Abstract

In the flash-lag effect a non-moving object is quickly flashed directly underneath a moving object, which leads us to perceive the non-moving object as “lagging” the moving object, even though the two objects actually occupy the same horizontal position at the time of the flash. In the example above, for instance, a red square moves across a screen. At the midpoint of the red square’s journey from one side to the other, a green square is quickly presented (flashed) just below. Despite the fact that the two stimuli are presented at the same coordinates along the x axis, the stationary square is perceived as behind the moving square. The perceived lag of the flashed stationary object becomes greater when the speed of the moving object is increased and vice versa (Nijhawan 1994).