#23 - Further evidence of a connection between brain

[eober]

Here the stimulus saying that good-natured participants exhibit greater left lobe activity and question stem is asking which answer choice does NOT weaken the argument. In this case, how does answer choice E weaken the argument. It is stating that social interaction (not seen in clinically depressed) stimulates the left lobe activity. Isn't this answer choice supporting the argument instead of weakening it?

[Nikki Siclunov]

Hi,

The argument is structured as follows:

Premise: Clinical depression correlates with decreased left lobe activity, whereas lack of depression correlates with increased left lobe activity.

Conclusion: Frontal lobe activity affects one's general disposition

Frontal lobe activity (cause) General disposition (effect)

This is a typical Causal flaw in the reasoning: correlations merely support the presence of causal relationships; they do not prove that such relationships actually exist. To weaken this argument, we can come up with a third, independent factor (X), which causes both of the correlated phenomena to occur simultaneously. Answer choice (D) does that, and is therefore incorrect.

Alternatively, we can come up with evidence suggesting that the causal relationship is reversed. Answer choice (E) suggests that it may be: if social interactions of the type not engaged in by clinically depressed people stimulate left lobe activity, then the increased left lobe activity of those not suffering from clinical depression may be the effect - not the cause - of these people's general disposition:

Answer choice (E):
No depression Social Interaction Increased left lobe activity

On a related note, had answer choice (A) stated that the drugs prescribed to combat depression decrease left lobe activity, then answer choice (A) would have had the same exact effect on the argument as answer choice (E). Do you see why?

[eober]

Diagrams helped a lot, thank you for the clarification!

[srcline@noctrl.edu]

Hello,

Nikki, maybe I can take a shot at why A is correct. So A actually strengthens the argument b/c it confirms that: lack a depression correlates w/ increased left lobe activity.

A helps solidify this b/c if people who are clinically depressed are being prescribed drugs to combat depression then they could have increased left lobe activity b/c they could be have lack of depression as a result of being proscribed these drugs.

I initially chose B, but lack of sleep would be a 3rd independent factor that would disrupt this correlation, where as drugs is another element but it strengthens the correlation.

Thankyou
Sarah

[David Boyle]

Hello,

Nikki, maybe I can take a shot at why A is correct. So A actually strengthens the argument b/c it confirms that: lack a depression correlates w/ increased left lobe activity.

A helps solidify this b/c if people who are clinically depressed are being prescribed drugs to combat depression then they could have increased left lobe activity b/c they could be have lack of depression as a result of being proscribed these drugs.

I initially chose B, but lack of sleep would be a 3rd independent factor that would disrupt this correlation, where as drugs is another element but it strengthens the correlation.

Thankyou
Sarah

Hello,

A may be a strengthener, as you say. Although I think you're trying to say that there's a causal chain from increased left lobe activity (cause) to lack of depression (effect).
Your next sentence seems to get things backward, though, since the chain is supposed to be from increased left lobe activity to lack of depression, not the other way around as you seem to say.
Lack of sleep is not purely independent, maybe, if it's a consequence of depression.

David

[lsat2016]

Hello,

Could you explain how C is incorrect? What does it mean for the causal factor to be "subject to variation"?

Also, I thought that A had no effect on the argument and not a strengthener because it points to a correlational relationship (increased left lobe activity correlates with decreased depression) whereas the conclusion is about a causal relationship. Is this correct?

Thank you!

[Clay Cooper]

Hi Lsat2016,

Thanks for your question.

Answer choice C is incorrect because the conclusion claims that one's general disposition is a result of one's frontal lobe activity, and answer choice C suggests that that causal relationship is impossible, which weakens the conclusion. The new information in C suggests that the relationship is impossible by introducing a difference that makes the two things - frontal lobe activity and general mood - so dissimilar that one cannot cause the other.

Let's say (as C suggests) that one's mood is variable. If frontal lobe activity is not variable, then frontal lobe activity is not likely to directly cause the variations in mood; a steady, consistent event like frontal lobe activity cannot account for the variations in mood we experience every day.

I think answer choice A, on the other hand, does strengthen the argument. A suggests that prescribing doctors try to treat depression by purposefully increasing left frontal lobe activity through the use of medication. If it is safe to assume that prescribing doctors have good reason for prescribing what they do (I think it is), then we can conclude that increasing left frontal lobe activity must in fact cause a reduction in the symptoms of depression.

I hope that helps!

[Jay]

Hi Powerscore, I got this one right, but C was a contender.

C was attractive because it seemed like it was strengthening the argument by eliminating the alternative (reversed causation).

If frontal lobe activity is not subject to variation the way general disposition is (which means frontal lobe activity does not depend on changes in general disposition), then isn't it essentially saying variations of general disposition does not cause frontal lobe activity? thereby strengthening the argument?

The initial argument was that frontal lobe activity causes general disposition change (not the other way around).

Thank you!

[Adam Tyson]

I, too, was thinking about answer C in that way for a bit, Jay, but here's the problem: if frontal lobe activity does not change, but general disposition does change, that breaks the correlation on which the argument is based. It's saying that a person's general disposition might change, but their frontal lobe activity remains constant. Thus, the change in general disposition cannot be caused by the activity of the frontal lobe!

[ltowns1]

I got this question right, but the more I've seen it the more I wanted to examine (E) a little further. Initially, I had a hard time seeing how social interaction equated to general disposition. but although (E) is mentioning those who are clinically depressed in it's answer, (E) is really addressing those people in the stimulus who have a good natured disposition, is that correct? It's saying that the mood they were in drove the activity in their frontal lobe. Once I saw that, I understood the connection between social interaction and general disposition better.