Powers of Self-suggestion来源：www.examda.com
Most systems of medicine are based on theater. With leeches, acupuncture needles, vitamin pills or whatever stage prop is appropriate for the time and culture, the healer artfully evokes the patient’s powers of self-suggestion, which are responsible for whatever healing may occur. 来源：www.examda.com
Western medicine operates on a different plane. For one thing, it has the most impressive props - expensive medicines, elaborate rituals and mysterious high-tech machines with a white-gowned cast to operate them. For another, it evokes the patient’s auto suggestive powers all the more forcefully by pretending to ignore them. This mysterious gift of self-healing is cloaked with an anodyne label, the "placebo effect", and recognized only as a nuisance likely to confound clinical trials. But the placebo (Latin for "I will please") and its shadowy twin the nocebo ("I will harm") are much more than methodological problems: they lie at the heart of every interaction between doctor and patient.
How they work no one knows. But the brain rules the body in many subconscious ways, including its control of the body’s major hormones and its subtle influence over the immune system. So it’s possible that, in ways yet unknown, expectations about health or disease are sometimes translated into a bodily reaction that fulfills them.
The power of these effects is hard to overstate. A rule of thumb is that 30 percent of patients in the placebo half of a drug trial (i.e. those who unknowingly receive a dummy pill instead of the real thing) will experience an improvement in symptoms. But the proportion may be much higher. Just like real drugs, placebo pills can produce stronger effects in larger doses. Patients will report greater relief when given a larger pill, or two dummy capsules instead of one.
Doctors’ expectations also contribute to the awesome power of the placebo effect. In a study of tooth extractions, patients were given either a painkiller or sham drugs. Some dentists were assigned to give either drug, without knowing which, but other dentists knew they would be giving only sham drugs. The patients whose dentists thought they had at least a 50-50 chance of giving a painkiller suffered significantly less pain.
Presumably, doctors transmit their expectations to the patient through subtle cues, often without knowing they are doing so. For this reason, all properly designed drug trials are double blind. But given that both groups can often guess from the side effects, even this precaution may not always crush the generation of expectancies.
2. What dose the term "the placebo effect" mean?
A) It means the mind-troubling effect.
B) It means the psychological effect.
C) It means the harmful effect.来源：www.examda.com
D) It means the theatrical effect.
3. What does "them" (the last word in paragraph 3) refer to?
A) Clinical trials.
B) The body's major hormones.
C) Expectations about health or disease.
D) Many subconscious ways.
4. Why did the patients whose dentists thought they had at least a 50-50 chance of being given a painkiller suffer significantly less pain?
A) Because of doctors' expectations.
B) Because of the placebo effect.
C) Because of the healing power of the medicine taken.
D) Because of the excellent medical skills of the doctors.
5. What does the author mean by saying that for this reason, all properly designed drug trials are double blind (in the last paragraph)?
A) The physician and the patient are both ignorant of the healing power of the medicine.
B) The physician doesn't know whether the given pill is real or fake.
C) The patient doesn't know whether the given pill is real or fake.
D) Neither the physician nor the patient knows whether the given pill is real or fake.
Keys: ABCAD
