题目内容
To tell the difference, it is necessary to look into the brain of a sleeping person, and that is hard. But after a decade of painstaking work, a team led by Pierre Maquet at Liege University in Belgium has managed to do it. The particular stage of sleep in which the Belgian group is interested in is rapid eye movement (REM) sleep, when brain and body are active, heart rate and blood pressure increase, the eyes move back and forth behind the eyelids as ff watching a movie, and brainwave traces resemble those of wakefulness. It is during this period of sleep that people are most likely to relive events of the previous day in dreams.
Dr. Maquet used an electronic device called PET to study the brains of people as they practiced a task during the day, and as they slept during the following night. The task required them to press a button as fast as possible, in response to a light coming on in one of six positions. As they learnt how to do this, their response times got faster. What they did not know was that the appearance of the lights sometimes followed a pattern--what is referred to as "artificial grammar". Yet the reductions in response time showed that they learnt faster when the pattern was present than when there was not.
What is more, those with more to learn (i. e., the "grammar", as well as the mechanical task of pushing the button) have more active brains. The "editing" theory would not predict that, since the number of irrelevant stimuli would be the same in each case. And to eliminate any doubts that the experimental subjects were learning as opposed to unlearning, their response times when they woke up were even quicker than when they went to sleep.
The team, therefore, concluded that the nerve connections involved in memory are reinforced through reactivation during REM sleep, particularly if the brain detects an inherent structure in the material being learnt. So now, on the eve of that crucial test, maths students can sleep soundly in the knowledge that what they will remember the next day are the basic rules of algebra and not the incoherent talk from the radio next door.
Researchers in behavioral psychology are divided with regard to ______ .
查看答案
搜索结果不匹配？点我反馈
更多问题
How much is the IPCC's estimate of oil and gas reserves？
Pool Watch
Swimmers can drown in busy swimming pools when lifeguards fail to notice that they are in trouble. The Royal Society for the Prevention of Accidents says that on average 15 people drown in British pools each year, but many more suffer major injury after getting into difficulties. Now a French company has developed an artificial intelligence system called Poseidon that sounds the alarm when it sees someone in danger of drowning.
When a swimmer sinks towards the bottom of the pool, the new system sends an alarm signal to a poolside monitoring station and a lifeguard's pager. "In trials at a pool in Ancenis, near Nantes, it saved a life within just a few months, " says Alistair MeQuade, a spokesman for its maker, Poseidon Technologies.
Poseidon keeps watch through a network of underwater and overheard video cameras. AI software analyses the images to work out swimmers trajectories(轨道，轨线). To do this reliably, it has to tell the difference between a swimmer and the shadow of someone being cast onto the bottom or side of the pool. "The underwater environment is a very dynamic one, with many shadows and reflections dancing around. " says McQuade.
The software does this by "projecting" a shape in its field of view onto an image of the far wall of the pool. It does the same with an image from another camera viewing the shape from a different angle. If the two projections are in the same position, the shape is identified as a shadow and is ignored. But if they are different, the shape is a swimmer and so the system follows its trajectory.
To pick out potential drowning victims, anyone in the water who starts to descend slowly is added to the software's "pre-alert" list, says McQuade. Swimmers who then stay immobile on the pool bottom for 5 seconds or more are considered in danger of drowning. Poseidon double-checks that the image really is of a swimmer, not a shadow, by seeing whether it obscures the pool's floor texture when viewed from overhead. If so, it alerts the lifeguard, showing the swimmer's location on a poolside screen.
The first full-scale Poseidon system will be officially opened next week at a pool in High Wycombe. Buckinghamshire. One man who is impressed with the idea is Travor Baylis, inventor of the clockwork radio. Baylis runs a company that installs swimming pools -- and he was once an underwater escapologist (表演脱身术的人)with a circus. "I say full marks to them if this works and can save lives, " he says. But he adds that any local authority spending 230,000 -- plus on a Poseidon system ought to be investing similar amounts in teaching children to swim.
AI means the same as
According to IPCC, what can make up the shortfall of the oil and gas reserves？
In the last paragraph, what does the word "switch" stand for？
微信支付 
支付宝支付