PrepTest 144

Incorrect. If the ginkgo levels were higher, that could suggest an even greater effect and thus help the argument.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:

Study 1:
Ginkgo-fed mice - More likely to remember how to navigate a maze
Normal-diet mice - Less likely to remember how to navigate a maze

Study 2:
Ginkgo reduces mouse stress, and lowering very high stress improves memory

Conclusion - The ginkgo may not have a direct effect on memory

Answer Anticipation:
An interesting argument that features two studies, some correlations, some causation, and a conclusion that suggests something might not cause something else . . . well, at least not directly. In short, there's a lot going on.

The first study shows a correlation between mice who had ginkgo in their diet and remembering a path through a maze. It also had a control group to show that the maze times were lower in the first group. This correlation can't prove causation—though, as with all correlations, it provides evidence for it.

The second study does have a causal relationship established—the stimulus notes that ginkgo "reduces" stress, and lowering very high stress levels "improve[s]" memory in mice. So we do have some causal premises.

The argument then concludes that ginkgo may not directly enhance memory. Based on the argument's use of the second study to support this, the argument is assuming that the ginkgo reduced stress, and the reduced stress improved memory.

However, there's an important caveat on that second study—reducing "very high stress levels" is known to improve memory. Without knowing if the mice in the first study were under such high stress levels, we can't tell if the ginkgo worked by lowering them or if it worked to directly aid memory. To weaken this argument, therefore, we should look for an answer that states the mice weren't under very high stress levels.

Answer Explanation:
The causal relationship from the second study showed that reducing "very high" stress levels improves recall. If the mice in the first study weren't under "very high" levels of stress, then even if the ginkgo reduced their normal stress levels a bit, it wouldn't improve recall and thus the ginkgo may have directly improved memory. That runs counter to the conclusion, so this answer weakens the argument.

Key Takeaway:
When an argument has many moving parts, be sure that you understand how they work together. Here, the intersection of the two studies was important in finding the correct answer.

Incorrect. These other chemicals aren't known to be present in this study, but ginkgo was in the study and it has been shown to reduce stress.

Incorrect. Not knowing how a chemical works doesn't preclude knowing that it does work, so this answer choice doesn't weaken the argument.

Incorrect. The argument considers whether ginkgo is a potential cause of enhanced memory, not enhanced intelligence/ability to learn, so this answer is out of scope.