Which law states that for any position of gaze, the eye has a unique orientation in 3 dimensions in space?

• A. Hering's Law
• B. Sherrington's Law
• C. Troxler Effect
• D. Donder's Law

Answer: (D)

Donder's Law describes how the eye ends up in a precise orientation in three-dimensional space for any given gaze direction. For a chosen line of sight, the eye settles into a unique combination of horizontal, vertical, and torsional positions, and this orientation is determined by where you are looking rather than how you got there. That means the same gaze direction will produce the same eye orientation every time, including the amount of torsion.

This is why Donder's Law is the best fit: it directly links gaze direction to a specific, repeatable eye orientation in space. The other options describe different ideas: Hering's Law concerns equal innervation to yoked muscles, Sherrington's Law addresses reciprocal innervation of antagonists, and the Troxler Effect is a perceptual fading phenomenon—none of these define how the eye’s orientation is uniquely determined by the gaze direction.