Wednesday, 25 June 2014

Neuroscience: The man who saw time freeze

(Flickr/Marjan Lazarevski/CC BY-ND 2.0)
(Flickr/Marjan Lazarevski/CC BY-ND 2.0)
One day, a man saw time itself stop, and as David Robson discovers, unpicking what happened is revealing that we can all experience temporal trickery too.
It started as a headache, but soon became much stranger. Simon Baker entered the bathroom to see if a warm shower could ease his pain. “I looked up at the shower head, and it was as if the water droplets had stopped in mid-air”, he says. “They came into hard focus rapidly, over the course of a few seconds”. Where you’d normally perceive the streams as more of a blur of movement, he could see each one hanging in front of him, distorted by the pressure of the air rushing past. The effect, he recalls, was very similar to the way the bullets travelled in the Matrix movies. “It was like a high-speed film, slowed down.”
The next day, Baker went to hospital, where doctors found that he had suffered an aneurysm. The experience was soon overshadowed by the more immediate threat to his health, but in a follow-up appointment, he happened to mention what happened to his neurologist, Fred Ovsiew at Northwestern University in Chicago, who was struck by the vivid descriptions. “He was a very bright guy, and very eloquent” says Ovsiew, who recently wrote about Baker in the journal NeuroCase. (Baker’s identity was anonymised, which is typical for such studies, so this is not his real name).
"I looked up at the shower head, and it was as if the water droplets had stopped in mid-air" (Flickr/Umberto Rotundo/CC BY 2.0)
It’s easy to assume that time flows at the same rate for everybody, but experiences like Baker’s show that our continuous stream of consciousness is a fragile illusion, stitched together by the brain’s clever editing. By studying what happens during such extreme events, researchers are revealing how and why the brain plays these temporal tricks – and in some circumstances, they suggest, all of us can experience time warping.
Although Baker is perhaps the most dramatic case, a smattering of strikingly similar accounts can be found, intermittently, in medical literature. There are reports of time speeding up – so called “zeitraffer” phenomenon – and also more fragmentary experiences called “akinetopsia”, in which motion momentarily stops. For instance, travelling home one day, one 61-year-old woman reported that the movement of the closing train doors, and fellow passengers, was in slow motion and “broken up”, as if in “freeze frames”. A 58-year-old Japanese man, meanwhile, seemed to be experiencing life like a badly dubbed movie; in conversation, he found that although others’ voices sounded normal, they were out of sync with their faces. There may be many more unreported cases, says Ovsiew. “Since it’s a transient phenomenon, it could often be overlooked.”
(Getty Images)
Such experiences almost always accompany problems like epilepsy or stroke. Baker was only 39 at the time of his experience, which seems to have been caused by a weakened blood vessel that began bleeding while he was carrying some heavy boxes. The result was a relatively large patch of neural damage in the right hemisphere. “In the scans, it looks like there’s a cigar in my head,” he jokes today.
Yet why did this affect Baker’s time perception? Some clues could come from studies that have attempted to pinpoint the regions responsible for our perception of time. Of particular interest is an area of the visual cortex, called V5. This region, which lies towards the back of the skull, has long been known to detect the motion of objects, but perhaps it has a more general role in measuring the passing of time. When Domenica Bueti and colleagues at the University Hospital of Lausanne, Switzerland zapped the area with a magnetic field to knock out its activity, her subjects found it tricky to do two things: they struggled to track the motion of dots on a screen, as would be expected,  but also found it hard to estimate how long some blue dots appeared too.
One explanation for this double-failure is that our motion perception system has its own stopwatch, recording how fast things are moving across our vision – and when this is disrupted by brain injury, the world stands still. For Baker, stepping into the shower might have exacerbated the problem, since the warm water would have drawn the blood away from the brain to the extremities of the body, further disturbing the brain’s processing.
Perhaps our brain has a 'stopwatch' for judging how fast things fall, or move - when it breaks, time warps (Flickr/Laszlo Ilyes/CC BY 2.0)
It is just one possibility; not all patients with time warping experiences have damage to V5, so other cogs in the brain’s time-keeping apparatus may also play a role.
Another explanation comes from the discovery that our brain records its perceptions in discrete “snapshots”, like the frames of a film reel. “The healthy brain reconstructs the experience and glues together the different frames,” says Rufin VanRullen at the French Centre for Brain and Cognition Research in Toulouse, “but if brain damage destroys the glue, you might only see the snapshots.”
The brain constructs our smooth perception of reality from a series of intermittent snapshots (Flickr/Janos Csongor Kerekes/CC BY-ND 2.0)
We may all experience the normal smooth picture breaking down occasionally. For starters, if you’ve ever looked at overtaking cars on the motorway, their wheels can seem to stand still. This happens because the brain’s intermittent snapshots fail to capture the wheel’s motion fully. If, for example, it has made a full rotation between each “frame”, it will seem to be in exactly the same position each snapshot, giving the illusion that it is stationary.
And users of LSD often report “visual trails” following moving objects, a bit like the trails of bullets in The Matrix movie. VanRullen suspects this might arise because the brain somehow overlaps those sensory snapshots, rather than refreshing its picture anew.
Users of LSD report seeing moving objects with blurred trails (SPL)
Reports of time standing still are also common during a life-threatening accident; in one survey of people who had skirted close to death, more than 70% reported the feeling that the event occurred in slow motion. Some researchers claim that they are simply an artefact of memory, since the intense emotions lead us to lay down more details, so that we believe that the event lasted for longer only in hindsight. But the descriptions certainly sound close to those reported by the neurological patients, suggesting there may be some overlap.
For example, one person told researchers in the 1970s how they vividly remembered seeing the face of a train’s engineer during a near fatal collision: “It was like a movie run slowly so the frames progress with a jerky motion – that was how I saw the face”.
What’s more, Valtteri Arstila at University of Turku, Finland, points out that many of these subjects also report abnormally quick thinking. As one pilot, who’d faced a plane crash in the Vietnam War, put it: “when the nose-wheel strut collapsed I vividly recalled, in a matter of about three seconds, over a dozen actions necessary to successful recovery of flight attitude”. Reviewing the case studies and available scientific research on the matter, Arstila concludes that an automatic mechanism, triggered by stress hormones, might speed up the brain’s internal processing to help it handle the life or death situation. “Our thoughts and initiation of movements become faster – but because we are working faster, the external world appears to slow down,” he says. It is even possible that some athletes have deliberately trained themselves to create a time warp on demand: surfers, for instance, can often adjust their angle in the split second it takes to launch off steep waves, as the water rises overhead.
Could pro surfers and other athletes perceive time more slowly than the rest of us? (Thinkstock)
For Baker, the experience was a one-off, and after surgery to remove the damaged blood vessels, he has now made a full recovery. He remains remarkably upbeat about his condition, pointing out that in some ways it has actually been of benefit. Beforehand, he had been somewhat taciturn, particularly around strangers – a tendency that had even been labelled a disability by his school. But today, his shyness has gone – a fact that is clearly evident as he chats happily during our telephone conversation. “It was more than just feeling a little more forthcoming – I suddenly felt compelled to talk,” he says. Ovsiew has verified the report with Baker’s wife. “She confirmed that he was calmer, more talkative, and more friendly in social situations,” says Ovsiew.
The experience of time freezing around him, meanwhile, has given him new wonder at the fragility of our conscious experiences. “It was a really concrete example of how something very localised in brain can change your whole perception of the world,” he says. “One minute I was fine, the next minute I was in an altered reality.”

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