Self-motion Perception from Optic Flow and Rotation Signals

The value of optic flow for retrieving movement direction was recognised already two centuries ago by astronomers, searching the sky for meteorite showers. The point from which the shower appeared to emanate they termed the radiant, knowing it indicated the direction along which the meteorites were heading towards the observer. As Gibson (1966) pointed out, humans may use the shower of light that hits the eye ball when the eye moves relative to the stable world, to retrieve their direction of movement relative to the world (heading). Motion pictures nowadays offer opportunities to a larger audience to appreciate the value of optic flow in isolation. The ongoing display of a diverging cluster of stars, trademark of a well-known movie maker and popular among the screensavers, can bring about a strong sensation of moving forward while in fact one remains seated.