GMAT CR: Experimental & Causation Questions

Once again, the key to CR questions isn’t fully understanding the story, but rather understanding the underlying patterns.

124. It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. In fact, however, simply talking to other people—that is, participating in social interaction, which engages many mental and perceptual skills—suffices. Evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills.

Which of the following, if true, most seriously weakens the force of the evidence cited?

After reading the question, we can identify two common GMAT CR question structures:

Cause-and-effect conclusion: A leads to B (talking to people improves mental sharpness).
Experimental report: Group A exhibits characteristic B (people with more social interaction have better mental skills).

For cause-and-effect conclusions, the most likely weakening strategies are:

– Reversing cause and effect
– Identifying an alternative cause

For experimental report questions, the most likely weakening strategies are:

– Reversing cause and effect (perhaps better mental skills lead to more social interaction)
– Identifying an alternative cause (perhaps the group with more social interaction shares another common trait that leads to improved mental skills).

The conclusion of the question is whether social interaction improves mental sharpness/skills. In other words, we are looking for the cause.

(A) As people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them.
This doesn’t identify the actual cause of improved mental skills.

(B) Many medical conditions and treatments that adversely affect a person’s mental sharpness also tend to increase that person’s social isolation.
This points to an alternative cause: “medical conditions and treatments.”

(However, this option describes the inverse: treatments that harm mental sharpness also tend to reduce social interaction. It clearly indicates that social interaction doesn’t necessarily directly affect mental sharpness, and it’s possible that both are coincidentally the result of an alternative cause.)

(C) Many people are proficient both in social interactions and in solving mathematical problems.
This doesn’t identify the cause of improved mental skills.

(D) The study did not itself collect data but analyzed data bearing on the issue from prior studies.
This seems to question the reliability of the data, but it doesn’t state that the prior studies were unreliable. Therefore, it doesn’t constitute an effective challenge.

(E) The tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.
This is irrelevant. It states that the experimental design leaned more towards math problems than conversation. However, it doesn’t question the accuracy of the experiment. Even if the experiment leaned more towards math problems, it doesn’t mean the data on social interaction within the experiment is unreliable.

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