Notes

The Cobra Effect

  • Updated July 2, 2025
  • 1 minute read
The Cobra Effect

= 眼鏡蛇效應

A well-intentioned measure can often backfire and have the opposite effect to intended.

A famous story on the power (or danger) of incentives:

There were too many cobras in India.

The British colonists, worried about the dangers of these venomous creatures, devised a plan to reduce the cobra population:

They offered bounties for cobra heads.

Some savvy locals developed a business model: Breed cobras, chop of their heads, turn in cobra heads and collect bounties.

The British realized what was happening and ended the policy.

In response, many of the breeders simply released their now-worthless cobras onto the streets, increasing the population of cobras.

The Cobra Effect is an example of Goodhart’s Law, which says that when a measure becomes a target, it ceases to be a good measure. Simply put, if a measure of performance becomes a stated goal, humans tend to optimize for it, regardless of any associated consequences. The measure often loses its value as a measure.

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Updated July 2, 2025 • 10 days ago
© 2025 • Hua-Ming Huang licensed under CC BY 4.0

Hua-Ming Huang

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