PrepTest 154, Section 4, Question 24
People who have experienced a traumatic event but(49 more words not shown)
Which one of the following,(7 more words not shown)
- AMedical conditions sometimes(17 more words not shown)
- BProducing more cortisol(21 more words not shown)
- CPeople experiencing a(14 more words not shown)
- DMany effective treatments(17 more words not shown)
- EExperiencing a traumatic(15 more words not shown)
Reading the argument
Maybe the cortisol difference was there before the trauma.
The observed group matters: these people experienced a traumatic event but did not develop PTSD. Later, when exposed to stress, they tend to produce more cortisol than people who never experienced traumatic events. The author reads that difference as an effect of the trauma. I can see the proposed story, but the comparison alone doesn't establish it.
Could people with higher cortisol responses have been more likely to encounter trauma in the first place? Or could something associated with the traumatic experience, such as a difference in sleep or circumstances, explain the response? Those are guesses about possible explanations, not medical facts. They show why we should ask which came first and whether another factor accounts for the pattern.
What we’re looking for
For a weakener, I'd look for a reason the higher cortisol response needn't be caused by the traumatic event. My first thought is a causal story running the other way, though a different explanation of the observed group could work too. We can accept the measured difference while questioning the author's explanation for it.
Working the answers
- A
Medical conditions sometimes affect cortisol responses in people without trauma. But in which direction, and were such conditions relevant to the groups in this comparison? The answer doesn't tell us. Another possible influence in the comparison group doesn't by itself explain why the particular group that experienced trauma without developing PTSD has higher responses.
- BCorrect
This offers an explanation tied to how that group was selected. Producing more cortisol helps prevent PTSD after trauma. People who already have higher cortisol responses could therefore be especially likely to end up in the group that experienced trauma without developing PTSD.
That group could have higher cortisol responses because those responses helped its members avoid PTSD, not because trauma raised their responses. This differs from my initial idea that cortisol might affect exposure to trauma; the answer concerns who avoids PTSD afterward. It explains the observed pattern without requiring the author's proposed change in cortisol. B needn't prove that trauma never has any effect to weaken this evidence for that effect.
- C
This describes cortisol produced during a traumatic event compared with less severe stress. It doesn't offer an alternative explanation of the later difference the argument uses. If anything, it fits the general idea of a relationship between traumatic stress and greater cortisol production. It doesn't challenge the proposed causal account.
- D
These treatments concern people who have PTSD. The observed group specifically consists of people who did not develop it. What a treatment is designed to do for a different group doesn't explain why this group shows higher cortisol responses or show that trauma didn't cause the difference.
- E
This gives a mechanism supporting the author's explanation: trauma damages a gland, which then produces more cortisol. That would make it easier to understand how trauma could affect production. We're looking for evidence against that causal account, so E goes in the wrong direction.
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