The Mechanism of Physiological Height Vertigo: I. Theoretical Approach and Psychophysics

Abstract

A theory is presented supporting a geometrical explanation of physiological height vertigo as a 'distance vertigo' created by visual destabilization of posture when the distance between the observer and visible stationary contrasts becomes critically large. Though height vertigo is generally regarded as a psychopathological process, we hypothesize that it might instead result from an intersensory mismatch when visual information is at variance with vestibular and proprioceptive inputs. Psychophysical experiments confirming the hypothesis revealed that: 1) height vertigo is clearly related to body position, being the greatest in the upright stance; 2) it is the eye-object distance rather than the direction of gaze which is critical; 3) there is a saturation of height vertigo magnitude. Subjective vertigo increases with increasing altitude only below 20 metres. Physiological 'distance vertigo' must be distinguished from psychological 'acrophobia'. Its postural consequences may be ameliorated by strategies gleaned from knowledge of its mechanism such as providing nearby stationary contrasts in the peripheral visual field. A( / ( I O/o/<irvug<d HY

Visual control of posture in real and virtual environments

“…These experiments have been conducted using real environments (Brandt, Arnold, Bles, & Kapteyn, 1980;Diener et al, 1984;Edwards, 1946;Guerraz, Sakellari, Burchill, & Bronstein, 2000;Lasley, Hamer, Dister, & Cohn, 1991;Paulus et al, 1984;Paulus, Straube, Krafczyk, & Brandt, 1989;Stoffregen, Smart, Bardy, & Pagulayan, 1999;Witkin & Wapner, 1950), as well as virtual environments (Dijk stra et al, 1992;Kelly et al, 2005;Mitra, 2003;Mitra & Fraizer, 2004). To our knowledge, no direct comparison of postural control in stationary real and virtual environments has been conducted.…”

Deconstructing acrophobia: physiological and psychological precursors to developing a fear of heights

“…[13] Despite the parallels to acrophobia, authors in the heights vertigo literature are at pains to dissociate the two. [9] Nonetheless, it seems possible that acrophobia could be regarded as an extreme response to this normal warning signal.…”

“…One concerns the related phenomenon of heights vertigo: a warning signal created by loss of postural control when the distance between the observer and visible stationary objects becomes too large. [9] The explanation for this everyday loss of postural control is that the increased distance between the observer and the nearest available visual targets reduces motion parallax cues. [10] The lack of these important depth cues leads to a perceptual conflict, as the vestibular and somatosensory receptors sense a body shift not detected by the visual system.…”

Visually induced postural sway in anxiety disorders

“…However, many patients with anxiety complain of discomfort in situations that are challenging for patients with balance disorders. These situationally specific symptoms include "supermarket syndrome" (Rudge and Chambers, 1982) "space phobia" (Marks, 1981), "visual vertigo" (Bronstein, 1995), and "height vertigo" (Brandt, et al, 1980). We have labeled this patterns of situationally specific symptom elicitation "Space and Motion Discomfort" (SMD) and developed a questionnaire to detect this condition (Jacob, Woody et al, 1993).…”