The problem of visual direction constancy (VDC) is the problem of how we perceive a stable world despite variations in visual stimulation caused by saccadic eye movements. When we execute a saccade, the image of the world projected on the retina rapidly displaces in the direction of rotation, yet the directions of perceived objects appear constant. Such perceptual stability is crucial for ordinary visuomotor interaction with surrounding the environment. As Bruce Bridgeman writes,