In an experiment testing whether hyperactivity is due to

Question

In an experiment testing whether hyperactivity is due to a brain abnormality, the brain activity of 25 hyperactive adults was compared to the brain activity of 25 adults who were not hyperactive. The tests revealed that the hyperactive adults had much less brain activity in the premotor cortex, a region of the brain believed to control action, than did the non-hyperactive adults. The experimenters concluded that diminished activity in the premotor cortex is one cause of hyperactivity.

Which one of the following, if true, most undermines the conclusion drawn by the experimenters?

(A) Some of the non-hyperactive adults in the study had children who suffer from hyperactivity.
(B) The hyperactive adults who participated in the experiment varied in the severity of their symptoms.
(C) The neuropsychologists who designed the experiment were not present when the tests were performed.
(D) All of the hyperactive adults in the study had been treated for hyperactivity with a medication that is known to depress activity in some regions of the brain, while none of the non-hyperactive adults had been so treated.
(E) The test was performed only on adults because even though the method by which the test measured brain activity is harmless to adults, it does require the use of radiation, which could be harmful to children.

Paras96 · Answer

To undermine the conclusion drawn by the experimenters that diminished activity in the premotor cortex is one cause of hyperactivity, we need to find information that suggests an alternative explanation or confounding factor for the observed difference in brain activity between hyperactive and non-hyperactive adults.

Option (D) provides a potential alternative explanation. It states that all of the hyperactive adults in the study had been treated for hyperactivity with a medication known to depress activity in some regions of the brain, while none of the non-hyperactive adults had been treated with this medication. This suggests that the observed differences in brain activity between the two groups could be due to the effects of the medication rather than being a cause of hyperactivity. Therefore, option (D) undermines the conclusion drawn by the experimenters.

Option (A) mentions that some of the non-hyperactive adults had children who suffer from hyperactivity, but this information does not directly address the cause of hyperactivity in the adults themselves.

Option (B) mentions the variation in the severity of symptoms among hyperactive adults, but this alone doesn't necessarily undermine the conclusion about the premotor cortex's role in hyperactivity.

Option (C) discusses the presence of neuropsychologists during the test, but this doesn't directly relate to the cause of hyperactivity.

Option (E) discusses the use of radiation and the exclusion of children from the test, but it doesn't provide an alternative explanation for the observed brain activity differences in adults.

A_Nishith · Answer

To undermine the conclusion drawn by the experimenters that diminished activity in the premotor cortex is one cause of hyperactivity, we need to find information that suggests an alternative explanation or confounding factor for the observed difference in brain activity between hyperactive and non-hyperactive adults.

Option (D) provides a potential alternative explanation. It states that all of the hyperactive adults in the study had been treated for hyperactivity with a medication known to depress activity in some regions of the brain, while none of the non-hyperactive adults had been treated with this medication. This suggests that the observed differences in brain activity between the two groups could be due to the effects of the medication rather than being a cause of hyperactivity. Therefore, option (D) undermines the conclusion drawn by the experimenters.

Answer: D

yc168 · Answer

OE for reference:

Overview:   This passage recounts an experiment and the conclusion drawn by the experimenters. The experiment showed that, compared to nonhyperactive adults, hyperactive adults had much less brain activity in a region of the brain believed to control action. The experimenters concluded that this abnormality in the brains of hyperactive adults is one cause of hyperactivity.

The question asks what would undermine this conclusion. The only thing the experiment firmly establishes is a correlation between hyperactivity and diminished activity in a certain region of the brain. The experimenters' conclusion is one possible explanation for that correlation. So anything that points to an alternative explanation of the observed correlation would undermine the experimenters' conclusion.

The Correct Answer:

D  (D) tells us that the differences in brain activity found in the experiment could well have been caused by the medication taken by the hyperactive adults but not by the nonhyperactive adults. So (D) points to an explanation of the experimental results that gives us a clear alternative to the conclusion that the experimenters reached.

The Incorrect Answer Choices:

A  The experimenters' conclusion was based on tests performed on hyperactive and nonhyperactive adults. Information about the children of any of these adults has no bearing on what can be concluded from those tests.

B  Variation in the severity of symptoms of hyperactivity would be expected in any random sample of hyperactive people. (B) gives us no reason to think that the experimenters had any difficulty in clearly distinguishing between adults who were hyperactive and those who were not. So (B) does nothing to challenge the experiment and thus does nothing to undermine the conclusion based on it.

C  As long as an experiment was competently carried out, it makes no difference to the outcome whether the people who actually designed the experiment were present or not. (C) provides no reason to think that the experiment was not competently carried out. Thus (C) does nothing to undermine the conclusion based on the outcome of that experiment.

E  (E) explains why the experimental subjects were all adults. It does not call into question the reliability of the results obtained by the experiment. Nor does it challenge the conclusion based on those results.

In an experiment testing whether hyperactivity is due to

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In an experiment testing whether hyperactivity is due to

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