Sci-Tech

What defines our perception of time? David Eagleman may just have an answer.

By Mandy De Waal 28 November 2011

Ever wished you could slow time down or make it speed up? Scientist and New York Times bestselling author David Eagleman may not have discovered a potion that enables people to change their experience of time, but his research on brain time is helping humanity understand the neural mechanisms of time perception. By MANDY DE WAAL.

Professor Gibberne wanted a little more out of life. Instead of plodding from one second to the next, he desired to dash through the world three times or four times faster than other mortals. The hero of H.G. Wells’ short work of science fiction called “The New Accelerator”, Gibberne earned modest celebrity and great respect for his work on drugs that affected the nervous system. But the research scientist wanted to achieve the impossible – to radically alter his experience of time.

In Wells’ story, Gibberne creates a potion that enables whoever consumes it to speed through time, not just two or three times quicker, but thousands of degrees faster. When the curious professor consumes his concoction, time seems to slow while he speeds through life and is able to witness the flapping wings of a bee which appear to move at the languid pace of a snail.

Gibberne is the stuff of imagination but like the engrossed professor, real scientists throughout the ages have been fascinated with researching time. Russian explorer and biologist Karl Ernst von Baer pioneered the study of subjective biology by researching how different organisms observed time; while Swiss geologist Albert Heim undertook the first systematic study of how people perceived time during near-death experiences.

Decades later in the seventies, professor of psychiatry Russell Noyes and clinical psychologist Roy Kletti would revisit Heim’s work in their study of depersonalisation, which surveyed over a hundred people who experienced life-threatening dangers. Their survey showed that in the face of a near death, people’s experience of time was altered.

Like the imaginary Gibberne and his real world counterparts Von Baer, Heim, Noyes and Kletti, Dr David Eagleman has spent much of his life exploring how we experience those seconds, minutes and hours that make up our existence.

“In my laboratory what we have discovered over the last decade is that time isn’t what you think it,” says the head of the neuroscience research laboratory at Baylor College of Medicine. “We can make you think that a duration lasted or shorter than it actually did; we can make you think that something came before something else; we can make you think that two things are simultaneous when they are actually not; and so on. What this indicates to us is that time is not a river that is passively flowing past and we are tracking it, but that the brain is actively constructing its sense of time.”

Eagleman says that scientists have known for a long while that people’s perception of time is flawed. “We all accept the reality presented to us, but the truth is that we are like fish in water trying to describe water. We have never seen anything other than the water so it is difficult to even know what it is. But if a bubble comes up in the water one day, that’s when you say: ‘Wow. Something strange is going on here.’ And that is what things like perceptual illusions are to us. It is like a bubble in the water when we say things aren’t exactly what we thought they were and it allows us to understand how the brain is constructing this illusion around us.”

Writing for that intellectual colloquium Edge.org, Eagleman states that the days of humans thinking of time as a river that’s evenly flowing and ever advancing are over. “Time perception, just like vision, is a construction of the brain and is shockingly easy to manipulate experimentally. We all know about optical illusions, in which things appear different from how they really are; less well known is the world of temporal illusions. When you begin to look for temporal illusions, they appear everywhere.” Eagleman offers an example of a common temporal illusion by way of the cinema, which is nothing more than a series of static images that when projected onto a screen appears to be a continuous and smooth flowing scene.

As a child Eagleman fell from a roof and experienced a change in his perception of time, and wanted to recreate this as an experiment in his lab. But to discover whether time really does slow down during a frightening event, or whether this is pure illusion, Eagleman needed a “perceptual chronometer”.  The neuroscientist tasked one of his graduates with building a tool that would help measure how people perceived time.

The result was a battery powered device that could strap on a test subject’s wrist that had a circuit board and an LED display. As big as a mobile phone, the device displayed a series of numbers at a rate quicker than they could be perceived. If time really did slow down during a deadly situation the subjects would surely be able to read the digits. Now all Eagleman required was a large enough dose of terror, a heart palpitating event that would simulate a near-death experience but which wouldn’t harm his subjects.

Free falling is possibly one of the most thrilling and frightening experiences a human can have, which is why adrenalin junkies throw themselves out of planes and off bridges. But they do this with the right safety accoutrements to simulate the fear of plummeting with some reasonable guarantee of a safe landing. Eagleman latched onto this idea and created a test environment using a massive steel structure that allowed his subjects to fall backwards for close on 35 metres before landing safely in a net.

When his test subjects watched their peers fall and guessed how long the duration of the drop was, they were incredibly accurate, saying it lasted little more than two seconds. However when people went into free fall, they couldn’t see the numerical digits on their wrist device and time predictably appeared to slow. When asked how long they had taken to fall, they reported the experience as lasting much longer than it actually did.

“How do we make sense of the fact that participants in free fall reported a duration expansion yet gained no increased discrimination capacities in the time domain during the fall? The answer is that time and memory are tightly linked. In a critical situation, a walnut-size area of the brain called the amygdala kicks into high gear, commandeering the resources of the rest of the brain and forcing everything to attend to the situation at hand,” writes Eagleman. “When the amygdala gets involved, memories are laid down by a secondary memory system, providing the later flashbulb memories of post- traumatic stress disorder. So in a dire situation, your brain may lay down memories in a way that makes them ‘stick’ better.”

What happens when you recall these memories? Because they are denser than other memories, they appear to last longer than they actually did in real time. “This may be why time seems to speed up as you age: you develop more compressed representations of events, and the memories to be read out are correspondingly impoverished,” says Eagleman.

“Time and memory are intertwined,” he says, speaking to iMaverick from his lab in Houston, Texas. “When you look back on an event, how long you think it lasted depends on how many new memories you think you have. How much new memory your brain wrote down. So when you had a really exciting weekend full of novelty, you look back on it and you think: ‘Wow. It feels like forever since it was Friday.’ When you have a boring standard weekend it seems to have disappeared,” he says.

“I think this is also why time speeds up when you are older, because when you are older you have figured out the rules of the world and your brain isn’t writing much down in contrast to when you are a child; everything is new and your summer is full of new memory, so it seems to last longer,” says Eagleman.

The big question then is can you play with your brain so as to make time appear faster or slower, or to consciously manipulate time? “What I implement in my daily life is always seeking novelty and that includes just things like driving home a different route from work every day. If you take the same route home from work every day, it seems like there is no time at all there. If you take a new route, even if it is the same distance, it feels longer. Generally when I have the choice to do something that I have done before, or to take a different path at it, I always try to take the different path,” Eagleman advises.

So if you want holidays or weekends to last longer, make them novel – do something new and different. That way, when your brain records these memories, they’ll be more compact, so when recalled, these pleasurable times of your life will at least appear to have lasted that bit longer. DM



Read more:

  • The Possibilian in The New Yorker;
  • Brain Time by David Eagleman in The Edge’s “Third Culture”;
  • When Life Flashes Before Your Eyes: A 15-Story Drop to Study the Brain’s Internal Timewarp in PopSci;
  • Time doesn’t actually slow down in a crisis in Discover Magazine;
  • Visit David Eagleman online at Eagleman.com.

Photo: REUTERS

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