title: The effect of volition on the horizontal forced-vergence fixation disparity curve.
abstract: An anomalous horizontal forced-vergence fixation disparity curve in the shape of the letters V or U is presented. This phenomenon is associated with an increase in eso fixation disparity with base-out prism. This response is shown to be related to instructional set. Intrusion of voluntary vergence is suggested as the most likely basis for this effect.
authors.affiliation: School of Optometry, University of Missouri-St. Louis.
authors.forename: R P
authors.initials: RP
authors.lastname: Garzia
authors.forename: S B
authors.initials: SB
authors.lastname: Nicholson
mesh_terms: D000065:Accommodation, Ocular; D003290:Convergence, Ocular; D005133:Eye Movements; D005403:Fixation, Ocular; D006801:Humans; D014836:Volition