《雅思阅读题库刷题练习》
You should spend about20 minutes on Questions 28-40. which are based on Reading Passage 3 on thefollowing pages.
The secret of the Yawn
A When a scientist began to study yawning inthe 1980s, it was difficult to convince some of his research students of themerits of "yawning science." Although it may appear quirky (诡异), his decision to studyyawning was a logical extension to human beings of my research in developmentalneuroscience, reported in such papers as "Wing-flapping during Developmentand Evolution. "As a neurobehavioral problem, there is not much differencebetween the wing-flapping of birds and the face- and body-flapping of human yawners.
B Yawning is an ancient, primitive act. Humansdo it even before they are born, opening wide in the womb(子宫) . Some snakes unhingetheir jaws to do it. One species of penguins yawns as part of mating. Only noware researchers beginning to understand why we yawn, when we yawn and why weyawn back. A professor of cognitive neuroscience at Drexel University inPhiladelphia, Steven Platek, studies the act of contagious yawning, somethingdone only by people and other primates.
C In his first experiment, he used apsychological test to rank people on their empathic(感情嵌入的) feelings. He foundthat participants who did not score high on compassion did not yawn back."We literally had people saying, 'Why am I looking at peopleyawning"' Professor Platek said. "It just had no effect."
D For his second experiment he put 10 studentsin a magnetic resonance imaging machine as they watched video tapes of peopleyawning. When the students watched the videos, the part of the brain whichreacted was the part scientists believe controls empathy --- the posteriorcingulate (皮层) , in the brain's middle rear. " I don't know ifit's necessarily that nice people yawn more, but I think it's a good indicatorof a state of mind," said Professor Platek. "It's also a good indicatorif you're empathizing with me and paying attention."
E His third experiment is studying yawning inthose with brain disorders, such as autism and schizophrenia, in which victimshave difficulty connecting emotionally with others. A psychology professor atthe University of Maryland, Robert Provine, is one of the few other researchersinto
yawning. He found thebasic yawn lasts about six seconds and they come in bouts with an interval ofabout 68 seconds. Men and women yawn or half-yawn equally often, but men aresignificantly less likely to cover their mouths which may indicate complexdistinction in genders." A watched yawer never yawns," ProfessorProvine said. However, the physical root of yawning remains a mystery. Someresearchers say it's coordinated within the hypothalamus (下丘脑) of the brain, the areathat also controls breathing.
F Yawning and stretching also share propertiesand may be performed together as parts of a global motor complex. But they donot always co-occur --- people usually yawn when we stretch, but we don'talways stretch when we yawn, especially before bedtime. Studies by J. I. P , G.H. A. Visser and H. F. Prechtl in the early 1980s, charting movement in thedeveloping fetus using ultrasound, observed not just yawning but a link betweenyawning and stretching as early as the end of the first prenatal trimester (预产期) .
G The most extraordinary demonstration of theyawn-stretch linkage occurs in many people paralyzed on one side of their bodybecause of brain damage caused by a stroke. The prominent British neurologistSir Francis Walshe noted in 1923 that when these hemiplegics yawn, they arestartled and mystified to observe that their otherwise paralyzed arm rises andflexes automatically in what neurologists term an "associatedresponse." Yawning apparently activates undamaged, unconsciouslycontrolled connections between the brain and the cord motor system innervatingthe paralyzed (瘫痪的) limb. It is not known whether the associated responseis a positive prognosis for recovery, nor whether yawning is therapeutic forreinnervation (再生) or prevention of muscular atrophy.
H Clinical neurology offers other surprises.Some patients with "locked-in" Syndrome, who are almost totallydeprived of the ability to move voluntarily, can yawn normally. The neuralcircuits for spontaneous yawning must exist in the brain stem near otherrespiratory and vasomotor centers, because yawning is performed by anencephalic(无脑畸形) who possess only themedulla oblongata (脊髓延髓). The multiplicity of stimuli of contagious yawning,by contrast, implicates many higher brain regions.