The Hour Between Dog and Wolf: Risk-taking, Gut Feelings and the Biology of Boom and Bust. John Coates
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СКАЧАТЬ half that time to make a decision whether or not to swing the bat, or return the serve, or jump to the left or right, or reach for the puck, for the remaining time must be spent initiating the muscle or motor response.

      Even these short timeframes do not capture the truly miraculous speeds frequently demanded of the human body. In table tennis, which many of us consider a leisurely pursuit, the ball when smashed travels at 70 miles an hour, yet the distance between players may be only 14 to 16 feet, giving the returning player about 160 milliseconds to react. The difference between winning and losing has been shaved to a few thousandths of a second in reaction times. Similar reaction times are found in sprinters, who are so fast off the blocks, reacting to the starting gun in a little over 120 milliseconds, with some even approaching the 100-millisecond mark, that races increasingly feature what are called silent guns. These starting pistols produce a bang which is heard from electronic speakers placed behind each runner so that they all hear the starting signal at the same time. Without these speakers the runners in the outside lanes would hear the pistol with a fatal 30-millisecond delay, that being about the time it takes the sound of the shot to reach them.

      Or consider one of the most dangerous positions in the sporting world, the close fielder in cricket. On a cricket field, this brave soul plants himself, crouched at the ready, a mere 14 to 17 feet from the batsman, with some coming in even closer than that. Here, without the benefit of gloves, he attempts either to catch the ball as it explodes off the bat, or to get out of the way. A cricket ball, slightly larger than a baseball and much harder, rebounds off a swinging bat at speeds of up to 100 miles an hour. The fielder facing this ball must first take care not to be hit by the bat itself, and then has as little as 90 milliseconds, less than a tenth of a second, to react to the incoming projectile. One of the closest of these positions is appropriately called silly point, and in here, this close to the batsman, death can occur. One Indian player, Raman Lamba, was killed by a ball to the temple while he was fielding at short leg, another position frighteningly close to the batsman.

      Equally deadly projectiles, ones responsible for far more injuries, can be found in contact sports like karate and boxing, where punches have been clocked at terrifying speeds. Norman Mailer, reporting on the Rumble in the Jungle, when Muhammad Ali fought George Foreman in the Zairean capital Kinshasa in 1974, describes Ali warming up in the ring, ‘whirling away once in a while to throw a kaleidoscope-dozen of punches at the air in two seconds, no more – one-Mississippi, two-Mississippi – twelve punches had gone by. Screams from the crowd at the blur of the gloves.’ If Mailer’s numbers are right, one of Ali’s punches would run its course from beginning to end in about 166 milliseconds, although Foreman would only have had half that time to avoid it. In fact, later, more scientific measurement timed Ali’s left jab at little more than 40 milliseconds.

      Fig. 4. Speed of reactions. Jo-Wilfried Tsonga reaching for a volley at Wimbledon, 2011. If we assume his opponent, Novak Djokovic, hit a backhand from the baseline at about 90 mph, then Tsonga had a little over 300 milliseconds to respond.

      It should come as no surprise that athletes facing fast-moving objects like cricket balls or ice hockey pucks frequently fail to intercept them (or in boxing to avoid them). But if an athlete succeeds, say, one time out of three, as a good baseball player does when at bat, his success rate approaches that of many predators in the wild. A lion, for example, closing in on an antelope, or a wolf on a deer, catches its prey on average one time out of three. In sport, as in nature, competition has pushed reaction times right to the frontier of the biologically possible.

      Unfortunately, those of us not gifted with the reaction times of an Olympic athlete are nonetheless often called upon to respond with something like their speed, especially while on the road. A driver speeding at 70 miles an hour has as little as 370 milliseconds to avoid a car 75 feet in front that has mistakenly swerved into the oncoming lane. Here a success rate of one out of three still leaves a lot of car crashes.

      The speed demanded of our physical reactions, in the wild, in sports, on the road, even in the financial markets, raises troubling questions when lined up against certain findings in neuroscience. Take this curious fact, for instance: once an image hits the retina, it takes approximately 100 milliseconds – that is a full tenth of a second – before it consciously registers in the brain. Pause for a moment and contemplate that fact. You will soon find it profoundly disturbing. We tend to think, as we survey the world around us or sit in the stands of a sporting match, that we are watching a live event. But it turns out that we are not – we are watching news footage. By the time we see something, the world has already moved on.

      The trouble stems from the fact that our visual system is surprisingly slow. When light hits our retina, the photons must be translated into a chemical signal, and then into an electrical signal that can be carried along nerve fibres. The electrical signal must then travel to the very back of the brain, to an area called the visual cortex, and then project forward again, along two separate pathways, one processing the identity of the objects we see, the ‘what’ stream, as some researchers call it, and the other processing the location and motion of the objects, the ‘where’ stream. These streams must then combine to form a unified image, and only then does this image emerge into conscious awareness. The whole process is a surprisingly slow one, taking, as mentioned, up to one tenth of a second. Such a delay, though brief, leaves us constantly one step behind events.

      Neuroscientists have discovered another problem with the idea that we are watching the world live. An important part of this idea is the notion that our eyes objectively and continuously record the scene before us, much like a movie camera. But eyes do not operate like this. If we continuously recorded the visual information presented to us, we would waste a great deal of time (and probably suffer constant headaches) looking at blurred images as our eyes pan from one scene to another. More importantly, we would be swamped by the sheer amount of data, most of which is irrelevant to our needs. Live streaming takes up an enormous amount of bandwidth on the internet, and it does so as well in our brains. To avoid a needless drain on our attentional resources, our brain has hit upon the tactic of sampling from a visual scene, rather than filming it. Our eyes fix on a small section of our visual field, take a snapshot, then jump to another spot, take a snapshot, and quickly jump again, much like a hummingbird nervously flitting from flower to flower. We are largely unaware of this process, and do not see a blur when our eyes shift location because, remarkably, the visual system stops sending images up to consciousness while it jumps from scene to scene. Furthermore, we are unaware of these jumps and intervening blackouts because our brain weaves these images seamlessly into something that does appear much like a movie. We can perform up to five of these visual jumps per second, the minimum amount of time required for a shift in view being therefore one fifth of a second.

      If we return to sports, we can see that some numbers do not add up. How can a cricketer at silly point catch (or duck) a ball in under a tenth of a second if he is not even aware of it yet? How can he direct his attention to the ball if it takes him twice as long just to move his eyes? And when dealing with these numbers we have not even begun to consider the additional 300–400 milliseconds required for an elementary cognitive decision or inference, and the 50 milliseconds or so it takes for a motor command to be communicated by nerves to our muscles. The picture conjured by these numbers is one of an infielder frozen in the readiness stance, eyes fixed like a waxwork model, while a projectile shudders past his immobile and fragile head.

      The same questions we ask about athletes can be asked, and with more urgency, beyond the cricket pitch. How can we humans survive in a brutal and fast-moving world if our consciousness arrives on the scene just after an event is over? This is a baffling question. But asking it allows us to see what is wrong with the notion of the brain as a central processor, taking in objective information from the senses in the manner of a camera, processing this information rationally, consciously and discursively, deciding on the appropriate and desired action, and then issuing motor commands to our muscles, be they larynx or quadriceps. Each of these steps takes time, and if we were indeed СКАЧАТЬ