Hering's law of equal innervation

Hering's law of equal innervation is used to explain the conjugacy of eye movements (saccades) in stereoptic animals. The law which was put forward by Hering in the 19th century proposes that conjugacy of saccades is due to innate connections in which the eye muscles responsible for each eye's movements are innervated equally. The law also states that apparent monocular eye movements are actually the mathematical summation of conjugate version and vergence eye movements

This theory is in contrast to the theory proposed by Von Helmholtz (1911) which states that conjugacy is a learned, coordinated response and that the movements of the eyes are individually controlled. Although for most of the 20th century, it was believed that Herring was right, recent evidence has suggested that the eye movements may be separately encoded.