Affiliations: [a] Institute of Clinical Neurosciences, University of Munich, Munich, Germany | [b] German Center for Vertigo and Balance Disorders, University of Munich, Munich, Germany | [c] Brandenburg University of Technology Cottbus – Senftenberg, Senftenberg, Germany | [x] Otological and Skull Base Surgery Department, S.M. delle Scotte Hospital, Siena, Italy | [y] Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy
Correspondence:
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Corresponding author: Thomas Brandt, Institute of Clinical Neurosciences, University of Munich, Marchioninistr. 15, 81377 Munich, Germany. Tel.: +49 89 4400 72380; Fax: +49 89 4400 78883; E-mail: thomas.brandt@med.uni-muenchen.de
Abstract: Fear of heights is elicited by a glance into an abyss. However, the visual exploration behavior of fearful subjects at height has not been analyzed yet. We investigated eye- and head movements, i.e. visual exploration behavior, of subjects susceptible to fear of heights during exposure to a visual cliff. The movements of eyes and head were recorded in 19 subjects susceptible to fear of heights and 18 controls while standing still on an emergency balcony 20 meters above ground level for periods of 30 seconds. Participants wore mobile, infrared eye-tracking goggles with inertial sensors for recording head movements. Susceptibles exhibited fewer and smaller-amplitude eye-in-head saccades with fixations of longer duration. Spontaneous head movements were reduced by 49% in susceptibles with a significantly lower mean absolute angular velocity (5.3°/s vs. 10.4°/s), and all three dimensions (yaw, pitch and roll) were equally affected. Gaze-in-space – which indicates exploration by coordinated eye-head movements – covered a smaller total area of the visual scene (explored horizontal angle: 19° vs. 32°, vertical: 9° vs. 17°). We hypothesize that the susceptibles suppress eye and head movements to alleviate fear of heights. However, this behavior has the potential disadvantage of impairing the visual stabilization of postural balance.
