Annals of Biomedical Engineering

, Volume 23, Issue 4, pp 409–422

A review of the role of efference copy in sensory and oculomotor control systems

  • Bruce Bridgeman
Starkfest: Vision & Movement in Man and Machines Perceptual-Motor Interactions


Efference copy is an internal copy of a motor innervation. In the oculomotor system it provides the only extraretinal signal about eye position that is available without delay, and it is shown to be the most important extraretinal source of information for perceptual localization and motor activity. Efference copy accompanies all voluntary eye movements and some involuntary ones, including pursuits, saccades, and the fast phases of vestibular and optokinetic nystagmus. Not all eye movements are accompanied by an efference copy; its presence is determined by a movement's function, not it dynamics. Because the gain of the efference copy mechanism is less than 1, and it does not take account of oculomotor delays and kinematics, it is supplemented by other mechanisms in achieving space constancy. It functions differently for perception and for visually guided behavior. There is only one efference copy for both eyes, reflecting Hering's law, and it is subject to adaptation.


Corollary discharge Efference copy Eye movement Saccade Space constancy 


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Copyright information

© Biomedical Engineering Society 1995

Authors and Affiliations

  • Bruce Bridgeman
    • 1
  1. 1.Program in Experimental PsychologyUniversity of California, Santa CruzSanta Cruz

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