When an object is removed from the front of the eye, its sensation stays in the brain for 1/10 second of removal . This period is called the period of permanence of vision. If an object can be removed from the front of the eye and then brought back to the eye within one tenth of a second, then the object has not been removed from the front of the eye for the sake of visual perception. For this reason, when a burning torch turns loudly in front of our eyes, we see a circle of fire in our eyes, although at different times the torch is in different places.