Why can a stationary train seem to move when a nearby train begins moving?

The experience of a stationary train appearing to move when a nearby train begins to travel is a classic example of induced movement.1

This phenomenon occurs because the human visual system relies on a stable frame of reference to judge motion. When you are seated in a stationary train and look out the window at a neighboring train that begins to move, your brain often incorrectly adopts the larger, moving object as the stable background. Because your brain perceives the moving train as the stationary frame of reference, it interprets the relative change in position as evidence that your own train is the one in motion.1

This effect highlights our tendency to use the surrounding environment to anchor our perception of movement, demonstrating that the brain actively constructs the experience of motion rather than simply recording visual input passively.12