title: Ocular proprioception and efference copy in registering visual direction.
abstract: We measured the roles of eye muscle proprioception ("inflow") and efference copy ("outflow") in registering eye position. During monocular fixation, pressing on the side of an occluded eye results in a passive rotation, changing the proprioception without affecting oculomotor efference. As we have shown previously, a constant press on the side of the viewing eye induces active resistance to rotation, changing efference because oculomotor innervation compensates for the eyepress; the viewing eye's fixation remains constant. Using these two types of eyepress, both perceived target deviations and pointing biases in an unstructured visual field were measured in 8 subjects under efference copy, proprioception and control (no eyepress) conditions. Eye deviation was measured photoelectrically. Physiological gains of efference copy and proprioception was about 5/8 and 1/4 respectively. There was no statistically significant difference between perceptual judgement and open-loop pointing. The sum of gains of efference copy and proprioception, about 7/8, indicates incomplete registration of eye eccentricity in an unstructured field, and quantitatively accounts for several previously unexplained results in the literature.
authors.affiliation: Program in Experimental Psychology, University of California, Santa Cruz 95064.
authors.forename: B
authors.initials: B
authors.lastname: Bridgeman
authors.forename: L
authors.initials: L
authors.lastname: Stark
mesh_terms: D000328:Adult; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D009801:Oculomotor Muscles / Q000294:innervation*; D011312:Pressure; D011434:Proprioception / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology