Aphasia, an impairment of the capacity to use

Question

Official Guide for GMAT Verbal Review, 2nd Edition

Practice Question 
Question No.: 21
Page: 123  
Aphasia, an impairment of the capacity to use language, often occurs when a stroke damages the left half of the brain. Many people with stroke-related aphasia recover at least some capacity to use language within a year. One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Which of the following, if true, most strongly supports the explanation?

(A) In a study of local brain activity in people performing a language task, people with stroke related aphasia showed higher activity levels in the right half of the brain than people who did not have aphasia.

(B) A blow to the head injuring the left half of the brain can result in impairment of the capacity to use language indistinguishable from that produced by a stroke.

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.

(D) A stroke that damages the left half of the brain often causes physical impairments of the right side of the body that lessen over time.

(E) Studies of numerous people with aphasia have indicated that the functions that govern language production and those that govern language comprehension are located in separate areas of the brain.

Gian · Accepted Answer

IMO A

I'll directly come to choices A and C.

Suppose, in a normal healthy person, Left Part controls 90% of language tasks and Right part controls 10% tasks. The argument mentions:

" One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center,
develops its latent language capabilities to compensate for the damage to the left side. "

Normal People (without Aphasia)

------------- Brain ------------------
************** | ************
************** | *************
 *** Left Part | Right Part ****
****** 90% ****** 10% ****

People affected with Aphasia

------------- Brain ------------------
************** | ************
************** | *************
 *** Left Part | Right Part ****
****** 50% ****** 40% ****(tries to compensate for the loss incurred in the left part because of aphasia)

Choice A -> Study shows exactly what I've shown above that aphasia affected people have higher levels in Right part of the brain than normal people.

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities
normally controlled by the right half of the brain.

We have to support the explanation that the right part of brain is indeed responsible for compensating for the lost capacity in the left part. Does this choice mentions which part of the brain is responsible for recovering lost capacity? NO It merely states that the recovering capacity doesn't affect the existing capacities controlled by the right part of the brain.

Does it make sense ?

MartyTargetTestPrep · Answer

Correctly answering this question requires clearly defining the difference between choice (A) and choice (C), one of which is correct and the other of which is a tempting trap.

To see why one is correct and the other is not, let's first consider the passage and the question.

Aphasia, an impairment of the capacity to use language, often occurs when a stroke damages the left half of the brain. Many people with stroke-related aphasia recover at least some capacity to use language within a year. One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Which of the following, if true, most strongly supports the explanation?

Which of the following, if true, most strongly supports the explanation?

The question asks us which choice most strongly supports the explanation. So, to correctly answer the question we have first to identify the explanation.

Explanation: The right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Now, let's consider choices (A) and (C), starting with choice (C).

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.

We need something that supports the explanation that the right side took over the language function. This choice is tempting, because it seems to indicate that the right side of the brain does not become impaired. So, a test-taker may decide that the fact that this choice seems to indicate that the right side does not become impaired means that this choice indicates that the right side took over the handling of language related tasks.

The truth is, however, that this choice gives us no information that supports the explanation.

It does not indicate that the stroke did not damage the right side of the brain, only that right side based capacities were not lost DURING THE PERIOD OF RECOVERY from the stroke.

It does not indicate that the right side took on new functions, i.e., changed. Rather it tells us what did not change.

In other words, choice (C) tell us only what DID NOT HAPPEN during the period of recovery, which information clearly does not help to support the explanation that the right side took over.

Now let's consider choice (A).

(A) In a study of local brain activity in people performing a language task, people with stroke related aphasia showed higher activity levels in the right half of the brain than people who did not have aphasia.

This choice provides information that indicates that the right sides of the brains of people who have experienced stroke related aphasia took over the handling of language language related tasks. How? By showing that there is a DIFFERENCE between the right sides of the brains of these people and the right sides of the brains of people who have not experienced stroke related aphasia. The right sides of the brains of people who have experienced stroke related aphasia show more activity than is shown by the right sides of the brains of other people when people from these two groups are engaged in language related activities.

Does this information necessarily mean the the right sides of brains of people who have experienced stroke related aphasia are now performing language related functions? No. However, the fact that the right sides of the brains of these particular people, the ones who have experienced stroke related aphasia, show more activity than those of other people when these particular people are engaged in language related activities specifically tends to indicate that something language related is going on in the right sides of the brains of people who have experienced stroke related aphasia that is not going on in the right sides of other people's brains.

So, (A) provides additional support for the explanation.

TGC · Answer

I fully understand why the OA.

However, I did not understand the explanation OG gave while rejecting option (C).

(C). This provides no evidence about whether it is the right half of the brain’s developing its latent
language capabilities that alleviates aphasia. It could be these patients experience no impairment
of capacities controlled by the right half of the brain because the right half of the brain is
completely uninvolved in stroke patients’ recovery of language-use capability.

IMO, (C) states

Among people infected with APHASIA,RECOVERING LOST CAPACITY doesn't lead to IMPAIRMENT OF THOSE CAPACITIES , and these CAPACITIES are normally controlled by RIGHT HALF of the BRAIN.

And why it cannot be an answer which states that RECOVERING doesn't imply IMPAIRMENT OF THOSE CAP, and these CAP. controlled by RHB.
Implies that RIGHT HALF plays an important ROLE in recovering !!!

Plz advise !

rahulsehgal · Answer

Even when I was attempting this question, I ended up selecting 'C' as the answer. But the overall answer is 'A'.

rahulsehgal · Answer

Thank you Gian

+1 Kudo. It makes perfect sense now. A is the correct answer and NOT C.

vietmoi999 · Answer

it is too hard and I want to follow this problem.

TGC · Answer

Hi e-gmat,

Aphasia, an impairment of the capacity to use language, often occurs when a stroke damages the left half of the brain. Many people with stroke-related aphasia recover at least some capacity to use language within a year. One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Which of the following, if true, most strongly supports the explanation?

My Analysis:
 Premise:Stroke damages left part=>Aphasia. 
 MANY recover some capacity within a year.

Conclusion: And the recovery is possible is due to RIGHT SIDE of the BRAIN.

Assumptions:
 Left side of the brain doesn't heal automatically over time and regains some capacity to use language. Hence, only RIGHT side of the BRAIN is responsible for the recovery.

Since I have query in (A) and (C), so will discuss the same.

(A) In a study of local brain activity in people performing a language task, people with stroke related aphasia showed higher activity levels in the right half of the brain than people who did not have aphasia.
Doesn't it go too far in saying that

HIGHER ACTIVITY LEVELS while performing language task => strengthen conclusion.

But the HIGHER ACTIVITY LEVELS can be for something else. For instance, thinking something else while performing LANGUAGE TASK.

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.

I don't understand the meaning of the option itself, let alone the elimination of this option.

Please suggest !

egmat · Answer

Dear Student, Thank you for your post.

As per the question, a possible explanation for the stated recovery is that the right side of the brain develops its dormant capabilities to compensate for the damage to the left-side. So as per this explanation, the right side is now doing some work that it wasn’t doing earlier. This work is done to compensate for the lack of certain activities in the left part of the brain. Now, our job in this question is to strengthen the explanation given above. I can see that in your analysis of choice A, you have correctly understood the link between higher activity levels in the right part of the brain and its engagement in the stated area. However, the consideration raised by you that HIGHER ACTIVITY LEVELS can be for something else. For instance, thinking something else while performing LANGUAGE TASK makes me think that you may be looking for a choice that concretely proves/ “very” strongly indicates that the proposed explanation is correct. However, the role of a strengthener is to just increase our belief in the conclusion and not necessarily prove the same, a job that this choice does fully well and you have already made the relevant link between the higher activity levels and the proposed explanation. Now, coming to choice C that says: Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain. Choice C states that the process of recovery in stroke-related aphasia patients does not cause any damage to the abilities usually controlled by the right half of the brain. Now do you think this choice sheds any information on what leads to the process of recovery in the first place? Thanks, Neeti.

TGC · Answer

Hi e-gmat,

Agree with your explanation.

Just wanted to know the meaning what (C) wants to say. On the other hand, I know this choice is irrelevant to conclusion.

vnigam21 · Answer

Aphasia, an impairment of the capacity to use language, often occurs when a stroke damages the left half of the brain. Many people with stroke-related aphasia recover at least some capacity to use language within a year. One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Which of the following, if true, most strongly supports the explanation?

(A) In a study of local brain activity in people performing a language task, people with stroke related aphasia showed higher activity levels in the right half of the brain than people who did not have aphasia.

(B) A blow to the head injuring the left half of the brain can result in impairment of the capacity to use language indistinguishable from that produced by a stroke.

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.

(D) A stroke that damages the left half of the brain often causes physical impairments of the right side of the body that lessen over time.

(E) Studies of numerous people with aphasia have indicated that the functions that govern language production and those that govern language comprehension are located in separate areas of the brain.

I am clear with the understanding of option A. My Understanding of Option C : (C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain. Lets negate this option. Negation - Among people with stroke-related aphasia, recovering lost capacity to use language does lead to any impairment of those capacities normally controlled by the right half of the brain. Lets revisit the proposed explanation again, Proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center , develops its latent language capabilities to compensate for the damage to the left side. What does the negation says?? Among people with stroke-related aphasia (often occurs when a stroke damages the left half of the brain ), recovering lost capacity does lead to any impairment of those capacities normally controlled by the right half of the brain.

Probus · Answer

Hi vnigam21

Here are my two cents for this questions

Well whats that the argumnet concluded

Aphasia, an impairment of the capacity to use language, often occurs when a stroke damages the left half of the brain. Many people with stroke-related aphasia recover at least some capacity to use language within a year. One proposed explanation for such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side.

Which of the following, if true, most strongly supports the explanation?

Hey whenever there is language impairment due to stroke that damages the left side of the brain which is major language center ,Right side of brain kicks in to compensate for this impairment.

Any information that shows Right side of brain is capable of doing job or in the past has done in such cases can strengthen our argument. 
It would be noteworthy to think how we can weaken the argument and reverse of that will strengthen it. 
Possible weakners
Right hand side does not have any such thing or can never be stimulated to support language.

or
Damage of major language center causes right side of brain to loose the capabilities of language canter.

or 
Right hand side of brain which is capable of recovering from language impairment to function partly as language center needs to first draw information from the major language center which is left side of brain.

Now if you reverse the above weakeners, we could see possible strengtheners in our argument.

Now Option C:
Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.

What this option says is hey when people with the aphasia , regain partly the capacity to use language, this does not impact the other functions controlled by right side of brain. 
All you could get is when they recover the capacity to use language , this recovery does not impact any other functions that are normally controlled right side of brain.
Well something else might have helped to recover the capacity to use language, and in this recovery process the functions that controlled by right side are not impaired.
 
Can we say that right side of brain did play a role in part in recovering language capacity or does this statement make you believe that people with aphasia recover lost capacity of language due to this side of brain. No .

So we can reject this answer choice.

Does this help!!

Probus

KanishkM · Answer

Out of A, C and E

(A) In a study of local brain activity in people performing a language task, people with stroke related aphasia showed higher activity levels in the right half of the brain than people who did not have aphasia.
This supports the claim that right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side. -> Correct Answer

(C) Among people with stroke-related aphasia, recovering lost capacity to use language does not lead to any impairment of those capacities normally controlled by the right half of the brain.
But why are we even concerned about what functions, were initially controlled by the right half of the brain.
The argument is talking about the aftereffect that "such recoveries is that the right side of the brain, which is not usually the major language center, develops its latent language capabilities to compensate for the damage to the left side."

(E) Studies of numerous people with aphasia have indicated that the functions that govern language production and those that govern language comprehension are located in separate areas of the brain.
here we dont know which side supports which function -> Eliminate

Burhanuddin · Answer

I am no expert, but that is what i have seen most of the GMAT questions trick you.
For this question, the question stem is most important part.
 ' Which of the following, if true, most strongly supports the explanation? ' 
The question is asking us to find an option that supports the given info. option c, however, does not address the argument, it gives additional information and this information is not completely necessary to jump to the conclusion that the right side of the brain adapts to the problem.
  C gone, A in.

TheiBanker · Answer

Here's how I interpreted C:

Suppose multiple skills reside in different halves of the brain predominantly. Lets say, driving is controlled by left half vs playing soccer is controlled by right half.
Now a person gets a stroke and his left half of brain is gone. He cant of course cant drive properly now. Over next 1 year, he tries to learn driving again and picks up skills partially. Maybe he is no F1 racer now but he still can drive for a km or two now.

C says, doing this i.e. trying to recover the lost skills doesnt causes the skills already developed and controlled by the right half to be impacted. i.e. The person can still play soccer with same finesse pre and post stroke.

C doesn't explains how this person developed new capabilities for the lost skills using RIGHT HALF of the brain. A explains that!

VerbalBot · Answer

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Aphasia, an impairment of the capacity to use

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