Dr. David Eagleman, Neuroscientist -- The UP Experience

and so it's our honor to again welcome back our first presenter in MC this morning dr. David Eagleman from Baylor College of Medicine he's been with us for four years he's a New York Times bestselling author both both fiction and nonfiction as well as a Guggenheim Fellow and I like to welcome to the stage dr. David Eagleman thanks okay by a show of hands how many of you have ever had a life-threatening experience where you thought you might die okay how many of you in that during in that experience felt like time ran really slowly like it took a very long time to happen okay well that's what happened to me when I was eight years old I fell from the roof of the house under construction and it felt like it took a really long time it took so long that on the way down I was thinking about Alice in Wonderland and how this must have been what it was like for her to fall down the rabbit hole I had very clear thoughts it seemed to last a long time when I got a little bit older and I went to high school physics I learned the equations and I did the calculation and I found that the fall from the roof to the floor took me just a fraction of a second and that got me very interested because I thought how could my brain have thought so many clear thoughts during that time why did it seem like it took so long so when I grew up I became a neuroscientist and I've devoted a large part of my career to trying to figure out how the brain constructs time and how we push everything through this filter of our reality so time is so interesting because it's the most common noun in the English language and it's one of the most important things in our lives we worry about how we spend it on days like today we invest our time we try to save time we covet time it's it's one of the most important elements in our life and yet it is one of the least understood because you can't touch it or taste it or feel it or smell it and there are all these questions that we have about time like why does time seem to slow down when you're in a life-threatening situation and why does time speed up as we get older so what I want to tell you about today is my journey through studying time and some of the surprises that I've come up with along the way so to study something as big as time it helps to zoom in on very simple aspects of it and one of the first things that I started doing was studying a very simple illusion called the flash lag illusion so if you have a moving object let's say the green ring and I'm gonna flash something right in the middle of the Ring it'll looked to you like the flash is not right in the middle so look at the red dot and as the ring moves around what you might be able to see is that even though the flash is right in the middle of the Ring it looks like the ring is slightly ahead of the flash does everyone see that so what it actually looks like is even though reality that's hitting your eye is that the flash is right in the middle of the ring what it looks like to you is that the ring is ahead of the flash and the question is why this is a very simple illusion that opens up a deep inroad into how our brains understand and construct time and what had been understood in the literature was that maybe what's happening here is that your brain is collecting up information and then at the time of the flash your brain guesses ahead about what's happening in the near future so I wanted to test whether that was true or not and I did something very simple some years ago which is I had a ring come around and a flash happens in the middle just like you saw but immediately after the flash one of three things happens at random either the ring keeps going like you just saw or the ring reverses direction right after the flash or the ring comes to a stop right after the flash so the key thing to note here is that everything up to and including the flash is identical and the only thing I'm changing is what happens in the future of the flash so if the brain is guessing ahead you should get the same result in all three conditions but here's what it actually looks like I'm going to show you all three cases fat there's continuous there's reversed and they're stopped do that once more continuous reverse and stopped now what you might be able to see is that in the continuous case it looked like the ring was below in the reverse case it looked like the ring was above and in the stop case there was no illusion now why is that such a weird result it's because I'm asking subjects what they see at the moment of the flash but their answer depends on what happens just in the future of the flash so in other words our perception of what happens at some moment in time actually incorporates a little bit of future into it it's very weird right what it means is the brain is not guessing ahead like that instead it's more like the brain is collecting up a lot of information after an event and retrospectively saying what it thinks it saw at the time of the event now there's nothing backwards happening in time here the right way to do this is with two timelines so you've got time in the outside world and some event happens and then you've got time in your head and when an event happens in the outside world it takes time for that to get registered by you consciously and what this very simple illusion is able to show is that there's some information after the event that gets incorporated into what you think you see at the time of the event so surprise number one is that you live in the past and I don't mean like this or like this I mean that I mean that when you think the moment now occurs it's already happened because it takes time for the brain to stitch together the information put it all together figure out what's going on and serve up a story to your conscious mind and it's already over by that time and what this means is that your conscious awareness is like one of these live television shows which is not actually live these shows are aired with a little bit of a delay in case somebody cusses or falls down and so if they're not live and it's the same with your perception you're you're seeing the past for all you know I'm already done with this talk okay well the question is how far in the past are we well with the experiments that I was able to do in the visual system what I found is that it's a out a tenth of a second that gets incorporated after an event and subsumed into what you believe you see at the time of the event and and the amount that we live in the past is at least that long it's at least a tenth of a second plus all sorts of signal travel time around the brain but what's interesting is this is just for the visual system and it struck me at some point that if your brain really wants a unified perception of everything that's going on it needs to collect all the senses it needs to gather all the information from the whole body to put together a unified story of what's happening in time and for that it would have to wait for the slowest signals to arrive and those are the signals from your toes because the signals from your toes have to climb all the way up your legs and up your spinal cord to arrive at the brain and it's got to wait for that and that led me to a a bizarre but testable prediction which is that tall people live farther in the past than short people and what's interesting is I announced this once on on NPR I mention this and I got about a hundred emails from people who said I'm short and I really appreciate you saying that so I was the hero short people for a day um so here's the question though the question is if the brain needs to collect up all this information from the different senses from vision and hearing and from touch and so on how does it coordinate all these how does it how does it figure out how to put together all these signals in such a way that it can tell what's happening in the outside world and in order to explain this I'm gonna step back eight centuries and tell you about Kublai Khan who was the Mongol Emperor who by the time he was a young man controlled the largest empire that the world had ever known essentially his empire contained 1/5 of the entire inhabited landmass in the world so Kublai Khan positioned himself in what's modern-day Beijing and the thing to note here is that these were the days before trains and cell phones and internet he had no way of knowing his own empire because it was too vast there's no way that he could could explore this whole thing so what Kubla Khan did is he would hire emissaries like Marco Polo and they would go and and travel out across his empire and convey news back to him about what his empire contained and of course he had many different emissaries and they would all come back to him and this is how he got to know his world now I've never heard a historian mention this book but what I imagine must be true is that the Great Khan had a time problem which is that different emissaries would travel at different rates based on wars or weather or things like Dada different travel conditions and so it must be that the messages were getting delivered to him at all sorts of different times so you can imagine a situation where someone comes to him and says hey a war just ended and then someone else comes to him and says hey a war has just begun and it's the same war they're talking about and his job is to figure out the actual order of things in his empire this is exactly the same problem that the brain has the brain sends out signals and then it gets signals back along all sorts of different routes touch and hearing and seeing it's getting all these signals back and its job is to figure out what actually happened out there and the challenge for the brain is the same as it is for the Great Khan which is that signals arrive in the brain at different places at different times these things are processed at very different speeds but here's the mystery somehow even though the signals arriving at very different speeds your conscious awareness of the world synchronizes this so to the soccer player he's hearing it and seeing and feeling it all at the same time if I clap my hands you see it and hear it and I feel it all at the same time as though it simultaneous well what that means is that the brain is having to pull off lots of real video editing tricks it's really going through a lot of trouble to take bubble hitting that just figuring out causality which is to say if I get to take the tour and learn from it versus things happen in the world and then I sent out an act in which case the brain doesn't learn on that at bottom causality is a temporal order judgment you have to get straight did I do something and then I got the sensory feedback or did it happen the other way you have to get that straight in order to make this judgment the challenge to the brain is that not only do these signals come in at very different speeds but these speeds change so for example when you grow from an infant to an adult it takes longer to send signals out and get those signals back or even on a faster timescale when you walk from the bright outdoors into a dim room that changes the speed at which your eyes are talking to the rest of your visual system that slows down this is why by the way if you're ever playing volleyball as the Sun Goes Down or something everybody starts missing the ball and it hits them in the face and so on because the speed at which their eyes are talking to their brain changes okay so somehow the brain has to figure out how to adjust on the fly all the time it's expectations of how long these things take and so I reasoned that maybe the best way for the brain to figure out this problem and solve it is by interacting with the world so every time you you interact with the world and you touch things and you kick things and you hit things what you're doing is you're saying alright I'm putting out some motor action and I want everyone to synchronize their watches because the best way to predict the future is to create it so when I do that I know that I should hear it and feel it and see it all at the same time and if I don't then my brain can adjust that so that line of reasoning led us to a very simple experiment which is the following we had people come in the lab and press a button and when they would hit the button a flash of light would happen so every time they hit the button the flash of light would happen it was clear that they were causing it now what we did is we very sneaky leave inserted a small delay about a tenth of a second and people hardly even noticed this if they notice it at all but now when they hit the button there's a little delay before the flash of light happens because they're the ones causing it their brain starts to adjust the perceived timing and they start to believe that these things are closer together and one of the ways we can test that is the following what we do is after they've gotten used to this delay we now remove the delay so now they hit the button and the flash happens right away and what they think is that the flash happened before they press the button so they press it a flash happens they say oh that wasn't me I didn't do that and that got me very interested because I thought I've seen that sort of thing somewhere before where people have credit misattribution and I thought the place where I've seen that before is with schizophrenia and that got me wondering if there are pathologies of time where if you have these very sophisticated editing systems that go awry what would happen exactly and that led me to this hypothesis that we've been pursuing in my lab for a few years now that fundamentally at bottom schizophrenia might be a disorder of time perception in the following sense if you're not getting the order of things right in the world reading things and saying oh that wasn't me I didn't do it you're going to have a very fragmented cognition you need to get time right at bottom for everything else to make sense and just to give you one example of how this works consider the fact that you're always talking to yourself you're always generating an internal voice and listening to it imagine now if you got the temporal order wrong just by a few milliseconds you'd have to attribute that voice to somebody else and so there are many aspects in which if you're getting timing wrong you're gonna have other sorts of cognitive problems and that's one of the things that we're pursuing in the lab right now okay now I'm gonna return to the question that I started with which is can subjective time actually run in slow motion there's so many of us that have had this sort of experience where we feel like things took a very long time when our life was in danger and because I was trying to figure out how the brain constructs time I needed to understand if this was actually true or what the what the issues were here and as you can imagine there was nothing in the literature on this because you can't easily stick people in a situation like this so I thought look there are two hypotheses here the first one is that during an accident you're actually seeing the world in slow motion like neo in the matrix you actually have a higher time density and the other hypothesis is that somehow the way memories are laid down during the event when you look back on that you think wow that must've taken a really long time so I thought how can i distinguish these two hypotheses so with a couple of my students we made the following we built a device that flashes numbers at you in a certain way that we can ask you to report these numbers and we can measure the speed at which you're taking in the world because it turns out if we alternate these images quickly for some random number you're able to report the number with no problem but if we alternate them just a little bit faster then you can't see it at all and so what we can do is find exactly the speed at which we can yeah at which you can see the world and then we can put random numbers on and strap this thing to your wrist and we can find out if you're in a terrifying situation can you actually read the device and a faster rate than you would be able to normally in other words can you see in slow motion so we built the device now the question is alright how do we make them scared so so the first idea we had was okay let's stick volunteer subjects in a life-threatening terrifying situation but because we're scientists we always try to come up with a better idea actually we never did get a better idea so we stuck with the first idea and we drop people from 150 foot tall tower in freefall and we measured their time perception on the way down so so here's what this looks like this is a subject we drop 23 subjects and they're falling this is what it's like when you're falling it's very high and you're caught in a net below so it's a it's a short experiment we had to do this up in Dallas because it's actually illegal here in Houston and it took me seven months to get this approved by the Ethics Board but we finally did okay so there's two there's two parts to the experiment part one is I had people with a stopwatch I had them watch someone else's fall and then retrospectively they estimate how long they thought that fall took then part two was I had them after their own fall used the stopwatch to estimate how long their own fault took in other words to remember themselves falling and what happens when they're thinking about their own fall they estimated to be at least 36 percent longer so in other words we were able to replicate this duration distortion people thought it was much longer when they're thinking about their but the real question is can they actually see in slow motion like neo and the answer is no it turned out that the speed at which people could take things in was exactly the same when they were flying as when we measured them in ground-based control experiments so that was a very interesting discovery to us it seems like a paradox right how could it seem like time has stretched out and yet you're not seeing anything in slow motion and this is what led us to really understand that time and memory are intertwine when you're in a life-threatening situation there are other parts of your brain especially a nucleus called the amygdala which kicks into gear when you're it's essentially your emergency control center that comes online and it lays down memories on a secondary memory track and these memories are dense and what happens is when you're at the end of the event you look back you remember all sorts of details that normally you forget and so when you look back you have so much footage to draw from I remember this I remember that detail I remember that detail and it seems to have lasted longer in other words the way we estimate duration has a lot to do with how much memory we've laid down how much footage we have to draw from and this simple fact ly led me to understand something which is which is why does time speed up as you grow older well it's because when you're a kid you're trying to figure out the rules of the world and everything is novel to you and you're you're riding a bike and you're trying out for the baseball team and you're falling off a roof you're doing all kinds of things and you're writing down all these memories and when you get to the end of a childhood summer and you look back you have so many novel things as you get older you've figured out the rules of the world which is advantageous for operating in the world but things aren't that novel to you anymore you've sort of seen all the patterns before and as a result when you get to the end of an adult summer and you look back there's just not that much new there's not that much footage to draw from and as a result the whole thing seems to have moved very quickly and so because I'm a biologist maybe you were hoping that I'd tell you how to live longer but instead what I can tell you is how to make it seem as though you've live longer and that is to seek novelty and so we're gonna start this right now so anyone who's wearing a watch in the audience I'd like you to take your watch off and transfer it to the other hand right what you're gonna do is shake up your neural circuits so that things are new to you and this helps to keep the brain active and to lay down new memories what I want you to do is drive home a different route from work every day because otherwise you've probably noticed that your drive to and from work shrinks to zero time right you don't even lay down any memories of that anymore and therefore it seems to take no time at all drive a different way home when you get home tonight completely rearrange your desk in your office space and the main thing to do which you guys are already doing a great job of is make sure that you stretch your mental landscape by putting yourself in situations where you are learning something new so the last surprise that we learn about time is if you slow it down seek novelty thank you so much for your attention here's the clicker you just you just gave everybody a lot of footage for not just today but for quite a bit let me ask a quick question yes you wrote an article on the title of which was will I perceive the event that kills me can you elaborate on that just a little bit yes yes so this is an article I wrote called will you perceive the event that kills you and the question I was asking is given the fact that we live in the past that it takes time for our brain to construct footage of what's happened it struck me that if suddenly you've got an unexpected bullet to the brain or a bomb went off or something like that that your brain would be gone before it has time to construct the story of what just happened I know this is morbid but but it it turns out by the way did anyone see the final episode of The Sopranos anyone see the finale okay the finale after eight years is Tony Soprano sitting in the diner and he's looking he's talking with his family and then all of a sudden the footage ends and the interpretation I think the director what he wanted to do was show that Tony caught a bullet to the back of the head and in fact it had been priests aged in an earlier season this issue of will you even see it coming in other words if you if your brain disappears before it has time to construct the conscious story then your experience would be that the footage just ends so how's that for an up experience okay I'm gonna let you take it from here great okay you

Channel: FORA.tv

Views: 9,494

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Keywords: science, psychology, social science, anthropology, neuroscience, cognitive, cognition, brain, mind, perception, UP Experience, David Eagleman, author, thought leaders, creators, innovators, technology, trends, ideas, global movements, creativity, presentation, future

Id: L_ulCRdLUzo

Length: 23min 26sec (1406 seconds)

Published: Thu Jan 24 2013