KAPLAN OFFICIAL EXPLANATION

Here we have a cause-and-effect argument presented in the context of a study. The trauma of the vets must have caused the loss of hippocampi cell mass, the doctors conclude, because those with stress symptoms had smaller hippocampi than those without the symptoms. We're looking for something that would weaken the argument, and a classic way of attacking cause-and-effect is illustrated by (C), which points out that the cause and effect could actually be working in reverse— it could be that the symptoms are the result of the small hippocampi, rather than vice versa. This should remind you of Nietzsche's Cornaro example presented a few pages back. (C) it is.

An 800 test taker knows all the potential weaknesses of a causal argument. When confronted with the proposition that X caused Y, he considers the possibility that Ymay have in fact caused X, that some third factor Z caused both X and Y; or that the two things are merely correlated and thus not causally related at all.

(A) The argument concerns the effects of "violent or life-threatening" events. The death of a close relative is traumatic, of course, but it isn't
"violent or life-threatening," as those terms are used here. So (A) is irrelevant.

(B) and (E) do the opposite of what we're looking for here. The very fact that (B) asserts the similarity among all the veterans studied tends to support, rather than weaken, the study's findings. And (E), if anything, strengthens the argument by cementing the connection between trauma and tiny hippocampi.

An 800 test taker keeps her eye on the ball at all times, and does not carelessly choose a strengthener when asked for a weakener, or vice versa.

(D) omits the main issue—the connection between trauma and hippocampi damage—and hence cannot have any effect on the reasoning.
_________________

Which of the following, if true, would most seriously weaken the researchers' conclusion drawn above?

Conclusion: Hippocampi had lost cell mass as a result of trauma.

We need to weaken this conclusion. Maybe an alternative cause will do that for us. Option C does exactly that.
(C) Some individuals are born with Hippocampi whose volume is smaller than average, and this reduced volume makes them more susceptible to post traumatic stress symptoms.

Option A seems to be a contender but C does the best to weaken the conclusion.

Studies of trauma victims suggest that shock brought on by violent or life-threatening situations causes damage to the hippocampi, structures in the brain that play a crucial role in learning and memory. Researchers found that in combat veterans suffering from posttraumatic stress symptoms, which include nightmares and vivid flashbacks, the hippocampi were eight percent smaller in volume than in combat veterans who suffered no such symptoms. The researchers concluded that the hippocampi had lost cell mass as a result of trauma.

Which of the following, if true, would most seriously weaken the researchers' conclusion drawn above?


(A) In another study, subjects who had experienced the death of a close relative were found to have no reduction in the volume of their hippocampi when compared to those whose close relatives were all still living. Incorrect

this choice is not related with posttraumatic stress symptoms, it partially against argument

(B) In the study, the traumatized veterans were compared with other veterans of similar background, body size, and other characteristics that might have a bearing on brain size. Irrelevant

(C) Some individuals are born with hippocampi whose volume is smaller than average, and this reduced volume makes them more susceptible to posttraumatic stress symptoms. Correct

it against argument, smaller hippocampi is the reason for posttraumatic stress symptoms

(D) Combat veterans who experience post-traumatic stress symptoms perform significantly worse on tests of verbal memory compared with veterans who suffer no such symptoms. Incorrect

perform on tests of verbal is irrelevant

(E) Further study revealed that veterans who had seen more intense combat and had more severe post-traumatic symptoms exhibited even greater reduction in the volume of their hippocampi. Incorrect

support argument

Answer : C



A weakening question !
Let's try to break it down.

Stimulus:
Studies show trauma (violent or life-threatening situations)causes damage to hippocampi.
In combat veterans going through posttraumatic symptoms, hippocampi was smaller.
Conclusion: Hippocampi lost mass due to trauma.

For weakening, we need to attack the stimulus and try to disapprove it.
How can we attack?
1.We can say veterans (subjects) were not actually representative of the study, maybe, they were not actually having trauma.
2.Maybe the cause for reduction in size was something else.

Let's go through the options to see if we can find some other cause as well.


First let-off, "Another study" and they experienced death of close relative, but in original stimulus, we are only concerned with violent or life-threatening situations or post-traumatic stress.
It is kind of irrelevant, It does not strengthen/weaken.
Let's chuck it !


This only adds weight to study by saying that subjects were similar. It helps to strengthen the study's findings.


The conclusion in stimulus stated, trauma reduces the size. This option says, some individuals were already born with smaller hippocampi and that makes them more susceptible to stress symptoms. So, it reverses the causal connection in full.
It helps to attack the conclusion directly.
This fits in perfectly for answer.


Combat Veterans suffered stress -> Hippocampi Reduces -> Learning and Memory Affected -> Worse on tests on memory.
This strengthens the conclusion by following the same line of reasoning mentioned in stimulus.
Let's Move on.


This again strengthens the relationship that more violent or life-threatening situation, more reduction.
Time to chuck this as well.

An easy formula that can be used, especially for the weakening questions is:
1. If Cause has lead to Effect : Prove that there was an alternate cause
2. If Cause will lead to Effect : Prove that effect may not happen
3. Reverse cause and effect

The above question falls under #3 category.
Let's closely examine (C)

Some individuals are born with hippocampi whose volume is smaller than average, and this reduced volume makes them more susceptible to posttraumatic stress symptoms.
This reverses the cause and effect action and weakens the argument. If we prove that some individuals are born with a size of hippocampi which is smaller than the average, then the conclusion is weakened.

Conclusion: hippocampi had lost cell mass as a result of trauma.

Pre-thinking: Can we have another reason for smaller "hippocampi".

Which of the following, if true, would most seriously weaken the researchers' conclusion drawn above?

(A) In another study, subjects who had experienced the death of a close relative were found to have no reduction in the volume of their hippocampi when compared to those whose close relatives were all still living. -> We have an example, but we don't the reason. It is not weakening the conclusion.

(B) In the study, the traumatized veterans were compared with other veterans of similar background, body size, and other characteristics that might have a bearing on brain size. -> No reference with conclusion.

(C) Some individuals are born with hippocampi whose volume is smaller than average, and this reduced volume makes them more susceptible to posttraumatic stress symptoms. -> We have another reason for smaller "hippocampi". Let's keep it.

(D) Combat veterans who experience post-traumatic stress symptoms perform significantly worse on tests of verbal memory compared with veterans who suffer no such symptoms. -> It is strengthening the conclusion.

(E) Further study revealed that veterans who had seen more intense combat and had more severe post-traumatic symptoms exhibited even greater reduction in the volume of their hippocampi. -> It is strengthening the conclusion.

So, I think C.

Studies of trauma victims suggest that shock brought on by violent or life-threatening situations causes damage to the hippocampi, structures in the brain that play a crucial role in learning and memory. Researchers found that in combat veterans suffering from posttraumatic stress symptoms, which include nightmares and vivid flashbacks, the hippocampi were eight percent smaller in volume than in combat veterans who suffered no such symptoms. The researchers concluded that the hippocampi had lost cell mass as a result of trauma.

Which of the following, if true, would most seriously weaken the researchers' conclusion drawn above?

Conclusion: The hippocampi had lost cell mass as a result of trauma.
Trauma-->Smaller hippocampi

(A) In another study, subjects who had experienced the death of a close relative were found to have no reduction in the volume of their hippocampi when compared to those whose close relatives were all still living.
Irrelevant

(B) In the study, the traumatized veterans were compared with other veterans of similar background, body size, and other characteristics that might have a bearing on brain size.
This option gives the detail on how the study was done.

(C) Some individuals are born with hippocampi whose volume is smaller than average, and this reduced volume makes them more susceptible to posttraumatic stress symptoms.
Smaller hippocampi-->Trauma
This choice says that the stated relationship is reversed.
Smaller hippocampi causes trauma

(D) Combat veterans who experience post-traumatic stress symptoms perform significantly worse on tests of verbal memory compared with veterans who suffer no such symptoms.
This is a strengthener

(E) Further study revealed that veterans who had seen more intense combat and had more severe post-traumatic symptoms exhibited even greater reduction in the volume of their hippocampi.
This is a strengthener

Choice C is the answer

After some pre-thinking, we must come up with a question "What if it was the other way around? What if there are people who were seen to have a small hippocampi size and then were proved to lead to greater trauma when exposed to a traumatic situation?"

Answer option C shows that it is the other way around. Some people with smaller hippocampi exhibited more traumatic symptoms upon experiencing trauma.