One of the binocular cues is convergence.  This is a neuromuscular cue which causes one's eyes to turn inward when focusing on a closer object.  This allows the brain to know which object to focus on.  In the first picture, the eyes turn inward more because the pencil being looked at is held at a close distance.  In the second picture, the eyes are farther apart as they focus on the pencil, which is at an arm's length.