In a study examining the neural pathway linking auditory perception

Question

In a study examining the neural pathway linking auditory perception to motor skills, brain scans of study participants who were tone-deaf-those unable to differentiate between or produce sounds of various pitches-revealed many fewer fibers on the arcuate fasciculus, the pathway connecting the frontal and temporal lobes, than there were in a control group of non-tone-deaf people. In 90 percent of the tone-deaf participants, researchers could not detect the superior branch of the arcuate fasciculus. The researchers concluded that they had found the anatomical cause of tone deafness.

Which of the following would, if true, indicate a major flaw in the researchers' reasoning?

A. Although 17 percent of the population self-identifies as tone-deaf, not all of them are clinically tone-deaf.

B. An inability to produce sounds that match a particular tone induces fibers of the arcuate fasciculus to atrophy and die.

C. Many of the participants in the control group had perfect pitch, the ability to recognize and reproduce any given tone.

D. Fibers in the arcuate fasciculus of the tone-deaf participants exhibited more activity than did those of the control group.

E. People who are tone-deaf perform similarly on tests of gross-motor skills to people who are not tone-deaf.

GMATNinja · Accepted Answer

The researchers conclude that they have found the anatomical cause of tone deafness: tone-deaf people have "many fewer fibers on the arcuate fasciculus" than do non-tone-deaf people. In fact, 90% of tone-deaf people don't seem to have a "superior branch of the arcuate fasciculus."

We're looking for a major flaw in the researcher's reasoning. Here's (D):

(D) gives us a bit more information about the nature of the difference between tone-deaf and non-tone-deaf people. Tone-deaf folks have "many" fewer fibers, but those fibers exhibit "more activity."

Notice that we don't know  how much  more activity -- it could be that these fibers are just SLIGHTLY more active, meaning that "many fewer" fibers in tone-deaf people are still processing way less info than those in non-tone-deaf people. Additionally, (D) doesn't tell us exactly  where  these more-active fibers are located. Perhaps the issue is that these people don't have a "superior branch," and increased activity in other fibers won't make up for this deficit.

Overall, (D) is perfectly compatible with the researchers' reasoning. There is still a notable anatomical difference between the two groups, and (D) doesn't give us a reason to doubt the researchers' argument.

Compare that with (B):

This tells us that the researchers are  way off . Instead of the difference in fibers causing tone deafness, tone-deafness causes the difference in fibers.

This really blows a hole in the researchers' reasoning. (D) is out, and (B) is the correct answer.

I hope that helps!

tejasbadani · Answer

B is right because the passage is clearly a causal passage. A causes B. In this case, tone deafness is caused by low concentration of the fibres. Option B clearly states that, there is a possibility where low concentration of fibres is caused by tone deafness. Which reverses the causal situation. Which is a major flaw in the argument.

sayan640 · Answer

I got it correct. The reasoning is :- If some external factor i.e absence of required sound makes fibres to deteriorate and die then we can't say that there was an anatomical defect present among the deaf. May be there was no anatomical mismatch at all among the two groups in the beginning and the conclusion derived by the scientists is totally flawed.
 
B is the correct answer.
 KarishmaB  , Can you kindly check my reasoning ?

Posted from my mobile device

Michelle777 · Answer

Why would one choose B I???m confused between ans choice A and B

mollyweasley · Answer

GMATNinja   bb  could you explain why choice D is incorrect?

GMATkid1997 · Answer

B. this is a classic gmat answer. The stimulus says a Cause -> Effect.

The AC weakens this by reversing this relationship

sarthak1701 · Answer

It is the classic cause-and-effect CR question. The argument fallaciously concludes that the lack of that particular neural pathway is what causes tone-deafness, however, it might be possible that tone-deafness itself causes that neural pathway to atrophy and eventually disappear. The argument correctly identifies the 2 elements of the cause and effect (the neural pathway and tone-deafness) but incorrectly identifies the relationship between them. Ans B

Aboyhasnoname · Answer

The Question is SO Tough! What is Atrophy and this fasiculus. I was unable to understand in my mock...However....What is still bothering me is that the line..could not detect the superior branch of arcuate fasiculus.....

What I understood that there is another branch of this A fasiculus that is absent. and this is why people are tone deaf.

In a study examining the neural pathway linking auditory perception to motor skills, brain scans of study participants who were tone-deaf-those unable to differentiate between or produce sounds of various pitches-revealed many fewer fibers on the arcuate fasciculus, the pathway connecting the frontal and temporal lobes, than there were in a control group of non-tone-deaf people.
  In 90 percent of the tone-deaf participants, researchers could not detect the superior branch of the arcuate fasciculus.  The researchers concluded that they had found the anatomical cause of tone deafness.

Which of the following would, if true, indicate a major flaw in the researchers' reasoning?

A. Although 17 percent of the population self-identifies as tone-deaf, not all of them are clinically tone-deaf.
Out of scope

B. An inability to produce sounds that match a particular tone induces fibers of the arcuate fasciculus to atrophy and die.
Okay this makes sense, but what I am confused here is that the researchers never said is that its the absence of superior branch not the fibers on that... 
Just a little explaination here would help. Thanks

D. Fibers in the arcuate fasciculus of the tone-deaf participants exhibited more activity than did those of the control group.
If I forget about the branch thing, than while this could be a weakener not shure if thats the best weakener....

Aboyhasnoname · Answer

Arguement: 
A - Absence of Superior Branch of arcuate fasciculus
B - Tone deafness 
Conclusion - Absence of superior branch 
of arcuate fasciculus causes Tone deafness

A Causes B 
Weakener 
B causes A - Tone deafness causes absence of superior branch of of arcuate fasciculus

Option B says. 
Tone deafness causes absence fibres. (Which are fewer in tone deaf study group.)

How are we equation superior branch of arcuate fasciculus to fibres on arcuate fasciculus?? 
Thats my doubt.

GMATNinja · Answer

Before answering that, note that you don't really need to equate the two to see that (B) represents a major flaw in the researchers' reasoning, since we know that there is a negative correlation between fibers and tone deafness. The researchers would argue that a lack of fibers causes tone deafness, while (B) suggests that tone deafness causes a lack of fibers. The stuff about the superior branch is just extra evidence.

That said, we're told that the arcuate fasciculus is a neural   pathway   connecting the frontal and temporal lobes. It's not hard to imagine a main branch of that pathway with various little branches and connections stemming off the main branch, sort of like a highway. And if that pathway/highway system consists of fibers, then it's reasonable to infer that its branches (including the superior branch) consist of fibers as well.

I hope that helps!

Dream009 · Answer

A. Although 17 percent of the population self-identifies as tone-deaf, not all of them are clinically tone-deaf.

I think this was the correct, since if they do not have any clinical tone deafness and still that fibre is missing - so it cannot be the cause something else would be

B. An inability to produce sounds that match a particular tone induces fibers of the arcuate fasciculus to atrophy and die. 
 I couldn't understand this when I was doing it undertime and this seemed irrelevant.

C. Many of the participants in the control group had perfect pitch, the ability to recognize and reproduce any given tone.  
 We don't care about control group

D. Fibers in the arcuate fasciculus of the tone-deaf participants exhibited more activity than did those of the control group. 
 We are concerned with presence v/s non presence not activity level

E. People who are tone-deaf perform similarly on tests of gross-motor skills to people who are not tone-deaf. 
 If they perform similarly then that cannot be the cause of distinctiion - but we are never told gross motor skill and fiber are connected

What am I missing?

Dream009 · Answer

GMATNinja 
 KarishmaB  - please help. I am really struggling

KarishmaB · Answer

In cause effect arguments (A causes B), keep in mind that a valid weakener is 'B causes A'. That is what we have here. Observations: Brain scans of study participants who were tone-deaf revealed many fewer fibers on the arcuate fasciculus than in a control group. In 90 percent of the tone-deaf participants, researchers could not detect the superior branch of the arcuate fasciculus. Researchers' Hypothesis: They had found the anatomical cause of tone deafness. (Fewer fibers on the arcuate fasciculus cause tone deafness - A causes B) A. Although 17 percent of the population self-identifies as tone-deaf, not all of them are clinically tone-deaf. Distinction between self identification and clinical tone deafness is out of scope. We are just told that the study had tone-deaf people - whether clinical or self identified, we don't know. B. An inability to produce sounds that match a particular tone induces fibers of the arcuate fasciculus to atrophy and die. This tells us that tone deafness causes the fibers of the arcuate fasciculus to atrophy and die i.e. tone deafness causes fewer fibers. Hence this option says 'B causes A' and is the answer. C. Many of the participants in the control group had perfect pitch, the ability to recognize and reproduce any given tone. We know that people in control group were not tone deaf. Perfect pitch or less than perfect doesn't matter. D. Fibers in the arcuate fasciculus of the tone-deaf participants exhibited more activity than did those of the control group. The discussion is the number of fibers, not their level of activity. We don't know how their level of activity impacts ability to produce various pitches. Irrelevant. E. People who are tone-deaf perform similarly on tests of gross-motor skills to people who are not tone-deaf. The researchers concluded about the link between 'fewer fibers' and 'tone deafness.' That is what we have to weaken. Connect between gross motor skills and tone deafness is irrelevant. Answer (B) Discussion on Weaken Questions: https://youtu.be/EhZ8FKkfy0k

KarishmaB · Answer

Option B is the reversal of cause-effect as explained in my comment above.

GMATNinja · Answer

Choice (A) is about the general population, not the study participants in particular. We're told that those participants were tone deaf, and that's all that matters. If, hypothetically, the study involved asking random people on the street if they were tone deaf and trusting their responses without any sort of testing or verification, then (A) might be more interesting. But that requires making a major assumptions not stated in the passage. And even if we make those assumptions, we'd have no way of knowing how significantly this impacted the study. If, for example, almost all of the 17 percent are in fact clinically tone deaf, then the effect on the study would likely be insignificant. (B) is a better option, as explained in the following posts: https://gmatclub.com/forum/in-a-study-e ... l#p3402746 https://gmatclub.com/forum/in-a-study-e ... l#p3615188

In a study examining the neural pathway linking auditory perception

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