PrepTest 105, Section 1, Question 4
In an experiment testing whether hyperactivity is due(69 more words not shown)
Which one of the following,(10 more words not shown)
- ASome of the(11 more words not shown)
- BThe hyperactive adults(12 more words not shown)
- CThe neuropsychologists who(11 more words not shown)
- DAll of the(35 more words not shown)
- EThe test was(33 more words not shown)
Reading the argument
What if the lower brain activity is an effect of hyperactivity rather than a cause?
The experiment found a difference between the two groups: the hyperactive adults had less activity in the premotor cortex. Accepting that observation doesn't tell us which way the explanation runs.
The experimenters conclude that reduced activity in that region causes hyperactivity. My first response is to ask whether hyperactivity could instead lead to the reduced activity. Either story could fit the association they found. We need more than the fact that the two occur together to choose between those stories.
What we’re looking for
We're asked to weaken the conclusion. I'd look for evidence that challenges the proposed causal direction or otherwise explains why the groups had different brain activity. We don't have to deny the measured difference; we have to question what it establishes about the cause of hyperactivity.
Working the answers
- A
This concerns hyperactivity in the participants' children. It doesn't tell us why the hyperactive adults had reduced activity in the premotor cortex or whether that reduction caused their hyperactivity. A family relationship, by itself, doesn't challenge the proposed explanation.
- B
Different levels of symptom severity can coexist with a common cause. Perhaps reduced activity contributes to hyperactivity while other factors influence its severity. This answer doesn't compare severity with the brain measurements, so it supplies no conflict with the experimenters' conclusion.
- C
The people who designed a test needn't personally attend its administration for the results to be useful. Someone else could carry out the procedure properly. Without a reason to think their absence affected the test, this gives us no specific challenge to the inference.
- DCorrect
This gives us another explanation for the measured difference: medication. Every hyperactive participant had received a drug known to reduce activity in some brain regions, while none of the other participants had received it. The drug could be responsible for the lower activity we observed.
That's a more specific route than my initial prediction. Hyperactivity leads to treatment, and treatment could produce the brain-activity difference. In that case, the difference wouldn't establish that reduced premotor activity caused the hyperactivity. D doesn't prove the medication affected this particular region, but it introduces a relevant difference between the groups that makes the experimenters' explanation less secure.
- E
This explains why the researchers studied adults rather than children. It doesn't explain away the difference between the two adult groups or show that the adult measurements were unreliable. A reason for limiting the participants isn't itself a reason to reject the proposed causal relationship in the people tested.
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