PrepTest 106, Section 1, Question 23
Further evidence of a connection between brain physiology(61 more words not shown)
Each of the following, if(5 more words not shown)
- AMany drugs prescribed(11 more words not shown)
- BExcessive sleep, a(12 more words not shown)
- CFrontal lobe activity(10 more words not shown)
- DEarlier studies indicated(17 more words not shown)
- ESocial interaction of(17 more words not shown)
Reading the argument
Maybe the mood changes the brain activity, rather than the brain activity producing the mood.
The technical language describes an association. The depressed participants show less activity in the left frontal lobe than in the right; the good-natured participants show greater left-lobe activity. That gives us a pattern to explain. It doesn't, by itself, tell us which way the influence runs. Perhaps being in a certain mood affects what is happening in the brain.
I'd also question how far the conclusion extends. The study compares depression with being characteristically good-natured, while the conclusion concerns a person's general disposition. Are those observations enough to support such a broad explanation? That is a question about the reach of the evidence, not a claim that the observed pattern is false.
What we’re looking for
This is a weaken EXCEPT question. Four choices will challenge the argument, and one won't. My clearest prediction for a weakener is evidence that the mood helps produce the brain-activity pattern. But we should check all four challenges; they don't have to use the same route.
Working the answers
- ACorrect
A drug combating depression by increasing left-lobe activity fits the proposed direction: a change in that activity can affect the psychological state. It doesn't undermine the claim that frontal-lobe activity influences disposition.
That makes A the exception we want. It needn't prove the author's whole broad conclusion. On a weaken EXCEPT question, supporting the proposed connection rather than challenging it is enough to distinguish A from the four weakeners.
- B
Follow the steps: depression leads to excessive sleep, and excessive sleep suppresses left-lobe activity. That supplies a way for depression to help cause the brain pattern the study found.
The author moves from the pattern to a claim that frontal-lobe activity produces the disposition. B offers the direction we questioned while reading: the psychological state could help produce the activity difference. It weakens that inference without denying that the association exists.
- C
This challenges how well frontal-lobe activity can explain changes in disposition. If disposition varies in ways that frontal-lobe activity does not, pointing to that activity leaves the variation unexplained.
For example, imagine a person's disposition changing while the relevant frontal-lobe activity stays the same. That would make it harder to attribute the change in disposition to a change in that activity. The example illustrates the mismatch; C doesn't have to say that the frontal lobe is completely inactive or that its activity can never change in any way. It casts doubt on the proposed explanation, so it isn't our exception.
- D
This gives both features a shared cause. Activity in the limbic system could produce both the frontal-lobe pattern and the emotional state. They would then appear together without the frontal-lobe activity having to cause the emotional state.
That differs from the reversed-direction prediction, but it still weakens the inference. Also, the limbic system is part of the brain; D isn't evidence that the brain has nothing to do with mood. It challenges the specific causal role assigned to frontal-lobe activity.
- E
Social interaction stimulates left-lobe activity, and most clinically depressed people don't engage in the relevant kind of interaction. That offers another way to explain why the groups differ in brain activity: their different social behavior could help produce the difference.
We don't need to claim that the brain shrinks or that social interaction cures depression. The stated connection is enough to question whether the observed activity difference shows that the frontal lobe causes the disposition, rather than reflecting differences in what the participants do.
More Weaken questions
Learn the LSAT our way
Our platform drills Weaken questions at your level and adjusts as you improve.