2. 外语
  3. In the early 20th century, a horse named Clever Hans was believed capable of counting and other impressive mental tasks. After y

In the early 20th century, a horse named Clever Hans was believed capable of counting and other impressive mental tasks. After y

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问题     In the early 20th century, a horse named Clever Hans was believed capable of counting and other impressive mental tasks. After years of great performance, psychologists discovered that though Hans was certainly clever, he was not clever in the way everyone expected. The horse was cunningly (聪明地) picking up on tiny, unintentional bodily and facial cues given out not only by his trainer, but also by the audience. Aware of the "Clever Hans" effect, Lisa Lit at the University of California, Davis, and her colleagues wondered whether the beliefs of professional dog handlers might similarly affect the outcomes of searchers for drugs and explosives. Remarkably, Dr. Lit found, they do.
    Dr. Lit asked 18 professional dog handlers and their dogs to complete brief searches. Before the searches, the handlers were informed that some of the search area might contain up to three target scents (气味), and also that in two cases those scents would be marked by pieces of red paper. What the handlers were not told was that none of the search areas contained the scents of either drugs or explosives. Any "detections" made by the teams thus had to be false.
    The findings reveal that of 144 searches, only 21 were clean (no alerts). All the others raised one alert or more. In total, the teams raised 225 alerts. While the sheer number of false alerts struck Dr. Lit as fascinating, it was where they took place that was of greatest interest.
    When handlers could see a red piece of paper, allegedly marking a location of interest, they were much more likely to say that their dogs signaled an alert. The human handlers were not only distracted on almost every occasion by the stimulus aimed at them, but also transmitted that distraction to their animals — who responded accordingly. To mix metaphors, the dogs were crying "wolf at the unconscious signal of their handlers.
    How much that matters in the real world is unclear. But it might. If a handler, for example, unconsciously "profiled" people being sniffed (嗅) by a drug- or explosive-detecting dog at an airport, false positives could abound (大量存在). That is not only bad for innocent travelers, but might distract the team from catching the guilty.  
What did the dog handlers learn before the searches?
选项 A、There was actually no target scent in the search area.
B、Each search area contained three target scents.
C、Their dogs were expected to find the scents of red paper.
D、Some target scents may be labeled with a special mark.
答案D
解析 根据题干中的Before the searches将本题出处定位到第2段第2句。该句用两个that从句说明警犬训练员被告知的两种情况，其中提到：…in two cases those scents would be marked by pieces of red paper(……在两种情况下，这些气味将会用红色的纸片标注出来)，也就是说，警犬训练员知道一些目标气味可能会用特殊标识(即红色纸片)标记出来，故答案为[D]。文中提到没有告诉警犬训练员这些搜索区域没有毒品和爆炸物的气味，[A]与之矛盾，故排除。[B]中的each search area与第2句提到的someof the search area矛盾，故排除。文中提到气味将会用红色的纸片标注出来，但并未说是红色纸片的气味，[C]是针对scents would be marked by pieces ofred paper设的干扰项。
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大学英语四级

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