Hering´s law and vergence: equal signals produce unequal responses

Vergence eye movements have long been thought to be the result of a single control signal which is equally distributed to the two eyes. Yet a detailed study of the responses of each eye shows that left and right eye movements can be quite different. A model is developed which provides excellent simulation results well matched to the experimental data. The model uses a single controller for both eyes, but achieves substantial asymmetry through the use of different time constants in the neuromuscular plants of the left and right eye