Helmholtz favored a motor outflow version of the local sign doctrine for two main reasons. First, he was skeptical that afferent registrations of eye position are precise enough to play the role assigned to them by Lotze’s theory (2005 [1924]: 47–49). Recent research has shown that proprioceptive inflow from ocular muscular stretch receptors does in fact play a quantifiable role in estimating direction of gaze, but efferent outflow is normally the more heavily weighted source of information (Bridgeman 2010; see  Section 2.1.1 below).