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My answer is D

The argument says that 'when it comes to general intelligence, as measured by IQ scores, nurture wins out' over nature

We have to choose the answer choice that makes this conclusion hard to believe

(A) Some of the most profound thinkers in history with the highest IQs have begun to speak at a later age than most of their peers.
- irrelevant, eliminate
- tells us nothing about which of the two (nature or nurture) contributes more to IQ

(B) Since a link between folate and brain development was established several decades ago, general human intelligence, as measured by IQ scores, has not risen by any significant amount.
- tempting
- but 'brain development' is not equivalent to IQ
- perhaps folates help with some aspect of brain development that is unrelated to IQ

(C) The Baby Genius series of products has been heavily criticized by a number of leading researchers in cognitive development research.
- irrelevant, eliminate

(D) In cases in which identical twins have been adopted at birth by different families, the twins have always had IQ scores that fell within 5 points of each other, when one standard deviation on the IQ scale is 15 points.
- perfect
- shows that IQ is not affected by nurture

(E) Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.
- irrelevant, eliminate


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Quote:
In the nature-versus-nurture debate, when it comes to general intelligence, as measured by IQ scores, nurture wins out. Otherwise, there would be no need for expectant mothers to take prenatal vitamins with added folate to aid with brain development in the growing fetus, and early-learning advancement products such as the Baby Genius series of musical toys would find no market, not to mention that parents would have no need to read to their children or encourage their children to read to develop language skills ahead of their peers.

Which of the following, if true, casts the most doubt on the argument presented in the passage?

We are given that in nature vs nurture - nurture wins in the case of general intelligence and the measurement criterion is the IQ scores.
And then we are given the importance of more supporting evidences (Vitamins, Baby Genius products series & Parental involvement in children skills development) in favor of nurturing, in the process of IQ development.

Since we have to weaken the argument we will find some positive points for nature or negative points for nurture. Or may be that nurture is dependent on nature for increasing the IQ.


Quote:
(A) Some of the most profound thinkers in history with the highest IQs have begun to speak at a later age than most of their peers.

But how is speaking related to high IQ scores?
More importantly we do not know the reason behind high IQ scores. We can eliminate it.

Quote:
(B) Since a link between folate and brain development was established several decades ago, general human intelligence, as measured by IQ scores, has not risen by any significant amount.

Even though GI has not risen in decades, it may be possible that its level are high enough, for a IQ scores, which support the nurturing rather than nature. Also, we are not told that the Vitamins, Genius products etc were not present in the last decades. we can eliminate it.

Quote:
(C) The Baby Genius series of products has been heavily criticized by a number of leading researchers in cognitive development research.

The products may be criticized, but they may still have positive effects on the GI development process. Eliminate it.

Quote:
(D) In cases in which identical twins have been adopted at birth by different families, the twins have always had IQ scores that fell within 5 points of each other, when one standard deviation on the IQ scale is 15 points.

Ok the score difference in twins is always less than the standard deviation. The keyword to notice here is ALWAYS, which in combination with scores results points to the fact that nature has somewhat upper hand (though not clearly mentioned). We can consider this option.

Quote:
(E) Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.

If we were given that voice recognition is responsible for GI development. We could have considered this option. But as of now we can eliminate it. Also we have a better answer above.

IMO D is the best answer
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In the nature-versus-nurture debate, when it comes to general intelligence, as measured by IQ scores, nurture wins out. Otherwise, there would be no need for expectant mothers to take prenatal vitamins with added folate to aid with brain development in the growing fetus, and early-learning advancement products such as the Baby Genius series of musical toys would find no market, not to mention that parents would have no need to read to their children or encourage their children to read to develop language skills ahead of their peers.

Which of the following, if true, casts the most doubt on the argument presented in the passage?

Pre-think:
Cause: nurture Effect: different general intelligence (IQ scores)
Evidence: Markets for prenatal vitamins, early-learning advancement products, etc. exist.

Question type: WEAKEN
We need to find evidence showing that nurture does not win out in the debate.

(A) Some of the most profound thinkers in history with the highest IQs have begun to speak at a later age than most of their peers.
Not clear whether nature or nurture wins out in the debate.

(B) Since a link between folate and brain development was established several decades ago, general human intelligence, as measured by IQ scores, has not risen by any significant amount.
OFS

(C) The Baby Genius series of products has been heavily criticized by a number of leading researchers in cognitive development research.
OFS

(D) In cases in which identical twins have been adopted at birth by different families, the twins have always had IQ scores that fell within 5 points of each other, when one standard deviation on the IQ scale is 15 points.
Cause: different families / different methods of nurturing --> No effect: identical twins with not very different IQ scores.


(E) Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.
Support "nature" a little but not really weaken "nurture"

Correct answer: D
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OFFICIAL EXPLANATION

I cannot believe we are five days in already. If the last CR question is any indication, then this one ought to go well for about two-thirds of those responding. This is a straight-up weaken the argument question:

Quote:
Which of the following, if true, casts the most doubt on the argument presented in the passage?
In any strengthen/weaken question, be sure to stick to the exact argument put forth. Associative thoughts will often lead you down an incorrect path, and answer choices are carefully designed to play into such reasoning.

Quote:
In the nature-versus-nurture debate, when it comes to general intelligence, as measured by IQ scores, nurture wins out. Otherwise, there would be no need for expectant mothers to take prenatal vitamins with added folate to aid with brain development in the growing fetus, and early-learning advancement products such as the Baby Genius series of musical toys would find no market, not to mention that parents would have no need to read to their children or encourage their children to read to develop language skills ahead of their peers.
First off, on a side note, I know the GMAT™ would not touch a topic as controversial as IQ scores with a ten-foot pole. But this is just for fun, just for us, an exercise for us to practice CR-style passages and questions to better prepare for the real thing.

Sentence one is the argument. A claim is put forth that, based on IQ score information regarding general intelligence, nurture wins out [in the nature-versus-nurture debate]. Sometimes this happens in passages. The argument or conclusion comes first, with premises, the why behind the what, to follow.

Sentence two is lengthy, but it merely lists reasons to support the argument of the previous sentence, relying on negation to make the point: 1) mothers-to-be take prenatal vitamins; 2) there is a market for early-learning advancement products; 3) parents read to their children; and 4) parents encourage their children to read.

There are plenty of holes to spot here, but remember, do not lose sight of the argument itself, just as it is presented in the first sentence. We need to find a flaw with the argument, not with any of the premises.

Quote:
(A) Some of the most profound thinkers in history with the highest IQs have begun to speak at a later age than most of their peers.
A nod to Einstein, anyone? I caution people about vague, non-committal language such as some in many of my CR posts. It is a common trap that plays on associative reasoning. (There are exceptions in which you want a some answer, but most of the time, you should tread carefully.) Here, if some profound thinkers have been late talkers, what about other profound thinkers? Some could refer to just two, and those two might be exceptions to a general trend. Most importantly, ask yourself whether this information compellingly works against the notion that nurture wins out, regarding intelligence. To be honest, you should not be able, with this information, to make any headway on either side of the debate. I call this a red light answer.

Quote:
(B) Since a link between folate and brain development was established several decades ago, general human intelligence, as measured by IQ scores, has not risen by any significant amount.
The problem here is that just because such a link was found, we cannot say that expectant mothers have been taking prenatal vitamins with added folate. The passage does not provide any information to that effect. (Be careful not to read between the lines.) The argument could still hold that nurture would be more important than nature, particularly if the mothers who took prenatal vitamins ended up producing children with higher intelligence, on average, than that of the general population. Red light.

Quote:
(C) The Baby Genius series of products has been heavily criticized by a number of leading researchers in cognitive development research.
This appeal to authority has no bearing on the argument. It latches onto a premise about early-learning advancement products and creates an issue out of nothing more than a detail. If leading researchers go against a product for a particular reason, then that product might be substandard for that reason, but we could not then extrapolate anything about the larger concern at hand. Red light.

Quote:
(D) In cases in which identical twins have been adopted at birth by different families, the twins have always had IQ scores that fell within 5 points of each other, when one standard deviation on the IQ scale is 15 points.
Notice the absolute language in always. This type of language is either overreaching or used to almost over-qualify an answer choice. (Significantly works in a similar capacity and often appears in correct answers, as though GMAC™ wants to make the correct answer less debatable.) The idea here is that no matter what, identical twins end up roughly the same in terms of intelligence, using the very metric that the argument, flawed or not, is based upon. Sure, we have no idea how these twins may have been raised, but the very fact that they have been separated and raised in whichever way, yet still come out with roughly the same intelligence, makes a strong case for a natural (non-nurtured) or innate intelligence. This is just what we are looking for to weaken the argument that nurture wins out. Green light.

Quote:
(E) Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.
Studies is another iteration of some. How many studies? Three? Five? And what does this natural linguistic capability have to do with the argument presented, one that leans on IQ scores to make a point? Because the answer is long-winded, it may be harder to follow. If that proves to be the case for you with any answer choice, then just yellow light that option in the first pass and move on. Work from a place of comfort and get rid of what you either know is incorrect or have a very strong feeling about to that end. You can reassess if you need to on a second pass. In this case, though, once we break it down, we should realize that it does not affect the argument at all, so it cannot be the answer to the question being asked. Red light.

I hope that helps. Again, do not be afraid to look back at the passage and reread that argument or conclusion as often as is necessary to make heads or tails of a given answer choice. Lose track of that exact argument, and CR will never prove to be anything more than a guessing game.

- Andrew

Hey AndrewN
Great explanation. Have a small question. What if (E) says "Studies show prove that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born."
Will that be considered a right answer? Reason - the innate ability of the unborn (to recognize parents' voice blah blah) proves nature is superior else the parents would have to encourage their children to read to develop language skills ahead of their peers.

Please can you point the flaw in my thinking?
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Hi AndrewN

i have a question standard deviation of 15 tells us that 68% people lie within 15 units of mean on either side .

So it does not tell us mean avg is less than 5 units or more
So how we can say which one is better nurture or nature

Thanks
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carouselambra

Hey AndrewN
Great explanation. Have a small question. What if (E) says "Studies show prove that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born."
Will that be considered a right answer? Reason - the innate ability of the unborn (to recognize parents' voice blah blah) proves nature is superior else the parents would have to encourage their children to read to develop language skills ahead of their peers.

Please can you point the flaw in my thinking?
Thank you, carouselambra, for the kind words. It is funny, I thought this question might provoke a cooler response from the test audience than the previous (what I deemed safer) CR question, about scurvy, but what do I know about the general audience? Anyway, I like your proposed change to (E) so much that I wish I had thought of it myself. An absolute in prove would make that answer an even better trap. After all, we can place confidence in such a definitive outcome, right? The problem is that the argument is based on general intelligence, as measured by IQ scores. Unless babies were taking IQ tests, this new information in (E) would have no bearing on that argument, proof or no.

I hope that helps.

- Andrew
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Deepakjhamb
Hi AndrewN

i have a question standard deviation of 15 tells us that 68% people lie within 15 units of mean on either side .

So it does not tell us mean avg is less than 5 units or more
So how we can say which one is better nurture or nature

Thanks
Hello, Deepakjhamb. I did not refer to a normal distribution or a mean in answer choice (D). The fact that one standard deviation consists of 15 points, and identical twins always fall within a narrow range of each other, well within one standard deviation, allows us to appreciate that their identical nature seems to affect their general intelligence, as measured by IQ scores, more than how they may have been raised. Consider the following examples:

Twin A: IQ 120; Twin B: IQ 115-125
Twin C: IQ 100; Twin D: IQ 95-105
Twin E: IQ 145; Twin F: IQ 140-150

No matter where one twin seems to fall on the IQ scale, the other is closely paired. That is the logic behind answer choice (D); if nurture won out, then we would expect more pronounced IQ differences across some of the separated twins, at least.

I hope that helps.

- Andrew
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IanStewart
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Quote:
(E) Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.
Studies is another iteration of some. How many studies? Three? Five?

I don't think it's right to characterize things this way -- if a GMAT CR answer choice says "studies show that X is true", I think a test taker should read that to mean "X is true", unless information elsewhere gives reason to doubt the validity of the studies. The same would be true of a sentence like that in a question stem. If that weren't the case, we wouldn't really be able to trust a lot of the factual information we're presented with, because a lot of that information comes from studies. Of course it's possible to see a question about a single study that draws a conclusion, where we want to weaken the conclusion or argument, and in that case we might be looking for a methodological flaw in the study. But when a GMAT CR sentence suggests there's some kind of research consensus around a factual question, I don't think I've ever seen an official question where we're meant to treat that consensus as if it were suspect.

As for the question, I'd echo Andrew's comments about the content of the question; the GMAT would never contend IQ test scores measure "general intelligence" (if they measure anything, it's a very narrow conception of "intelligence", at least as people view "intelligence" today, but IQ scores are controversial for many reasons). And I think the right answer here really casts doubt on the conclusion more than on the argument itself, which is a bit of a different thing (if we cast doubt on the conclusion, we're finding a reason, perhaps some additional information like what we find in answer D, to think the conclusion isn't true; if we're casting doubt on an argument, we're finding an issue with the logic that leads from the evidence to the conclusion). The main issue with the argument itself is that it relies on the behaviour of parents to derive its conclusion. When the question tells us that the question of nature vs nurture is an open debate, one presumably not settled among specialist researchers, why would we think parents have any special knowledge about it? Just as we wouldn't rely on polling data to settle a question about quantum mechanics, we probably shouldn't rely on the behaviour of non-experts to settle a nature/nurture question.

Answer D does of course cast doubt on the conclusion, since if it were true (it's not, but if it were) it suggests that the circumstances of one's upbringing, which is what 'nurture' means in this context, have little eventual effect on IQ. The actual real world studies of this question are a bit more mixed; they demonstrate that both nature and nurture play some role.
All valid points, IanStewart, and I appreciate your taking the time to articulate everything. Concerning the first point, I will only say that there is more to the analysis than the snippet quoted above, of course, and we agree on the overall waywardness of (E). I hold all analyses posted by Experts to a higher standard than those by general members, and my own most of all. I welcome constructive criticism so that I might refine my own reasoning and subsequent treatment of the material in my posts.

- Andrew
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