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SESK: Stuff Everyone Should Know · sesk.info/drone-autokinesis-illusion

At night, a stationary light seems to drift after you stare at it. What is this illusion?

That false motion is called autokinesis.

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  1. Ground effect
  2. Autokinesis ✔
  3. Wind shear

Why: With few surrounding references, a fixed light can seem to move after a prolonged stare. Scanning instead of fixating helps prevent the illusion.

Huh, didn't know that: The AIM warns that a pilot trying to line up with the drifting light can become disoriented.

The dad joke
The stationary light claimed it never moved, but the eyes had a different story.
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References

Answer: Autokinesis. With few surrounding references, a fixed light can seem to move after a prolonged stare. Scanning instead of fixating helps prevent the illusion.

  1. FAA Aeronautical Information Manual, Medical Facts for Pilots www.faa.gov/air_traffic/publications/atpubs/aim_html/chap8_section_1.html
    In the dark, a static light will appear to move about when stared at for many seconds.
    Checked 2026-10-09.

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