Why do we love slow motion video?

David Eagleman is guest blogging this week.

During my studies of human time perception I’ve become fascinated by a peripheral question: why do we love slow-motion photography so much? Movies like The Matrix and 300 use time warping as a standard tool in their cinematographic toolbox. The success of this approach has leaked into commercials and music videos and almost every other action film on the scene. Even comedian Dave Chappelle has noted our love of slow-mo: to demonstrate that everything “looks cooler in slow motion,” he shows how his experience in the laundromat changes from mundane to sexy as soon as it is replayed slowly (in slow motion, the old woman by the washing machine becomes a young model tossing her locks of hair in the breeze).

So why is time warping so successful and engaging? I propose three reasons.

1: More time gives a proxy for denser memories

I recently posted about the claim that time slows during a life-threatening event. To the best that we were able to address this, our studies suggested that the impression of slowed time is a trick of memory: denser memories are laid down during salient events, yielding more than the normal amount of detail when read back out. So one can speculate that slow motion video gives a proxy for this extra-dense memory: by presenting a scene slowly, one can enjoy a rich experience with plenty of time to dwell on all the details that normally leak away from us. In other words, when a movie scene is presented slowly we can grab onto and remember many details, just as we do during a real-life high-adrenaline moment.

This idea can explain the natural introduction of slow motion videography into scenes of violence. The first American movie to use slow motion was Bonnie and Clyde. Much to the shock of the audience, the cinematography went into balletic slow motion as the two main characters of the movie met their violent end under a hailstorm of bullets from the police. As Bonnie and Clyde lived out their final seconds, the audience got several extra seconds in which to appreciate it. The director, Arthur Penn, had an intuition about what he was doing; he reported: "The intention there was to get this...attenuation of time that one experiences when you see something, like a terrible automobile accident." Although critics at the time called the slowing of the death scene gratuitous and callous, the idea caught on. Giving the audience a heightened ability to catch and remember details worked well and has been imitated thousands of times since.

But note that not all interesting slow-mo videography involves high-adrenaline situations, indicating that there may be more to it--and this leads us to the next point.

2: Slow motion extends human perception by unmasking hidden data

From a transhumanist perspective, slow motion videography is a technology that allows us to extend our senses beyond their natural capacities. It allows the revelation of data hidden in the folds of time, just as a microscope allows us to appreciate the wonders of a fly's wing or a microbe's choreography.

As one example, consider microexpressions, the fast movement of facial muscles that pass rapidly and unconsciously over peoples’ faces. Microexpressions are normally not accessible to awareness (the owner’s or the viewer’s) because they are too brief. But they can reveal all sorts of secrets, including when someone is lying. For example, when Susan Smith got on the TV news to plead for help in finding her kidnapped children, a slowed-down version revealed micro-expressions that could suggest (at least, with the benefit of hindsight) that she was lying about the whole event. Slow motion video unmasks the world of these temporally hidden facial clues.

Moreover, by unveiling things undetectable by consciousness, slow motion can allow not just temporal sleuthing but temporal intimacy. Consider this passage by the British sports writer Matt Rendell about the 1998 Tour de France winner Marco Pantani. Writing about the use of super slow-motion cameras in sport, Rendell penned what I consider to be one of the most beautiful passages in sports writing:

Now, as he rides towards victory in the Giro d’Italia, the camera almost caresses him. The five seconds between the moment Marco appeared in the closing straight and the moment he crossed the finish line are extruded to fifteen enduring seconds. The image frames his head and little else, revealing details invisible in real time and at standard resolution: a drop of sweat that falls from his chin as he makes the bend, the gaping jaw and crumpled forehead and lines beneath the eyes that deepen as Marco wrings still more speed from the mountain. Then – and it must be the moment he crosses the line – he begins to rise out of his agony. The torso rises to vertical, the arms spread out into a crucifix position, the eyelids descend, and Marco's face lifts towards the sky. It is a moment of transfiguration, visible only in super slo-mo or in still – and only the best of the finish-line photographers catch it. Super slo-mo shows us something we could never otherwise see – involuntary gestures Marco never chose to reveal, perhaps because, without super slo-mo technology, he cannot know he makes them. The public knows more about Marco than Marco himself: a truth, we are tempted to imagine, and one that has nothing to do with the race outcome as such, for the pictures frame out the finish line and the clock, and show nothing of his work rate, muscular toil or the relative positions of the riders that yield the race result. Instead, we find ourselves looking into Marco’s face the way a mother and her baby might, or lovers at the moment their affection is first reciprocated.

3: Time-warped video holds our attention by violating expectations

Finally, note that brains develop deeply-wired expectations about Newtonian physics. For example, when a ball gets thrown in the air, your brain unconsciously uses its internal models to predict where and when is it going to hit. These models are so ingrained into our nervous systems that if you lob a tennis ball to an astronaut in zero-g, he will still move his hand to catch it as though he’s in a normal 1-g environment.

I suspect that the high level of engagement during slow-mo video is related to a violation of these expectations about physics. Imagine you are watching The Matrix, and Trinity leaps into the air to kick an agent. Your brain makes (unconscious) predictions about exactly when she’s going to come back down. But, shockingly, time slows down and Trinity hangs in the air longer than expected. Your expectations about when she will land have been violated.

As for why we find this interesting, it is probably because these violations hold our attention. Attention is maximally engaged when predictions are violated (an old idea that Jeff Hawkins summarizes nicely in his book On Intelligence). So my speculation, then, is that we like time-warped video because it is very attention-engaging: we are constantly getting the temporal predictions wrong, and so we are constantly on alert. In support of this, a very engaging style of cinematography is to rapidly alternate between speeding and slowing (think of the battle scenes in 300), thereby holding our attention throughout.


David Eagleman is a neuroscientist and a writer. His book of literary fiction, Sum, debuted internationally this month.

Will you perceive the event that kills you?

David Eagleman is guest blogging this week.

When light strikes your eyes, it takes some hundreds of milliseconds before you become conscious of the event. As a consequence, you are always living in the past. This strange fact of our existence is well known is neuroscience, but there’s an interesting, underappreciated consequence: you may not ever become aware of the thing that kills you.

Cormac McCarthy addresses this point in his post-apocalyptic novel The Road, in a scene in which the main character has his pistol leveled on a miscreant. The malefactor challenges: “you won't shoot....they [my companions] will hear the shot.”

The protagonist replies, “Yes they will. But you won’t.”

“How do you figure that?”

“Because the bullet travels faster than sound. It will be in your brain before you can hear it. To hear it you will need a frontal lobe and things with names like colliculus and temporal gyrus and you won't have them anymore. They’ll just be soup.”

One way to appreciate the slowness of your perception is to compare it to the speed of mechanical devices. Take this incredible, sobering "anatomy of a crash," as described in an Australian magazine and echoed on Tom Vanderbilt’s blog. With fine-grained temporal resolution, it analyzes what happens when a stationary Ford Falcon XT sedan is struck in the driver’s door by another vehicle traveling at 50 kilometers per hour:

0 milliseconds - An external object touches the driver’s door.
1 ms - The car’s door pressure sensor detects a pressure wave.
2 ms - An acceleration sensor in the C-pillar behind the rear door also detects a crash event.
2.5 ms - A sensor in the car’s centre detects crash vibrations.
5 ms - Car’s crash computer checks for insignificant crash events, such as a shopping trolley impact or incidental contact. It is still working out the severity of the crash. Door intrusion structure begins to absorb energy.
6.5 ms - Door pressure sensor registers peak pressures.
7 ms - Crash computer confirms a serious crash and calculates its actions.
8 ms - Computer sends a “fire” signal to side airbag. Meanwhile, B-pillar begins to crumple inwards and energy begins to transfer into cross-car load path beneath the occupant.
8.5 ms - Side airbag system fires.
15 ms - Roof begins to absorb part of the impact. Airbag bursts through seat foam and begins to fill.
17 ms - Cross-car load path and structure under rear seat reach maximum load.
Airbag covers occupant’s chest and begins to push the shoulder away from impact zone.
20 ms - Door and B-pillar begin to push on front seat. Airbag begins to push occupant’s chest away from the impact.
27 ms - Impact velocity has halved from 50 km/h to 23.5 km/h. A “pusher block” in the seat moves occupant’s pelvis away from impact zone. Airbag starts controlled deflation.
30 ms - The Falcon has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.
45 ms - Occupant and airbag move together with deforming side structure.
50 ms - Crash computer unlocks car’s doors. Passenger safety cell begins to rebound, pushing doors away from occupant.
70 ms - Airbag continues to deflate. Occupant moves back towards middle of car.
Engineers classify crash as “complete”.
150-300 ms - Occupant becomes aware of collision.

The last line is the zinger. Early studies by Benjamin Libet suggest that the last line should perhaps read as high as 500 ms, although others, such as Daniel Dennett, have correctly pointed out that it is impossible to measure the moment of onset of conscious experience, so the exact timing will never be known.

Just as the explorer David Livingstone appreciated the biological kindness of stress-induced analgesia, there may an equivalent kindness in the slowness of perception.

David Eagleman is a neuroscientist and a writer. His book of literary fiction, Sum, debuted internationally this month.

Re-visiting what happens during life-threatening situations

David Eagleman is guest blogging this week.

One interesting direction of transhumanism lies in the possibility of teasing out latent talents buried within us. In its grandest form, the question becomes: what are the possibilities for unearthing some sort of “superpowers”? The detection of exceptional abilities would not only (potentially) improve the human condition, but also give us stunning new data to draw from for our biological theories.

The search for hidden powers is by no means new, of course. Artists have long used drugs to enhance creativity, and students around the globe are pounding energy drinks to optimize their cognitive abilities.

But my interest, in particular, is in time perception, and so my next three posts will be about issues I’m chewing on in that domain. As George covered earlier, a few years ago I set out to address our capacity to perceive the world in slow motion. We have all experienced (or heard described) that time seems to “slow down” during a car accident, or during other high-adrenaline situations. So my laboratory performed experiments to directly address this, and, to my slight disappointment, we could find no evidence that people could really see in slow motion. Instead, they all seemed to believe that a scary event lasted longer—but only when they were reconstructing the event retrospectively. This suggested that the duration expansion during fear was a trick of memory. During a frightening event the emergency control centers in your brain quickly come online and lay down memories on a secondary memory track. Under normal circumstances, your memory is quite leaky; in frightening situations, memories tend to stick better. The end result is that we are not actually able to see in slow motion like Neo in The Matrix, but instead that consciousness seems to be postdictive, that is, constructed in retrospect. So much for the seeing-in-bullet-time superpower. Bummer.

However, since the publication of that study, I have received dozens of emails from people describing their life-threatening experiences. Despite our negative results in the slow-mo domain, there are clearly interesting things going on in the moment of an accident. I’ve noticed a few patterns. First, it seems that the duration dilation is reported only when someone sees the event approaching, as in sliding on the ice toward a truck. When a person is blindsided, there seems to be something like a loss of time: everything is over before you know what happened. So the duration dilation seems to require anticipation. This is consistent with the need for the emergency control centers to kick into gear.

The second thread in virtually all the descriptions is a total calmness about the life-threatening event as it takes place. As a historical example, in 1843, the African explorer David Livingstone was sprung upon by a lion. The lion shook Livingstone in his jaws the way a dog shakes prey. When someone else raised a rifle, the lion dropped Livingstone and went after him instead. As a result of the event, Livingstone lost power in his left arm for the rest of his life. But the extraordinary thing was that Livingstone reported that he had felt “no sense of pain nor feeling of terror, though quite conscious of what was happening.” Similarly, it is commonplace for a soldier to not notice wounds, even mortal wounds, until after the battle is over. This appears to be the result of what’s known as “stress-induced analgesia.” All the body’s resources are marshaled for fighting (or running) one’s way out of a situation, not for tending to wounds. This analgesia depends on the release of chemicals in the brain called endorphins. So that’s good news for humans who end up in bad situations. As Livingstone interpreted it, it is “a merciful provision by our benevolent Creator for lessening the pain of death.”

What’s a bit stranger, and unaddressed in the literature, is that this calmness is often accompanied by a bizarreness of thought. For example, one man reported that while he was sliding along the asphalt after being thrown from his motorcycle, he composed a little song to the tune of his helmeted head bouncing against the asphalt. No fear, no panic, just a calm little tune. And I experienced something similar when I was younger and fell from a roof. As I plummeted toward what was likely to be my death, I was calmly thinking how similar the fall was to Alice’s fall down the rabbit hole in Alice in Wonderland. No fear, no panic, just a crystal clear thought about a moment from a children’s book.

The final commonality is that people claim to have made very good decisions, especially as regards motor actions—as in “I decided to jump onto the approaching car hood,” or “I darted out of the way with no hesitation.” Of course, there is no way to assess the subjective impressions of those who made the wrong decisions, because they can’t tell us; this leaves open the possibility that the survivors who write to me are those who enjoyed a bit of luck, and their brains retrospectively construct a good story about the potency of their decision-making.

At this stage, there’s one more thing I want to look into, if I can figure out a way to do it scientifically. I’d like to better understand the common claim that “my life flashed before my eyes.” Does this really happen? It is difficult to know, at first blush, whether the statement is metaphorical. At least in some cases, the statement becomes something people say when they are trying to be clear that an event was extremely frightening. It becomes a linguistic equivalent of “that was really scary”, in the same way that saying “I was on cloud nine” is not meant to really imply something about levitation or cumulonimbi. The question is whether it is being used metaphorically in some cases, or in all cases. Take this example from another motorcycle accident victim:

…it was at this stage that I started to think of some of the people I had gone to school with in both Primary and Secondary School. I thought of the names of teachers and students that I hadn’t thought of or remembered in years and could see their faces and the school yards as vividly as if it were only a few days ago. I could hear their voices in my head and was saying their names out loud.

The challenge for brain researchers is to understand whether there is a nugget of something real at the heart of these claims, something that would force a change of our views about the capacity of memory, the potential speed of running through recall, and the power of calcified memories to suddenly shoot up to consciousness. Not surprisingly, these questions have not been addressed because of the difficulty in setting up a safe and meaningful experiment. Are there any ideas about what’s happening in these situations, or how to address these in an experiment? I’ll be very interested to hear readers post their own experiences or hypotheses.

In my next two posts I’ll address some different aspects of slow motion and the speed of perception…

David Eagleman is a neuroscientist and a writer. His book of literary fiction, Sum, debuted internationally this month.