QUESTION TEXT: When chimpanzees become angry at other chimpanzees,…
QUESTION TYPE: Paradox
PARADOX: Chimpanzee anger can lead to both threat gestures and attacks. But threat gestures are rarely followed by attacks, and attacks rarely are preceded by threat gestures.
ANALYSIS: You might wonder why the stimulus says both of these things:
- Attacks rarely come after threat gestures.
- Attacks are rarely preceded by threat gestures.
These sound similar, but they are very different. The first refers to the odds of an attack, if you have a threat gesture. The second refers to the odds that a threat gesture occurred, if there was an attack.
Let’s imagine two situations:
- 1,000 threat gesture incidents, 10 attacks, all attacks preceded by threat gestures
- 1,000 threat gesture incidents, 500 attacks, only 30 attacks preceded by threat gestures
In the first situation, it’s true that attacks rarely come after threat gestures. But attacks are always preceded by threat gestures. So the first situation contradicts the second fact.
The second situation is consistent with both facts. Attacks rarely come after threat gestures. And threat gestures rarely come before attacks.
- This explains why chimps make threat gestures, but it doesn’t explain why chimps don’t attack.
- CORRECT. Threat gestures prevent chimps from having to make attacks. This explains why attacks rarely are preceded by threat gestures – if the chimps had made threat gestures then they wouldn’t have felt angry enough to attack.
- Suppose chimpanzees also display aggression by making funny faces. How does that explain anything about attacks and threat gestures?
- This doesn’t explain why chimpanzees don’t attack after making threat gestures.
- Tempting, but this statement doesn’t explain why threat gestures don’t lead to attacks. This is just a fact about chimpanzees.
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