If this illusion occurs during a low-speed final approach, the pilot could stall the aircraft.
The authors suggest that the illusion occurs because of the way the visual system takes into account perspective.
Sensory illusions occur when these models do not match up.
With the addition of the support shelves, this illusion does not occur.
To put it more simply, this illusion occurs when certain "wrong" signals override "right" ones and reach the brain first.
Some illusions occur as result of an illness or a disorder.
This optical illusion also occurs with the Sun and star constellations.
The illusion occurs when the light is bent by gravity as it passes through an intervening galaxy.
Over time however the brain adapts and although these illusions can still occur, most astronauts begin to see "down" as where the feet are.
But a strange illusion occurred as he drew closer.