The Cobra Effect · Horst Siebert

The cobra effect examples

Curated by · reviewed 2026-06-01

When you reward a number, people optimise the number — often in ways that make the real problem worse. The incentive backfires.

What is the cobra effect? Read the full idea →

5 examples of the cobra effect

  1. The cobra bounty

    Colonial India paid for dead cobras; people bred cobras for the reward, and when the scheme ended, released them — more cobras than before.

  2. Paying per bug fixed

    Reward fixing bugs and developers quietly create bugs to fix later.

  3. The Hanoi rat tails

    A bounty on rat tails led people to cut tails and free the rats to breed and earn again.

  4. Lines of code as a target

    Measure productivity by code volume and you get bloated, padded software.

  5. Test-score pressure

    Reward schools purely on test scores and they teach to the test or quietly push out weak students.

How to spot it in yourself

You'll forget most of this by next week.

That's just how memory works. Lock the cobra effect in with a 5-minute active-recall session — spaced repetition, no signup.

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