<P> When a large part of the visual field moves, a viewer feels like he has moved and that the world is stationary . For example, when one is in a train at a station, and a nearby train moves, one can have the illusion that one's own train has moved in the opposite direction . Common sorts of vection include circular vection, where an observer is placed at the center of rotation of a large vertically - oriented rotating drum, usually painted with vertical stripes; linear vection, where an observer views a field that either approaches or recedes; and roll vection, where an observer views a patterned disk rotating around his or her line of sight . During circular vection, the observer feels like he is rotating and the drum is stationary . During linear vection, the observer feels like he has moved forwards or backwards and the stimulus has stayed stationary . During roll vection, the observer feels like he has rotated around the line of sight and the disk has stayed stationary . </P> <P> Inducing vection can also induce motion sickness in susceptible individuals . </P> <P> After being on a small boat for a few hours and then going back onto land, it may feel like there is still rising and falling, as if one is still on the boat . It can also occur on other situations, such as after a long train journey . It is not clear whether sea legs is a form of aftereffect to the predominant frequency of the stimulation (e.g., the waves or the rocking of the train), whether it is a form of learning to adjust one's gait and posture, or whether it is a form of the Tetris effect . Sea legs needs to be distinguished from mal de debarquement, which is much more disturbing and long - lasting . </P>

Why do i still feel like im on the boat
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