Answer : CQuote:
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 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.
Quote:
(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.
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 !
Quote:
(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 only adds weight to study by saying that subjects were similar. It helps to strengthen the study's findings.
Quote:
(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.
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.
Quote:
(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.
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.
Quote:
(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 again strengthens the relationship that more violent or life-threatening situation, more reduction.
Time to chuck this as well.