Vergence occurs when the eyes rotate inward (converge) to see a near object and then rotate outward (diverge) when we look at a more distant object. When you are looking at your finger resting against your nose, your eyes are rotated inward to focus on this very close object. Essentially, to see your finger, your gaze must become “crossed.” When you shift your gaze to the window or wall beyond your eyes, your eyes rotate outward from each other. This process is automatic, but we can sense the movements, and this gives us information about the distance of objects. It can provide the visual system with reliable depth information to about 2 m in length, at which point there is no appreciable difference in eye angle (Schachar, 2006).
Use this activity to explore how vergence helps us keep objects at different distances on the two foveas and as a result provides information about the depth of an object.
To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.
Below is a list of the ways that you can alter the illustration. The settings include the following:
Object Position: Moves the object closer or farther from the eyes.
Eye Separation: Makes the eyes closer or farther apart. The farther the separation, the greater the vergence change.
Pressing this button restores the settings to their default values.