Title page for ETD etd-12172008-063057

Type of Document Master's Thesis
Author Fajardo, Ann B.
URN etd-12172008-063057
Title Does vergence influence the vestibulo-ocular reflex in human subjects rotating in the dark?
Degree Master of Science
Department Engineering Mechanics
Advisory Committee
Advisor Name Title
Grant, John Wallace Committee Chair
Kraige, Luther Glenn Committee Member
Love, Brian J. Committee Member
  • vestibulo-ocular reflex
  • eye movements
  • vergence
Date of Defense 1996-07-15
Availability restricted

In recent experiments involving acceleration stimuli, researchers instructed subjects to focus on a visual target while measuring the vestibulo- ocular reflex (VOR) in one eye. These experiments showed conclusively that the VOR is influenced by target distance. We, on the other hand, were interested in investigating the VOR of subjects accelerated in complete darkness. Specifically, we wished to determine the subject's vergence point, which cannot be accomplished using data obtained from only one eye. Hence, a binocular eye-tracking system that works in the dark was required. In the experiment described in this thesis, the subject was rotated in the dark on NAMRL's Coriolis Acceleration Platform. The position of each pupil center was tracked and recorded by two helmetmounted infrared cameras connected to a computer-controlled data acquisition system. The position data were used to calculate the angles through which the eyes rotated, and then trigonometric principles were applied to construct the line of sight for each eye for any moment in time; the intersection of these two lines is the vergence point. With the NAMRL binocular eye-tracking system, an accelerating subject's vergence point can accurately be determined if it is less than 1. 5 meters away. The vergence data obtained from this experiment suggest that vergence distance does not exclusively drive the VOR in the dark.

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