Suppose that you are viewing two objects at different distances in the same line of vision. What can you determine about these objects by moving your head back and forth? (Hint: Think about motion parallax.)

Which object is closer (motion parallax)

Explanation:

Motion parallax: It is related to the perceptual organization. Motion parallax provides the differences between the object, how far away the object and motion of the objects. It is also related to depth perception.

For instance when you driving a car and you see the tree moving towards you gradually but left it very speedily. It indicated that the objects moving with your head back and forth depending on the motion and distance of an object.