Normally, the pineal gland governs a person's sleep-wake cycle by secreting melatonin in response to the daily cycle of light and darkness as detected by the eye. Nonetheless, many people who are totally blind due to lesions in the visual cortex of the brain easily maintain a 24-hour sleep-wake cycle. So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex.

For purposes of evaluating the argument it would be most useful to establish which of the following?

(A) Whether melatonin supplements help people who have difficulty maintaining a 24-hour sleep cycle to establish such a pattern

(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness

(C) Whether melatonin is the only substance secreted by the pineal gland

(D) Whether most people who do not have a 24-hour sleep-wake cycle nevertheless have a cycle of consistent duration

(E) Whether there are any people with normal vision whose melatonin levels respond abnormally to periods of light and darkness

Thank you expert for posting.
normally I prethink an assmption for evaluate question though in some easy cases, the prethinking process happens naturally without effort . When the prethinking process dose not happen naturally, we have to take effort to prethink.

when it is hard to prethink an assumption, we have a hard question. of course there are many other factore which make the cr questions hard.

I can not prethink assumption and I have to go to answer choices and take a very long time to get to correct answer.

how do you do this question to finish it in 2,3 minutes. ? do you prethink an assumption.

pls, I want to know what is the assumption you prethink. I do not want to know what is an assumption for the correct answer. it is easy to find an assumption for the correct answer after you find the correct answer. it is also easy to explain the correct answer. But the problem is how do you prethink an assumption and what is an assumption prethought for this type of question. all of us know that the prethough assumption maybe is not the assumption on which the weakener/strengthener is based but the prethinking process is alway helpful.

what did you prethink before you look at the answer choices for this question. How do you prethink for this question. that is what we want to learn from you. what do you do before you look at the answer choices.

we need to know the SPECIFIC goal which we need to find in the answer choices. what we need to find in the answer choices must be spedific for us to be successful.if we identify only the general goal such as "information which increase this conclusion" we can not succeed.

pls help.
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1. Normal-Pineal gland releases melatonin in response to day and night
2. But wait, Blind people with lesions still mantain a consistent sleep cycle too
Conclusion: The pathway to get dark/light info from the eye skips the visual cortex
Key inferences/implications: 1. meltaonin regulates our sleep pattern in both blind and 'can see' people 2. Even in 'can see' people the pineal gland's pathway to producing melatonin skips the visual cortex

Pre-think- I see one possible and likely problem in this already, what if there was another way for the body to produce that melatonin consistently other than from light and darkness information?

Another important thing to notice that would have practical applications. None of the answer choices mention anything about a visual cortex, so even more justification not to not look to strengthen that link to any other part of the problem. Let's just focus on melatonin production then

A Meltaonin regulates sleep patterns. It's a fact in the prompt. We shouldn't doubt this which is what A is trying to do
B
C All we know about meltaonin is it regulates our sleep and is the only relevant hormone in the prompt. We could care less about other hormones OOS
D Prompt only talks about 24 hour sleep cycle OOS
E What does a spike or lack of meltanin have to do with anything? I'm not a scientist and this prompt doesn't tell me what an abundance or dearth of melatonin will do to my sleep cycle. We just want to know why a certain consistency of meltonin helps keep a regulated sleep pattern in both blind and 'can see' people

POE B

Let's look at B
(B) Whether the melatonin levels of most totally
blind people who successfully maintain a
24-hour sleep-wake cycle change in response to
changes in exposure to light and darkness

This question would answer the pre-think I had. If it is true that, say blind people can get means to produce meltatonin without detecting light, somehow regularly,they can still mantain a sleep cycle. Also agrees with prompt and constricts it to blind people and 24 hour sleep cycle. Doesn't make the errors of other answer choices.
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My problem is the same as already mentioned above. I am pretty good at explaining answers I already know. Problem lies in the pre-thinking.

In this case, I have to support that the neural pathway by which the pineal gland receives information from the eye probably doesn't pass through the visual cortex.

My first answer was A. Because if I said the melatonin supplements helped people, it would mean that the pineal gland and melatonin did their job without the visual cortex or bypassing the visual cortex.

I am wrong somewhere in my thinking. I am convinced by option B. That is not a problem. Kindly help

Situation-

Daily cycle of ligth and darkness is detected by eye.Pineal gland maintains sleep wake cycle.The pineal gland secrets melatonin in response to this cycle of detection to maintain sleep wake cycle!
BUT blind people ( due to lesions in the visual cortex) also maintain the same rhythm or sleep wake cycle.

Conclusion-

So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex.

Evaluation-

The author is not sure about the mechanism.He has given us a PROBABLE explanation. We need to help him confirm or reject his conclusion.
We need to make it more probable or less probable.
We need to a help him find a piece of information that will help to find whether the neural pathway passes through visual cortex .

POE

(A) Whether melatonin supplements help people who have difficulty maintaining a 24-hour sleep cycle to establish such a pattern

We do not need to comfirm whether melatonin helps to maintain a 24 hour sleep wake cycle.We already know for a fact that melatonin does affect the sleep wake cycle.
Also the main point of the argument is about people who maintain normal sleep cycle.


(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness

A yes answer to the above option will help confirm that pineal gland does respond to light and darkness cycles NOT detected by the eye.Hence, the neural pathway does not pass through the visual cortex.
A no answer to the above option will help confirm that the neural pathway does pass through the visual cortex.


(C) Whether melatonin is the only substance secreted by the pineal gland

That is besides the point. It may release many other substances but we are only interested in the melatonin and the associated mechanism.

(D) Whether most people who do not have a 24-hour sleep-wake cycle nevertheless have a cycle of consistent duration

The duration of the cycle is not so much of an issue as is the mechanism behind the sleep wake cycle.

(E) Whether there are any people with normal vision whose melatonin levels respond abnormally to periods of light and darkness

This does no help us understand the mechanism or the pathway behind the sleep cycle.The reasons for abnormal levels may be varied.
This option just tells us that melatonin levels change with light and darkness but does not answer whether the neural pathway passes through the visual cortex.


Hope the above helps!

I donot mind Kudos.

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My reasoning was different so somebody pl approve :

Pineal grand => melatonin => visual cortex via. neural pathway => eye

normal cycle

No if in blind people with defect in visual cortex still getting the info of 24 hr sleep wake cycle then obviously visual cortex doesn't play any role. and cycle should be


Pineal grand => melatonin => eye

right?
But here the assumption is there is no other alternative thing for blind people working to make that happen.


(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness

If this is true then yes, we can say neural pathway is not via visual cortex.
if not, then there is some other process and neural pathway could be via visual cortex

Depending on the stage of Critical Reasoning, it is good to try to think like a test maker.

by P.O.E. process

a) Changes of m also change S-W cycle ------> This option doesn't tackle the connection urging for an explanation (L-D) captured by P.G. OUT!

c) P.G. produces element "X" ----> who guarantees this element is an alternate explanation for S-W cycle regulation? OUT!

d) Duration of S/W Cycle vary with/out eye -----> This option doesn't tackle the connection urging for an explanation (L-D) captured by P.G. OUT!

e) One element with eye varies melatonin abnormally regardless Light and Dark ---------> One single element can't be representative of a whole hypothesis This test could be helpful only if constantly we get this results from other individuals and if blind individuals also present the same result OUT!

The three reasons for why choosing B

1st) The main point of the hypothesis, which is the connection between Light-Darkness and P.G., is being fully assessed by the test. From the diagram below it is easy to see why this is the best option.

2nd) The test is being conducted in a controlled group (blind people), which would dismantle the hypothesis if proved the other way round. (the melatonin doesn't change in the abscence of an eye)

3rd) Differently from e), the question considers many individuals and not only one to be tested

Here is the logic.

Hope it helps

This is an OG question.
Argument says that blind people who have lesions in visual cortex also maintain sleep-wake cycle.
Then what must be reason for this. Only B is questioning the melatonin level change in blind people.
So answer B.

Kudos are welcome.
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Hi Experts,
Can you help me to understand pre-thinking and underlying assumption to evaluate answer choices?
I tend to make statements in arguments causal to help bridge gap between premises and conclusion in order to find assumptions while attempting evaluate Q type.
For eg:
cause: variations in response to daily light as detected by eye
effect: PG gland governs person's sleep cycle by secreting M.
Final conclusion: NP by which PG receives information from eye does not pass through VC.
Supporting premise for conclusion: People who are totally blind due to defect in VC maintain 24 hours sleep cycle. This premise counters general principle in first sentence.
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Normally, the pineal gland governs a person's sleep-wake cycle by secreting melatonin in response to the daily cycle of light and darkness as detected by the eye. Nonetheless, many people who are totally blind due to lesions in the visual cortex of the brain easily maintain a 24-hour sleep-wake cycle. So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex.

What are we looking for - So, due to the lesions in the visual cortex , blind person can't detect the light , but still maintains the sleep and wake cycle. It is a fact that pineal gland secretes something to maintain the sleep/wake cycle. So we are thinking that pineal gland must have received the info of light/darkness by a way not via visual cortex (which is blocked in blind folks). So can we looking for details which can give us answer as yes / no.

For purposes of evaluating the argument it would be most useful to establish which of the following?

(A) Whether melatonin supplements help people who have difficulty maintaining a 24-hour sleep cycle to establish such a pattern
-- Irrelevant. We are not talking about supplements.

(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness
-- If we say Yes - We can infer yes there must a way to pineal gland which doesn't go via visual cortex, which is blocked.
-- If we say No - We can infer there is no way. The only way is by pineal gland.This is the reason melatonin levels are not getting changed.There must be something else, which is controlling the sleep-wake cycle.
-- So this is the answer.

(C) Whether melatonin is the only substance secreted by the pineal gland
-- Even if there are other substances, there is no relation shown with sleep-wake cycle, so Irrelevant.

(D) Whether most people who do not have a 24-hour sleep-wake cycle nevertheless have a cycle of consistent duration
-- Irrelevant.

(E) Whether there are any people with normal vision whose melatonin levels respond abnormally to periods of light and darkness
-- There can be multiple reasons of this issue. Out of scope.