settings via organizational psychology. And then you've got probably the band that psychology is most well known for, which is clinical and health psychology, which often involves applying the content or knowledge from the social and cognitive areas under helping people who are in distress or have a diagnosable clinical condition. So both Mark and myself are from the cognition neuroscience side of things. And so you'll probably see that reflected in the content that we'll talk about today, which hopefully pique your interest. But just if you're wondering if that seems like it's just from one aspect of psychology, that is the case. So we don't have people from those other groups here today. So what I want to first show you is this stimulus. Just a note in this webinar format, I can't see you or hear you or your reactions. So this is a little bit different. So when I deliver this material in front of live audiences, basically, I'll imagine your responses as we go through. And I'll tell you when to be reading things out. So when you look at this on the screen, I want you to read aloud to yourself, what do you see there? Most people say, well, I see A, B, C. Seems pretty simple, right? Well, in fact, it's not quite so simple. What do I now show you this? And now if you read it top to bottom, most people say, well, now it looks like 12, 13 and 14. And this is really striking because this stimulus in the middle here, it's ambiguous. And so you can see it as a B or you can see it as a 13, depending on context. But what's particularly striking is your brain is making inferences or little decisions if you like about how to represent an ambiguous stimulus like that. But we're often not aware of those sorts of machinations or deliberations. For example, you probably weren't aware of thinking, oh, is that the letter B or is it the number 13 when you first read it across? You most likely just saw A, B and then C. And this shows that even in what seems like quite a simple stimulus, our brain is doing a lot of interpretation about what information is out there on our behalf. And that's really what psychology is about. It's about getting to the heart of some of those processes, many of which might have been even unbeknownst to us and we're just aware of the end product, like what you consciously perceive there or see on the screen. And we're looking at how to understand how those processes work and what factors might influence them. Now I want to show you a test of selective attention. This is a test of selective attention. Count how many times the players wearing white pass the basketball. How many passes did you count? Correct answer is 15 passes. But did you see the gorilla? This video is from research by Daniel Simons and Christopher Shabri and is copyrighted. It is available for use in talks, training and teaching on DVDs from VisCog productions. I want to double check on the zoom setting. Hopefully the sound came through. Okay, just going to share my screen again. Hopefully what you saw there is a phenomenon called inattentional blindness. So what that means is when our selective attention is really focused on one stimulus, it can be really difficult for your brain to be able to process other information. Which means that you can miss things that might otherwise seem really quite obvious or quite large stimuli. Like in that case the gorilla. It is often nicknamed the invisible gorilla. This is a really striking phenomenon because it shows how when your attention is selective on a stimulus or in a particular task, like you are trying to count all the passes of the ball there, you can miss something otherwise quite large and important. This is called inattentional blindness. Inattentional blindness is where our brains don't have the capacity to process everything in every given moment. So attention really serves an important process in selecting key information and often filtering out a large amount of information at the same time. This means that we can miss things that we are not currently attending to. Inattentional blindness demonstrates the power of selective attention and how we can miss things that might otherwise we think would be really obvious to see. What is inattentional blindness matter? Well, did you know that driver inattention and driver distraction are the leading causes of serious car crashes in Australia? Where serious is defined as at least one person being at least hospitalised. This shows us that being able to understand things like attention inattention are really, really important and have practical applications and practical consequences. So something like inattentional blindness offers us essentially an outcome that we can use to measure and process the influence of other factors. For example, if you want to know what the effect of doing another task is on the likelihood that you'll see an unexpected stimulus, then you can use inattentional blindness to do that. Just got to note that it looks like my screen is not sharing. So I'm just going to double check that again. Okay, so what I want to show you now is another phenomenon. What you can see here is just a bunch of words on the screen and the task that I'm going to give you is to read aloud, not what the word says, but what colour is shown in. For example, this one here is physically yellow. So you're going to read out the word yellow. Okay, and we can do that together. Okay, let's start. Yellow, blue, red, orange, green, black, purple, pink, blue, yellow. So if you're reading aloud there at home it probably found that quite simple, quite straightforward. If you're fluent in English, that is not a difficult task to do. So now let's do the same thing again. I'm going to show you another set of stimuli and I want you to do the same thing. So remember you're reading the colour of the word, not what the word says. Green, red, brown, blue, pink, orange, green, purple, blue, purple. Hey, if you're reading along at home probably like most people, like I was just then, you're finding that a little bit more difficult. You find yourself hesitating more and you might make more errors and accidentally say the wrong thing. Okay, so the first one is really easy and then the second one you find really a lot more difficult. And the key difference between the two is whether there's a conflict between what the word says and the colour that it appears in. So in the top one we have, for example, the word yellow in the colour yellow and down here they're conflicting. You have the word yellow but it's in the colour green. And what you find is that people if they're fluent in English or whatever language the words are shown in, they're going to get much more interference as gauged by more errors and slower response times when you have this conflict. And what it shows is that you basically can't help but read the word. Reading is such an automatic process when you're fluent in a language that even though reading is basically your brain interpreting a bunch of fairly arbitrary stimuli to mean something, when you've done that so much and so many times, it's so ingrained that your brain can't help but do that. Even though you're trying to do a different task, in this case you can name the colour of the text or the colour of the ink and even though that process of reading is actually making it harder to do that task. What is the Stroop Effect? The Stroop Effect is what we just showed. So it's that increase in errors and increase in response time in the conflicting condition compared to when the colour and the words matched. So in literate adults, word reading is such an automatic process that it is even when it's not helpful to the task at hand. So you really just can't help yourself but read the word. And the Stroop Effect shows this by examining those increases in errors and time taken to do the task when there's a conflict between the word and the colour versus when they match. So why does the Stroop Effect matter? The Stroop Effect provides us with a really nice way of measuring automaticity. So how automatic a task is or process is. So how much it occurs even when it might be involuntary, like we might not want to do that process but it still happens and how much it still happens even when it interferes with other tasks. So then we can use something like the Stroop Effect as basically an outcome measure. So it can be used in conjunction with, for example, changes in context to understand how they influence automaticity. If you had a research question like wondering whether engaging in another task at the same time might impact automaticity, you could have people engage in another task in addition to doing the Stroop Effect of the Stroop Task to see how that affects the magnitude of the Stroop Effect. And the Stroop Effect has also been adapted to study some neuropsychological conditions, in particular one that I'm going to tell you about today. But as a lead into that, I want to ask you a few questions, aren't we, to answer the answer to them? And the answers can help to indicate whether you might in fact have this neuropsychological condition. Have you ever heard a colour? Have you ever tasted a sound? What colour is Monday? What colour is the musical note F sharp? If you answered yes to one or both of those first two questions and if you had a ready answer to the third or fourth question, then it's possible that you might have the condition called synesthesia. What is synesthesia? It's literally a union of the senses. That is, the word synesthesia drives from the ancient Greek sin, meaning together, and esus meaning sensation. So an individual who has synesthesia is called a synesthete. It has many forms and many varieties, but basically it amounts to where a sensation in one particular stimulus modality or type of stimulus elicits an automatic experience in another sensory modality. And types of synesthesia are named according to this format where they're named inducer and concurrent. So inducer is just the term for what induces or elicits a synesthetic experience and the concurrent is the synesthetic experience itself. For example, a lexical colour synesthete is somebody who experiences colour in response to words. Some of the most common forms include lexical colour synesthesia and the most common form is to have coloured days of the week. Since it's where Monday might seem blue, Tuesday feels orange, Wednesday yellow. For example, that's the most common form of synesthesia, but it's closely followed by the experience of coloured letters. And that's called graphene colour synesthesia. So graphene's being letters and digits. They're not mutually exclusive, so having one type of synesthesia actually means it's more likely that you probably have another. So a particular person might be both a lexical colour synesthete and a graphene colour synesthete, for example. There are all sorts of really wonderful and interesting varieties that are less common. For example, lexical gustatory. So this would be where a particular word elicits a particular taste sensation. Auditory tactile. So this would be where a particular sound, for example, a note at a particular frequency, might elicit a feeling of pressure on one's elbow. And pain colour is where different intensities or types of pain can elicit different colour experiences. Okay, the prevalence of synesthesia. So recent research has shown that the prevalence is actually much higher than people initially thought in surround 4% of the population. And also contrary to what people thought initially is actually equivalent rates in men and women. Often when you put out a call to the general public to recruit synesthetes for experiments, more women typically respond than men. And so that led people to think initially that synesthesia was more common in men but when you do sampling where you take a representative sample and actually figure out how many people in that sample have synesthesia then there's actually equivalent rates in men versus women. A really important distinction in synesthesia is that between associator and projector synesthetes. So one thing you might be wondering especially if you're not a synesthete when we're talking about having a colour experience in response to a word or a note is what do you mean by that? Where is this colour experience? Where is it seen or experienced? And the answer really depends on what type of synesthete they are. So an associator synesthetes sees or experiences for example the colour in their mind's eye. So it's sort of a more internal process. Whereas a projector synesthete perceives the colour is actually out in the physical world in front of them. So it could potentially be in front of other objects in front of them for example. An associator synesthetes are much, much more prevalent than projector synesthetes. So this diagram just shows you an example of a particular projector synesthete and what his experiences look like. So this is how he saw the colours and the shapes of the days of the week. So they had this particular spatial arrangement and these were the colours. And this is a diagram of where he saw them like out in space in front of him. So literally if someone said, oh, do you want to catch up with me next Wednesday, this is basically what his experience would then be. You'd see Wednesday in the context of the week out there in front of him like that. And these are some other diagrams of how he saw the months of the year arranged in an elliptical shape around him and also years making up centuries. So how does one come to be a synesthete? So it seems that people who are synesthetic have been for as long as they can remember and from what we can tell that actually seems to be basically from birth. So what's thought to happen to create a synesthetic brain? I should say there is a genetic contribution to synesthesia so it's not completely deterministic. But if you have a first degree relative who has synesthesia then you're more likely to have it than somebody else randomly from the general population. So what's thought to happen in the development of synesthesia is contrast that with the development typical neurotypical development in the human brain is that basically the human brain starts off with a really intense diffuse and large set of connections between different areas of the brain. And what happens through those early years in development is some of those connections are consolidated and to remain but a lot of those extra extraneous connections are basically sort of die out. It's called synaptic pruning. So if two areas don't communicate with each other a lot or close in time some of those connections might be more likely to die away than areas that are in closer communication. And what's thought to happen in the development of synesthesia is basically that this incomplete synaptic pruning. So what that means is some of those extra connections that in a non-synesthete would probably get dispelled during development, they're maintained in the synesthetic brain. And one piece of evidence that supports that line of thinking is, remember the graphene colour for the synesthesia is one of the most common forms. And it's interesting that the areas of the brain that are specialised in processing graphemes versus colours are right next to each other in the human brain. So this really supports that idea because if you think of two areas that are likely to sort of maybe keep a connection that might otherwise be pruned away it's more likely to be two areas that are next to each other. So I've just seen Ricky's question there, is there a Q&A at the end of the webinar? And yes, there will be. And so synesthesia was first introduced into the scientific literature way back in 1880 by Galton, so very early in a nature. And there Galton describes people who have what he calls the innate and predatory tendency to see numbers in particular arrangements in space. He was the first to identify the distinction between associator and projector synesthetes. So he describes some individuals as having experience out there in space, so projector synesthesia. Whereas others have it in a sort of what he calls a dream land with no strict connection with external space. So that's more indicative of an associator synesthetes. Okay, synesthesia initially fell out of favour as a scientific topic to study. And the reason for that is in psychology, we really want to take a scientific approach to things. And that means being able to measure the effect of very internal psychological processes, but being able to measure those in a way that's objective and verifiable and repeatable. And often that means studying the effects of those internal processes. But way back in 1880, there wasn't really many good methods or technologies available for doing that. And so it really left scientists wondering, well, is synesthesia a genuine perceptual experience? How can we verify that? Is it maybe people just being particularly creative and imaginative and the way that they're describing what might otherwise be a normal perceptual experience? There really wasn't ways to differentiate between those explanations. Whereas then there was a massive resurgence in synesthesia as a topic of study in the cognitive revolution in the late 20th century. And this is a movement in psychology. So broadly, historically psychology started out using methods called things like introspection, which is where you think and reflect about internal processes. So you might come to a conclusion about how your memory works by internal reflection. A massive problem with introspection is it's completely subjective. And if one person, one psychologist engages in introspection, it comes to one conclusion. And a different psychologist engages in introspection, it comes to a different conclusion. There's really no way of adjudicating between those different claims. And psychology sort of reacted to that initially with the advent of what's called behaviorism, which was a school of thought that was very much reacting to that and saying we really want to use objective measures. But they sort of arguably took that a little bit too far and they're like, we're not even going to talk about things like thoughts or feelings or any of those psychological constructs and we're just going to focus on behavior. So the sort of classic rats running through mazes, that's very much out of the behaviorist tradition. If you want to know about something like learning, they wanted to measure something objective, like how long does it take this rat to run this maze after it's learned, for example. And then the cognitive revolution in the late 20th century basically kind of got the best of both worlds and brought them together. They were in agreement with the behaviorists that yes, we want to study things objectively and use some of those great scientific methods. But rather than saying that we're not going to talk about those internal psychological processes, those are the things that we're really interested in. We are interested in thoughts, feelings, emotions, memories, how do they work. And with the newer technologies and something like neuroimaging that are available really allowed psychology to take on the objective measurement of those very internal, private psychological processes. And synesthesia really maps that development in the field. And so once those newer technologies of measuring things objectively, including synesthetic conceptual experiences, a lot of these sorts of topics gained a lot more traction and interest. Okay, so I'm going to talk briefly about three ways for measuring synesthesia. So I'll talk about the synesthetic strupe task, so an adaptation of the strupe task that we just did before. I'll talk about functional neuroimaging of synesthetes brains and structural imaging as well. As we saw before, the standard strupe task, this is where people suffer interference in naming ink colour when there is a conflict between the physical colour and word meaning. Whereas the synesthetic strupe is where synesthetes suffer interference in naming the ink colour when there is a conflict between their synesthetic colour experience and the physical colour that it's displayed in. Whereas somebody without synesthesia, if we ask them to name the colour of the ink of these words, they're not colour words to a non-synesthetic, so they would find both of these sets equally easy to do. It doesn't matter whether Thursday's in red or Thursday's in yellow to them. Thursday doesn't have a colour, so they'll be equally good during the task in either case. Whereas for a synesthetic, it really matters whether there's now a conflict or a match between the physical colour and their synesthetic colour. So if a particular synesthetic sees Thursday as red, for example, then they'll find it much easier to name the colour of the ink here when Thursday's in red than when Thursday's presented in yellow, and now they're getting a clash between their synesthetic colour and the physical colour. So because the strupe effect is using objective measures like accuracy, reaction time, or how long someone takes to do the task, the fact that synesthetes do show as soon as that strupe effect is a nice objective evidence that this is really an involuntary perceptual experience for them. And the other main ways that's really verified, because this is a genuine perceptual experience, is neuroimaging. And so basically these are tools for looking at the functioning of the brain in real time. And so presenting synesthetic participants with graphene, remember that's digits and letters, that elicit the subjective experience of colour leads to activation in the colour sensitive areas of the brain, B4 and B5. So we're seeing in real time in these synesthetic brains that the stimuli that they say elicit an experience of colour for them are leading to activation in the colour parts of the brain. Which is really nice evidence. And in fact, one study compared brain activation for people imagining colours versus synesthetic experience. Because one sort of question is, do synesthetes just have a really vivid imagination? Is this sort of experience maybe linked to that? And it seems that while there's some relationship, it's more than that. And they found that for both synesthetes and controls of people who didn't have synesthesia, colour imagery resulted in activation of the colour selective area of the brain in the right hemisphere. But stimuli that elicited synesthetic experience activated the left medial lingual gyrus, an area previously implicated in tasks involving colour knowledge. And this was true only for the synesthetes. So basically you're seeing a pattern of brain activation that was really unique to people with synesthesia. And this tells us that synesthetic colour experience is qualitatively distinct from just vivid imagery. So now I'm moving on from functional methods which show you an index of brain activity in real time to structural methods which are basically just looking at the structure, how the connections in the brain sit there physically, statically. And one way to do that is diffusion tensor imaging. And this is a method for studying structural connections between brain areas. And DTI has shown that synesthetes have greater white matter connections in the brain. And this is again, really, if it fits in nicely with this idea of incomplete synaptic proving, being the synesthetic experience. So an adult synesthetes brain does have more connections throughout it than someone who's not synesthetic. And moreover, greater connectivity in the inferior temporal cortex was particularly strong for projector versus associator synesthetes. Hey, so here, not only was there greater connectivity in the synesthetes brain, the amount of connectivity could differentiate between different subjective reports of synesthetic experiences, i.e. whether someone is an associator or a projector synesthetic. Okay, so to summarize this behavioural and neuroimaging evidence that tells us that synesthesia is a real condition and synesthetic experiences are measurable and more than just vivid imagination. Hey, but what's it like to be a synesthetic? Well, many synesthetes report enjoying the experience and considering it integral to their lives. Hey, synesthetes are more likely to be engaged in creative pursuits. And often the synesthetic experience is quite integrally linked to that. For example, there are some synesthetic artists who might listen to a symphony and they're painting the colours that they're experiencing in response to those sounds at the same time they're an artist. Okay, so there can be quite an integral link between the synesthetic experience and their creativity. And synesthesia seems to be able to confer some advantages in, for example, memory tasks. Hey, what does synesthesia tell us as psychologists? Hey, it tells us that the identical physical world can elicit truly different internal perceptual experiences for different people. Hey, it's really easy and people often do take for granted that if we're looking at the same scene or the same stimuli out there in the world then we're going to have roughly the same perceptual experience in our minds and our brains. And synesthesia is one example that really undermines that assumption. And, for example, even just a word presented on the screen can elicit something really qualitatively distinct for some people that other people aren't experiencing. Okay, and the fact that we do really take this for granted that we have some kind of shared perceptual world, a testament to that is how many people reach or how many synesthetists reach adulthood before they realise that this experience isn't universal. Hey, so when I presented this in lectures on public talks on synesthesia before, it's not uncommon for adults in the audience to say, are you for real? This is a thing. This is not something that's a universal experience. You mean people don't see Tuesday as orange? It is really kind of shocking and surprising to them to find that what they experience is not something that everybody else experienced. And I think the fact that people can reach adulthood before realising that tells us just how little we might spend talking about our perceptual experiences with one another. Hey, how this represents the approach of psychology more broadly? Hey, so it involves applying the scientific method to understand very internal mental processes. And that's really what psychology is all about. Hey, as psychologists we seek to understand how individuals differ from one another and the richness and the diversity of these individual experiences. Hey, psychology applies in any context that involves people. Okay, so that is many, many contexts. We'll talk a little bit more about studying psychology at the ANU later on, but now I'm going to hand over to Mark Edwards. He's going to tell you a little bit more about how we see the world. Thank you for that, Stephanie. So, Stephanie was just saying we have our own internal main steps of the outside world. So, what we're going to look at now is how that occurs. So, in terms of what the brain needs to do, you can think about it in terms of these main steps. So, the idea that what you have is the object out of the world. That's what we want to see. And what we've got to go on is the image that is put up on our retina. In other words, on the back of our eyes where we have the photo receptors, how we see the image. So, we've got the object, it casts an image on our eyes. We then have brain cells that encode that information. In other words, a sensory representation. It's a response of photo receptors and cells in the brain that represent that information. And then at the end of the process, what we have is a percept of the outside world. And of course, what we have to go on is the retinal image. But what we want to perceive is what is actually out there in the outside world. So, in terms of thinking about this process, you can think about it in terms of, is the brain active or passive? So, do we passively perceive that retinal image like a camera does? Or do we, at least in part, actively construct it? So, obviously, it's actively constructed. Otherwise, it would be way less interesting than what it is. So, let's look at a few examples to show how active the brain is. So, one example is this one here. So, what are we looking at here? So, at first, it looks like a series of light and dark patches, not much. But if you look at it for a while, hopefully what you'll start to see are some forms, some objects start to appear. So, for example, around here, what we have is a dog, a Dalmatian. So, the head of the dog is here, the front legs, the body of the dog, hind legs, head down, sniffing away, walking towards the tree. Okay. So, what is that telling us about how the brain works? So, what it's doing is taking, in this case, a really degraded image, but then trying to make sense of it. Instead of just seeing things in isolation, it's trying to grip them into meaningful holes. So, what we're looking for are patterns. So, that's why when you look up at the sky at night, instead of just seeing stars in isolation, you tend to grip them into shapes. Okay. So, the brain is trying to make sense of the outside world by gripping fragmented things together to form objects. So, what about this one here? This is a simple one, but I think a really powerful one. So, if you look at it for a while, your percept of it, how you perceive it, how you see it, should change. You should alternate between these two percepts. So, what's happening here? We live in a three-dimensional world. Therefore, what we want to perceive is that sense of depth. So, not just height and width, but also the depth of objects. The information about depth in this image is ambiguous. It is consistent with either that depth arrangement or that one. So, what this results in is what's called a bi-stable percept. The brain alternates between the two. And it's interesting that we don't really have much control over that. It just does its thing for while we see this orientation and then we see that orientation. So, for the identical retinal input, so for the identical image on our eyes, we perceive two different things depending upon how the brain interprets that information. And then you can ask the question, would it actually be a good thing if we directly perceived the retinal image, the image on our eyes? Okay. And a good way or an easier way to think about this is to imagine the percept of size. So, when you see a person out in the world, how big do you see them? So, if our percept of size was based purely upon how big the image was on a rise, what would happen? So, what would happen is that the size of the image changes as you get closer to that person. So, we can see that here. So, what we have here is this chromatic drawing. So, let's think of this as a cross-section of the eye. So, we've got an object out in the world. It casts an image on our eye. If that object gets closer, that image gets bigger. So, what would that mean? It means that if our percept of size was based purely upon how big the image was on our eyes, objects would constantly be changing their size as we moved around in relation to them. So, as you started walking towards somebody, that would suddenly appear to get really big and then also get really small as you walked away from them. Okay. So, that would be a bad thing. So, it might be fun for a while, but if you had to live your life with that going on all the time, that would get really challenging. Okay. So, what the brain does is to actively interpret the retinal image in order to perceive the outside world. So, as we said before, the retinal image is constantly changing. The images on your eyes are constantly changing. We don't want to perceive that directly because if we did, what we would see of the outside world would be constantly changing. What we want to see is the typically unchanging or constant objects out in the outside world. Okay. So, there's a range of different constancies who look mainly at size and shape, but you also have lightness and colour. So, an example of lightness here. So, for example, you look at this scene here, yep, or the different perceived brightnesses. So, these light squares all appear the same and brighter than the dark squares. But, of course, you've got this little grid pad in here and this region here is in shadow. So, the actual reality is that these two squares are the same physical luminance. So, they're the same physical brightness, but you see them as totally different luminances. So, in other words, the brain is saying that, okay, even though the physical amount of light coming out of those regions is identical, I'm going to perceive them as being different. This one is being brighter in part because it's part of a pattern, but also because it's in the shadow of this object. So, I know that things in shadow, there's going to be less light coming off it. Therefore, I'm going to perceive it brighter than what the physical information is telling me because of it being in shadow. Okay. So, therefore, how do we generate a perceptive size? So, the size of the retinal image comes into play, but what we also do is to factor in an estimate of how far away the object is. So, again, go back to this little cross-section of the eye and what you can see is different size objects at different distances can cast the same size image on our eyes. So, we don't want to directly perceive the size of the image. We want our perceptive size to correspond to what's actually out in the world. And as you can see, for that same size image, the further away the object is, the bigger it must be. So, therefore, what the brain does is to take the size of that image and scale it by how far away it estimates the object to be. If the brain estimates it to be further away, we're going to perceive it as being bigger. Okay. And as we'll know in a few minutes, perceived size can also actually be used as a cue to distance, which can make things even more confusing. Okay. So, therefore, illusions of size. So, therefore, when we misperceive things, typically, what is the cause of that? So, the size of the retinal image, not that hard to work out for the brain. So, it basically comes down to misperceiving the distance to the object. So, let's look at this example here. So, we have an image of two people sitting in chairs in a corridor. Here we have what's called monocular cues to depth. So, cues to depth or to distance that we can get using the information from one eye. So, perspective information, and that's telling us that this person is further away than this person. So, now, let's imagine we took that person and put them beside them here. So, they're at the same distance. How big would that image be? So, let's say, you've got options one to six. So, if you put that person back here, side by side, would that image go up to one, two, up to six? On occasion, when I give this talk, people say, well, you are psychologist. Therefore, you're trying to fill me. So, I think it's actually even bigger than six. But if you do it, you'll find that it goes up to one. So, you can see once they're now at that same simulated distance, this person looks way smaller than what they do here. Again, the reason for that is we are scaling the size of the image on our eyes by an estimate of distance to the object. Here, we've got perspective cues. Therefore, we scale that size up by a greater distance than what we do here compared to this one. So, we perceive it as being bigger. Okay? So, again, we don't directly perceive the size of the image on our eyes. We don't want to do that because it would be constantly changing. So, what the brain has to do is to take the image on our eyes and then actively interpret it. Factor in cues, for example, like this, to distance to generate a perceptive size that hopefully corresponds to what the actual object is out in the world. Okay? So, therefore, as we said, illusions of size typically occur when we misperceive the distance to them. And Julian Beaver is particularly good at doing street art where he uses these cues to distance to get different distortions. So, what we have here is, Julian is not teeny-weeny, but what he's doing, he has drawn this image here on the pavement such that it looks like it's sticking vertically upwards. So, what's happening here is, obviously, he's a lot further back than this woman here, but given his relationship to that image, the way that he's drawn that image gives the appearance that it's sticking up vertically. So, what you're doing is the brain thinks he's at the same close distance rather than the reality of him being far away like these people. So, you see him as being massively small. Okay? Another example is this one here. So, he's so when you're looking at objects that are flat on the ground, you have those perspective distortions. You can see them here. So, parallel lines tend to converge in the distance. So, if you have perspective distortion on images, that tells you they're lying down flat whereas if you have no perspective distortion, that's an indication that they're sticking up vertically. So, what you do in this situation is you add distortion to the image to counter the perspective distortion such that now when the brain sees it, it says, okay, there's no distortion there. Therefore, what it must mean is the image is sticking vertically upwards. The same thing is done with signs on football fields. So, that's how you get them to appear to stick up vertically. But then when you look at them from the other direction, now perspective distortion and the distortions you've added to the image are working in the same direction so it looks massively distorted. Okay? Another really neat one is this one here. So, size and shape distortions go hand in hand. They're two sides of the same crime. So, the illusion here is what? What do you think it is? So, it's actually that these two table tops are the same physical shape. So, in most cases when you know what the illusion is, you can look at it and think, oh, yeah, that makes sense. But in this case, you go, no way, they've got to be different. When I give this in lectures, I actually use a document projector so I can use a physical bit of paper, but now we'll have to simulate it. So, bouncing between these two, they are the same physical shape. What's happening is that we have perspective information in this image. So, we're getting different depth cues in it. So, we're scaling the size and shape of these images accordingly. So, these two identical physical shapes appear to be markedly different. Okay? Finally, what we'll look at is the nature of these assumptions. So, what I've just said is that the brain interprets these images, the images in the brain to generate a percept that hopefully corresponds to what's out in the world. So, at what level in the brain does this occur? So, let's consider this in relation to the moon illusion. So, hopefully you all know what the moon illusion is. So, that's when the full moon, just off the horizon, looks really big and a lot smaller when it's up in the sky. It's an illusion because if you actually take photographs of the moon, so as it goes, it's above the horizon, it stays the same physical size. But hopefully you've seen it the case that when it is just off the horizon, it can look really huge, but a lot smaller up in the sky. So, let's think about it from a size-constancy perspective. As we said, the physical size of the moon stays the same, so the size of the retinal image stays the same. So, therefore, why are we perceiving the big moon off the horizon? So, for size-constancy to account for this, the brain must be making the estimate that the full moon, just off the horizon, must be a lot further away than the moon up in the sky. So, the cues to distance is filling the brain into thinking that it's further away when it's just off the horizon compared to when it's up in the sky. So, that would be the size-constancy explanation. It's not a new explanation. It goes back at least to Ptolemy 200 AD. But then, back in 1940, scientists called Bordering, which is an unfortunate name for a scientist, but he did was to run an experiment where he explicitly asked people to predict the distance to the... or estimate the distance to the moon. So, they said, okay, the full moon just off the horizon. That looks really huge. Therefore, it must be a lot closer. So, in other words, he got the exact opposite results. So, one could take that as evidence as he did against this theory, but the counter is that these assumptions about distance that create that percept are based on subconscious inferences. In other words, they occur at a subconscious level. We're not aware of what they actually are. And then they can lead to the percept of differential size. And then what we can do at a conscious level, think, well, that moon looks really big there. Big things tend to be closer. It must be a lot closer than the moon up in the sky. Okay? So, what it means is these assumptions that the brain used to interpret the retinal information to interpret the image in our eyes occur at a subconscious level. We are not aware of them. And for quite a while, a lot of psychologists were trying to work out what are the different assumptions used to interpret the retinal image. And is there a hierarchy? Some assumptions more important than others. And also, the interesting thing is conscious knowledge does not affect them. So, even if you know the reality. So, for example, with the moon illusion, the distance to the moon doesn't change, depending upon if it's off the horizon or up in the sky. So, you know that at a conscious level, but it doesn't affect you getting the illusion. Same as the AIMS room. So, hopefully you've seen that, if not Google it later on. So, that's where you see people in a room. The room is actually distorted, but the brain thinks that it's rectangular. And therefore, the change in image size that occurs when they move around in it, because they're changing distance from you, it's actually interpreted by the brain as them staying at the same distance, but suddenly getting bigger or smaller. So, when you look at an AIMS room, two eyes open, binocular depth cues, you see what the true shape is. So, you know, okay, yep, it's not square, it's not rectangular. It's some sort of rhombic shape. But then, when you close one eye, remove those accurate depth cues, you will then get the illusion. So, again, conscious awareness, knowing what the reality is, doesn't interact or doesn't stop the brain making those incorrect assumptions. So, given that, how can the information be encoded so that we don't have cognitive access to them, either to know what they are or to change them? So, one way that we'll talk about, for those of you who do psychology at ANU and do Stephanie and Mai's 30-year course, we'll talk about it in terms of neural networks. So, that's a grip of cells in the brain that are solving a particular problem, and we'll talk about it in the example of depth perception. So, using information left eye, right eye, so, stereopsis to work out a person of depth. In order for the brain to implement stereopsis, it's got to make assumptions about the outside world, but the way that it encodes those assumptions are via how those brain cells are connected to one another. So, the patterns of excitation and inhibition, so, which cells, if they're firing, enhance the activity of other cells versus if they're firing, suppress the activity of other cells. So, it's those patterns of connections between the cells that encode, that implement these assumptions about the outside world. Okay? And then finally, the other thing to think of is failure of size constancy. So, if you look at people in cars from either a very tall building or low-flying aircraft looking out the window, people look really small. The reason for that is we have very limited cues to distance under those conditions. So, when you strip out those cues to distance, the brain can't scale the images correctly. Therefore, it's forced to just use the size of the retinal image. Okay? And then to wrap it up. So, what we've talked about here are perceptual illusions. So, that gives us insight as to how the brain works, how it interprets information. You also have what's called sensory illusions. So, these are ones that are due to the properties of cells. So, if you like, it's more like a hardware fold. So, it's due to limitations in how information is encoded. So, for this one, you should get little gray dots of light at the crosses here in your peripheral vision. Similarly here, you get little black dots appearing even though there are no black dots in the image. And you also get lots of different color illusions because of the way that the brain interprets information. And interestingly here with this one, I'm sure you've all seen. So, this is a really interesting illusion because with most illusions, people see the same things. Even if you get ordination, you ordinate between two states. This one, though, people see different colors. Either gold and white or tip-all blue and black. And the reason why people see that is still being debated. But it's most likely due to color constancy and subtle differences in color constancy mechanisms between different people. Okay, so that was a very quick run through how the brain produces that percept of the outside world. Don't really expect you to fully follow it. But just to give you a feel of the sort of questions that you can ask and the sorts of things that you can study doing psychology. So now, quickly, we'll be back to Stephanie. Yep, I'll just be quick because I'll leave enough time for Q&A at the end. But honestly, psychology is popular because it is so interesting. It's about people and what makes us tick. So it is just intrinsically fascinating. And as consequence, it's also really widely applicable in a whole bunch of different domains. I know many people pursue psychology because they want to be a clinical psychologist and that's a very noble and worthy pursuit. And a psychology good degree is the first step in your training to become a clinical psychologist. That's what you'd like to do. And they really recommend that you come and study psychology with us at ANU. So all of the academics, all of the people that you'll be interacting with and your learning experiences are really passionate researchers as well as educators. And why that matters is psychology, like most sciences, knowledge is just moving forward at a really rapid rate. And so often by the time something is out of textbook, it's already several years old. So by learning from researchers, you're learning from the people who are actively creating and understanding that new knowledge so you'll get it hot off the press. And we'll also be able to teach you in those skills for how to pursue research questions and how to create and how to understand new knowledge as you encounter it. Which is what you'll continue to do throughout your career after you leave university. In psychology at ANU, we really offer many opportunities for small group learning with academics, for example, through labs and small course enrollments. And that's really important because obviously you come to university to learn. But a lot of the connections that you make at university can be really important throughout your life. So both the ones that you make appears for the other students and also the ones that you make with academics. So academics can be really important mentors and advocates for you throughout your career. And so this gives you the opportunity to make those connections. And just an example, Mark and I are running a special topics course this semester for third year students. So we've run an entire course just tailing around those two students. So to us, you're not just another number. You're not just another face and a sea of faces in a lecture. We really want to get to know you and to help you to have the best learning experience throughout your degree and beyond. So I'll leave the content there and we'll move on to Q&A. So just a reminder if you want to ask questions you type them in the chat box. So an anonymous attendee has asked, hi there, I'm interested in implying for master of professional psychology. I would like to know usually how many students you take every year. What I'm going to do for that question is quite a specific one. I'm going to pop my email in there. And if you'd like to email me, I can put you in touch with the people who administer the MPP program who can answer that sort of more directly and the most up to date information. Okay, so we have other questions. I'm just going to stop screen sharing as well. Hey, so just a reminder, I'm going to just type the question in the Q&A box if you've got any. For psych honors, is there the opportunity to be interdisciplinary? Yes, honors is a really exciting part of the degree. So for those of you who don't know, this is basically a fourth year of the degree where you do both advanced coursework but also an independent research project which is supervised by an academic member of staff. So yeah, there's lots of really exciting opportunities for different research projects, including ones that could be potentially interdisciplinary. Hey, any other questions? Oh, for ANU students is the internal application through UAC. So for applications, I'll pop in the chat box the relevant contacts for that and that's so that they can give you the most up to date and current information. I don't want to tell you something that isn't as up to date as it could be or since it's being recorded even if it's accurate now might not be in a few weeks time as things change. So there's a link to a website there, have a look at the FAQs. If it's not clear from that, there's contact information on that website for them to be able to answer your question directly. Any other questions? Okay, we might leave it there then. So I just want to thank you all for attending. I hope that this gave you a flavour of at least some of the sorts of things that you can look at through psychology and I really hope that we get to see you all in the future when you're enrolled in psychology.