LSAT-3-1-15.help feifei-92

victorliao

LSAT-3-I-15.
Baking for winter holidays is tradition that may have a sound medical basis. In midwinter, when days are short, many people suffer from a specific type of seasonal depression caused by lack of sunlight. Carbohydrates, both sugars and starches, boost the brain's levels of serotonin, a neurotransmitter that improve the mood. In this respect, carbon hydrates act on the brain in the same way as some antidepressants, Thus, eating holiday cookies may provide an effective form of self-prescribed medication.

Which one of the following can be properly inferred from the passage?

(A) Seasonal depression is one of the most easily treated forms of depression.
(B) Lack of sunlight lowers the level of serotonin in the brain.
(C) People are more likely to be depressed in midwinter than at other times of the year.
(D) Some antidepressants act by changing the brain's level of serotonin.
(E) Raising the level of neurotransmitters in the brain effectively relieves depression.

The key is D, but what’s wrong with B ?

My reseasoning is as flwg;

1,lack of sunlight(A) ==>depression(B)

2,boost levels of serotonin(C)==>improves the mood(negative B) , so B==>negative C

1+2: A==>B==>negative C,thus lack of sunlight lower the levels of serotonin

What is wrong in the reasoning? Offer your help pls.

bryan0806

In my opinion, improves the mood will not necessarily be negative

B(depression)

victorliao

XDJM pls give me a hand

lawyer_1

1。原文并没有充分必要关系，所以不存在逆否命题的问题。所以你的推理从一开始就是错的。没有出现象IF， UNLESS，ONLY等等词，就不要搞什麽逆否命题。

2。提高levels of serotonin会提高情绪，但情绪低落不一定levels of serotonin降低，因为有可能多种原因影响情绪

温弗雷德

还是有点不明白，是不是说这是因果关系所以不成立阿，否则的话

提高levels of serotonin会提高情绪a->b,情绪低落->levels of serotonin降低不就是b否->a否,那么不就成了逆否命题，不久成立了么

如果是因果关系的话，能不能说一下怎么辨别因果关系还是充分关系啊？谢谢

eggfriedrice006

I think the argument is built around increasing the level of serotonin
would improve mood.  It draws no link between lowering serotonin
and going into depression, thus no link between serotonin and lack of
sunlight.  



Just my 2 cents

singdeath

原文只是说anti－depressant提高brain serotonin，但是没有说depression是因为serotonin level下降。其实原文只给了一个导致depression的原因，那就是lack of sunlight，可没有说lack of sunlight就一定导致brain serotonin level 下降。

原文有两条线索：

导致 depression：lack of sunlight ＝》 depression

治愈depression： increase brain serotonin ＝》 anti－depression

但是原文没有说这两者之间的联系，所以不能从中架桥推出任何结论。所以B不对。

pansimply

我觉得原文显然有误导你之嫌，如果lack of sunlight和brain serotionin level下降没有必然联系的话，原文一开始扯一大堆midwinter的事情干什么？原文的主旨就是说，在midwinter吃cookies是有科学根据的。即吃cookie可以增加糖分和淀粉，而增加糖分和淀粉可以boost brain’s levels of serotonin，这样做的话自然mood就变好了。当然lack of sun并非本文讨论的重点，但是如果不是lack of sunlight可以降低brain serotionin level，进而是mood变差的话，作者第一和第二句话就没有意思了。关键就是在于原文只给了boost mood的原因，没给low mood的原因，而lack of sunlight是brain serotonin level下降的因素之一。

不过，LS分析的还是很对的，这话有点绕，要细细想。

sdcar2010

Must be true type of question.

Carbohydrates boost the brain's levels of serotonin, a neurotransmitter that improve the mood. In this respect, carbohydrates act on the brain in the same way as some antidepressants.

Combine these two sentence:  Some antidepressants boost the brain's level of serotonin.

Isn't that what choice D says?

Inference question is one of the easiest type of CR question. Do not be fooled. Choose only the answer choice that has been mentioned in the passage.

日落归田园

文章的逻辑是这样的：
天冷了，人容易depressed.
吃cookie因为增加serotonin可以使人不抑郁。

但是由此不能说明天冷一定可以减少serotonin。
因为天冷让人depressed的方式可能有很多，不一定是减少serotonon。