Q24 - People who have experienced a traumatic event

[ohthatpatrick]

Question Type:
Weaken

Stimulus Breakdown:
Conclusion: Having gone through a traumatic event can affect your cortisol level in times of stress.

Evidence: Correlation between having experienced trauma (but not having developed PTSD) and higher levels of cortisol during stress.

Answer Anticipation:
When an author presents a CURIOUS FACT and then provides her own EXPLANATION for / INTERPRETATION of it, there are always two separate possibilities for how to Weaken it:
1. Provide some OTHER WAY of explaining the curious fact.
2. Lower the plausibility of the AUTHOR'S WAY.

So we can go to these answers thinking, "What could be a different way to account for the traumatized but non-PTSD people having higher cortisol levels" or "How could we undermine the plausibility that experiencing trauma can change your cortisol-response to stress, going forward"?

Correct Answer:
B

Answer Choice Analysis:
(A) "Sometimes" is so weak that I pretty much lose interest in this answer, three words in. This answer doesn't provide a different way to explain the curious fact or undermine the plausibility of the author's hypothesis

(B) YES, although this did not grab me instantly. It's trying to offer an alternate storyline that essentially suggests reverse causality. It sounds like they ALREADY had the disposition to produce more cortisol in response to stress, and that's why they ended up not developing PTSD. It's incredibly cloaked, so I would only pick this via process of elimination. It doesn't establish that that the higher cortisol response to stress was already part of their physiology before the traumatic event happened, but that would seem to be a plausible possibility that would offer an explanation for how they could experience trauma but not develop PTSD.

(C) This seems to strengthen the conclusion. It sounds like trauma can affect how much cortisol one makes in response to stress.

(D) "Treatments for PTSD" makes this seem out of scope. The people we're looking at don't have PTSD, so how would this be relevant?

(E) This strengthens the conclusion, by pointing to the causal mechanism by which experiencing trauma could lead to a change in your cortisol response to stress.

Takeaway/Pattern: Well, I found that correct answer very tricky to interpret. I can't think of a similar example in which we're essentially inferring a reverse causality story because the reverse causality story would help explain some other extraneous detail in the stimulus. If the higher cortisol response existed prior to the traumatic event, then it helps to explain why these people didn't get PTSD. We didn't need to explain why they didn't get PTSD, but LSAT is thinking that we'll connect (B) with the other facts we know in order to derive the idea that the higher cortisol response already existed in these people PRIOR to the traumatic event.

#officialexplanation

[BarryM800]

I can see the argument's flaw as "correlation to causation" and (B) points out the possibility of a reversed causation as a way to weaken the argument. But the only way to make sense of (B) is that some people have a disposition to produce more cortisol in the first place - the classic "nature v. nurture" binary debate. Specifically, the conclusion identifies the cause as "experiencing a traumatic event" - nurture/environment, whereas (B) points toward "disposition" - nature/innate.

But what I don't understand is: how do we explain the control group these people (who experienced trauma, but did not develop PTSD) were compared to - "people who have not experienced traumatic events"? If it's disposition, shouldn't it have commensurate prevalence among people, regardless whether they've experienced trauma or not? How do we reconcile this with the premise that clearly dictates that having experienced trauma is a prerequisite/trigger? If it's disposition, presumably it'll manifest itself regardless whether it's the first time the subject is experiencing trauma/stress or the second, third time, etc. Also, did the LSAC use the words "trauma" and "stress" interchangeably here? Thanks!

[Laura Damone]

Ok, so say I'm the researcher. I'm polling people about traumatic events and measuring their cortisol. The evidence is that the trauma survivors without PTSD tend to produce more cortisol in response to stress than the folks in the non-traumatized control group.

In terms of numbers, let's say 1 out of every 100 people has this strong cortisol response thing going on. But that doesn't mean that 1 out of every 100 traumatized-but-not-PTSD-having people has the strong cortisol response. There could be a much higher rate within that second group if the strong cortisol response is causally related to your ability to belong in that group.

Consider this analogy: a sample of any 100 people will give you a certain number who can answer this question correctly. A sample of any 100 LSAT instructors would give you a very different number. That's because the skills necessary to answer the question correctly are causally related to one's ability to become an LSAT instructor and be part of the second group. Make sense?

The disposition doesn't have to be commensurate in prevalence among the two groups if it causally contributes to the ability to be a member of the second group.

So, let's say that 50 out of every 100 traumatized-but-not-PTSD-having people have the strong cortisol response. If I sampled 10 people from the control group and 10 people from the non-control group, I would have 1 in 10 from the control group with the strong cortisol response and 5 in 10 from the non-control group.

Regarding the use of "trauma" and "stress," I don't think they're used interchangeably here. The traumas referred to are traumas in the past, whereas the stress referred to is the stress produced in the present, during the experiment in which cortisol levels are being measured.

Hope this helps!