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?

Answer Choices

Correct answer marked below

Some of the non-hyperactive adults in the study had children who suffer from hyperactivity.

The hyperactive adults who participated in the experiment varied in the severity of their symptoms.

The neuropsychologists who designed the experiment were not present when the tests were performed.

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.

Correct

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.

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Comments

ArnavSep 26

Easy D. Medication depresses brain activity, so the low premotor activity could just be a side effect of the treatment, not the cause of the hyperactivity. Classic correlation vs causation trap.

Ayush3h ago

yeah exactly, the meds give an alternate explanation for the low activity. took me a sec to see it but once you catch that it's over

MarceloMay 27

wait why is A wrong? I thought it might mess with the study somehow

ArchanaJun 8

A talks about the non-hyperactive adults' kids, that doesn't really touch whether low premotor activity causes hyperactivity in these adults. it's just irrelevant background

JacobMay 30

ohhh got it, so A doesn't give another cause for the low activity. thanks!

GurpreetMay 12

got tripped up between B and D for a second but B is about severity variation within the hyperactive group, doesn't explain the difference between the two groups at all. D gives the clean alternative explanation

What this question tests

What it tests

Whether you can identify the option that most undermines an argument's conclusion.

Common trap

Choosing an irrelevant objection or one that attacks the premise rather than the reasoning.