For most people, the left half of the brain controls linguistic capabi

Question

For most people, the left half of the brain controls linguistic capabilities, but some people have their language centers in the right half. When a language center of the brain is damaged, for example by a stroke, linguistic capabilities are impaired in some way. Therefore, people who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half.

Which of the following is an assumption on which the reasoning in the argument above depends?

(A) No part of a person's brain that is damaged by a stroke ever recovers.

(B) Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.

(C) Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.

(D) If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.

(E) It is impossible to determine which side of the brain contains a person's language centers if the person has not suffered damage to either side of the brain.

keats · Accepted Answer

1988achilles

Conclusion: People who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half.

Option B: 
Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.
 Negated B: 
Impairment of linguistic capabilities  does occur  in people who have not suffered any damage to any language center of the brain.
This does not affect our argument because it says that people who have NOT suffered any damage to any language center of brain are liable to getting their linguistic capabilities impaired. However, the question doesn't differentiate between people who have suffered any damage to language center and people who haven't. Additionally, this does not come close to explaining that people who have suffered a serious stroke on the left side of the brain without suffering such impairment must have their language centers in the right half!

Option D: 
If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.
 Negated D:  
If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages  NONE  of them. So, if it damages NONE in the left side of the brain, you cannot assuredly say that the linguistic capabilities are in the right half of the brain. This breaks the conclusion and is our required assumption.

Hope this helps.

sayantanc2k · Answer

The explanation for B and D is given above by Keats.

The problem with A is the word "no part". If instead it were "the part responsible for linguistic capabilities" then, it could be an assumption. 
Negate A:
Some part of a person's brain that is damaged by a stroke recovers.

The part responsible for linguistic capabilities MAY OR MAY NOT be included in this "some part". Hence the argument does not break down by negating option A.

GMATT73 · Answer

My guess is (D)

2:14

AmritaSarkar89 · Answer

Can anyone please provide a detailed solution for this.
I am kind of totally lost and confused between A B and D

Poorvasha · Answer

Premises :  
Left Half of the brain controls linguistic capabilities, but some people have their language centers in the right half.
 When a language center of the brain is damaged, for example by a stroke, linguistic capabilities are impaired in some way.

Conclusion  : Therefore, people who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half.
 Implication : "such" impairment refers to the linguistic capabilities. Thus, it states that if there is a stroke on the left side of the brain and it results in no impairment on linguistic capabilities, it will imply that the language center of the brain is in the right side because had it been on the left side, it would have been damaged and would have resulted in an impairment of linguistic capabilities. 
Now, we need to find an assumption on which this argument rests.

B vs D.

B  
 
Negation states that impairment of linguistic capabilities occurs in people who have not suffered any damage to any language center of the brain. This may tell that impairment can occur but does not falsify the conclusion that the language center lies in the right side of the brain. Further, impairments did not occur is something that is stated clearly in the argument and conclusion is derived out of that, so we can't really assume that.

D 
 
  Had the language centers been on the left side, the serious stroke would have damaged the language center and complications might have occurred but they didn't , and this means the language center is on the right.  
Negation will also do the job:   If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain does  not  damage at least one of them .

If the language center is not damaged in the left side as well, then it can very much rest in the left side and result in no impairments despite the stroke.

D!

KGump · Answer

RonPurewal ,  GMATNinja ,  GMATNinjaTwo ,

Just want to confirm my understanding for this question.

I could observe a SCOPE SHIFT in the Premise -> conclusion.

Premise talks about "DAMAGE to language center impacting Lingusitic capabilities" whereas Conclusion talks about "Stroke in Left side of brain w/o Impairment must have LANGUAGE CENTERS in right"

Assumption MUST Connect " stroke in left side of brain " to "DAMAGE in language center".

IS this understanding correct ?

Also, Why is option A incorrect.

Had option A stated " part of the brain responsible for linguistic capabilities never recovers" . Would it then be correct ?

Thankyou

GMATNinjaTwo · Answer

KGump , your analysis seems logical and supports the correct choice (D).

As for option (A), we don't care whether the patient has recovered from the damage. The conclusion says, "...without suffering any such impairment". This implies that those people NEVER suffered such impairment. People who suffered from the damage and then recovered would not be included in this group.

I hope that helps!

JAIN09 · Answer

GMATNinjaTwo

i have a doubt with regard to option B,although option D is correct

the assumptions i could think of are:
1.if there is a damage to left part of brain,then the linguistic center must be affected. otherwise in-spite of the damage to left side of the brain,there will be no language impairment(linked to option D)
2.only brain and no other part of the body controls the linguistic capabilities .if not true ,then inspite of the damage to left part of brain will not ensure that the language centers are in right side of the brain(linked to option B)

GMATNinjaTwo · Answer

Yes, if some people's language centers are NOT in the brain, then the argument would not hold. While the passage does not specifically rule out this possibility, it certainly seems unlikely given the information in the passage: most people's language centers are in the left half of their brains and SOME people's language centers are in the right half of their brains. This seems to suggest that the language centers are always in the brain, on one side or the other.

Regardless, choice (B) does not tell us whether language centers can exist outside of the brain and thus doesn't address your second assumption.

Choice (B) implies that the ONLY cause of impairment of linguistic capabilities is damage to a language center of the brain. But surely there are other ways to impair a person's linguistic capabilities (i.e. damage to the mouth, voice box, spinal cord, etc.).

Whether there are other ways to impair a person's linguistic capabilities has no bearing on the argument. We are only concerned with what happens when people suffer a stroke.

I hope that helps clear up your doubt!

DharLog · Answer

For most people, the left half of the brain controls linguistic capabilities, but some people have their language centers in the right half. When a language center of the brain is damaged, for example by a stroke, linguistic capabilities are impaired in some way. Therefore, people who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half.

Which of the following is an assumption on which the reasoning in the argument above depends?
------------
A. No part of a person's brain that is damaged by a stroke ever recovers. 
B. Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.
C. Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.
D. If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.
E. It is impossible to determine which side of the brain contains a personâ€™s language centers if the person has not suffered damage to either side of the brain.
-------------

Maybe the first or one of a few questions that I saw, where all options except from the right one (D) are simply irrelevant.
Only D gives us a link.
No need to do any negations.

atrayee345 · Answer

D. This is the assumption made in the argument. If we negate this statement and say that a serious stroke affecting the side of brain which consists the linguistic centre doesn’t damage it then the whole conclusion would be wrong. So, it must be assumed that stroke would damage the part of brain. Hence, D is the answer.

gmatconqueror2018 · Answer

Got this question wrong on my practice test. Tricky prompt. Always find the conclusion. Stroke on LS yet no impairments means LC on right side. Why? LC have linguistic capabilties and are on one side of the brain. Choice D says if there are LC's on left side and stroke affecting that side of brain happens, then LC will be damaged. Same side = effect. If not effect, LC on other side of brain. I was running out of time and had to guess unfortunately. Good question.

meenakshimiyer · Answer

A. This statement holds no relevance to the conclusion made in the argument.
B. Here we are talking about the impairment caused by damage to language centers of the brain and we have derived a conclusion base on that only. Linguistic impairment caused by other reasons than damage to linguistic centers is not the concern.
C. We are not supposed to compare impairment caused by strokes or any other damage.
D. This is the assumption made in the argument. If we negate this statement and say that a serious stroke affecting the side of brain which consists the linguistic centre doesn’t damage it then the whole conclusion would be wrong. So, it must be assumed that stroke would damage the part of brain. Hence, D is the answer. 
E. The conclusion is about determining whether the linguistic centre is on left side or right side and not about whether only damages can determine the centre or not.

Pas4867 · Answer

The answer is D. The conclusion suffers from a generalization error, the passage states that if someone suffers a serious left side stroke and does not suffer language impairment, they must have the language centers on the right side of their brain. It does not, however, account for the possibility that the stroke might simply have not caused any damage to the language centers. The assumption in option D closes that gap by stating if someone has a serious stroke in the left side of the brain and if there are language centers there, they will be damaged.

sayan640 · Answer

VeritasKarishma  
Please explain this question.
I was confused between B and D . Ended up choosing B.

mykrasovski · Answer

Can anyone please explain why (D) is better than (A)? Option (A) negated attacks the conclusion, while (D) seems to be irrelevant. I have spent way too much time on this problem and yet I am unable to understand it. Thank you in advance.

GMATNinja · Answer

Sorry for our slowness on this,  mykrasovski ! This might be too late to be useful, but just in case it helps somebody out there...

The author concludes that "people who have suffered a serious stroke on the left side of the brain without suffering any   impairment must have their language centers in the right half."

He/she bases this conclusion on the following reasoning:

People either have language centers in the right or left half of their brain 
 When a linguistic center is damaged, linguistic capabilities are impaired.

We need to find an assumption  on which the argument depends  -- in other words, the correct answer choice MUST be true in order for the conclusion to follow from the evidence presented.

Take a look at (D):
 
The author's conclusion centers on people who have had a serious stroke on the left side of the brain (which does not sound fun). These people suffered this stroke, but their linguistic capabilities were not impaired -- yay! From this, the author concludes that these people's language centers must not have been in the left side of the brain at all. Instead, those centers must be in the right side of the brain.

But wait -- what does a "serious stroke" in half of the brain really mean? Would a stroke like that actually damage  everything  in that side of the brain? Or could some brain functions exist in that side of the brain, but survive the stroke without being impaired?

To conclude that the language centers MUST be in the right side of the brain, the author has to assume that a serious, left-side stroke would  absolutely, without a doubt  damage some language centers if they were indeed located in the left side of the brain. Otherwise, it is entirely possible for a person with left-side language centers to have a serious left-side stroke without any linguistic impairment -- maybe that stroke just happened to miss all of the language centers in the left side.

(D) MUST be true in order for the author's conclusion to hold, so (D) is an assumption on which the argument depends.

Hmm. (A) gives us information about  recovering  from a stroke. If you look back at the passage, the author doesn't specify whether the impairment caused by a stroke is  permanent  -- he/she just says that "when a language center of the brain is damaged, for example by a stroke, linguistic capabilities are impaired in some way." Whether that damage is temporary or permanent does not impact the author's argument at all.

Because the information in (A) doesn't HAVE to be true for the author's argument to hold, it is not an assumption on which the argument depends. Eliminate (A).

I hope that helps!

jabhatta2 · Answer

GMATNinja   VeritasKarishma   GMATNinja Two  mira93

I thought D weakened the argument actually because of the pluralism in the word " language centers " (implying more than one language center on the left side of the brain itself)

Now reading option D entirely, it suggests that at least 1 language center will be affected ( at-least one  implies 1 could be affected or 2 could be affected or all of them on the left hand side of the brain could be affected)

Making up a scenario :

Imagine there are 2 language centers on the left side of the brain and only only 1 out of the 2 was affected by the stroke ( at least-one , implies 1 or more - i am choosing 1 for my scenario)

Hence there is still one language center remaining on the left side of the brain in my scenario.

Hence there is another reason why language by the subject is NOT impaired (because out of the 2 language centers on the left side of the brain, only 1 are affected in my scenario and 1 is un-affected).

Thus the fact that the patient's language is un-impaired maybe because of the un-affected language center on the left hand side of the brain itself

Thank you !

KarishmaB · Answer

Premises:
Most people have language centres (plural) in left, some have in right.
When a language center (even one) of the brain is damaged, linguistic capabilities are impaired in some way.

Conclusion: People who have suffered a serious stroke on the left side of the brain without suffering any language impairment must have their language centers in the right half.

We are looking for an assumption, a missing necessary premise. Note here that the premises say that when any one of the  language centres is damaged ,  linguistic capabilities are impaired  in some way, but the conclusion says that people who suffer a  serious stroke  on the left side would see  language impairment  if language centre was on left side. So the assumption is that a  stroke  on the left side would impair  language centres  if they are present on the left side.

(A) No part of a person's brain that is damaged by a stroke ever recovers.

Recovery is out of scope.

(B) Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.

We don't know what can or cannot happen when there is no damage to language centres.

(C) Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.

We are not assuming that strokes are the most damaging.

(D) If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.

Correct. We are assuming that a serious stroke to a side will damage the language centres if they are present there.

(E) It is impossible to determine which side of the brain contains a person's language centers if the person has not suffered damage to either side of the brain.

There may be other ways to determine where the language centres are.

For most people, the left half of the brain controls linguistic capabi

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For most people, the left half of the brain controls linguistic capabi

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