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题库 / GMATAdvanced-CR-39
Researchers conditioned a group of flies to associate a particular odor with a weak electric shock. Twenty-four and forty-eight hours later the researchers conducted tests on the flies, both individually and in groups, to determine whether the flies retained the conditioning. When tested individually, the flies were significantly less likely to avoid areas marked with the odor. The researchers hypothesized that in the presence of the odor, a fly that retains the conditioned association gives off an alarm signal that arouses the attention of any surrounding flies, retriggering the association in them and thereby causing them to avoid the odor.
The researchers’ hypothesis requires which of the following assumptions?
The flies do not give off odors as alarm signals.
Flies that did not avoid the odor when tested individually were not merely following other flies’ movements when tested in a group.
Flies that did not avoid the odor when tested individually were less likely than the other flies to avoid the odor when tested in a group.
Prior to their conditioning, the flies would likely have found the odor used in the experiment to be pleasant.
An electric shock was used during the flies’ conditioning and during the later tests.
B. Correct. Suppose that the flies that did not avoid the odor when tested individually were more likely to avoid the odor when in groups. This may be simply because these flies were following the movements of the flies that were triggered. That is, the signal did not cause the other flies' reactions. Instead, the movements of the triggered flies did. It follows that this possibility must be ruled out in order for the hypothesis to be plausible, and this answer choice does precisely that.
结论：在群体测验中飞走是因为收到了其他苍蝇释放的信号 削弱：不是因为收到信号，而是单纯跟着同伙一快飞
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