PrepTest 151

Incorrect. The premise is about highly skilled musicians, not highly skilled piano players (though it does rely on being able to distinguish piano sounds).

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Musicians have a larger area of the brain that can tell sounds apart than non-musicians, so practicing/playing an instrument causes your brain to change structure.

Answer Anticipation:
The conclusion here has causal language—"alters." It's based on a correlation between a certain section of the brain's size and musical skills. That's a classic correlation/causation flaw, and the correct answer might directly point that out.

That said, we know that it's a flaw to jump between correlation and causation for several reasons, two of which tend to show up frequently in correct answers. The first is an alternative cause that leads to both of the correlated phenomena; the second is reversed causality. And when reversed causality makes sense, it does tend to be the correct answer. Here, reversed causality does make sense—it's quite possible that having a brain structured to distinguish music sounds better than average would lead one to music! We should keep looking for other correlation/causation answers, but let's also keep an eye out for reversed causality in the answer choices.

Answer Explanation:
This answer points out that the argument doesn't rule out the causal relationship flowing in the reverse direction, so it's the correct answer. It's possible those with a brain structure naturally more able to distinguish between piano sounds become musicians because of this ability.

Key Takeaway:
Reversed causality shows up less on the LSAT than other types of correlation/causation flaws, but when it makes sense, it tends to show up. There are two places where this is most common. The first is in arguments on medical topics. The second is when the premises don't establish for certain that one of the related phenomena happens first. This falls into the latter category (and arguably is in the world of the former).

Incorrect. The argument draws a conclusion about the brain structure of musicians based on premises about the brain structure of musicians, so it's not jumping from a narrow to a broad range.

Incorrect. First, this answer doesn't state that the certain area of the brain is the same area as the one from the stimulus. Even if it were, the conclusion is that practicing and playing an instrument impacts brain structure, so it'd be expected that those who listen to but don't play instruments wouldn't have that larger brain structure.

Incorrect. The argument never compares the size of this area of the brain in people of varying skill levels—just those who have learned to play an instrument versus those who didn't. Since the comparison between musicians of different skill levels is out of scope of the argument, so is this answer.