The Neuroscience of Magic - with Gustav Kuhn

[Applause] thank you very much do you remember the first time you saw a magic trick that maybe in an uncle making a coin appear from behind your ears or a silly trick like this I love magic and I've spent most of my life dedicated to this weird world of deception and illusions in the first part of my career I used magic simply to entertain people in the latter latter part I've been using magic as a way of uncovering some of the secrets of the human mind because magic allows you to experience the impossible but all of the magician's I know they don't have supernatural powers instead they are tricking your brain and hijacking your perceptual systems which allows them to manipulate how you experience the world around you and as a scientist I'm particularly interested in these tricks because these tricks and mine hacks can provide us with unique insights into how the brain works so I'm the man I'm the director of the magic lab at Goldsmith's and we've used magic as a way of exploring lots of areas in psychology we study misdirection and mind-control techniques to understand consciousness and free will we apply a lot of these principles to the outside world as well so for example we are teaching robots and artificial intelligence agents magic tricks to try and understand what would happen if machines start to deceive humans now this all sounds very scary and may result in our spending less time on this planet but don't worry we also use magic as a way of enhancing people's well-being so we'll all die feeling much better about ourselves so tonight or no today normally it feels very dark in here this afternoon I would like to give you a brief glimpse into this world that brings together art and science and to start off with he would like to see some magic yes so let me start off by performing the oldest trick in the history of magic and this is known as the cups and balls I've got two cups can you just check out one cup here you can hold your hold hold onto it and make sure and this one over here you can check and two little balls here check out these balls great solid cups any rabbits pigeons lions inside no shame that would have been really cool and these two balls nothing has happened to these no so two cups two balls and of course the most important thing my magic wands oops don't worry there's always another one just about down here so watch very carefully I just waved a magic wand and the ball disappears this of course is all about misdirection so the keeper secret is to keep an eye on the ball I said to keep an eye on the ball because the ball is still over here so one more time I just waved a magic wand and a ball disappears from my hand flies all the way through the room into your pocket you sitting there you said would you mind standing up stand up check your front pocket know your trouser pocket but of course the ball doesn't stop there because it flies all the way back through the room and reappears back under the cops [Applause] now watch very carefully how this ball travels from here to here and likewise this one travels from here to here they have both changed places you're clearly not very impressed by this so one more time I'll snap my fingers and ball number two doesn't fail travel all the way right over here so better watch carefully how this ball penetrates this Cup even though these cups are completely solid oops it's a visual illusion okay none of this is real as tricks its tricks and so one more time salat three solid ball number two penetrates these cups is that is that too complicated in a little bit complicated let me simplify things by getting rid of one of these balls or actually because it's you I'm gonna get rid of both of them the secret is the ball is still under the cup okay you're gonna have to pay more attention because it goes into my pocket reappears under my knee it goes through the top of this cup just snap my fingers and there - this is too fast am I losing am I losing you I was told to speak up and would you like me to do this in slow motion okay just for you at you three a number one number two and under which of these you'd like under which of the cups would you like the balls to reappear card number one or cup number two do you change your mind no cup number two that's the wrong choice because there's already thank you well wait wait wait of course this wasn't pure coincidence because the chances of you selecting to cup at the lemon where 150 if not 200% thank you so I'm the director of the magic lab at Goldsmith's and I'm intrigued by the emotions that magic elicits as well as the tricks that magicians use to manipulate how you experience the world so let's start off by asking the question well what is magic now rather intriguingly magic is one of the oldest art forms and let yet unlike most other art forms it's very pure we very poorly understood and indeed research on our experience of magic and the tricks that magicians that use it's been very recently has only been for the last sort of few decades that scientists and magicians have tried to come together to try to answer a lot of these very important questions because magic deals with some of the most fundamental concepts in in psychology deals with perception consciousness free will deception beliefs and yet we are only starting to understand some of these questions so what is magic well I think of magic as creating a conflict in beliefs it creates a conflict between the things that you are experiencing and the things that you know to be possible so you all know that lemons can't appear out of nowhere yet hopefully that's exactly what you've experienced and so magic is about creating this conflict in beliefs between the things that you know about the world and the things that you just experiencing as scientists were interested in some of these experiences and a few years ago we carried out a neuro scientific study to try and understand the neural activation of people experience when they're watching these types of magic tricks and we use an fMRI scanner which allows us to measure people's brain activation whilst they watch different types of magic tricks and we scan their brains while still in this scanner and the results are truly remarkable because then if we look back here this is a diagram of the brain and you can see there's two main areas that have been activated whilst people watching these magic tricks one of them known as the dorsal lateral prefrontal cortex and the other one known as the ACC what's very interesting about these results is that these are areas that are generally involved in this type of conflict because we are constantly in conflict with ourselves so at this point in time you might want to listen to what I'm saying yeah at the same time you being distracted by your neighbor coughing that creates a conflict we have these conflicts all the time and what's intriguing is that the brain areas that are associated with processing this general conflict overlap very closely with the brain areas are activated whilst we are watching a magic tricks and that gives us lots of confidence to suggest that really at the heart of magic is a cognitive conflict between the between the things that you experience and the things that you believe to be possible but at this point I'm gonna have to be really honest with you okay I know my look like it but I really don't have any supernatural powers so how is it then that I can create these experiences in your mind well to do so I use psychological tricks now you psychologists psychological tricks that are truly remarkable and very very surprising and this is what I would like to focus on for the rest of this lecture so how many of you would like to make a rabbit disappear are you up for little experiment yeah so you should all have a piece of paper which is not like this but looks somewhere like this you should all have one of these and on the back of this there's you can see a little of rabbits inside the top hat you should do all have one if you don't you can maybe share it with someone else and what we going to do is we are all going to make this little rabbit and the top hat disappear and I'm going to give you instructions on how you do this you close one eye I'm going to remove my glasses because I find it easier I'm gonna close my eye one eye my left eye stretch out the piece of paper and look at the cross so stretch it out one eye closed the left eye closed keep your eye on that cross and then gradually bring that paper closer and closer without moving your eye and at some point that rabbit and top hat will disappear for me here is gone now as soon as you move your eyes it will come back but if as long as you don't move your eyes and you get the sweet spot that rabbit will disappear have your God there how many of you are really disappointed okay now with a lot of these tricks the explanation is a lot more fascinating than the trick itself hopefully all most of you manage to get that rabbit to disappear if it doesn't disappear keep the piece of paper and to tried tried during the tea break or at home so why does this illusion work well to understand the illusion we need to know understand a bit of an understanding of how the visual system works so what I have here is a diagram of the eye and you can see a person outside in the world the image of that person's projected through your lens onto the back of our eyes which is known as the retina and the retina is covered in thousands of little photoreceptors that I will ink all of the visual information and then send it through the optic nerve to different parts of our brain that do all of the visual processing does that make sense yeah now through a little fluke in evolution there's a bit of a design flaw with our eye can anyone spot a design flaw what's as a fossa floor well most people say upside down but actually once you saw once you start looking at the the visual system turning an inverted image upside down is a piece of cake that is really very very simple I know it's puzzling but once you understand the complexity of vision that is a really easy task to do what's another floor though what's a big floor as an engineer the optic nerve so all of these neurons have to leave our retina through the optic nerve which means we don't actually have any photoreceptors on that optic nerve and what this means is that any information that is projected onto the optic nerve what we can't encode it and so it's never there and that's how this trick works so if once you get the distance right and once that rabbit projects onto the optic nerve the rabbit will simply disappear but I promised you a miracle that's not the miracle yet this is the really amazing thing how many you've noticed this blind spot we don't and even if you close one eye and look around the world you don't see it I've told you about it you've experienced it yet we simply don't notice it it's big it's about that size okay I mean you just saw it I mean this is a big spot and yet of course we don't notice it and the secret to magic involves exploiting lots of these blind spots do you want to see an even bigger one okay let me tell you about my favorite one we move our eyes about three times per second and during each of these eye movements visual system is blind you're in darkness and again you can either trust me or you can try yourself so next time you go to the toilet or you're standing in front of a mirror try and spot your eyes move you can't if you can send me an email and often and I'll pay you a thousand pounds he simply can't see your eyes move and again from an engineering point of view that makes a lot of sense because if you trying to take a picture with a moving camera you get a blurred image and that would be completely pointless anyway and so instead the eyes the visual system shuts down during these hundred milliseconds or so during which you're making a noise you're I'm ease but are you noticing this you notice amazed at any of these no now you might think well that's not that much but um let's do a little bit of mass during each of our movements we are blind for about a tenth of a second or 100 milliseconds we are said before we make about three eye movements per second which means pedegg you make a hundred and fifty thousand eye movements multiply that by a hundred milliseconds you end up with four hours which means that a quarter of your day you spend in darkness and yet we're oblivious to this darkness do you want me to take it a bit further so now I've Illustrated this blind spot the fact that you spending a quarter of your day in darkness but even for the moments where you do actually feel you are seeing things well you're far less observant than most people think they are I mean how many of you have have you got any good observers in here who thinks they're pretty observant yeah got a few okay let me are going to give you a little test okay how many of you played spot the difference yeah okay so this is gonna be a bit like a spotter two difference I just did this this morning it got a nice picture here of the Royal Institute the hallway coming and we're going to play spot the difference but rather than having the pictures next to each other I'm gonna alternate between the two pictures and would like you to do is hold up your hand when you spot the difference okay don't shout it out if you give you spotted don't shut it out just hold up your hand especially and I'm gonna watch especially those really good observers of you okay you ready okay let's go come on come on I know tea break is coming but I'd expect a little bit more come on you know getting it check out the picture up here okay ah pretty obvious isn't it well of course it's obvious once you know it but if you don't you're blind to it now even now as you're looking at there you're laughing how could you've not have noticed this in the first place and the reason why you don't see this is because you're not paying attention to this and so unless you're actually attending to something you simply won't see it and the key to mister and you might think well okay this only happens in this artificial context here and it doesn't this is a lovely study carried out by Levin and sherry some sonship risk some Sun Levine awhile ago where they asked and a volunteer here for directions on a knee or on an American campus and just watch what happens so they're having a conversation you can see that the lady is looking at the guy wearing the Hat they're having a nice conversation and yet and yet she fails to notice that the person has changed now here you're laughing oh well this could only happen in America it doesn't I had a PhD student who carried out studies as Spitalfields market here in London weather changed a person for a mannequin and most people did not notice that they were talking to a mannequin and so intuitively we believed that we should be aware of all of these things that are going on around us and yet we simply don't like with the blind spots or the blindness that you'll find yourself during most of your daily life your awareness of the outside world is much more impoverished than most people think so how does this link to magic well of course as a magician I try and exploits a lot of these limitations and we do this to try and understand why people fail to see these really obvious things in their environment and I'd like to do now is just give you a little bit of a demonstration of how we study these principles in the laboratory and I'm just gonna clear a bit of space here and also this is such a beautiful auditorium isn't it can you all see really well yeah it's amazing visibility which as a magician is really really rubbish okay so I'm not sure whether this is gonna work for a lot of you it's gonna work for you guys here yeah you're gonna have a little bit of a more privileged vision of this but this is a purchase and experiments not a magic trick is an experiment on misdirection and I'm gonna just this pretty quick okay it's not very long um I just like you to watch and observe are you ready yeah come how many of you did not notice how the lighter disappeared Wow most of you you guys saw most of it yeah we should we all laugh at those over there you ready for that would you like me to show it again yeah has anybody know the lighter don't worry I've got another one got another one here so I'm gonna do exactly the same thing again now before we continue just remember that ah okay it's very very important remembering it so how is it done well this is not a magic trick because the magician's wouldn't do this but we use these kind of things to study misdirection in the lab and so here I'm using lots of different misdirection principles to misdirect your attention we've got a bright light which will hopefully grab your attention I'm using movement to move your attention from the light over here this is the point at which I'm going to drop it so I'm using everything I'm using my social gaze so where I'm looking the sound the movement everything put together to hopefully prevent you from seeing this drop now I mentioned at the beginning that the gaff is really important because magic only works if you're unaware of your limitations and of course here you're not aware of the limitations intuitive you think well surely I should be seeing these things because they're happening right in front of your eyes and yet you simply don't now what I'm going to try and do now is give you a bit of a demonstration a further demonstration of how we study this in the lab and I'm gonna ask Pete to come and help me here this is truly a proper demonstration Pete can you just please give Pete a hand of applause for us for helping out and when magicians say they're doing an experiment they're lying because they always know that it's going to work this is science I don't know but ever it's going to work so Pete would you mind I've got a chair here would you mind just having a seat here so in the lab I often use eye tracking to try and study people's eye movements and you can hopefully see on the screen here so what I have here is an eye tracker and Pete if you just put this would you if I give this to you don't break it it's very expensive it looks like a pair of glasses but what we have here is a two camera so we've got one camera in the front here Pete can you just can you all give Pete a big wave so you can all see yourself waving and so we've got one camera here that is filming what Pete is looking at and then we've got another camera a tiny camera here this is this camera which is filming Pete's eye and now you can actually see pizza I move like this and you can see these jerky kind of eye movements that's the way that we normally move our eyes so we make a DC Circuit oh I've talked about before like these are movements they're very fast I'm moving to make about three of them per second and what the eye tracker now is doing is trying to work out the center of Pete's eye and this doesn't tell me that much yet so what I need to do now is calibrate this eye rotation to different points in space and I'm gonna do this by by flashing up some dots so let's see whether this is going to work so this is the calibration so Pete if you could just look at that dot for me actually can you come just a little bit closer just look at that so what's happening now is the eye tracker is calibrating spaces in the physical world - Pete's eye rotation and if this works if we normally I would not do this under so much pressure maybe just move your head a little bit towards it do you mind if I just direct your head a little bit that yeah its triggering that that's great so now Pete can you look at me that dot is roughly tracking his eye movements can you see that I was pretty off at the moment because we haven't done the very accurate calibration and what I can do now is I can perform some magic tricks and try and work out where you are looking so thank you very much Pete so I'm gonna remove this from here now of course we don't just do this a lot of this is a lot of fun but we don't just study magic for fun there's a serious side to this so one of the things that we've repeatedly found that all of these studies is that people actually been looking at something and yet they still don't see it so sometimes we have people who are looking at the lighter drop and yet they simply don't see it and again intuitively you think well surely if I'm keeping my eye on something if I'm looking at something I should be able to see this and yet that's simply not the case so there's a lot of instances where you can be looking in the right place but your mind is being misdirected or distracted and that's what influence is whether you're actually going to be able to see something or not and so this has got important practical implications do any of you remember Google glasses yeah Google glasses was this idea that you should be able to present people with information as their riding or riding a bicycle or driving and they should be able to process this information because of course they've got their eyes on the road well what this research is telling us is that this is an awful idea because just because your eyes are on the road doesn't mean that you'll be able to see it think about a mobile phone use so in the UK we banned from driving whilst talking to someone on the handheld set and that's a very good that for a good reason because of course talking to someone on a phone is very distracting and it will prevent you from seeing the cars in front of you but what this research is telling us is that it doesn't matter if your eyes are in the right place it's not because you're just fiddling around with your phone that driving with a phone is dangerous is because your mental capacity is being distracted and that's why talking to someone while stalking driving while stalking someone on the hands-free set is just as dangerous as it is holding a handheld set and yet we don't notice it in fact talking on a phone whilst driving is as dangerous as driving was being legally drunk but at the beginning I said this is all about exploiting these counterintuitive and surprising limitations and for the same reason that magic works it's very difficult to actually convince people to take other measures because you're simply not aware of them so our awareness of the world is far more limited than most of us would assume but what about the things that you do see well I would argue that even if you do see something that doesn't necessarily mean that that's the way the world actually is so have a look at this picture here what do you see who sees a rabbit who's is a duck he sees both switching between okay you're all healthy great this is a form of images known as bi-stable images and it beautifully illustrates the fact that you can actually be looking at something and yet can see something completely different because as your perception changes from a dark to a rapid the outside world isn't changing it's all happening inside your brain and although the eyes are responsible for capturing visual information all of the seeing happens inside our brains and so as you are trying to make sense of the world your brain is using lots of information visual information and trying to figure out what is this thing out here a given that vision involves lots of computations it can be tricked and it can make lead to errors and have a look at these two tables which of these tables looks wider the one on the left or the one on the right or the one on the right looks a lot wider but an actual fact they exactly the same and I can demonstrate this by removing some of the context and rotating the image and you can see now they're exactly the same it's exactly the same surface area yet they look very different I can add the context again and they look very different and even you know even though you know that it's exactly the same surface area you experience it as being very different it's because your brain is trying to interpret what you're actually seeing and what about this you'll remember this picture an image that almost broke the internet because some people see the stripes as black other ceders gold and people couldn't understand how their friends could could experience things differently it's a bit like at one of these big brexit moments that really divided the country because we didn't understand how people could actually look at something as simple as color and expir it in very different ways um now I want to try and resolve that brexit divide by showing an illusion that will hopefully bring it all bring it all together have a look at this cube here got a few squares what what's the color of the square here in the middle orange what about the one pierre brown you all agree on that yeah or a fear of you'd know hopefully most of you will agree on that what if I told you that exactly the same color so this is a beautiful illusion by beau lotto and I can illustrate is once a remove some of the context I'm just doing this by covering some of these squares it looks exactly the same they're the same color once I start removing the context or the masks they look very different and again this is big the reason for this is because even simple things as perceiving color is your brain making stuff up you get some information and then you interpret it in a certain context and here you're using the context of the illumination to try and make the best estimate of what the color actually is are you ready for the biggest or for me like one of the most amazing illusions yeah this is really gonna fry your minds are you ready for this okay I'm going to show you the I'm going to show you the magic trick first and again this is fairly quick gone um this will work much better for you guys than for you guys on the side and for you up there as well how many of you saw a ball disappear somewhere up here yeah quite a few of you great um this is known as the vanishing ball illusion and it's an illusion that was first studied by a guy called norman triplet in about 1900 and the illusion is not as well as the way it's done i just throwed up and then on the final time I just pretend to throw it and I actually see critique Parliament inside my hand but what's interesting is that about 2/3 of people experience a ball moving up and then disappearing somewhere up here so you are seeing something that hasn't actually happened yet but this is that's not even a freaky bit let's get to the really really freaky bit what we do if I told you I could see the future you're laughing how many of you believe me no what if I told you that you can see the future even more surprising what you are and again to understand this we need to have a bit of a look closer look at how visual perception works this is diagram of the visual system and to the brain and again to understand this illusion we need to understand the physiology behind it so as I'm capturing information about the world out here my eyes encode the information the retina has all of these photoreceptors that then transfer transfer that information into electrical signals and that information is then sent three different neural centers to the visual cortex and other cortical areas that are responsible for the seeing so perception happens inside our brains not in the eyes but transmitting that information takes time it takes about a tenth of a second or hundred milliseconds for the information to travel from the eye to the visual cortex a tenth of a second so what does that mean well of course it means that by the time you've seen something it's already in the past and yet catch mating amazing can you catch it to me you can applaud me because and I'm not being sarcastic because of course this should simply be impossible if I'm seeing the world in the past how can you catch something then you might think okay a tenth of a second is not that long it's a for a second if I'm walking at about this is about a 1 meter per second a tenth of a second delay means that the world should be lagging about 10 centimeters behind me and yet it doesn't I'm not constantly bumping into things I can catch things so how can I do this well the reason we can do this is because you are genuinely seeing the future so what your brain is doing is every second of your daily life it's actually using information from the past to predict what the future is going to be so what you're seeing us there now is not there now but it's what your prey predicts turn out to be based on information from the past isn't that amazing I mean it fries my mind and I've talked about and studied this for many years and so the reason why this vanishing ball illusion works is because what you're seeing is based on what you're predicting so when that ball is moving up it's your brain predicting that it should be moving up based on everything that you are expecting and it's again one of these beautiful examples of how we can use magic to try and uncover some of these secrets I know a lot of you this is not a feel-good it's not not really a feel-good talk but I'd like to end up on a kind of like a better message because so far just illustrated how rubbish you are all of these things but that's the wrong way to think about the brain let's have a look at mobile phones throughout the years engineers have managed to pack more more processing capacity into smaller and smaller devices and of course processing information in their brain requires neural and these neurons require energy and then you require a place to be housed and so there's a simple conundrum really either we process all of the information completely accurately but that would require these huge brains I mean the size i've got on my back head would have to grow this big so my body would form barely barely be able to support it or we come up with very clever tricks and shortcuts to facilitate some of this information processing and luckily for us this is the route that evolution has taken us down so although your brain is constantly being fooled by a lot of these illusions well this is something that we should celebrate because what it illustrates is just how clever the brain is are solving these truly impossible tasks so thank you very much for your attention I have just recently published a book called experiencing the impossible which is Gogh which has a lot of these readers discusses a lot of these surprising illusions I hope you found this illuminating and interesting thank you very much ok so we have a time for a couple of questions and thank you fascinating talk thank you hey why do we you say it's about conflict and yet we delight in it why do we find it such fun to have our to be so confused that's a really interesting question and then what's even more interesting about it is that I think is oh it's a quite even magic is such an old art form and yet it's a question that very few have ever post and I think there's different reasons for this for one if we look at infants for example infants are really drawn towards things they don't understand and we actually uses in the lab so to try and understand how infants process information we give them different types of delusions and what you find is that the spend more time looking at the illusion that doesn't make sense that they're more the one that violates their understanding of the world and that makes evolutionary sense because if you try and explore things that don't actually make sense well that encourages you to learn more about the world and it's possible that one of the reasons why we enjoy magic is because of this deep-rooted cognitive mechanisms mechanism that encourages us to to explore the world but this of course there's another side as well as the whole idea of deception as well why is it that people enjoy deception I mean I'm lying to you I'm deceiving some of this may seem quite unsettling as well and I think in everyday life some of these illusions and these deceptions they could feel really unsettling but in the context of a magic performance you know this is a safe space you know this is a performance and that allows you to embrace some of these and negative emotions it's a bit like with horror films as well a lot of people enjoy horror films and they enjoyed them because they can watch them in a safe space whilst if you'd be walking down the street and you see someone being shot or mutual aid mutilated that wouldn't be a very nice experience and I think so I think there's lots of different psychological reasons why we enjoy magic but what I find really interesting is that nobody's actually answer to ask these questions we've asked questions about why we enjoy arts while I'm enjoying music dance and yet the simple question why do we enjoy magic is one of these questions that we really only just now started to understand thank you and we have a question you might be able thank you I think you said that not everyone would have seen that ball going up the last time when it didn't go up what does that say about those of us who didn't see it go up we simply don't know yet we have carried out quite a few experiments on this we carried out a study on autism I'm not going to go into the results in too much either because they're actually very difficult to interpret but of course there's different reasons I mean maybe maybe you're just not making those predictions maybe you're paying less attention and at the moment we simply don't know I mean yeah I could I could go into really complicated explanation with regards to autism but I just don't think we've got the scope really to go into that much detail here I've written about it in more detail in my book as well if you're ready okay thank you very much we have run out of time but I will say if you do have any burning questions we do have an event in books that you can send them to us and then we will pass them on to speakers and hopefully if they have time because they are very busy people and we might get some of them answered and but I'm very aware it is tea break time but before you do that and toyotas on the ground floor if you need those and a huge round of applause and thank you for good to say [Applause]

Channel: The Royal Institution

Views: 28,480

Rating: 4.8619046 out of 5

Keywords: Ri, Royal Institution, magic, science of magic, psychology, neuroscience, gustav kuhn, experiencing the impossible, optical illusion, magic tricks, lecture

Id: 4pxYVlgSzCg

Length: 43min 48sec (2628 seconds)

Published: Wed Nov 06 2019

Reddit Comments

[u/sakujosakujosakujo]

I was pleasantly surprised to see that guy on this year's New Scientist Live event. There is nothing more awe-worthy than seeing science and magic in one room united for the single purpose of education & entertainment.

[u/djeclipz]

So happy to see the SoM taking off! Gustav is a great guy and his book is fantastic.