WEBVTT - Ep100 "Why do brains love slow motion video?" 0:00:05.160 --> 0:00:08.160 Why do we love to watch slow motion in the movies? 0:00:08.720 --> 0:00:13.080 What do Bonnie and Clyde or Inception or the Matrix 0:00:13.280 --> 0:00:17.280 tell us about brains and time perception? And what does 0:00:17.280 --> 0:00:20.480 any of this have to do with unmasking hidden data 0:00:21.040 --> 0:00:26.560 or champion bicyclists or elementary particles or murderers or HG 0:00:26.640 --> 0:00:32.839 Well's time machine. Welcome to Intercosmos with me David Eagleman. 0:00:33.159 --> 0:00:36.040 I'm a neuroscientist and an author at Stanford and in 0:00:36.080 --> 0:00:39.640 these episodes we dive deeply into our three pound universe 0:00:40.120 --> 0:00:44.760 to understand some of the most surprising aspects of our lives. 0:00:54.680 --> 0:00:58.720 Today's episode is about slow motion and what's going on 0:00:58.760 --> 0:01:01.400 in the brain and why we are attracted to it. 0:01:02.000 --> 0:01:03.520 So we all know that if you go to any 0:01:03.960 --> 0:01:07.560 random blockbuster, you're really likely to see some of the 0:01:07.600 --> 0:01:14.280 sequences in slow motions gets employed to accentuate the choreography 0:01:14.360 --> 0:01:17.560 of gun battles or sword fights, and of course it 0:01:17.560 --> 0:01:19.480 doesn't even have to be fighting. You might see it 0:01:19.520 --> 0:01:24.280 in a shot of a basketball dunk, or a flipping car, 0:01:24.720 --> 0:01:28.600 or sprinters crossing the finish line, whatever the shot. What 0:01:28.720 --> 0:01:33.760 we get to witness is fluidity and elegance in a 0:01:34.400 --> 0:01:39.920 visually captivating spectacle that has become a hallmark of Hollywood, 0:01:40.160 --> 0:01:43.319 and it goes even beyond action movies. Even in dramas 0:01:43.400 --> 0:01:48.520 and romances. We see slow motion get leveraged to capture 0:01:48.920 --> 0:01:54.440 intimate emotional moments. We savor the subtleties of someone's eye 0:01:54.480 --> 0:01:59.720 movements or facial expressions or body movements. We understand something 0:01:59.760 --> 0:02:05.240 about the unspoken longing and restrained passion between two protagonists, 0:02:05.440 --> 0:02:09.240 or we watch a tear fall, or we see the 0:02:09.360 --> 0:02:12.800 moment that someone has an unexpected revelation. 0:02:13.400 --> 0:02:15.120 So we see slow motion all the time. 0:02:15.160 --> 0:02:19.120 But have you ever wondered from a neuroscience perspective what 0:02:19.280 --> 0:02:23.720 that's all about and why brains love it so much? Yeah, 0:02:23.840 --> 0:02:28.560 me too, and hence today's podcast. So let's start by 0:02:28.639 --> 0:02:33.639 zooming way out. When did slow motion really start in movies? 0:02:34.240 --> 0:02:36.440 You may be surprised to know that the era of 0:02:36.560 --> 0:02:41.120 slow mo didn't really begin until nineteen sixty seven. And 0:02:41.200 --> 0:02:43.919 what stuns me about this is that by nineteen sixty 0:02:43.960 --> 0:02:49.119 seven we already had supersonic flight and bionic limbs and 0:02:49.240 --> 0:02:53.160 credit cards and digital music, and the space race was 0:02:53.200 --> 0:02:58.840 in full swing, but nobody was using slow motion until. 0:02:59.240 --> 0:03:02.560 I thought, I have an idea about the end that 0:03:02.680 --> 0:03:09.160 should be like a spastic ballet, and that was the image. 0:03:09.480 --> 0:03:12.720 That's Arthur Penn, the director of the nineteen sixty seven 0:03:12.840 --> 0:03:16.799 film Bonnie and Clyde. This was a big Hollywood blockbuster 0:03:16.919 --> 0:03:21.360 that dramatized the real life crime spree of Bonnie Parker 0:03:21.400 --> 0:03:24.840 and Clyde Barrow, and the stars were Fade, Done Away 0:03:25.000 --> 0:03:27.680 and Warren Batty. So Bonnie and Clyde were a young 0:03:27.760 --> 0:03:32.000 couple who became bank robbers during the Great Depression, and 0:03:32.040 --> 0:03:35.119 in the movie, they travel across the country with their 0:03:35.360 --> 0:03:40.000 growing gang and their crimes escalate, and this attracts the 0:03:40.080 --> 0:03:47.040 relentless pursuit by law enforcement, which culminates in a violent ambush. 0:03:47.440 --> 0:03:51.200 And then so I came to the technicians and I said, look, 0:03:51.240 --> 0:03:52.320 this is what I want to get. 0:03:52.400 --> 0:03:53.600 They said, you can't do that. 0:03:54.600 --> 0:03:58.160 I said, I want four cameras. I want them running 0:03:58.160 --> 0:04:04.400 at different speeds, I want them ganged together, and I 0:04:04.480 --> 0:04:07.080 want to roll them all at the same time. 0:04:07.680 --> 0:04:11.080 And so that's what happened. In the final scene, the 0:04:11.160 --> 0:04:17.920 cinematography decelerates into a balletic slow motion as Bonnie and 0:04:17.960 --> 0:04:24.160 Clyde meet their bloody end. Under a hailstorm of police bullets, 0:04:24.839 --> 0:04:28.440 so as they experience their final moment, the audience is 0:04:28.640 --> 0:04:34.839 given some extra seconds to be witnessed to it. Now, 0:04:34.839 --> 0:04:38.440 this really shocked a lot of people. Critics called Arthur 0:04:38.480 --> 0:04:43.560 Penn's slowed down death scene gratuitous and callous, but. 0:04:44.279 --> 0:04:45.520 The idea caught on. 0:04:46.200 --> 0:04:49.320 Bonnie and Clyde had opened the door to slow motion 0:04:49.760 --> 0:04:51.599 and it's never been shut since. 0:04:52.040 --> 0:04:52.240 Now. 0:04:52.279 --> 0:04:55.120 By the way, it's not that the technology was new. 0:04:55.320 --> 0:04:59.040 The method for slow motion movies came into being in 0:04:59.160 --> 0:05:03.440 nineteen o five four when the Austrian physicist August Musker 0:05:03.680 --> 0:05:07.599 invented the technique. So what's the technique. You just speed 0:05:07.720 --> 0:05:12.160 up the recording camera so you're capturing more frames per second. 0:05:12.360 --> 0:05:16.240 In this way, what you're doing is capturing faster changes. 0:05:16.320 --> 0:05:19.839 The time in between each picture is shorter than normal. 0:05:20.440 --> 0:05:24.120 So then when you play the film strip back at 0:05:24.240 --> 0:05:28.240 regular speed, like twenty four frames per second, then the 0:05:28.279 --> 0:05:32.240 scene appears to be in slow motion because the change 0:05:32.520 --> 0:05:35.919 from one frame to the next is very small. This 0:05:36.080 --> 0:05:39.520 was initially just getting used for scientific purposes to slow 0:05:39.600 --> 0:05:43.240 down processes that you can't see well with the naked eye, 0:05:43.400 --> 0:05:47.520 but eventually slow motion was adopted by filmmakers to enhance 0:05:47.839 --> 0:05:51.120 visual storytelling. Now, before we go on, I want to 0:05:51.120 --> 0:05:54.840 make sure we have a clear distinction between slow motion 0:05:55.000 --> 0:05:58.440 in movies and the impression that you might have if 0:05:58.480 --> 0:06:02.760 you have experienced a life threatening situation and it feels 0:06:03.200 --> 0:06:07.520 like the event took a long time. Is this because 0:06:07.600 --> 0:06:10.480 the frame rate of your brain changes. 0:06:11.279 --> 0:06:11.400 No. 0:06:12.320 --> 0:06:15.719 Ninety nine episodes ago, I talked about the impression we 0:06:15.800 --> 0:06:19.920 have of very frightening events having taken a long time. 0:06:20.240 --> 0:06:22.840 This is something I first experienced as a child when 0:06:22.880 --> 0:06:26.320 I fell off of a roof. I have very clear memories, 0:06:26.320 --> 0:06:29.640 and it feels like the whole thing took a few seconds, 0:06:29.920 --> 0:06:32.599 even though I can calculate that it only took point 0:06:32.680 --> 0:06:35.640 six seconds to get from the top to the bottom. Now, 0:06:35.640 --> 0:06:40.200 it turns out that this observation about scary events seeming 0:06:40.240 --> 0:06:42.600 to last longer. This is at least one hundred years 0:06:42.640 --> 0:06:45.880 old in the scientific literature, although I imagine that people have 0:06:46.040 --> 0:06:49.920 noticed this from time immemorial. But my laboratory was the 0:06:49.960 --> 0:06:52.560 first to run experiments on it to see if it 0:06:52.600 --> 0:06:57.520 was an issue of a faster perceptual frame rate, which 0:06:57.560 --> 0:07:02.480 again is how a movie camera captured slow motion or instead, 0:07:03.160 --> 0:07:06.440 does it happen to us? Because of the laying down 0:07:06.520 --> 0:07:11.760 of denser memories and the retrospective estimate of how much 0:07:11.880 --> 0:07:16.640 time had passed. We ran experiments by presenting information at 0:07:16.680 --> 0:07:20.400 a faster rate than a person could normally see, and 0:07:20.440 --> 0:07:23.000 then we put them in a very scary situation where 0:07:23.000 --> 0:07:25.720 we dropped them from one hundred and fifty foot tall 0:07:25.800 --> 0:07:28.800 tower and they were caught in a net below. If 0:07:28.840 --> 0:07:33.200 a person is like a camera speeding up its frame rate, 0:07:33.560 --> 0:07:36.160 then they would be able to easily see the information 0:07:36.280 --> 0:07:39.920 we were flashing at them. But our results indicated that 0:07:39.960 --> 0:07:42.320 the slow motion effect was a. 0:07:42.360 --> 0:07:43.760 Trick of memory. 0:07:43.880 --> 0:07:46.640 In other words, when you're in fear for your life, 0:07:47.040 --> 0:07:51.920 your brain writes down dense memory. It's capturing everything it can, 0:07:52.400 --> 0:07:55.680 whereas normally your memory is very leaky. So when your 0:07:55.680 --> 0:07:59.400 brain then asks what just happened? What just happened and 0:07:59.560 --> 0:08:03.520 reads it out all those dense memories, it estimates that 0:08:03.600 --> 0:08:08.000 the event must have taken longer. Your brain has all 0:08:08.040 --> 0:08:11.960 these rich memories, let's say, the hood crumpling and the 0:08:12.000 --> 0:08:15.080 rear view mirror falling off, and the expression on the 0:08:15.120 --> 0:08:19.280 other driver's face and so on, And given that opulence 0:08:19.320 --> 0:08:23.200 of memory, your brain calculates that the whole event must 0:08:23.200 --> 0:08:27.800 have represented a slightly longer duration. In other words, what 0:08:28.000 --> 0:08:32.040 happens during a scary event is a totally different mechanism 0:08:32.520 --> 0:08:36.040 than slow motion video. Now, when I published our findings, 0:08:36.080 --> 0:08:37.839 some people said to me, Hey, I don't think your 0:08:37.840 --> 0:08:41.760 conclusion is correct because I had a life threatening car 0:08:41.800 --> 0:08:45.360 accident and I know what I experienced. So I said 0:08:45.400 --> 0:08:48.680 to them, Okay, but the guy in your passenger seat 0:08:48.720 --> 0:08:52.160 who was yelling watch out, did it actually. 0:08:51.800 --> 0:08:53.320 Sound like he was saying. 0:08:57.240 --> 0:09:02.040 Because if not, that means that time is not actually dilated. 0:09:02.440 --> 0:09:06.760 Because if you are recording something with a faster frame rate, 0:09:07.080 --> 0:09:11.319 then when you play it back out, everything is stretched. 0:09:11.559 --> 0:09:15.079 So with your experience of time dilation, it's not an 0:09:15.120 --> 0:09:17.640 issue a faster frame rate like a movie camera, but 0:09:17.679 --> 0:09:22.760 instead of denser memory. Please listen to episode one of 0:09:22.800 --> 0:09:25.640 this podcast for much more about that. And the reason 0:09:25.640 --> 0:09:27.840 I'm telling you about this now is because we're going 0:09:27.880 --> 0:09:31.840 to return to this in a few minutes. For now, 0:09:32.200 --> 0:09:36.199 let's get back to filmmaking, where the mechanism is very straightforward. 0:09:36.240 --> 0:09:39.760 You just take more frames per second. Now, I said 0:09:39.840 --> 0:09:42.360 that Bonnie and Clyde was the first major movie to 0:09:42.559 --> 0:09:45.600 use slow motion, but there were actually experiments with it 0:09:45.679 --> 0:09:49.720 before that. One of the earliest uses in cinema was 0:09:49.760 --> 0:09:54.600 in an epic silent film called Intolerance in nineteen sixteen. 0:09:55.160 --> 0:09:58.199 This was made by a director named D. W. Griffith, 0:09:58.200 --> 0:10:01.920 who was experimenting with all millions of techniques of filmmaking 0:10:02.400 --> 0:10:05.920 and used slow motion just a little bit to accentuate 0:10:06.400 --> 0:10:11.319 dramatic moments and heighten emotional tension. But two World Wars 0:10:11.320 --> 0:10:14.480 that over half a century passed before I was used 0:10:14.480 --> 0:10:18.000 in Bonnie and Clyde, in part because the technology had 0:10:18.040 --> 0:10:21.880 to advance to make slow motion more accessible and versatile. 0:10:22.120 --> 0:10:25.520 By the nineteen sixties, people were building high speed cameras 0:10:25.720 --> 0:10:29.040 which were capable of capturing hundreds of frames per second 0:10:29.120 --> 0:10:33.520 and eventually thousands, and this is what allowed filmmakers to 0:10:33.640 --> 0:10:38.679 push new boundaries of representing time and creating effects that 0:10:38.760 --> 0:10:43.200 audiences were captivated by. And the nineteen sixty nine film 0:10:43.360 --> 0:10:46.400 The Wild Bunch, two years after Bonnie and Clyde, really 0:10:46.440 --> 0:10:49.840 helped popularize the technique. And now, of course we don't 0:10:49.840 --> 0:10:53.040 even think about it much because it's a staple of 0:10:53.120 --> 0:10:57.200 modern filmmaking. For example, I recently watched a movie called Wanted, 0:10:57.240 --> 0:11:00.840 which uses super slow motion every time there's a gun battle. 0:11:01.160 --> 0:11:05.680 Where you may remember Christopher Nolan's movie Inception, which has 0:11:05.760 --> 0:11:11.120 these beautiful slow motion dream sequences, especially in the kick 0:11:11.200 --> 0:11:15.400 moments where they're transitioning from one reality to another. So 0:11:15.880 --> 0:11:20.280 increasingly since nineteen sixty seven, movies use time warping all 0:11:20.320 --> 0:11:23.600 the time, and the success of this approach has overtaken 0:11:23.960 --> 0:11:27.320 commercials and music videos, and it's a standard tool on 0:11:27.360 --> 0:11:30.439 our cell phones. And in fact, you can tell when 0:11:30.480 --> 0:11:33.640 something has become a staple because then it shifts into 0:11:33.679 --> 0:11:37.440 the focus of the comedians. Some years ago, the comedian 0:11:37.559 --> 0:11:40.240 Dave Chappelle did a skit in which he was proving 0:11:40.360 --> 0:11:44.720 that everything quote looks cooler in slow motion. So in 0:11:44.760 --> 0:11:48.319 the skit, he walks into the laundromat and says hello 0:11:48.360 --> 0:11:51.520 to a kindly middle aged woman who is preparing her laundry, 0:11:51.960 --> 0:11:54.320 and she takes off her sweatshirt so she can add 0:11:54.360 --> 0:11:58.080 it to her hamper, and it's all very innocent and laundromaty, 0:11:58.440 --> 0:12:02.600 and then he says, let's replay this video in slow motion, 0:12:03.240 --> 0:12:07.600 and now everything changes from mundane to sexy in the 0:12:07.800 --> 0:12:11.040 slow motion replay. The woman lifts the sweatshirt over her 0:12:11.080 --> 0:12:14.640 head and is suddenly replaced by a beautiful young model 0:12:14.679 --> 0:12:19.040 who tosses her hair in a vigorous breeze, and she 0:12:19.160 --> 0:12:22.040 and Dave Chappelle start dancing around each other as the 0:12:22.080 --> 0:12:25.840 wind blows. So this skit cracked up the audience. But 0:12:25.960 --> 0:12:30.480 this just underscores our question, what is the appeal of 0:12:30.520 --> 0:12:34.440 slow motion? Why do we find it so attractive? I 0:12:34.559 --> 0:12:40.120 propose four reasons. The first is the increased esthetic appeal. 0:12:40.160 --> 0:12:44.440 When you decelerate time, you can experience so many more 0:12:44.600 --> 0:12:47.920 details of this scene. And just like Dave Chappelle noticed, 0:12:48.000 --> 0:12:53.480 even ordinary moments get turned into extraordinary visual spectacles. And 0:12:53.520 --> 0:12:57.200 this is because by slowing down time, you highlight the 0:12:57.280 --> 0:13:01.160 intricate features of a scene. The human eye is naturally 0:13:01.200 --> 0:13:05.559 attracted to detail, and slow motion allows us to appreciate 0:13:05.600 --> 0:13:10.160 the subtle nuances of a character's movement, or the play 0:13:10.200 --> 0:13:14.199 of light and shadow, or birds exploding out of a tree, 0:13:15.120 --> 0:13:18.280 or the look on someone's face as they turned to 0:13:18.360 --> 0:13:22.040 see that their lover has left. So you remember the 0:13:22.040 --> 0:13:24.800 Matrix which came out in ninety nine, and you certainly 0:13:24.840 --> 0:13:29.400 remember this bullet dodging scene where Neo bends backward to 0:13:29.520 --> 0:13:33.760 avoid a series of bullets fired at him, and this beautiful, 0:13:34.000 --> 0:13:40.480 slow sweeping shot captures the fluidity in the wondrous precision 0:13:40.520 --> 0:13:44.080 of his movements. The scene could never have worked at 0:13:44.200 --> 0:13:47.520 normal speed because the key was how he was making 0:13:47.559 --> 0:13:51.040 a move that was not normally physically possible, and the 0:13:51.360 --> 0:13:57.360 otherworldly nature of this required immersing us to have time 0:13:57.600 --> 0:14:00.959 to really take it in. Just like Bonnie and Clyde, 0:14:01.000 --> 0:14:05.240 the slowness heightens the tension and the drama. We the 0:14:05.360 --> 0:14:09.120 audience get to squeeze every moment out of the scene 0:14:09.840 --> 0:14:12.400 rather than have it zip by. 0:14:12.360 --> 0:14:15.560 While we're reaching for our popcorn. And again, it doesn't 0:14:15.600 --> 0:14:16.840 have to be action scenes. 0:14:16.880 --> 0:14:20.840 Look at Terrence Malick's film The Tree of Life or 0:14:21.040 --> 0:14:26.360 Darren Aronofsky's Requiem for a Dream. The slow motion allows 0:14:26.480 --> 0:14:47.960 viewers to fully absorb the emotional weight of a scene. Okay, 0:14:48.000 --> 0:14:52.800 so increasing the aesthetic appeal, that's the obvious reason, But 0:14:52.920 --> 0:14:55.640 from a neuroscience point of view, I'm going to suggest 0:14:55.640 --> 0:14:58.600 there are deeper reasons why slow motion works. And this 0:14:58.720 --> 0:15:02.080 leads to my suggestion two, which is that slow motion 0:15:02.240 --> 0:15:08.240 film serves as a proxy for denser memories. So a 0:15:08.320 --> 0:15:10.760 few moments ago, I told you what happens during a 0:15:10.800 --> 0:15:14.920 life threatening situation. Although you don't actually see the event 0:15:15.120 --> 0:15:18.560 unfold in slow motion, the denser memories that you have 0:15:18.680 --> 0:15:21.120 make it seem like it must have been that way 0:15:21.240 --> 0:15:25.920 in retrospect, because there's a greater than normal amount of 0:15:26.040 --> 0:15:30.000 detail when the memory is read back out. And I 0:15:30.080 --> 0:15:34.120 suggest that slow motion film is a stand in a 0:15:34.240 --> 0:15:40.000 substitute for this extra dense memory. By watching a movie 0:15:40.080 --> 0:15:44.480 scene slowly, we get to enjoy a rich experience with 0:15:44.640 --> 0:15:48.160 plenty of time to dwell on all the details that 0:15:48.200 --> 0:15:52.240 would normally streak right past us. We have the opportunity 0:15:52.760 --> 0:15:55.960 to attend to the details and commit them to memory, 0:15:56.600 --> 0:15:59.960 just like we have after a real life high adrenaline moment. 0:16:00.440 --> 0:16:06.040 In other words, slow motion film recreates the sensation of 0:16:06.080 --> 0:16:10.640 grasping all the details, and this explains the natural partnership 0:16:10.960 --> 0:16:13.360 of slow motion videography. 0:16:13.120 --> 0:16:15.240 With high adrenaline moments. 0:16:15.720 --> 0:16:18.160 It's no accident that the first time it really got 0:16:18.280 --> 0:16:22.080 used was the ambush death scene of Bonnie and Clyde. 0:16:22.240 --> 0:16:25.760 The director Arthur Penn said in an interview quote the 0:16:25.800 --> 0:16:30.480 intention there was to get this attenuation of time that 0:16:30.560 --> 0:16:33.880 one experience is when you see something like a terrible 0:16:34.000 --> 0:16:38.680 automobile accident end quote. And giving the audience a heightened 0:16:38.720 --> 0:16:42.760 ability to catch and remember details worked well, and it's 0:16:42.800 --> 0:16:47.920 become a standard signature of high stakes moments. Arthur Penn 0:16:48.000 --> 0:16:50.920 went on to say in nineteen eighty nine, quote, God 0:16:51.000 --> 0:16:54.320 knows we've been imitated thousands and thousands of times. 0:16:54.400 --> 0:16:54.680 Now. 0:16:55.120 --> 0:16:59.160 Every time you see someone attempting violence, they go into 0:16:59.200 --> 0:17:04.000 that basics slow motion end quote. So my assertion is 0:17:04.040 --> 0:17:07.440 that when we witness a moment unfold bit by bit 0:17:07.520 --> 0:17:11.440 in the movies, we get to appreciate its import as 0:17:11.480 --> 0:17:16.399 though we were experiencing the high adrenaline moment ourselves. But 0:17:17.240 --> 0:17:21.880 not all interesting slow motion video involves high adrenaline situations, 0:17:21.920 --> 0:17:25.199 So there is more to our love of it. And 0:17:25.240 --> 0:17:28.160 this leads us to my third suggestion for the success 0:17:28.200 --> 0:17:32.480 of slow motion, which is that it extends human perception 0:17:33.320 --> 0:17:38.200 by unmasking hidden data. It allows the revelation of data 0:17:38.240 --> 0:17:40.960 that's hidden in the folds of time, just like a 0:17:41.080 --> 0:17:45.880 microscope allows us to appreciate the details of a fly's wing. 0:17:46.240 --> 0:17:49.119 And I'm not just talking about action sequences here or 0:17:49.280 --> 0:17:53.040 neo's unusual movements in the matrix, there's much more that 0:17:53.080 --> 0:17:59.360 can be unmasked. Consider something like microexpressions. These are fast 0:17:59.520 --> 0:18:05.320 movements of facial muscles that pass rapidly and unconsciously over 0:18:05.400 --> 0:18:09.639 people's faces. Now, everyone's face does this naturally all the time, 0:18:09.640 --> 0:18:13.560 but you can't really see someone else's micro expressions because 0:18:13.600 --> 0:18:16.840 they're too brief. You're not aware that you are making 0:18:16.920 --> 0:18:20.640 micro expressions, and someone watching you isn't consciously aware that 0:18:20.680 --> 0:18:23.640 you did it. But it turns out that micro expressions 0:18:23.640 --> 0:18:29.760 can carry information and can reveal secrets, including things like deception. 0:18:30.640 --> 0:18:33.720 For example, you may remember the story of Susan Smith, 0:18:34.000 --> 0:18:37.800 who claimed that her children had been kidnapped in a carjacking, 0:18:38.160 --> 0:18:41.760 when in fact she had drowned them. For several days, 0:18:41.760 --> 0:18:44.720 she was on the TV news pleading for help in 0:18:44.800 --> 0:18:48.439 finding her children, but some colleagues of mine claimed that 0:18:48.600 --> 0:18:54.080 a slowed down version of the video revealed micro expressions 0:18:54.160 --> 0:18:57.680 that suggested she was lying about the whole event. The 0:18:57.720 --> 0:19:01.919 idea is that slow motion video unmasks the world of 0:19:01.960 --> 0:19:07.679 these temporally hidden facial clues, and by unveiling things that 0:19:07.760 --> 0:19:12.119 are undetectable by consciousness, slow motion can allow not just 0:19:12.200 --> 0:19:17.439 temporal sleuthing but temporal intimacy. Consider this passage by the 0:19:17.520 --> 0:19:21.119 British sports writer Matt Rendell about the Tour de France 0:19:21.200 --> 0:19:26.119 winner Marco Pantani. Writing about the use of super slow 0:19:26.160 --> 0:19:29.080 motion cameras in sport, Rendell wrote, what I think is 0:19:29.080 --> 0:19:32.880 one of the most beautiful passages in sports writing. Here 0:19:32.960 --> 0:19:36.600 it is read by the actor Sean Judge. 0:19:36.760 --> 0:19:40.240 Now, as he arrives towards victory and the Giro Dtalia, 0:19:40.640 --> 0:19:45.199 the camera almost caresses him. The five seconds between the 0:19:45.320 --> 0:19:48.840 moment Marco appeared in the closing strait and the moment 0:19:48.920 --> 0:19:53.000 he crossed the finish line are extruded to fifteen and 0:19:53.280 --> 0:19:58.040 during seconds ba image frames his head and little else, 0:19:58.640 --> 0:20:03.360 revealing details in visible in real time and at standard resolution. 0:20:04.480 --> 0:20:07.760 A drop of sweat that falls from his chin as 0:20:07.800 --> 0:20:12.520 he makes the bend, the gaping jaw and crumpled forehead, 0:20:12.640 --> 0:20:16.680 and lines beneath the eyes that deepen as Marco rings 0:20:17.160 --> 0:20:22.040 still more speed from the mountain. Then, and it must 0:20:22.119 --> 0:20:24.919 be the moment he crosses the line. He begins to 0:20:25.160 --> 0:20:29.480 rise out of his agony. The torso rises to vertical, 0:20:30.000 --> 0:20:34.760 the arms spread out into a crucifix position, the eyelids 0:20:34.760 --> 0:20:40.399 descend and Marco's face lifts towards the sky. It is 0:20:40.480 --> 0:20:46.199 a moment of transfiguration visible only in super SlowMo or 0:20:46.400 --> 0:20:50.720 in still and only the best of the finish line 0:20:50.720 --> 0:20:56.160 photographers catch it. Super SloMo shows us something we could 0:20:56.280 --> 0:21:02.520 never otherwise see, involuntary gesture Marco never chose to reveal, 0:21:03.119 --> 0:21:07.439 perhaps because without super slow MOO technology he cannot know 0:21:07.680 --> 0:21:12.320 he makes them. The public knows more about Marco than 0:21:12.400 --> 0:21:17.120 Marco himself, a truth we are tempted to imagine, and 0:21:17.240 --> 0:21:19.920 one that has nothing to do with the race outcome 0:21:19.960 --> 0:21:23.120 as such, for the pictures frame out the finish line 0:21:23.119 --> 0:21:25.920 in the clock and show nothing of his work rate, 0:21:26.440 --> 0:21:30.040 muscular toil, or the relative positions of the riders that 0:21:30.160 --> 0:21:35.800 yield the race result. Instead, we find ourselves looking into 0:21:35.840 --> 0:21:39.600 Marco's face the way a mother and her baby might, 0:21:40.320 --> 0:21:45.000 or lovers at the moment their affection is first reciprocated. 0:21:46.760 --> 0:21:49.480 So slow motion allows us to pick up on the 0:21:49.560 --> 0:21:53.520 world that would otherwise rush past us. And in this 0:21:54.040 --> 0:21:59.440 slow world we get to luxuriate in the otherwise invisible 0:21:59.520 --> 0:22:05.080 detail with which we're always surrounded but we never see. 0:22:05.200 --> 0:22:08.400 And now we're ready from a fourth point. Slow motion 0:22:08.560 --> 0:22:14.760 video holds our attention by violating expectations. So during a 0:22:14.800 --> 0:22:20.680 lifetime of experience, your brain develops deeply wired expectations about 0:22:20.880 --> 0:22:24.800 Newtonian physics. So when a ball gets thrown to you, 0:22:24.800 --> 0:22:29.119 your brain unconsciously uses these internal models to predict where 0:22:29.200 --> 0:22:31.160 and when it's going to go, and you move your 0:22:31.520 --> 0:22:34.800 body in your hand to the right spot. These models 0:22:34.840 --> 0:22:38.040 are so ingrained into our nervous systems that if you 0:22:38.240 --> 0:22:41.399 lob a ball to an astronaut floating in zero G, 0:22:42.080 --> 0:22:44.520 she will move her hand to the wrong spot. She'll 0:22:44.920 --> 0:22:47.760 move to catch it as though she's in a normal 0:22:47.880 --> 0:22:52.840 one G environment. So part of the high level of 0:22:52.920 --> 0:22:58.600 engagement during slow motion comes from a violation of these 0:22:58.800 --> 0:23:04.479 expectations about physics. Imagine you're watching the matrix and you 0:23:04.560 --> 0:23:07.920 observe Trinity leap into the air to kick an agent. 0:23:08.440 --> 0:23:12.320 Your brain makes unconscious predictions about exactly when she's going 0:23:12.359 --> 0:23:16.879 to come back down. But to your brain's surprise, time 0:23:17.080 --> 0:23:21.800 slows down and Trinity hangs in the air longer than expected. 0:23:22.359 --> 0:23:25.000 Your expectations about when she's going to hit the ground 0:23:25.200 --> 0:23:29.960 have been violated, and this draws us in. Our brains 0:23:30.359 --> 0:23:34.560 zoom in on this because attention is maximally attracted to 0:23:34.600 --> 0:23:40.359 whatever we predict incorrectly. Conversely, when everything goes according to plan, 0:23:40.480 --> 0:23:43.359 we don't pay any attention at all. We are fond 0:23:43.520 --> 0:23:46.920 of slow motion video because it engages our attention. We 0:23:47.119 --> 0:23:51.480 constantly get the temporal predictions wrong, and so we are 0:23:51.800 --> 0:23:56.399 perpetually on alert. In fact, I did a very surprising 0:23:56.480 --> 0:23:59.360 experiment on this some years ago. I started with this 0:23:59.440 --> 0:24:04.600 hypoc prothesis that your internal model is always calibrating itself, 0:24:04.680 --> 0:24:08.800 keeping itself tuned up by comparing against the physics of 0:24:08.920 --> 0:24:12.760 the real world. So if it's running too slowly, it 0:24:12.840 --> 0:24:16.000 watches the ball hit the ground and realizes that its 0:24:16.000 --> 0:24:20.399 prediction was just slightly behind, so it speeds up its expectations. 0:24:21.040 --> 0:24:23.239 And the same if it watches the ball and it 0:24:23.280 --> 0:24:26.760 realizes that its prediction was just slightly ahead, then it 0:24:26.920 --> 0:24:31.400 slows itself down. So it uses the outside world as 0:24:31.440 --> 0:24:35.879 the ground truth to keep itself nicely calibrated. Now you 0:24:35.960 --> 0:24:39.760 might think, how would you ever prove a hypothesis like that, Well, 0:24:39.840 --> 0:24:44.240 here's how I had people compare the durations of two 0:24:44.760 --> 0:24:48.040 brief flashes on the screen. So on the screen you 0:24:48.080 --> 0:24:50.600 see a little circle that goes flash and then a 0:24:50.640 --> 0:24:53.760 moment later, another little circle that goes flash. And on 0:24:53.840 --> 0:24:57.680 every trial, I'm slightly tweaking the duration so that one 0:24:57.760 --> 0:25:00.200 is slightly longer than the other, and you just say 0:25:00.440 --> 0:25:03.320 which was longer than which? Okay, now here's the trick. 0:25:03.800 --> 0:25:08.040 I have people watch a video, for example, a camera 0:25:08.560 --> 0:25:13.120 that follows the cheetah sprinting across the serengetti. Now, if 0:25:13.119 --> 0:25:17.080 I just superimpose one flash and then the second flash 0:25:17.240 --> 0:25:19.680 on top of the video, you have no trouble saying 0:25:19.720 --> 0:25:22.119 which one was longer than which. But now I do 0:25:22.200 --> 0:25:25.640 something special. At some point in the video, it suddenly 0:25:25.680 --> 0:25:29.600 goes into slow motion. Then you might know that when 0:25:29.720 --> 0:25:33.119 cheetahs run, all four of their legs come off the ground. 0:25:33.359 --> 0:25:35.760 So now you're seeing this sleek. 0:25:35.600 --> 0:25:38.760 Animal floating in the air and you're waiting for his 0:25:38.920 --> 0:25:42.000 front pause to hit the ground. But now that we're 0:25:42.040 --> 0:25:46.439 suddenly in slow motion, your time prediction is off. You 0:25:46.560 --> 0:25:49.639 expected his legs to hit the ground, but they haven't yet. 0:25:50.280 --> 0:25:52.160 And because we evolved. 0:25:51.760 --> 0:25:53.760 In a world with no such thing as slow motion, 0:25:54.240 --> 0:25:57.960 your brain's only choice is to assume that the mistake 0:25:58.160 --> 0:26:04.800 is its own, and it compensates by slowing down its expectation. Now, 0:26:04.800 --> 0:26:06.840 how do I know the brain does this. It's because 0:26:07.080 --> 0:26:11.320 I can see how you judge the duration of a flash. 0:26:11.800 --> 0:26:16.560 During the sudden slow motion, the flash now appears to 0:26:16.720 --> 0:26:20.119 last a shorter time, about twenty seven percent shorter. 0:26:20.840 --> 0:26:21.119 Why. 0:26:22.000 --> 0:26:25.280 Roughly speaking, it's because your brain is forced to slightly 0:26:25.600 --> 0:26:29.600 tweak its estimate of the pace of time during the 0:26:29.640 --> 0:26:32.880 slow motion bit. Think of it like a clock ticking 0:26:32.960 --> 0:26:38.359 more slowly, and now the flash covers fewer ticks, and. 0:26:38.280 --> 0:26:41.840 So it is judged to last less time. 0:26:42.400 --> 0:26:45.280 I did various control versions of this experiment in which 0:26:45.320 --> 0:26:48.440 I shuffled the frames, or I shuffled all the pixels, 0:26:48.880 --> 0:26:51.679 or I ran the whole thing upside down, and in 0:26:51.760 --> 0:26:55.480 all these cases there was no distortion of the apparent 0:26:55.800 --> 0:26:59.359 duration of the flashes. It only happened when the future 0:26:59.400 --> 0:27:03.960 position of objects was predictable by physics. So let me 0:27:04.000 --> 0:27:07.560 just summarize this. When your brain is watching any scene, 0:27:08.080 --> 0:27:11.160 it's making predictions about where things will be, and if 0:27:11.200 --> 0:27:16.280 the scene suddenly changes speed, then your internal model will 0:27:16.320 --> 0:27:21.160 predict incorrectly. But I suggest the nervous system can eliminate 0:27:21.280 --> 0:27:26.840