---
title: The Cobra Effect
created: 2024-11-18T09:18:12
modified: 2025-11-20T18:10:27
---

= 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](incentives.md):

> 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](https://sketchplanations.com/goodharts-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.