What is motion parallax and how does it contribute to depth perception?

Motion parallax refers to the effect whereby objects at different distances from an observer appear to move at different relative speeds when the observer changes their position. This phenomenon occurs because closer objects appear to move more rapidly across the visual field compared to distant objects, which seem to move more slowly.

As an individual shifts their viewpoint—whether by turning their head or walking—the nearby objects will shift position significantly against the more distant background. This difference in motion provides critical visual information that the brain uses to gauge relative distances between objects. By interpreting these varying speeds of movement based on distance, the brain constructs a sense of depth in the visual scene, allowing for better spatial awareness and navigation.

This process contributes significantly to depth perception, as it helps the brain determine not just how far away objects are, but also how they relate to each other spatially in a three-dimensional environment. The other options do not accurately describe motion parallax or its role in depth perception, focusing instead on unrelated aspects such as color blending, measuring speed without context, or brightness.