Why does Listing's plane rotate during vergence?

Recall the afterimage experiment. A horizontal line (gray) had the following orientations relative to the horizontal meridian (yellow-green) of the eye (the after image).

When the eyes converge

  • the right eye is looking left
  • and the left eye is looking right

When looking up while converged the horizontal gray lines should have different orientations on each eye and thus be perceived as a torsional disparity.

Likewise when looking down you should perceive a torsional disparity but in the opposite direction.

Copyright © 1996 Tutis Vilis and Douglas Tweed
University of Western Ontario
London Ontario Canada
Updated October 28, 2005

Comments welcome. Email to tutis.vilis@schulich.uwo.ca