The striped sheet beyond the pole: the red dots on it go sideways, never up.
Tricks of motion
Barber pole illusion
Which way are the stripes moving?
Sideways, as the pole turns, though they seem to move up.
Why? Through a long narrow opening, your brain can only tell the stripes move along the long side, so it sees them going up.
Picture: Drawn by Science Playground · Wikipedia(opens in a new tab)