Logical reasoning PrepTest 130 · Section 3 · Question 17

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Mountain climbers past 6k meters started: 1) slurring their speech; 2) taking longer to understand sentences; 3) demonstrated poor judgment. So the part of the brain controlling speech is the same part that controls other functions.

Answer Anticipation:
Let's work backwards from the conclusion here, as that can help us make sense of the list of symptoms demonstrated by the climbers and why they matter.

That conclusion states that the combination of symptoms "disproves the theory" that speech and other functions are controlled by different parts of the brain. If a theory saying that speech and other functions are controlled by different parts is "disprove[n]", then it must mean that the same part of the brain controls speech and other functions.

So what about the list of symptoms suggests that? Well, speech was affected by the diminished oxygen, but so was comprehension and judgment. So the study did show that the oxygen deprivation could affect multiple functions of the brain, including speech. But does that prove that the same area of the brain controls them?

Only if the oxygen deprivation affected only one part of the brain. If oxygen deprivation affects the whole brain, or different parts of the brain, then the impaired functions experienced by the mountain climbers could have been the result of different parts of the brain being deprived of oxygen.

The argument assumes that oxygen deprivation affects only one part of the brain. The question stem asks us to find a possibility that the argument overlooks. Let's find an answer stating that the argument overlooks the possibility that the oxygen deprivation affected multiple parts of the brain.

Answer Explanation:
The argument assumes that only one part of the brain is affected by oxygen deprivation, so it overlooks the possibility that multiple parts of the brain are affected by it. This answer choice takes that to the extreme—the entire brain is affected by oxygen deprivation—so it's the correct answer. If this were true, then we couldn't tie the various effects of oxygen deprivation to a single part of the brain, and thus we can't tie the speech part of the brain to other parts/functions.

Key Takeaway:
So many of the incorrect answers here didn't address the key element of the argument—different areas of the brain being affected by oxygen deprivation. The stronger your grasp of the core of an argument, the easier it is to eliminate answers that are out of scope.

Incorrect. What matters is the difference between their pre-climbing skills and their post-6100m skills. This answer just highlights that the climb had some effect on their speech, comprehension, and judgment; it doesn't tie into the parts of the brain affected.

Incorrect. The climbers having different levels of impairment doesn't speak to the areas of their brain affected by oxygen deprivation.

Incorrect. 5,999m would still count as high altitude, and so this answer wouldn't change anything in the stimulus. Additionally, it doesn't address the portions of the brain affected.

Incorrect. This answer suggests that they may have ended up at a higher altitude than the average person before they started to get impaired, but that doesn't address how many parts of their brain were affected by the oxygen deprivation.