system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do our eyes often suddenly perceive spinning movements as slower than their actual speed once a certain speed threshold is reached?

This refers to the effect often seen in strobe discs used for turntables, zoetropes for incredibly old films, and even things as basic as car wheels, in which at when objects spin fast enough our eyes suddenly view them as spinning slowly. Is this linked to saccades?
gpt
Common misconception: Your eyes operate in a certain frames per second. The issue with this is that our eyes don't operate in 'frames.' It's much more complex.

However, the frames per second method is the easiest way to explain it. So, imagine a camera is recording a helicopter. The camera is recording in a smooth 60 fps, and the helicopter's blades are spinning at 60 RPS (3,600 RPM- way higher than an actual helicopter, but this makes for easy math). So, each time the helicopter makes one complete rotation, the camera records a frame. It is in the same position as the previous frame, and as the next frame. This creates the illusion that it is in the same location.

However, math doesn't always work out, so often, things will actually be just above or below this perfect threshold that allows us to see it in the same place. This creates the illusion that it's slightly spinning forwards or backwards. It might be different for different people- it's really based on how fast the brain can organize the information your eyes are giving you, however, there's always a limit. Your brain often simplifies the information it receives instead of completely ignoring it, resulting in motion blur.