PT28 S1 Q23

[thegrayman]

Can someone explain the answer to this one to me? I am having a difficult time seeing why A is the credited response. I initially picked C and then picked it again when I reviewed my test, eliminating A rather quickly both times.



TIA

[Atlas LSAT Teacher]

This is a tricky answer to spot - I definitely skimmed right past (A) myself.

The conclusion of the argument is that one's mood is caused by frontal lobe activity. Why? Because those who are sad showed less left frontal activity and those who were happy showed greater activity. We're looking for the one answer that does not weaken this argument. Looking at the core of this argument, I see a gap related to causation - perhaps the mood causes the activity and not vice versa. But, since 4 answers are going to weaken the argument, it would be hard to predict all the ways this will happen.

On first glance, (A) looks like a weakener - it's a version of what I predicted: the mood (by way of the drug) causes the brain activity. However, it says that depression increases left lobe activity, and the argument says that sad folks have less left lobe activity. One thing that is confusing is that it seems to contradict the premise the sad folks have less left lobe activity, but in fact there is no contradiction. Depressed folks could generally show X though a drug that can be used to treat depression might have a different effect. Furthermore, it's rare that an LSAT weakener simply disputes a premise - we're looking to weaken the connection between the premises and conclusion.

(B) weakens gives another reason for the decreased left lobe activity.
(C) gives a reason we should be wary of a connection between mood and brain activity. If they were connected as the argument suggests, they would both have to shift - we couldn't have one be stable and the other keep changing.
(D) gives another reason for both the mood and brain activity.
(E) gives another reason for increased brain activity in happy folks, thus leaving the sad folks with relatively less brain activity.

Does that clear it up?

Apologies to all the psych majors for having depression = sadness and a mood!

[Edit for clarity]

[thegrayman]

That helps a ton! Thank you very much, I was lost on that one.